Thioamide spectroscopy: long path length absorption and quantum chemical studies of thioformamide vapour, CHSNH₂/CHSND₂

Abstract

The 270 nm absorption spectra of thioformamide, CHSNH2 and CHSND2, have been photographically recorded under conditions of long path length (88 m) and moderate resolution (7.5 Å/mm). The absorption was assigned to the electron promotion, nS → π* (CS), and to the electronic transition, [Formula: see text]. The spectra proved to be complex, highly congested and somewhat diffuse which limited the extent of the vibrational assignments. Progressions in five members were observed in both CHSNH2/CHSND2 in intervals of 516/496 cm−1 which were assigned to ν10, the out-of-plane aldehyde wagging mode. It was concluded on Franck–Condon grounds that the [Formula: see text] molecule was non-planar at the aldehyde center. Structures and vibrational frequencies were calculated for the [Formula: see text] and the[Formula: see text] electronic states at the 3-21G* SCF level. The calculations confirmed that the lower state was strictly planar and predicted that both the aldehyde and amino groups were pyramidal in the upper electronic state.

Uncovering the unexplored diversity of thioamidated ribosomal peptides in Actinobacteria using the RiPPER genome mining tool

“…This analysis showed that thiovarsolins A and B are N -acetylated APR tripeptides in which the amide bond between Pro and Arg is substituted by a thioamide (δ C = 200 ppm) (Figure 5D). This was supported by accurate mass data (Supplementary Table S5) and an absorbance maximum at ∼270 nm for both molecules, which is characteristic of a thioamide group (61). Additionally, a trans double bond is present between Cβ and Cγ of the arginine side chain in thiovarsolin A.…”

Characterization of the Simplest Thiolimine: The Higher Energy Tautomer of Thioformamide

“…Owing to its quick decomposition at ambient conditions (see Supporting Information) reports on experimental data of 1 are rare [27, 28] . Only two infrared studies on 1 in the liquid and solid phases exist, which provide IR spectra in good agreement with each other, but are controversial in the assignment of the observed bands [29, 30] .…”

Uncovering the unexplored diversity of thioamidated ribosomal peptides in Actinobacteria using the RiPPER genome mining tool

“…This was supported by accurate mass data (Table S5) and an absorbance maximum at ~270 nm for both molecules, which is characteristic of a thioamide group. 52 Figure S35) in which the Ala residue in each repeat was substituted by Gly. This was expressed in M1146 TARvar ΔvarA using a pGP9based expression plasmid.…”