Synthesis and structural characterization of novel di-substituted pyridine-2,6-dicarboxylic acid hydrazide oxo-quinazoline derivative and Cu(II) pincer complex.

The crystal and molecular structure of di-substituted pyridine-2,6-dicarboxylic acid (pdc) hydrazide derivative containing quinazoline moieties was determined. A non-planar molecule with a specific N , N , N -chelate binding site. A novel Cu(II) complex with the ligand molecule was prepared. Coordination geometry is a square pyramid, hydrazide atoms are in deprotonated anionic form, and quinazoline N atoms are in protonated cationic form. [Display omitted] • Pyridine-2,6-dicarboxylic acid hydrazide quinazoline derivative. • Ligand with N , N , N -chelate binding sites suitable for the complexation of metal ions. • Square pyramidal Cu(II) complex compound. • Hydrazide atoms in the anionic form, and N -quinazoline atoms in the cationic form. • Dimer motif in the structure of the ligand and π ⋯ π interactions in the Cu(II) complex. Crystal and molecular structures of novel pyridine-2,6-dicarboxylic acid (pdc) hydrazide derivative (H 2 L) dimethanol solvate (H 2 L = N,N'-bis(2-methyl-4-oxoquinazolin-3(4H)-yl)pyridine-2,6-dicarboxamide) and its copper(II) complex were determined by the single-crystal X-ray diffraction. In the crystal structure, these non-planar molecules form specific cavities that are populated by methanol molecules (held by O H⋯O and N H⋯O hydrogen bonds). Additional stabilization is achieved through a series of offset face-to-face π ⋯ π interactions between aromatic moieties. The compound is the first structurally described pdc hydrazide derivative containing quinazoline moieties. The reaction of the H 2 L with copper(II) chloride in methanol resulted in the formation of a new methanol/water solvate containing discrete CuCl 2 L molecules. Cu(II) ion is coordinated by three nitrogen atoms (two from hydrazide and one from pyridine moieties) in a chelate fashion. Two chloride ions complete distorted square pyramidal coordination geometry. Unlike in H 2 L molecules, in CuCl 2 L the hydrazide N -atoms are deprotonated, and coordinated to Cu(II), while quinazoline N -atoms are protonated. In its crystal structure, CuCl 2 L molecules form dimeric motifs via O H⋯O, N H⋯O, O H⋯Cl hydrogen bond interactions. The adjacent dimers are stacked along the crystallographic b - and c -axis through N H⋯Cl and offset face-to-face π ⋯ π interactions. The FT-IR spectra analysis indicates a significant shift of C O stretching vibrations of uncoordinated carbonyl groups, that can be attributed to the electron-withdrawing effect of Cu(II) ion. The TG analysis indicates that the weakly bounded solvent molecules evaporate at lower temperatures and that the compound is stable up to 300 °C. [ABSTRACT FROM AUTHOR]