Synthesis of chiral iron-based ionic liquids: modelling stable hybrid materials

1 FINAL VERSION ACCEPTED Syn hesis o Chi al I on-Based Ionic Liquids: Modelling S able Hyb id Ma e ials† Ca men Ma in,a,b,* Is ael Cano,c,* Fabio Scé,a Rubén Pé ez-Agui e,d Ca olina Gimbe -Su iñach,e Pila Lopez-Co nejob and Imanol de Ped oa ABSTRACT: Fi e chi al i on-con aining ionic liquids we e syn he ized om se e al chi al ionic liquids (CILs) based on di e en imidazolium ca ions. These no el compounds we e p epa ed h ough an easy syn he ic me hod consis ing in mixing 1 equi alen o i on sal FeX3 (X = Cl o B ) and 1 equi alen o chi al ionic liquid. The so-ob ained chi al i on- based ionic liquids con ain easily unable imidazolium ca ions, which allow he p epa a ion o a wide ange o compounds wi hin di e en unc ional g oups and chi al moie ies. These chi al i on-based ionic liquids ha e been ully cha ac e ized by a wide a ie y o echniques, including pola ime y, induc i ely coupled plasma op ical emission spec ome y, elemen al analysis, he mog a ime ic analysis, di e en ial scanning calo ime y, magne ic suscep ibili y measu emen s, and UV- is, a enua ed o al e lec ion Fou ie - ans o m in a ed and Raman spec oscopies. Such expe imen s con i med he s uc u e o hese newly ma e ials, as well as hei appealing p ope ies. The combina ion o a chi al moie y wi h a halo e a e anion wi hin he ILs s uc u e allows he o ma ion o e y s able and mul i unc ional compounds wi h p omising chi al, magne ic, op ical and acidic p ope ies. The esul ing chi al i on-based ILs exhibi g ea po en ial o use in a ange o applica ions such as enan ioselec i e ca alysis o chi al ecogni ion, o name a ew. Keywo ds: Acidic chi al pa amagne ic ionic liquid • hyb id ma e ial • imidazolium-based halome alla e complex • i on-con aining ionic liquid a Uni e sidad de Can ab ia, CITIMAC, Facul ad de Ciencias, A da. de los Cas os s/n, 39005 San ande , Spain. b Uni e sidad de Se illa, Depa men o Physical Chemis y, Facul y o Chemis y, c/P o eso Ga cía González s/n, 41012 Se illa, Spain. c School o Chemis y, Uni e si y o No ingham, NG7 2RD, No ingham, UK. d Uni e sidad del País Vasco, Depa amen o de Química Ino gánica, Facul ad de Ciencia y Tecnología, Apa ado 644, E-48080, Bilbao, Spain. e Ins i u e o Chemical Resea ch o Ca alonia (ICIQ). A inguda Països Ca alans 16, 43007 Ta agona, Spain. † Elec onic supplemen a y in o ma ion (ESI) a ailable: C ys allog aphic da a, analy ical and spec al da a. CCDC: 1961691 and 1962239. 2 INTRODUCTION Mul i unc ional compounds based on ionic liquids (ILs) ha e gained conside able in e es owing o he unique p ope ies o ILs (e.g., good he mal s abili y, high ionic conduc i i y and wide elec ochemical s abili y window).1,2,3,4 In pa icula , acidic ionic liquids (AILs) ha e been ex ensi ely in es iga ed due o hei capabili y o ac as memb anes, elec oly es o ba e ies and capaci o s o ca alys s (e.g., depolyme isa ion o cellulose, p oduc ion o biodiesel, oxida ion eac ions, e c.).5,6 Among hem, halome alla e-based ILs7 a e an impo an subg oup o AILs which con ain a me al-based Lewis acid wi hin hei s uc u e. This me al componen enhances hei ea u es agains pu ely o ganic ILs, such as lowe iscosi ies and highe conduc i i ies, and makes hem e y in e es ing compounds o a numbe