Multifunctional Supramolecular Gels with Strong Mechanical Properties Formed by Self-Assembly of Polyoxometalate-Based Coordination Polymers.

Metallogels built in a bottom-up approach by metal coordination and supramolecular interactions have important potential for the elaboration of smart materials. In this context, we present here the formation of supramolecular coordination polymers driven by the complexation of cobalt(II) or zinc(II) ions with polyoxometalate-based hybrids displaying two terpyridine ligands in a linear arrangement. Thanks to the electrostatic interactions between the polyoxometalate cores and metal nodes, the polymer chains self-assemble into fibers that physically cross-link to form gels above a critical concentration.

Cyclometalated luminescent platinum(II) complexes of dissymmetrical 2,2':4',2''-terpyridine and its self-assembled dimer presenting Pt-Ag dative bonds.

A series of cyclometalated (N^C^N) Pt(II)-platinum complexes featuring a terpyridine ligand with a non-coordinating nitrogen atom and a Pt-C bond was synthesized. In the presence of Ag, the bis(isonitrile)Pt(II) complex formed a remarkable self-assembled helicoidal dimer stabilized by coordination of Ag(I) and metallophilic Pt-Ag interactions. Its assembly was observed in the solid state and maintained in solution.

Divergent Fe-Mediated C-H Activation Paths Driven by Alkali Cations.

The association of the ferrous complex FeCl(dmpe) () with alkali bases M(hmds) (M = Li, Na, K) proves to be an efficient platform for the activation of Ar-H bonds. Two mechanisms can be observed, leading to either Ar-Fe species by deprotonative ferration or hydrido species Ar-Fe-H by oxidative addition of transient Fe(dmpe) generated by reduction of . Importantly, the nature of the alkali cation in M(hmds) has a strong influence on the preferred path.

Multi-Electron Visible Light Photoaccumulation on a Dipyridylamine Copper(II)-Polyoxometalate Conjugate Applied to Photocatalytic Generation of CF Radicals.

This article describes the synthesis and characterization of an organic-inorganic hybrid polyoxometalate functionalized by a short link with a tripodal N-based ligand and its copper complex. Upon visible light irradiation, the latter is able to store up to three reducing equivalents. The locus of the reduction is discussed based on physicochemical measurements and DFT calculations.

Precisely Designed Difunctionalized Cyclodextrin Produces a Solid-State Organic Porous Hierarchical Supramolecular Assembly.

Regioselective di-functionalization of a cyclodextrin allows hydrophobic domains to be directed in a geometrically controlled manner. This controlled orientation ultimately gives access to an original hierarchical assembly in the solid state. This assembly spans over three levels of hierarchy which are governed by synergistic host-guest inclusions, directed hydrophobic effect and hydrogen bonding.

Molecular Magnetic Materials Based on {Co (Tp*)(CN) } Cyanidometallate: Combined Magnetic, Structural and Co NMR Study.

The cyanidocobaltate of formula fac-PPh [Co ( Tp)(CN) ] ⋅ CH CN (1) has been used as a metalloligand to prepare polynuclear magnetic complexes ( Tp=hydrotris(3,5-dimethylpyrazol-1-yl)borate). The association of 1 with in situ prepared [Fe (bik) (MeCN) ](OTf) (bik=bis(1-methylimidazol-2-yl)ketone) leads to a molecular square of formula {[Co {( Tp)}(CN) ] [Fe (bik) ] }(OTf)  ⋅ 4MeCN ⋅ 2H O (2), whereas the self-assembly of 1 with preformed cluster [Co (OH )(piv) (Hpiv) ] in MeCN leads to the two-dimensional network of formula {[Co (piv) ] [Co ( Tp)(CN) ]  ⋅ 2CH CN} (3). These compounds were structurally characterized via single crystal X-ray analysis and their spectroscopic (FTIR, UV-Vis and Co NMR) properties and magnetic behaviours were also investigated.

Enlightening the Alkali Ion Role in the Photomagnetic Effect of FeCo Prussian Blue Analogues.

FeCo Prussian blue analogues of general formula ACo[Fe(CN)] are responsive, non-stoichiometric materials whose magnetic and optical properties can be reversibly switched by light irradiation. However, elucidating the critical influence of the inserted alkali ion, A, on the material's properties remains complicated due to their complex local structure. Here, by investigating soluble A ⊂ [Fe-Co] cyanido cubes (A = K, Rb, and Cs), both accurate structural and electronic information could be obtained.

Size-dependent compression of threaded alkyldiphosphate in head to head cyclodextrin [3]pseudorotaxanes.

