Abstract
ABSTRACTA series of novel complexes of La(III) with substituted pyrazolines and mixed ligand complexes with these pyrazolines and thio-ligands have been synthesized and characterized by elemental analysis, molecular weight measurement, Fourier transform infra-red, 1H and 13C NMR spectroscopy. The particle/crystallite sizes were confirmed by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopic techniques. Optical characterizations have been performed by electronic absorption and fluorescence emission spectroscopies in order to investigate their luminescence behaviour, which reveals fairly good quantum yield and fluorescence life time for some of the complexes. Thermal analyses such as thermogravimetric and differential thermal analysis indicate that these complexes are thermally stable at high temperature. Investigations pertaining to solid-state optical absorption spectra and photoelectron yield spectroscopy reveal that upon thermal annealing beyond 300°C, these compounds form dark-brown to black semiconducting materials with an optical band gap between 1.9 and 2.3 eV.Abbreviations: La-PyH : La-HPY = [La(C15H12N2OH)2(H2O)Cl]; La-PyH-dtc = [La(C15H12N2OH)(C5H10NS2)(2H2O)Cl]; La-OCPy-xan: [La(C15H12N2OOCH3)(C2H5OCS2)(2H2O)Cl]
Highlights
Conceiving the importance of lanthanides in different fields, such as organic light emitting diodes (OLEDs), liquid crystals, fluoroimmunoassays, laser technology, optical telecommunication systems [1,2], there are much concern about the study of the lanthanide complexes
In continuation of our previous work [44,45,46], we have investigated the complexation behaviour of various substituted pyrazolines and thio-ligands with lanthanum(III) followed by the characterization of the resulting complexes by various analytical as well as photo-physical techniques
The IR spectral data indicate the bidentate mode of coordination of pyrazoline, dithiocarbamate and xanthate ligands
Summary
Conceiving the importance of lanthanides in different fields, such as organic light emitting diodes (OLEDs), liquid crystals, fluoroimmunoassays, laser technology, optical telecommunication systems [1,2], there are much concern about the study of the lanthanide complexes. Pyrazoline rings are capable of influencing photo-physical properties of lanthanides [20] resulting in the antenna effect in the complexes [42] Considering these important properties of pyrazolines, we have chosen it as the main ligand of our complexes. In continuation of our previous work [44,45,46], we have investigated the complexation behaviour of various substituted pyrazolines and thio-ligands with lanthanum(III) followed by the characterization of the resulting complexes by various analytical as well as photo-physical techniques. Investigation of their luminescence behaviour was conducted utilizing electronic absorption, fluorescence emission and fluorescence life-time studies.
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