Multireference theoretical studies on the solvent effect of firefly multicolor bioluminescence

• Published in: International journal of quantum chemistry 2011-11, Vol.111 (13), p.3371-3377
• Main Authors: Chen, Shu-Feng, Yue, Ling, Liu, Ya-Jun, Lindh, Roland
• Format: Article
• Language: English
• Subjects: Chemistry; firefly bioluminescence; Kemi; multireference calculation; NATURAL SCIENCES; NATURVETENSKAP; solvent effect
• ISSN: 0020-7608; 1097-461X; 1097-461X
• DOI: 10.1002/qua.22966

In concert with the recent spectroscopic studies of the light‐color modulation mechanism of firefly (Hirano et al., J Am Chem Soc 2009, 131, 2385), quantum chemical calculations using complete active space SCF (CASSCF), multistate complete active space second order perturbation (MS‐CASPT2) theory as well as a time‐dependent density functional theory (TD‐DFT) approach with the Coulomb attenuated hybrid exchange‐correlation functional (CAM‐B3LYP) were performed on the excited state (S1) of the keto‐form oxyluciferin (keto‐OxyLH2). Benzene, DMSO, CH3CN, and H2O were chosen as polar solvents. The polarization effect of less polar solvent was considered by a simple model, complex of keto‐OxyLH2, and NH3 with different covalent character. The calculated results supported the experimental conclusion: (1) the light emitter of bioluminescence is the S1 state of keto‐OxyLH2 anion [(keto‐1)*], and (2) light emission from (keto‐1)* is modulated by the polarity of surrounding environment and the degree of covalent character of hydrogen bond between (keto‐1)* and a protonated basic moiety. The mechanism of the multicolor bioluminescence was discussed from the theoretical viewpoint. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 111:3371–3377, 2010