Search

Chemically fueled chemical reaction networks (CRNs) are essential in controlling dissipative self-assembly. A key challenge in the field is to store chemical fuel-precursors or "pre-fuels" in the system that are converted into activating or deactivating fuels in a catalytically controlled CRN. In addition, real-time control over catalysis in a CRN by light is highly desirable, but so far not yet achieved. Here we show a catalytically driven CRN that is photoinitiated with 450 nm light, producing activated monomers that go on to perform transient self-assembly. Monomer activation proceeds via photoredox catalysis, converting the monomer alcohol groups into the corresponding aldehydes that self-assemble into large supramolecular fibers. Monomer deactivation is achieved by organometallic catalysis that relies on pre-fuel hydrolysis to release formate (i.e. the deactivating fuel). Additionally, irradiation with 305 nm light accelerates the release of formate by photo-uncaging the pre-fuel, leading to a factor of ca. 2 faster deactivation of the monomer. Overall, we show transient self-assembly upon visible light photoactivation, and tunable life-times by ultraviolet light., (© 2024 The Author(s). Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The chlorine radical is a strong HAT (Hydrogen Atom Transfer) agent that is very useful for the functionalization of C(sp 3 )-H bonds. Albeit highly attractive, its generation from the poorly oxidizable chloride ion mediated by an excited photoredox catalyst is a difficult task. We now report that 8R f8 -4CzIPN, an electron-deficient fluorous derivative of the benchmark 4CzIPN photoredox catalyst belonging to the donor-acceptor carbazole-cyanoarene family, is not only a better photooxidant than 4CzIPN, but also becomes an excellent host for the chloride ion. Combining these two properties ultimately makes the self-assembled 8R f8 -4CzIPN•Cl - dual catalyst highly reactive in redox-neutral Giese-type C(sp 3 )-H bond alkylation reactions promoted by the chlorine radical. Additionally, because of its fluorous character, the efficient separation/recovery of 8R f8 -4CzIPN could be envisioned., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Flavins and their alloxazine isomers are key chemical scaffolds for bioinspired electron transfer strategies. Their properties can be fine-tuned by functional groups, which must be introduced at an early stage of the synthesis as their aromatic ring is inert towards post-functionalization. We show that the introduction of a remote metal-binding redox site on alloxazine and flavin activates their aromatic ring towards direct C-H functionalization. Mechanistic studies are consistent with a synthetic sequence involving ground-state single electron transfer (SET) with an electrophilic source followed by radical-radical coupling. This unprecedented reactivity opens new opportunities in molecular editing of flavins by direct aromatic post-functionalization and the utility of the method is demonstrated with the site-selective C6 functionalization of alloxazine and flavin with a CF 3 group, Br or Cl, that can be further elaborated into OH and aryl for chemical diversification., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Two binuclear heteroleptic Cu I complexes, namely Cu-NIR1 and Cu-NIR2, bearing rigid chelating diphosphines and π-conjugated 2,5-di(pyridin-2-yl)thiazolo[5,4-d]thiazole as the bis-bidentate ligand are presented. The proposed dinuclearization strategy yields a large bathochromic shift of the emission when compared to the mononuclear counterparts (M1-M2) and enables shifting luminescence into the near-infrared (NIR) region in both solution and solid state, showing emission maximum at ca. 750 and 712 nm, respectively. The radiative process is assigned to an excited state with triplet metal-to-ligand charge transfer ( 3 MLCT) character as demonstrated by in-depth photophysical and computational investigation. Noteworthy, X-ray analysis of the binuclear complexes unravels two interligand π-π-stacking interactions yielding a doubly locked structure that disfavours flattening of the tetrahedral coordination around the Cu I centre in the excited state and maintain enhanced NIR luminescence. No such interaction is present in M1-M2. These findings prompt the successful use of Cu-NIR1 and Cu-NIR2 in NIR light-emitting electrochemical cells (LECs), which display electroluminescence maximum up to 756 nm and peak external quantum efficiency (EQE) of 0.43 %. Their suitability for the fabrication of white-emitting LECs is also demonstrated. To the best of our knowledge, these are the first examples of NIR electroluminescent devices based on earth-abundant Cu I emitters., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Hydrogen-bonded organic frameworks (HOFs) are ordered supramolecular solid structures, however, nothing much explored as centimetre-scale self-standing films. The fabrication of such crystals comprising self-supported films is challenging due to the limited flexibility and interaction of the crystals, and therefore studies on two-dimensional macrostructures of HOFs are limited to external supports. Herein, we introduce a novel chemical gradient strategy to fabricate a crystal-deposited HOF film on an in situ-formed covalent organic polymer film (Tam-Bdca-CGHOF). The fabricated film showed versatility in chemical bonding along its thickness from covalent to hydrogen-bonded network. The kinetic-controlled Tam-Bdca-CGHOF showed enhanced proton conductivity (8.3×10 -5  S cm -1 ) compared to its rapid kinetic analogue, Tam-Bdca-COP (2.1×10 -5  S cm -1 ), which signifies the advantage of bonding-engineering