Design and synthesis of coordination polymer gels and high dichroic ratio azo dyes

Abstract

Here we report the first example of catalytic metallogels, which are formed irreversibly in dimethylsulfoxide (DMSO) via the creation of cross-linked and three-dimensional coordination polymeric networks by using transition metal ions and multi-dentate ligands, Conformational flexibility of the ligands and slow formation of the coordination polymers apparently favor the gelation. This new soft materials will provide a new playground in coordination chemistry to study and utilize other functions of coordination polymers

These novel and stable metallogels consists of a coordination polymeric network and an amphiphilic organic solvent, are stable in water and most organic solvents, can catalyze the oxidation of benzyl alcohol to benzaldehyde by using their Pd(II) moieties as the catalytic centers. The best catalytic turnover of the metallogel is twice that of Pd(OAc)2 in the similar reaction condition.

A series of azo-containing compounds, which contains monomer, dimer and polymeric precursor were synthesized and characterized. They can potentially act as photo-alignment on liquid crystal display (LCD) via photochemical trans-cis-trans isomerization of the azo group. We synthesized the azo-containing compound with elongated shape intended to provide better photo-alignment for LCDs. We investigated the suitability of being optical alignment by measuring the dichroic ratio. We found out that most of our new compounds are not dissolved in liquid crystal, which is the first criterion to be an alignment. As the technology restrictions, we lack the techniques in measuring the dichroic ratio at this moment, but we will measure it in the foreseeable future. We also plan to synthesize azo-containing polymer as it can provide extra chemical and photochemical stability.

Date of Award	2002
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology