Anion-controlled dimerized rectangular, herringbone and tape building blocks by L-shaped diamide-substituted pyridinium saltsvia N–H⋯O and C–H⋯O hydrogen bonding

Abstract

A series of 1-(2-amino-2-oxoethyl)-4-carbamoylpyridin-1-ium salts with different anions (PF₆⁻ (1), OTf⁻ (2), BPh₄⁻ (3) and Br⁻ (4)) have been synthesized and characterized by single crystal X-ray diffraction. The results demonstrate that the unparallel diamide-substituted pyridinium salts form a dimerized rectangular building block and a 2-D rectangular structure via N–H⋯O and C–H⋯O hydrogen bonding (PF₆⁻ (1) and OTf⁻ (2), respectively), a 2-D sheet structure (BPh₄⁻ (3)) via N–H⋯O hydrogen bonding catemers and a 2-D plate structure via N–H⋯O and C–H⋯O hydrogen bonding catemers (Br⁻ (4)). The effects on the hydrogen bonding motifs, building blocks and structures by the four anion species with different hydrogen bonding acceptor abilities, sizes and shapes have been discussed.