in the same system., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The redox activity of Cu ions bound to the amyloid-β (Aβ) peptide is implicated as a source of oxidative stress in the context of Alzheimer's disease. In order to explain the efficient redox cycling between Cu II -Aβ (distorted square-pyramidal) and Cu I -Aβ (digonal) resting states, the existence of a low-populated "in-between" state, prone to bind Cu in both oxidation states, has been postulated. Here, we exploited the partial X-ray induced photoreduction at 10 K, followed by a thermal relaxation at 200 K, to trap and characterize by X-ray Absorption Spectroscopy (XAS) a partially reduced Cu-Aβ 1-16 species different from the resting states. Remarkably, the XAS spectrum is well-fitted by a previously proposed model of the "in-between" state, hence providing the first direct spectroscopic characterization of an intermediate state. The present approach could be used to explore and identify the catalytic intermediates of other relevant metal complexes., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Complex non-equilibrium phase behaviors are a hallmark of natural self-assembling systems. Here we show how intricate phase transitions can be achieved through a chemically fueled reaction cycle to yield autonomous sol→gel→sol→gel→sol transitions. A relay of chemical transformations based on thiazinane metathesis leads to two consecutive transient gelations in a closed system. Within seconds of fuel addition to deactivated thiazinane monomers, an imine-based hydrogel forms that consists of fibrillar microspheres. This gel quickly loses its mechanical strength and forms a solution, from which a second aldehyde-based gel nucleates and remains stable for over one day. Overall, our reaction cycle gives rise to two consecutive re-entrant phase transitions without any experimental intervention., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

We report a unique vinyl coordination polymer (CP), [Zn(4-Fb) 2 (tkpvb)] n (1, 4-HFb=4-fluorobenzoic acid, tkpvb=1,2,4,5-tetrakis(4-pyridylvinyl)benzene) that undergoes a rare photopolymerization reaction to form a two-dimensional CP integrated with a one-dimensional linear organic polymer. Upon light irradiation at different wavelengths, 1 exhibits an unprecedented phenomenon of photoinduced nonlinear lattice expansion. 1 can be uniformly dispersed in polyvinyl alcohol (PVA) to form the composite film of 1-PVA. When this film is exposed to UV light, internal minute stresses within crystallites are released by lattice expansion, resulting in a variety of photopolymerization-driven macroscopic mechanical motions. The findings provide new insights into the conversion of small lattice expansions of CPs into macroscopic mechanical motions based on photopolymerization reactions, which can promote the development of CPs-based smart photoactuators in the burgeoning field of microrobotics., (© 2023 Wiley-VCH GmbH.)

With fast (de)coordination kinetics, the smallest and the lightest proton stands out as the most ideal charge carrier for aqueous Zn-organic batteries (ZOBs). Hydrogen-bonding networks with rapid Grotthuss proton conduction is particularly suitable for organic cathodes, yet not reported. We report the supramolecular self-assembly of cyanuric acid and 1,3,5-triazine-2,4,6-triamine into organic superstructures through in-plane H-bonds and out-of-plane π-π interaction. The supramolecular superstructures exhibit highly stable lock-and-key H-bonding networks with an ultralow activation energy for protonation (0.09 eV vs. 0.25 eV of zincification). Then, high-kinetics H + coordination is prior to Zn 2+ into protophilic C=O sites via a two-step nine-electron reaction. The assembled ZOBs show high-rate capability (135 mAh g -1 at 150 A g -1 ), high energy density (267 Wh kg -1 cathode ) and ultra-long life (50 000 cycles at 10 A g -1 ), becoming the state-of-the-art ZOBs in comprehensive performances., (© 2023 Wiley-VCH GmbH.)

A β-cyclodextrin-based diphosphane with metal-confining properties was efficiently synthesized thanks to an unprecedented Smiles-like rearrangement of diphenyl-(2-phosphanylphenyl)phosphane in the presence of excess n-BuLi. The cis-chelating bidentate ligand is capable of forming very stable heteroleptic [Cu(NN)(PP)] + complexes in which a metal-bound diimine ligand (bpy, phen, or mmp) is located within the cyclodextrin cavity. As a result of ligand encapsulation, flattening of the metal tetrahedral geometry in the excited state is disfavored, thereby resulting in enhanced luminescent properties., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Highly active and stable cathodes are critical for aqueous Zn-organic batteries with high capacity, fast redox kinetics, and long life. We herein report para-, meta-, and ortho-dinitrobenzene (p-, m-, and o-DB) containing two successive two-electron processes, as cathode materials to boost the battery performance. Theoretical and experimental studies reveal that nitro constitutional isomerism is key to zincophilic activity and redox kinetics. p-DB hosted in carbon nanoflower harvests a high capacity of 402 mAh g -1 and a superior stability up to 25 000 cycles at 5 A g -1 , giving a Zn-organic battery with a high energy density of 230 Wh kg -1 . An anionic co-insertion charge storage mechanism is proposed, entailing a two-step (de)coordination of Zn(CF 3 SO 3 ) + with nitro oxygen. Besides, dinitrobenzene can be electrochemically optimized by side group regulation via implanting electron-withdrawing motifs. This work opens a new window to design multielectron nitroaromatics for Zn-organic batteries., (© 2022 Wiley-VCH GmbH.)

