A clean synthesis of bis(indolyl)methane and biscoumarin derivatives using P₄VPy–CuO nanoparticles as a new, efficient and heterogeneous polymeric catalyst

P₄VPy–CuO nanoparticles as a novel solid catalyst were synthesized using an ultrasound irradiation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier Transform Infrared (FT-IR) spectroscopy. The prepared catalyst was applied to the green, simple and highly efficient synthesis of bis(indolyl)methanes and 3,3′-(arylmethylene)bis(4-hydroxycoumarins). This methodology has some advantages such as short reaction times, environmentally friendly conditions, easy work-up, and excellent yields. This catalyst can be easily separated and re-used without any appreciable loss in its activity.