o applica ions, including elec ical-ene gy s o age8 and ca alysis (e.g. F iedel–C a s eac ions, Michael addi ion and polye hylene e eph hala e (PET) glycolysis).9,10,11,12 In e es ingly, hei a chi ec u e can be easily modula ed o c ea e ailo -made ILs wi h di e en physical and chemical p ope ies. In his ega d, chi al cen e s o magne ic moie ies wi hin ILs s uc u es can imp o e he AILs pe o mance (e.g. in ca alysis) and une hei p ope ies. Howe e , he de elopmen o new ma e ials wi h simul aneous chi al, magne ic and acidic cha ac e is ic is s ill in i s in ancy and only wo a icles ha e been epo ed on he p epa a ion o acidic chi al pa amagne ic ionic liquids (ACMILs).13,14 Among hem, i is wo h men ioning he wo k o Wa ne and co-wo ke s, in which he syn hesis o chlo o e a e(III) chi al ILs inco po a ing amino acid de i ed ca ions and hei use as chi al ecogni ion agen s o luo escen analy es is desc ibed.13 Recen ly, ou g oup has de eloped new halome alla e ILs based on i on.15,16,17 We ha e shown ha hese so-called halome alla e-based ILs (con aining a Lewis acid and a nucleophile wi hin he s uc u e) display a good ca aly ic ac i i y in he glycolysis o PET, leading o be e yields and selec i i ies han hose epo ed wi h pu ely o ganic ILs.16,17 In a nex s ep, we ha e decided o ex end his wo k in oducing chi al ea u es in o he AILs s uc u es. In his con ex , he imidazolium ca ion is easily unable and allows he in oduc ion o unc ional g oups and chi al moie ies, opening he doo o an eno mous a ie y o compounds. Thus, he ein we epo he syn hesis o i e new and s able chi al imidazolium-based halo e a e(III) ILs wi h di e se a chi ec u es (Fig. 1). To in es iga e hei s abili y and appealing chi al/magne ic p ope ies, a de ailed cha ac e iza ion o hese mul i unc ional ILs was pe o med by he s a e-o - he-a echniques, such as pola ime y, induc i ely coupled plasma op ical emission spec ome y (ICP-OES), elemen al analysis (EA), he mog a ime ic analysis (TGA), di e en ial scanning calo ime y (DSC), UV- is spec oscopy, magne ic suscep ibili y measu emen s, and 3 a enua ed o al e lec ion Fou ie - ans o m in a ed (ATR FT-IR) and Raman spec oscopies. These swi chable ACMILs may be p omising candida es as enan ioselec i e ca alys s (e.g. CO2 ixa ion in o cyclic ca bona es)18 o chi al ecogni ion agen s.13 Fig. 1 O e all scheme o he p epa a ion o ACMLs, p ope ies and applica ions. The e o e, he main objec i e o his wo k is he p epa a ion o a se ies o new mul i unc ional ILs by he p ecise design o he imidazolium ca ion s uc u e and he app op ia e selec ion o he anion. EXPERIMENTAL Gene al P ocedu es Sol en s we e pu chased om Sigma-Ald ich as HPLC g ade and d ied by means o an Ine Pu esol MD pu i ica ion sys em. All eagen s we e pu chased om comme cial supplie s (Sigma Ald ich and Ac oss) and pu i ied when equi ed by li e a u e p ocedu es.19 The ion exchange esin Ambe li e IRA-402(OH) was supplied by Al a Aesa . Elemen al analysis (EA). Elemen al analyses we e pe o med by he Elemen al Analysis Se ice o he Uni e si y o No ingham. Nuclea magne ic esonance (NMR). 1H and 13C NMR spec a we e eco ded on a B uke AV3400 400 MHz and a B uke DPX500 500 MHz nuclea magne ic esonance spec ome e s, and e e enced o he esidual NMR sol en signals. Signals a e quo ed as s (single ), d (double ), ( iple ), dd (double double ), d ( iple double ) and m (mul iple ). 