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?

CrystEngComm Pub Date: 2023-01-13 DOI: 10.1039/D2CE01505F

Abstract

Herein, we report a facile method for the synthesis of eight structurally diverse compounds 1–8 bearing hydrogen bonding functional group – diaminotriazine (DAT) along with pyridine and polyether groups for 1–4 and DAT linked via C–C bond to a 2-pyridone for 5–8. These compounds are positional isomers and vary from each other in the position of DAT group with respect to the pyridine-nitrogen atoms. The successful synthesis of 1–8 was confirmed by infrared, mass spectrometry, and 1H and 13C nuclear magnetic resonance. Molecular structures and aggregations in the solid state of 1–5, and 7 were elucidated by single crystal X-ray diffraction (SCXRD) and showed predictable hydrogen bonding motifs for the DAT group. Among the four compounds with polyether chains, only 4 show an interdigitated pattern. The 2-pyridone group (in 5 and 7) shows none of the expected typical hydrogen bonding patterns. Rather, a heteroleptic hydrogen bonding motif involving the free hydrogen atom of the DAT group and the oxygen atom from the pyridones is observed. Overall, these hydrogen-bonded networks are mainly composed of layers (1 & 5), tapes (2), ribbons (3 & 7), and chains (4).

Graphical abstract: 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
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