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Protonated and methylated bis-acridinium tweezers built around a 2,6-diphenylpyridyl and an electron enriched 2,6-di(p-anisyl)pyridyl spacer have been synthesized. These tweezers can self-assemble in their corresponding homodimers and the associated thermodynamic parameters have been probed in organic solvents. The switching properties of the tweezers have been exploited in biphasic transfer experiments showing the shift of the equilibria towards the homodimers. Moreover, the thermodynamic parameters of the formation of the reduced methylated homodimers investigated by electrochemical experiments revealed the dissociation of the dimers. Thus, in addition to solvent and temperature, the pH and redox responsiveness of the acridinium units of the tweezers make it possible to modulate to a larger extent the monomer-dimer equilibria., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The ability of triaryltelluronium salts to interact with N-halosuccinimides (NXS) through chalcogen bonding (ChB) in the solid state and in solution is demonstrated herein. Cocrystals of the triaryltelluronium bearing two CF 3 electron-withdrawing groups per aryl ring with N-chloro-, N-bromo- and N-iodosuccinimide (respectively NCS, NBS and NIS) were analyzed by X-ray diffraction, evidencing a ChB between tellurium and the carbonyl group of NXS. This ChB was confirmed in solution by NMR spectroscopy, especially by 125 Te NMR titration experiment, which allowed the determination of the association constant (K a ) between the telluronium and NBS. The so-obtained K a value of 17.3±0.6 M -1 indicated a moderate interaction in solution because of the competitive role of the solvent. The strength of the Te⋅⋅⋅O ChB was however sufficient enough to promote the catalytic halofunctionalization of aromatics and of alkenes such as the intra- and intermolecular haloalkoxylation and haloesterification of alkenes., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

A diradical with engineered g-asymmetry was synthesized by grafting a nitroxide radical onto the [Y(Pc) 2 ]⋅ radical platform. Various spectroscopic techniques and computational studies revealed that the electronic structures of the two spin systems remained minimally affected within the diradical system. Fluid-solution Electron Paramagnetic Resonance (EPR) experiments revealed a weak exchange coupling with |J| ~ 0.014 cm -1 , subsequently rationalized by CAS-SCF calculations. Frozen solution continuous-wave (CW) EPR experiments showed a complicated and power-dependent spectrum that eluded analysis using the point-dipole model. Pulse EPR manipulations with varying microwave powers, or under varying magnetic fields, demonstrated that different resonances could be selectively enhanced or suppressed, based on their different tipping angles. In particular, Field-Swept Echo-Detected (FSED) spectra revealed absorptions of MW power-dependent intensities, while Field-Swept Spin Nutation (FSSN) experiments revealed two distinct Rabi frequencies. This study introduces a methodology to synthesize and characterize g-asymmetric two-spin systems, of interest in the implementation of spin-based CNOT gates., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

