CO2 Fixation and PCHC Depolymerization by a Dinuclear ß-Diketiminato Zinc Complex.

The production of cyclic carbonates and (or) polycarbonates from the coupling of carbon dioxide (CO2 ) with epoxides is a practical strategy for CO2 fixation. Chemically recycling of the polycarbonates is also urgently needed for sustainable development of plastics. Here a dinuclear ß-diketiminato (BDI) methyl zinc complex((BDI-ZnMe)2 , 1) is reported to achieve not only selective cyclic carbonates from cycloaddition of CO2 to meso-CHO in the presence of cocatalyst, but also effective depolymerization of PCHC into trans-CHC. The trans-CHC can be further transformed into cis-CHC, thus demonstrating great application potentials of this strategy in CO2 fixation and chemical recycling of plastics.

A sustainable approach for the synthesis of recyclable cyclic CO2-based polycarbonates.

It is highly desirable to reduce the environmental pollution related to the disposal of end-of-life plastics. Polycarbonates derived from the copolymerization of CO2 and epoxides have attracted much attention since they can enable CO2-fixation and furnish biorenewable and degradable polymeric materials. So far, only linear CO2-based polycarbonates have been reported and typically degraded to cyclic carbonates. Here we synthesize a homogeneous dinuclear methyl zinc catalyst ((BDI-ZnMe)2, 1) to rapidly copolymerize meso-CHO and CO2 into poly(cyclohexene carbonate) (PCHC) with an unprecedentedly cyclic structure. Moreover, in the presence of trace amounts of water, a heterogeneous multi-nuclear zinc catalyst ((BDI-(ZnMe2·xH2O)) n , 2) is prepared and shows up to 99% selectivity towards the degradation of PCHC back to meso-CHO and CO2. This strategy not only achieves the first case of cyclic CO2-based polycarbonate but also realizes the complete chemical recycling of PCHC back to its monomers, representing closed-loop recycling of CO2-based polycarbonates.

Dicyanoisophorone-based fluorescent probe with large Stokes shift for ratiometric detection and imaging of exogenous/endogenous hypochlorite in cell and zebrafish.

A novel dicyanoisophorone-based red-emissive fluorescence probe (YT) with large Stokes shift (230 nm) was synthesized for rapid (<20 s) and selective detection of hypochlorite ions in nearly 100% aqueous medium. YT responded to hypochlorite ions via the ClO--promoted oxidative deprotection of thioacetal, leading to a red shift in its fluorescence maximum from 590 nm to 640 nm accompanied by naked-eye color change from orange to red. The emission response of the probe toward ClO- presented a good linear relationship in the 5-160 µM concentration range, with the LOD of 4.64 µM. Further, the probe YT was successfully employed in exogenous and LPS-induced endogenous imaging of ClO- in live cells and zebrafish, demonstrating its potential applications in biological science.