Unraveling the Conformational and Electronic Landscape of 3-Pyridinecarboxaldehyde: A Spectroscopic Journey through Conformer-Specific Ionization
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide 3-Pyridinecarboxaldehyde (3-PCA) is a versatile building block, but its conformational and ionization behavior remains underexplored. Using high-resolution IR-resonant vacuum ultraviolet mass-analyzed threshold ionization spectroscopy and Franck–Condon simulations, two conformers, s- cis and s- trans, were identified in the gas phase, distinguished by adiabatic ionization energies of 76 123 ± 4 and 76 173 ± 4 cm –1, respectively, and revealing conformer-specific structural dynamics and frontier orbital changes during ionization. Computational analyses, including anharmonic and natural bond orbital studies, provided structural and electronic insights. Analysis of jet-cooled conformer populations indicated an S 0 -state energy difference of 40 ± 14 cm –1, while in the D 0 state, the two conformers are essentially near-isoenergetic within experimental uncertainty (≈ −10 ± 14 cm –1 ). These results highlight the delicate balance of cationic conformer stability and its distinct ionization behavior. This work provides conformer-specific spectroscopic and theoretical benchmarks for understanding ionization-induced structural and stereoelectronic effects in formyl-substituted pyridines with implications for their reactivity and excited-state dynamics.
Source: ACS Physical Chemistry Au
Authors: Sung Man Park, Hyojung Kim, Chan Ho Kwon
Institutions: Kangwon National University, Institute for Molecular Science
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,500
Awards: G1878966886, G8235085587
OpenAlex ID: W4415092256