Synthesis, molecular structure, photophysical properties and spectroscopic characterization of new 1D-magnesium(II) porphyrin-based coordination polymer

Abstract

Chemical preparation, X-ray diffraction, spectral and photophysical studies were performed for H2TPBP (5,10,15,20-tetrakis[4 (benzoyloxy)phenyl] porphyrin), [Mg(TPBP)], and the [MgII(TPBP)(4,4′-bpy)2] (I) complex (4,4′-bpy = 4,4′-bipyridine). This study shows -a 1D coordination polymer chain of alternating [MgII(TPBP)] and 4,4′-bipyridine molecules located at the axial position of the magnesium(II) coordination sphere. The magnesium ion is coordinated to four nitrogen atoms from the porphyrin ring and two nitrogen atoms from the axial ligands, forming a regular octahedron. The crystal packing and the linear coordination chains for this complex are stabilized by weak inter- and intramolecular interactions involving centroids (Cg) porphyrin pyrrole and the pyridyl group of the 4,4′-bipyridine rings. Infrared (IR), proton nuclear magnetic resonance (1H NMR) spectroscopies, mass spectroscopy, and elemental analysis were also investigated to confirm the crystal structure. UV–Visible absorption spectrum of complex I displayed a red shifted Soret (430 nm) and Q (571 and 614 nm) bands due to the extended conjugation. However, fluorescence emission spectrum shows larger blue shift of ~ 41 and ~ 54 nm for Q (0,0) and Q (0.1), respectively.