Probing the Electronic Properties and Interaction Landscapes in a Series of N-(Chlorophenyl)pyridinecarboxamides

Abstract

A 3 × 3 isomer grid of nine N -(chlorophenyl)pyridinecarboxamides ( NxxCl ) is reported with physicochemical studies and single crystal structures ( Nx = pyridinoyl moiety; xCl = aminochlorobenzene ring; x = para -/ meta -/ ortho -), as synthesized by the reaction of the substituted p -/ m -/ o -pyridinecarbonyl chlorides ( Nx ) with p -/ m -/ o -aminochlorobenzenes ( xCl ). Several of the nine NxxCl crystal structures display structural similarities with their halogenated NxxX and methylated NxxM relatives ( x = p -/ m- / o -substitutions; X = F, Br; M = methyl). Indeed, five of the nine NxxCl crystal structures are isomorphous with their NxxBr analogues as the NpmCl / Br , NpoCl / Br , NmoCl / NmoBr , NopCl / Br , and NooCl / Br pairs. In the NxxCl series, the favored hydrogen bonding mode is aggregation by N–H···N pyridine interactions, though amide···amide intermolecular interactions are noted in NpoCl and NmoCl . For the NoxCl triad, intramolecular N–H···N pyridine interactions influence molecular planarity, whereas NppCl·H 2 O (as a monohydrate) exhibits O–H···O, N–H···O1W, and O1W-H···N interactions as the primary hydrogen bonding. Analysis of chlorine-containing compounds on the CSD is noted for comparisons. The interaction environments are probed using Hirshfeld surface analysis and contact enrichment studies. The melting temperatures ( T m ) depend on both the lattice energy and molecular symmetry (Carnelley’s rule), and the melting points can be well predicted from a linear regression of the two variables. The relationships of the T m values with the total energy, the electrostatic component, and the strongest hydrogen bond components have been analyzed.

Roles of Hydrogen, Halogen Bonding and Aromatic Stacking in a Series of Isophthalamides

“…amide interaction is less notable (N c values ≥ 0.90). In tandem, the R In previous studies of 3 × 3 isomer grids, we reported detailed analyses of their melting points and examined the influence of the substituent position and molecular symmetry [17][18][19]40]. The X-DIP series with six compounds shows a melting point trend increasing along the series from H→F→Cl→Br→I→NO 2 , noting Z' = 3 for Cl-DIP and hemihydrate in I-DIP• 1 /2(H 2 O).…”

Crystal structure and characterization of monascin from the extracts of Monascus purpureus-fermented rice

“…Given the high similarity in electron-density properties (Gallagher et al, 2022) between a compound interacting with the active site of a protein in the biological environment and its crystalline state (Zhurova et al, 2009), an electron-density study was initiated on monascin in its crystalline state to explore its molecular structure (Shyni et al, 2021). Experimental electron-density studies of monascin are conducted by utilizing atomic parameters from the Experimental Library of Multipolar Atom Model 2 (ELMAM2) database (Bibila Mayaya Bisseyou et al, 2012), which is based on optimal local coordinate systems (Domagała & Jelsch, 2008), due to the absence of high-resolution diffraction data.…”