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Atomic scale studies of the anchoring of catalytically active complexes to surfaces may provide valuable insights for the design of new catalytically active hybrid systems. In this work, the self-assembly of 1D, 2D and 3D structures of the complex fac-Re(bpy)(CO)3Cl (bpy = 2,2′-bipyridine), a CO2 reduction catalyst, on the Ag(001) surface are studied by a combination of low-temperature scanning tunneling microscopy and density functional theory calculations. Infrared and sum frequency generation spectroscopy confirm that the complex remains chemically intact under sublimation. Deposition of the complexes onto the silver surface at 300 K leads to strong local variations in the resulting surface coverage on the nanometer scale, indicating that in the initial phase of deposition a large fraction of the molecules is desorbing from the surface. Low coverage regions show a decoration of step edges aligned along the crystal's symmetry axes <110>. These crystallographic directions are found to be of major importance to the binding of the complexes to the surface. Moreover, the interaction between the molecules and the substrate promotes the restructuring of surface steps along these directions. Well-aligned and decorated steps are found to act as nucleation point for monolayer growth (2D) before 3D growth starts. Catalytically active complexes adsorbed to noble metal surfaces hold potential for CO2 utilisation. Here, the mechanism of growth of fac-Re(bpy)(CO)3Cl on Ag(001) is shown to begin at well-oriented surface steps, with surface restructuring promoting the growth of long-range ordered assemblies. [ABSTRACT FROM AUTHOR]

A dinculear Re(CO)3 complex with a proton responsive phenol unit and a pyrene anchor in the ligand backbone was investigated in the electrochemical CO2/H+ conversion in solution and adsorbed on multi walled carbon nanotubes (MWCNT) on an GC electrode surface. The pyrene group unit is introduced at the end of the ligand synthesis via a coupling reaction, which allows for a versatile ligand modification in order to tune the electronic properties or to introduce various anchor groups for heterogenisation at a late stage. The redox chemistry of the pyrene-α-diimine-Re(CO)3 complex, 1, was investigated in N,N-dimethylformamide (dmf), including IR-spectroelectrochemical (IR-SEC) characterisation of the short lived, reduced species. Subsequently, the electrochemical H+/CO2-reduction catalysis in dmf/water was investigated. The complex catalyses syngas formation yielding CO and H2 with similar rates, namely in Faraday yields of 45% and 35%, respectively. Since the similar complex without the pyrene anchor in the backbone, I, prefers CO2 over H+ reduction, the formation of syngas was rationalised by the small differences in the redox properties and pKa values of the phenol-pyrene unit in regard to phenol unit as in I. Subsequently, the complex was adsorbed on multi walled carbon nanotubes (MWCNT) on a GC electrode surface. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirmed coating of the electrode. The immobilised complex was utilised in the electrochemical CO2/H+ reduction in dmf/water, however, the complex quickly desorbed under reductive conditions, likely due to the good solubility of the reduced species. Water as a solvent prevents desorption as confirmed by XPS, however, then a preference for H2 formation over syngas formation was observed under electrocatalytic conditions. Thus, these experiments show, that the results obtained in aqueous organic solution are not easily transferable to the heterogeneous systems operating in water due to changes in the reaction rates for competing pathways. [ABSTRACT FROM AUTHOR]

Psilocybin is an indole-based secondary metabolite found naturally in mushrooms which possesses several pharmacological effects. Recently, a large number of experimental investigations have been conducted to characterize the pharmacology of psilocybin and its derivatives, and to develop synthetic pathways to manufacture psilocybin. Nonetheless, current research on the physical characterization of psilocybin is limited in part due to legal restrictions. In the present study, we investigate two unique tautomers of psilocybin as depicted in the 2D chemical structure of psilocybin presented in the recent literature. Using a combination of electronic structure calculations and molecular simulation, we are able to identify and characterize the thermodynamically preferred tautomer. We additionally computed the solvation free energy and investigated the solvation structure of psilocybin in water and 35 organic solvents. We find that hydrogen bonding between psilocybin and the solvent dominates the solvation process. Considering the thermodynamically preferred tautomer, we find that the solubility in water is greater than all of the studied organic solvents. • Identified zwitterionic psilocybin as the thermodynamically preferred form from the recent literature. • Characterized the molecular and solvation structure of psilocybin. • Predicted the relative solubility (solvation free energy) of psilocybin in water and 35 organic solvents. • Use of anti-solvent crystallization promising for purification of zwitterionic psilocybin. [ABSTRACT FROM AUTHOR]

Modifications of complexes by attachment of anchor groups are widely used to control molecule-surface interactions. This is of importance for the fabrication of (catalytically active) hybrid systems, viz. of surface immobilized molecular catalysts. In this study, the complex fac-Re(S-Sbpy)(CO)3Cl (S-Sbpy = 3,3′-disulfide-2,2′-bipyridine), a sulfurated derivative of the prominent Re(bpy)(CO)3Cl class of CO2 reduction catalysts, was deposited onto the clean Ag(001) surface at room temperature. The complex is thermostable upon sublimation as supported by infrared absorption and nuclear magnetic resonance spectroscopy. Its anchoring process has been analyzed using scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The growth behavior was directly contrasted to the one of the parent complex fac-Re(bpy)(CO)3Cl (bpy = 2,2′-bipyridine). The sulfurated complex nucleates as single molecule at different surface sites and at molecule clusters. In contrast, for the parent complex nucleation only occurs in clusters of several molecules at specifically oriented surface steps. While this shows that surface immobilization of the sulfurated complex is more efficient as compared to the parent, symmetry analysis of the STM topographic data supported by DFT calculations indicates that more than 90% of the complexes adsorb in a geometric configuration very similar to the one of the parent complex. Thiolate groups are promising anchors to immobilize catalysts, particularly on coinage metal surfaces, but the anchor group's impact on the local adsorption configuration of the catalyst is often overlooked. Here, the authors study a sulfurated derivative of the prominent Re(bpy)(CO)3Cl carbon dioxide reduction catalysts on a Ag(001) surface at room temperature. [ABSTRACT FROM AUTHOR]

The synthesis of the new bulky vinyllithium reagent (MeIPr=CH)Li, (MeIPr=[(MeCNDipp)2C]; Dipp=2,6‐iPr2C6H3) is reported. This vinyllithium precursor was found to act as a general source of the anionic 2σ, 2π‐electron donor ligand [MeIPr=CH]−. Furthermore, a high‐yielding route to the degradation‐resistant SiII precursor MeIPr⋅SiBr2 is presented. The efficacy of (MeIPr=CH)Li in synthesis was demonstrated by the generation of a complete inorganic divinyltetrelene series (MeIPrCH)2E: (E=Si to Pb). (MeIPrCH)2Si: represents the first two‐coordinate acyclic silylene not bound by heteroatom donors, with dual electrophilic and nucleophilic character at the SiII center noted. Cyclic voltammetry shows this electron‐rich silylene to be a potent reducing agent, rivalling the reducing power of the 19‐electron complex cobaltocene (Cp2Co). [ABSTRACT FROM AUTHOR]