Efficient CO_(2) electroreduction coupled with semi-dehydrogenation of tetrahydroisoquinoline by MOFs modified electrodes

Electroreduction of CO_(2) into formate catalyzed by metal-organic frameworks(MOFs) is a promising avenue to promote the carbon cycle,but the oxygen evolution reaction(OER) process in anode usually limited the reaction efficiency.Here,a new framework {(Me_(2) NH_(2))[Bi(L)]·4 DMF·2 H_(2) O}_n(V12) was constructed and structurally characterized(L=5,5'-(1,3,6,8-tetraoxo-1,3,6,8-tetrahydrobenzo [lmn][3,8]phenanthroline-2,7-diyl) dibenzene-1,3-dicarboxylic acid;DMF=N,N-dimethylformamide).V12 possesses large one-dimensional channels with the size of 1.5 × 0.7 nm and exhibits good stability in common solvents.After V12 was modified on electrode via electrodeposition,as-synthesized sample exhibits impressive catalytic performance for the transformation of CO_(2) into formate with Faraday efficiency of93.2% and current density of 11.78 mA cm^(-2) at-0.9 V(vs.RHE).Control experiments revealed that the MOFs electrodeposition strategy significantly improves the charge transfer rate and introduces more structural defects,which promotes the reaction activity.Moreover,tetra hydroisoquinoline is added as an accelerant in the anode to achieve the simultaneous generation of formate and dihydroisoquinoline.More importantly,the cell voltage is reduced from 2.79 to 2.52 V at 10 mA cm^(-2) in a two-electrode system due to more positive reaction kinetics.This work provides an enlightening strategy for using MOFs to establish an effective system to achieve CO_(2) reduction while obtaining high value-added oxidation products.

Highly selective and eco-friendly dihydroisoquinoline synthesis via Cu/Co synergistic catalysis in Cu NPs@MOFs catalyst under mild conditions

3,4-Dihydroisoquinoline(DHIQ)is an important precursor used in the production of drugs for treating cancer,HIV,Alzheimer's disease,etc.Major studies on DHIQ synthesis show low catalytic selectivity due to the susceptible over-oxidation feedstock of1,2,3,4-tetrahydroisoquinoline(THIQ),which often requires alkali co-catalysts.Therefore,it is desirable yet challenging to explore a highly selective and efficient oxydehydrogenation capacity for DHIQ synthesis under eco-friendly reaction conditions.Herein,a novel framework 1 was synthesized,exhibiting 1D channels with the size of 4.6 A×9.6 A and high solvent/p H/thermal stability.A stable framework allows it to encapsulate Cu nanoparticles(NPs)to form Cu NPs@1-x(x=1,2,3,and 4)with varying loading amounts of Cu NPs at 2.0 wt%,3.0 wt%,4.0 wt%,and 6.0 wt%,respectively.Cu NPs@1-3 could selectively catalyze the reaction from THIQ to DHIQ with a high selectivity of 98%and a recorded turnover frequency(TOF)of 22.1 h-1under eco-friendly mild conditions.The corresponding catalytic activity can maintain at least five recyclings and can be further applied to gram-scale experiments.Additionally,the efficient preparation of DHIQ catalyzed by Cu NPs@1-3 could be realized even under air conditions.Importantly,the anticancer molecule precursor synthesis of 6,7-dimethoxy-3,4-dihydroisoquinoline was also selectively catalyzed by Cu NPs@1-3.Mechanism investigations revealed that high catalytic performance can be attributed to the stable framework and the synergistic catalytic effect of the loaded Cu NPs and Co metal centers.More importantly,this work represents the first example of MOF catalysts for selectively thermo-catalytic DHIQ synthesis and demonstrates a simple approach to obtain efficient catalysts for selective oxydehydrogenation in the production of unsaturated compounds.