title: Direct Spectroscopic Evidence for an n→π* Interaction.
abstract: The n→π* interaction is an extremely weak but very important noncovalent interaction. Although this interaction is widely present in biomolecules and materials, its existence is counterintuitive and so has been debated extensively. Herein, we have reported direct spectroscopic evidence for an n→π* interaction for the first time by probing the carbonyl stretching frequency in phenyl formate using isolated gas-phase IR spectroscopy. This result also demonstrates that the conformational preference for the cis conformer of phenyl formate compared to the trans conformer arises due to the presence of the n→π* interaction in the former. The direct proof reported herein for this controversial but important noncovalent interaction should stimulate further experimental and theoretical investigation on this intriguing research topic.
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune-, 411008, Maharashtra, India.
authors.forename: Santosh K
authors.initials: SK
authors.lastname: Singh
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune-, 411008, Maharashtra, India.
authors.forename: Kamal K
authors.initials: KK
authors.lastname: Mishra
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune-, 411008, Maharashtra, India.
authors.forename: Neha
authors.initials: N
authors.lastname: Sharma
authors.affiliation: Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune-, 411008, Maharashtra, India. a.das@iiserpune.ac.in.
authors.forename: Aloke
authors.initials: A
authors.lastname: Das
keywords: conformational analysis; electronic spectroscopy; gas-phase IR spectroscopy; supersonic jet