Functionalized Covalent Triazine Framework (CTF) for Catalytic CO<sub>2</sub> Fixation and Synthesis of Value-Added Chemicals
Ram Kishan, Pooja Rani, Gulshan Singh, C. M. Nagaraja
Abstract
The capture and utilization of CO 2 for sustainable synthesis of commodity products represent a significant move toward mitigating the growing atmospheric CO 2 content for environmental remediation. Meanwhile, Suzuki-Miyaura and Mizoroki-Heck cross-coupling reactions are considerable tools for generating valuable feedstock compounds, such as agrochemicals, natural products, drugs, etc. In this regard, we present the strategic incorporation of catalytically active Pd(II) in a porous covalent triazine framework (CTF) composed of bipyridine sites (bpy-CTF) by postsynthetic modification. Notably, Pd(II) anchored framework, Pd(II)@bpy-CTF, demonstrated exceptional catalytic function in the cyclization of CO 2 with propargylic amines and in cross-coupling reactions (Heck and Suzuki-Miyaura), producing high-value commodity products under mild conditions. Further, various electronically and sterically challenging substrates were converted into the corresponding products by using Pd(II)@bpy-CTF as a catalyst. Notably, Pd(II)@bpy-CTF exhibited efficient reusability, sustaining eight catalytic cycles without substantial degradation. The exceptional catalytic behavior of Pd(II)@bpy-CTF is accredited to high abundance of N-rich triazine units and the exposed catalytic Pd(II) sites within the one-dimensional channels of the CTF. This work establishes the potential utility of triazine-based frameworks for utilizing carbon dioxide and stabilizing catalytically active metal ions in developing highly recyclable catalysts to generate value-added chemicals efficiently.