Structural diversity and magnetic properties of copper(ii) quinaldinate compounds with amino alcohols

This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6899 Cite this: New J. Chem., 2022, 46, 6899 Structural diversity and magnetic properties of copper(II) quinaldinate compounds with amino alcohols† Nina Podjed, a Barbara Modec, * a Rodolphe Cle ´rac, b Mathieu Rouzie `res, b Marı ´a M. Alcaide c and Joaquı ´nLo ´pez-Serrano c The reactions between [Cu(quin) 2 (H 2 O)] (quin  = the anionic form of quinoline-2-carboxylic acid) and a series of aliphatic amino alcohols have yielded structurally very diverse copper(II) complexes, labelled a–g. Single-crystal X-ray structure analysis has revealed either intact amino alcohol molecules or amino alcoholate ions serving as ligands. In type acomplexes, the amino alcohols are bound in a monodentate manner via NH 2 . Engagement of both functional groups in coordination was observed for types band e (a bidentate chelating mode) and type c(a bidentate bridging one) complexes. In view of the strong bidentate chelating coordination of quinaldinate in [Cu(quin) 2 (H 2 O)], the formation of homoleptic amino alcohol complexes ewas not anticipated. Equally surprising was the transformation of a mononuclear starting material into a one-dimensional (1D) coordination polymer, [Cu(quin) 2 ] n (g). Spontaneous deprotonation of some amino alcohols and coordination of, thus formed, amino alcoholates via both donors also took place. Dinuclear complexes (d) contained two bridging amino alcoholates, whilst bidentate chelating mode was observed for type f. Interestingly, the dinuclear complex exists as two isomers which differ in the position of quinaldinates with respect to the Cu(m-OR) 2 Cu core. DFT calculations on isolated syn- and anti-[Cu 2 (quin) 2 (3a1pO) 2 ] (3a1pO  = anion of 3-amino-1-propanol) have shown the syn isomer to be more stable. The explanation lies in the intramolecular ppstacking of quinaldinates, possible only in this isomer. Magnetic susceptibility measurements revealed antiferromagnetic interactions between S= 1/2 copper(II) spins in all the studied compounds except in [Cu(quin) 2 ] n (g) for which weak ferromagnetic couplings are detected. 1. Introduction The last two decades have witnessed remarkable progress in crystal engineering. 1–3 As follows from its definition, the design of molecular solids with specific physical and chemical properties through understanding and control of intermolecular interactions, 4,5 crystal engineering encompasses many aspects of classical coordination chemistry. The choice of the metal ion is crucial as the metal performs a functional role of the solid material through its redox, magnetic and optical properties. Copper(II) is one of the frequently employed metal ions in crystal engineering because of its versatile coordination behavior, redox and catalytic properties. It has a d 9 electron configuration with geometric preferences based partly on LFSE (ligand field stabilization energy): it is normally coordinated by 4, 5 or 6 donors in square-planar, distorted square-pyramidal or, owing to Jahn–Teller distortion, axially distorted octahedral geometries. 6 All the above properties combined with lower toxicity than most 4d and 5d transition metals 7 make copper(II)awidespread ion in nature. It is present in active sites of many oxidation enzymes. 8 The involvement of copper ions in electron and oxygen transport exploits the easy interconversion between the +1 and +2 oxidation states. 9 Amino alcohols are a class of multidentate N,O-donor ligands that have also been used in crystal engineering. Both their a Faculty of Chemistry and Chemical Technology, University of Ljubljana, Vec ˇna pot 113, 1000 Ljubljana, Slovenia. E-mail: barbar[email protected] b Univ. Bordeaux, CNRS, Centre de Recherche Paul Pascal, UMR 5031, F-33600, Pessac, France c Instituto de Investigaciones Quı ´micas (IIQ), Departamento de Quı ´mica Inorga ´nica and Centro de Innovacio ´n en Quı ´mica Avanzada (ORFEO-CINQA), Consejo Superior de Investigaciones Cientı ´ficas (CSIC) and Universidad de Sevilla, Avenida Ame ´rico Vespucio 49, 41092 Sevilla, Spain †Electronic supplementary information (ESI) available: Powder X-ray diffraction patterns (Fig. S1), crystallographic data (Tables S1–S3), ORTEP drawings of 1a and syn-8d (Fig. S2 and S3), intermolecular interactions (Fig. S4–S19 and Tables S5–S13), additional geometric parameters (Tables S4 and S14), details on DFT calculations (Tables S15–S17), optimized geometries and infrared spectroscopy data (Tables S18–S19, Fig. S20–S44). CCDC 2076993–2077015. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/d2nj00296e Received 19th January 2022, Accepted 1st March 2022 DOI: 10.1039/d2nj00296e rsc.li/njc NJC PAPER Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online View Journal | View Issue 6900 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 functional groups, OH and NH 2 , are able to coordinate to transition metal ions. The OH moiety can give off its proton, producing anions which act as bridging and chelating ligands. Studies of copper(II)coordinationchemistry with amino alcohols have shown that the OH group frequently undergoes spontaneous 0deprotonation. 10 Another important characteristic of amino alcohols that makes them suitable for application in crystal engineering is their ability to participate in hydrogen bonding. The above listed properties combined with their commercial availability and low cost have strongly encouraged research on their coordination chemistry with transition metal ions including copper(II). 11 Studies with a number of aliphatic amino alcohols have been performed so far, e.g., 2-aminoethanol, 12 N,N0-di- methylethanolamine, 13 3-amino-1-propanol, 10,12,14–20 diethanolamine, 21–23 N-methyldiethanolamine, 24–26 N-butyldiethanolamine, 13 and triethanolamine. 27,28 A survey of the Cambridge Structural Database reveals that there are more complexes with amino alcoholate ions than with intact amino alcohols. 29 Arecent review describes the structural diversity of copper(II)amino alcoholate complexes. 30 The most common structural type encountered is Cu(m-OR) 2 Cu, a dinuclear core with copper(II) ions bridged by two amino alcoholate (  OR) oxygen atoms. Owing to their rigid behavior, the dinuclear cores served as building units in the construction of metal–organic frameworks (MOFs) 31,32 whose dimensionality was controlled through the denticity of the parent amino alcohol. 23 It is noteworthy that some copper(II) amino alcoholate complexes have found application in catalysis, 33 as exemplified by their catalytic role in the oxidative transformation of alkanes. 34–36 We reported recently on the reactions of zinc(II) quinaldinate with two amino alcohols, 3-amino-1-propanol and 2-methyl- aminoethanol. 37 Through the use of quinaldinate (abbreviated throughout the text as quin  ), the anionic form of quinaldinic acid (Scheme 1), which usually binds in a N,O-chelating manner and thereby occupies two binding sites in the metal’s coordination sphere, the possible reaction outcomes were highly limited. As a follow-up, zinc(II) was replaced with copper(II) which is known for its redox activity. Another reason for choosing copper(II) was that in spite of its radically different chemical behavior, copper(II) forms many homologous compounds to zinc(II). The study was expanded also by using a larger assortment of amino alcohols. Despite the recognized use of many amino alcohols, their combination with quinaldinate in copper(II) coordination chemistry has not been explored and no copper(II) compounds containing both ligands have been documented. The selected amino alcohols include primary amines (3-amino-1-propanol, 2-aminoethanol, 1-amino-2-propanol, 1-amino-2-methyl-2-propanol, 1-amino-2-butanol, 2-amino-1- propanol, 2-amino-2-methyl-1-propanol, 2-amino-1-butanol), secondary amines (2-methylaminoethanol and 2-ethylamino- ethanol) and a tertiary amine (2-dimethylaminoethanol). The latter three amino alcohols were chosen in order to explore