Designing a new magnetically separable Pd-TiO2-CN photocatalyst for facile visible light-driven coupling reactions at room temperature

Nowadays, one of the most valuable global goals is to use environmentally benign energy sources. As an ideal renewable energy source, solar energy intended to be the most promising choice for conducting eco-friendly photocatalytic processes through its sustainable, clean, and plentiful features [1]. Considering that a great portion (44%) of sunlight devotes to the visible area, photocatalysis driven by visible light has attracted a growing interest with every passing year.The coupling reaction is one of the most popular organic reactions to deliver a wide range of complex molecules including a great number of natural products and pharmaceuticals [2]. Hiyama and Suzuki–Miyaura cross-coupling reactions are one of the most potent transformations for the effective and straightforward C–C bond formation. The resulting coupling products have extensive applications as fundamental building blocks in the synthesis of numerous structurally diverse molecules [2]. To furnish such beneficial coupling transformations, extensive efforts have been done for designing the heterogeneous Pd-based catalytic systems through the immobilization of Pd on different supports [3]. However, the majority of these heterogeneous catalysts require intensive heating, andprolonged reaction time, which may lead to undesired side reactions and compromise the stability of the catalysts. Visible light-drivenPd-based heterogeneous photocatalysis of Hiyama and Suzuki–Miyaura cross-coupling reactions are limited to just a few reportedmethods. Nevertheless, most of these procedures have witnessed one or more of the following difficulties such as high photocatalystloading, tedious and time-consuming photocatalyst isolation procedures, photocatalyst loss during the recycling, prolonged reactiontimes, unsatisfactory yields of the products, using hazardous solvents and complex photoreactors [3,4]. Thus, the necessity ofpromoting a more proficient and eco-benign photocatalytic approach to conduct these transformations through more mild conditionsis evident.Inspired by these facts and considering the development of organic transformations towards more eco-benign conditions, in this study we have synthesized a novel magnetically separable Pd-TiO2-CN photocatalyst and characterized it by various techniques. The capability of the as-synthesized photocatalyst was well investigated for Hiyama and Suzuki–Miyaura cross-coupling reactions at room temperature under visible light irradiation (Scheme 1).

کلیدواژه ها:

Photocatalysis ، Cross-coupling reaction ، Heterogeneous catalyst ، Hiyama reaction ، Suzuki–Miyaura reaction