Polyethylene glycol functionalized dicationic ionic liquids with alkyl or

Polyethylene glycol functionalized dicationic ionic liquids with alkyl or polyfluoroalkyl substituents as high temperature lubricants

Chuan-Ming Jin,a Chengfeng Ye,a Benjamin S.Phillips,b Jeffery S.Zabinski,c Xuqing Liu,d Weimin Liu d and Jean’ne M.Shreeve *a

Received 16th December 2005,Accepted 24th January 2006

First published as an Advance Article on the web 6th February 2006DOI:10.1039/b517888f

A series of new polyethylene glycol functionalized dicationic ionic liquids with alkyl or

polyfluoroalkyl substitutents (9–17and 19–24)has been prepared.Important physical properties of these liquids,including glass transition (T g )and decomposition temperatures (T d ),solubility in common solvents,density (d )and viscosity (g ),were measured.These ionic liquids show high thermal stability and good lubricity.In general,imidazolium based dicationic liquids have higher T d (>415u C)than their triazolium analogues.The introduction of polyfluoroalkyl groups boosts antiwear properties but also leads to a decrease in T d .These ionic liquids also exhibit excellent tribological characteristics even at 300u C,which suggests use as high temperature lubricants.

Introduction

In recent years,ionic liquids have received a considerable upswing of interest as new green solvent systems in the fields of organic reactions,1separation technologies,2electrochemical devices,3materials chemistry,4and even as systems in which the spinning of natural fibers such as silk may be improved.5They have intrinsically useful properties,such as negligible volatility,non-flammability,high thermal stability,low melt-ing point,broad liquid range and controlled miscibility with organic compounds,etc.,which make them particularly attractive.Given the wide range of possible cation and anion combinations,the ionic components were easily modified by specific functional groups to allow for a large variety of very useful application related ionic liquids.6

Recently,it was shown,by using inverse gas chromato-graphy with flame ionization or mass spectrometric detection,that geminal dicationic ionic liquids linked by alkyl chains show much higher thermal stability than the most common ionic liquids.7There are civilian and military needs for new lubricant materials for aircraft,spacecraft,and microelectro-mechanical systems (MEMS)devices.The turbine engines and vertical lift systems of advanced military aircraft will require lubricants that function reliably between 240u C to +330u C for >4000hours.8Current aircraft lubricants can only be used up to +150u C.Preliminary research has identified ionic liquids as promising lubricants on a wide variety of materials including:steel,aluminium,copper,silicon,silicon dioxide,silicon nitride,aluminium oxide,and sialon ceramics.9

In fact ionic liquids have been reported as out performing phosphazene and perfluoropolyethers and can significantly reduce the running-in period and friction for metals,engineer-ing ceramics,and MEMS.10In the field of ionic liquids,our interests center on the development of some new polyfluoroalkyl-containing ionic liquids based on imidazo-lium,11triazolium,12tetrazolium,morpholinium or oxazolidi-nium 13cations,and studying their applications in catalytic organic synthesis,14as energetic materials,15and as lubri-cants.16Given that the existence of polyether chains can apparently improve tribological performance,17in this work,we report the preparation of a series of geminal dicationic ionic liquids bridged by different polyethylene glycol chains.18

Results and discussion

Polyethylene glycol functionalized dicationic ionic liquids (9–17and 19–24)were synthesized as shown in Schemes 1and 2.Polyethylene glycol dibromides (5–8)were prepared in y 50–70%yields following a literature method.19They were further treated with two equivalents of 1-methylimidazole,1,2-dimethylimidazole or 1-butyltriazole,respectively,under neat reaction conditions,to form dicationic bromides bridged by polyether linkage chains in high yields.