4 Elec osp ay ioniza ion mass spec ome y (ESI-MS). ESI-MS analyses we e ca ied ou on a B uke ESI-TOF Mic oTOF II and O bi ap Eli e (The mo Scien i ic) spec ome e s. Fou ie ans o m in a ed spec oscopy (FT-IR). FT-IR measu emen s we e pe o med on a B uke Alpha Se ies FT-IR spec ome e equipped wi h an a enua ed o al e lec ance (ATR) module. The ATR FT-IR spec a we e eco ded by collec ing 24 scans o a compound in he ATR module. Non-pola ized Raman spec a. The non-pola ized Raman spec a we e eco ded in he backsca e ing geome y wi h a Ho iba T64000 iple spec ome e wi h a con ocal mic oscope in he sub ac i e mode which had a esolu ion o 0.6 cm-1, a 1800 g oo es/mm g a ing and a 100-μm sli was equipped wi h a liquid N2-cooled CCD de ec o (Jobin-Y on Symphony). A 647 nm line o a Cohe en Inno a Spec um 70C A +-K + lase was ocused down wi h a 20x objec i e and kep he powe on he sample below 5 mW o a oid lase -hea ing e ec s on he ma e ial being es ed and he concomi an so ening o he obse ed Raman peaks. UV- is spec oscopy. UV− is measu emen s we e ca ied ou on a Shimadzu UV- 2401PC spec opho ome e equipped wi h a pho omul iplie de ec o , double beam op ics, and D2 and W ligh sou ces. Samples we e measu ed a 25°C and wi h dime hyl o mamide (DMF) as sol en . Di e en ial scanning calo ime y (DSC). DSC measu emen s we e ca ied ou on a TA ins umen s Disco e y om -90 °C o 150 °C a a a e o 10 °C/min unde ni ogen a mosphe e. The mog a ime ic analysis (TGA). The mog a ime ic measu emen s we e ca ied ou on a TA ins umen s Disco e y a a hea ing a e o 10 °C/min and in a empe a u e ange om 100 °C o 1000 °C unde N2 in a pla inum c ucible. No e ha he decomposi ion empe a u e (Td) was de e mined by TGA a 10% weigh loss o he analy e. Induc i ely coupled plasma op ical emission spec ome y (ICP-OES). The i on con en de e mina ion was pe o med h ough analysis o he samples by ICP-OES on a Pe kin Elme Op ima 2000 DV ICP-OES. The samples we e p epa ed by dilu ing 25 mL o ionic liquid wi h app oxima ed i on concen a ion o 150 mg/L (ppm) in HNO3 wi h a concen a ion o 2% ( /V). Calib a ion cu es we e p epa ed using s anda d solu ions o concen a ions be ween 0–250 ppm p epa ed by dilu ion o he s anda d solu ion. The i on S anda d o ICP T aceCERT® (10′000 mg/L Fe in ni ic acid) was supplied by Sigma Ald ich. Magne iza ion measu emen s. DC magne ic suscep ibili y measu emen s o ionic liquids 5-9 we e ca ied ou in a Quan um Design MPMS SQUID magne ome e using a 5 ield o 1 kOe in he 2-300 K empe a u e ange. Magne iza ion as a unc ion o ield (H) was measu ed using he same magne ome e in he -50 ≤ H/kOe ≤ 50 a 2 K a e cooling he sample in ze o ield. Pola ime y. Op ical o a ions we e measu ed in a 1.0 dm ube wi h a Pe kin Elme spec opola ime e (model 341) equipped wi h a Na lamp. X- ay c ys al s uc u e de e mina ions (CCDC: 1961691 o 1 and 1962239 o 4). X- ay c ys al s uc u e de e mina ions we e pe o med a he X- ay Se ice o he Uni e si y o No ingham. C ys als sui able o X- ay di ac ion we e selec ed and co e ed wi h “ omblin” (YR-1800 pe luo opolye he oil). The c ys al was hen moun ed on a polyme - ipped Mic oMoun TM and cooled o 120 K. Single c ys al X- ay di ac ion da a we e collec ed using an Agilen Supe No a di ac ome e , A las CCD a ea de ec o (mi o - monoch oma ed Cu-Kα adia ion sou ce; λ = 1.54184 Å o g aphi e-monoch oma ed Mo- Kα adia ion sou ce; λ = 0.7103 Å; ω scans) and an Agilen Supe No aII di ac ome e Ti an S2 CCD a ea de ec o (mi o monoch oma ed Cu-Kα adia ion sou ce; λ = 1.54184 Å; ω scans). C ys al s uc u es we e sol ed and e ined by means o he Olex2 so wa e package,20,21 p og am using Cha ge Flipping and e ined wi h he ShelXL.22 C ys allog aphic da a ha e been deposi ed in he Camb idge C ys allog aphic Da a Cen e unde e e ence numbe s CCDC 1961691 and 1962239 o CILs 1 and 4, espec i ely. These da a can be ob ained ee o cha ge ia www.ccdc.cam.ac.uk/da a_ eques /ci . Gas Ch oma og aphy (GC). Analyses (de e mina ion o enan iome ic excess) o he eac ion mix u es we e pe o med on a The mo Scien i ic T ace 1310 Gas Ch oma og aph wi h a Lipodex A (hexakis-(2,3,6- i-O-pen yl)-α-cyclodex in) 25m column. Syn he ic P ocedu es Syn hesis o chi al imidazolium-based ionic liquids. - (S)-1-(2-Me hylbu yl)-2,3-dime hylimidazolium chlo ide ([S-me hylBMMIm]Cl, 1). (S)- (+)-1-Chlo o-2-me hylbu ane (12.0 g, 0.11 mol, 1.10 equi alen s) and 1,2-dime hyl-1H- imidazole (9.81 g, 0.10 mol, 1.00 equi alen ) we e dissol ed in 5.50 mL o CH3CN in a ound bo om lask unde ine a mosphe e. The eac ion mix u e was hea ed o 5 days a 100 °C unde e lux. A e wa ds, he solu ion was cooled o oom empe a u e (R.T.) and he ola ile ma e ials we e e apo a ed unde acuum. The emaining o ange oil was e-dissol ed in he minimum amoun o d y CH3CN and added d opwise ia cannula o a well-s i ed solu ion o e hyl ace a e (CH3CN:e hyl ace a e a io ca. 1:5). Once he addi ion o he CH3CN solu ion was comple ed, he mix u e was cooled a -30 °C in he eeze o c ys allize. The inal p oduc was washed wi h e hyl ace a e and d ied unde 6 acuum, ob aining a pale yellow powde . Yield: 12.1 g (0.06 mol, 65 %). C ys als o 1 sui able o X- ay di ac ion analysis we e ob ained a R.T. by slow di usion o e hyl ace a e apou in o an CH3CN solu ion o 1. 1H NMR (400 MHz, CDCl3): δ = 7.88 (d, 3JHH = 2.0 Hz, 1H, CHA ), 7.44 (d, 3JHH = 2.0 Hz, 1H, CHA ), 4.08 (dd, 2JHH = 15.0 Hz and 3JHH = 7.5 Hz, 1H, NCH2), 4.08 (s, 3H, NCH3), 3.94 (dd, 2JHH = 14.0 Hz and 3JHH = 9.0 Hz, 1H, NCH2), 2.77 (s, 3H, NCCH3), 1.90-1.77 (m, 1H,CHCH3), 1.44-1.32 (m, 1H, CH2CH3), 1.26-1.14 (m, 1H, CH2CH3), 0.90 ( , 3JHH = 7.0 Hz, 3H, CH2CH3), 0.89 (d, 3JHH = 6.0 Hz, 3H, CHCH3). 13C NMR (101 MHz, CDCl3): δ = 143.8 (1C, NCN), 123.4 (1C, CHA ), 121.7 (1C, CHA ), 54.6 (1C, NCH2), 36.1 (1C, NCH3), 35.7 (1C, NCCH3), 26.6 (1C, CHCH3), 16.62 (1C, CH2CH3), 11.1 (1C, CHCH3), 10.8 (1C, CH2CH3). ESI-MS (+ e): m/z = 167.1553 [M-Cl]+ (calcula ed: m/z = 167.1548). Cha ac e is ic IR bands (cm-1): 3121- 3022 (C-H sp2), 2960-2849 (C-H sp3), 1587 (C=C/C=N), 1536 (C-C/C-N), 1120(C-N), 910 (C-H sp2), 820 (C-H sp2), 758 (C-H sp2). [α]  = -2.4 (c = 5 mg/1 mL MeOH). Td = 250 ºC. (Fig. S1, S2, S7, S18, S26 and S51 in Suppo ing In o ma ion). - (R)-3-(2,3-Dihyd oxyp opyl)-1-me hylimidazolium chlo ide ([R-diOHP MIm]Cl, 2) and (S)-3-(2,3-dihyd oxyp opyl)-1-me hylimidazolium chlo ide ([S-diOHP MIm]Cl, 3). 