Eleven Adducts Constructed from 4-methylbenzo[d]thiazol-2-amine and Organic Acids via Coupling of Classical H-bonds and Noncovalent Interactions

Abstract Cocrystallization of 4-methylbenzo[d]thiazol-2-amine with an array of organic acids yielded a total of 11 crystalline adducts, which have been examined by X-ray diffraction, FT-IR and elemental analysis. Their melting points were also determined. Their structural and supramolecular aspects are fully analyzed. The result reveals that at the 1-3, 5-6 and 8-10 the aryl N in the thiazole cores are protonated when the organic acids are deprotonated, the crystal packing is interpreted by the strong charge-assisted N-H⋯O H-bond from the NH+ and the deprotonated acidic groups. 4, 7 and 11 are cocrystal sustained by the neutral N-H⋯O/O-H⋯N H-bonds. Apart from the N-H⋯O H-bonds, the O-H•••O H-bonds were also present at 3, 5, 6 and 9-10. 6 has the additional O-H•••S H-bonds. The N-H•••S H-bond was occurred in 9. From the crystal packing we find that different set of additional CH-O/CH2-O/CH3-O, CH3-N, CH3-S/CH2-S, CH-CH/CH2-CH/CH2-CH2/CH2-CH3/CH3-CH3, CH-Cπ/CH3-Cπ, Cl-π, CH-π/CH3-π, NH-π, O-N, O-O, Cl-O, O-S, S-S, π-π and Cπ-π contacts contribute to the stabilization and expansion of the total framework structures. For the interplay of the various weak nonbonding interactions these structures took on homo/hetero supramolecular synthons. The recognition of the L-acid in all the multicomponent crystals is based on the typical R22(8) synthon except 6. Due to the cooperation of these weak bonds, the adducts display 1D-3D structures.