With the exception of one compound containing one ether linkage chain (solid),the diimidazolium bromide derivatives are sticky colorless liquids.Ditriazolium bromide derivatives are invariably colorless solids that dissolve easily in acetone and methanol.In general,to ensure complete reaction,quaternization of 1-butyltriazole with polyethylene glycol bromides (5–8)required a higher reaction temperature (110u C)and longer reaction time (20h)than for imidazoles.All of the bromides were further reacted with a slight excess of LiN(SO 2CF 3)2(LiNTf 2)(2.2equivalents)in methanol and water (10:1)at room temperature to afford geminal dicationic liquids with polyether linkage chains (9–17)(Scheme 1)in high yields.

a

Department of Chemistry,University of Idaho,Moscow,Idaho,83844-2343,USA b

Universal Technology Corporation,1270North Fairfield Road,Dayton,Ohio 45432-2600,USA c

Air Force Research Laboratories,Materials and Manufacturing

Directorate,Nonmetallic,Materials Division,Nonstructural Materials Branch,Wright-Paterson AFB,Ohio 45433-7750,USA d

Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Lanzhou 730000,P.R.China

PAPER https://www.360docs.net/doc/f18734368.html,/materials |Journal of Materials Chemistry

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In order to introduce additional alkyl or polyfluoroalkyl groups into the dication,we first prepared 1,11-diimidazolium-3,6,9-trioxaundecane (18),a light-yellow liquid,in 57%yield (Scheme 2).The 1,11-dibromide-3,6,9-trioxaundecane (7)was reacted with imidazole based on a slight modification of the literature method.20Subsequently,18was quaternized with excess alkyl halide or polyfluoroalkyl halide under neat reaction conditions and,without further purification,the halide derivatives underwent metathesis reactions with a slight excess of LiN(SO 2CF 3)2(2.2equivalents)to form the corresponding geminal dicationic liquids that contain poly-ether linkage chains 19–24in good yields.Due to the influence of the fluorine atoms in the polyfluoroalkyl groups,CH 2CH 2CF 3and CH 2CH 2C 4F 9,on the electrophilicity of the b carbon,quaternization with these electrophiles proceeds with greater difficultly than with their alkyl analogues.21

Ionic liquids (9–17,19–24)were characterized by their 1H,13

C and 19F NMR spectra,and elemental analyses.The solubilities of the dicationic ionic liquids with NTf 22anions were determined at room temperature.In general,they are immiscible with hexane,diethyl ether,water and miscible with methanol,acetone and ethyl acetate.Ionic liquids that contain polyfluoroalkyl groups,[C 3F 3O 3IM][NTf 2](20),[C 4F 3O 3IM][NTf 2](22),and [C 6F 9O 3IM][NTf 2](24)are immiscible with dichloromethane and chloroform.Ionic liquids [CH 3O 1IM][NTf 2](9)and [CH 3O 2IM][NTf 2](10)comprised of one or two ether linkage chains and 3-methyl-imidazolium rings do not dissolve in dichloromethane.In contrast,[CH 3O 3IM][NTf 2](11)and [CH 3O 4IM][NTf 2](12)having chains terminating in 3-methylimidazolium rings with

three or four ether linkage chains are partly miscible in CH 2Cl 2.Other dicationic ionic liquids 14–17,19,21and 23with cation components containing propyl,butyl and hexyl groups are very soluble in CH 2Cl 2.These results are consistent with the usual influence of polyfluoroalkyl and alkyl sub-stituents on the solubility of ionic liquids.

The thermal properties of these dicationic ionic liquids were determined by differential scanning calorimetry (DSC)and thermal gravimetric analysis (TGA).The fundamental properties including density (d )and dynamic viscosity (g )at different temperatures (30u C and 60u C)are presented in Table 1.All of the new ionic liquids have low glass transition temperatures (T g )in the range of 232u C to 264u C.The length of the linkage polyether chains separating the geminal dications (ranging from one ether to four ether chains)and the nature of the dication (imidazolium 9–13versus triazolium 14–17)appear not to influence their glass transition tempera-tures,e.g.,9–13with T g =247u C to 252u C and 14–17with T g =243u C to 254u C.These results are slightly different than the observations described in the literature,where the length of alkyl chain links was found to affect the melting points of the various geminal dicationic ionic liquids.7In our case where the anion is invariably NTf 22,an anion whose negative charge is dispersed over its entirety,the cation–anion interactions are reduced resulting in lower glass transition temperatures of approximately the same value.Dicationic ionic liquids containing polyether linkage chains have lower glass transition temperatures than analogues with alkyl links where,e.g.,C 12(MIM)2–NTf 2T g =226u C and C 9(MIM)2–NTf 2with T g =214u C.7However,the

glass

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transition temperatures of dicationic ionic liquids (19–24)containing the same linkage ether chains with different alkyl substituents at the 3-position on the imidazolium ring are significantly different.Not surprisingly,T g decreased with the increase of the length of alkyl substituent,for example,[C 3H 7O 3IM][NTf 2]19,[C 4H 9O 3IM][NTf 2]21and [C 6H 13O 3IM][NTf 2]23containing three ether chains with propyl,butyl and hexyl groups at the 3-position of the imidazolium ring have T g at 240u C,262u C and 264u C,respectively.The polyfluoroalkyl substituted analogues,