Thiacalix[4]arenes have emerged as a family of macrocyclic ligands to protect metal nanoparticles, but it remains a great challenge to solve the mystery of their structures at the atomic level, especially for those larger than 2 nm. Here, we report the largest known mixed-valence silver nanocluster [Ag 155 (CyS) 40 (TC4A) 5 Cl 2 ] (Ag155) protected by deprotonated cyclohexanethiol (CySH) and macrocyclic ligand p-tert-butylthiacalix[4]arene (H 4 TC4A). Its single-crystal structure consists of a metallic core of four concentric shells, Ag 13 @Ag 42 @Ag 30 @Ag 70 , lined with a organic skin of 40CyS - and 5TC4A 4- and 2Cl - . Ag155 manifests an unusual pseudo-5-fold symmetry dictated by the intrinsic metal atom packing and the regioselective distribution of mixed protective ligands. This work not only reveals a macrocyclic ligand effect on the formation of a large silver nanocluster, but also provides a new structural archetype for comprehensively perceiving their interface and metal kernel structures., (© 2022 Wiley-VCH GmbH.)

The salts {[Ln 2 Ln*(Hhmq) 3 (OAc) 3 (hfac) 2 ] + [Ln*(hfac) 3 (OAc)(MeOH)] - } (Hhmq=2-methanolquinolin-8-oxide, hfac=hexafluoroacetylacetonate; Ln, Ln*=Er, Gd, Yb) feature a discrete heteronuclear cation consisting of two types of lanthanide atoms. The quinolinoxy O-atom serves as a μ 2 -bridge to two Ln atoms and as a μ 3 -bridge to all three atoms, with metal⋅⋅⋅metal distances being around 3.7 Å. For 1 ([Yb 2 Er] + ), near-infrared downshifted luminescence is switched to competitive upconversion luminescence upon irradiation by a 980 nm laser under an extremely low excitation power (0.288 W cm -2 ) through introduction of fluoride ions. The stability of 1 after addition of fluoride was confirmed by powder X-ray diffraction and multistage mass spectrometry, associated with the 1 H NMR of 6 ([La 2 Eu] + ). More importantly, the at least 20-fold enhancement of the quantum yield in non-deuterated solvents at room temperature under low power densities (2 W cm -2 ) is the highest among the few molecular examples reported., (© 2021 Wiley-VCH GmbH.)

Chalcogen bonding results from non-covalent interactions occurring between electrodeficient chalcogen atoms and Lewis bases. Among the chalcogens, tellurium is the strongest Lewis acid, but Te-based compounds are scarcely used as organocatalysts. For the first time, telluronium cations demonstrated impressive catalytic properties at low loadings in three benchmark reactions: the Friedel-Crafts bromination of anisole, the bromolactonization of ω-unsaturated carboxylic acids and the aza-Diels-Alder between Danishefsky's diene and imines. The ability of telluronium cations to interact with a Lewis base through chalcogen bonding was demonstrated on the basis of multi-nuclear ( 17 O, 31 P, and 125 Te) NMR analysis and DFT calculations., (© 2021 Wiley-VCH GmbH.)

The employment of the hexyl-substituted anion [HexCB 11 Cl 11 ] - allowed the synthesis of a Zn II species, Zn[HexCB 11 Cl 11 ] 2 , 3, in which the Zn 2+ cation is only weakly coordinated to two carborate counterions and that is soluble in low polarity organic solvents such as bromobenzene. DOSY NMR studies show the facile displacement of at least one of the counterions, and this near nakedness of the cation results in high catalytic activity in the hydrosilylation of 1-hexene and 1-methyl-1cyclohexene. Fluoride ion affinity (FIA) calculations reveal a solution Lewis acidity of 3 (FIA=262.1 kJ mol -1 ) that is higher than that of the landmark Lewis acid B(C 6 F 5 ) 3 (FIA=220.5 kJ mol -1 ). This high Lewis acidity leads to a high activity in catalytic CO 2 and Ph 2 CO reduction by Et 3 SiH and hydrogenation of 1,1-diphenylethylene using 1,4-cyclohexadiene as the hydrogen source. Compound 3 was characterized by multinuclear NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, and DFT studies., (© 2020 Wiley-VCH GmbH.)

Tuning the dihedral angle (DA) of axially chiral compounds can impact biological activity, catalyst efficiency, molecular motor performance, or chiroptical properties. Herein, we report gradual, controlled, and reversible changes in molecular conformation of a covalently linked binaphthyl moiety within a 3D polymeric network by application of a macroscopic stretching force. We managed direct observation of DA changes by measuring the circular dichroism signal of an optically pure BINOL-crosslinked elastomer network. Stretching the elastomer resulted in a widening of the DA between naphthyl rings when the BINOL was doubly grafted to the elastomer network; no effect was observed when a single naphthyl ring of the BINOL was grafted to the elastomer network. We have determined that ca. 170 % extension of the elastomers led to the transfer of a mechanical force to the BINOL moiety of 2.5 kcal mol -1  Å -1 (ca. 175 pN) in magnitude and results in the opening of the DA of BINOL up to 130°., (© 2020 Wiley-VCH GmbH.)

A bis-acridinium cyclophane incorporating switchable acridinium moieties linked by a 3,5-dipyridylanisole spacer was studied as a multi-responsive host for polycyclic aromatic hydrocarbon guests. Complexation of perylene was shown to be the most effective and was characterized in particular by a charge-transfer band as signal output. Effective catch and release of the guest was triggered by both chemical (proton/hydroxide) and redox stimuli. Moreover, the dicationic host was also easily switched between organic and perfluorocarbon phases for applications related to the enrichment of perylene from a mixture of polycyclic aromatic hydrocarbons., (© 2020 Wiley-VCH GmbH.)

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have attracted enormous attention in recent years. Recently, MOF@COF are emerging as hybrid architectures combining the unique features of the individual components to enable the generation of materials displaying novel physicochemical properties. Herein we report an unprecedented use of aza-Diels-Alder cycloaddition reaction as post-synthetic modification of MOF@COF-LZU1, to generate aza-MOFs@COFs hybrid porous materials with extended π-delocalization. A a proof-of-concept, the obtained aza-MOFs@COFs is used as electrode in supercapacitors displaying specific capacitance of 20.35 μF cm -2 and high volumetric energy density of 1.16 F cm -3 . Our approach of post-synthetic modification of MOFs@COFs hybrids implement rational design for the synthesis of functional porous materials and expands the plethora of promising application of MOFs@COFs hybrid porous materials in energy storage applications., (© 2020 Wiley-VCH GmbH.)

To activate electronic and optical functions of the redox-active metal-organic framework, (Me 2 NH 2 )[In III (TTFTB)]⋅0.7 C 2 H 5 OH⋅DMF (Me 2 NH 2 @1, TTFTB=tetrathiafulvalene-tetrabenzoate, DMF=N,N-dimethylformamide), has been exchanged by tetrathiafulvalenium (TTF .+ ) and N,N'-dimethyl-4,4'-bipyridinium (MV 2+ ). These cations provide electron carriers and photosensitivity. The exchange retains the crystallinity allowing single-crystal to single-crystal post-synthetic transformation to TTF@1 and MV@1. Both TTF .+ and MV 2+ enhance the electrical conductivity by a factor of 10 2 and the visible light induced photocurrent by 4 and 28 times, respectively. EPR evidences synergetic effect involving charge transfer between the framework redox-active TTFTB bridges and MV 2+ . The results demonstrate that functionalization of MOF by cation exchange without perturbing the crystallinity extends possibilities to achieve switchable materials., (© 2020 Wiley-VCH GmbH.)

Autocatalysis and self-assembly are key processes in developmental biology and are involved in the emergence of life. In the last decade both of these features were extensively investigated by chemists with the final goal to design synthetic living systems. Herein, we describe the autonomous growth of a self-assembled soft material, that is, a supramolecular hydrogel, able to sustain its own formation through an autocatalytic mechanism that is not based on any template effect and emerges from a peptide (hydrogelator) self-assembly. A domino sequence of events starts from an enzymatically triggered peptide generation followed by self-assembly into catalytic nanofibers that induce and amplify their production over time, resulting in a 3D hydrogel network. A cascade is initiated by traces (10 -18  m) of a trigger enzyme, which can be localized allowing for a spatial resolution of this autocatalytic buildup of hydrogel growth, an essential condition on the route towards further cell-mimic designs., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The in situ tracking of the pyrolysis of a binary molecular cluster [Zn 7 (μ 3 -CH 3 O) 6 (L) 6 ][ZnLCl 2 ] 2 is presented with one brucite disk and two mononuclear fragments (L=mmimp: 2-methoxy-6-((methylimino)-methyl)phenolate) to porous carbon using TG-MS from 30 to 900 °C. Following up the spilled gas product during the decomposed reaction of zinc cluster along the temperature rising, and in conjunction with XRD, SEM, BET and other materials characterization, where three key steps were observed: 1) cleavage of the bulky external ligand; 2) reduction of ZnO and 3) volatilization of Zn. The real-time-dependent phase-sequential evolution of the remaining products and the processing of pore forming template transformation are proposed simultaneously. The porous carbon structure featuring a uniform nano-sized pore distribution synthesized at 900 °C with the highest surface area of 1644 m 2  g -1 and pore volume of 0.926 cm 3  g -1 exhibits the best known capacitance of 662 F g -1 at 0.5 A g -1 ., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Capture and release of peptides is often a critical operation in the pathway to discovering materials with novel functions. However, the best methods for efficient capture impede facile release. To overcome this challenge, we report linkers based on secondary amino alcohols for the release of peptides after capture. These amino alcohols are based on serine (seramox) or isoserine (isoseramox) and can be incorporated into peptides during solid-phase peptide synthesis through reductive amination. Both linkers are quantitatively cleaved within minutes under NaIO 4 treatment. Cleavage of isoseramox produced a native peptide N-terminus. This linker also showed broad substrate compatibility; incorporation into a synthetic peptide library resulted in the identification of all sequences by nanoLC-MS/MS. The linkers are cell compatible; a cell-penetrating peptide that contained this linker was efficiently captured and identified after uptake into cells. These findings suggest that such secondary amino alcohol based linkers might be suitable tools for peptide-discovery platforms., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Copper complexes are of medicinal and biological interest, including as anticancer drugs designed to cleave intracellular biomolecules by O 2 activation. To exhibit such activity, the copper complex must be redox active and resistant to dissociation. Metallothioneins (MTs) and glutathione (GSH) are abundant in the cytosol and nucleus. Because they are thiol-rich reducing molecules with high Cu I affinity, they are potential competitors for a copper ion bound in a copper drug. Herein, we report the investigation of a panel of Cu I /Cu II complexes often used as drugs, with diverse coordination chemistries and redox potentials. We evaluated their catalytic activity in