A [2+3] chiral covalent organic cage is produced through a dynamic covalent chemistry approach by mixing two readily available building units, viz. an enantiopure 3,3'-diformyl 2,2'-BINOL compound (A) with a triamino spacer (B). The two enantiomeric (R,R,R) and (S,S,S) forms of the cage C are formed nearly quantitatively thanks to the reversibility of the imine linkage. The X-ray diffraction analysis of cage (S,S,S)-C highlights that the six OH functions of the BINOL fragments are positioned inside the cage cavity. Upon reduction of the imine bonds of cage C, the amine cage D is obtained. The ability of the cage D to host the 1-phenylethylammonium cation (EH + ) as a guest is evaluated through UV, CD and DOSY NMR studies. A higher binding constant for (R)-EH + cation (Ka=1.7 10 6 ±10 % M -1 ) related to (S)-EH + (Ka=0.9 10 6 ±10 % M -1 ) is determined in the presence of the (R,R,R)-D cage. This enantiopreference is in close agreement with molecular dynamics simulation., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The aromatic Cope rearrangement is an elusive transformation that has been the subject of a limited number of investigations compared to those seemingly close analogues, namely the Cope and aromatic Claisen rearrangement. Herein we report our investigations inspired by moderate success observed in the course of pioneering works. By careful experimental and theoretical investigations, we demonstrate that key substitutions on 1,5-hexadiene scaffold allow fruitful transformations. Especially, efficient functionalisation of the heteroaromatic rings results from the aromatic Cope rearrangement, while highly stereoselective interrupted aromatic Cope rearrangements highlight the formation of chiral compounds through a dearomative process., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Cu-thiosemicarbazones have been intensively investigated for their application in cancer therapy or as antimicrobials. Copper(II)-di-2-pyridylketone-4,4-dimethyl-thiosemicarbazone (Cu II -Dp44mT) showed anticancer activity in the submicromolar concentration range in cell culture. The interaction of Cu II -Dp44mT with thiols leading to their depletion or inhibition was proposed to be involved in this activity. Indeed, Cu II -Dp44mT can catalyze the oxidation of thiols although with slow kinetics. The present work aims to obtain insights into the catalytic activity and selectivity of Cu II -Dp44mT toward the oxidation of different biologically relevant thiols. Reduced glutathione (GSH), L-cysteine (Cys), N-acetylcysteine (NAC), D-penicillamine (D-Pen), and the two model proteins glutaredoxin (Grx) and thioredoxin (Trx) were investigated. Cu II -Dp44mT catalyzed the oxidation of these thiols with different kinetics, with rates in the following order D-Pen>Cys≫NAC>GSH and Trx>Grx. Cu II -Dp44mT was more efficient than Cu II chloride for the oxidation of NAC and GSH, but not D-Pen and Cys. In mixtures of biologically relevant concentrations of GSH and either Cys, Trx, or Grx, the oxidation kinetics and spectral properties were similar to that of GSH alone, indicating that the interaction of these thiols with Cu II -Dp44mT is dominated by GSH. Hence GSH could protect other thiols against potential deleterious oxidation by Cu II -Dp44mT., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Slightly different reaction conditions afforded two distinct cavity-shaped cis-chelating diphosphanes from the same starting materials, namely diphenyl(2-phosphanylphenyl)phosphane and an α-cyclodextrin-derived dimesylate. Thanks to their metal-confining properties, the two diphosphanes form only mononuclear [CuX(PP)] complexes (X=Cl, Br, or I) with the tricoordinated metal ion located just above the center of the cavity. The two series of Cu I complexes display markedly different luminescence properties that are both influenced by the electronic properties of the ligand and the unique steric environment provided by the cyclodextrin (CD) cavity. The excited state lifetimes of all complexes are significantly longer than those of the cavity-free analogues suggesting peculiar electronic effects that affect radiative deactivation constants. The overall picture stemming from absorption and emission data suggests close-lying charge-transfer (MLCT, XLCT) and triplet ligand-centered (LC) excited states., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Telluronium salts [Ar 2 MeTe]X were synthesized, and their Lewis acidic properties towards a number of Lewis bases were addressed in solution by physical and theoretical means. Structural X-ray diffraction analysis of 21 different salts revealed the electrophilicity of the Te centers in their interactions with anions. Telluroniums' propensity to form Lewis pairs was investigated with OPPh 3 . Diffusion-ordered NMR spectroscopy suggested that telluroniums can bind up to three OPPh 3 molecules. Isotherm titration calorimetry showed that the related heats of association in 1,2-dichloroethane depend on the electronic properties of the substituents of the aryl moiety and on the nature of the counterion. The enthalpies of first association of OPPh 3 span -0.5 to -5 kcal mol -1 . Study of the affinity of telluroniums for OPPh 3 by state-of-the-art DFT and ab-initio methods revealed the dominant Coulombic and dispersion interactions as well as an entropic effect favoring association in solution. Intermolecular orbital interactions between [Ar 2 MeTe] + cations and OPPh 3 are deemed insufficient on their own to ensure the cohesion of [Ar 2 MeTe ⋅ B n ] + complexes in solution (B=Lewis base). Comparison of Grimme's and Tkatchenko's DFT-D4/MBD-vdW thermodynamics of formation of higher [Ar 2 MeTe ⋅ B n ] + complexes revealed significant molecular size-dependent divergence of the two methodologies, with MBD yielding better agreement with experiment., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Chalcogen bonding (ChB) is the non-covalent interaction occurring between chalcogen atoms as Lewis acid sites and atoms or groups of atoms able to behave as Lewis bases through their lone pair or π electrons. Analogously to its sister halogen bonding, the high directionality of this interaction was implemented for precise structural organizations in the solid state and in solution. Regarding catalysis, ChB is now accepted as a new mode of activation as demonstrated by the increased number of examples in the last five years. In the family of ChB catalysts, those based on tellurium rapidly appeared to overcome their lighter sulfur and selenium counterparts. In this review, we highlight the Lewis acid properties of tellurium-based derivatives in solution and summarize the start-of-the-art of their applications in catalysis., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Chiroptical materials are gaining increasing interest due to their innovative character and their applications in optoelectronics and data encryption technologies. Fully harnessing the potential of building blocks from the "chiral pool", such as native cyclodextrins (CDs), as they often lack chromophores suitable for the construction of materials with significant chiroptical properties. Here, we present the synthesis and characterization of a two-level molecular stack consisting of a point-chiral element (CD) and an axially chiral element (biphenyl), capable of effectively translating the overall stereochemical information contained in CDs into stimuli-responsive chiroptical properties. α- and β-permethylated CDs were efficiently capped with two different 2,2'-difunctionalized 1,1'-biphenyl units. In CD derivatives containing the rigid 2,2'-dihydroxy-1,1'-biphenyl cap, two intramolecular hydrogen bonds act synergistically as stereoselective actuators, enabling effective communication between the two levels and the transfer of nonchromophoric stereochemical information from the cyclic-oligosaccharide to the atropoisomeric cap. The chiroptical properties can be finely tuned by external stimuli such as temperature and solvent. The way chirality is transferred from the CD platform to the biphenyl cap was revealed thanks to crystallographic and computational analyses, together with electronic circular dichroism (ECD) studies., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The performance of six newly synthesized benzo[h]quinoline-derived acetonitrilo pentamethylcyclopentadienyl iridium(III) tetrakis(3,5-bis-trifluoromethylphenyl)borate salts bearing different substituents -X (-OMe, -H, -Cl, -Br, -NO 2 and -(NO 2 ) 2 ) on the heterochelating ligand were evaluated in the dehydro-O-silylation of benzyl alcohol and the monohydrosilylation of 4-methoxybenzonitrile by Et 3 SiH, two reactions involving the electrophilic activation of the Si-H bond. The benchmark shows a direct dependence of the catalytic efficiency with the electronic effect of -X, which is confirmed by theoretical assessment of the intrinsic silylicities Π of hydridoiridium(III)-silylium adducts and by the theoretical evaluation of the propensity of hydridospecies to transfer the hydrido ligand to the activated substrate. The revisited analysis of the Ir-Si-H interactions shows that the most cohesive bond in hydridoiridium(III)-silylium adducts is the Ir-H one, while the Ir-Si is a weak donor-acceptor dative bond. The Si…H interaction in all the cases is noncovalent in nature and dominated by electrostatics confirming the heterolytic cleavage of the hydrosilane's Si-H bond in this key catalytically relevant species., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Carbonylmetallates [m] - , such as [MoCp(CO) 3 ] - , [Mn(CO) 5 ] - , [Co(CO) 4 ] - , have long been successfully used in the preparation of hundreds of metal-metal bonded carbonyl complexes and clusters, in particular of the heterometallic type. We focus here on situations where [m] - can be viewed as a terminal, doubly or even triply bridging metalloligand, developing metal-metal interactions with one, two or three metal centers M, respectively. With metals M from the Groups 10-12, it is not straightforward or even impossible to rationalize the structure of the resulting clusters by applying the well-known Wade-Mingos rules. A very simple but global approach is presented to rationalize structures not obeying usual electron-counting rules by considering the anionic building blocks [m] - as metalloligands behaving formally as potential 2-, 4- or 6-electron donors, similarly to what is typically encountered with for example halido ligands. Qualitative and theoretical arguments by using DFT calculations highlight similarities between seemingly unrelated metal complexes and clusters and also entail a predicting power with high synthetic potential., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