the influence of an alkyl substituent on nitrogen atoms over their coordination behavior. The structural formulae of the used amino alcohols, their names and the abbreviations are given in Scheme 2. Herein, we report on the products of threecomponent copper(II)–quinaldinate–amino alcohol systems. Their detailed characterization by single-crystal X-ray diffraction analyses and infrared vibrational spectroscopy is presented. For convenience, the novel compounds are classified into seven structural types, labelled ato g(Scheme 3). Type a denotes trans-[Cu(quin) 2 L 2 ] (L = amino alcohol) complexes. Although type band cshare the same composition, [Cu(quin) 2 L], they differ in the amino alcohol binding mode and therefore in dimensionality. In a mononuclear type bcomplex, the amino alcohol adopts a bidentate chelating coordination mode, whereas in cwith an infinite chain structure the amino alcohol serves as a bidentate bridging ligand. A type ddinuclear complex with bridging amino alcoholates exists in two isomeric forms, syn and anti, which differ in the quinaldinate position with respect to the Cu(m-O) 2 Cu plane. Type ecompounds with the [CuL 3 ] 2+ formula are homoleptic amino alcohol complexes, whereas type fis a homoleptic amino alcoholate complex with a metal ion in a square-planar environment. Finally, type gis a homoleptic quinaldinate complex with an infinite chain structure. With the exception of type ccompounds, the magnetic properties were studied on at least one compound of each type. A correlation between their magnetic behavior and solid-state structures is presented. In addition, DFT calculations were performed on singlet and triplet states of syn-andanti-[Cu 2 (quin) 2 - (3a1pO) 2 ]. The calculations on selected 3a1pOH complexes were used to assess their stabilities. 2. Experimental General Acetonitrile, used as a solvent, was dried with molecular sieves. 38 Other reagents were purchased from commercial sources and used as received. The synthetic procedure for the starting material [Cu(quin) 2 (H 2 O)] was the same as described previously. 39 A Bruker Alpha II FT-IR spectrophotometer with an ATR module was used to record infrared spectra in the 4000– 400 cm 1 spectral range. No manipulations were made on the IR spectra. Powder X-ray diffraction (PXRD) patterns for aged anti-11d4MeOH were obtained using a PANanlytical X’Pert PRO MD diffractometer using monochromatised Cu-K a radiation (l= 1.5406 Å). A PerkinElmer 2400 II analyzer was used for elemental CHN analyses. Elemental analyses were not performed for 11a3a1pOH,11b,syn-11d,anti-11d4MeOH,anti- 11d2MeCN, and anti-11d2MeOH2(3a1pOH) for three different reasons. 11a3a1pOH,anti-11d4MeOH,anti-11d2MeCN, and anti-11d2MeOH2(3a1pOH) are solvates which are not stable outside of the mother liquor, 11b was obtained as a one-time event in a very small amount, whereas syn-11d was Scheme 1 Structural formula of quinoline-2-carboxylic acid, also known as quinaldinic acid. Paper NJC Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6901 obtained in a mixture with other compounds. All novel compounds except syn-9d and syn-10d were characterized by X-ray structure analysis on single-crystals. trans-[Cu(quin) 2 (2aeOH) 2 ] (1a) Procedure A. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-aminoethanol (1 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Green, needle-like crystals of trans- [Cu(quin) 2 (2aeOH) 2 ](1a) were filtered off. Yield: 41 mg, 66%. Procedure B. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-aminoethanol (1 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue crystalline precipitate was filtered off and air-dried. Yield: 53 mg, 85%. Please note that the same product formed at 4 1C. IR (ATR, cm 1 ): 3284s, 3156w, 3110w, 3087w, 3063w, 2971w, 2958m, 2859w, 2715w, 1604vs, 1587vs, 1562s, 1550s, 1505m, 1461s, 1430m, 1372vs, 1345s, 1301w, 1268w, 1254m, 1218m, 1206w, 1174s, 1152m, 1142w, 1117w, 1079s, 1034vvs, 1021s, 994w, 957m, 896m, 881m, 859s, 854s, 810s, 798s, 777vvs, 748s, 708s, 632s, 607vs, 601vvs, 576s, 548m, 522m, 494s, 482m, 443w, 413m. Elemental analysis calcd. for C 24 H 26 CuN 4 O 6 (%): C, 54.39; H, 4.94; N, 10.57. Found (%): C, 54.03; H, 4.73; N, 10.72. [Cu(quin) 2 (2maeOH)] (2b) Procedure A. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-methyl- aminoethanol (0.25 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Green crystals of [Cu(quin) 2 (2maeOH)] (2b) were filtered off. Yield: 50 mg, 88%. Procedure B.[Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-methylaminoethanol (0.25 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue crystalline solid was filtered off and air-dried. Yield: 51 mg, 90%. Please note that the same product formed at 4 1C. IR (ATR, cm 1 ): 3378w, 3211m, 3103w, 3054w, 3007w, 2970w, 2904w, 2850w, 1640s, 1594m, 1564m, 1509w, 1484w, 1461m, 1415w, 1362vs, 1343s, 1295m, 1268m, 1216m, 1183m, 1172m, 1150m, 1112w, 1094w, 1058m, 1029s, 979w, 969w, 958w, 899s, 877m, 850m, 800vs, 780vvs, 662m, 640m, 628s, 606s, 563w, 550m, 522m, 497s, 481m, 413m. Elemental analysis calcd for Scheme 2 Amino alcohols used in this study. NJC Paper Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online 6902 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 C 23 H 21 CuN 3 O 5 (%): C, 57.20; H, 4.38; N, 8.70. Found (%): C, 57.12; H, 4.21; N, 8.76. [Cu(quin) 2 ] n (g) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-dimethylaminoethanol (0.1 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Green crystals of [Cu(quin) 2 ] n (g) were filtered off and air-dried. Yield: 39 mg, 81%. Please note that the reaction without the amino alcohol yielded [Cu(quin) 2 ] n (g) with approximately the same yield. On prolonged standing in the solution, compound gconverted into a starting material, [Cu(quin) 2 (H 2 O)]. IR (ATR, cm 1 ): 3132w, 3102w, 3080w, 3051w, 3015w, 1637s, 1596m, 1567m, 1556m, 1510m, 1463m, 1436w, 1383s, 1372s, 1357s, 1274m, 1211m, 1202m, 1187m, 1148m, 1112w, 1026m, 1000w, 966m, 904m, 881m, 853s, 805vs, 767vvs, 741s, 735s, 641s, 633s, 611s, 576m, 522m, 493vs, 479m, 436s, 405s. Elemental analysis calcd for C 20 H 12 CuN 2 O 4 (%): C, 58.90; H, 2.97; N, 6.87. Found (%): C, 58.82; H, 2.93; N, 6.77. anti-[Cu 2 (quin) 2 (2eaeO) 2 ](anti-4d) Procedure A. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-ethylamino- ethanol (1 mL). The container was closed and inserted into a Scheme 3 Structural formulae of novel complexes. L denotes the amino alcohol ligand. Paper NJC Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6903 steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Green needle-like crystals of anti-[Cu 2 (quin) 2 (2eaeO) 2 ](anti-4d) were filtered off. Yield: 14 mg, 37%. Procedure B. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-ethylaminoethanol (0.5 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, green crystalline solid was filtered off and airdried. Yield: 34 mg, 89%. Please note that the same product formed at 4 1C. IR (ATR, cm 1 ): 3183m, 3061w, 2975w, 2938m, 2876m, 2833m, 1636vvs, 1595m, 1566m, 1507w, 1464m, 1432w, 1360vs, 1306w, 1262w, 1219m, 1173s, 1153m, 1137w, 1094m, 1062s, 1032s, 993w, 974w, 961w, 929w, 912m, 897m, 876m, 848s, 800s, 781vs, 775vs, 738w, 629s, 600s, 553m, 522w, 490m, 450s, 412s. Elemental analysis calcd for C 28 H 32 Cu 2 N 4 O 6 (%): C, 51.93; H, 4.98; N, 8.65. Found (%): C, 51.98; H, 4.88; N, 8.81. [Cu(1a2pOH) 3 ](quin) 2 (5e) Procedure A. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 1-amino-2- propanol (0.5 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Blue needle-like crystals of [Cu(1a2pOH) 3 ](quin) 2 (5e) were filtered off. Yield: 60 mg, 81%. Procedure B. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 1-amino-2-propanol (0.5 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue crystalline solid was filtered off and air-dried. Yield: 72 mg, 97%. Please note that the same product formed at 4 1C. IR (ATR, cm 1 ): 3236m, 3122m, 2971w, 2963w, 2927w, 2873w, 1829w, 1615s, 1595m, 1581s, 1553s, 1500m, 1462m, 1424m, 1380s, 1369vs, 1341s, 1300m, 1213w, 1199w, 1171s, 1145w, 1117s, 1108s, 1090s, 1079s, 1058m, 1026s, 993w, 956w, 925w, 912w, 890m, 876w, 856m, 832w, 809s, 777vvs, 739s, 707m, 644m, 627m, 595s, 565w, 548w, 535w, 520m, 500w, 485m, 476m, 408w. Elemental analysis calcd for C 29 H 39 CuN 5 O 7 (%): C, 55.01; H, 6.21; N, 11.06. Found (%): C, 54.96; H, 6.11; N, 11.11. trans-[Cu(quin) 2 (1a2m2pOH) 2 ] (6a) Procedure A. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 1-amino-2- methyl-2-propanol (0.25 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Blue needle-like crystals of trans-[Cu(quin) 2 (1a2m2pOH) 2 ](6a) were filtered off. Yield: 62 mg, 90%. Procedure B. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 1-amino-2-methyl-2- propanol (0.5 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue crystalline solid was filtered off and air-dried. Yield: 66 mg, 96%. Please note that the same product formed at 4 1C. IR (ATR, cm 1 ): 3323m, 3244w, 3148w, 3060w, 2974m, 2964w, 2933w, 1609s, 1587s, 1561s, 1548m, 1505m, 1461m, 1430w, 1404m, 1379s, 1369s, 1336s, 1265m, 1250m, 1217m, 1178s, 1142s, 1105s, 1037s, 1018m, 997m, 971m, 958m, 932w, 907m, 896s, 878m, 869m, 859m, 808s, 798s, 774vvs, 745s, 672m, 632vs, 601vs, 589s, 547m, 522m, 495m, 481m, 415w. Elemental analysis calcd for C 28 H 34 CuN 4 O 6 (%): C, 57.38; H, 5.85; N, 9.56. Found (%): C, 57.18; H, 5.78; N, 9.54. trans-[Cu(quin) 2 (1a2bOH) 2 ] (7a) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL), triethylamine (0.25 mL) and 1-amino-2-butanol (0.5 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Green needle-like crystals of trans-[Cu(quin) 2 (1a2bOH) 2 ](7a) were filtered off. Yield: 49 mg, 71%. IR (ATR, cm 1 ): 3431w, 3260m, 3166w, 3078w, 3061w, 2970w, 2957m, 2939w, 2874w, 1594s, 1562s, 1549s, 1506m, 1461s, 1430w, 1370s, 1343s, 1325s, 1281m, 1265m, 1216w, 1170s, 1151m, 1137m, 1115m, 1088m, 1075m, 1062m, 1033m, 986m, 961s, 897m, 879m, 859m, 840w, 802s, 774vvs, 742s, 707m, 632s, 601vs, 551m, 521m, 496s, 480m, 441w, 428w. Elemental analysis calcd for C 28 H 34 CuN 4 O 6 (%): C, 57.38; H, 5.85; N, 9.56. Found (%): C, 57.53; H, 5.74; N, 9.70. [Cu(1a2bOH) 3 ](quin) 2 (7e) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 1-amino-2-butanol (0.5 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue crystalline solid, [Cu(1a2bOH) 3 ](quin) 2 (7e), was filtered off and air-dried. Yield: 75 mg, 95%. Please note that the same product formed at 4 1C. IR (ATR, cm 1 ): 3263m, 3212m, 3139m, 2964m, 2933m, 2875m, 1836w, 1613s, 1594m, 1578m, 1550s, 1500m, 1462s, 1425m, 1383s, 1367vs, 1340s, 1312m, 1249w, 1215w, 1202w, 1170s, 1146w, 1110m, 1097m, 1053m, 1038s, 1019m, 981s, 955m, 919w, 890w, 881w, 856m, 809s, 779vvs, 743s, 700m, 645m, 627m, 594s, 556m, 548m, 521m, 498m, 478m, 459w, 430w. Elemental analysis calcd for C 32 H 45 CuN 5 O 7 (%): C, 56.92; H, 6.72; N, 10.37. Found (%): C, 56.53; H, 6.66; N, 10.48. Reactions with 2a1pOH (8) The reactions with 2-amino-1-propanol are not reproducible. Furthermore, mixtures of products can form. The procedures listed below yielded a certain product at least once. [Cu(quin) 2 (2a1pOH)] (8b) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-amino-1-propanol (0.15 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. Crystalline solid, [Cu(quin) 2 (2a1pOH)] (8b), was filtered off and air-dried. Yield: 46 mg, 81%. IR (ATR, cm 1 ): 3376w, 3343w, 3226w, 3140w, 3102w, 3056w, NJC Paper Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online 6904 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 3009w, 2957w, 2932w, 2877w, 1641s, 1592m, 1565m, 1512w, 1459s, 1429w, 1361vs, 1342s, 1297m, 1275w, 1264w, 1251w, 1217m, 1183m, 1173s, 1149m, 1114m, 1053s, 1039s, 969w, 958w, 919w, 899s, 883w, 850m, 842m, 800vs, 781vvs, 678m, 640m, 629s, 606s, 558m, 521m, 498s, 486m, 479m, 461w, 431m, 414m. Elemental analysis calcd for C 23 H 21 CuN 3 O 5 (%): C, 57.20; H, 4.38; N, 8.70. Found (%): C, 57.15; H, 4.23; N, 8.47. [Cu(quin) 2 (2a1pOH)] n (8c) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (6.5 mL), methanol (1 mL) and 2-amino-1-propanol (0.25 mL) were added to an Erlenmeyer flask. The mixture was stirred thoroughly until all the solid was consumed. The resulting blue solution was left to stand under ambient conditions. After a period of time, crystals of [Cu(quin) 2 (2a1pOH)] n (8c) and syn-[Cu 2 (quin) 2 - (2a1pO) 2 ](syn-8d) were obtained. IR (ATR, cm 1 ): 3302w, 3214w, 3133w, 3099w, 3052w, 2987w, 2973w, 2953w, 2907w, 2823w, 1641s, 1624s, 1592s, 1564m, 1505w, 1457m, 1427w, 1359s, 1341s, 1258m, 1252m, 1216m, 1169m, 1153m, 1141m, 1119m, 1076s, 1060s, 1021w, 964m, 955w, 917w, 897m, 880m, 852m, 801vs, 778vvs, 640s, 629s, 608s, 599s, 570m, 523m, 494m, 428s, 406m. Elemental analysis calcd for C 23 H 21 CuN 3 O 5 (%): C, 57.20; H, 4.38; N, 8.70. Found (%): C, 57.02; H, 4.19; N, 8.66. syn-[Cu 2 (quin) 2 (2a1pO) 2 ](syn-8d) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (6 mL), methanol (1.5 mL), triethylamine (0.25 mL) and 2-amino-1- propanol (0.25 mL) were added to an Erlenmeyer flask. The mixture was stirred thoroughly until all the solid was consumed. The resulting blue solution was left to stand under ambient conditions. After a period of time, a small amount of crystals of syn-[Cu 2 (quin) 2 (2a1pO) 2 ](syn-8d) was obtained. IR (ATR, cm 1 ): 3323w, 3251s, 3145m, 3066w, 3050w, 2955m, 2917m, 2875m, 2841w, 2804w, 2711w, 1635vvs, 1596m, 1567s, 1556m, 1508m, 1462m, 1431w, 1352vs, 1304m, 1276m, 1262w, 1216w, 1204w, 1175s, 1148m, 1116m, 1070s, 1047s, 1020m, 966m, 955w, 938w, 922w, 896m, 876m, 853s, 801vs, 771vvs, 742s, 716s, 661w, 634s, 626m, 603s, 574m, 556m, 535m, 521m, 495s, 457s, 428s. Elemental analysis calcd for C 26 H 28 Cu 2 N 4 O 6 (%): C, 50.40; H, 4.56; N, 9.04. Found (%): C, 50.28; H, 4.56; N, 8.94. [Cu(2a1pOH) 3 ](quin) 2 (8e) Procedure A. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-amino-1-propanol (0.25 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue crystalline solid, [Cu(2a1pOH) 3 ](quin) 2 (8e), was filtered off and airdried. Yield: 58 mg, 78%. Procedure B. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-amino-1-propanol (0.5 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was stored at 4 1C. Crystals of 8e were filtered off after a few days. Yield: 46 mg, 62%. IR (ATR, cm 1 ): 3213m, 3123m, 2962w, 2926w, 2881w, 1835w, 1606s, 1557s, 1500m, 1460m, 1424m, 1365vs, 1337s, 1296m, 1245w, 1212m, 1199w, 1167m, 1143w, 1109s, 1070m, 1043s, 989w, 955m, 919w, 890m, 878m, 855m, 838w, 806s, 778vvs, 740s, 680m, 656m, 627s, 593s, 552m, 521m, 476m, 455m, 406w. Elemental analysis calcd for C 29 H 39 CuN 5 O 7 (%): C, 55.01; H, 6.21; N, 11.06. Found (%): C, 54.78; H, 6.12; N, 10.73. syn-[Cu 2 (quin) 2 (2a2m1pO) 2 ](syn-9d) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (6 mL), methanol (1.5 mL) and 2-amino-2-methyl-1-propanol (0.5 mL) were added to an Erlenmeyer flask. The mixture was stirred thoroughly until all the solid was consumed. The resulting blue solution was left to stand under ambient conditions. After a few days, a small amount of crystalline syn-[Cu 2 (quin) 2 (2a2m1pO) 2 ] (syn-9d) was obtained. IR (ATR, cm 1 ): 3255m, 3145m, 3060w, 2971w, 2951w, 2905w, 2871w, 2835w, 1638vvs, 1597m, 1567m, 1506w, 1462m, 1361vs, 1302w, 1255w, 1231m, 1188m, 1172m, 1148m, 1129m, 1068m, 1047s, 1019m, 983m, 958w, 924w, 897m, 875w, 853s, 804s, 772vs, 738m, 707m, 627s, 602m, 545m, 522m, 499m, 444s, 413s. Elemental analysis calcd for C 28 H 32 Cu 2 N 4 O 6 (%): C, 51.93; H, 4.98; N, 8.65. Found (%): C, 51.89; H, 5.06; N, 8.88. [Cu(2a2m1pO) 2 ](2a2m1pOHH) 2 (quin) 2 (9f) Procedure A. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-amino-2-methyl-1-propanol (0.5 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, a mixture of blue crystalline solid, syn-9d, and colorless needle-like crystals of 2a2m1pOHH + guin  (2a2m1pOHH + = a cationic form of 2-amino-2-methyl-1-propanol with a NH 3+ moiety) was obtained. 2a2m1pOHH + quin  crystallized in two polymorphic modifications. After a few days, only purple crystals of [Cu(2a2m1pO) 2 ]- (2a2m1pOHH) 2 (quin) 2 (9f)wereleftintheflask.Thepurplesolid was filtered off. Yield: 83 mg, 92%. Procedure B. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (6 mL), methanol (1.5 mL) and 2-amino-2-methyl-1-propanol (0.5 mL). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. After a few days, purple crystals of 9f grew from the solution. Yield: 73 mg, 81%. IR (ATR, cm 1 ): 3315m, 3213w, 3076m, 2982m, 2957m, 2869m, 2845m, 2792m, 2743m, 2610m, 2550m, 2512m, 2110w, 1644m, 1602s, 1582s, 1553s, 1501m, 1471m, 1464m, 1423w, 1384s, 1372vs, 1326w, 1297w, 1275m, 1260w, 1222w, 1211w, 1190m, 1169m, 1147m, 1100w, 1055vvs, 1010s, 984m, 975m, 954w, 928w, 913w, 903w, 890m, 870w, 852m, 802s, 786vvs, 775vvs, 738m, 690m, 637w, 626s, 608s, 593m, 564w, 521m, 474s, 458s, Paper NJC Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6905 442s, 422m. Elemental analysis calcd for C 36 H 56 CuN 6 O 8 (%): C, 56.56; H, 7.38; N, 10.99. Found (%): C, 56.50; H, 7.43; N, 10.98. syn-[Cu 2 (quin) 2 (2a1bO) 2 ](syn-10d) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 2-amino-1-butanol (0.25 mL) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, a small amount of crystalline solid, syn-[Cu 2 (quin) 2 (2a1bO) 2 ](syn-10d), was filtered off and air-dried. Note. On prolonged standing in solution, the salt, 2a1bOHH + quin  (2a1bOHH + = a cationic form of 2-amino-1- butanol with a NH 3+ moiety), precipitated. 2a1bOHH + quin  crystallized in two polymorphic modifications. IR (ATR, cm 1 ): 3255s, 3143m, 3051w, 2965m, 2920m, 2896m, 2880m, 2837m, 2806w, 2701w, 1636vvs, 1594m, 1567s, 1506m, 1460s, 1351vs, 1261w, 1214w, 1172s, 1147m, 1128m, 1105m, 1075s, 1019m, 987m, 964m, 954w, 930w, 896m, 874m, 867w, 851s, 801s, 770vs, 739s, 719s, 634s, 602s, 555m, 538m, 521m, 493s, 467m, 434s. Elemental analysis calcd for C 28 H 32 Cu 2 N 4 O 6 (%): C, 51.93; H, 4.98; N, 8.65. Found (%): C, 51.31; H, 4.58; N, 8.70. [Cu(2a1bOH) 3 ](quin) 2 (10e) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (6 mL), methanol (1.5 mL) and 2-amino-1-butanol (0.5 mL) were added to an Erlenmeyer flask. The mixture was stirred thoroughly until all the solid was consumed. The resulting blue solution was left to stand under ambient conditions. On the following day, the solution was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. Typically, a mixture of blue crystals of [Cu(2a1bOH) 3 ](quin) 2 (10e), syn-10d and/or 2a1bOHH + quin  was obtained. IR (ATR, cm 1 ): 3218m, 3125m, 2963m, 2934m, 2877w, 1840w, 1594s, 1557s, 1500m, 1460s, 1423m, 1366vs, 1337s, 1247w, 1211w, 1199w, 1167s, 1144m, 1108m, 1095m, 1044vs, 997m, 953m, 922w, 889m, 880m, 854s, 806s, 778vvs, 741s, 626s, 591s, 550w, 521m, 486m, 477m, 437w. Elemental analysis calcd for C 32 H 45 CuN 5 O 7 (%): C, 56.92; H, 6.72; N, 10.37. Found (%): C, 56.74; H, 6.74; N, 10.21. trans-[Cu(quin) 2 (3a1pOH) 2 ] (11a) [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 3-amino-1-propanol (150 mg) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. On the following day, blue needle-like crystals of trans-[Cu(quin) 2 (3a1pOH) 2 ](11a) were filtered off. Yield: 58 mg, 89%. IR (ATR, cm 1 ): 3384m, 3329m, 3224m, 3052w, 2959w, 2943w, 2914w, 2869w, 2858w, 2815w, 1623s, 1595m, 1559m, 1548m, 1504w, 1480w, 1459m, 1432m, 1408w, 1385s, 1371vs, 1342s, 1263m, 1213m, 1174m, 1161m, 1146m, 1051s, 1030m, 1021m, 995s, 983m, 961m, 899s, 875w, 855m, 810s, 802s, 773vvs, 738s, 629vs, 618s, 600s, 560m, 520s, 495s, 476m, 458m. Elemental analysis calcd for C 26 H 30 CuN 4 O 6 (%): C, 55.96; H, 5.42; N, 10.04. Found (%): C, 55.68; H, 5.23; N, 10.11. trans-[Cu(quin) 2 (3a1pOH) 2 ]3a1pOH (11a3a1pOH) [Cu(quin) 2 (H 2 O)] (25 mg, 0.06 mmol) and acetonitrile (7.5 mL) were added to an Erlenmeyer flask. After the contents were cooled to 4 1C, 3-amino-1-propanol (150 mg) was added. The reaction mixture was left to stand in a closed vessel at 4 1C for approximately 1 hour. Afterwards, blue crystalline solid, trans- [Cu(quin) 2 (3a1pOH) 2 ]3a1pOH (11a3a1pOH), was filtered off. Yield: 29 mg. Please note that owing to the solvent molecules of 3a1pOH, the crystals of 11a3a1pOH are not stable when taken out from the mother liquor. In the solution, 11a3a1pOH converts into 11a within a day. IR (ATR, cm 1 ): 3359w, 3255m, 3175m, 3050w, 2950w, 2867w, 1634s, 1614s, 1588s, 1562s, 1504m, 1486w, 1462m, 1427w, 1391s, 1377s, 1359s, 1344s, 1299w, 1268w, 1215w, 1168m, 1153m, 1147m, 1109w, 1060s, 1044s, 1017m, 993m, 955w, 931m, 894s, 855m, 849m, 801vs, 775vvs, 745m, 672m, 630s, 599s, 550m, 521m, 500m, 482w. [Cu(quin) 2 (3a1pOH)] (11b) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 3-amino-1-propanol (150 mg). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was transferred to an Erlenmeyer flask which was left open for 1 day. Afterwards, the flask was stoppered. Within 24 hours, crystals of [Cu(quin) 2 (3a1pOH)] (11b) grew from the oil. Please note that 11b was obtained as a one-time event, otherwise 11a, 11a3a1pOH or anti-11d2MeCN formed. IR (ATR, cm 1 ): 3345m, 3233m, 3154m, 3104w, 3056w, 3011w, 2985w, 2943w, 2917w, 2879w, 1641s, 1594s, 1564s, 1506m, 1458s, 1435w, 1416w, 1362vs, 1342s, 1295m, 1259m, 1242m, 1217m, 1183m, 1173s, 1151m, 1112s, 1093m, 1046m, 1024w, 975s, 958m, 946s, 899s, 881m, 851s, 833w, 799s, 782vvs, 661s, 640s, 633s, 627s, 606s, 555m, 521s, 497s, 478m. [Cu(quin) 2 (3a1pOH)] n (11c) anti-[Cu 2 (quin) 2 (3a1pO) 2 ]4MeOH (50 mg), acetonitrile (6 mL), methanol (1.5 mL), quinaldinic acid (28 mg) and 3-amino-1- propanol (24 mg) were added to an Erlenmeyer flask. The contents were stirred at room temperature for 1 day. All the solid was consumed meanwhile. The resulting blue solution was stored at 4 1C for a few days. Crystals of [Cu(quin) 2 - (3a1pOH)] n (11c) were filtered off and air-dried. Yield: 22 mg. IR (ATR, cm 1 ): 3335w, 3238w, 3154w, 3095w, 3071w, 2953w, 2928w, 2886w, 1644s, 1628s, 1598s, 1564m, 1506w, 1475w, 1460s, 1446w, 1360vs, 1343s, 1295w, 1257m, 1237w, 1217w, 1197w, 1180m, 1172m, 1154m, 1139m, 1081m, 1066s, 1034m, 994w, 963w, 956w, 901m, 881m, 858m, 816m, 803vs, 775vvs, 750m, 640m, 630m, 608s, 600m, 569w, 548w, 530w, 521m, 499m, 431m, 405m. Elemental analysis calcd for C 23 H 21 CuN 3 O 5 (%): C, 57.20; H, 4.38; N, 8.70. Found (%): C, 57.18; H, 4.30; N, 8.16. NJC Paper Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online 6906 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 syn-[Cu 2 (quin) 2 (3a1pO) 2 ](syn-11d) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL) and 3-amino-1-propanol (150 mg). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. After a period of time, crystals of syn-[Cu 2 (quin) 2 (3a1pO) 2 ](syn-11d) and 11a deposited from the concentrate. Please note that syn-11d was obtained only once. syn-[Cu 2 (quin) 2 (3a1pO) 2 ]2H 2 O(syn-11d2H 2 O) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), methanol (7.5 mL), triethylamine (0.5 mL) and 3-amino-1-propanol (150 mg). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. After a period of time, crystals of syn-[Cu 2 (quin) 2 (3a1pO) 2 ]2H 2 O(syn- 11d2H 2 O), syn-11d and 11a deposited from the concentrate. Please note that a more reliable way of preparing syn-11d2H 2 O proved to be by powdering a sample of anti-11d4MeOH. The powdered material was left to stand in the air for at least 1 day. IR (ATR, cm 1 ): 3469m, 3271m, 3160m, 3058w, 2936w, 2906w, 2885w, 2806m, 2698w, 1633vs, 1615vs, 1594s, 1563s, 1506m, 1460s, 1429w, 1372vs, 1343s, 1328m, 1306w, 1277w, 1260w, 1215w, 1180s, 1172s, 1148m, 1106w, 1085s, 1055s, 1017w, 985w, 956w, 932s, 896m, 883w, 877m, 852m, 802s, 778vvs, 741m, 718m, 658m, 642m, 633m, 596s, 520s, 494s, 450s. Elemental analysis calcd for C 26 H 32 Cu 2 N 4 O 8 (%): C, 47.63; H, 4.92; N, 8.55. Found (%): C, 47.54; H, 4.72; N, 8.16. anti-[Cu 2 (quin) 2 (3a1pO) 2 ]2MeCN (anti-11d2MeCN) Procedure A. [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (6 mL) and methanol (1.5 mL) were added to an Erlenmeyer flask. After, the contents were cooled to 4 1C, 3-amino-1- propanol (150 mg) was added. The reaction mixture was left to stand in a closed vessel at 4 1C. Blue-green crystals of anti- [Cu 2 (quin) 2 (3a1pO) 2 ]2MeCN (anti-11d2MeCN) were obtained after a few days. Procedure B. A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), acetonitrile (7.5 mL), triethylamine (0.5 mL) and 3-amino-1-propanol (150 mg). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was concentrated under reduced pressure on a rotary evaporator. The concentrate was transferred to an Erlenmeyer flask and left to stand under ambient conditions. Crystals of anti-11d2MeCN were obtained after few days. Please note that crystals of anti-11d2MeCN are not stable when taken out from the mother liquor. IR (ATR, cm 1 ): 3310m, 3219w, 3141w, 3056w, 3023w, 2983w, 2931w, 2876m, 2823w, 2708w, 2249w, 1630vs, 1619s, 1593m, 1560s, 1507m, 1461m, 1430m, 1397w, 1359vs, 1343s, 1301m, 1275m, 1260m, 1213w, 1178m, 1149s, 1112w, 1082s, 1059s, 1041m, 1021w, 969w, 956w, 930s, 885s, 858w, 821w, 811m, 779vvs, 745s, 684m, 641m, 633m, 596s, 521m, 501m, 486m, 434m, 407m. anti-[Cu 2 (quin) 2 (3a1pO) 2 ]4MeOH (anti-11d4MeOH) [Cu(quin) 2 (H 2 O)] (200 mg, 0.47 mmol), methanol (7.5 mL) and 3-amino-1-propanol (300 mg) were added to an Erlenmeyer flask. The flask was closed and left to stand under ambient conditions. After a few minutes, all the solid was consumed and the solution acquired a green color. Large, dark blue crystals of anti-[Cu 2 (quin) 2 (3a1pO) 2 ]4MeOH (anti-11d4MeOH) grew overnight. Yield: 141 mg. Please note that the crystals of anti- 11d4MeOH are not stable when removed from the mother liquor. In the air, they are converted into syn-11d2H 2 O.IR (ATR, cm 1 ): 3332w, 3264m, 3237m, 3151m, 3068w, 2921m, 2874m, 2851w, 2721w, 1632s, 1619s, 1594m, 1562m, 1507m, 1459m, 1430m, 1404w, 1359s, 1342s, 1302w, 1287w, 1261m, 1212w, 1177m, 1167s, 1149m, 1113w, 1086s, 1063s, 1022vs, 971w, 954w, 928s, 891m, 885s, 857w, 820w, 810m, 779vvs, 742s, 703m, 641s, 632s, 595s, 553m, 522s, 503s, 489s, 438s, 408m. Monitoring the conversion of anti-11d4MeOH into syn-11d 2H 2 O with IR spectroscopy Few, freshly prepared crystals of anti-11d4MeOH were placed in an ATR sample holder. At the start of the experiment, the spectra were collected every 5 minutes. The last spectrum was recorded after 24 hours. The spectra are shown in the ESI† (Fig. S20). The identity of the product was confirmed by PXRD (Fig. S1, ESI†). Reaction of anti-[Cu 2 (quin) 2 (3a1pO) 2 ]4MeOH with 3a1pOH anti-11d4MeOH (50 mg) was stirred in acetonitrile (7.5 mL) with quinaldinic acid (28 mg) and 3a1pOH (33 mg) at room temperature for 2 days. Crystalline 11a was filtered off. Yield: 60 mg. anti-[Cu 2 (quin) 2 (3a1pO) 2 ]2MeOH2(3a1pOH) (anti-11d2MeOH2(3a1pOH)) A Teflon container was filled with [Cu(quin) 2 (H 2 O)] (50 mg, 0.12 mmol), methanol (7.5 mL) and 3-amino-1-propanol (150 mg). The container was closed and inserted into a steel autoclave, which was heated for 24 hours at 105 1C. Afterwards, the autoclave was taken out from the oven and left overnight to cool to room temperature. The resulting green solution was concentrated under reduced pressure on a rotary evaporator. A glass vial with diethyl ether was carefully inserted into the Erlenmeyer flask with the concentrate. After a period of time, crystals of anti-11d2MeOH2(3a1pOH) grew from the concentrate. Please note that the crystals of anti-11d2MeOH2(3a1pOH) are not stable when taken out from the mother liquor. They were obtained only once. IR (ATR, cm 1 ): 3386w, 3341m, 3330m, 3271m, 3227m, Paper NJC Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6907 3152w, 3057w, 2927m, 2902w, 2866m, 2823w, 1628vs, 1593s, 1560s, 1505w, 1459m, 1431m, 1365vs, 1343s, 1304w, 1280w, 1262m, 1212w, 1167m, 1147m, 1113w, 1085m, 1051s, 995s, 983m, 958m, 933m, 899m, 893m, 885m, 855m, 810s, 803s, 793m, 774vvs, 738s, 705m, 640m, 630s, 619s, 597s, 560m, 520m, 495s, 458m, 436m. X-ray structure analysis Single crystal X-ray diffraction data were recorded using an Agilent SuperNova diffractometer with molybdenum (Mo-K a , l= 0.71073 Å) or copper (Cu-K a ,l= 1.54184 Å) micro-focus sealed X-ray source at 150 K. The diffractometer was equipped with mirror optics and an Atlas detector. Silicone grease was used to place each crystal on a fiber glass tip, which was then mounted on the goniometer head. Data were processed using CrysAlis PRO. 40 Structures were solved with Olex 2 software 41 using intrinsic phasing in ShelXT 42 and refined with the least squares methods in ShelXL. 43 Anisotropic displacement parameters were determined for all non-hydrogen atoms. Where possible, NH 2 , NH, NH 3+ and OH hydrogen atoms of amino alcohols were located from a difference Fourier map and refined with isotropic displacement parameters. OH hydrogen atoms of water and methanol in anti-11d4MeOH,syn-11d2H 2 O and anti-11d2MeOH2(3a1pOH) were located from a difference Fourier map. In some structures, the hydrogen atoms of amino alcohol heteroatoms were added in calculated positions due to ligand disorder (7a,8c,11b and 11c), large number of atoms in the asymmetric unit (8e and 10e) or a poor-quality data set (syn- 8d). The remaining hydrogen atoms were placed in geometrically calculated positions in all structures and refined using riding models. Disorder was observed for amino alcohol ligands in 2b, 5e,7a,7e,8c,8e,10e,11b and 11c.For2b,thedisorderoveratwofold rotation axis pertains also to copper(II) ion. For all, the disorder was resolved using the appropriate PART instruction. The programs Platon, 44 Ortep 45 and Mercury 46 were used for crystal structure analysis and the preparation of figures. The crystallographic data are collected in Tables S1–S3 (ESI†). All crystal structures were deposited at the CCDC and were assigned deposition numbers 2076993 (1a), 2076994 (2b), 2076995 (g), 2076996 (anti-4d), 2076997 (5e), 2076998 (6a), 2076999 (7a), 2077000 (7e), 2077001 (8b), 2077002 (8c), 2077003 (syn-8d), 2077004 (8e), 2077005 (9f), 2077006 (10e), 2077007 (11a), 2077008 (11a3a1pOH), 2077009 (11b), 2077010 (11c), 2077011 (syn-11d), 2077012 (syn-11d2H 2 O), 2077013 (anti-11d2MeCN), 2077014 (anti-11d4MeOH), and 2077015 (anti-11d2MeOH 2(3a1pOH)). Computational details Geometries of copper(II) complexes were optimized without constraints from X-ray diffraction data, using the Gaussian 09 software. 47 Coordinates of complex molecules of 11a,11b,syn- 11d2H 2 Oand anti-11d2MeCN were used. The initial geometry of 11a–L was derived from a repeating unit of 1D-polymer 11c. Vibrational analysis confirmed the nature of these structures as minima in the potential energy surface and was also used to obtain Zero Point and Gibbs free energies. The basis set 6-31+g(d,p) 48,49 including diffusion and polarization was used for all atoms, except for Cu, which was described by means of the SDD basis and the associated electron core potential (ECP). 50 The B3PW91 51–53 functional with the D3 version of Grimme’s dispersion with Becke–Johnson damping 54 was used. Bulk solvent effects (acetonitrile) were included during optimization with the SMD continuum model. 55 Relative energies of the triplet and antiferromagnetically coupled singlet states were assessed for the syn and anti isomers of [Cu 2 (quin) 2 - (3a1pO) 2 ] and the stabilities of the corresponding DFT wavefunctions were tested. 56,57 Typically, RHF to UHF instabilities were found for wave functions obtained from spin-restricted (singlet) wavefunctions. When a more stable, spin-unrestricted, wavefunction was located, it was used as the initial guess for subsequent geometry optimization. Analysis of the electron density within the Atoms In Molecules (AIM) theory of R. F. W. Bader 58 was performed with the Multiwfn program, 59,60 which was also used for Non-Covalent Interaction (NCI) Analysis. 