ascorbate oxidation based on redox cycling between Cu I and Cu II , as well as their resistance to dissociation or inactivation under cytosolically relevant concentrations of GSH and MT. O 2 -activating Cu I /Cu II complexes for cytosolic/nuclear targets are generally not stable against the GSH/MT system, which creates a challenge for their future design., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Adenosylhopane is a crucial intermediate in the biosynthesis of bacteriohopanepolyols, which are widespread prokaryotic membrane lipids. Herein, it is demonstrated that reconstituted HpnH, a putative radical S-adenosyl-l-methionine (SAM) enzyme, commonly encoded in the hopanoid biosynthetic gene cluster, converts diploptene into adenosylhopane in the presence of SAM, flavodoxin, flavodoxin reductase, and NADPH. NMR spectra of the enzymatic reaction product were identical to those of synthetic (22R)-adenosylhopane, indicating that HpnH catalyzes stereoselective C-C formation between C29 of diploptene and C5' of 5'-deoxyadenosine. Further, the HpnH reaction in D 2 O-containing buffer revealed that a D atom was incorporated at the C22 position of adenosylhopane. Based on these results, we propose a radical addition reaction mechanism catalyzed by HpnH for the formation of the C 35 bacteriohopane skeleton., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Inspired by biology, one current goal in supramolecular chemistry is to control the emergence of new functionalities arising from the self-assembly of molecules. In particular, some peptides can self-assemble and generate exceptionally catalytically active fibrous networks able to underpin hydrogels. Unfortunately, the mechanical fragility of these materials is incompatible with process developments, relaying this exciting field to academic curiosity. Here, we show that this drawback can be circumvented by enzyme-assisted self-assembly of peptides initiated at the walls of a supporting porous material. We applied this strategy to grow an esterase-like catalytically active supramolecular hydrogel (CASH) in an open-cell polymer foam, filling the whole interior space. Our supported CASH material is highly efficient towards inactivated esters and enables the kinetic resolution of racemates. This hybrid material is robust enough to be used in continuous flow reactors, and is reusable and stable over months., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Photoreactive olefinic species are incorporated into a metal-organic framework (MOF), [Zn(bdc)(3-F-spy)] (1). Single crystals of 1 are shown to undergo three types of photomechanical macroscopic deformation upon illumination by UV light. To demonstrate the practical potential of this system, the inclusion of 1 in a PVA (polyvinyl alcohol) composite membrane, by exploiting hydrogen-bonding interactions, is presented. Using this composite membrane, the amplification of mechanical stress to achieve macroscopic actuation behavior is demonstrated. These results pave the way for the generation of MOF-based soft photoactuators that produce clearly defined mechanical responses upon irradiation with light. Such systems are anticipated to have considerable potential in photomechanical energy harvesting and conversion systems., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A composite material, {[Fe(L)(TPPE) 0.5 ]⋅3 CH 3 OH} n , has been constructed by integrating the spin-crossover (SCO) subunit Fe II {diethyl(E,E)-2,2'-[1,2-phenyl-bis(iminomethylidyne)]bis(3-oxobutanoate)-(2-)-N,N',O 3 ,O 3 '} and the highly luminescent connector 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)-ethene. Its structure contains four staggered 4×4 layers and intercalated methanol. The packing is dominated by considerable H-bonds either between adjacent layers and between layers and guests. A crystal-structure transformation was detected upon removal of the guest molecules. The SCO transition of the solvated crystals is centered at ca. 215 K with a non-symmetrical hysteresis of 25 K wide, and the desolvated [Fe(L)(TPPE) 0.5 ] n exhibits gradual SCO without hysteresis. Intriguingly, the intensity of the fluorescence at 460 nm for the latter is maximized at the SCO transition. The energy transfer between luminescent and SCO entities is achievable as confirmed by theoretical calculations., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ultrathin metal-organic framework (MOF) nanosheets (NSs) offer potential for many applications, but the synthetic strategies are largely limited to top-down, low-yield exfoliation methods. Herein, Ni-M-MOF (M=Fe, Al, Co, Mn, Zn, and Cd) NSs are reported with a thickness of only several atomic layers, prepared by a large-scale, bottom-up solvothermal method. The solvent mixture of N,N-dimethylacetamide and water plays key role in controlling the formation of these two-dimensional MOF NSs. The MOF NSs can be directly used as efficient electrocatalysts for the oxygen evolution reaction, in which the Ni-Fe-MOF NSs deliver a current density of 10 mA cm -2 at a low overpotential of 221 mV with a small Tafel slope of 56.0 mV dec -1 , and exhibit excellent stability for at least 20 h without obvious activity decay. Density functional theory calculations on the energy barriers for OER occurring at different metal sites confirm that Fe is the active site for OER at Ni-Fe-MOF NSs., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction of {(HNEt 3 ) 2 [Ag 10 (tBuC 6 H 4 S) 12 ]} n , Ag 2 O, Na 2 MoO 4 , and m-methoxybenzoic acid (Hmbc) in CH 3 OH/CH 2 Cl 2 led to yellow crystals of [Ag 4 S 4 (MoO 4 ) 5 @Ag 66 ] (SD/Ag70b; SD=SunDi) only, while in the presence of DMF, additional dark-red crystals of [Ag 10 @ (MoO 4 ) 7 @Ag 60 ] (SD/Ag70a) were obtained. SD/Ag70b consists of five MoO 4 2- ions wrapped by a shell of 66 Ag atoms, while SD/Ag70a contains a rare Ag 10 kernel consisting of five