The synthesis of 4'-hydroxyphenyl(4-hydroxy-3-allyl)azobenzene is reported. The mol. is mesogenic and it can be used for prepg. nematic main-chain segmented polymers. The nematic phase is the result of the effect of the side allyl group which, while it destabilizes the cryst. phase, does not affect the occurring of the nematic order. In the cryst. state, a large hexagonal unit cell contg. five to six chains is obsd. for polymers with a longer flexible spacer in the chain. Chloroform solns. and thin films of polymers absorb in the UV-visible range, at approx. 332 and 439 nm, corresponding to the _______ and _____ electronic transitions of azo arom. chromophores, resp. Under appropriate UV irradn. we have obtained the photoisomerizations trans-cis and cis-trans, which are fully reversible in the case of solns. In the solid state a photostationary state is reached
Synthesis and characterization of segmented liquid crystalline polymers with the azo group in the main chain.
Amendola E;
2004
Abstract
The synthesis of 4'-hydroxyphenyl(4-hydroxy-3-allyl)azobenzene is reported. The mol. is mesogenic and it can be used for prepg. nematic main-chain segmented polymers. The nematic phase is the result of the effect of the side allyl group which, while it destabilizes the cryst. phase, does not affect the occurring of the nematic order. In the cryst. state, a large hexagonal unit cell contg. five to six chains is obsd. for polymers with a longer flexible spacer in the chain. Chloroform solns. and thin films of polymers absorb in the UV-visible range, at approx. 332 and 439 nm, corresponding to the _______ and _____ electronic transitions of azo arom. chromophores, resp. Under appropriate UV irradn. we have obtained the photoisomerizations trans-cis and cis-trans, which are fully reversible in the case of solns. In the solid state a photostationary state is reachedI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
