Ab initio insights on photophysics of 9-methylhypoxanthine. (17th June 2016)

• Record Type: Journal Article
• Authors: Guo, Xugeng; Yuan, Huijuan; Zhu, Qiuling; An, Beibei; Zhang, Jinglai
• Is Part Of: Molecular physics. Volume 114:Number 12(2016)
• Page Start: 1907
• Page End: 1914
• Publication Date: 2016-06-17
• Subjects: Ab initio calculations -- conical intersection -- internal conversion -- excited state -- photophysics; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2016.1164348
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: In this work, the low-lying electronic singlet states of 9-methylhypoxanthine (9MHPX) were explored by the complete active space self-consistent-field (CASSCF) and complete active space second-order perturbation theory (CASPT2) calculations, and the conical intersections between the optically bright excited S1 state and ground S0 state were optimised by the two-root state-averaged SA-2-CASSCF approach. These studies indicate that four slightly different kinds of S1 /S0 conical intersections are identified computationally for 9MHPX, corresponding to four main internal conversion pathways, respectively, all of which are found to show the comparable timescales according to dynamics simulations. At the CASPT2 level, four bright ππ * transitions of 9MHPX are calculated to locate at 4.47, 5.35, 5.97 and 6.30 eV, respectively, responsible for the available experimental absorption peaks of 9MHPX in the vapour phase (4.41, 5.19, 6.05 and 6.42 eV). Though one relatively weak ππ * transition computed at 5.69 eV is not observed in the vapour phase, it is in accordance with the circular dichroism measurement of another hypoxanthine derivative deoxyinosine 5'-phosphate near 5.51 eV. Abstract :