Micrometre‐sized porous polymer beads as heterogeneous molecular catalysts

Porous polymers have great potential as versatile, chemically stable catalyst supports. Yet, shaping of the resulting powders remains a challenge. Here, we demonstrate the use of suspension polymerisation to design micrometre-sized porous polymers beads containing metal binding sites. The good accessibility of the binding sites ensures high catalytic activity, which is demonstrated for two model reactions: photochemical CO2 reduction and transfer hydrogenation of aromatic ketones. Importantly, the shaping of the host material does not affect the catalytic activity of the active site

Pyrene‐ and Bipyridine‐based Covalent Triazine Framework as Versatile Platform for Photocatalytic Solar Fuels Production**

The ability to molecularly engineer materials is a powerful tool toward increasingly performing heterogeneous catalysts. Porous organic polymers stand out as photocatalysts due to their high chemical stability, outstanding optoelectronic properties and their easy and tunable syntheses. In photocatalysis, the insertion of photosensitizing π‐extended molecules into molecularly well‐defined donor‐acceptor junctions is supposed to increase the catalytic activity, but yet remain experimentally underdeveloped. This study presents a pyrene‐based Covalent Triazine Framework (CTF) synthesized through a polycondensation approach, which was designed to contain a molecularly‐defined pyrene‐triazine‐bipyridine donor‐acceptor‐acceptor triad as the repetition unit of the CTF. The CTF is an efficient photocatalyst for hydrogen evolution from water reaching a significant production rate of 61.5 mmolH2/h/gcat. Moreover, the same CTF can easily be used as porous macroligand for an organometallic Rh complex to efficiently catalyze the carbon dioxide photoreduction into formic acid under visible light.Covalent Triazine Frameworks for enhanced photocatalysis: Pyrene‐triazine‐bipyridine donor‐acceptor‐acceptor triad CTF enables highly efficient photocatalytic hydrogen evolution from water with a production rate of 61.5 mmol/h/gcat. Functionalization of the CTF with an organometallic rhodium complex allows for photocatalytic carbon dioxide reduction into formic acid with a rate of 130 μmol/h/gcat. image SINCHEMFuel Science CentreGerman Federal Environmental Foundation http://dx.doi.org/10.13039/10000763

Reusable Copper Catechol‐based Porous Polymers for the Highly Efficient Heterogeneous Catalytic Oxidation of Secondary Alcohols

New catechol-based porous polymers were synthesized and used as platforms for the heterogenization of molecular Cu complexes. The resulting Cu@CatMP-1 materials proved to be highly stable and performing catalysts for the oxidation of secondary alcohols with turnover numbers up to 6000, about 1 to 2 orders of magnitude higher than the current relevant state of the art, using catalyst loadings as low as 25 ppm of Cu. The solid catalyst proved to be recyclable for over 10 runs without detectable metal leaching and has been scaled to the gram scale. The coordination of Cu to catechol within the polymer has been evidenced by X-ray absorption spectroscopy

Satellite and in situ observations for advancing global Earth surface modelling: a review

In this paper, we review the use of satellite-based remote sensing in combination with in situ data to inform Earth surface modelling. This involves verification and optimization methods that can handle both random and systematic errors and result in effective model improvement for both surface monitoring and prediction applications. The reasons for diverse remote sensing data and products include (i) their complementary areal and temporal coverage, (ii) their diverse and covariant information content, and (iii) their ability to complement in situ observations, which are often sparse and only locally representative. To improve our understanding of the complex behavior of the Earth system at the surface and sub-surface, we need large volumes of data from high-resolution modelling and remote sensing, since the Earth surface exhibits a high degree of heterogeneity and discontinuities in space and time. The spatial and temporal variability of the biosphere, hydrosphere, cryosphere and anthroposphere calls for an increased use of Earth observation (EO) data attaining volumes previously considered prohibitive. We review data availability and discuss recent examples where satellite remote sensing is used to infer observable surface quantities directly or indirectly, with particular emphasis on key parameters necessary for weather and climate prediction. Coordinated high-resolution remote-sensing and modelling/assimilation capabilities for the Earth surface are required to support an international application-focused effort

