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A new nanodevice based on gold nanoparticles (AuNPs) capped with poly(diethylvinylphosphonate) (PDEVP) has been synthesized, showing interesting photophysical and thermoresponsive properties. The synthesis involves a properly designed Yttriocene catalyst coordinating the vinyl-lutidine (VL) initiator active in diethyl vinyl phosphonate polymerization. The unsaturated PDEVP chain ending was thioacetylated, deacetylated, and reacted with tetrachloroauric acid and sodium borohydride to form PDEVP-VL-capped AuNPs. The NMR, UV–Vis, and ESI-MS characterization of the metal nanoparticles confirmed the formation of the synthetic intermediates and the expected colloidal systems. AuNPs of subnanometric size were determined by WAXD and UV–Vis analysis. UV–Vis and fluorescence analysis confirmed the effective anchoring of the thiolated PDEVP to AuNPs. The formation of 50–200 nm globular structures was assessed by SEM and AFM microscopy in solid state and confirmed by DLS in aqueous dispersion. Hydrodynamic radius studies showed colloidal contraction with temperature, demonstrating thermoresponsive behavior. These properties suggest potential biomedical applications for the photoablation of malignant cells or controlled drug delivery induced by light or heat for the novel PDEVP-capped AuNP systems. [ABSTRACT FROM AUTHOR]

Carbon dioxide utilization is considered an effective strategy to mitigate the carbon footprint of chemical industry. Among other uses, the incorporation of carbon dioxide into cyclic organic carbonates (COCs) and aliphatic polycarbonates (APCs) has received great attention in the field of homogeneous catalysis. After few decades of research activity, a wide range of metal‐based catalytic systems has been reported to promote this reaction. Nonetheless, a better comprehension of the apparently simple reaction mechanism of such transformations has been reached only in recent years. This, in turn, allowed for the design of new catalytic systems guided by a clearer mechanistic picture. In this review, we present the most recent advancements in this field, distinguishing between catalysts for COCs and APCs production classified on the bases of their ligand structures. [ABSTRACT FROM AUTHOR]

Synthetic polymers have a key role in modern society as they have allowed for great technological advancement since their discovery. However, the use of fossil-fuel-based raw materials and the pollution derived from plastics accumulation in the environment raised enormous concern, driving research efforts toward the identification of more sustainable alternatives. Bio-based functional molecules susceptible to ring-opening (co)polymerisation [RO(C)OP], such as lactones, cyclic carbonates, and oxiranes, represent an attractive source of monomers for the synthesis of more sustainable polymers. In this review, we describe the main advancement in this research field reported during the last seven years. In particular, we describe the preparation of monomers from (renewable) bio-sources such as sugars, terpenes, fatty acids, and carbon dioxide with a focus on structurally novel substrates. Both metal-mediated and organo-catalytic RO(CO)P methods are described, and the properties of derived functional polymers are discussed when relevant. [ABSTRACT FROM AUTHOR]

The unparalleled potential of substrate‐induced reactivity modes in the catalytic conversion of carbon dioxide and alcohol or amine functionalized epoxides is discussed in relation to more conventional epoxide/CO2 coupling strategies. This conceptually new approach allows for a substantial extension of the substitution degree and functionality of cyclic carbonate/carbamate products, which are predominant products in the area of nonreductive CO2 transformations. Apart from the creation of an advanced library of CO2‐based heterocyclic products and intermediates, also the underlying mechanistic reasons for this novel reactivity profile are debated with a prominent role for the design and structure of the involved catalysts. [ABSTRACT FROM AUTHOR]

The efficient formation of cyclic polyesters from the ring‐opening polymerization of lactide, ϵ‐caprolactone, and β‐butyrolactone catalyzed by a 1,4‐dithiabutanedyl‐2,2′‐bis(4,6‐dicumylphenol) [OSSO]‐FeCl complex activated with cyclohexene oxide was achieved. The catalyst was very active (initial turnover frequency up to 2718 h−1), robust, and worked with a monomer/Fe ratio up to 10 000. The formation of cyclic polymers was supported by using high‐resolution matrix‐assisted laser desorption ionization (MALDI) MS, and the average ring size (≈5 kDa for cyclic polylactide) independent of the reaction conditions. A monometallic ring‐opening polymerization/cyclization mechanism was proposed from the results of a kinetic investigation. [ABSTRACT FROM AUTHOR]