2 and 3 we e p epa ed acco ding o p ocedu es desc ibed in he li e a u e.23 he (R) o (S)-3- Chlo o-1,2-p opanediol (12.2 g, 0.11 mol, 1.10 equi alen s) was placed in a ound bo om lask wi h a s i ing ba and dissol ed in CH3CN (10.0 mL) unde ine a mosphe e. A e addi ion o 1-me hyl-1H-imidazole (9.55 g, 0.10 mol, 1.0 equi alen ), he eac ion mix u e was hea ed a 90 °C o 48 h unde e lux. Upon comple ion o he eac ion, he sol en was emo ed in acuo. Then, he eac ion c ude was e-dissol ed in he minimum amoun o d y CH3CN and added d opwise ia cannula o a well-s i ed solu ion o e hyl ace a e (CH3CN:e hyl ace a e a io ca. 1:5). Finally, he mix u e was cooled a -30 °C in he eeze o c ys allize. The inal p oduc was washed wi h e hyl ace a e and d ied unde acuum, ob aining a pale o ange powde . Yield: 15.4 g (0.08 mol, 80 %). 1H NMR (400 MHz, D2O): δ = 8.77 (s, 1H, N-CH-N), 7.52 (m, 1H, CHA ), 7.48 (m, 1H, CHA ), 4.40 (dd, 2JHH = 15.0 Hz and 3JHH = 3.0 Hz, 1H, NCH2), 4.22 (dd, 2JHH = 14.5 Hz and 3JHH = 3.5 Hz, 1H, NCH2), 4.11-4.04 (m, 1H, CHOH), 3.93 (s, 3H, NCH3), 3.63 (dd, 3JHH = 5.0 Hz and 3JHH = 1.5 Hz, 2H, CH2OH). 13C NMR (101 MHz, D2O): δ = 136.6 (1C, NCHN), 123.5 (1C, CHA ), 122.9 (1C, CHA ), 69.8 (1C, CHOH), 62.4 (1C, CH2OH), 51.7 (1C, NCH2), 35.7 (1C, NCH3). ESI-MS (+ e): m/z = 157.0979 [M-Cl]+ (calcula ed: m/z = 157.0977). Cha ac e is ic IR bands (cm-1): 3325 (O-H), 3210 (O-H), 3165-3058 (C-H sp2), 2933-2830 (C-H sp3), 1632 (C=C/C=N), 1558 (C-C/C-N), 1164 (C- N), 1109 (C-O), 1059 (C-O), 941 (C-H sp2), 846 (C-H sp2), 773 (C-H sp2). (Fig. S3, S4, S8 and S19). 7 R-[diOHP MIm]Cl, 2: [α]  = +15.6 (c = 5 mg/1 mL MeOH). Td (10%) = 300 ºC. (Fig. S27). S-[diOHP MIm]Cl, 3: [α]  = -16.0 (c = 5 mg/1 mL MeOH). Td (10%) = 280 ºC. (Fig. S28). - 1-((1S,2R,4S)-(+)-Men hoxyme hyl)-2,3-dime hylimidazolium chlo ide ([R-men hyl MMIm]Cl, 4). 4 was p epa ed acco ding o p ocedu es desc ibed in he li e a u e.24 (1S,2R,4S)-(+)-Chlo ome hyl men hyl e he (5.00 g, 24.4 mmol, 1.05 equi alen s) and 1,2-dime hyl-1H-imidazole (1.00 g, 23.2 mmol, 1.00 equi alen s) we e dissol ed in CH3CN (75 mL) in a ound bo om lask unde ine a mosphe e. The eac ion mix u e was hea ed o 24 h a 90 °C unde e lux. Nex , he solu ion was cooled o R.T. and he sol en was e apo a ed unde acuum. Finally, he p oduc was washed h ee imes wi h die hyl e he and d ied unde acuum o gi e a whi e powde . Yield = 6.27 g (20.9 mmol, 90 %). C ys als o 4 sui able o X- ay di ac ion analysis we e ob ained a 6 ºC in CH3CN. 1H NMR (400 MHz, CDCl3): δ = 7.88 (d, 3JHH = 2.0 Hz, 1H, CHA ), 7.77 (d, 3JHH = 2.0 Hz, 1H, CHA ), 5.71 (d, 2JHH = 11.0 Hz, 1H, NCH2O), 5.64 (d, 2JHH = 11.0 Hz, 1H, NCH2O), 4.02 (s, 3H, NCH3), 3.30 ( d, 3JHH = 10.0 Hz and 3JHH = 4.0 Hz, 1H, OCH), 2.83 (s, 3H, NCCH3), 2.09-2.03 (m, 1H, CH2), 1.97-1.87 (m, 1H, CH2), 1.97-1.87 (m, 1H, CHCH(CH3), 1.69-1.58 (m, 2H, CH2), 1.45-1.32 (m, 1H,CHCH3), 1.26-1.18 (m, 1H, CHCH(CH3)2), 0.95-0.88 (m, 2H, CH2), 0.92 (d, 3JHH = 6.6 Hz, 3H, CHCH3), 0.88 (d, 3JHH = 7.5 Hz, 3H, CHCH(CH3)2), 0.51 (d, 3JHH = 7.0 Hz, 3H, CHCH(CH3)2). 13C NMR (101 MHz, CDCl3): δ = 145.1 (1C, NCN), 123.0 (1C, CHA ), 121.8 (1C, CA ), 79.6 (1C, OCH), 76.4 (1C, NCH2O), 47.9 (1C, CH2), 40.4 (1C, CH2),35.9 (1C, NCH3), 34.2 (1C, CHCH(CH3)2), 31.4 (1C, CHCH3), 25.6 (1C, CHCH(CH3)2), 22.9 (1C,CH2), 22.3 (1C, CHCH3), 21.0 (1C, CHCH(CH3)2), 15.7 (1C, CHCH(CH3)2), 10.8 (1C, NCCH3). ESI-MS (+ e): m/z = 265.2276 [M-Cl]+ (calcula ed: m/z = 265.2280). Cha ac e is ic IR bands (cm- 1): 3159-3072 (C-H sp2), 2960-2855 (C-H sp3), 1634 (C=C/C=N), 1571 (C-C/C-N), 1166 (C-O-C), 1042 (C-O-C), 838 (C-H sp2), 747 (C-H sp2). [α]  = +112.0 (c = 5 mg/1 mL MeOH). Td = 212 ºC. (Fig. S5, S6, S9, S20, S29 and S52). 