Computer‐Aided Design of Fluorinated Flavin Derivatives by Modulation of Intersystem Crossing and Fluorescence. Issue 7 (27th April 2022)

• Record Type: Journal Article
• Authors: Bracker, Mario; Kubitz, Mira K.; Czekelius, Constantin; Marian, Christel M.; Kleinschmidt, Martin
• Is Part Of: ChemPhotoChem. Volume 6:Issue 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-27
• Subjects: ab initio calculations -- computational photochemistry -- excited states -- fluorine -- quantum chemistry; Photochemistry -- Periodicals; Periodicals; Electronic journals; 541.35
• DOI: 10.1002/cptc.202200040
• Languages: English
• ISSNs: 2367-0932

Abstract

Abstract: This study aims at finding fluorinated flavin derivatives with modified intersystem crossing (ISC) and fluorescence properties. In total, photophysical properties of 8 derivatives were investigated computationally using combined density functional theory and multireference configuration interaction methods. On top of a screening procedure, the excited‐state decay mechanisms of selected chromophores were investigated in detail. Kinetic schemes including fluorescence, ISC as well as internal conversion (IC) channels were set up to unravel the complex excited‐state decay kinetics. We find two chromophores that exhibit promising properties with respect to fluorescence microscopy. Distinctive stabilization of the bright S 1 ππ * state results in absorption in the green wavelength region and emission of (infra‐)red light. The 1 ( πH πL )⤳ 3 ( π H–1 πL ) ISC channel of the flavin chromophore was found to be deactivated upon both modifications, but nonradiative deactivation of the fluorescence by IC appears to be a problem. Alternative modifications of the pteridine dione moiety were found to result in a marked stabilization of nπ * states along with activation of El‐Sayed allowed ISC channels. For the latter two compounds, we predict fluorescence to be quenched by ISC followed by efficient population of the long‐lived T 1 state via IC. Abstract : Excited states : In this study, fluorinated flavin derivatives with modified intersystem crossing (ISC) and fluorescence properties are designed and analysed by means of high‐level quantum chemical methods. In total, photophysical properties of eight derivatives are investigated. Compounds with promising energetics are examined further with respect to excited‐state decay mechanisms. Kinetic schemes of four selected fluorinated flavin derivatives including ISC, fluorescence as well as internal conversion channels are presented.