Photocatalytic reductive carboxylation of terminal alkynes with CO2 using heterostructured ZIF-7/BiOBr under visible-light illumination

• Published in: Journal of CO2 utilization 2023-01, Vol.67, p.102334, Article 102334
• Main Authors: Bhatt, Sakshi, Malik, Anil, Soni, Aishwarya, Moses Abraham, B., Sen, Arghya, Jain, Suman L.
• Format: Article
• Language: English
• Subjects: CO2; Heterojunction; Photocatalyst; Reductive carboxylation; Terminal alkyne
• ISSN: 2212-9820; 2212-9839
• DOI: 10.1016/j.jcou.2022.102334

Carboxylation of the organic compounds utilizing CO2 is a challenging task because of the higher thermodynamic stability and chemical inertness of the CO2 molecule. In the present study a straight protocol for the reductive carboxylation of terminal alkynes with CO2 has been developed, providing regioselective synthesis of α, β-unsaturated carboxylic acids using a heterostructured photocatalyst composed of Zn-benzimidazolate framework (ZIF-7) and BiOBr without any additional reducing agent at room temperature and atmospheric pressure conditions. The electron rich derivatives of phenyl acetylene substrates afforded α-acids; whereas, electron deficient substrates provided terminal acids. The DFT calculations indicated the type-II band alignment nature of ZIF-7/BiOBr in which electrons migrated from the ZIF to BiOBr and interacted with CO2 to generate CO2 radical anion at the conduction band of BiOBr. •First photocatalytic coupling of terminal alkynes with CO2 without additional reducing agent.•Facile synthesis of hybrid materials composed of (ZIF-7) and BiOBr.•DFT calculations indicated the type-II band alignment of ZIF-7/BiOBr.•Photogenerated electrons flow from ZIF-7 to BiOBr in the active catalyst and react with CO2 to give CO2.-.•Photo-oxidation of alkyne at the VB of the composite provide radical cation.