Electrocatalytic HER Performance of [FeFe]-Hydrogenase Mimics Bearing M-salen Moieties (M=Zn, Ni, Fe, Mn).

The synthesis and characterization of novel compounds (5-8) as mimetics of [FeFe]-hydrogenase, combining two distinct systems capable of participating in hydrogen evolution reactions (HER): the [(μ-adt)Fe(CO)] fragment and M-salen complexes (salen=N,N'-bis(salicylidene)ethylenediamine) (M=Zn, Ni, Fe, Mn), is reported. These complexes were synthesized in high yields via a three-step procedure from N,N'-bis(4-R-salicylidene)ethanediamine) 4 [R=Fe(CO)(μ-SCH)NCOCHO]. Structural analysis through spectroscopic, spectrometric, and computational (DFT) methods confirmed distorted tetrahedral and square-planar geometries for Zn-salen and Ni-salen complexes (5 and 6) respectively, while complexes Fe-salen 7 and Mn-salen 8 exhibit square-based pyramidal structures typical of Fe(III) and Mn(III) high-spin salen-complexes.

A cross-metathesis approach for polymetallic [FeFe]-hydrogenase mimics.

A method has been developed for synthesizing [FeFe]-Hase mimics with diverse structures and properties, employing cross-metathesis of olefins. Vinylmetallocenes (5 and 6) and vinyl half-sandwich complexes (10 and 11) have been used as cross-metathesis partners with [FeFe]-Hase mimics (4, 8, and 9) bearing a double bond in the moiety attached to the ADT-bridge nitrogen. Electrochemical studies of these complexes, encompassing metallocene-type (7a-b, 12a-b, and 13a-b) as well as half-sandwich derivatives (12c and 13c-d), have demonstrated that the introduction of a redox unit has a marginal impact on the reduction potential of these [FeFe]-Hase mimics.

Design of a Multi-Point Kinematic Coupling for a High Precision Telescopic Simultaneous Measurement System.

This paper covers the design of a new multi-point kinematic coupling specially developed for a high precision multi-telescopic arm measurement system for the volumetric verification of machine tools with linear and/or rotary axes. The multipoint kinematic coupling allows the simultaneous operation of the three telescopic arms that are registered at the same time to a sphere fixed on the machine tool spindle nose. Every coupling provides an accurate multi-point contact to the sphere, avoiding collisions and interferences with the other two multi-point kinematic couplings, and generating repulsion forces among them to ensure the coupling's fingers interlacing along the machine tool x/y/z travels in the verification process.

Bronchoscopist's perception of the quality of the single-use bronchoscope (Ambu aScope4™) in selected bronchoscopies: a multicenter study in 21 Spanish pulmonology services.

Background: The disposable bronchoscope is an excellent alternative to face the problem of SARS-CoV-2 and other cross infections, but the bronchoscopist's perception of its quality has not been evaluated.

Methods: To evaluate the quality of the Ambu-aScope4 disposable bronchoscope, we carried out a cross-sectional study in 21 Spanish pulmonology services. We use a standardized questionnaire completed by the bronchoscopists at the end of each bronchoscopy.

Revisiting the photochemical synthesis of [FeFe]-hydrogenase mimics: reaction optimization, mechanistic study and electrochemical behaviour.

The photoreaction of [(μ-S)Fe(CO)] and alkenes or alkynes has been optimized to readily obtain functionalized [FeFe]-hydrogenase mimics. Irradiation under low CO pressure in THF produces the corresponding photo-adducts in good/acceptable (alkenes/alkynes) yields, with retention of the starting olefin stereochemistry. DFT-calculations provide plausible reaction pathways in both, singlet and triplet states.