Unconventional hydrogen bonding and π-stacking in two substituted pyridine carboxamides

Abstract

The crystal structures of two para-substituted aryl derivatives of pyridine-2-carboxamide, namely N-(4-fluorophenyl)pyridine-2-carboxamide, C(12)H(9)FN(2)O, (I), and N-(4-nitrophenyl)pyridine-2-carboxamide, C(12)H(9)N(3)O(3), (II), have been studied. Compound (I) exhibits unconventional aryl-carbonyl C-H...O and pyridine-fluorine C-H...F hydrogen bonding in two dimensions and well defined π-stacking involving pyridine rings in the third dimension. The conformation of (II) is more nearly planar than that of (I) and the intermolecular interactions comprise one-dimensional aryl-carbonyl C-H...O hydrogen bonds leading to a stepped or staircase-like progression of loosely π-stacked molecules. The close-packed layers of planar π-stacked molecules are related by inversion symmetry. Two alternating interplanar separations of 3.439 (1) and 3.476 (1) Å are observed in the crystal lattice and are consistent with a repetitive packing sequence, ABA'B'AB…, for the π-stacked inversion pairs of (II).

Structures and conformational analysis of a 3 × 3 isomer grid of nine N-(fluorophenyl)pyridinecarboxamides

“…The related compound with CSD code, GEPQIC, 38 is the parent chloro derivative [NopCl] and is isomorphous with WUVYIV 39 (Br derivative as NopBr) but not with NopF. 23 The molecular overlay between the Cl/Br analogues [GEPQIC/WUVYIV] is within 0.005 A and the C 6 / C 5 N interplanar rings are also close to 0 .…”

“…15 The NmxF triad has been studied in an unusual synthesis of nicotinamides 21 and recently NmoF has been cited as a promising candidate for lead design as a selective inhibitor of LmSir2, a sirtuin protein from Leishmania, and therefore, a potential new drug and/or scaffold for leishmaniasis drug design. 16 In the NoxF series, NopF has been incorporated as a deprotonated ligand into a Co III complex 22 (NopF crystal structure reported recently 23 ) and NomF as an intermediate in the synthesis of thioamide analogues (mp 65-82 C 24 vs. 77.2-78.0 C); NooF has been employed as a ligand in a ruthenium complex developed as a potential cytotoxic agent. 17 Overall, modest spectroscopic data are available for several of the NxxF isomers from these diverse reports.…”

“…17 Overall, modest spectroscopic data are available for several of the NxxF isomers from these diverse reports. [15][16][17][21][22][23][24] 2 Experimental section…”

Gold(III) Complexes of Pyridyl- and Isoquinolylamido Ligands: Structural, Spectroscopic, and Biological Studies of a New Class of Dual Topoisomerase I and II Inhibitors

“…Single-crystal X-ray structures were determined for H 2 L 4 and the gold(III) complexes 1 – 4 . The ligands H 2 L 1 , H 2 L 2 , and HL 3 have been described previously in the literature. − Density functional theory (DFT) simulations have been used to delineate the electronic structures of 1 – 4 . The cytotoxicity profiles of compounds 2 – 4 were evaluated by the National Cancer Institute (NCI) using their panel of 60 human cancer cell lines.…”

Microwave-Assisted Synthesis of New Substituted Anilides of Quinaldic Acid

“…The total structure of 5c can be described as a slightly screwed boat with no intermolecular hydrogen bonding. The intramolecular N1-H1···N2 contact is present along with another short contacts forming the 3D structure ( Figure 2 ), instead of a stairs-like supramolecular architecture typical for previously reported members of the families of N -(4-halophenyl)quinoline-2-carboxamides [ 31 ] or N -(4-halophenyl)pyridine-2-carboxamides [ 32 , 33 , 34 , 35 ].…”