[C 3F 3O 3IM][NTf 2]

20,[C 4F 3O 3IM][NTf 2]22and [C 6F 9O 3IM][NTf 2]24,have higher phase transition tempera-tures,e.g.,20at 232u C;22at 234u C;and 24at 237u C .Dicationic ionic liquid [2CH 3O 3IM][NTf 2]13with two methyl groups at the 2and 3-positions on the imidazolium ring has one of the lowest glass transition temperatures at 256u C and the greatest thermal stability.Thermal stability is a very important factor for evaluating ionic liquids.From Table 1,it is seen that diimidazolium ring-containing ionic liquids (9–13,19,21and 23)have decomposition temperatures (T d ),>415u C,which are significantly higher than those that were observed for many traditional imidazolium-based ionic liquids.22These triazolium ring-containing ionic liquids (14–17)have lower decomposition temperatures,348u C to 362u C,than their imidazolium analogues.When poly-fluoroalkyl groups replaced the corresponding alkyl groups at the 3-position of the imidazolium ring,the decomposition temperatures of the ionic liquids [C 3F 3O 3IM][NTf 2]20,[C 4F 3O 3IM][NTf 2]22and [C 6F 9O 3IM][NTf 2]24are reduced to ,400u C with T d at 388u C,393u C and 386u C,respectively,i.e.,y 30u C lower than their corresponding alkyl analogues (19,21,23).These results are contrary to our previous reports on the system of dicationic ionic liquids with pincer structures.23

As shown in Table 1,the ionic liquids have moderate densities falling in the range of 1.43g cm 23to 1.71g cm 23.The viscosities are also listed in Table 1.Before measuring their viscosity,all ionic liquids were dried at 60–70u C for 12hours under vacuum.24At 30u C,viscosities range between 327and 1539cP with 9,14,22and 24being too viscous to be measured.The viscosities decrease to between 73and 298cP when the temperature was increased to 60u C.The viscosities of 11,19,21and 23that contain the same bridged polyether chain decrease with increasing length of alkyl substituent chain,e.g.,11(methyl)g =854,135cP,19(propyl)g =512,95cP,21(butyl)g =459,91cP,and 23(hexyl)g =327,71cP at 30and 60u C,respectively (Table 1).The bridging polyether chains have an irregular influence on their viscosity.The viscosities of the ionic liquids are determined essentially by van der Waals interactions,hydrogen bonding,and freedom of molecular rotation.Alkyl chain lengthening and fluorination make the ionic liquids more viscous,due to increased van der Waals interactions.The ionic liquid containing a poly-fluoroalkyl group [C 3F 3O 3IM][NTf 2]20has g =1539cP at 30u C is much higher than 19.[C 4F 3O 3IM][NTf 2]22and [C 6F 9O 3IM][NTf 2]24are too viscous to measure.At 60u C,the viscosities are measurable with 20,g =192cP,22,g =243cP,and 24,g =298cP.The polyfluoroalkyl substituents replacing the analogous alkyl groups increased not only the glass transition temperature and density but also the viscosity.Methylation at the 2,3-positions in the imidazolium ring ([2CH 3O 3IM][NTf 2]13)reduced the viscosity (g =409cP at 30u C and g =80cP at 60u C)as it did the T g .This fact is consistent with hydrogen bonding suppression due to the presence of methyl groups.