An analog of the Fefferman construction

summary:The Fefferman construction associates to a manifold carrying a CR–structure a conformal structure on a sphere bundle over the manifold. There are some analogs to this construction, with one giving a Lie contact structure, a refinement of the contact bundle on the bundle of rays in the cotangent bundle of a manifold with a conformal metric. Since these structures are parabolic geometries, these constructions can be dealt with in this setting

Des solides poreux comme macroligands solides pour un lien entre catalyse homogène et hétérogène

International audienceThe integration of catalytically active centers into a solid support without loss of performance compared to their homogeneous analogs is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. Porous solids such as Metal-Organic Frameworks (MOF) and purely organic Porous Organic Polymers (POP) are appealing candidates. Using a series of heterogeneous catalysts based on MOF and POP as macroligands of organometallic complexes, we show that both homogeneous and heterogenized catalysts follow the same linear correlation between the electronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. The rational design of novel heterogeneous catalysts can thus be guided by rules from molecular chemistry.L'intégration de centres catalytiquement actifs sur un support solide sans perte de performance par rapport à la version en solution reste un défi majeur. Dans ce contexte, un support défini au niveau moléculaire en tant que macroligand, c'est-à-dire un solide agissant comme le ligand dans le complexe moléculaire correspondant, permet de créer un lien entre la catalyse homogène et hétérogène. Les solides poreux tels que les Metal-Organic Frameworks (MOF) et Polymères Organiques Poreux (POP) sont des candidats prometteurs. En utilisant une série de catalyseurs hétérogènes à base de MOF et de POP en tant que macroligands pour des complexes organométalliques hétérogénéisés, nous montrons que les catalyseurs homogènes et hétérogènes suivent la même corrélation linéaire entre l'effet électronique du ligand, décrit par la constante de Hammett, et l'activité catalytique. La conception rationnelle de nouveaux catalyseurs hétérogènes peut donc être guidée par des règles de la chimie moléculaire

Des solides poreux comme macroligands solides pour un lien entre catalyse homogène et hétérogène

International audienceThe integration of catalytically active centers into a solid support without loss of performance compared to their homogeneous analogs is still a major challenge. In this context, a molecularly defined support as macroligand, i.e. a solid acting like the ligand in the corresponding molecular complex, can be considered as a key to bridge the gap between molecular and heterogeneous catalysis. Porous solids such as Metal-Organic Frameworks (MOF) and purely organic Porous Organic Polymers (POP) are appealing candidates. Using a series of heterogeneous catalysts based on MOF and POP as macroligands of organometallic complexes, we show that both homogeneous and heterogenized catalysts follow the same linear correlation between the electronic effect of the ligand, described by the Hammett parameter, and the catalytic activity. The rational design of novel heterogeneous catalysts can thus be guided by rules from molecular chemistry.L'intégration de centres catalytiquement actifs sur un support solide sans perte de performance par rapport à la version en solution reste un défi majeur. Dans ce contexte, un support défini au niveau moléculaire en tant que macroligand, c'est-à-dire un solide agissant comme le ligand dans le complexe moléculaire correspondant, permet de créer un lien entre la catalyse homogène et hétérogène. Les solides poreux tels que les Metal-Organic Frameworks (MOF) et Polymères Organiques Poreux (POP) sont des candidats prometteurs. En utilisant une série de catalyseurs hétérogènes à base de MOF et de POP en tant que macroligands pour des complexes organométalliques hétérogénéisés, nous montrons que les catalyseurs homogènes et hétérogènes suivent la même corrélation linéaire entre l'effet électronique du ligand, décrit par la constante de Hammett, et l'activité catalytique. La conception rationnelle de nouveaux catalyseurs hétérogènes peut donc être guidée par des règles de la chimie moléculaire

Comparison of Current Swiss Fetal Biometry Reference Charts with Reference Charts from 1999. Are Fetuses Getting Bigger?

