New class of hybrid materials for detection, capture, and "on-demand" release of carbon monoxide

YesCarbon monoxide (CO) is both a substance hazardous to health and a side product of a number of industrial processes, such as methanol steam reforming and large-scale oxidation reactions. The separation of CO from nitrogen (N2) in industrial processes is considered to be difficult because of the similarities of their electronic structures, sizes, and physicochemical properties (e.g., boiling points). Carbon monoxide is also a major poison in fuel cells because of its adsorption onto the active sites of the catalysts. It is therefore of the utmost economic importance to discover new materials that enable effective CO capture and release under mild conditions. However, methods to specifically absorb and easily release CO in the presence of contaminants, such as water, nitrogen, carbon dioxide, and oxygen, at ambient temperature are not available. Here, we report the simple and versatile fabrication of a new class of hybrid materials that allows capture and release of carbon monoxide under mild conditions. We found that carborane-containing metal complexes encapsulated in networks made of poly(dimethylsiloxane) react with CO, even when immersed in water, leading to dramatic color and infrared signature changes. Furthermore, we found that the CO can be easily released from the materials by simply dipping the networks into an organic solvent for less than 1 min, at ambient temperature and pressure, which not only offers a straightforward recycling method, but also a new method for the “on-demand” release of carbon monoxide. We illustrated the utilization of the on-demand release of CO from the networks by carrying out a carbonylation reaction on an electron-deficient metal complex that led to the formation of the CO-adduct, with concomitant recycling of the gel. We anticipate that our sponge-like materials and scalable methodology will open up new avenues for the storage, transport, and controlled release of CO, the silent killer and a major industrial poison.The Royal Society, The Romanian Ministry of Education and Research, The University of Bradford, European Regional Development Fund of the European UnionResearch Development Fund Publication Prize Award winner

Synthesis and controlled growth of osmium nanoparticles by electron irradiation

YesWe have synthesised osmium nanoparticles of defined size (1.5–50 nm) on a B- and S-doped turbostratic graphitic structure by electron-beam irradiation of an organometallic osmium complex encapsulated in self-spreading polymer micelles, and characterised them by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and atomic force microscopy (AFM) on the same grid. Oxidation of the osmium nanoparticles after exposure to air was detected by X-ray photoelectron spectroscopy (XPS).We thank the Leverhulme Trust (Early Career Fellowship No. ECF-2013-414 to NPEB), the University of Warwick (Grant No. RD14102 to NPEB), the ERC (Grant No. 247450 to PJS), and the EPSRC (EP/F034210/1 to PJS). L.M.A.P., J.L., and G.C. acknowledge financial support from the EU through the ERC Consolidator Grant “VISUAL-MS”

Pseudo electron-deficient organometallics: limited reactivity towards electron-donating ligands

YesHalf-sandwich metal complexes are of considerable interest in medicine, material, and nanomaterial chemistry. The design of libraries of such complexes with particular reactivity and properties is therefore a major quest. Here, we report the unique and peculiar reactivity of eight apparently 16-electron half-sandwich metal (ruthenium, osmium, rhodium, and iridium) complexes based on benzene-1,2-dithiolato and 3,6-dichlorobenzene-1,2-dithiolato chelating ligands. These electron-deficient complexes do not react with electron-donor pyridine derivatives, even with the strong σ-donor 4-dimethylaminopyridine (DMAP) ligand. The Ru, Rh, and Ir complexes accept electrons from the triphenylphosphine ligand (σ-donor, π-acceptor), whilst the Os complexes were found to be the first examples of non-electron-acceptor electron-deficient metal complexes. We rationalized these unique properties by a combination of experimental techniques and DFT/TDFT calculations. The synthetic versatility offered by this family of complexes, the low reactivity at the metal center, and the facile functionalization of the non-innocent benzene ligands is expected to allow the synthesis of libraries of pseudo electron-deficient half-sandwich complexes with unusual properties for a large range of applications

Retaining individualities: the photodynamics of self-ordering porphyrin assemblies