In the chalcogen series, tellurium species exhibit the strongest chalcogen bonding (ChB) interaction with electron-rich atom. This property explains the renewed interested toward tellurium-based derivatives and their use in different applications, such as organocatalysis. In this context, the catalytic activity of telluronium salts in the Povarov reaction is presented herein. Different dienophiles, as well as imines of variable electronic nature, efficiently react in the presence of catalytic amount of either diarylmethyltelluronium or triaryltelluronium salts. Both catalysts could also readily perform the three-component Povarov reaction starting from aldehyde, aniline and dihydrofuran. The reactivity of telluroniums towards imines and aldehydes was confirmed in the solid state by the ability of Te atom to interact through ChB with the oxygen carbonyl of acetone, and in solution with significant shift variations of the imine proton and of the tellurium atom in 1 H and 125 Te NMR spectroscopy. For the most active telluronium catalysts bearing CF 3 groups, association constants (K) with N-phenyl phenylmethanimine in the range 22-38 M -1 were measured in dichloromethane., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Photoreduction of perylenediimide (PDI) derivatives has been widely studied for use in photocatalysis, hydrogen evolution, photo-responsive gels, and organic semiconductors. Upon light irradiation, the radical anion (PDI⋅ - ) can readily be obtained, whereas further reduction to the dianion (PDI 2- ) is rare. Here we show that full 2-electron photoreduction can be achieved using UVC light: 1) in anaerobic conditions by 'direct photoreduction' of PDI aggregates, or 2) by 'indirect photoreduction' in aerobic conditions due to acetone ketyl radicals. The latter strategy is also efficient for other dyes, such as naphthalenediimide (NDI) and methylviologen (MV 2+ ). Efficient photoreduction on the minute time-scale using simple LED light in aerobic conditions is attractive for use in dissipative light-driven systems and materials., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

A [2]rotaxane built around a multi-responsive bis-acridinium macrocycle has been synthesized. Structural investigation has confirmed the interlocked nature of the molecule, and MD simulations illuminated its conformational dynamics with atomic resolution. Both halochromic and redox-switching properties were explored to shed light on the mechanical response and electronic changes that occur in the bis-acridinium [2]rotaxane. The topology of the rotaxane led to different mechanical behaviors upon addition of hydroxide ions or reduction that were easily detected by UV/Vis spectroscopy and electrochemistry., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The neutral complex dichloro-{diethyl[(5-phenyl-1,3,4-oxadiazol-2-ylamino)-(4-trifluoro-methylphenyl)methyl]phosphonate} (p-cymene)-ruthenium(II) was encapsulated inside a self-assembled hexameric host obtained upon reaction of 2,8,14,20-tetra-undecyl-resorcin[4]arene and water. The formation of an inclusion complex was inferred from a combination of spectral measurements (MS, UV/Vis spectroscopy, 1 H and DOSY NMR). The 31 P and 19 F NMR spectra are consistent with motions of the ruthenium complex inside the self-assembled capsule. Molecular dynamics simulations carried out on the inclusion complex confirmed these intra-cavity movements and highlighted possible supramolecular interactions between the ruthenium first coordination sphere ligands and the inner part (aromatic rings) of the capsule. The embedded ruthenium complex was assessed in the catalytic oxidation (using NaIO 4 as oxidant) of mixtures of three arylmethyl alcohols into the corresponding aldehydes. The reaction kinetics were shown to vary as a function of the substrates' size, with the oxidation rate varying in the order benzylalcohol >4-phenyl-benzylalcohol >9-anthracenemethanol. Control experiments realized in the absence of hexameric capsule did not allow any discrimination between the substrates., (© 2022 Wiley-VCH GmbH.)

We report the first examples of metal-promoted double geminal activation of C(sp 3 )-H bonds of the N-CH 2 -N moiety in an imidazole-type heterocycle, leading to nickel and palladium N-heterocyclic carbene complexes under mild conditions. Reaction of the new electron-rich diphosphine 1,3-bis((di-tert-butylphosphaneyl)methyl)-2,3-dihydro-1H-benzo[d]imidazole (1) with [PdCl 2 (cod)] occurred in a stepwise fashion, first by single C-H bond activation yielding the alkyl pincer complex [PdCl(PC sp 3 H P)] (3) with two trans phosphane donors and a covalent Pd-C sp 3 bond. Activation of the C-H bond of the resulting α-methine C sp 3 H-M group occurred subsequently when 3 was treated with HCl to yield the NHC pincer complex [PdCl(PC NHC P)]Cl (2). Treatment of 1 with [NiBr 2 (dme)] also afforded a NHC pincer complex, [NiBr(PC NHC P)]Br (6), but the reactions leading to the double geminal C-H bond activation of the N-CH 2 -N group were too fast to allow identification or isolation of an intermediate analogous to 3. The determination of six crystal structures, the isolation of reaction intermediates and DFT calculations provided the basis for suggesting the mechanism of the stepwise transformation of a N-CH 2 -N moiety in the N-C NHC -N unit of NHC pincer complexes and explain the key differences observed between the Pd and Ni chemistries., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

IspG (also called GcpE) is an oxygen-sensitive [4Fe-4S] enzyme catalyzing the penultimate step of the methylerythritol phosphate (MEP) pathway, a validated target for drug development. It converts 2-C-methyl-d-erythritol-2,4-cyclo-diphosphate (MEcPP) into (E)-4-hydroxy-3-methyl-but-2-enyl-1-diphosphate (HMBPP). The reaction, assimilated to a reductive dehydration, involves redox partners responsible for the formal transfer of two electrons to substrate MEcPP. The 2-vinyl analogue of MEcPP was designed to generate conjugated species during enzyme catalysis, with the aim of providing new reactive centers to be covalently trapped by neighboring amino acid residues. The synthesized substrate analogue displayed irreversible inhibition towards IspG. Furthermore, we have shown that electron transfer occurs prior to inhibition; this might designate conjugated intermediates as probable affinity tags through covalent interaction at the catalytic site. This is the first report of an irreversible inhibitor of the IspG metalloenzyme., (© 2022 Wiley-VCH GmbH.)

The chalcogen bonding (ChB) ability of Te is studied in symmetrical diaryl ditellurides ArTeTeAr. Among the two Te σ-holes, the one along the less polarized Te-Te bond was calculated as the more electropositive. This counter-intuitive situation is due to the hyperconjugation contribution from Te lone pair to the σ* of the adjacent Te which coincides with σ-hole along the more polarized Te-Ar bond. ArTeTeAr showed notable structural features in the solid state as a result of intermolecular Te⋅⋅⋅Te ChB, such as a Te 4 rectangle through dimer aggregation or a triangular Te 3 motif, where one Te interacts with both Te atoms of a neighboring molecule through both its σ-hole and lone pair, in a slightly frustrated geometry. Lewis acidity of ArTeTeAr was also evaluated by NMR with R 3 PO as σ-hole acceptors in different solvents. Thus, 125 Te NMR allowed monitoring Te⋅⋅⋅O interaction and delivering association constants (K a ) for 1 : 1 adducts. The highest value of K a =90 M -1 was measured for the adduct between ArTeTeAr bearing CF 3 groups and Et 3 PO in cyclohexane. Notably, by using nBu 3 PO, Te⋅⋅⋅O interaction was revealed by 19 F- 1 H HOESY showing spatial proximity between CF 3 and CH 3 of nBu 3 PO., (© 2022 Wiley-VCH GmbH.)