In order to determine the tribological properties,four compounds were chosen for Optimol SRV (Schwingungs–Reibverschleiss–Pruefgeraet)tribology testing.9As indicated,the ionic liquid with more polyether units (17vs.14)shows better antiwear properties under low load,while resulting in high wear under high load (>500Newtons).The result clearly confirms that the existence of fluorine (22vs.21)in the ionic liquids favorably boosts its anti-wear performance (Table 2).In addition,two thermally stable ionic liquids (13,19)were used as candidates for a temperature ramp test,where pure ionic liquids were put onto the surface of a steel vs.steel contact (M50steel)and the temperature increased every 5000cycles.The friction for ionic liquid 13at 25u C is very consistent,and an increase to 100u C causes a slight reduction due to a decrease in viscosity.At 200u C the continuing decrease in viscosity will cause increasing asperity contact and possibly the first signs of reaction which leads to the increased friction.At >300u C,the surface reaction between the steel and the ionic liquid causes the friction to increase dramatically.

Table 1Physical and thermal properties of geminal dicationic ionic liquids 9–17and 19–24

Compd a T g (u C)b T d (u C)c Density d Viscosity e

30u C 60u C 9[CH 3O 1IM][NTf 2]249420 1.64—20710[CH 3O 2IM][NTf 2]252430 1.625629211[CH 3O 3IM][NTf 2]247426 1.5385413512[CH 3O 4IM][NTf 2]252429 1.5270511913[2CH 3O 3IM][NTf 2]256457 1.554098014[C 4H 9O 1TA][NTf 2]243362 1.51—21915[C 4H 9O 2TA][NTf 2]254365 1.4855410216[C 4H 9O 3TA][NTf 2]248352 1.4861810417[C 4H 9O 4TA][NTf 2]248348 1.477279719[C 3H 7O 3IM][NTf 2]240427 1.605129520[C 3F 3O 3IM][NTf 2]232388 1.68153919221[C 4H 9O 3IM][NTf 2]262438 1.474599122[C 4F 3O 3IM][NTf 2]234393 1.60—24323[C 6H 13O 3IM][NTf 2]264415 1.433277124

[C 6F 9O 3IM][NTf 2]

237

386

1.71

—

298

a

For convenience,special notations were used.For example,[CH 3O 1IM][NTf 2]represents ionic liquid (9)with one ether linkage chain (O 1),imidazolium cation (IM)and methyl group at 3-position of the imidazolium ring;while [C 4H 9O 1TA][NTf 2]represents ionic liquid (14)with one ether linkage chain (O 1),triazolium cation (TA)and a butyl group at the 1-position of the triazolium ring.b Glass transition temperature.c Decomposition temperature.d g cm 23at 25u C.e Determined by drop-ball method (g /cP).

Table 2

SRV anti-wear properties of selected ionic liquids Compd.Worn volume/61024cm 3under different loads

200N 300N 400N 500N 600N 14 6.815.519.017.521.517 5.87.710.619.422.5218.410.012.014.015.522

6.2

6.0

9.0

9.0

8.0

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Ionic liquid 19was demonstrated to be much better than 13and other most common ionic liquids by lasting and performing well through the 300u C tests.This result indicates that during operation at elevated temperatures,this ionic liquid can form thin,durable and stable surface boundary layers that maintain low friction and wear (Fig.1).

In conclusion,a new series of polyethylene glycol function-alized dicationic ionic liquids containing alkyl or polyfluoro-alkyl groups (9–17and 19–24)has been prepared,and their glass transition (T g )and decomposition temperatures (T d ),solubility in common solvents,density (d )and viscosity (g )measured.The effect of different linkage polyether groups (from one ether chain to four ether chains),alkyl or polyfluoroalkyl substituents and cation type (imidazolium or triazolium)on their physicochemical properties was demonstrated.Geminal dicationic liquids based on imidazolium have higher thermal decomposition temperatures (>415u C)than their triazolium analogues.Introduction of polyfluoroalkyl groups increased the glass transition temperature,density and viscosity.The presence of polyfluoroalkyl groups boosts antiwear properties but also leads to a decrease in T d .These ionic liquids also exhibit excellent tribological characteristics even at 300u C,which suggests use as high temperature lubricants.

