Synthesis And Properties Of New Unsymmetrical Diarylethenes Bearing An Azaindole Moiety

Photochromic diarylethenes are the most potential materials among all the reported photochromic compounds, due to their potential applications, remarkable fatigue resistance, and good thermal stability of both two isomers. Azaindole can be considered as a bioisostere of an indole and purine moiety. In recent years, numerous compounds containing azaindole has been designed as coordination agents and biological molecules because of its special electronic structure. In addition, azaindole derivatives have demonstrated their potential in controlling the activity of many enzymes, antineoplastic and antibacterial.In this dissertation, a total of 13 new diarylethenes were designed and synthesized, which mainly focused on the diarylethene photochromism, fluorescent molecules switches, optical memories, multiple responses and electrochemical properties. The contents were concluded as follows:1. In the research the introduction and development of the diarylethenes were reviewed. And then, our research subject was brought out on the survery of the current focus.2. A new class of photochromic diarylethenes with both azaindole and thiophene moieties were firstly synthesized to investigate the effects of the substituents on their photochromic behaviors, and their structures were determined by single crystal X-ray diffraction analysis. The electron-donating substituents significantly enhanced their cyclization quantum yields, while the electron-withdrawing groups greatly increased the molar absorption coefficient of their closed-ring isomers. Cyclic voltammetry studies indicated that the band-gaps of diarylethenes with an azaindole notably increased when going from electron-donating substituents to electron-withdrawing substituents.3. Four asymmetrical diarylethenes containing an azaindole moiety and a variable heteroary rings with thiazyl, thienyl, pyrrolyl and pyridine moiety have been synthesized. Compared to the diarylethenes with a higher aromatic stabilization energy aryl ring (DT-8 and DT-9), the diarylethenes with a lower aromatic stabilization energy aryl ring (DT-6 and DT-7) exhibited better thermal stability.4. Four photochromic diarylethenes with both azaindole and benzene moieties were synthesized. The differences of the diarylethenes lie in the groups linked on the active carbon position of the benzene moiety. The photochromic and electrochemical properties of these diarylethenes with different substituents were studied in detial. The diarylethenes showed poorer photochromism, fatigue resistance, and thermal stability with the intruduction of hexatomic ring. Moreover, the electrochemical results indicated that the oxidation process for the open-ring isomers occurred at higher potentials than in the corresponding closed-ring isomers.