The retention of photochemical properties of individual chromophores is a key feature of biological light harvesting complexes. This is achieved despite extensive aggregation of the chromophores, which in synthetic chromophore assemblies often yields a change in spectral characteristics. As an alternative approach towards mimicking biological light harvesting complexes, we report the synthesis of porphyrin assemblies which retained the photochemical properties of the individual chromophore units despite their substantial aggregation. These new materials highlight a new bottom-up approach towards the design and understanding of more complex biomimetic and naturally occurring biological systems

Preclinical Anticancer Activity of an Electron-Deficient Organoruthenium(II) Complex

YesRuthenium compounds have been shown to be promising alternatives to platinum(II) drugs. However, their clinical success depends on achieving mechanisms of action that overcome Pt-resistance mechanisms. Electron-deficient organoruthenium complexes are an understudied class of compounds that exhibit unusual reactivity in solution and might offer novel anticancer mechanisms of action. Here, we evaluate the in vitro and in vivo anticancer properties of the electron-deficient organoruthenium complex [(p-cymene)Ru(maleonitriledithiolate)]. This compound is found to be highly cytotoxic: 5 to 60 times more potent than cisplatin towards ovarian (A2780 and A2780cisR), colon (HCT116 p53+/+ and HCT116 p53−/−), and non-small cell lung H460 cancer cell lines. It shows no cross-resistance and is equally cytotoxic to both A2780 and A2780cisR cell lines. Furthermore, unlike cisplatin, the remarkable in vitro antiproliferative activity of this compound appears to be p53-independent. In vivo evaluation in the hollow-fibre assay across a panel of cancer cell types and subcutaneous H460 non-small cell lung cancer xenograft model hints at the activity of the complex. Although the impressive in vitro data are not fully corroborated by the in vivo follow-up, this work is the first preclinical study of electron-deficient half-sandwich complexes and highlights their promise as anticancer drug candidates.UF150295/Royal Society; University of Bradford; Government Department of Business, Energy and Industrial Strategy; SBF003\1170/British Heart Foundation Springboard Award; AMS_/Academy of Medical Sciences/United Kingdo

The sound of chemistry: Translating infrared wavenumbers into musical notes

YesThe abstract nature of physical chemistry and spectroscopy makes the subject difficult to comprehend for many students. However, bridging arts and science has the potential to provide innovative learning methods and to facilitate the understanding of abstract concepts. Herein, we present a high-school project based on the conversion of selected infrared absorbances of well-known molecules into audible frequencies. This process offered students a unique insight into the way molecules and chemical bonds vibrate, as well as an opportunity to develop their creativity by producing musical pieces related to the molecules they synthesized. We believe that experiencing chemistry from an alternative viewpoint opens up new perspectives not only for student learning but also for the decompartmentalization of scientific and artistic disciplines.This project was supported by the Royal Society (Partnership Grant no. PG\170122 to NPEB and NG and University Research Fellowship no. UF150295 to NPEB) and the Academy of Medical Sciences/the Wellcome Trust/the Government Department of Business, Energy and Industrial Strategy/the British Heart Foundation springboard Award [SBF003\1170 to NPEB]

Structural reorganization of cylindrical nanoparticles triggered by polylactide stereocomplexation

YesCo-crystallization of polymers with different configurations/tacticities provides access to materials with enhanced performance. The stereocomplexation of isotactic poly(L-lactide) and poly(D-lactide) has led to improved properties compared with each homochiral material. Herein, we report the preparation of stereocomplex micelles from a mixture of poly(L-lactide)-b-poly(acrylic acid) and poly(D-lactide)-b-poly(acrylic acid) diblock copolymers in water via crystallization-driven self-assembly. During the formation of these stereocomplex micelles, an unexpected morphological transition results in the formation of dense crystalline spherical micelles rather than cylinders. Furthermore, mixture of cylinders with opposite homochirality in either THF/H2O mixtures or in pure water at 65 °C leads to disassembly into stereocomplexed spherical micelles. Similarly, a transition is also observed in a related PEO-b-PLLA/PEO-b-PDLA system, demonstrating wider applicability. This new mechanism for morphological reorganization, through competitive crystallization and stereocomplexation and without the requirement for an external stimulus, allows for new opportunities in controlled release and delivery applications.University of Warwick, Swiss National Science Foundation and the EPSRC. The Royal Society - an Industry Fellowship to A.P.D. The Engineering and Physical Sciences Research Council (EP/G004897/1) - funding to support postdoctoral fellowships for A.P.B. as well as funding for J.S. and M.A.D. through the Warwick Centre for Analytical Science (EP/F034210/1). The Science City Research Alliance and the HEFCE Strategic Development Fund - funding support. Some items of equipment that were used in this research were funded by Birmingham Science City, with support from Advantage West Midlands and part-funded by the European Regional Development Fund