61 The Cylview visualization software 62 was used to prepare some of the figures. Magnetic measurements All stable compounds, that could be obtained in pure form and in sufficient quantities, were subjected to magnetic susceptibility measurements using a MPMS-XL Quantum Design SQUID magnetometer which works between 1.8 and 400 K for dc applied fields ranging from 7 to 7 T. Measurements were performed on analytically pure polycrystalline samples (25.91, 21.40, 22.34, 14.12, 19.13, 23.15, 20.09, 19.97, 20.34, 23.75, 18.15 and 18.30 mg for 1a,2b,anti-4d,5e,6a,7a,7e,8e,9f, 11a,syn-11d2H 2 O, and g, respectively) introduced in polyethylene bags (3 0.5 0.02 cm, weighing typically between 7 and 19 mg). Prior to the experiments, a M vs. H measurement was performed at 100 K to confirm the absence of ferromagnetic impurities. Consistent dc susceptibility and in-phase ac susceptibility have been obtained between 1.85 and 15 K. The data were corrected for the sample holder and the diamagnetic contribution of the sample. 3. Results and discussion 3.1. Synthetic considerations In this study, a total of eleven different amino alcohols was reacted with the [Cu(quin) 2 (H 2 O)] precursor. The studied systems yielded six types of compounds, labelled ato f, which contained both the quinaldinate and the amino alcohol ligand. A homoleptic quinaldinate complex [Cu(quin) 2 ] n , labelled g, was also obtained. All the novel products are listed in Scheme 4. The product abbreviation consists of a number which represents the amino alcohol and a letter which represents the compound type. Typically, a large excess of amino alcohol was used in the reaction. Such a ligand-to-metal ion ratio favors the formation of a complex with the maximum number of ligands. In our case, trans-[Cu(quin) 2 L 2 ], a type acomplex with two amino NJC Paper Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online 6914 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 with ppstacking interactions between the layers. In the structure of g, infinite chains pack in a parallel fashion: each chain is surrounded by six others. ppstacking interactions occur within the same chain. No classical hydrogen bonds may be observed. 3.4. Relative stability of the 3a1pOH monomers As the 3-amino-1-propanol ligand produces the richest system in terms of the isolated species, two mononuclear complexes, trans-[Cu(quin) 2 (3a1pOH) 2 ](11a) and [Cu(quin) 2 (3a1pOH)] (11b), were optimized by DFT methods in bulk acetonitrile in order to assess their relative stabilities. The choice of 11a was governed by its reproducible formation under very diverse conditions. On the other hand, the difficulties experienced during the isolation of the two mono amino alcohol compounds, 11b and 11c, implied their nature to be very labile. The calculations indeed show 11a to be the most stable mononuclear species in this system. Furthermore, they indicate that the formal extrusion of one 3ap1OH ligand from trans- [Cu(quin) 2 (3a1pOH) 2 ](11a) to yield [Cu(quin) 2 (3a1pOH)] (11b) with the remaining amino alcohol bound in a bidentate chelating manner is slightly exergonic (by ca. 1 kcal mol 1 ; see Table S15 for details, ESI†). The process can be considered to occur through a five-coordinate species, labelled 11a–L. The latter was derived from a repeating unit of the 1D-polymer 11c. The calculations show 11a–L and 3ap1OH to be almost isoenergetic with 11a. The results on the relative stabilities of 11a,11a–L and 11b merit further comment since the calculated free energy differences point towards exclusive formation of 11a–L in the solution. The free energy variations were calculated at 1 atm for all species and intermolecular interactions in solution were not considered. However, the entropy term more than compensates for the energy required for the dissociation of one 3a1pOH ligand from 11a. Nevertheless, the energy variations calculated for the interconversion of the above species can be regarded as small enough and as such consistent with their facile interconversion in solution. As for the greater calculated stability of 11a–L vs. 11b,it must be noted that both species are almost isoenergetic when zero-point energies are compared. However, there is an entropy penalty related to the formation of the chelate 11b, which is counterbalanced by the energy released in the formation of a Cu–OH bond. This bond is significantly longer (by ca. 0.5 Å) than the other two Cu–O bonds, and the same is true for the Cu–N bond trans to it. The elongation of both bonds is attributable to the Jahn–Teller distortion. Accordingly, the Atom in Molecules (AIM) analysis 58 of the calculated electron density reveals electron densities at the bond critical points of these elongated bonds that are ca. 0.03 a.u., compared to the electron densities at the bond critical points for the remaining coordination bonds, which are in the range of 0.06–0.08 a.u. The calculated structures of 11b and 11a–L feature marked deviations from their respective ideal octahedral or square pyramid coordination environments (and from the initial X-ray geometries) caused by intramolecular ppstacking of quinaldinates (Fig. 10). In the crystal lattice of 11b, intermolecular ppstacking may be observed instead. 3.5. Magnetic properties The magnetic properties of a series of copper(II) complexes were studied by dc susceptibility measurements between 300 and 1.85 K. The mononuclear compounds, which were measured are [Cu(quin) 2 (2aeOH) 2 ](1a), [Cu(quin) 2 (1a2m2pOH) 2 ](6a), [Cu(quin) 2 (1a2bOH) 2 ](7a)[Cu(quin) 2 (3a1pOH) 2 ](11a), [Cu(quin) 2 (2maeOH)] (2b), [Cu(1a2pOH) 3 ](quin) 2 (5e), [Cu(1a2bOH) 3 ](quin) 2 (7e), [Cu(2a1pOH) 3 ](quin) 2 (8e)and [Cu(2a2m1pO) 2 ](2a2m1pOHH) 2 (quin) 2 (9f). Their room temperature wTproduct values fall within the 0.38 to 0.43 cm 3 Kmol 1 interval and are consistent with the presence of one S= 1/2 Cu(II) center with gvalues ranging from 2.03(5) to 2.15(5). Furthermore, the series of a,b,eand fcompounds displays a very similar temperature dependence of wTproducts (Fig. 11, top part). On lowering the temperature, the wTvalue remains constant at first, whereas at low temperatures, it decreases in a Fig. 9 The NCI plot showing intramolecular ppinteractions in syn- [Cu 2 (quin) 2 (3a1pO) 2 ] with blue and red regions representing repulsive and attractive weak interactions, respectively. Intermediate, weak noncovalent interactions are shown in green. Fig. 10 DFT-optimized geometries of 11b (left) and 11a–L (right). trans-[Cu(quin) 2 (3a1pOH) 2 ](11a)-[Cu(quin) 2 (3a1pOH)] (11a–L) + 3a1pOH 11a–L -11b Paper NJC Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6915 more or less pronounced manner. Such a behavior is an indication of weak or very weak intermolecular antiferromagnetic (AF) interactions. The solid-state structures of type acompounds are characterized by a hydrogen bonded one-dimensional arrangement with short Cu–OHN–Cu contacts (Fig. S4, S5 and Table S5, ESI†). Since the strongest magnetic interaction was expected to be mediated through these contacts, the magnetic susceptibility was modeled using the regular antiferromagnetic quantum S= 1/2 spin chain model with the following spin Hamiltonian, H¼2JP i ~ Si~ Siþ1;and the analytical susceptibility of Bonner–Fisher. 67–69 As shown in Fig. 11, the magnetic data for 1a,6a,7a and 11a are well-reproduced through the whole temperature range with this approach, leading to J/k B = 2.6(1) K and g= 2.10(5) for 1a,J/k B =1.4(1) K and g= 2.15(5) for 6a,J/k B =2.8(1) K and g= 2.15(5) for 7a, and J/k B = 1.75(4) K and g= 2.13(5) for 11a. In 2b,5e,7e,8e and 9f, the mononuclear compounds of types b,eand f, the observed supramolecular contacts and possible magnetic pathways are much weaker and involve more than three atoms between spin carriers. Similarly to type a compounds, a supramolecular chain organization is observed for 2b,5e,7e and 8e (Fig. S7 and S16, ESI†). The shortest CuCu contacts in 2b are 7.0950(2) Å and the ones in type e compounds are in the 6.5514(6)–6.8633(7) Å range. The magnetic susceptibility for 2b,5e,7e and 8e was modeled by applying the regular antiferromagnetic quantum S= 1/2 spin chain model 67–69 which reproduces very well the experimental data (Fig. 11, top part). The corresponding magnetic parameters are J/k B =0.21(5) K and g= 2.13(5) for 2b,J/k B = 0.14(3) K and g= 2.06(5) for 5e,J/k B =0.24(5) K and g= 2.03(5) for 7e, and J/k B =0.14(2) K and g= 2.04(5) for 8e. The magnetic interactions in these compounds are about 10 times smaller than in type acompounds. In the case of 9f, owing to the co-crystallization of 2a2m1pOHH + and quin  ions, the mononuclear [Cu(2a2m1pO) 2 ] complex molecules are wellseparated, as shown by the shortest CuCu contacts which exceed 8.1133(4) Å. Therefore, it is difficult to imagine any significant magnetic interactions. Magnetic interactions of 0.01(1) K were thus estimated from the mean field theory (with 4 next-neighbours) and the Weiss constant of –0.02 K, obtained from the Curie–Weiss fit of the experimental data. It should be underlined that the efficient separation of the [Cu(2a2m1pO) 2 ] complex molecules in 9f leads to virtually magnetically isolated S= 1/2 Cu(II) spins. The magnetic properties of the dinuclear Cu(II) complexes, anti-[Cu 2 (quin) 2 (2eaeO) 2 ](anti-4d) and syn-[Cu 2 (quin) 2 (3a1- pO) 2 ]2H 2 O(syn-11d2H 2 O), were also studied in the 1.85–300 K Fig. 11 The temperature dependence of the wTproduct (where wis the molar magnetic susceptibility that equals M/Hper compound, and Tis the temperature), collected at a dc magnetic field of 0.1 T for 1a,6a,7a,11a and 2b (top left), 5e,7e,8e and 9f (top right), anti-4d and syn-11d2H 2 O(bottom left), and g(bottom right). Insets: Semi-logarithm wT vs. T plots emphasizing the magnetic data at low temperatures. The solid lines are the best fits to the models described in the text. NJC Paper Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online 6916 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 temperature range (Fig. 11). In both, a pair of Cu(II)sitesis bridged by two alkoxide oxygens. It has been well-documented in the literature 70–74 that in this type of complexes the nature and magnitude of the magnetic interaction between the S=1/2Cu spins depend strongly on subtle differences in the geometry of the Cu(m-OR) 2 Cu moiety. The Cu–(m-O)–Cu angle (y) was identified as the primary factor: for angles smaller than 95.71, ferromagnetic couplings are expected, while antiferromagnetic ones are observedforlargerangles. 70–74 Other geometric factors, such as the planarity of the Cu 2 (m-O) 2 moiety and the out-of-plane shift of the carbon atom of the bridging alkoxide, known as t, usually add minor corrections to the main effect of the yangle. It was also shown that small values of yare associated with larger values of t. In syn-11d2H 2 Owith ybeing 103.25(8) and 103.85(8)1and t being 3.85(17) and 3.99(16)1, a strong AF interaction is expected, while a weaker one is likely for anti-4d with y= 100.09(9)1and t= 38.0(2)1.TheroomtemperaturewTvalue, 0.089 cm 3 Kmol 1 for syn-11d2H 2 Oand 0.66 cm 3 Kmol 1 for anti-4d,islowerthan the one expected for two magnetically isolated S= 1/2 spins (0.75 cm 3 Kmol 1 ), confirming the presence of dominant AF interactions. On lowering the temperature, the wTproduct decreases. Below 20 K, it vanishes to nearly zero for both compounds, indicating that strong antiferromagnetic interactions induce a singlet ground state, S T = 0. To evaluate the intradimer magnetic interaction, the magnetic data were fitted to a simple S= 1/2 spin dimer model with the following Hamiltonian, H¼2J~ S1~ S2  ;and the analytical susceptibility expression of Bleaney and Bowers. 75 An excellent agreement between the experimental data and the model is observed with J/k B = 550(10) K and g=2.1(fixed)forsyn-11d2H 2 O,andJ/k B = 69.5(5) K and g= 2.01(5) for anti-4d. It is worth mentioning that as usually done for systems with a singlet ground state, Curie impurities have been included in this model allowing the estimation of their presence at 3.7 and 3.8% of a S=1/2spin. Singlet and triplet states of syn-[Cu 2 (quin) 2 (3a1pO) 2 ] were calculated by optimizing the X-ray structure without restrictions in bulk acetonitrile. According to 2J=E(S=1)E(S T =0), 72 the sign and the magnitude of the magnetic coupling constant can be estimated as 163.1 K. The calculations predict a singlet ground state also for an anti isomer, although no direct bonding was located between the copper(II)ionsbyAIManalysisineither case (Fig. 12). 58 The calculated value of the magnetic coupling constant for isolated syn-[Cu 2 (quin) 2 (3a1pO) 2 ]differsfromthe experimental one for bulk syn-11d2H 2 O. For the optimized syn- [Cu 2 (quin) 2 (3a1pO) 2 ], yamounts to 97.81and tto 431.Inlinewith the previous discussion, a smaller value of yis, as expected, associated with a larger tand a weaker AF interaction. The magnetic susceptibility of [Cu(quin) 2 ] n (g) was also studied. This compound features an infinite chain structure with a 4.8617(2) Å distance between adjacent copper(II) ions, bridged by two anti(eq)-syn(ax)-carboxylate groups. On lowering the temperature down to 60 K, the wTproduct is quasi-constant with the 0.46 cm 3 K mol 1 value being in good agreement with the presence of a S= 1/2 spin. At lower temperatures, wTslightly increases (up to 0.58 cm 3 K mol 1 at 1.85 K and 0.1 T) suggesting dominant, but very weak, ferromagnetic interactions between spin carriers. A Heisenberg chain model of ferromagnetically coupled S= 1/2 spins with the following spin Hamiltonian, H¼2JP i ~ Si~ Siþ1, was employed to fit the experimental data. Using the analytical expression of susceptibility proposed by Baker et al., 76 the experimental data are remarkably well reproduced down to 1.85 K with J/k B = +0.04(1) K and g= 2.22(5). As expected, the double carboxylate bridges mediate weak ferromagnetic interactions between S= 1/2 Cu(II) spins. 77 3.6. Infrared spectroscopy The presence of quinaldinate and amino alcohol ligands is clearly evident from infrared spectra. Owing to the overlap of some of their characteristic absorption bands and the engagement of NH 2 and OH groups in hydrogen bonds, not all relevant features of the two ligand types can be unambiguously assigned. It may be noted that compounds with the same solidstate structure have very similar infrared spectra. The identification of the quinaldinate absorptions was facilitated by the spectrum of [Cu(quin) 2 ] n (g), a homoleptic complex. Frequencies of the n as (COO  ) and n s (COO  ) vibrational modes, listed in Table S18 (ESI†), are of particular importance as they are Fig. 12 Bond critical points (bcps) and corresponding bond paths of the calculated electron density of the singlet syn-[Cu 2 (quin) 2 (3a1pO) 2 ] in the Cu 2 (m-O) 2 plane. The contour map of the Laplacian of the electron density (r 2 r) is also plotted (above); the electron spin-density plot for the singlet ground state of the same species (below). Solid lines and red tones correspond to positive values whereas dashed lines and blue tones are for negative values. Paper NJC Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 New J. Chem., 2022, 46, 6899–6920 | 6917 sensitive to the carboxylate binding mode. 78 The difference in their positions is known as the Dvalue. Magnitudes of Dfor all our compounds with monodentate carboxylates are in line with the expectations. 78 However, the Dcriterion fails for [Cu(quin) 2 ] n (g) as the frequency difference amounts to 272 cm 1 .Itsmagnitude is larger than expected for a bidentate bridging carboxylate coordination. 78 Inthecaseof[Cu(2a2m1pO) 2 ](2a2m1pOHH) 2 - (quin) 2 (9f), only non-coordinated quinaldinate ions are present. Their role of counter anions is evident from the spectrum: the n as (COO  ) vibration is associated with the band at 1553 cm 1 and that of the n s (COO  ) vibration with the band at 1372 cm 1 .Asa result, the value of Damounts to 181 cm 1 .Theionictypee compounds exhibit carboxylate bands at almost the same positions as 9f. It should be noted that a set of four peaks with medium intensity, i.e., at 1567, 1510, 1463 and 1436 cm 1 for g, invariably appears in the spectra of all quinaldinate complexes at approximately the same frequencies. A close survey of the infrared data of our copper(II) compounds shows that no information about the binding mode of the amino alcohol ligand can be extracted from their spectra. The n(N–H) and n(O–H) vibrations can be told apart only in rare cases. Due to extensive participation of NH 2 and OH groups in hydrogen bonding, N–H and O–H stretches often appear as broad bands. 