Structure-Property Correlation of a New Family of Organogelators Based on Organic Salts and Their Selective Gelation of Oil from Oil/Water Mixtures

摘要

Organic salts based on dicy-clohexylamine and substituted/unsub-stituted cinnamic acid exhibit efficient gelation of organic fluids,including selective gelation of oil from an oil/water mixture.Among the cinnamate salts,dicyclohexylammonium 4-chlorocinna-mate (1),3-chlorocinnamate (2),4-bro-mocinnamate (3),3-bromocinnamate (4),4-methylcinnamate (5) and the parent cinnamate (6) are gelators,whereas 2-chlorocinnamate (7),2-bro-mocinnamate (8),3-methylcinnamate (9),2-methylcinnamate (10) and hydro-cinnamate (11) are non-gelators.Non-gelation behaviour of 11 and various benzoate derivatives 12-18 indicate the significance of an unsaturated backbone in the gelation behaviour of the cinnamate salts.A structure-property correlation based on the single-crystal structures of most of the gelators (1,3,5 and 6) and non-gelators,such as 7,8,10-18,indicates that the prerequisite for the one-dimensional (1D) growth of the gel fibrils is mainly governed by the 1D hydrogen-bonded network involving the ion pair.All the non-gelators show either two- (2D) or zero-dimensional (OD) hydrogen-bonded assemblies involving the ion pair.The molecular packing of the fibres in the xerogels of 1,3,5 and 6 has also been established on the basis of their simulated powder diffraction patterns,XRPD of bulk solids and xerogels.Ab initio quantum chemical calculations suggests that it-jt interactions is not a contributing factor in the gelation process.