A new copper(I) coordination polymer from 2,6-bis(1H-benzotriazol-1-ylmethyl)pyridine: Synthesis, characterization, and use as additive in transparent submicron UV filters

Abstract

The use of a new copper(I) coordination polymer (CP) as additive in transparent composite films of 190 nm of thickness for ultraviolet (UV) shielding is presented. The luminescent 1-D Cu(I) CP was easily synthesized through a self-assembly process between Cu(I) iodide and 2,6-bis(1H-benzotriazol-1-ylmethyl)pyridine (L). The CP, [Cu₂(μ − I)₂(μ − L)₂]_n, was structurally characterized by infrared, UV–visible diffuse reflectance and photoluminescence spectroscopy, elemental and thermogravimetric analyses, single-crystal and powder X-ray diffraction, and relativistic density functional theory calculations. The CP was dispersed and immobilized into a polymeric matrix in the presence of Sudan I, yielding a composite material that exhibits a reduction of 49% of the UV transmittance at 350 nm. Thus, the use of a new Cu(I) CP in polymeric composite films appears as a novel approach toward ultrathin and transparent UV shielding films, which have potential applications as protection layers of paints and coatings that tend to degrade when exposed to UV radiation.

Keywords:

• Copper(I) coordination polymer
• crystal structure
• luminescence
• polymeric composites
• ultraviolet filters

Acknowledgements

The authors thank the clean room from the Department of Electrical and Electronics Engineering, the Department of Chemistry, and the School of Science of the Universidad de los Andes for financial support. N. Nuñez-Dallos is also grateful with COLCIENCIAS for his doctoral scholarship (Conv. 617). A. Muñoz-Castro acknowledges the financial support given by FONDECYT 1140359. We also thank Dra. Lorena Barrientos for her help in the UV–vis diffuse reflectance spectroscopy measurements. We thank the reviewers and editor for their useful comments.