Separation and purification of curcumin using novel aqueous two-phase micellar systems composed of amphiphilic copolymer and cholinium ionic liquids

Novel aqueous two-phase micellar systems (ATPMS) composed of Pluronic F68, a triblock amphiphilic copolymer, and cholinium-based ionic liquids (ILs) were formulated and applied for separation/purification of curcumin (CCM). CCM stability in the presence of ATPMS components was also evaluated. CCM is stable up to 24 h in copolymer (1.0 10.0 wt%) and ILs (0.1 3.0 M) aqueous solutions. Very mild phase separation conditions (close to room temperature) were achieved by adding cholinium ILs to the Pluronic F68 + McIlvaine buffer at pH 6.0 solution. The decrease of cloud-point temperature is dependent on the relative hydrophobicity of IL anion, [Hex] > [But] > [Prop] > [Ac] > Cl. ATPMS composed of more hydrophobic ILs ([Ch][Hex] > [Ch][But] > [Ch][Prop]) are most efficient in the partition of commercial CCM into polymeric micelles-rich phase. The best ATPMS (0.70 M [Ch][But] and 0.60 M [Ch][Hex]-based ATPMS) were then used to purify CCM from a crude extract of Curcuma longa L. Both systems were very selective to separate CCM from protein-based contaminants (selectivity values 25; purification yields 12-fold). Pluronic F68-based ATPMS are promising for selective separation of hydrophobic biomolecules by using cholinium-based ILs as adjuvants to adjust phase separation temperatures and biomolecules partition.This study was funded by the Coordination for Higher Level Graduate Improvements (CAPES/Brazil, finance code 001), National Council for Scientific and Technological Development (CNPq/Brazil) and the State of São Paulo Research Foundation (FAPESP/Brazil, processes #2014/16424-7, #2017/10789-1, #2018/10799-0, #2018/05111-9; #2019/05624-9, and #2019/08549-8). A.M. Lopes and J.F.B. Pereira are grateful for the language revision of native speaker H.S. Pacheco Neto.info:eu-repo/semantics/publishedVersio

Retaining individualities : the photodynamics of self-ordering porphyrin assemblies

YesThe retention of photochemical properties of individual chromophores is a key feature of biological light harvesting complexes. This is achieved despite extensive aggregation of the chromophores, which in synthetic chromophore assemblies often yields a change in spectral characteristics. As an alternative approach towards mimicking biological light harvesting complexes, we report the synthesis of porphyrin assemblies which retained the photochemical properties of the individual chromophore units despite their substantial aggregation. These new materials highlight a new bottom-up approach towards the design and understanding of more complex biomimetic and naturally occurring biological systems.Seventh Framework Programme (European Commission) (FP7), Engineering and Physical Sciences Research Council (EPSRC), Royal Society (Great Britain

Dominance Invariant Roommate Problems

The synthesis of cyclic amphiphilic graft copolymers with a hydrophobic polycarbonate backbone and hydrophilic poly­(<i>N</i>-acryloyl­morpholine) (PNAM) side arms via a combination of ring-opening polymerization (ROP), cyclization via copper-catalyzed azide–alkyne cycloaddition (CuAAC), and reversible addition–fragmentation chain transfer (RAFT) polymerization is reported. The ability of these cyclic graft copolymers to form unimolecular micelles in water is explored using a combination of light scattering, small-angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryoTEM) analyses, where particle size was found to increase with increasing PNAM arm length. Further analysis revealed differences in the solution conformations, loading capabilities, and morphologies of the cyclic graft copolymers in comparison to equivalent linear graft copolymer unimolecular micelle analogues. Furthermore, the cyclic and linear graft copolymers were found to exhibit significantly different cloud point temperatures. This study highlights how subtle changes in polymer architecture (linear graft copolymer versus cyclic graft copolymer) can dramatically influence a polymer’s nanostructure and its properties