tetrahedra sharing faces and edges, surrounded by seven MoO 4 2- ions enclosed in a shell of 60 Ag atoms. The formation of the Ag 10 kernel originates from a reduction reaction during the self-assembly process that involves DMF. This work provides the structural information of a unique Ag 10 kernel (five fused Ag 4 tetrahedra) and paves an avenue to trap elusive silver species with hierarchical multi-shell silver nanocluster assemblies with the help of anion templates., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two pure silver nanoparticles (Ag 210 ( i PrPhS) 71 (Ph 3 P) 5 Cl and Ag 211 ( i PrPhS) 71 (Ph 3 P) 6 Cl labeled as SD/Ag210 and SD/Ag211 (SD=SunDi), were found to co-crystallize in forming compound 1. Single-crystal X-ray diffraction (SCXRD) revealed that they differ by only one Ag(PPh 3 ). Their four-shell nanoparticles consist of three pure Ag metal shells (Ag 19 @Ag 52 @Ag 45 ) shielded by a silver-organic Ag 89 ( i PrPhS) 71 Cl[Ag(Ph 3 P)] n outermost shell. The number (n) of Ag(Ph 3 P) is five for SD/Ag210 and six for SD/Ag211. The pseudo-fivefold symmetric Ag nanoparticles exhibit surface plasmon absorption similar to a true metallic state but at the nanoscale. This work exemplifies the important effects of phosphine in stabilizing large silver nanoparticles; and offers a platform to investigate the origin of differences in nanoscale metal materials, even differing by only one metal atom; it also sheds light on the regioselective binding of auxiliary Ph 3 P on the surface of silver nanoparticles., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Metallotropism of the M[N(SiMe 3 ) 2 ] 2 metal fragment in the tautomeric system IA R ⇌AC R involving imidazolium salts/N-heterocyclic carbenes with remote aminide/amine substituents, respectively, is manifested by its C NHC carbophilicity (R=tBu, M=Co, Fe) or NR aminido nitrogenophilicity (R=Cy, M=Co, Fe; R=Mes, M=Fe) and has been rationalized on the basis of steric and electronic effects. The thermolysis products of the [M{N(SiMe 3 ) 2 } 2 ]/ IA R ⇌AC R system are also substituent-dependent, leading to a rearranged aminide-functionalized aNHC Co 2 complex of an unprecedented type or to ring-opened metallaketenimines; they are postulated to originate from different metalloisomers. The results are interpreted on the basis of the X-ray diffraction analysis of 11 new compounds., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A frustrated Lewis pair (FLP) system was obtained by confinement of the Lewis base partner, a Verkade's superbase, in a molecular cavity. Whereas the model superbase lacking cavity displayed no catalytic activity in Morita-Baylis-Hillman (MBH) reactions, when associated to titanium (IV) chloride, the encaged superbase turns out to be an efficient catalyst under the same conditions. The crucial role of the endohedral functionalized cage on catalytic performance was further demonstrated by the fact that model superbases with bulky substituents were much less efficient to produce active catalysts, as well as by inhibition and substrate selection experiments. 31 P NMR spectroscopy and mass spectrometry experiments evidenced that no interaction between the Lewis acidic and basic partners occurred when the superbase was capped by a cycloveratrylene (CTV) unit, thus creating a true FLP active system., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Continual progress has been achieved in information technology through unrelenting miniaturisation of the single memory bit in integrated ferromagnetic, ferroelectric, optical, and related circuits. However, as miniaturisation approaches its theoretical limit, new memory materials are being sought. Herein, we report a unique material exhibiting single-molecule electric polarisation switching that can operate above room temperature. The phenomenon occurs in a Preyssler-type polyoxometalate (POM) cluster we call a single-molecule electret (SME). It exhibits all the characteristics of ferroelectricity but without long-range dipole ordering. The SME affords bi-stability as a result of the two potential positions of localisation of a Tb 3+ ion trapped in the POM, resulting in extremely slow relaxation of the polarisation and electric hysteresis with high spontaneous polarisation and coercive electric fields. Our findings suggest that SMEs can potentially be applied to ultrahigh-density memory and other molecular-level electronic devices operating above room temperature., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Regioselective photodimerization of trans-4-styrylpyridine (4-spy) derivatives is performed using pseudorotaxane-like Zn-based metal organic frameworks MOFs as templates. The formation of rctt-HT (head-to-tail) dimers is achieved by confining pairs of coordinated 4-spy derivative ligands within hexagonal windows and then irradiating them with UV light. It is also possible to achieve a photodimerization reaction where two different substituted 4-spy ligands are included in such a MOF material. The ether bond formation is employed to protect the sensitive -OH group of HO-spy and the methyl group of CH 3 O-spy is subsequently removed after the formation of cyclobutane derivative in the CH 3 O-spy-based MOF. Introducing substituents at the 2- or 3-position of the phenyl group of 4-spy does not significantly affect the rate of the dimerization process except in the case of the strongly electron-withdrawing nitro group where the rate is significantly decreased. These results are in striking contrast to the mixtures of photoproducts and low yields obtained by untemplated photodimerization in organic solvents., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In search of magneto-optic materials, the mononuclear compounds Ln III (depma)(NO 3 ) 3 (hmpa) 2 (Ln=Dy, Gd) were synthesized. The anthracene moieties undergo [4+4] dimerization when irradiated at 365 nm without