The syntheses and properties of expanded 4-tert-butyl-mercaptocalix[4]arenes, in which the methylene linkers are replaced by -CH 2 NRCH 2 - or -CH 2 NRCH 2 - and -CH 2 NRCH 2 CH 2 CH 2 NRCH 2 - units, are described. The new macrocycles were obtained in a step-wise manner, utilizing fully protected, i. e. S-alkylated, derivatives of the oxidation-sensitive thiophenols in the cyclisation steps. Reductive cleavage of the macrobicyclic or macrotricyclic intermediates (6, 7, 11) afforded the free thiophenols (H 4 8, H 4 9, and H 4 12) in preparative yields as their hydrochloride salts. The protected proligands can exist in two conformations, resembling the "cone" and "1,3-alternate" conformations found for the parent calix[4]arenes. The free macrocycles do not show conformational isomerism, but are readily oxidized forming intramolecular disulfide linkages. Preliminary complexation experiments show that these expanded mercaptocalixarenes can serve as supporting ligands for tetranuclear thiolato clusters., (© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The formation of a tetranuclear self-assembled species constructed around a TiO 4 N 2 motif is reported. This aggregate is generated from Ti(O i Pr) 4 , 2,2'-bipyrimidine (bpym) and a bis-biphenol strand (L 2 H 4 ) where two 2,2'-biphenol units are connected with a biphenyl spacer. The solid-state structure of the [Ti 4 (L 2 ) 4 (bpym) 4 ] architecture reveals the formation of an unprecedented chiral alternate [2×2] grid. In addition to the structural characterization of the [Ti 4 (L 2 ) 4 (bpym) 4 ] architecture, geometry optimisation on various possible isomeric tetrameric assemblies ([2×2] grid, alternate [2×2] grid, circular helicate or cyclic hemihelicate) is performed using DFT calculations. These results confirm the higher stability of the alternate [2×2] grid over the other possible tetranuclear isomers and allow examining the replacement of the bpym ligands by two novel diimine chelates within the tetranuclear assembly (2,2'-bipyridine=bipy and 2,2'-bipyrazine=bipyraz). From this initial theoretical investigation, the competition between these three nitrogen ligands in the course of the self-assembly process is next evaluated. Overall, this investigation shows that the exclusive formation of the alternate [2×2] grid is driven by CH⋅⋅⋅N interactions., (© 2022 Wiley-VCH GmbH.)

Using a pincer platform based on a bridgehead NHC donor with functional side arms, the combined effect of increased flexibility in six-membered pyrimidine-type heterocycles compared to the more often studied five-membered imidazole, and rigidity of phosphane side arms was examined. The unique features observed include: 1) the reaction of the azolium C sp2 -H bond with [Ni(cod) 2 ] affording a carbanionic ligand in [NiCl(PC sp3 H P)] (8) rather than a carbene; 2) its transformation into the NHC, hydrido complex [NiH(PC NHC P)]PF 6 (9) upon halide abstraction; 3) ethylene insertion into the Ni-H bond of the latter and ethyl migration to the N-C-N carbon atom of the heterocycle in [Ni(PC Et P)]PF 6 (10); and 4) an unprecedented C-P bond activation transforming the P-C NHC -P pincer ligand of 8 in a C-C NHC -P pincer and a terminal phosphanido ligand in [Ni(PPh 2 )(CC NHC P)] (15). The data are supported by nine crystal structure determinations and theoretical calculations provided insights into the mechanisms of these transformations, which are relevant to stoichiometric and catalytic steps of general interest., (© 2022 Wiley-VCH GmbH.)

Chiral gold(I) acetylide trinuclear complexes 1-3 based on the cyclotribenzylene platform and terminal PR 3 ligands (R=Ph, Et, and Cy, respectively), were characterized and their light emission studied. They exhibited long-lived blue phosphorescence in CHCl 3 and a weak fluorescence in the UV. In MeOH/CHCl 3 mixtures of >1:1 volume ratio, 1 and 2 exhibited a new emission band at ca. 540 nm that developed at the expense of the UV emission. DLS studies demonstrated the presence of molecular aggregates of Ø 30-80 nm. The green emission observed in MeOH-rich solvent mixtures was therefore induced by aggregation, and could originate from Au⋅⋅⋅Au interactions. The AIE spectrum of 3 was observed only in solutions containing 99 % of MeOH, and correlated with its solid state emission. The AIE profiles of the enantiomers of 1 differed from that of rac-1, suggesting that the latter is a true racemate., (© 2021 Wiley-VCH GmbH.)

A copper-mediated coupling reaction between ynamides and diazo-compounds to produce N-allenamides is reported for the first time. This method enables facile and rapid access to terminal N-allenamides by using commercially available TMS-diazomethane with wide functional group compatibility on the nitrogen. Furthermore, the ubiquity of molecules containing a fluorine moiety in medicine, in agricultural, and material science requires the continuous search of new building blocks, including this unique surrogate. The CuI/diazo protocol was successfully applied to the synthesis of fluorine-substituted N-allenamides. DFT calculations provided insights in the mechanism involved., (© 2021 Wiley-VCH GmbH.)

