TY - JOUR

T1 - para-substituted pyridines: Effects on the interaction with 2-perfluoropropyl iodide and vibrations

AU - Benassi, Enrico

AU - Nurtay, Lazzat

AU - Fan, Haiyan

N1 - HF thanks Nazarbayev University small grant 110119FD4542 and 11022021FD2928. Computational resources were kindly provided by Shabyt HPC at Nazarbayev University.

PY - 2023/3/5

Y1 - 2023/3/5

N2 - Vibrational spectroscopy and quantum chemical calculations were employed to investigate the impact of electron donating and electron withdrawing para-substituents on pyridine in terms of molecular and electronic structure, electrostatic properties and the seven in-plane, ring-related vibrational normal modes (RNMs), along with the capability of pyridinyl nitrogen atom to get involved in halogen bonding (XB) with 2-perfluoropropyl iodide (iso-C3F7I). A descriptor was proposed to quantitatively describe pyridine's para-substituents’ electron donating/withdrawing ability. Some quantitative correlations were then identified for the geometric and topological characteristics on bond critical points of XB complexes, the frequency shifts of some RNMs upon XB and thermodynamic quantities of XB formation versus the aforementioned substitution descriptors. Natural bond orbital (NBO) analysis established the formation of XB is beyond a mere electrostatic interaction. Such a XB occurring between the electron lone pair of pyridinyl N and I on iso-C3F7I indicated a strong charge transfer (CT) character. The comparison between the FT-IR/ Raman spectra of 6 binary systems and the calculated spectra for monomers and XB dimer revealed the potential halogen bond between the substituents and iso-C3F7I as well as the intermolecular hydrogen bond (HB) between two same molecules of some substituted pyridines.

AB - Vibrational spectroscopy and quantum chemical calculations were employed to investigate the impact of electron donating and electron withdrawing para-substituents on pyridine in terms of molecular and electronic structure, electrostatic properties and the seven in-plane, ring-related vibrational normal modes (RNMs), along with the capability of pyridinyl nitrogen atom to get involved in halogen bonding (XB) with 2-perfluoropropyl iodide (iso-C3F7I). A descriptor was proposed to quantitatively describe pyridine's para-substituents’ electron donating/withdrawing ability. Some quantitative correlations were then identified for the geometric and topological characteristics on bond critical points of XB complexes, the frequency shifts of some RNMs upon XB and thermodynamic quantities of XB formation versus the aforementioned substitution descriptors. Natural bond orbital (NBO) analysis established the formation of XB is beyond a mere electrostatic interaction. Such a XB occurring between the electron lone pair of pyridinyl N and I on iso-C3F7I indicated a strong charge transfer (CT) character. The comparison between the FT-IR/ Raman spectra of 6 binary systems and the calculated spectra for monomers and XB dimer revealed the potential halogen bond between the substituents and iso-C3F7I as well as the intermolecular hydrogen bond (HB) between two same molecules of some substituted pyridines.

KW - Charge transfer

KW - Electron donating/withdrawing groups

KW - Halogen bond

KW - Vibrational spectroscopies

KW - para-substitution effects

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85147404775&origin=inward&txGid=d2dab2fb26ba06e8c6d548d55cb7d4e7

UR - https://www.mendeley.com/catalogue/6952e372-8ade-39ef-a0b0-4c3ad31d81b1/

U2 - 10.1016/j.molstruc.2022.134632

DO - 10.1016/j.molstruc.2022.134632

M3 - Article

VL - 1275

JO - Journal of Molecular Structure

JF - Journal of Molecular Structure

SN - 0022-2860

M1 - 134632

ER -