The photocatalytic conversion of CO2 to valuable fuels or chemicals has displayed the promise to solve urgent energy and environmental problems. Photocatalytic systems for CO2 reduction in water usually suffer from low efficiency and selectivity due to competitive proton reduction and relatively low CO2 concentration. In this work, we report a CoII–ZnII heterometallic dinuclear complex [CoZn­(bpbp)­(CH3COO)2]­(CH3COO) (CoZn), which shows high photocatalytic activity and selectivity for CO2-to-CO conversion in a water/acetonitrile solution. The values of TONCO and CO selectivity reach as high as 6680 and 98%, respectively. It was found that CoZn exhibits much higher activity than the corresponding CoII–CoII homometallic dinuclear complex [Co2(bpbp)­(CH3COO)2]­(CH3COO) (CoCo) under the same conditions. The electrochemical properties and DFT calculations indicated that the improved photocatalytic activity of CoZn in comparison to CoCo is attributed to the smaller energy barrier of the rate-limiting CO2 coordination step for photocatalytic CO2-to-CO conversion via the synergistic effect between the two different metal centers.

The development of cost-effective catalysts for CO2 reduction is highly desired but remains a significant challenge. The unsaturated coordination metal center in a catalyst is favorable for the process of catalytic CO2 reduction. In this paper, two asymmetric salen ligands were used to synthesize two coordinatively unsaturated Co-salen complexes. The two Co-salen complexes exhibit an unsaturated coordination pattern and display high activity and CO selectivity for visible-light-driven CO2 reduction in a water-containing system. The photocatalytic performance of 2 is higher than that of 1 because the reduction potential of the catalytic CoII center and the energy barrier of the catalytic transition states of 2 are lower than those of 1, with turnover numbers (TONCO), turnover frequencies (TOF), and CO selectivity values of 8640, 0.24 s–1, and 97% for 2, respectively. The photocatalytic reduction of CO2 to CO for 2 is well supported by control experiments and density functional theory (DFT) calculations.

According to the principles and methods of ecology and system engineering, we set up an evaluation indicator system for multi-component and multiple cropping systems, evaluated the comprehensive benefits of multi-component and multiple cropping systems using grey relation clustering analysis and screened out the optimized model based on research done in the upland red soil in Jiangxi Agricultural University from 1984 to 2004. The results show that the grey relation degree of ''cabbage/ potato/maize 2 sesame'' was the highest among 23 multi-component and multiple cropping systems and was clustered into the optimized system. This indicates that ''cabbage/potato/maize 2 sesame'' can bring the best social, economic and ecological benefits, increase product yield and farmers' income and promote sustainable development of agricultural production. Therefore, it is suitable for promotion on upland red soil. The grey relation degree of ''canola/Chinese milk vetch/maize/mung bean/maize'' was second, which is suitable for implementation at the city outskirts. In conclusion, these two planting patterns are expected to play important roles in the reconstruction of the planting structure and optimization of the planting patterns on upland red soil.

No abstract

Our previously reported copper-based complexes of tropolone show nice antitumor effects, but with high cytotoxicity to normal cells, which is presumably caused by copper ions. Here we managed to achieve this challenge by using other 3d metals to replace copper ions. We thus prepared four mononuclear 3d Metal complexes [M(phen)L2] (M = Mn, Co, Ni, Zn for 1–4, respectively). Complexes 1 and 4 show selectivity on different cancer cell lines with much lower cytotoxicity to normal cells than cisplatin. The anti-cancer effects for complexes 2 and 3 on the tested cancer cell lines are very poor. It revealed a tuning effect of different metal ions on the anti-cancer activities with that for Mn(II) and Zn(II) being much higher than that for Co(II) and Ni(II) in this system. Among of them, complex 1 presents a best anti-cancer effect on Hela cells comparable to cisplatin. It overcame the afore-mentioned shortage of high cytotoxicity to normal cells for the reported Cu(II) complexes. It revealed from the mechanistic studies that complex 1 mainly induces apoptosis through the mitochondrial pathway by increasing intracellular ROS, releasing Ca2+, activating Caspase 9 and pro-apoptotic gene Bax.