The synergistic functioning of redox-active components that emerges from prototypical 2,2'-di(N-methylpyrid-4-ylium)-1,1'-biphenyl is described. Interestingly, even if a trans conformation of the native assembly is expected, due to electrostatic repulsion between cationic pyridinium units, we demonstrate that cis conformation is equally energy-stabilized on account of a peculiar LUMO (SupLUMO) that develops through space, encompassing the two pyridiniums in a single, made-in-one-piece, electronic entity (superelectrophoric behavior). This SupLUMO emergence, with the cis species as superelectrophore embodiment, originates in a sudden change of electronic structure. This finding is substantiated by insights from solid state (single-crystal X-ray diffraction) and solution (NOE NMR and UV-vis-NIR spectroelectrochemistry) studies, combined with electronic structure computations. Electrochemistry shows that electron transfers are so strongly correlated that two-electron reduction manifests itself as a single-step process with a large potential inversion consistent with inner creation of a carbon-carbon bond (digital simulation). Besides, absence of reductive formation of dimers is a further indication of a preferential intramolecular reactivity determined by the SupLUMO interaction (cis isomer pre-organization). The redox-gated covalent bond, serving as electron reservoir, was studied via atropisomerism of the reduction product (VT NMR study). The overall picture derived from this in-depth study of 2,2'-di(N-methylpyrid-4-ylium)-1,1'-biphenyl proves that trans and cis species are worth considered as intrinsically sharply different, that is, as doubly-electrophoric and singly-superelectrophoric switchable assemblies, beyond conformational isomerism. Most importantly, the through-space-mediated SupLUMO may come in complement of other weak interactions encountered in Supramolecular Chemistry as a tool for the design of electroactive architectures., (© 2021 Wiley-VCH GmbH.)

Polyoxometalates (POMs) can act as unique reservoirs for multiple electron transfers. As POMs display only weak absorption in the visible spectrum, they can be associated with chromophores such as porphyrins and porphyrin antennae. In this Minireview, the research dedicated to the combination of porphyrins and polyoxometalates is put in context and the state of the art identifying the challenges addressed in the optimization of hybrid materials for applications is detailed., (© 2021 Wiley-VCH GmbH.)

The 36-Ni II -containing 54-tungsto-6-silicate, [Ni 36 (OH) 18 (H 2 O) 36 (SiW 9 O 34 ) 6 ] 6- (Ni 36 ) was synthesized by a simple one-pot reaction of the Ni 2 -pivalate complex [Ni 2 (μ-OH 2 )(O 2 CCMe 3 ) 4 (HO 2 CCMe 3 ) 4 ] with the trilacunary [SiW 9 O 34 ] 10- polyanion precursor in water and structurally characterized by a multitude of physicochemical techniques including single-crystal XRD, FTIR, TGA, elemental analysis, magnetic and electrochemical studies. Polyanion Ni 36 comprises six equivalent {Ni II 6 SiW 9 } units which are linked by Ni-O-W bridges forming a macrocyclic assembly. Magnetic studies demonstrate that the {Ni 6 } building blocks in Ni 36 remain magnetically intact while forming a hexagonal ring with antiferromagnetic exchange interactions between adjacent {Ni 6 } units. Electrochemical studies indicate that the first reduction is reversible and associated with the W VI/V couple, whereas the second reduction is irreversible attributed to the Ni II/0 couple., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Since the beginning of the 2000's, homogeneous gold catalysis has emerged as a powerful tool to promote the cyclization of unsaturated substrates with excellent regioselectivity allowing the synthesis of elaborated organic scaffolds. An important goal to achieve in gold catalysis is the possibility to induce enantioselective transformations by the assistance of chiral complexes. Unfortunately, the linear geometry of coordination for gold usually encountered in complexes at the +1 oxidation states renders this goal very challenging. In consequence, the interest toward the synthesis of chiral gold(III) complexes is steadily growing. Indeed, the square planar geometry of the gold(III) cation appears more suitable to promote chiral induction. Beside catalysis, gold(III) complexes have also shown promising potential in the field of pharmacology. Herein, syntheses and applications of well-defined gold(III) complexes reported over the last fifteen years are summarized., (© 2021 Wiley-VCH GmbH.)

Spin triangles, that is, triangular complexes of half-integer spins, are the oldest molecular nanomagnets (MNMs). Their magnetic properties have been studied long before molecular magnetism was delineated as a research field. This Review presents the history of their study, with references to the parallel development of new experimental investigations and new theoretical ideas used for their interpretation. It then presents an indicative list of spin-triangle families to illustrate their chemical diversity. Finally, it makes reference to recent developments in terms of theoretical ideas and new phenomena, as well as to the relevance of spin triangles to spintronic devices and new physics., (© 2020 Wiley-VCH GmbH.)

Herein, the reaction of (1-methyl-1 H-benzo[d]imidazol-2-yl)methanamine (L1) with Co(H 2 O) 6 Cl 2 , in CH 3 CN at 120 °C, leading to the 2,3,5,6-tetrakis(1-methyl-1 H-benzo[d]imidazol-2-yl)pyrazine (3), isolated as a dimeric cluster {[Co II 2 (3)Cl 4 ]⋅2 CH 3 CN} (2), is reported. When O 2 and H 2 O are present, (1-methyl-1 H-benzo[d]imidazole-2-carbonyl)amide (HL1') is first formed and crystallized as [Co III (L1) 2 (L1')]Cl 2 ⋅2 H 2 O (4) before fusion of HL1' with L1, giving 1-methyl-N-(1-methyl-1 H-benzo[d]imidazol-2-carbonyl)-1 H-benzo[d]imidazol-2-carboxamide (HL2'') forming a one-dimensional (1D) chain of [Co II 3 (L2'') 2 Cl 4 ] n (5). The combination of crystallography and mass spectrometry (ESI-MS) of isolated crystals and the solutions taken from the reaction as a function time reveal seven intermediate steps leading to 2, but six steps for 5, for which a different sequence takes place. Control and isotope labeling experiments confirm the two carbonyl oxygen atoms in 5 originate from both air and water. The dependence on the metals, compared with FeCl 3 ⋅6 H 2 O leading to a stable triheteroarylmethyl radical, is quite astounding, which could be attributed to the different oxidation states of the metals and coordination modes confirmed by DFT calculations. This metal and valence dependent process is a very useful way for selectively obtaining these large molecules, which are unachievable by common organic synthesis., (© 2020 Wiley-VCH GmbH.)

Using the redox-active tetrathiafulvalene tetrabenzoate (TTFTB 4- ) as the linker, a series of stable and porous rare-earth metal-organic frameworks (RE-MOFs), [RE 9 (μ 3 -OH) 13 (μ 3 -O)(H 2 O) 9 (TTFTB) 3 ] (1-RE, where RE=Y, Sm, Gd, Tb, Dy, Ho, and Er) were constructed. The RE 9 (μ 3 -OH) 13 (μ 3 -O) (H 2 O) 9 ](CO 2 ) 12 clusters within 1-RE act as segregated single-molecule magnets (SMMs) displaying slow relaxation. Interestingly, upon oxidation by I 2 , the S=0 TTFTB 4- linkers of 1-RE were converted into S= 1 / 2 TTFTB .3- radical linkers which introduced exchange-coupling between SMMs and modulated the relaxation. Furthermore, the SMM property can be restored by reduction in N,N-dimethylformamide. These results highlight the advantage of MOFs in the construction of redox-switchable SMMs., (© 2020 Wiley-VCH GmbH.)

