Single Site W(0) versus Re(I)-Dipyridophenazine- Based Conjugated Porous Polymer for CO2 Photoreduction

Herein, the synthesis and characterization of two robust tungsten and rhenium carbonyl complexes integrated into an organic polymer (CPP-Re, CPP-W) are reported. These polymers are obtained by a Suzuki coupling reaction between the corresponding dibromo metal-carbonyl substituted dipyrido[3,2-a:2′,3′-c]phenazine complex and 1,3,5-triphenylbenzene-4′,4″,4″,4‴-triboronic acid and integrated catalytic active sites and photosensitizer since they have not only nitrogen sites to coordinate metal active centers as rhenium or tungsten but photoactive units with good charge-separating ability which can significantly improve the CO₂ photoreduction reaction (CO₂PRR). These polymers show similar activity in solid–gas CO₂PRR in absence of sacrificial agents to produce syn gas (CO + H₂) but CPP-W selectivity to products change regarding CPP-Re being able to produce also large amount of more demanding electron products such as methane and ethane. Moreover, the single-site Re- or W-CPP catalysts could prevent the dimerization of complexes that produces its deactivation. This work shows the potential of CPPs as matrices to support single active centers for heterogeneous catalysis.