Experimental

The chemicals,polyethylene glycol (1–4),1-methylimidazole and alkyl or perfluoroalkyl halide etc.,were obtained commercially.Polyethylene glycol dibromide (5–8),1-butyl-triazole and 1,11-diimidazolium-3,6,9-trioxaundecane (18)were prepared by literature methods.19Silica gel (0.060–0.200mm,pore diameter y 4nm)was used for column chromatography and a standard Schlenk line system was used for some reactions.1H,13C and 19F NMR spectra were recorded in acetone-d 6(unless otherwise stated)on a Bruker AMX spectrometer at 300,75and 282MHz,respectively.Chemical shifts are reported in ppm relative to the appropriate standard,CFCl 3for 19F,and TMS for 1H and 13C NMR spectra.DSC data were recorded by heating from 280u C to 200u C at 10u C min 21using a TA Instruments TA10differential scanning calorimeter equipped with auto-cool and calibrated using indium.Thermogravimetric analysis (TGA)measurements were made using a TA Instruments TA50.Samples were heated at 10u C min 21from 20u C to 500u C in a dynamic nitrogen atmosphere.Density was determined using a pycnometer.Viscosity was obtained by a drop-ball method (Minivis II).Elemental analyses were performed at the Shanghai Institute of Organic Chemistry.

Anti-wear properties were evaluated on an Optimol SRV oscillating friction and wear tester in air.9The upper ball (diameter 10mm,SAE52100)slides reciprocally at amplitude of 1mm against the lower stationary discs (SAE52100).All the tests were conducted at the frequency of 25Hz,and 30min test duration,the corresponding linear speed is 0.1m s 21.Prior to the friction and wear test,two drops of the lubricant were introduced to the ball-disc contact area.The friction coefficient curve was recorded automatically.The wear volume loss of the lower disc was determined by measuring the area and depth of the wear scar using a profilometer.

Temperature-ramp friction and wear testing was performed using a pin-on-disk tribometer.10The tribometer utilizes a stationary1/4in ball on a 1in diameter rotating disk (M50steel).Multiple runs of self-mated samples were performed on each disc,with the test radius varying,keeping the linear speed constant at 0.120m s 21.A constant load of 1N was used in all tests.The samples were run at room temperature in air.

General procedure for the preparation of 9–17

1-Methylimidazole (2mmol),1,2-dimethylimidazole (2mmol)or 1-butyltriazole (2mmol)and polyethylene glycol dibromide (5–8,1mmol)were placed in a Pyrex glass tube,sealed and heated at 80u C for 16h or 110u C for 20h,respectively.After cooling,the reaction mixture was dissolved in methanol (30mL),a solution (3mL)of lithium bis(trifluoromethane-sulfonyl)amide (2.2mmol)was added,and stirred at room temperature for 2h.The organic solvent was removed and extracted with ethyl acetate (3620mL)which was then washed with water (2620mL)and ether (2610mL),and dried over anhydrous magnesium sulfate.The solvent was removed under vacuum at 65u C overnight to give colorless liquid products 9–17

.

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General procedure for the preparation of 19–24

1,11-Diimidazolium-3,6,9-trioxaundecane 18(1mmol)and alkyl or perfluoroalkyl iodide (or bromide)(2.5mmol)were placed in a Pyrex glass tube,sealed and heated at 80u C for 12h or 110u C for 20h when 1H ,1H ,2H ,2H -perfluoro-1-iodohexane or 3,3,3-trifluoropropyl iodide was used.After cooling,the excess alkyl halide was removed under vacuum,the residue was washed with ethyl acetate (2610mL)and CH 2Cl 2(10mL),and dried in vacuum.It was dissolved in methanol (30mL),and a solution (3mL)of lithium bis(trifluoromethanesulfonyl)amide (2.2mmol)was added.The mixture was stirred at room temperature for 2h.The solvent was removed and extracted with ethyl acetate (3620mL).The organic layer was washed with water (2620mL)and ether (2610mL),dried with anhydrous magnesium sulfate,and the organic solvent was removed under vacuum at 65u C overnight to give colorless or light-yellow liquid products (19–24).

