RESUMO
Polybenzimidazoles with three different network structures are synthesized by condensation polymerization between the conventional monomer 3,3'-Diaminobenzidine and three different acid monomers. The synthesised polymer networks are characterized using several characterization techniques such as FT-IR, powder XRD, HR-SEM and TG-DTA analyses. The polybenzimidazoles are amorphous in nature with excellent thermal stability up to 450 ºC. The photophysical properties of polybenzimidazoles are studied using UV-visible absorption and Emission spectral techniques. Further, the excited state photoluminescence decay time measurement shows a functional group dependant decay behaviour. All the three polymers display narrow optical band gap energy and could be applied as a material for solar energy conversion and semiconductors.
RESUMO
The interaction of n-(4-hydroxyphenyl)-imidazole with p-sulfonatocalix[4]arene is studied using fluorescence technique. The quenching of fluorescence intensity explains the efficiency of binding via binding constant and quenching constant. The excited state lifetime of n-(4-hydroxyphenyl)-imidazole is decreased upon interaction with p-sulfonatocalix[4]arene. The cyclic voltametric studies emphasized the interaction of n-(4-hydroxyphenyl)-imidazole with p-sulfonatocalix[4]arene. Quantum chemical calculations are carried out to study the interactions as well as charge transfer between the host and the guest upon complexation. The simulations revealed that the n-(4-hydroxyphenyl)-imidazole interacts with p-sulfonatocalix[4]arene with horizontal orientation with in the p-sulfonatocalix[4]arene cavity.