Among the attempts to consolidate the so‐called circular economy, the conversion of carbon dioxide (CO2) into added‐value products has gained more and more attention during the last three decades. One of the feasible applications of CO2 as a C1 building block is its incorporation into cyclic organic carbonates (COCs) and aliphatic polycarbonates (APCs) by reaction with epoxides. A plethora of homogeneous catalytic systems has been reported to promote this reaction, based mainly on magnesium, aluminium, cobalt, chromium and zinc complexes. Despite the abundance and low toxicity of iron, only few examples of catalysts based on this metal had been reported until fifteen years ago, and relevant advances were made only during the last decade. This review seeks to cover this progress and to give a renewed impulse for further research into iron utilisation in this kind of catalysis. [ABSTRACT FROM AUTHOR]

A new [OSSO]‐Fe(III) metallate complex was prepared and characterized. We demonstrated that such metallate is the real catalytic active species for the cycloaddition of CO2 to the epoxides, formed from the in situ reaction of the related [OSSO]‐Fe(III) neutral complexes and tetrabutylammonium bromide. The metallate complex was used as a single component catalyst for the formation of cyclic organic carbonates from ten epoxides and CO2 at 1 bar pressure with good activity. [ABSTRACT FROM AUTHOR]

Glycidol is converted into glycerol carbonate (GC) by coupling with CO2 in the presence of tetrabutylammonium bromide (TBAB) under mild reaction conditions ( T=60 °C, P [ABSTRACT FROM AUTHOR]

A series of group 4 metal complexes 1–4(1 = (t-BuOS)2Ti(O-i-Pr)2; 2= (t-BuOS)2Zr(O-t-Bu)2; 3=(t-BuOS)2Hf(O-t-Bu)2; 4= (CumOS)2Zr(O-t-Bu)2) supported by twophenolate bidentate ligands (t-BuOS–H = 4,6-di-tert-butyl-2-phenylsulfanylphenoland CumOS–H = 4,6-dicumyl-2-phenylsulfanylphenol)were synthesized by the reaction of appropriate metal tetra(alkoxide)swith 2 equiv of the ligands. The X-ray structure of 2revealed that the two ligands were κ2-chelatedto the metal center with two phenoxy groups in trans positions andthe two thioether moieties in cis positions. VT NMR analysis revealeda fast inversion of configuration at the metal center. Complexes 1–4promoted the ring-opening polymerization(ROP) of lactide and ε-caprolactone. Complex 4exhibitedthe highest activity with a pseudo-first-order rate constant of 0.061± 0.003 min–1at 100 °C, which comparesfavorably with those reported for the most active group 4 complexes.Polymerizations were well-controlled, giving predictable molecularweights and narrow molecular weight distributions. Essentially atacticPLA were obtained in the ROP of rac-lactide. A DFTstudy on ROP promoted by these complexes highlighted the importanceof the coordinative flexibility of the ancillary ligand to promotemonomer coordination at the reactive metal center. In presence ofisopropanol, lower PDI indexes and molecular weights of the PLAs proportionalto the equivalents of isopropanol suggested that adequate conditionsfor effective “immortal” polymerizationswere achieved. More interestingly, these catalysts promoted the copolymerizationof l-lactide and ε-caprolactone. The microstructuredisclosed by 13C NMR analysis and the thermal behaviorexhibited in DSC studies indicated a random distribution of the twomonomer along the polymer chain. [ABSTRACT FROM AUTHOR]

Glycidol is converted into glycerol carbonate (GC) by coupling with CO 2 in the presence of tetrabutylammonium bromide (TBAB) under mild reaction conditions (T=60 °C, PCO2 =1 MPa) in excellent yields (99 %) and short reaction time (t=3 h). The unusual reactivity of this substrate compared to other epoxides, such as propylene oxide, under the same reaction conditions is clearly related to the presence of a hydroxyl functionality on the oxirane ring. Density functional theory calculations (DFT) supported by 1 H NMR experiments reveal that the unique behavior of this substrate is a result of the formation of intermolecular hydrogen bonds into a dimeric structure, activating this molecule to nucleophilic attack, and allowing the formation of GC. Furthermore, the glycidol/TBAB catalytic system acts as an efficient organocatalyst for the cycloaddition of CO 2 to various oxiranes., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)