Study Of Excited-state Proton Transfer In2-naphthol Schiff Base Derivatives

It is well known that excited state intramolecular proton transfer is one of very basic processes in the nature. When the organic molecules are excited by ray, electricity and heat, they absorb energy and transit from the ground state to the excited state. There is a ESIPT process between intramolecular detur proton groups and acceptive proton groups (for example:N, O, S etc.). It is an obvious feature that the detur groups always take place tautomerism in this process, such as in the excited state enol form transfers to keto form, and result in red-shift of the emission wavelength of molecules. The organic molecules which possess ESIPT property usually have the characters of optical nonlinearity, optical bistability, photochromic, fast response, reversible reaction process. So these organic molecules are often applied for photochromic material, waveguide, optical limiting, and fluorescent probe.With the development of the optical technology, more and more scientists try to explore the optical material with good performance. Because of the easy way of the synthesis and being modified, and the cheap raw material, Schiff bases attract increasing number of attention. Many research teams have deeply studied the properties of Schiff base for several years. The results show that Schiff bases do not only have features of anticancer, antibacterial, antiviral, regulation of plant growth and development, and inhibition of superoxide anion radical in the field of biology, but also have good characteristics of metal complexation and ion extraction in analytical chemistry. Apart from the above, Schiff bases perform special usefulness in fluorescent probes. The Schiff bases and its derivatives which own conjugated system bring a profound and lasting impact in the field of spectroscopy, stereochemistry, electrochemistry, analytical chemistry, molecular self-assembly, biomimetic systems, supramolecular chemistry.In summary, we chose the Schiff bases which had2-hydroxy-naphthaldehyde as the basic unit for our object of study. And the property of optics of the Schiff bases were studied by fluorescence emission spectra, ultraviolet absorption spectra, fluorescence quantum yield, fluorescence lifetime and other means. In addition, we investigated the influence of pH for the spectrums of these Schiff bases.