Supramolecular interactions between a diamine-diamide ligand and anions, trigonal planar NO3- and spherical Cl-: Multiple hydrogen bond cooperativity through water molecules

摘要

Supramolecular interactions between NO3- and CI- and the diamine-diamide ligand, N,N'-propane-1,3-diyl-bis-(2-aminobenzamide) (PBAB), are reported. The diprotonated PBAB interacts with anions, trigonal planar NO3- and spherical CI-, resulting in H-bonded supramolecular entities. Formation of the anion complexes is established by the pH-potentiometric and electronic spectral studies in solution. Comparison of the mass, IR and H-1-NMR spectra of the free ligand with the salts of NO3- and CI- confirm the formation of the complexes. Single crystal X-ray diffraction investigations of the solids reveal the stoichiometry, structures of the complexes and rich variety of hydrogen bond motifs involving the protonated amine (-NH3+), amide -NH, alkyl and aryl -C-H, H2O and anions and pi-pi interactions between adjacent cations. Unlike the free ligand (triclinic, P-1) and the chloride ion adduct (monoclinic, P2(1/)c), the nitrate salt is found to be centrosymmetric (monoclinic, C-2/c).