Synthesis And Function Of Photochromic Naphthopyran Fluorescent Switches

Naphthopyrans, which are an important class of photochromic dyes, attract much attention because of their advantages, such as fast light-response, high storage density and fatigue resistance, etc. The photochromic naphthopyrans can modulate "ON/OFF" of the fluorescent, when the fluorophore grafted into naphthopyran to prepare photochromic fluorescent switch. In this dissertation, three photochromic naphthopyran fluorescent switches were synthesized and the optical properties were researched. The main contents of this dissertation are as following:1. The naphthalimide derivative and three photochromic fluorescent compounds based on naphthopyrans and benzimidazole were fabricated. The structures of the compounds were verified by NMR and mass spectrometry.2. The photochromic performance, fluorescence photoswitch properties and the mechanism of the compounds were characterized by UV-Vis spectra and the fluorescence spectra in THF solution. The results reveal that the fluorescent intensity can be tuned reversibly by alternative irradiation with ultraviolet and visible light with the changes of naphthopyran. The photoinduced energy transfer from excited benzimidazole to naphthopyran was responsible for the fluorescent quenching. The quenched extents of their emission are related to space between photochromic naphthopyran and benzimidazole. The shorter the space, the larger the quenched extent. At last, the fluorescence photoswitch properties of solution blending of photochromic fluorescent compounds and naphthalimide (NBNI) in different ratios were investigated, respectively. The results show that the fluorescent intensity of PBI of photochromic fluorescent compounds can be modulated by changing the relative content of photochromic fluorescent compounds and naphthalimide (NBNI).