Electrochemical studies and Thermodynamic Parameters of tris(2,2'-bipyridyl) ruthenium (II) in nonaqueous Solutions
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Electrochemical studies and Thermodynamic Parameters of tris(2,2’-bipyridyl) ruthenium (II) in nonaqueous Solutions Gendensuren Bolormaa1, Munkhbat Battulga1, Batjargal Naranbileg1, Baatar Battsengel1 and Chimed Ganzorig1 1
Center for Nanoscience and Nanotechnology and Department of Chemical Technology, School of Chemistry and Chemical Engineering, National University of Mongolia, University Street, 14704, Ulaanbaatar, Mongolia
ABSTRACT In this study Ruthenium (II) tris (2, 2’-bipyridyl) complex in nonaqueous solution was studied by cyclic voltammetry and also its kinetic parameters were calculated. The redox reaction of ruthenium (II) trisbipyridyl complex is totally quasi-reversible and it can be described as a diffusion-controlled process. As a result of the redox reaction, the kinetic parameters of the electrode process such as diffusion coefficient (D), and heterogeneous rate constant (ks) were calculated. In addition, the different thermodynamic parameters such as standard free energy (ΔG#), enthalpy change (∆H#), and entropy change (∆S#) were determined and enthalpy change revealed the exothermic behavior of the electrode reaction. Both oxidation and reduction onset potentials of the ruthenium (II) trisbipyridyl complex was determined under the same experimental conditions to estimate the low ionization potential and electron affinity. The electrochemical and optical band gaps of the ruthenium (II) complex were compared. INTRODUCTION The study of kinetics and thermodynamics of organometallic materials (Ru- complexes) for OLED and ECL technologies is important in order to exhibit electrochemical stability and reversible redox behavior of these organic materials. The knowledge of the energy levels of related molecules facilitates the tailored fabrication of these technologies with a defined recombination zone for the acceptors and donors. The electrochemical processes are similar to the charge injection and transport in ECL and OLED. Electrochemical stability, reversibility or redox behavior and energy levels of various materials used in organic LEDs, and kinetic properties of the ruthenium (II) trisbipyridyl complex are relatively new field. The spectroscopic and electrochemical properties of transition metal complexes are typically described using molecular orbital. Ruthenium (II) polypyridine complexes in general have been extensively studied because of their unique redox and photochemical properties. A typical example of such complexes is tris(2,2’-bipyridyl) ruthenium (II). Light-emitting electrochemical cells based on thin films (~100 nm) of salt of tris(biprydine) ruthenium(II) [Ru(bpy)32+ bpy= 2,2′-bipyridine)] and its derivatives that have been studied recently in [1-3] show good quantum efficiency and low operating voltages, but still rather modest operating lifetimes. The redox properties of Ru(bpy)32+ play an important role in numbers of applications. In this study electrochemical techniques were used to determine the kinetic and thermodynamic parameters of electrode reaction of tris(biprydine) ru
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