The complexation processes of N,N'-dibutyl-1,4,5,8-naphthalene diimide (NDI) into two types of π-electron-rich molecular containers consisting of two Zn(II)-porphyrins connected by four flexible linkers of two different lengths, were characterized by means of absorption and emission spectroscopies and molecular dynamics simulation. Notably, the addition of NDI leads to a strong quenching of the fluorescence of both cages only when they are in an open conformation suitable for guest encapsulation, a situation triggered by silver(I) ions binding to the lateral triazoles. Molecular dynamics simulations confirm the fast binding of NDI, likely assisted by NDI-silver(I) interactions. Upon NDI complexation, the two porphyrin macrocycles get closer, with an optimized face to face orientation, suggesting an induced-fit mechanism through π-π interactions with the NDI aromatic cycle. Ultrafast transient absorption experiments allowed to identify the process of quenching of the Zn-porphyrin fluorescence as an efficient photoinduced electron transfer reaction between the cage porphyrin and the included NDI guest. The process occurs on fast and ultrafast time scales in the two complexes (1.5 ps and ≤300 fs) leading to a short-lived charge separated state (charge recombination lifetimes in the order of 30-40 ps). The combined computational and experimental approach used here is able to furnish a reliable model of the NDI-cage complexation mechanism and of the corresponding electron transfer reaction, attesting the allosteric control of both processes by the silver(I) ions., (© 2020 Wiley-VCH GmbH.)

Previously reported ferromagnetic triangles (NnBu 4 ) 2 [Cu 3 (μ 3 -Cl) 2 (μ-4-NO 2 -pz) 3 Cl 3 ] (1), (PPN) 2 [Cu 3 (μ 3 -Cl) 2 (μ-pz) 3 Cl 3 ] (2), (bmim) 2 [Cu 3 (μ 3 -Cl) 2 (μ-pz) 3 Cl 3 ] (3) and newly reported (PPh 4 ) 2 [Cu 3 (μ 3 -Cl) 2 (μ-4-Ph-pz) 3 Cl 3 ] (4) were studied by magnetic susceptometry, electron paramagnetic resonance (EPR) spectroscopy and ab initio calculations to assess the origins of their ferromagnetism and of the magnetic anisotropy of their ground S=3/2 state (PPN + =bis(triphenylphosphine)iminium, bmim + =1-butyl-3-methylbenzimidazolium, pz - =pyrazolate). Ab initio studies revealed the d z 2 character of the magnetic orbitals of the compressed trigonal bipyramidal copper(II) ions. Ferromagnetic interactions were attributed to weak orbital overlap via the pyrazolate bridges. From the wavefunctions expansions, the ratios of the magnetic couplings were determined, which were indeterminate by magnetic susceptometry. Single-crystal EPR studies of 1 were carried out to extend the spin Hamiltonian with terms which induce zero-field splitting (zfs), namely dipolar interactions, anisotropic exchange and Dzyaloshinskii-Moriya interactions (DMI). The data were treated through both a giant-spin model and through a multispin exchange-coupled model. The latter indicated that ≈62 % of the zfs is due to anisotropic and ≈38 % due to dipolar interactions. The powder EPR data of all complexes were fitted to a simplified form of the multispin model and the anisotropic and dipolar contributions to the ground state zfs were estimated., (© 2020 Wiley-VCH GmbH.)

The catalytic activity of cationic NHC-Zn II and NHC-Al III (NHC=N-heterocyclic carbene) complexes in reactions that require the electrophilic activation of soft C-C π bonds has been studied. The former proved able to act as a soft π-Lewis acid in a variety of transformations. The benefit of the bulky IPr NHC ligand was demonstrated by comparison with simple ZnX 2 salts. The tested NHC-Al III catalyst is not able to activate C-C π bonds but simple AlX 2 + ions were found potent in some cases., (© 2020 Wiley-VCH GmbH.)

A strategy is presented to improve the excited state reactivity of homoleptic copper-bis(diimine) complexes CuL 2 + by increasing the steric bulk around Cu I whereas preserving their stability. Substituting the phenanthroline at the 2-position by a phenyl group allows the implementation of stabilizing intramolecular π stacking within the copper complex, whereas tethering a branched alkyl chain at the 9-position provides enough steric bulk to rise the excited state energy E 00 . Two novel complexes are studied and compared to symmetrical models. The impact of breaking the symmetry of phenanthroline ligands on the photophysical properties of the complexes is analyzed and rationalized thanks to a combined theoretical and experimental study. The importance of fine-tuning the steric bulk of the N-N chelate in order to stabilize the coordination sphere is demonstrated. Importantly, the excited state reactivity of the newly developed complexes is improved as demonstrated in the frame of a reductive quenching step, evidencing the relevance of our strategy., (© 2020 Wiley-VCH GmbH.)