1,19-(3-Oxapentane-1,5-diyl)bis(3-methyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](9)

Yield 92.2%;1H NMR d 8.97(s,2H),7.72(s,2H),7.68(s,2H),4.58(t,3J HH =4.6Hz,4H),4.04(s,6H),3.99(t,3J HH =4.6Hz,4H);13C NMR d 137.6,124.4,123.9,120.8[q,1

J CF =319.4Hz,N(SO 2C F 3)2],69.5,50.3,36.6;19F NMR d 279.9[N(SO 2CF 3)2];Anal.Calcd for C 12H 20F 12N 6O 9S 4?5H 2O:C,21.67;H,2.41;N,9.48.Found:C,21.39;H,2.30;N,9.44%.

1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis(3-methyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](11)Yield 93.1%;1H NMR d 8.99(s,2H),7.74(s,2H),7.67(s,2H),4.53(t,3J HH =4.8Hz,4H),4.04(s,6H),3.93(t,3J HH =4.8Hz,4H), 3.60–3.69(m,8H);13C NMR d 137.5,124.1,123.7,120.6[q,1J CF =319.2Hz,N(SO 2C F 3)2],70.6,70.5,69.1,49.1,35.3;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 20H 28F 12N 6O 11S 4?3H 2O:C,25.56;H,3.63;N,8.95.Found:C,25.30;H,3.08;N,8.86%.

1,19-(3,6,9,12-Tetraoxatetradecane-1,14-diyl)bis(3-methyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](12)Yield 91.2%;1H NMR d 9.01(s,2H),7.76(s,2H),7.69(s,2H),4.52(t,3J HH =4.8Hz,4H),4.06(s,6H),3.92(t,3J HH =4.8Hz,4H),3.60–3.69(m,12H);13C NMR d 137.8,124.0,123.0,120.2[q,1J CF =319.0Hz,N(SO 2C F 3)2],70.9,70.8,70.7,69.2,50.4,36.6;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 22H 32F 12N 6O 12S 4%3H 2O:C,26.89;H, 3.90;N,8.55.Found:C,26.72;H,3.30;N,8.56%.

1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis(2,3-dimethyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](13)Yield 91.2%;1H NMR d 7.62(s,2H),7.57(s,2H),4.47(t,3

J HH =4.9Hz,4H),3.95(s,6H),3.90(t,3J HH =4.9Hz,4H),3.54–3.63(m,8H),2.78(s,6H);13C NMR d 123.1,122.3,120.6[q,1J CF =319.2Hz,N(SO 2C F 3)2],118.8,71.5,70.9,69.7,49.2,35.5,9.9;19F NMR d 279.8[N(SO 2C F 3)2];Anal.Calcd for

C 22H 32F 12N 6O 11S 4?2H 2O:C,27.85;H,3.82;N,8.86.Found:C,27.91;H,3.47;N,8.74%.

4,49-(3-Oxapentane-1,5-diyl)bis(1-butyl-1H -triazolium-4-yl)di[bis(trifluoromethanesulfonyl)amide](14)

Yield 89.2%;1H NMR d 10.02(s,2H),9.12(s,2H),4.79(t,3

J HH =4.4Hz,4H),4.55(t,3J HH =7.2Hz,4H),4.10(t,3J HH =4.4Hz,4H), 1.96–1.99(m,4H), 1.38–1.46(m,4H),0.95(t,3J HH =7.4Hz,6H);13C NMR d 146.0,143.2,120.8[q,1

J CF =319.0Hz,N(SO 2C F 3)2],68.9,53.1,49.0,31.3,19.9,13.6;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 20H 30F 12N 8O 9S 4:C,27.21;H,3.43;N,12.69.Found:C,27.07;H,3.69;N,12.72%.

4,49-(3,6-Dioxaoctane-1,8-diyl)bis(1-butyl-1H -triazolium-4-yl)di[bis(trifluoromethanesulfonyl)amide](15)

Yield 90.8%;1H NMR d 9.99(s,2H),9.07(s,2H),4.71(t,3

J HH =4.5Hz,4H),4.56(t,3J HH =7.2Hz,4H),4.01(t,3J HH =4.5Hz,4H),3.75(s,2H),1.94–1.99(m,4H),1.37–1.45(m,4H),0.95(t,3J HH =7.4Hz,6H);13C NMR d 145.8,143.1,120.7[q,1J CF =319.2Hz,N(SO 2C F 3)2],70.6,68.5,52.9,49.1,31.2,19.7,13.4;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 22H 34F 12N 8O 10S 4:C,28.51;H,3.70;N,12.09.Found:C,28.25;H,3.95;N,12.13%.

