[The influence of pyridyl-carboxylic acid intermolecular H-bond on photoisomerization and photochemical stabilities].

A new type of liquid crystalline was formed through self-assembly via intermolecular hydrogen bonding between the carboxylic acid and the pyridyl group of the stilbazoles. Cholesteryl butane diacid single ester (CSA) was synthesized for use as H-bond donor and the stilbazole derivatives (NCn) were prepared as H-bond acceptors. The spectroscopic behavior and the photochemical stabilities of these two compounds, NCn and its intermolecular H-bonding complex CSA . NCn were investigated by UV-Vis spectroscopy. The results show that these two compounds easily undergo photoisomerization from trans to cis isomers in alcohol. In chloroform solution, the CSA . NCn only undergoes trans-cis photoisomerization, while NCn exhibits not only trans-cis isomerization but also a special photoreaction. The reason is that in CSA . NCn compounds, the pyridyl N-end group is forms intermolecular H-bonding with CSA, and can't catch the H+ and the radical. It is proved that this intermolecular H-bond was very stable when being exposed to UV light.