The encapsulation of guests in a confined space enables unusual conformations and reactivities. In particular, the compression of akyl chains has been obtained by self-assembled molecular capsules but such an effect has not been reported in solution for pseudorotaxane architectures. By exploiting the tendency of cyclodextrin (CD) to form head to head [3]pseudorotaxanes and the hydrogen bonding abilities of phosphate groups, we have studied the effect of the CD dimer cavity on the conformation of threaded α,ω-alkyl-diphosphate axles.

Mapping C-H⋅⋅⋅M Interactions in Confined Spaces: (α-ICyD )Au, Ag, Cu Complexes Reveal "Contra-electrostatic H Bonds" Masquerading as Anagostic Interactions*.

What happens when a C-H bond is forced to interact with unpaired pairs of electrons at a positively charged metal? Such interactions can be considered as "contra-electrostatic" H-bonds, which combine the familiar orbital interaction pattern characteristic for the covalent contribution to the conventional H-bonding with an unusual contra-electrostatic component. While electrostatics is strongly stabilizing component in the conventional C-H⋅⋅⋅X bonds where X is an electronegative main group element, it is destabilizing in the C-H⋅⋅⋅M contacts when M is Au(I), Ag(I), or Cu(I) of NHC-M-Cl systems. Such remarkable C-H⋅⋅⋅M interaction became experimentally accessible within (α-ICyD )MCl, NHC-Metal complexes embedded into cyclodextrins.

The Atypical Hysteresis of [Fe(C F Tp) ]: Overlay of Spin-Crossovers and Symmetry-Breaking Phase Transition.

The [Fe (C F Tp) ] spin-crossover complex is an atypical molecular switch, which can be converted upon annealing between two archetypal spin-crossover behaviours: from an extremely gradual spin-crossover to a broad hysteretic spin-transition (of ca. 65 K). The hysteresis shows an uncommon "rounded shape" that is reproducible upon cycling temperature.

Solvothermal synthesis, structure and magnetic properties of heterometallic coordination polymers based on a phenolato-oxamato co-bidentate-tridentate ligand.

The use of solvothermal conditions has succesfully led to the preparation of heterometallic 1D coordination polymers from a co-bidentate-tridentate phenolato-oxamato ligand. The reaction of the N-(2-hydoxyphenyl)oxamic acid (ohpma) with acetate salts of transition metal ions at 80 °C has yielded the heterobimetallic [Cu(ohpma)M(OAc)(DMF)2] (M = Co (1); Mn (2)) and the heterotrimetallic [Cu(ohpma)Co0.57Mn0.

Insights into the antiproliferative mechanism of (C^N)-chelated half-sandwich iridium complexes.

Transition metal-based anticancer compounds, as an alternative to platinum derivatives, are raising scientific interest as they may present distinct although poorly understood mechanisms of action. We used a structure-activity relationship-based methodology to investigate the chemical and biological features of a series of ten (C^N)-chelated half-sandwich iridiumIII complexes of the general formula [IrCp*(phox)Cl], where (phox) is a 2-phenyloxazoline ligand forming a 5-membered metallacycle. This series of compounds undergoes a fast exchange of their chlorido ligand once solubilised in DMSO.

Correction: Thermo- and electro-switchable Cs⊂{Fe-Fe} cubic cage: spin-transition and electrochromism.

Correction for 'Thermo- and electro-switchable Cs⊂{Fe4-Fe4} cubic cage: spin-transition and electrochromism' by Jana Glatz et al., Chem. Commun.

Thermo- and electro-switchable Cs⊂{Fe-Fe} cubic cage: spin-transition and electrochromism.

A mixed valence Cs⊂{Fe4-Fe4} cyanido-cube was synthesized and structurally characterized. The molecule, which is robust in solution, shows remarkable electronic versatility. Electrochromic properties associated with nine different electronic states are observed in solution together with a thermo-induced spin-transition in the solid state.

Dual switchable molecular tweezers incorporating anisotropic Mn-salphen complexes.

An alternative strategy for the synthesis of terpyridine based switchable molecular tweezers has been developed to incorporate anisotropic Mn(iii)-salphen complexes. The free ligand was synthesized using a building block strategy based on Sonogashira coupling reactions and was then selectively metalated with manganese in a last step. The conformation of the tweezers was switched from an open 'W' shaped form to a closed 'U' form by Zn(ii) coordination to the terpyridine unit bringing the two Mn-salphen moieties in close spatial proximity as confirmed by X-ray crystallography.