1H and 13C NMR, ESI-MS, FT-IR and [α]  da a we e consis en wi h hose p e iously epo ed.24 Syn hesis o i on-con aining ionic liquids. 1.0 equi alen o FeCl3 was mixed wi h 1.0 equi alen o he co esponding imidazolium sal (1–4) in a Schlenk lask unde A a mosphe e (glo ebox). A e s i ing o 12 h a 90 ºC, he acidic chi al pa amagne ic ionic liquids 5–7 and 9 we e ob ained wi h quan i a i e con e sion. Simila ly, he acidic chi al pa amagne ic ionic liquid 8 was p epa ed by mixing 1.0 equi alen o FeB 3 wi h 1.0 equi alen o (S)-3-(2,3-dihyd oxyp opyl)-1-me hylimidazolium b omide (S- [diOHP MIm]B ). The eac ion was s i ed unde A a mosphe e o 12 h a 90 ºC o ob ain 8. 8 S-[diOHP MIm]B syn hesis: A solu ion con aining 950.0 mg o 3 (4.9 mmol) in 5 mL o H2O was passed h ough a column packed wi h anion-exchange Ambe li e esin IRA- 402(OH) using H2O as eluen . A e wa ds,4.9 mmol o HB (aq.) 48 w % was added o he aqueous solu ion o he hyd oxide o m o 3 collec ed. A e addi ion o HB , he eac ion mix u e was s i ed o e nigh a R.T. Upon comple ion o he eac ion he sol en was emo ed in acuo ( o a y e apo a o ), yielding S-[diOHP MIm]B . - (S)-1-(2-Me hylbu yl)-2,3-dime hylimidazolium e achlo o e a e(III) ([S-me hylBMMIm] [FeCl4], 5). ESI-MS (+ e): m/z = 167.15 [M-FeCl4]+ (calcula ed: m/z = 167.1548). ESI- MS (- e): m/z = 197.81 [FeCl4]- (calcula ed: m/z = 197.8074). Elemen al Analysis: Obs. C, 32.07; H, 5.11; N, 7.82. Calc. C, 32.91; H, 5.25; N, 7.68. ICP-OES (% weigh ): Obs. Fe, 14.81. Calc. Fe, 15.30. Cha ac e is ic IR bands (cm-1): 3178-3086 (C-H sp2), 2966- 2854 (C-H sp3), 1586 (C=C/C=N), 1536 (C-C/C-N), 1165 (C-N), 837 (C-H sp2), 804 (C- H sp2), 739 (C-H sp2). Raman (cm-1): 334, 332, 141, 110 (Fe-Cl). [α]  = -2.6 (c = 5 mg/1 mL MeOH). Td (10%) = 334 ºC and Tg = -63 ºC. UV-Vis [λmax/nm (ε/M−1·cm−1)]: 315 (20000), 364 (18666). μe = 5.88 μB/molecule. (Fig. S10, S11, S21, S30, S31, S40 and S45). - (R)-3-(2,3-Dihyd oxyp opyl)-1-me hylimidazolium e achlo o e a e(III) ([R-diOHP MIm][FeCl4], 6). ESI-MS (+ e): m/z = 157.0970 [M-FeCl4]+ (calcula ed: m/z = 157.0972). ESI-MS (- e): m/z = 197.8073 [FeCl4]- (calcula ed: m/z = 197.8074). Elemen al Analysis: Obs. C, 22.35; H, 3.72; N, 7.04. Calc. C, 23.69; H, 3.69; N, 7.89. ICP-OES (% weigh ): Obs. Fe, 14.75. Calc. Fe, 15.74. Cha ac e is ic IR bands (cm-1): 3513 (O-H), 3364 (O- H), 3149-3096 (C-H sp2), 2962-2881 (C-H sp3), 1690 (C=C/C=N), 1556 (C-C/C-N), 1164 (C-N), 1096 (C-O), 1037 (C-O), 926 (C-H sp2), 829 (C-H sp2), 740 (C-H sp2). Raman (cm-1): 330, 328, 138, 108 (Fe-Cl). [α]  = +12.2 (c = 5 mg/1 mL MeOH). Td (10%) = 259 ºC and Tg = -35 ºC. UV-Vis [λmax/nm (ε/M−1·cm−1)]: 316 (84000), 364 (85000). μe = 5.89 μB/molecule. (Fig. S12, S13, S22, S32, S33, S41 and S46). - (S)-3-(2,3-Dihyd oxyp opyl)-1-me hylimidazolium e achlo o e a e(III) ([S-diOHP MIm][FeCl4], 7). ESI-MS (+ e): m/z =157.0970 [M-FeCl4]+ (calcula ed: m/z = 157.0972). ESI-MS (- e): m/z = 197.8073 [FeCl4]- (calcula ed: m/z = 197.8074). Elemen al Analysis: Obs. C, 22.54; H, 3.70; N, 7.02. Calc. C, 