A novel class of phosphorescent cationic heterobimetallic Ir III /M I complexes, where M I =Cu I (4) and Au I (5), is reported. The two metal centers are connected by the hybrid bridging 1,3-dimesityl-5-acetylimidazol-2-ylidene-4-olate (IMesAcac) ligand that combines both a chelating acetylacetonato-like and a monodentate N-heterocyclic carbene site coordinated onto an Ir III and a M I center, respectively. Complexes 4 and 5 have been prepared straightforwardly by a stepwise site-selective metalation with the zwitterionic [(IPr)M I (IMesAcac)] metalloproligand (IPr=1,3-(2,6-diisopropylphenyl)-2H-imidazol-2-ylidene) and they have been fully characterized by spectroscopic, electrochemical, and computational investigation. Complexes 4 and 5 display intense red emission arising from a low-energy excited state that is located onto the "Ir(C^N)" moiety featuring an admixed triplet ligand-centered/metal-to-ligand charge transfer ( 3 IL/ 1 MLCT) character. Comparison with the benchmark mononuclear complexes reveals negligible electronic coupling between the two distal metal centers at the electronic ground state. The bimetallic systems display enhanced photophysical properties in comparison with the parental congeners. Noteworthy, similar non-radiative rate constants have been determined along with a two-fold increase of radiative rate, yielding brightly red-emitting cyclometalating Ir III complexes. This finding is ascribed to the increased MLCT character of the emitting state in complexes 4 and 5 due to the smaller energy gap between the 3 IL and 1 MLCT manifolds, which mix via spin-orbit coupling., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The nuclear coactivator binding domain (NCBD) of transcriptional co-regulator CREB-binding protein (CBP) is an example of conformationally malleable proteins that can bind to structurally unrelated protein targets and adopt distinct folds in the respective protein complexes. Here, we show that the folding landscape of NCBD contains an alternative pathway that results in protein aggregation and self-assembly into amyloid fibers. The initial steps of such protein misfolding are driven by intermolecular interactions of its N-terminal α-helix bringing multiple NCBD molecules into contact. These oligomers then undergo slow but progressive interconversion into β-sheet-containing aggregates. To reveal the concealed aggregation potential of NCBD we used a chemically synthesized mirror-image d-NCBD form. The addition of d-NCBD promoted self-assembly into amyloid precipitates presumably due to formation of thermodynamically more stable racemic β-sheet structures. The unexpected aggregation of NCBD needs to be taken into consideration given the multitude of protein-protein interactions and resulting biological functions mediated by CBP., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Mounting evidence supports the role of amyloidogenesis, oxidative stress, and metal dyshomeostasis in the development of neurodegenerative disorders. Parkinson's Disease is characterized by α-synuclein (αSyn) accumulation and aggregation in brain regions, also promoted by Cu 2+ . αSyn is modified by reactive carbonyl species, including acrolein (ACR). Notwithstanding these findings, the interplay between ACR, copper, and αSyn has never been investigated. Therefore, we explored more thoroughly the effects of ACR on αSyn using an approach based on LC-MS/MS analysis. We also evaluated the influence of Cu 2+ on the protein carbonylation and how the ACR modification impacts the Cu 2+ binding and the production of Reactive Oxygen Species (ROS). Finally, we investigated the effects of ACR and Cu 2+ ions on the αSyn aggregation by dynamic light scattering and fluorescence assays. Cu 2+ regioselectively inhibits the modification of His50 by ACR, the carbonylation lowers the affinity of His50 for Cu 2+ and ACR inhibits αSyn aggregation both in the presence and in the absence of Cu 2+ ., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

IspH/LytB, an oxygen-sensitive [4Fe-4S] enzyme, catalyzes the last step of the methylerythritol phosphate (MEP) pathway, a target for the development of new antimicrobial agents. This metalloenzyme converts (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMBPP) into the two isoprenoid precursors: isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). Here, the synthesis of (S)-[4- 2 H 1 ]HMBPP and (R)-[4- 2 H 1 ]HMBPP is reported together with a detailed NMR analysis of the products formed after their respective incubation with E. coli IspH/LytB in the presence of the biological reduction system used by E. coli to reduce the [4Fe-4S] center. (S)-[4- 2 H 1 ]HMBPP was converted into [4- 2 H 1 ]DMAPP and (E)-[4- 2 H 1 ]IPP, whereas (R)-[4- 2 H 1 ]HMBPP yielded [4- 2 H 1 ]DMAPP and (Z)-[4- 2 H 1 ]IPP, hence providing the direct enzymatic evidence that the mechanism catalyzed by IspH/LytB involves a rotation of the CH 2 OH group of the substrate to display it away from the [4Fe-4S]., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dehydration of (S,S)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethane-1,2-diol (H 4 L) to (Z)-1,2-bis(1H-benzo[d]imidazol-2-yl)ethenol) (H 3 L') was found to be metal-assisted, occurs under solvothermal conditions (H 2 O/CH 3 OH), and leads to [Mn II 4 (H 3 L) 4 Cl 2 ]Cl 2 ⋅5 H 2 O⋅5 CH 3 OH (Mn 4 L 4 ) and [Mn II 4 (H 2 L') 6 (μ 3 -OH)]Cl⋅4 CH 3 OH⋅H 2 O (Mn 4 L' 6 ), respectively. Their structures were determined by single-crystal XRD. Extensive ESI-MS studies on solutions and solids of the reaction led to the proposal consisting of an initial stepwise assembly of Mn 4 L 4 from the reactants via [MnL] and [Mn 2 L 2 ] below 80 °C, and then disassembly to [MnL] and [MnL 2 ] followed by ligand modification before reassembly to Mn 4 L' 6 via [MnL'], [MnL' 2 ], and [Mn 2 L' 3 ] with increasing solvothermal temperature up to 140 °C. Identification of intermediates [Mn 4 L x L' 6-x ] (x=5, 4, 3, 2, 1) in the process further suggested an assembly/disassembly/in situ reaction/reassembly transformation mechanism. These results not only reveal that multiple phase transformations are possible even though they were not realized in the crystalline state, but also help to better understand the complex transformation process between coordination clusters during "black-box" reactions., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Merging gold(I) cations with polyoxometalate anions results in various interclusters and complexes. Herein, the synthesis of these newly emerging gold(I)/polyoxometalate materials is reviewed. The applications of these promising hybrids in organic catalysis are also summarized and evaluated in terms of the advantages and limitations of the catalysts including efficiency, synergistic effects and recyclability., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reactivity of Zn II dialkyl species ZnMe 2 with a cyclic(alkyl)(amino)carbene, 1-[2,6-bis(1-methylethyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene (CAAC, 1), was studied and extended to the preparation of robust CAAC-supported Zn II Lewis acidic organocations. CAAC adduct of ZnMe 2 (2), formed from a 1:1 mixture of 1 and ZnMe 2 , is unstable at room temperature and readily undergoes a CAAC carbene insertion into the Zn-Me bond to produce the ZnX 2 -type species (CAAC-Me)ZnMe (3), a reactivity further supported by DFT calculations. Despite its limited stability, adduct 2 was cleanly ionized to robust two-coordinate (CAAC)ZnMe + cation (5 + ) and derived into (CAAC)ZnC 6 F 5 + (7 + ), both isolated as B(C 6 F 5 ) 4 - salts, showing the ability of CAAC for the stabilization of reactive [ZnMe] + and [ZnC 6 F 5 ] + moieties. Due to the lability of the CAAC-ZnMe 2 bond, the formation of bis(CAAC) adduct (CAAC) 2 ZnMe + cation (6 + ) was also observed and the corresponding salt [6][B(C 6 F 5 ) 4 ] was structurally characterized. As estimated from experimental and calculations data, cations 5 + and 7 + are highly Lewis acidic species and the stronger Lewis acid 7 + effectively mediates alkene, alkyne and CO 2 hydrosilylation catalysis. All supporting data hints at Lewis acid type activation-functionalization processes. Despite a lower energy LUMO in 5 + and 7 + , their observed reactivity is comparable to those of N-heterocyclic carbene (NHC) analogues, in line with charge-controlled reactions for carbene-stabilized Zn II organocations., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

