Simple Fabrication and Unique Fiber Growth Mechanism of Copper(I) 4-Toluenethiolate-Based Fibrous Coordination Polymer.

Coordination polymers (CPs) exhibit various distinctive properties owing to the metals incorporated in their main chains. These properties make CPs appealing for applications in optoelectronic devices and sensors and as precursors for inorganic materials with controlled morphologies. However, only a few CPs form fibrous structures, and the fabrication methods require complicated procedures, thus, limiting their range of applications. In this study, we report the easily feasible fabrication of fibrous CP, specifically, copper(I) 4-toluenethiolate (CuSAr), and investigate its unique fiber growth mechanism. The reaction of CuI and 4-toluenethiol in acetonitrile in the presence of triethylamine quickly produced aggregated CuSAr particles. With continuous stirring at ambient temperature (∼20 °C), wavy fibers grew from the surface of the aggregates, eventually forming an entangled fibrous structure. Structural evaluations of CuSAr using powder X-ray diffraction analyses revealed that the regularity of the crystal phase increased as the morphology changed from aggregated particles to fibrous structures, suggesting that the transformation was a crystallization-driven process. Additionally, the conversion of fibrous CuSAr to CuS, a known semiconductor, was demonstrated while maintaining the fiber-like structure and providing the desired materials.