Structure and optical properties of new lead(II) coordination polymers and PbO nanoparticles core of polymer

Two lead(II) coordination polymers, [Pb2(4,4′-bipy)(NO3)4]n (1) and [Pb4(4,4′-bipy)2(NO3)8(PhN2O2)2]n (2), were synthesized by reaction of lead(II) nitrate with the 4,4′-bipyridine (4,4′-bipy) and cupferron ([PhN(O)NO]NH4) ligands and characterized by 1H and 13C NMR, IR, and UV spectroscopies and elemental analysis. The molecular structure of 2 was determined by single-crystal X-ray diffraction. Photoluminescence studies of complexes showed that a good correlation exists between the structures of complexes and emission wavelengths. Utilization of cupferron ligand as a second ligand in the structure of 2 resulted in a red-shift in the both absorption and fluorescence spectra and moderately enhanced the photoluminescence intensity. Lead(II) oxide core that resulted from direct thermal decomposition of complex 2 at 600 °C in air was characterized by X-ray powder diffraction and scanning electron microscopy. The photoluminescence emission spectrum of PbO nanoparticles revealed a strong blue emission band centered at 472 nm, which might be associated with oxygen vacancies.