Unprecedented double S 2À templated Ag 27 clusters have been stabilized by 5,10,15,20-tetra(4-pyridyl)porphyrin (TPyP-H 2)l igands to affordarobust 2D metal-organic framework (Ag27-MOF). This silver cluster-assembled material serves as ah ighly efficient heterogeneous catalyst for the cyclization of both terminal and internal propargylamines with CO 2 under atmospheric pressure.D ensity functional theory (DFT) calculations illustrate that the high catalytic activity and broad substrate scope are attributable to the saddle-shaped metallic node in Ag27-MOF,w hichf eatures an accessible platform with high-density silver atoms as p-Lewis acid sites for activating C Ctriple bonds.Asaresult, different sterically hindered alkyne substrates can be effectively activated through p-interactions with these cationic silver centers.
With the development of researches, the treatments of wastewater have reached a certain level. Whereas, heavy metals in wastewater cause special concern in recent times due to their recalcitrance and persistence in the environment. Therefore, it is important to get rid of the heavy metals in wastewater. The previous studies have provided many alternative processes in removing heavy metals from wastewater. This paper reviews the recent developments and various methods for the removal of heavy metals from wastewater. It also evaluates the advantages and limitations in application of these techniques. A particular focus is given to innovative removal processes including adsorption on abiological adsorbents, biosorption, and photocatalysis. Because these processes have leaded the new trends and attracted more and more researches in removing heavy metals from wastewater due to their high efficency, pluripotency and availability in a copious amount. In general, the applicability, characteristic of wastewater, cost-effectiveness, and plant simplicity are the key factors in selecting the most suitable method for the contaminated wastewater.
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