Synthesis by extrusion: continuous, large-scale preparation of MOFs using little or no solvent

YesGrinding solid reagents under solvent-free or low-solvent conditions (mechanochemistry) is emerging as a general synthetic technique which is an alternative to conventional solvent-intensive methods. However, it is essential to find ways to scale-up this type of synthesis if its promise of cleaner manufacturing is to be realised. Here, we demonstrate the use of twin screw and single screw extruders for the continuous synthesis of various metal complexes, including Ni(salen), Ni(NCS)2(PPh3)2 as well as the commercially important metal organic frameworks (MOFs) Cu3(BTC)2 (HKUST-1), Zn(2-methylimidazolate)2 (ZIF-8, MAF-4) and Al(fumarate)(OH). Notably, Al(fumarate)(OH) has not previously been synthesised mechanochemically. Quantitative conversions occur to give products at kg h−1 rates which, after activation, exhibit surface areas and pore volumes equivalent to those of materials produced by conventional solvent-based methods. Some reactions can be performed either under completely solvent-free conditions whereas others require the addition of small amounts of solvent (typically 3–4 mol equivalents). Continuous neat melt phase synthesis is also successfully demonstrated by both twin screw and single screw extrusion for ZIF-8. The latter technique provided ZIF-8 at 4 kg h−1. The space time yields (STYs) for these methods of up to 144 × 103 kg per m3 per day are orders of magnitude greater than STYs for other methods of making MOFs. Extrusion methods clearly enable scaling of mechanochemical and melt phase synthesis under solvent-free or low-solvent conditions, and may also be applied in synthesis more generally.EPSRC (EP/L019655/1

Hematološke karakteristike telestes metohiensis (steindachner, 1901) sa različitih staništa

Telestes metohiensis (Steindachner, 1901) predstavlja endemičnu vrstu riba područja Istočne Hercegovine, sa specifičnim životnim ciklusom i prilagođenostima da određeni dio godine provodi pod zemljom, a sa pojavom velikih voda izlazi na površinu. Istraživanja fizioloških i ekofizioloških karakteristika ove vrste imaju poseban značaj jer se radi o nedovoljno istraženoj vrsti, pri čemu su podaci ovoga karaktera oskudni i fragmentirani, a radi se o vrsti koja se obuhvaćena Crvenom listom Republike Srpske, dok je dvije najveće baze ovih podataka WCMC i IUCN svrstavaju je u prvu kategoriju ranjivih vrsta. Fiziološka istraživanja endemičnih vrsta riba su od posebnog značaja, jer daju uvid u niz procesa u organizmu, a posredno i u životnoj sredini, što je neophodno pri prilikom planiranja i provođenja mjera zaštite. Hematološki parametri predstavljaju pouzdane indikatore stanja organizma, a posredno i stanja životne sredine. Za utvrđivanje hematološkog statusa koriste se kvantitativni karakteri ćelija crvene i bijele loze, koji pružaju uvid u čitav niz procesa u organizmu, a na osnovu analize različitih komponenti krvi može se suditi o promjenama koje nastaju u određenim sistemima pod uticajem faktora spoljašnje i unutrašnje sredine. Hematološki parametri su obuhvatali: broj eritrocita, koncentraciju hemoglobina, hematokrit, MCV, MCH i MCHC. Praćeni parametri su analizirani kod jedinki gatačke gaovice koje su lovljene u vodotocima: Vrijeka, Opačica i Zalomka. Prve dvije rijeke se nalaze na području Dabarskog polja, dok rijeka Zalomka teče kroz Nevesinjsko polje. Rezultati pokazuju postojanje značajnih razlika u vrijednostima praćenih parametra prilikom komparacije po lokalitetima, pri čemu su jedinke iz rijeke Vrijeke imale veće vrijednosti koncentracije hemoglobina, vrijednost hematokrita, broja eritrocita i srednje vrijednosti količine hemoglobina u eritrocitima (MCH) u odnosu na druga dva vodotoka

