Synthesis of highly pure poly(aryleneethnylene)s using palladium supported on calcium carbonate as an eco-friendly heterogeneous catalyst

摘要

Metal catalyst contamination is a major concern in the preparation of polymeric materials. For conjugate polymers, trace amount of metal catalyst is detrimental to the optoelectronic properties. In this work, a method for synthesizing highly pure fluorescent polymers, poly(aryleneethynylene)s (PAEs), was developed using heterogeneous Pd/CaCO3 catalytic system. Polymerization between a variety of aryl diethynes and aryl diiodides or dibromides were achieved using a catalytic amount of Pd/CaCO3, CuI, and PPh3 at 80 degrees C in good to excellent yields (79-100%). Resulting polymers possess degree of polymerization ranging from 8 to 50 with polydispersity index of 1.5-3.6. Importantly, PAEs from Pd/CaCO3 catalytic system contain considerably lower level of Pd and Cu contamination (1.9 and 3.4 ppm, respectively) than those obtained from classical homogeneous catalyst, Pd(PPh3)(4) and PdCl2(PPh3)(2) or heterogeneous catalyst Pd/C. (c) 2019 Wiley Periodicals, Inc.