Tubular and lamellar hydrogen-bonding molecular assemblies of isophthalic acid derivatives bearing a –CONHCnH2n+1 chain

摘要

Isophthalic acid derivatives ( CnIP ), bearing alkylamide chains (–CONHC _( n ) H _(2 n +1) : n = 6, 10, 14, and 18) at the 5-position that can participate in hydrogen bonding, were prepared and evaluated for their hydrogen-bonding molecular assembly structures for organogelation and liquid crystal formation. The hydrogen-bonding carboxylic acid (–COOH) groups form a ring-shaped ( CnIP ) _(6) hexamer or a one-dimensional (1D) zig-zag ( CnIP ) _(∞) chain. Although neither organogelation nor liquid crystal formation was observed in the isophthalic acid derivative bearing an alkoxy (–OC _(14) H _(29) ) chain, C14IP and C18IP derivatives could form both organogel and liquid crystal states through intermolecular N–H?O = amide-type hydrogen-bonding interactions. A discotic hexagonal columnar liquid crystal (Col _(h) ) phase was observed in hydrated ( C14IP ) _(6) ·(H _(2) O) _( n ) and ( C18IP ) _(6) ·(H _(2) O) _( n ) , whereas a lamella-type liquid crystal (L _(a) ) phase was confirmed in the unhydrated C18IP . In the Col _(h) phase, O–H?O hydrogen-bonding ring-shaped ( C14IP ) _(6) and ( C18IP ) _(6) hexamers assembled to form the tubular molecular assembly stabilized by intermolecular–N–H?O = hydrogen-bonding interactions along the tube growth direction, where H _(2) O molecules were contained within the hydrophilic space. On the other hand, the N–H?O = hydrogen-bonding interactions between the 1D zig-zag ( CnIP ) _(∞) chains formed a layer-type molecular assembly of the L _(a) -phase in the absence of water molecules.