Synthesis And Spectral Properties Investigation Of Schiff Base Dyes With The Function Of The Excited State Intramolecular Proton Transfer(ESIPT)

Just the same as the intramolecular charge transfer(ICT), the excited state intramolecular proton transfer(ESIPT) is the basic processes of the nature,and it refers to organic molecules absorbing photons from the ground state transition to the excited state , ESIPT process occurs between intramolecular detur proton groups and the acceptive proton groups.An important feature of this process is the detur proton groups usually occur Tautomerism, such as enolase occurs from enol transfer to keto tautomerization in the excited state, and lead to the emission wavelength of molecules significant red-shift. Normally such molecules are good fluorescent probe and photochromic materials. Such reactions are great important for the photochemical and photobiological response, at present it is also a hot topic of the experimental and theoretical research.Benzaldehyde condensing of aromatic amine Schiff base compounds and their derivatives were chosen as the target of this study, were designed and synthesized a series of Schiff base photosensitive Dyes providing with the ability of excited state intramolecular proton transfer and template Dyes molecule without ESIPT. 1HNMR, 13CNMR and elemental analysis were used to characterize them. The photochemical and photophysical properties of compounds were detected by UV absorption spectra, fluorescence emission spectra, fluorescence quantum yield and fluorescence lifetime as well as two-photon upconversion fluorescence emission spectra and two-photon absorption cross section.After a lot of research work, we drew some conclusions as following:1.Benzaldehyde condensing of aromatic amine schiff base compounds and their derivatives, in particular its compounds containing adjacent hydroxyl group, possess good capability of ESIPT. In the issue, not only ESIPT was detected through the structure of branched and hyperbranched molecular chemistry, but also adjustablity and controllablity was achieved in molecular level.2.The derivatives with two-styrene fragment connecting with benzaldehyde condensing of aromatic amine fragment have low fluorescence quantum yield and fluorescence lifetime, and their two-photon absorption cross section is also relatively small. But it can occur highly efficient ESIPT induced by two-photon inadiation.