Correlation between ionic radii of metal azodye complexes and electrical conductivity

Area of Science:

• Coordination Chemistry
• Materials Science
• Solid State Physics

Background:

• Pyrazole and thiazolidinone derivatives are known for diverse applications.
• Metal complexes often exhibit unique thermal and electrical properties.
• Understanding conduction mechanisms is crucial for developing new electronic materials.

Purpose of the Study:

• To synthesize and characterize a new azo-pyrazolone-thiazolidinone ligand (HL) and its Cu(II), Co(II), and Ni(II) complexes.
• To investigate the thermal decomposition behavior and activation energies of the ligand and its metal complexes.
• To explore the frequency and temperature dependence of AC conductivity and dielectric properties, and determine the dominant electrical conduction mechanisms.

Main Methods:

• Physico-chemical characterization techniques.
• Thermal analysis (TGA/DSC) to determine decomposition patterns and activation energies.
• AC conductivity and dielectric measurements across a range of temperatures (300-356 K) and frequencies (0.1-100 kHz).

Main Results:

• The ligand (HL) and its metal complexes (Cu(II), Co(II), Ni(II)) were successfully synthesized and characterized.
• Thermal decomposition activation energies (Ea) were determined for HL (48.76 kJ/mol) and its complexes (Cu(II): 36.83 kJ/mol, Co(II): 30.59 kJ/mol, Ni(II): 40.45 kJ/mol).
• AC conductivity and dielectric properties were found to be dependent on the nature of the metal ion. Electrical activation energies decreased with increasing frequency.
• Conduction mechanisms identified: Small Polarons Tunneling (SPT) for HL, Overlapping Large Polarons Tunneling (OLPT) for Co(II) complex, and Correlated Barrier Hopping (CBH) for Cu(II) and Ni(II) complexes.

Conclusions:

• The synthesized metal complexes exhibit distinct thermal and electrical properties influenced by the central metal ion.
• The study elucidates the complex interplay between metal ions, ligand structure, and charge transport mechanisms in these coordination compounds.
• The findings contribute to understanding structure-property relationships in novel metal-organic materials for potential electronic applications.