Hydrogen Bond Patterns of Dipyridone and Bis(Hydroxypyridinium) Cations

Abstract

Dipyridonyl-substituted derivatives 2–4 of benzene, pyridine, and pyrazine, respectively, were synthesized to examine the ability of 2-pyridone and its protonated species to direct the self-assembly by hydrogen bonding. Structural analysis by single-crystal X-ray diffraction (SCXRD) of 2 and 4 in trifluoroacetic acid demonstrated that salts are formed as a result of the transfer of protons from the acid to the base (organic species) to generate a bis(hydroxypyridinium) dication. However, if no proton transfer takes place like in the case of crystals of 3 grown from DMSO/H 2 O, the self-assembly is mainly directed by the typical R 2 2 (8) hydrogen bond motif of 2-pyridone. These results indicate that the process of converting a neutral 2-pyridonyl group into a hydroxypyridinium cation makes structure prediction difficult. Consequently, examination of proton transfer and assembly of dipyridone and its protonated species are of interest. In combination with SCXRD, Hirshfeld surface analysis (HSA) was also used to have a better understanding on the nature of intermolecular interactions within crystal structures of 2–4 . The large number of F···H/H···F, H···O/O···H, H···H, and H···C/C···H contacts revealed by HSA indicates that hydrogen bonding and van der Waals interactions mainly contribute to crystal packing.

Theoretical investigation of tautomerism of 2- and 4-pyridones: origin, substituent and solvent effects

“…24 2-Pyridone is also a constituent of many biologically active natural products and pharmaceuticals, 25 DNA base analogue, 26 an important building block in synthesis 27 and shows the potential to direct molecular association by formation of hydrogen bonds. 28 The 4-pyridone structure can also be found in biologically active compounds, 29 in synthetic building blocks 30 and self-assembling building blocks, forming hydrogen bonds with extraordinary stability. 31…”

Missing puzzle in crystal engineering: 2-pyridone and [1,3,5]-triazine-2,4-diamine, the two most common cyclic hydrogen bonding sticky sites, in a single core

“…[1][2][3][4][5][6] Apart from coordination bonds, the most studied nonbonding interaction in the crystal lattice is hydrogen bonding. [7][8][9][10][11][12][13][14][15] The wide exploration of hydrogen bonds has flourished owing to advances in the organic synthesis of molecules called tectonsmolecules that are designed by grafting functional groups or sticky sites by hydrogen bonds onto a central core. 16 An important development in the field of crystal engineering in the last decade is related to the design of tectons that can form multiple intermolecular or specifically hydrogen bonding interactions to promote controlled molecular aggregation.…”