4,49-(3,6,9-Trioxaundecane-1,11-diyl)bis(1-butyl-1H -triazolium-4-yl)di[bis(trifluoromethanesulfonyl)amide](16)

Yield 91.5%;1H NMR d 9.97(s,2H),9.11(s,2H),4.71(t,3

J HH =4.6Hz,4H),4.55(t,3J HH =7.2Hz,4H),3.99(t,3J HH =4.6Hz,4H),3.64–3.74(m,8H),1.94–2.00(m,4H),1.35–1.47(m,4H),0.95(t,3J HH =7.4Hz,6H);13C NMR d 145.9,143.1,120.7[q,1J CF =319.2Hz,N(SO 2C F 3)2],70.7,70.6,68.4,52.9,48.9,31.2,19.7,13.4;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 24H 38F 12N 8O 11S 4:C,29.69;H,3.95;N,11.54.Found:C,29.47;H,3.96;N,11.48%.

4,49-(3,6,9,12-Tetraoxatetradecane-1,14-diyl)bis(1-butyl-1H -triazolium-4-yl)di[bis(trifluoromethanesulfonyl)amide](17)Yield 87.6%;1H NMR d 9.99(s,2H),9.11(s,2H), 4.68(t,3J HH =4.6Hz,4H),4.56(t,3J HH =7.2Hz,4H),3.98(t,3

J HH =4.6Hz,4H),3.65–3.72(m,12H),1.96–1.99(m,4H),1.36–1.46(m,4H),0.96(t,3J HH =7.4Hz,6H);13C NMR d 145.8,143.2,120.7[q,1J CF =319.2Hz,N(SO 2C F 3)2],70.8,70.7,70.6,68.4,52.9,48.9,31.2,19.7,13.4;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 26H 42F 12N 8O 12S 4?H 2O:C,30.20;H,4.26;N,10.84.Found:C,29.88;H,4.23;N,10.98%.

1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis(3-propyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](19)Yield 92.7%;1H NMR d 9.04(s,2H),7.78(s,2H),7.75(s,2H),4.54(t,3J HH =4.9Hz,4H),4.34(t,3J HH =7.3Hz,4H ),3.95(t,3J HH =4.9Hz,4H),3.61–3.68(m,8H),1.96–2.01(m,4H),0.97(t,3J HH =9.6Hz,6H);13C NMR d 136.8,123.9,122.9,120.6[q,1J CF =319.4Hz,N(SO 2C F 3)2],70.7,70.6,69.0,51.7,50.3,23.8,10.4;19F NMR d 279.8[N(SO 2C F 3)2];Anal.Calcd

D o w n l o a d e d b y S o u t h w e s t U n i v e r s i t y o n 12/05/2013 08:43:06. P u b l i s h e d o n 06 F e b r u a r y 2006 o n h t t p ://p u b s .r s c .o r g | d o i :10.1039/B 517888F

for C 24H 36F 12N 6O 11S 4:C,30.64;H,3.86;N,8.93.Found:C,30.31;H,3.98;N,8.05%.

1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis[3-(3,3,3-trifluoropropyl)-1H -imidazolium-1-yl]

di[bis(trifluoromethanesulfonyl)amide](20)

Yield 86.4%;1H NMR d 9.05(s,2H),7.76(s,2H),7.70(s,2H),4.64(t,3J HF =6.9Hz,4H),4.47(t,3J HH =4.9Hz,4H ),3.89(t,3J HH =4.9Hz,4H),3.58–3.65(m,8H),2.98–3.10(m,4H);13

C NMR d 137.6,124.3,123.2,126.6[q,1J CF =274.6Hz,CH 2C F 3],120.7[q,1J CF =319.2Hz,N(SO 2C F 3)2],70.8,70.7,69.1,50.6,43.8[q,3J CF =4.0Hz ,CH 2CH 2CF 3],34.4[q,2

J CF =29.3Hz ,CH 2CF 3];19F NMR d 279.8[s,12F,N(SO 2C F 3)2]265.8(t,3J HF =10.0Hz,6F,CH 2C F 3);Anal.Calcd for C 24H 30F 18N 6O 11S 4:C,27.49;H, 2.88;N,8.01.Found:C,27.43;H,3.04;N,7.50%.

