Substituent Effects on the Vibrational Properties of the CN Stretch Mode of Aromatic Nitriles: IR Probes Useful for Time-resolved IR Spectroscopy

Suin Choi, Junyoung Park, Kyungwon Kwak, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Developing ideal IR probes is essential to understand the structure and dynamics of biomolecules with time-resolved IR spectroscopies and imaging techniques. Especially, nitrile (CN) group has recently been proposed to serve as IR probes of the local environment of proteins. Herein, we investigated the effect of a substituent on the vibrational properties of the benzonitrile. The electron-donating and withdrawing character of p-substituent on benzonitrile are expected to modulate the vibrational frequency, molar extinction coefficient, and vibrational lifetime of CN probe. FT-IR revealed the positive correlation between electron-donating character and the molar extinction coefficient of CN stretch mode. Infrared pump-probe (IR-PP) measurements showed that the vibrational lifetime of CN stretch mode exhibits a relatively weak correlation with the electron-donating strength. Among the investigated samples, 4-dimethylamino benzonitrile with the strongest electron-donating strength shows enhanced absorption and extended vibrational lifetime. Utilizing substituent effects will be a practical strategy to improve the performance of the IR probe.

Original languageEnglish
Pages (from-to)2626-2632
Number of pages7
JournalChemistry - An Asian Journal
Volume16
Issue number18
DOIs
Publication statusPublished - 2021 Sep 20

Keywords

  • Electron-donating effect
  • IR probes
  • Nitrile
  • Peptides and proteins
  • Time-resolved IR spectroscopy

ASJC Scopus subject areas

  • Biochemistry
  • Organic Chemistry

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