Bhowmik Suman, Dutta Abhijit, Sen Pratik
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, Uttar Pradesh, India.
J Phys Chem A. 2024 Aug 22;128(33):6864-6878. doi: 10.1021/acs.jpca.4c03224. Epub 2024 Aug 11.
Understanding the intricate factors governing intersystem crossing (ISC) in aromatic carbonyl compounds remains a long-standing interest among researchers. This study unveils the crucial roles of vibration in influencing the ISC of a typical aromatic carbonyl chromophore, benzanthrone, and how hydrogen bonding and solvent viscosity affect these vibrations and, thus, the associated ISC kinetics. We demonstrate that for benzanthrone, the ISC is exceedingly facile in an aprotic solvent, while in protic solvents, the ISC is significantly suppressed through the formation of the hydrogen-bonded state. Moreover, in a high-viscosity medium, ISC is further retarded due to restrictions of volume-changing motions, which may assist ISC. Theoretical calculations revealed that the C═O bond vibration and specific out-of-plane vibrations accompanying a volume change could be the probable coordinates for ISC. These findings provide valuable insights for tailoring the excited-state behavior of carbonyl-functionalized materials for diverse applications in photocatalysis, organic electronics, and biomedicine.
了解控制芳香族羰基化合物系间窜越（ISC）的复杂因素一直是研究人员长期关注的问题。本研究揭示了振动在影响典型芳香族羰基发色团苯并蒽酮的ISC过程中的关键作用，以及氢键和溶剂粘度如何影响这些振动，进而影响相关的ISC动力学。我们证明，对于苯并蒽酮，ISC在非质子溶剂中非常容易发生，而在质子溶剂中，ISC通过形成氢键状态而显著受到抑制。此外，在高粘度介质中，由于体积变化运动受到限制，ISC进一步受阻，而这种运动可能有助于ISC。理论计算表明，C═O键振动和伴随体积变化的特定面外振动可能是ISC的可能坐标。这些发现为定制羰基功能化材料的激发态行为提供了有价值的见解，可用于光催化、有机电子学和生物医学等多种应用。
