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

Abstract

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 gel-forming compounds and gel-forming properties, a novel family of low-molecular-weight organic compounds containing terthiophene, N,N′-stearyl-5,5″-(2,2′:5′2″-terthiophene)dicarboxamide (DC183T) and N,N′-dialkyl-5,5″-(3,3″-dioctyl-2,2′:5′2″-terthiophene)dicarboxamide (DCn DOc3T, n = 5, 8, 16, 18), were designed and synthesized. Whereas DC183T did not form gels with organic solvents, DCnDOc3T (n = 8, 16, 18) were found to form gels with certain organic solvents. These are the first examples of low-molecular-weight organic gels containing an oligothiophene moiety. It is of interest to note that while DC8DOc3T forms opaque gels with alcohols, e.g. ethanol and isopropanol, DC16DOc3T and DC18DOc3T form transparent gels with hydrocarbon solvents such as heptane, octane, undecane, and others. It is shown that the intermolecular hydrogen bonding and intermolecular interactions between the long alkyl chain in the N-alkylcarboxamide group as well as the incorporation of an alkyl group at the β-position of the thiophene ring play an important role for the formation of gels. The optical micrographs of gels and the SEM images of xerogels showed three-dimensional networks of fibrous bundle structures. Copyright © 2000 John Wiley & Sons, Ltd.