Self-assembly of seven diamide-containing pyridinium saltsvia nonconventional C–H⋯O hydrogen bonding catemers

Abstract

A series of 1-(2-amino-2-oxoethyl)-3-carbamoylpyridin-1-ium salts with different anions (Cl⁻, Br⁻, BF₄⁻, NO₃⁻, OTf⁻, PF₆⁻ and BPh₄⁻) have been synthesized and characterized by single crystal X-ray diffraction. The results demonstrate that the L-shaped diamide pyridinium cations can aggregate convergently to form a tubular structure or divergently to form a one-dimensional ribbon structure or two-dimensional brick, grid and sheet structures via different hydrogen bonding catemer motifs, including conventional N–H⋯O type (BPh₄⁻ (7)), the nonconventional N–H⋯O types (Cl⁻ (1)) and, the mixed N–H⋯O/C–H⋯O type (OTf (5) and PF₆⁻ (6)), and the interesting pure C–H⋯O types (Cl⁻ (1), Br⁻ (2) and BF₄⁻ (3)).