23.69; H, 3.69; N, 7.89. ICP-OES (% weigh ): Obs. Fe, 15.24. Calc. Fe, 15.74. Cha ac e is ic IR bands (cm-1): 3513 (O-H), 3364 (O- H), 3149-3096 (C-H sp2), 2962-2881 (C-H sp3), 1690 (C=C/C=N), 1556 (C-C/C-N), 1164 (C-N), 1096 (C-O), 1037 (C-O), 926 (C-H sp2), 829 (C-H sp2), 740 (C-H sp2). Raman (cm-1): 332, 330, 140, 111 (Fe-Cl). [α]  = -13.6 (c = 5 mg/1 mL MeOH). Td (10%) = 257 ºC and Tg = -34 ºC. UV-Vis [λmax/nm (ε/M−1·cm−1)]: 317 (12750), 363 (10500). μe = 5.88 μB/molecule. (Fig. S23, S34, S35, S42 and S47). 9 - (S)-3-(2,3-Dihyd oxyp opyl)-1-me hylimidazolium e ab omo e a e(III) ([S-diOHP MIm][FeB 4], 8). ESI-MS (+ e): m/z = 157.0970 [M-FeB 4]+ (calcula ed: m/z = 157.0972). ESI-MS (- e): m/z = 375.6045 [FeB 4]- (calcula ed: m/z = 375.6042). Elemen al Analysis: Obs. C, 14.76; H, 2.19; N, 5.03. Calc. C, 15.74; H, 2.46; N, 5.26. ICP-OES (% weigh ): Obs. Fe, 10.83. Calc. Fe, 10.48. Cha ac e is ic IR bands (cm-1): 3529 (O-H), 3370 (O- H), 3155-3099 (C-H sp2), 2961-2875 (C-H sp3), 1690 (C=C/C=N), 1563 (C-C/C-N), 1168 (C-N), 1099 (C-O), 1039 (C-O), 925 (C-H sp2), 825 (C-H sp2), 741 (C-H sp2). Raman (cm-1): 295, 198 (Fe-B ). [α]  = -18.4 (c = 5 mg/1 mL MeOH). Td (10%) = 275 ºC and Tg = -31 ºC. UV-Vis [λmax/nm (ε/M−1·cm−1)]: 394(3333), 426 (2619), 473, (3048). μe = 6.09 μB/molecule. (Fig. S14, S15, S24, S36, S37, S43 and S48). - (R)-1-((1S,2R,4S)-(+)-Men hoxyme hyl)-2,3-dime hylimidazolium e achlo o e a e(III) ([R-men hylMMIm][FeCl4], 9). ESI-MS (+ e): m/z = 265.2280 [M-FeCl4]+ (calcula ed: m/z = 265.2280). ESI-MS (- e): m/z = 197.8073 [FeCl4]- (calcula ed: m/z = 197.8074). Elemen al Analysis: Obs. C, 44.32; H, 6.99; N, 7.09. Calc. C, 41.50; H, 6.31; N, 6.05. ICP-OES (% weigh ): Obs. Fe, 11.54. Calc. Fe, 12.06. Cha ac e is ic IR bands (cm-1): 3154-3140 (C-H sp2), 2958-2841 (C-H sp3), 1684 (C=C/C=N), 1582 (C-C/C-N), 1168(C- O), 1091 (C-O), 838 (C-H sp2), 735 (C-H sp2). Raman (cm-1): 335, 332, 142, 112 (Fe-Cl). [α]  = +52.2 (c = 5 mg/1 mL MeOH). Td (10%) = 210 ºC and Tg = 8 ºC. UV-Vis [λmax/nm (ε/M−1·cm−1)]: 318 (20167), 364 (16333). μe = 6.08 μB/molecule. (Fig. S16, S17, S25, S38, S39, S44 and S49). Ca aly ic expe imen s 1.665 mmol o epoxide was mixed wi h 0.083 mmol o he Fe-based ionic liquid in a glass ial wi h a magne ic s i e . Then, he ial was placed in a small eac o wi h a olume o 2 mL and he eac o was lushed wi h ca bon dioxide (CO2) h ee imes be o e he p essu e was kep cons an (2 ba ). A e 24 h o eac ion a he desi ed empe a u e, he eac o was slowly dep essu ized. The p oduc was pu i ied by ex ac ion wi h die hyl e he (2×5 mL) and il a ion wi h SiO2 by lash ch oma og aphy. A e wa ds, he sol en was e apo a ed. The esidue analyzed by 1H NMR o de e mine con e sion and selec i i y and by GC o de e mine he %ee. RESULTS AND DISCUSSION The Fe-con aining CILs 5–9 we e p epa ed in a wo-s ep syn he ic s a egy (Scheme 1, o u he de ails see sec ions Syn hesis o chi al imidazolium-based ionic liquids and Syn hesis o i on-con aining ionic liquids). Fi s , he imidazolium-based CILs 1–4 we e p epa ed acco ding o p ocedu es desc ibed in he li e a u e.23,24 Then, 1 equi alen o FeX3 (X = Cl o B ) was mixed wi h 1 equi alen o he co esponding imidazolium-based 16 Finally, we pe o med he kine ic esolu ion o a acemic mix u e o s y ene oxide h ough he asymme