Permethylated NHC-Capped α- and β-Cyclodextrins (ICyD ) Regioselective and Enantioselective Gold-Catalysis in Pure Water.

A series of water-soluble encapsulated copper(I), silver(I) or gold(I) complexes based on NHC-capped permethylated cyclodextrins (ICyD ) were developed and used as catalysts in pure water for hydration, lactonization, hydroarylation and cycloisomerization reactions. ICyD ligands gave cavity-based high regioselectivity in hydroarylations, and high enantioselectivities in gold-catalyzed cycloisomerizations reactions giving up to 98 % ee in water. These ICyD are therefore useful ligands for selective catalysis in pure water.

Electron Transfer in the Cs⊂{Mn Fe } Cubic Switch: A Soluble Molecular Model of the MnFe Prussian-Blue Analogues.

A mixed-valence {Mn Mn Fe Fe } cyanide-bridged molecular cube hosting a caesium cation, Cs⊂{Mn Fe }, was synthesized and structurally characterized by X-ray diffraction. Cyclic-voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable electrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin-state change near room temperature, which could be ascribed to a metal-to-metal electron transfer converting the {Fe -CN-Mn } pair into a {Fe -CN-Mn } pair.

Polymerization of rac-Lactide Using Achiral Iron Complexes: Access to Thermally Stable Stereocomplexes.

Enantiopure poly(lactic acid) (PLA) can form stereocomplexes when enantiomeric PLA chains are mixed in equivalent amounts. Such materials provide interesting features that might be suitable for numerous applications. Despite several advantages, the main drawback of PLA is its narrow window of processing, thus limiting its use for industrial applications.

Pyranopterin Related Dithiolene Molybdenum Complexes as Homogeneous Catalysts for CO Photoreduction.

Two original dithiolenes, with a pyrazine ring fused with a pyran ring carrying the dithiolene chelate, mimicking molybdopterin (MPT) present in the active site of formate dehydrogenases (FDHs), have been synthesized. The first one mimicks MPT in the dihydropyrazine form while the second mimicks MPT in the more biologically relevant tetrahydropyrazine form. Both have been structurally characterized as a ligand within a cobalt(cyclopentadienyl)(dithiolene) complex.

Thermally-Induced Spin Crossover and LIESST Effect in the Neutral [Fe(bik)(NCX)] Complexes: Variable-Temperature Structural, Magnetic, and Optical Studies (X = S, Se; bik = bis(1-methylimidazol-2-yl)ketone).

Two new iron(II) neutral complexes of bis(1-methylimidazol-2-yl)ketone (bik) with molecular formula [Fe(bik)(NCS)] () and [Fe(bik)(NCSe)] () have been synthesized and characterized by magnetic measurements, single-crystal X-ray diffraction, and solid state UV-vis spectroscopy. The temperature dependent magnetic susceptibility measurements of crystalline samples of both compound show the occurrence of a gradual spin transition centered at = 260 K and 326 K, respectively. The crystal structures of both compounds were determined at different temperatures, below and above the transition, in order to detect the structural changes associated with the spin transition.

A [Fe(Tp)(CN)] scorpionate-based complex as a building block for designing ion storage hosts (Tp: hydrotrispyrazolylborate).

Using a scorpionate-based complex, [FeIII(Tp)(CN)3]-, as a building block, a new cyanide-based molecular material [{FeIII(Tp)(CN)3}2NiII(H2O)2]·4H2O (1), which can be viewed as a lower dimensional model of Prussian blue analogues, was investigated as a lithium-ion storage host.

Six States Switching of Redox-Active Molecular Tweezers by Three Orthogonal Stimuli.

A six level molecular switch based on terpyridine(Ni-salphen) tweezers and addressable by three orthogonal stimuli (metal coordination, redox reaction, and guest binding) is reported. By a metal coordination stimulus, the tweezers can be mechanically switched from an open "W"-shaped conformation to a closed "U"-shaped form. Theses two states can each be reversibly oxidized by the redox stimulus and bind to a pyrazine guest resulting in four additional states.

Photochemical studies on bis-sulfide and -sulfone tethered polyenic derivatives.

This study focusses on the [2 + 2]-photocycloaddition of a symmetric polyenic system tethered by an aryl bis-sulfide or sulfone platform. Using direct irradiation or photosensitization, no expected ladderane product was isolated. In most cases, only tricyclic products including a single cyclobutane moiety were formed.

Synthesis, Characterization, and DFT Analysis of Bis-Terpyridyl-Based Molecular Cobalt Complexes.

Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions.