Beyond the Vibrational Stark Effect: Unraveling the Large Redshifts of Alkyne C-H Bond in Solvation Environments.

ABSTRACT: C-H···O hydrogen bonds are formed in systems ranging from biomolecular complexes to small-molecule structures. Previous work has focused on the blueshifts in the C-H stretching frequency (ν¯CH) induced by these hydrogen bonds and their chemical and biological roles. Here, we show that, in contrast, terminal alkyne C-H hydrogen bonds exhibit large redshifts (50-100 cm^-1) upon hydrogen bonding with oxygen-containing solvents. Using spectroscopic and computational approaches, we elucidate and compare the roles of the vibrational Stark effect, bond polarization, and charge transfer in driving the C-H redshift. We show that the redshifts of alkyne's terminal C-H upon the formation of hydrogen bonds correlate with the Lewis basicity of the solvent and are significantly larger than tho

SUBMITTER: Zheng C 

PROVIDER: S-EPMC12085902 | biostudies-literature | 2025 Feb

REPOSITORIES: biostudies-literature