Development of solvent-free synthesis of hydrogen-bonded supramolecular polyurethanes

In this work we describe the solvent free synthesis of supramolecular polyurethanes held together by heterocomplementary triple hydrogen bonding. We perform a systematic evaluation on the base catalyzed synthesis of small molecule ureas and carbamates from a range of isocyanates, amines and alcohols in solution and in the solid state using ball milling. These optimized procedures are then shown to be applicable to the synthesis of supramolecular polyurethanes using solvent-free method

Selective CO₂ capture in metal-organic frameworks with azine-functionalized pores generated by mechanosynthesis

Two new three-dimensional porous Zn(II)-based metal-organic frameworks, containing azine-functionalized pores, have been readily and quickly isolated via mechanosynthesis, by using a nonlinear dicarboxylate and linear N-donor ligands. The use of nonfunctionalized and methyl-functionalized N-donor ligands has led to the formation of frameworks with different topologies and metal-ligand connectivities and therefore different pore sizes and accessible volumes. Despite this, both metal-organic frameworks (MOFs) possess comparable BET surface areas and CO₂ uptakes at 273 and 298 K at 1 bar. The network with narrow and interconnected pores in three dimensions shows greater affinity for CO compared to the network with one-dimensional and relatively large pores-attributable to the more effective interactions with the azine groups

MASC 2022: What challenges and opportunities do supramolecular chemists face in coming years?

Supramolecular chemistry has gone from strength to strength in recent decades, with its impact felt from catalysis to materials science to chemical biology. This Voices article, published to coincide with the 2022 Macrocyclic and Supramolecular Chemistry Group meeting at the University of Nottingham, UK, asks speakers from the meeting: what are the major challenges and opportunities facing the field in coming years

Silicon Detector Telescope for proton detection in electron scattering reactions at MAMI

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Kaonic atoms at the DAFNE collider: a strangeness adventure

Kaonic atoms are an extremely efficient tool to investigate the strong interaction at the low energy Frontier, since they provide direct access to the K-N interaction at threshold, eliminating the necessity for extrapolation, unlike in the case of scattering experiments. During the 1970s and 1980s, extensive studies were performed on kaonic atoms spanning across a broad spectrum of elements in the periodic table, ranging from lithium to uranium. These measurements provided inputs and constraints for the theoretical description of the antikaon-nuclei interaction potential. Nevertheless, the existing data suffer from significant experimental uncertainties, and numerous measurements have been found to be inconsistent with more recent measurements that utilize advanced detector technology. Furthermore, there remain numerous transitions of kaonic atoms that have yet to be measured. For these reasons, a new era of kaonic atoms studies is mandatory. The DA & phi;NE electron-positron collider at the INFN Laboratory of Frascati (INFN-LNF) stands out as a unique source of low-energy kaons, having been utilized by Collaborations such as DEAR, SIDDHARTA, and AMADEUS for groundbreaking measurements of kaonic atoms and kaon-nuclei interactions. Presently, the SIDDHARTA-2 experiment is installed at DA & phi;NE, aiming to perform the first-ever measurement of the 2p & RARR; 1s x-ray transition in kaonic deuterium, a crucial step towards determining the isospin-dependent antikaon-nucleon scattering lengths. Based on the experience gained with the SIDDHARTA experiment, which performed the most precise measurement of the kaonic hydrogen 2p & RARR; 1s x-ray transition, the SIDDHARTA-2 setup is now fully equipped for the challenging kaonic deuterium measurement. In this paper, we present a comprehensive description of the SIDDHARTA-2 setup and of the first kaonic atoms measurements performed during the commissioning phase of the DA & phi;NE collider. We also outline a proposal for future measurements of kaonic atoms at DA & phi;NE beyond SIDDHARTA-2, which is intended to stimulate discussions within the broad scientific community performing research, directly or indirectly, related to this field