For ethene derivatives with large groups the cis-isomer is often quite unstable and unavailable. Herein, we report an exception of two stable coordination complexes, (cis-L)ZnCl 2 , starting from trans-1,2-bis(1-R-benzo[d]imidazol-2-yl)ethene (R=H, L1; R=CH 3 , L2) ligands under solvothermal condition (T ≥140 °C). Using the intensity of the absorption and luminescence spectra as probes we proposed its progressive cis-to-trans reversal upon irradiation with UV light, which was confirmed by powder X-ray diffraction (PXRD). Similar results observed in the series of (cis-L2)M II Cl 2 [M=Fe (4), Co (5), Ni (6)] demonstrate the universal strategy. The results of PXRD, NMR spectroscopy, ESI-MS and DFT calculations support the above conclusion. NMR spectroscopy indicates that irradiation of 1 converts an optimized 71 % of the cis-isomer to trans, whereas the free trans-L1 ligand transforms to only 15 % cis-isomer under similar conditions., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of a hemicryptophane cage combining a CTV unit with a C 3 symmetrical moiety bearing three urea functions is reported. This host was found to bind anions with higher binding constants than other previously reported hemicryptophanes. Due to its heteroditopic character this cage proved to be an efficient ion-pair receptor. The best cooperativity effect was observed for the tetramethylammonium bromide (TMABr) salt, which was confirmed and rationalized by DFT calculations., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A computational investigation of the triplet excited states of a rhenium complex electronically coupled with a tryptophan side chain and bound to an azurin protein is presented. In particular, by using high-level molecular modeling, evidence is provided for how the electronic properties of the excited-state manifolds strongly depend on coupling with the environment. Indeed, only upon explicitly taking into account the protein environment can two stable triplet states of metal-to-ligand charge transfer or charge-separated nature be recovered. In addition, it is also demonstrated how the rhenium complex plus tryptophan system in an aqueous environment experiences too much flexibility, which prevents the two chromophores from being electronically coupled. This occurrence disables the formation of a charge-separated state. The successful strategy requires a multiscale approach of combining molecular dynamics and quantum chemistry. In this context, the strategy used to parameterize the force fields for the electronic triplet states of the metal complex is also presented., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The allosteric control of the receptor properties of two flexible covalent cages is reported. These receptors consist of two zinc(II) porphyrins connected by four linkers of two different sizes, each incorporating two 1,2,3-triazolyl ligands. Silver(I) ions act as effectors, responsible for an on/off encapsulation mechanism of neutral guest molecules. Binding silver(I) ions to the triazoles opens the cages and triggers the coordination of pyrazine or the encapsulation of N,N'-dibutyl-1,4,5,8-naphthalene diimide. The X-ray structure of the silver(I)-complexed receptor with short connectors is reported, revealing the hollow structure with a cavity well-defined by two eclipsed porphyrins. Rather unexpectedly, the crystallographic structure of this receptor with pyrazine as a guest molecule showed that the cavity is occupied by two pyrazines, each binding to the zinc(II) porphyrin in a monotopic fashion., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A new way of introducing a N-heterocyclic carbene cap onto cyclodextrins has been devised. The benzimidazolium intermediates were found to behave as receptors towards cavity matching anions. The corresponding C 1 - and C 2 -symmetrical regioisomeric carbene gold(I) complexes have been tested in a benchmark asymmetric cycloisomerization of 1,6-enynes. Up to 50 % ee was achieved for the enantioselective cycloisomerization of N-allyl-4-methyl-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction of H 3 SiR (R=Ph, nBu) with cationic η 5 -C 5 Me 5 - (Cp*) and benzo[h]quinolinyl-based iridacycle [1 b] + gives rise to new [(IrH)→SiRH 2 ] + adducts. In the presence of THF these adducts readily undergo elimination of H 2 gas at subambient temperature to form THF-stabilized metallacyclic Ir III silylene complexes, which were characterized in situ by NMR spectroscopy, trapped in minute amounts by reactive crystallization, and structurally characterized by XRD. Theoretical investigations (static DFT-D reaction-energy profiling, ETS-NOCV) support the promoting role of THF in the H 2 elimination step and the consolidation of the Ir-to-Si interaction in the spontaneous (ΔG<0) formation of Ir silylenes in the presence of THF. Mechanistic insights indicate that the Ir silylene species arising from the [1 b] + /phenylsilane system are relevant catalytic species in the hydrodefluorination of fluoroalkanes., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The condensation of aldehydes and amines in water to give amphiphilic imines can lead to a particular autocatalytic behavior known as autopoiesis, in which the closed micellar structure made by the amphiphile at the mesoscale can accelerate the condensation of its constituents. Herein, through a combination of analytical tools, including diffusion ordered spectroscopy (DOSY) as well as light, neutron, and X-ray scattering techniques, the thermodynamic and kinetic parameters were probed at both the level of dynamic covalent imine bond formation and the level of the resulting micellar self-assemblies. It was found that the autopoietic behavior was the result of a combination of several parameters, including solubilization of hydrophobic building blocks, template effect at the core-shell interface, and growth/division cycles of the micellar objects., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Porphyrins are conjugated, stable chromophores with a central core that binds a variety of metal ions and an easily functionalized peripheral framework. By combining the catalytic, electronic or cytotoxic properties of selected transition metal complexes with the binding and electronic properties of porphyrins, enhanced characteristics of the ensemble are generated. This review article focuses on porphyrins bearing one or more peripheral transition metal complexes and discusses their potential applications in catalysis or biomedicine. Modulation of the electronic properties and intramolecular communication through coordination bond linkages in bis-porphyrin scaffolds is also presented., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)