The Gelation Ability and Morphology Study of Organogel System Based on Calamitic Hydrazide Derivatives

The gelation property of a series of LMOG bearing hydrazide and azobenzene groups, namely, N-4-(alkoxyphenyl)-N'-4-[(4-methoxyphenyl)azophenyl] benzohydrazide (BNBC-n, n=8,12,14), has been systematically studied in this work. The obtained results demonstrate that the gelling ability in organic solvents is significantly influenced by the length of terminal alkoxy chain. In different organic solvents, it is hard to observe the organogel formation for BNBC-8 molecule. On the contrary, the organogelators BNBC-12 and BNBC-14 bearing longer terminal chains have shown great ability to gel organic solvents to form stable organogels. The critical gelation concentration for BNBC-12 reaches as low as 5.3 × 10^-3 M, which can be considered as a supergelator. It has been manifested that the aggregation morphology of organogel strongly depends on the nature of the gelling solvents and the length of the terminal alkoxy chain. The gelation of BNBC-n provides an easy method for the preparation of multidimensional structure and manipulation of morphology from ribbons, hollow tube fiber to 3D net-like structure in different solvents. The cooperation of hydrogen bonding, π-π interaction, and Van der Waals force is suggested to be the main contribution to this self-assembled structure.