Crystal structure, thermal, luminescent and terahertz time domain spectroscopy of magnesium N-phthaloyl-beta-alaninate: A combined experimental and theoretical study

Abstract

A magnesium complex using N-phthaloyl-beta-alanine (NPA) as ligand was synthesized and its crystal structure was characterized by single-crystal X-ray diffraction analysis. The Fourier transformation infrared spectroscopy (FTIR), thermogravimetry (TG) and differential thermal analysis (DTA), fluorescence spectroscopy and terahertz time-domain spectroscopy (THz-TDS) were performed for magnesium N-phthaloyl-beta-alaninate (MgNPA). The coordination geometry around Mg (II) has found to be distorted octahedral and the coordination mode of NPA in MgNPA is monodentate i.e. eta(1)mu(1). The significant enhancement was observed in the emission intensity of MgNPA complex as compared to the ligand NPA during solid state photoluminescence spectroscopy. The computational investigations of the complex were carried out at B3LYP/6-31 + G (d,p) level in gas phase to support our experimental results. The small energy gap between frontier molecular orbitals (FMOs) manifested that MgNPA is a very reactive, chemically soft and optically active complex. The terahertz time domain spectroscopy of the complex and ligand was performed in order to characterize as well as to find out refractive index and absorption coefficient in 0.2-3.2 THz frequency range. Both the complex and ligand shows the characteristic absorption peaks in this frequency range. The decrease in refractive index is observed by the complexation of NPA with Mg. (C) 2018 Elsevier B.V. All rights reserved.