Naphthacenequinone Photochromic Mechanism And Bithiazole Sensitization Theory Of Solvent

Photochromic materials have wide applications in many fields such as optical storage materials, optical devices, and light-operated switch, ect. Among various photochromic materials, naphthacenequinones is one of the most promising materials because of their unique properties such as fatigue resistance and thermal stability. In this paper, the research are focused on 6-hydroxy-5,12-naphthacenequinone derivatives, involve their isomers and transition state structures in photochromic reaction, as well as the relationship between their structure and photochromic properties. This research can provide a theoretical basis to further design of highly efficient quinone photochromic materials.This paper mainly includes the following sections1. Photoisomerizations of 6-hydroxy-5,12-naphthacenequinone and its derivatives bearing methyl and phenyl group were theoretically investigated with density functional theory method and ab initio CIS method at the B3LYP 6-31G basis set, respectively. The obtained potential energy curves disclosed that a four-state cycle existed in the ground and excited states. It was also found that the activation energy for the methyl transfer was higher compared to the phenyl transfer, which was consistent to the experimental results that the photoisomerization of the phenyl substituted derivative was more rapid than the methyl substituted derivatives. Further hybrid time dependent density functional theory (TD-DFT) was used to investigate the abso rption and fluorescence spectra of these compounds under solvent effect condition. The calculated values were in agreement with the experimental results and excitation condition of photochromic reactions.2. The molecular structure of the compounds has an important effect on its performance of photochromic. In order to investigate the influence of conjugate substituents on the subject and conjugated degree of the parent quinone ring o n the performance of photochromic, the different conjugate substituents and 6-hydroxy-5,12-naphthacenequinone derivatives of different parent quinone ring conjugated are theoretical studied.3.The cis-trans isomers of 2,2'-dimethyl-4,4'-bithiazole,1:1 hydrogen-bond complex (Ⅰ) between trants-2,2'-dimethyl-4,4'-bithiazole and chloroform, and hydrogen-bond complex (Ⅱ) between cis-2,2'-dimethyl-4,4'-bithiazole and chloroform were calculation studied by using ab initio calculation at MP2/6-31 G(d,p)basis set level. The results showed that in the gas phase, trans-2,2'-dimethyl-4,4'-bithiazole was more stable than cis-2,2'-dimethyl-4,4'-bithiazole. There are strong hydrogen-bonds existing in the 1:1 hydrogen-bond complexes, as interaction between the lone pair electrons on the N atom andσ*(C-H) antibonding orbitals in chloroform molecule, as well as weak interaction between C-H and Cl. The existing hydrogen-bonds made cis-2,2'-dimethyl-4,4'-bithiazole more stable in chloroform solvent. Hydrogen-bond and effect of ring current predicted in this theoretical work successfully explain the NMR experimental results.