Inconsistent hydrogen bond-mediated vibrational coupling of amide I

Using infrared spectroscopy and density functional theory (DFT) calculations, we scrutinized an amide (dimethylformamide) as a model compound to interpret the interactions of amide 1 with different phenol derivatives (para-chlorophenol (PCP) and para-cresol (CP)) as model guest molecules . We established the involvement of amide I in vibrational coupling with symmetric and asymmetric CC modes of different phenolic derivatives and how their coupling was dependent upon different guest aromatic phenolic compounds. Interestingly, substitution of phenol perturbed the pattern of vibrational coupling with amide I. The symmetric and asymmetric CC modes of PC were coupled significantly with amide 1. For PCP, the symmetric CC mode coupled significantly, but the asymmetric mode coupled negligibly, with amide I. Here, we reveal the nature of vibrational coupling based on the structure of a guest molecule hydrogen-bonded with amide I. Our conclusions could be valuable for depiction of the unusual dynamics of coupled amide-I modes as well as the dependency of vibrational coupling on altered factors.

Automated summary

Using infrared spectroscopy and density functional theory (DFT) calculations, we investigated the interactions between amide 1 and phenol derivatives (para-chlorophenol (PCP) and para-cresol (CP)). We found that amide I was involved in vibrational coupling with symmetric and asymmetric CC modes of different phenolic derivatives, and this coupling varied with different guest aromatic phenolic compounds. Substituting phenol affected the pattern of vibrational coupling with amide I. The symmetric and asymmetric CC modes of PC were significantly coupled with amide 1, while for PCP, the symmetric CC mode had significant coupling but the asymmetric mode had negligible coupling with amide I. Our findings provide valuable insights into the nature of vibrational coupling and its dependency on different factors.