AUTHOR=Ullah Zakir , Kim Kang , Venkanna Arramshetti , Kim Hye su , Kim Moon Il , Kim Mi-hyun 

TITLE=Plausible Pnicogen Bonding of epi-Cinchonidine as a Chiral Scaffold in Catalysis

JOURNAL=Frontiers in Chemistry

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2021.669515

DOI=10.3389/fchem.2021.669515

ISSN=2296-2646

ABSTRACT=<p>As a non-covalent interaction of a chiral scaffold in catalysis, pnicogen bonding of <italic>epi-</italic>cinchonidine (<italic>epi-CD</italic>), a cinchona alkaloid, was simulated to consider whether the interaction can have the potential controlling enantiotopic face like hydrogen bonding. Among five reactive functional groups in <italic>epi-CD</italic>, two stable complexes of the hydroxyl group (X-epi-CD1) at C<sub>17</sub> and of the quinoline ring (X-epi-CD2) at N<sub>16</sub> with pnictide family analytes [X = substituted phosphine (PX), i.e., F, Br, Cl, CF<sub>3</sub>, CN, HO, NO<sub>2</sub>, and CH<sub>3</sub>, and pnictide family analytes, i.e., PBr<sub>3</sub>, BiI<sub>3</sub>, SbI<sub>3</sub>, and AsI<sub>3</sub>] were predicted with intermolecular interaction energies, charge transfer (Q<sub>Mulliken</sub> and Q<sub>NBO</sub>), and band gap energies of HOMO–LUMO (Eg) at the B3LYP/6-31G(d,p) level of density functional theory. It was found that the dominant site of pnicogen bonding in epi-CD is the quinoline ring (N<sub>16</sub> atom) rather than the hydroxyl group (O<sub>36</sub> atom). In addition, the UV-Vis spectra of the complex were calculated by time-dependent density functional theory (TD-DFT) at the B3LYP/6-31+G(d,p) level and compared with experimental measurements. Through these calculations, two intermolecular interactions (H-bond vs. pnicogen bond) of <italic>epi-CD</italic> were compared.</p>