Photoenhancement of the C≡N Stretching Vibration Intensity of Aromatic Nitriles

• DOI: 10.1021/acs.jpclett.2c02418
• Publication Date: 2022-10-12T13:48:47Z
• Authors: Jingsong Liu; Ran-ran Feng; Liang Zhou; Feng Gai; Wenkai Zhang
• Keywords: Photoexcitation; Vibrational energy relaxation; Molar absorptivity

The C≡N stretching vibration is a versatile infrared (IR) reporter that useful for wide range of applications. Aiming to further expand its spectroscopic utility, herein, we show that, using 4-cyanoindole and 4-cyano-7-azaindole as examples, photoexcitation can significantly shift the frequency (νCN) enhance molar extinction coefficient (εCN) this vibrational mode aromatic nitriles these indole derivatives, enhancement factor reach 13. Moreover, find while solvent relaxation at excited electronic state(s) always leads an increase in εCN, effect on νCN depends solute solvent. Taken together, results demonstrate differently affect local environment nitrile group conjugation with ring and, more importantly, serve sensitive IR probe charge electron transfer processes which involved.