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Luminescent polymorphic aggregates of trinuclear Cu(I)-pyrazolate tuned by intertrimeric CuNPy weak coordination
Shun-Ze Zhan1, Wei Chen1, Ji Zheng2
1Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou 515063, P. R. China. szzhan@stu.edu.cn.
Dalton Transactions (Cambridge, England : 2003)
|January 18, 2021
Summary
This study reports five novel luminescent polymorphic aggregates of trinuclear copper(I)-pyrazolate complexes. These aggregates exhibit unique conformations and luminescence properties, offering new avenues in supramolecular chemistry.
Area of Science:
- Coordination Chemistry
- Supramolecular Chemistry
- Materials Science
Background:
- Copper(I) complexes with pyrazolate ligands are known for their diverse structures.
- Understanding the factors influencing the formation and properties of polynuclear copper aggregates is crucial for developing new functional materials.
Purpose of the Study:
- To synthesize and characterize five luminescent polymorphic aggregates of trinuclear Cu(I)-pyrazolate complexes.
- To investigate the structural diversity, conformational variations (syn- and anti-), and luminescence mechanisms of these aggregates.
- To explore the transformation of solvated complexes into unsolvated forms and the role of intertrimeric interactions.
Main Methods:
- Single-crystal X-ray diffraction for structural determination.
- Spectroscopic analysis (UV-Vis absorption and photoluminescence) to study optical properties.
- Thermogravimetric analysis to investigate solvent evacuation and structural transformation.
Main Results:
- Five distinct luminescent polymorphic aggregates, [anti-Cu3L3]2 (1), [syn-Cu3L3·C2H5OH]2 (2), [anti-Cu3L3·C2H5OH]n (3), [anti-Cu3L3·0.5C7H8]n (4), and [syn-Cu3L3·C8H10]n (5), were successfully synthesized and characterized.
- The aggregates display syn- and anti-conformations of the trimeric Cu3L3 fragments, influenced by the orientation of pyridyl groups.
- Intertrimeric NPyCu weak coordination bonds and CuCu interactions contribute to the stability of dimeric and polymeric structures.
- Solvated complexes can be converted to the unsolvated form (1) upon heating.
- Luminescence emission spans from green to yellow under UV irradiation, attributed to triplet metal-to-ligand charge transfer (3MLCT) states mixed with intertrimeric CuCu interactions.
Conclusions:
- This work presents a novel class of supramolecular aggregates based on the Cu3Pz3 core, expanding beyond traditional adducts and metallophilic interactions.
- The study highlights the role of ligand conformation, solvent molecules, and intertrimeric interactions in dictating the structural diversity and luminescent behavior of copper-pyrazolate systems.
- These findings offer a new platform for designing luminescent coordination materials with tunable properties.
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