loss of crystallinity. The Dy compound switches from a single-ion to a single-molecule magnet with doubling of the spin reversal barrier energy and from yellow-green to blue-white emission. The dimerization is reversed by heating at 100 °C or partially on light irradiating at 254 nm. The results suggest that lanthanide phosphonates with anthracene are promising smart materials displaying synergistic magneto-optic property., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein we disclose the synthesis of original chiral scaffolds-ortho-orientated terphenyls presenting two atropisomeric Ar-Ar axes. These unusual structures were built up by using the C-H activation approach, and remarkably, both chiral axes were controlled with excellent stereoselectivity in a single transformation. During the reaction, not only does atroposelective functionalization of a biaryl precursor occur to establish one stereogenic axis, but an unprecedented atropo-stereoselective C-H arylation also takes place to generate the second stereogenic element. These enantiomerically pure ortho-terphenyls show an original tridimensional structure and thus constitute a unique foundation for building up a library of enantiomerically pure bidentate ligands, such as the new ligands S/N-Biax and diphosphine BiaxPhos., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The imidazolium chloride [C 3 H 3 N(C 3 H 6 NMe 2 )N{C(Me)(=NDipp)}]Cl (1; Dipp=2,6-diisopropyl phenyl), a potential precursor to a tritopic N imine C NHC N amine pincer-type ligand, reacted with [Ni(cod) 2 ] to give the Ni I -Ni I complex 2, which contains a rare cod-derived η 3 -allyl-type bridging ligand. The implied intermediate formation of a nickel hydride through oxidative addition of the imidazolium C-H bond did not occur with the symmetrical imidazolium chloride [C 3 H 3 N 2 {C(Me)(=NDipp)} 2 ]Cl (3). Instead, a Ni-C(sp 3 ) bond was formed, leading to the neutral N imine CHN imine pincer-type complex Ni[C 3 H 3 N 2 {C(Me)(=NDipp)} 2 ]Cl (4). Theoretical studies showed that this highly unusual feature in nickel NHC chemistry is due to steric constraints induced by the N substituents, which prevent Ni-H bond formation. Remarkably, ethylene inserted into the C(sp 3 )-H bond of 4 without nickel hydride formation, thus suggesting new pathways for the alkylation of non-activated C-H bonds., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Multiferroic materials coupling ferroelasticity and ferromagnetism show strong magnetoelastic effects as magnetization is induced by mechanical stress or alternately strain induced by applying a magnetic field. These effects were reported for inorganic multiferroics such as LaCo x Sr 1-x O 3 . (C 6 H 5 C 2 H 4 NH 3 ) 2 Fe II Cl 4 is the first example of an organic-inorganic perovskite to exhibit such effects below the canted antiferromagnetism at T C =98 K and ferroelasticity at T C =433 K. This is shown by switching the magnetic hysteresis on and off by uniaxial pressure through the strong coupling of the magnetic and elastic domains. The spin-canting direction was controlled by mechanical stress in the heating and cooling cycles. This unique observation gives additional impetus in the search for coupled hysteretic effect in organic-inorganic multiferroics., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The assembly sequence of the coordination cluster [Zn5 (H2 L(n) )6 ](NO3 )4 ]⋅8 H2 O⋅2 CH3 OH (Zn5 , H3 L(n) =(1,2-bis(benzo[d]imidazol-2-yl)-ethenol) involves in situ dehydration of 1,2-bis(benzo[d]imidazol-2-yl)-1,2-ethanediol (H4 L) through the formation of the [Zn(H3 L)2 ](+) monomer, dimerization to [Zn2 (H3 L)2 ](+) , dehydration of the ligand to [Zn2 (H2 L(n) )2 ](+) , and the final formation of the pentanuclear cluster. The cluster has the following special characteristics: 1) high stability in both refluxing 37 % HCl and 27 % NH3 , 2) low cytotoxicity, and 3) pH-sensitive fluorescence in the visible-to-near-infrared (Vis/NIR) region in the solid state and in solution. We have applied it as a fluorescent probe both in vivo and in vitro. Its H-bonding ability is the key to its affinity and selectivity for imaging lysosomes in HeLa cells and tumors in male BALB/C mice. It provides a new type of sensitive and biocompatible fluorescent probe for detecting small tumors (13.5 mm(3) )., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Valuable 1-azabicycloalkane derivatives have been synthesized through a novel gold(I)-catalyzed desulfonylative cyclization strategy. An ammoniumation reaction of ynones substituted at the 1-position with an N-sulfonyl azacycle took place in the presence of a gold cation by intramolecular cyclization of the disubstituted sulfonamide moiety onto the triple bond. Depending on the size of the heterocyclic ring and substitution of the substrates, two unprecedented forms of nucleophilic attack on the sulfonyl group were exploited, that is, a N-desulfonylation in the presence of an external protic O nucleophile (37-87 %, 10 examples) and a unique N-to-O 1,5-sulfonyl migration (60-98 %, 9 examples)., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Cyclization of silylenolether-ynesulfonamides proceeds at ambient temperature under mild reaction conditions under silver catalysis. Bridged compounds were obtained exclusively through 7-exo-dig reactions. The protocol is applicable to a wide range of substrates, thus leading to azabicyclic frameworks., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A mononuclear bis(NHC)/Au(I) (NHC=N-heterocyclic carbene) cationic complex with a rigid bis(phosphane)-functionalized NHC ligand (PC(NHC)P) was used to construct linear Au3 and Ag2 Au arrays, a Au5 cluster with two intersecting crosslike Au3 arrays, and an unprecedented Cu6 complex with two parallel Cu3 arrays. The impact of metallophilic interactions on photoluminescence was studied