A novel class of low-molecular-weight organic gels based on terthiophene

In order to develop a novel class of low-molecular-weight organic gels and to gain an insight into the relationship between molecular structures of ge l-forming compounds and gel-forming properties, a novel family of low-molec ular-weight organic compounds containing terthiophene, N,N'-stearyl-5,5 "-( 2,2':5'2 " -terthiophene)dicarboxamide (DC(18)3T) and N,N'-dialkyl-5,5 "-(3 ,3 " -dioctyl-2,2':5'2 " -terthiophene)dicarboxamide (DC(n)DOc3T, n = 5, 8, 16, 18), were designed and synthesized. Whereas DC(18)3T did not form gels with organic solvents, DC(n)DOc3T (n = 8, 16, 18) were found to form gels with certain organic solvents. These are the first examples of low-molecula r-weight organic gels containing an oligothiophene moiety. It is of interes t to note that while DC(8)DOc3T forms opaque gels with alcohols, e.g. ethan ol and isopropanol DC(16)DOc3T and DC(18)DOc3T form transparent gels with h ydrocarbon solvents such as heptane, octane, undecane, and others. It is sh own that the intermolecular hydrogen bonding and intermolecular interaction s between the long alkyl chain in the N-alkylcarboxamide group as well as t he incorporation of an alkyl group at the beta -position of the thiophene r ing play an important role for the formation of gels. The optical micrograp hs of gels and the SEM images of xerogels showed three-dimensional networks of fibrous bundle structures. Copyright (C) 2000 John Wiley & Sons, Ltd.