Investigation On The Synthesis And Property Of Molecular Switch Based On Naphthaldehyde-Hydrazone Derivates

Molecular switch is an application of chemical molecule, which has aroused moreand more interests. Light induced molecular switch has been paid attention to persistently,because of its various species and simple control approaches. Hydrazone derivates haveE/Z isomerization induced by ultraviolet irradiation and heating and could be used asmolecular switch to some extent. A series of2-hydroxy/methoxy-naphthaldehyde-hydrazone derivates were synthesized, and isomerization characteristicsinduced by ultraviolet irradiation、heating and ultrasound approach were investigated.（1） Synthesized five2-hydroxy/methoxy-naphthaldehyde-hydrazone derivates, anddetected the molecular structures by¹H-NMR、¹³C-NMR、FT-IR.（2） These six hydrazone derivates possess E configuration in room temperature andcould convert to Z-isomer by ultraviolet irradiation. Fluorescence intensity decreased in theconversion process and it can decrease77%at most. The rate and ratio of decrease hadrelationship with the molecular structures: molecules with intramolecular H bond、electron-withdrawing groups and poor conjugation had worst conversion rate and ratio. TheZ-isomer could convert to E-isomer induced by heating and ultrasound approach and thefluorescence intensity recovered at the same time. Fluorescence intensity changedperiodically by interval ultraviolet irradiation、heating/ultrasound approach.（3） The isomerization was confirmed by the results of1H-NMR、 COSY andfluorescence spectra, and deduced the structures of these derivates before and after the useof inducing approach as planar and distortion. Made comparison of the series ofphotoisomerization characteristics and selected the best one7e to make further research:the changes of NMR and fluorescence spectra as a function of irradiation time orheating/ultrasound time after uv irradiation for30min. It showed that7e had outstandingisomerization characteristics: high reversing ratio、uv responding rate、 fluorescence intensity and stability，while Z�'E isomerization can be induced by heating and ultrasoundapproach, and the latter was used to induce C=N double bond isomerization for the firsttime to our best knowledge.