ic cycloaddi ion o CO2 o epoxides ca alyzed by Fe-con aining chi al ionic liquids 5 and 9 (Table 5). Al hough he enan iome ic excesses obse ed a e e y low, his p elimina y expe imen se es as a p oo o concep o he po en ial applica ion o ACMILs as enan ioselec i e ca alys s. Table 5. Kine ic esolu ion o acemic mix u e o s y ene oxide by cycloaddi ion o CO2 ca alyzed by Fe-based chi al ionic liquids 2 and 3.a En y Ca alys T (ºC) Time (h) Con . (%)b Selec i i y (%)c % ee (epoxide)d 1 5 R.T. 24 58 85 : 12 : 3 4 2 9 0 7 21 77 : 18 : 5 6 a Reagen s and condi ions: 5 mol % o ACMILs, s y ene oxide (1.665 mmol), 24 h, nea and p(CO2) = 2.0 ba . b Con e sions de e mined by 1H NMR spec oscopy and e e o he selec i e con e sion o s y ene oxide (a e age o wo uns).c % selec i i y e e ed o A : B : C. d %ee we e de e mined by GC (a e age o wo uns). CONCLUSIONS We p esen he syn hesis and cha ac e iza ion o ou based on di e en imidazolium ca ions. These compounds we e used as enan ioselec i e p ecu so s o p epa e i e acidic chi al pa amagne ic ionic liquids h ough an easy syn he ic me hod. The ob ained ACMILs we e ully cha ac e ized using pola ime y, ICP-OES, EA, and UV- is, ATR FT- IR and Raman spec oscopies. In addi ion, he magne ic p ope ies o hese chi al i on- based ionic liquids we e s udied, showing a Fe3+ oxida ion s a e wi h a magne ic spin S = 5/2. UV- is measu emen s co obo a e he p esence o he [FeX4]- anion in all he ACMILs, while Raman s udies con i m a e ahed al symme y o his species. We ha e also pe o med he he mal cha ac e iza ion o hese no el ACMILs by TGA and DSC, which display liquid physical s a e and high he mal s abili y (up o 200 ºC). These new ACMILs combine simul aneously he op ical, magne ic and acidic p ope ies o [FeX4]- anions wi h he chi al ea u es o imidazolium ca ions. Such in e es ing p ope ies en isage a new app oach o de elop ACMILs wi h applica ions in enan ioselec i e ca alysis (e.g. CO2 ixa ion in o cyclic ca bona es) o chi al ecogni ion agen s, among o he s. AUTHOR INFORMATION Co esponding Au ho s *E-mail: mm[email p o ec ed] (Ca men Ma ín). 17 *E-mail: is ael.cano ico@no ingham.ac.uk (Is ael Cano) ORCID Ca men Ma ín: 0000-0001-8687-6887 Is ael Cano: 0000-0003-3727-9327 CONFLICTS OF INTEREST The e a e no con lic s o in e es o decla e. ACKNOWLEDGMENTS Financial suppo om he Spanish Minis e io de Ciencia e Inno ación (P ojec s MAT2014-55049-C2-R and MAT2016-75883-C2-1-P) and Uni e sidad del País Vasco/Euskal He iko Unibe si a ea (GIU17/50 and PPG17/37). Ca men Ma ín is g a e ul o he P oyec o Puen e con oca o ia 2018 om Uni e sidad de Can ab ia inanced by SODERCAN and VI PPIT-2018 om Uni e sidad de Se illa. Is ael Cano acknowledges inancial suppo om he Eu opean Communi y h ough a Ma ie Skłodowska-Cu ie Indi idual Fellowships (IF-EF; P og amme/Call: H2020-MSCA-IF- 2015; P oposal No: 704710–Sdchi nanoca ). NOTES AND REFERENCES 1 K. Dong, X. Liu, H. Dong, X. Zhang, S. Zhang, Mul iscale s udies on ionic liquids, Chem. Re ., 2017, 117, 6636-6695, DOI: 10.1021/acs.chem e .6b00776. 2 P. Wasse scheid, T. Wel on, Ionic liquids in syn hesis, John Wiley & Sons, 2008, DOI: 10.1002/9783527621194. 3 M. Galinski, A. Lewandowski, I. S epniak, Ionic liquids as elec oly es, Elec ochim. 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