Polyhydroxyurethanes from Biobased Monomers and CO_(2):A Bridge between Sustainable Chemistry and CO_(2) Utilization

Polyhydroxyurethanes(PHUs)have received considerable attention in the last decade as potential alternatives to traditional phosgene-based polyurethanes(PUs).The development of suitable 5CC(five membered-ring cyclic carbonate)precursors bearing multiple carbonate moieties(multi-5CCs)is a key requisite for preparing PHUs by polyaddition reaction with bis-or polyamines.Producing sustainable PHUs from CO_(2)-based five-membered cyclic carbonates(5CCs)obtained from biobased epoxides is a valuable strategy to bridge CO_(2) utilization and the upcycling of renewable substrates.In this context,while many multi-5CC monomers reported in the literature are oil-based,recent efforts have led to the development of a large variety of multifunctional 5CCs that are produced by the combination of CO_(2) and renewable resources such as fatty acids and vegetable oils,lignin,terpenes,and sugars.In this work,recent crucial advances(2019—2023)on PHUs prepared from bis-and multi-5CCs produced from CO_(2) and(partially/potentially)biobased substrates are reviewed with respect to their synthesis,thermal and mechanical properties,and their recent,emerging applications.

Observatory science with eXTP

In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.

The importance of the bite angle of metal(Ⅲ) salen catalysts in the sequestration of CO_(2) with epoxides in mild conditions

Located in the middle of the fever to solve the problem of CO_(2)emissions in the environment,CO_(2)sequestration by reaction with epoxides is one of the key tools,as it not only fixes CO_(2),but also makes it functional by leading to cyclic carbonates.Herein,the results are focused specifically on the formation of cyclic organic carbonates catalyzed by metal-salen complexes,previously achieved with yttrium and scandium,that are compared with those of analogous complexes containing metals from the first transition series,such as cobalt or chromium.Density functional theory(DFT)calculations allow to determine whether this switch of metals will be feasible and provide the basis for instigating future experimental efforts in this regard.The calculations analyzing the structure and electronics of the catalysts allow us to give not only a clear picture of whether these catalysts will be efficient,but also allow us to assess which metal center is the most convenient and/or whether the catalytic reaction will occur under mild conditions.Advanced buried volume calculations with the SambVca packages shed light on the different catalytic pockets of monometallic first row transition metals vs.group III salen complexes.Our predictive catalysis results show that the bite O-M-O angle plays an essential role in the catalysis.

Surface science approach to the heterogeneous cycloaddition of CO_(2) to epoxides catalyzed by site-isolated metal complexes and single atoms: a review

The cycloaddition of CO_(2) to epoxides to afford cyclic organic carbonates is an increasingly relevant non-reductive strategy to convert CO_(2) to useful products able to serve as high-boiling solvents,chemical intermediates,and monomers for the preparation of more sustainable polymers.The development of efficient and robust hetero-geneous catalysts for such transformation is,therefore,crucial and can be carried out by several strategies that often require the preparation of sophisticated and/or expensive organic networks,linkers,or compounds.A different approach to the preparation of heterogeneous catalysts for CO_(2)-epoxide coupling is by applying surface science methodologies to graft molecular fragments or single atoms on various supports leading to well-defined active sites.In this context,surface organometallic chemistry(SOMC),along with comparable methodologies,is a valuable approach for the preparation of efficient,single-site Lewis acids and catalysts for the target cycloaddition reaction on metal oxides,whereas,other grafting methodologies,can be applied to prepare analogous catalysts on different kinds of surfaces.Finally,we discuss very recent advances in the application of surface methodologies for the preparation of single atom catalysts as an increasingly relevant approach towards highly active Lewis acids for the cycloaddition of CO_(2) to epoxides.Overall,we show that Lewis acids and catalysts prepared by facile surface methodologies hold significant potential for future application is the synthesis of cyclic carbonates from CO_(2).

Carbon dioxide chemistry towards carbon-neutrality

Startling rise of carbon dioxide concentration in the atmosphere has become a serious concern to scientists and others.Obviously,reduction of CO_(2) will be ideal to save the future world but increasing number of pop-ulation and theirbelongings is the major drawback to imply this.Whilethe Covid-19 pandemic reduced the CO_(2) concentration temporarily in the last two years,but still carbon dioxide concentrations are ata recordhigh.