Synthesis, Spectrum, Crystal Structure and Antibacterial Activities of New Polydentate Schiff Base Ligands Containing a Pyridine Ring and Amide Moieties

Abstract

AbstractUsing highly dilute method and 5‐fold excess of diamine a new acyclic diamine containing pyridine moiety, N,N′‐bis(2‐aminoethyl)‐2,6‐pyridinedicarbamide (1a) was synthesized. Six novel linear polydentate Schiff base ligands containing pyridine and amide moieties, N,N′‐bis[β‐(R‐substitutedbenzalimino)ethyl]‐2,6‐pyridinedicar‐bamide (2a‐2e), where R=H, o‐OH, p‐OH, m‐NO2, p‐N(CH3)2, and N,N′‐bis(γ‐salicylideneaminopropyl)‐2,6‐ pyridinedicarbamide (2f) have been synthesized and characterized by elemental analysis, IR, UV‐Vis, MS and 1H NMR methods. The single‐crystal analysis of 2e showed that it belongs to triclinic system with P‐1 space group and the unit cell parameters: a=11.010(2) nm, b=13.865(3) nm, c=9.6537(19) nm, α=102.77(2) °, β=92.07(3)) °, γ=87.98(3)) °, V=1435.7(5) nm3, Z=2, Dc=1.230 mg·cm‐3, Mr=531.66. In addition, microcalorimetric test of the inhibitory capacities of these compounds for E. coli has shown that they have antibacterial activity to different extent and that of salicylidene Schiff base is the best. The structure‐activity relationship has been primarily discussed.