1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis(3-butyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](21)Yield 93.8%;1H NMR d 9.04(s,2H),7.78(s,2H),7.76(s,2H),4.53(t,3J HH =5.0Hz,4H),4.36(t,3J HH =7.4Hz,4H ),3.94(t,3J HH =5.0Hz,4H),3.60–3.69(m,8H),1.87–1.97(m,4H),1.31–1.44(m,4H),0.94(t,3J HH =9.5Hz,6H);13C NMR d 137.1,124.1,123.1,121.2[q,1J CF =319.2Hz,N(SO 2C F 3)2],70.9,70.8,69.3,50.4,50.2,32.6,19.8,13.6;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 26H 40F 12N 6O 11S 4:C,32.23;H,4.16;N,8.67.Found:C,32.22;H,4.35;N,8.52%.1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis[3-(4,4,4-trifluorobutyl)-1H -imidazolium-1-yl]

di[bis(trifluoromethanesulfonyl)amide](22)

Yield 90.3%;1H NMR d 8.97(s,2H),7.71(s,2H),7.66(s,2H),4.41–4.48(m,8H),3.90(t,3J HH =4.8Hz,4H),3.58–3.65(m,8H),2.21–2.28(m,8H);13C NMR d 136.9,127.3(q,1J CF =273.6Hz,C F 3),124.1,122.8,120.1[q,1J CF =319.5Hz,N(SO 2C F 3)2],70.6,70.4,68.9,50.2,48.8,30.7(q,2J CF =110.2Hz,C H 2CF 3),23.3(q,3J CF =12.4Hz,C H 2CH 2CF 3);19F NMR d 279.8[s,12F,N(SO 2C F 3)2],266.8(t,3J HF =10.2Hz,6F,CH 2C F 3);MS (solid probe)m /z =798.10[for cation].1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis(3-hexyl-1H -imidazolium-1-yl)di[bis(trifluoromethanesulfonyl)amide](23)Yield 89.9%;1H NMR d 9.05(s,2H),7.79(s,2H),7.76(s,2H),4.53(t,3J HH =4.8Hz,4H),4.37(t,3J HH =7.2Hz,4H ),3.95(t,3

J HH =4.8Hz,4H),3.61–3.68(m,8H),1.95(bs,4H),1.34(bs,12H),0.87(t,3J HH =7.1Hz,6H);13C NMR d 136.8,123.8,122.9,120.6[q,1J CF =319.4Hz,N(SO 2C F 3)2],70.7,70.6,70.5,69.1,50.3,31.4,30.4,26.1,22.7,13.8;19F NMR d 279.9[N(SO 2C F 3)2];Anal.Calcd for C 30H 48F 12N 6O 11S 4?2H 2O:C,33.93;H,4.90;N,7.92.Found:C,33.79;H,4.56;N,7.93%.1,19-(3,6,9-Trioxaundecane-1,11-diyl)bis[3-(3,3,4,4,5,5,6,6,6-nonafluorohexyl)-1H -imidazolium-1-yl]di[bis(trifluoromethanesulfonyl)amide](24)

Yield 87.1%;1H NMR d 9.20(s,2H),7.92(s,2H),7.81(s,2H),4.84(t,3J HH =7.1Hz,4H),4.56(t,3J HH =4.6Hz,4H ),3.95

(t,3J HH = 4.6Hz,4H), 3.59–3.68(m,8H), 3.03–3.16(m,4H);19F NMR d 279.9[12F,N(SO 2C F 3)2],281.9(6F),2114.6(4F),2124.9(4F),2126.6(4F);Anal.Calcd for C 30H 30F 30N 6O 11S 4:C,26.71;H, 2.24;N, 6.23.Found:C,26.28;H,2.27;N,6.58%.

Acknowledgements

We gratefully acknowledge the support of the National Science Foundation (Grant CHE-0315275),AFOSR (Grant F49620-03-1-0209)and ONR (Grant N00014-02-1-0600).

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