Multifunctional Luminescent Sensor Based on the Pb²⁺ Complex Containing a Tetrazolato Ligand

Area of Science:

• Coordination Chemistry
• Materials Science
• Luminescence

Background:

• Polydentate tetrazolato ligands offer versatile coordination possibilities.
• Lead(II) complexes are known for their diverse luminescent properties.
• Developing novel luminescent materials for sensing applications is an active research area.

Purpose of the Study:

• To synthesize and characterize novel luminescent lead(II) complexes using tetrazolato ligands.
• To investigate the luminescence properties, including emission origin and temperature dependence.
• To explore the potential of these complexes as sensors for temperature and volatile compounds.

Main Methods:

• Synthesis of lead(II) complexes using various hydrated Pb2+ salts and polydentate tetrazolato ligands.
• Characterization using IR spectroscopy, thermogravimetric analysis (TGA), elemental analysis, X-ray crystallography, and powder X-ray diffraction (PXRD).
• Photoluminescence spectroscopy to study emission properties, quantum yields, and temperature-dependent behavior.
• Density Functional Theory (DFT) calculations to elucidate emission origins.

Main Results:

• Six luminescent lead(II) complexes were successfully synthesized and structurally characterized.
• Complex 5 exhibited significantly enhanced red-shifted emission with a high photoluminescence quantum yield (PLQY) of 16.5%.
• The emission of complex 5 showed distinct temperature-dependent behavior, including shifts and new band appearances.
• The de-ligated form of complex 5 (5-H) demonstrated sensitivity to volatile primary amines and acids, suggesting sensing capabilities.

Conclusions:

• The synthesized lead(II) complexes display interesting luminescence characteristics arising from ligand-centered transitions, metal-centered transitions, and charge transfer.
• Complex 5 is a promising candidate for sensing applications due to its tunable emission properties and sensitivity to temperature and specific chemical vapors.
• The study provides insights into the structure-property relationships of luminescent lead(II) complexes and their potential in multifunctional sensing.