experimentally., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A contractile dendritic motional device is reported where metal ions with biological importance--Ca(2+) (the main regulatory and signaling species of the natural muscles), Mg(2+), and Zn(2+)--initiate two kinds of motional functions. The first motional function is the metal-ion-induced contraction of a linear strand into a Z-shaped dinuclear complex, and the second one is the change of the height of Z-shaped complexes via transmetalation. By means of the pH-dependent counterligand tren, the two motional features of the machine can depend on alternate additions of acid and base. An optical response is associated with the conversion of the linear form (which is yellow) into the metalated Z-shaped one (which is red)., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The relative lability and transmetallation aptitude of trialkylphosphine and NHC donors, integrated in semi-rigid hybrid ligands attached to [Ag4Br4] pseudo-cubanes, lies in favor of the NHC and is used to selectively access unprecedented NHC complexes with heterobimetallic cores, such as Ag-Cu (4(Cy)) and Ag-Ir (5(tBu)). These can be viewed as an arrested state before the full transmetallation of both donors, which gives the homodinuclear Cu (3(Cy)) and Ir (6(Cy)) complexes. The observed NHC transmetallation aptitude and reactivity urges caution in the common notion that views the NHC as a universal spectator., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The LytB/IspH protein catalyzes the last step of the methylerythritol phosphate (MEP) pathway which is used for the biosynthesis of essential terpenoids in most pathogenic bacteria. Therefore, the MEP pathway is a target for the development of new antimicrobial agents as it is essential for microorganisms, yet absent in humans. Substrate-free LytB has a special [4Fe-4S](2+) cluster with a yet unsolved structure. This motivated us to use synchrotron-based nuclear resonance vibrational spectroscopy (NRVS) in combination with quantum chemical-molecular mechanical (QM/MM) calculations to gain more insight into the structure of substrate-free LytB. The apical iron atom of the [4Fe-4S](2+) is clearly linked to three water molecules. We additionally present NRVS data of LytB bound to its natural substrate, (E)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMBPP) and to the inhibitors (E)-4-amino-3-methylbut-2-en-1-yl diphosphate and (E)-4-mercapto-3-methylbut-2-en-1-yl diphosphate., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Despite significant advances in foldamer chemistry, tailored delivery systems based on foldamer architectures, which provide a high level of control over secondary structure, are curiously rare among non-viral technologies for transporting nucleic acids into cells. A potent pH-responsive, bioreducible cell-penetrating foldamer (CPF) was developed through covalent dimerization of a short (8-mer) amphipathic oligourea sequence bearing histidine-type units. This CPF exhibits a high capacity to assemble with pDNA and mediates efficient delivery of nucleic acids into the cell. Furthermore, it does not adversely affect cellular viability and was shown to compare favorably with a cognate peptide transfection agent based on His-rich sequences., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ground-state molecular vibrations can be hybridized through strong coupling with the vacuum field of a cavity optical mode in the infrared region, leading to the formation of two new coherent vibro-polariton states. The spontaneous Raman scattering from such hybridized light-matter states was studied, showing that the collective Rabi splitting occurs at the level of a single selected bond. Moreover, the coherent nature of the vibro-polariton states boosts the Raman scattering cross-section by two to three orders of magnitude, revealing a new enhancement mechanism as a result of vibrational strong coupling. This observation has fundamental consequences for the understanding of light-molecule strong coupling and for molecular science., (© 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.)

Two-photon photodynamic therapy is a promising therapeutic method which requires the development of sensitizers with efficient two-photon absorption and singlet-oxygen generation. Reported here are two new diketopyrrolopyrrole-porphyrin conjugates as robust two-photon absorbing dyes with high two-photon absorption cross-sections within the therapeutic window. Furthermore, for the first time the singlet-oxygen generation efficiency of diketopyrrolopyrrole-containing systems is investigated. A preliminary study on cell culture showed efficient two-photon induced phototoxicity., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hemichelation is emerging as a new mode of coordination where non-covalent interactions crucially contribute to the cohesion of electron-unsaturated organometallic complexes. This study discloses an unprecedented demonstration of this concept to a Group 9 metal, that is, Rh(I). The syntheses of new 14-electron Rh(I) complexes were achieved by choosing the anti-[(η(6):η(6)-fluorenyl){Cr(CO)3}2] anion as the ambiphilic hemichelating ligand, which was treated with [{Rh(nbd)Cl}2] (nbd=norbornadiene) and [{Rh(CO)2Cl}2]. The new T-shaped Rh(I) hemichelates were characterized by analytical and structural methods. Investigations using the methods of the DFT and electron-density topology analysis (NCI region analysis, QTAIM theory) confirmed the closed-shell, non-covalent and attractive characters of the interaction between the Rh(I) center and the proximal Cr(CO)3 moiety. This study shows that, by appropriate tuning of the electronic properties of the ambiphilic ligand, truly coordination-unsaturated Rh(I) complexes can be synthesized in a manageable form., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)