79 The expected region for the NH 2 deformation band in primary amines, 1650–1590 cm 1 , 79 overlaps with the most intense quinaldinate signature band, the n as (COO  ) band. Therefore, these bands could not be unambiguously assigned. The presence of alcohol in the compound may be seen in another spectral region: the region of C–O stretching absorptions. The n(C–O) absorptions are seen as strong bands with their frequencies sensitive to the nature of the alcohol. 79 The alcohols in the bonded state are reported to absorb very broadly and diffusely near 650 cm 1 owing to the out-of-plane C–OH deformation. 79 Our compounds with amino alcohols also reveal a band of medium intensity in this region (Table S19, ESI†). The spectra of type acomplexes are the least uniform: the number and the frequencies of the bands in the n(N–H)/n(O–H) region differ for all. The n(C–O) spectral region reveals intense bands: 1a with a primary alcohol 2aeOH features a band at 1034 cm 1 ,7a with a secondary alcohol 1a2bOH absorbs at 1137–961 cm 1 and 6a with a tertiary alcohol 1a2m2pOH displays several bands in the 1178–958 cm 1 region. One of the common spectral features for 1a,6a,7a and 11a is four absorptions in the region of n as (COO  ) and N–H bending vibrational mode, as exemplified by 1604, 1587, 1562 and 1550 cm 1 bands for 1a. The high-frequency band at ca. 1604 cm 1 was tentatively assigned to the n as (COO  ) vibration and the rest to the N–H bending vibrations. The trans- [Cu(quin) 2 ] structural fragment leaves its fingerprint in the shape and frequencies of four bands in the out-of-plane C–H region. It is to be noted that the crystallization solvent molecules and a different solid-state structure of 11a3a1pOH make its infrared spectrum markedly different from that of its unsolvated counterpart 11a. The infrared spectra of type bcompounds are very much alike. For the 8b and 11b pair, there are four bands in the n(N–H)/n(O–H) region. Owing to the secondary nature of the amino alcohol in 2b, the number of peaks in this region is smaller. The spectra of all three reveal two prominent absorptions in the n as (COO  )/N–H bending region: for example, the spectrum of 11b reveals an intense band at 1641 cm 1 and a band at 1594 cm 1 . The same absorption pattern may be observed for the spectra of 8c and 11c. Again, their similarity can be traced to the similarity of their solid-state structures. The spectra of the dinuclear complexes should be free of n(O–H) absorptions in keeping with the formulation as an amino alcoholate rather than an alcohol complex. This expectation is realized for compounds that do not contain solvent molecules of crystallization, i.e., methanol, 3-amino-1-propanol or water. The spectrum of anti-[Cu 2 (quin) 2 (2eaeO) 2 ](anti-4d) differs from the spectra of the 3a1pO  anti dimers, anti- 11d4MeOH,anti-11d2MeCN and anti-11d2MeOH2(3a1pOH). In the spectrum of anti-4d,then(N–H) absorption occurs as a single sharp band at 3183 cm 1 . Broad bands, belonging to solvent molecules of 3-amino-1-propanol and/or methanol for anti-11d2MeOH2(3a1pOH) and anti-11d4MeOH,mask the n(N–H) bands of the coordinated amino alcoholate. The presence of solvent molecules is apparent also from the characteristic region of the C–O stretching vibrations: for anti-11d4MeOH, a very intense band may be observed at 1022 cm 1 , whereas for anti-11d2MeOH2(3a1pOH) aband occurs at 1051 cm 1 . Their intensities diminish with time, in line with the rapid loss of solvent molecules. The presence of the acetonitrile solvent molecules in anti-11d2MeCN is ascertained by the sharp band at 2249 cm 1 . 79 The spectra of syn-8d,syn-9d and syn-10d areverymuchalike.Itistobe noted that unambiguous identification by means of X-ray crystallography was accomplished only for syn-8d.Basedon the similarity of their spectra, it can be claimed with a high probability that their solid-state structures are very similar. All three reveal two sharp bands that can be attributed to n(N–H) absorptions. For syn-8d, the peaks occur at 3251 and 3145 cm 1 .syn-11d2H 2 Oalso features two bands at almost thesamefrequencies.Thewatersolvatehasanadditional broad band at 3469 cm 1 whoseoriginliesinthen(O–H) vibrations of solvent water molecules. The spectral features of type eionic compounds with chelating amino alcohol ligands are very similar. They display two bands in the n(N–H)/n(O–H) region, at 3236 and 3122 cm 1 (5e). Surprisingly, in spite of the same binding mode employed by the amino alcohol ligands, the spectra are markedly different from the spectra of type bcomplexes. The spectrum of [Cu(2a2m1pO) 2 ](2a2m1pOHH) 2 (quin) 2 (9f), a compound which contains both the amino alcoholate ligand and the cationic form of the parent amino alcohol, reveals the n(N–H) vibration of the NH 2 group as a sharp absorption of medium intensity at 3315 cm 1 . A broad absorption that spans the 3200–2500 cm 1 region is attributed to the n(N–H) and n(O–H) absorptions of the hydrogen bonded NH 3+ and OH entities. The region of the N–H bending vibrations reveals three bands, at 1644, 1602 and 1582 cm 1 . The n(C–O) vibrations may be seen as strong bands at 1055 and 1010 cm 1 . NJC Paper Open Access Article. Published on 01 March 2022. Downloaded on 9/26/2022 8:54:09 AM. This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. View Article Online 6918 | New J. Chem., 2022, 46, 6899–6920 This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2022 4. Conclusions The Cu(II)–quinaldinate–amino alcohol reaction systems display great structural diversity in their products which may be classified into seven distinctly different structural types. The series encompasses mononuclear, dinuclear and 1D-polymeric species with either intact amino alcohols or amino alcoholate ions serving as ligands. No correlation between the nature of the product and the applied reaction conditions could be discerned. To the best of our knowledge, copper(II) complexes with three out of eleven amino alcohols, 2-methylamino- ethanol, 1-amino-2-methyl-2-propanol and 1-amino-2-butanol, have not been prepared prior to this study. The richest system in terms of products was that of 3-amino-1-propanol: it has yielded nine compounds. Two mononuclear 3-amino-1- propanol complexes, trans-[Cu(quin) 2 (3a1pOH) 2 ] and [Cu(quin) 2 - (3a1pOH)] with a chelating amino alcohol, were subjected to DFT calculations which show their facile interconversion in the solution to proceed via an intermediate five-coordinate species. The dinuclear amino alcoholate complex, [Cu 2 (quin) 2 (3a1pO) 2 ], displayed syn-andanti-isomerism. DFT calculations on the isolated isomers revealed the syn isomer as the most stable one with its stability originating from an intramolecular ppstacking interaction between quinaldinates. Furthermore, calculations show that both isomers display antiferromagnetic interactions between S=1/2Cu( II) spins. These results qualitatively agree with the experimental value for syn-[Cu 2 (quin) 2 (3a1pO) 2 ]2H 2 O. In line with previous studies, the nature and strength of the magnetic exchange depends upon the geometry of the Cu(m-O) 2 Cu core. The mononuclear complexes trans-[Cu(quin) 2 L 2 ] (where L denotes amino alcohol) and [Cu(quin) 2 L] with a bidentate chelating amino alcohol display very weak to weak antiferromagnetic coupling through supramolecular contacts in their solid-state structures. By analogy, [Cu(2a2m1pO) 2 ](2a2m1pOHH) 2 (quin) 2 with an efficient separation of the S=1/2Cu( II) spins by the counter ions does not display significant magnetic interactions. [Cu(quin) 2 ] n , the homoleptic quinaldinate complex with an infinite chain structure, is the only one in the series that features weak but nevertheless observable, ferromagnetic behavior. Author contributions Conceptualization: B. M. and N. P.; investigation and formal analysis: all authors; writing – review & editing: B. M., N. P., R. C. and J. L. S. Funding Research was funded by the Slovenian Research Agency (Junior Researcher Grant for N. 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