PURPOSE:  To create current fetal biometry reference ranges and to compare them with references published in 1999, from the same local area in order to generate data for secular trend in fetal size. MATERIALS AND METHODS:  Applying the same methodology as previously published, we calculated reference ranges for biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC) and femur length (FL) in 7863 patients examined at the obstetric clinics in a cross-sectional, prospective study in a university setting from January 2008 to December 2014. In order to compare the new reference ranges with our previously published data, we used Z-Scores and displayed the pick-up of fetal biometry data below the 5th and above the 95th percentile using the previously published reference charts. RESULTS:  The comparison of the charts showed a minimal but clinically relevant increase in mean fetal body measures (BPD, HC, AC). Applying the 1999 charts to the new dataset, we would classify only 162 of 339 fetuses (47.8 %) to be correctly below the 5th percentile for AC and only 134 of 349 (38.4 %) fetuses were correctly below the 5th percentile for HC. On the other hand, the 1999 charts classified 426 instead of 332 fetuses to be above the 95th percentile for AC, which means an overestimation of 28.3 %. CONCLUSION:  Applying a similar methodology, study collective and clinical setting, our new charts showed clinically relevant differences compared to the 1999 charts. The data suggest that within one generation fetuses are getting bigger and regular updates of fetal reference charts are needed

If MOFs could talk

SSCI-VIDE+ING+JEC:FWI:DFAInternational audienceIn the rush to innovation in Metal-Organic Frameworks, new methodologies have emerged in order to characterize ever more sophisticated materials that embed sometimes several different functional groups (chiral, organometallics, luminescent,…) in a single crystalline structure.Cutting-edge spectroscopic techniques, even combined with DFT calculations, have been successfully applied to the characterization of MOF materials containing multiple functionalities gathered in a unique framework.[1]Since the early 1980s, photoacoustic Fourier transform infrared spectroscopy (PA FT-IR) has been the subject of numerous technological evolutions, especially in sound collection.[2] Beyond its application in biomedical imaging, this technique has already been used to analyze inorganic rough surfaces and gases.[3]Here we present for the first time the correlation between the sound produced by IR-illuminated MOFs and the organic composition of their mixed-linker frameworks. We recently reported the use of azido-to-amino turn-on luminescence of a MOF upon sulfide exposure for the sensing of H2S as biomarker in physiological media.[4] The amino content in the amino/azido-MOF, after exposure of the pure azido, was directly linked to the sulfide concentration, used as biomarker for non-communicable diseases, of the analyzed biological sample solution. Similarly, we explore herein the different photoacoustic response of MOF-N3 and MOF-NH2, in order to ultimately determine the N3-to-NH2 molecular ratio in mixed-linker MOF powders.Furthermore, the sensitivity determined for the detection of amino content in an azido-MOF matrix is two orders of magnitude higher using PA FT-IR than using classic IR spectroscopy. The first sound collection from IR-illuminated mixed-linker MOFs allows determining their organic composition (i) in the solid state, (ii) rapidly and (iii) without specific sample preparation with outstanding sensitivity. This opens appealing new perspectives for the rapid characterization of libraries of multifunctional hybrid materials as well as for the use of MOFs in compact sensing devices.[1] Rossini et al. Angew. Chem. Int. Ed. 2012, 51, 123; Todorova et al. Chem. Eur. J. 2016, 22, 16531; Kong et al. Science 2013, 341, 882; Katzenmeyer et al. Angew. Chem. Int. Ed. 2014, 53, 2852.[2] Kuusela et al. Appl. Spectrosc. Rev. 2007, 42, 443[3] Wang et al. Nat. Photon. 2009, 3, 503 ; Wang et al. Nat. Methods 2016, 13, 627; Michaelian, K. H. Photoacoustic IR Spectroscopy: Instrumentation, Applications and Data Analysis, 2nd, Revised and Enlarged Edition; Wiley-VCH, 2010[4] Legrand et al. ChemNanoMat 2016, 2, 866-872