Anion-encapsulating, discrete prism and extended frusta, from trimetallated triangular macrocycles and linkers.

Reaction of a trinuclear triangular macrocyclic complex PbL(CFSO) with bidentate linkers in a ratio of 3 equiv. of linker per 2 equiv. of complex, produces a prismatic structure with 4,4'-dipyridyl, and two unprecedented, extended 3D frustum-like structures with 1,2-di(4-pyridyl)ethylene and 1,4-di(4-pyridyl)benzene.

Modulation of the structural information in shape-defined heterocyclic strands: the case of a (pyridine-hydrazone)pyrazine ligand.

Metal ions (Ag, Cd, Eu, Sm) and protons can, through coordination and protonation, modulate in three specific ways the structural information contained in the pyrazine-based heterocyclic strand L (obtained from 2,5-bis(methylhydrazino)pyrazine and 2 equivalents of 2-pyridinecarboxaldehyde), thus generating two linear rod-like conformations and a bent one. This conformational diversity is associated with a structural one that consists of two diprotonated forms (HL(PF) and HL(CFSO)), a polymeric architecture [AgL](CFSO), two rack-like complexes ([EuHL(CFSO)](PF) and [SmHL(CFSO)](PF)) and a grid-like structure ([CdL](CFSO)).

Supramolecular reactions of metallo-architectures: Ag-double-helicate/Zn-grid, Pb-grid/Zn-grid interconversions, and Ag-double-helicate fusion.

Supramolecular reactions are of importance in many fields. We report herein three examples where complexes of hydrazone-based ligands are involved. A Ag-double-helicate was converted, by treatment with Zn(OTf), into a Zn-grid (exchange of metal ions and change of the nature of the initial complex).

Controlled Folding, Motional, and Constitutional Dynamic Processes of Polyheterocyclic Molecular Strands.

General design principles have been developed for the control of the structural features of polyheterocyclic strands and their effector-modulated shape changes. Induced defined molecular motions permit designed enforcement of helical as well as linear molecular shapes. The ability of such molecular strands to bind metal cations allows the generation of coiling/uncoiling processes between helically folded and extended linear states.

A Ca(2+)-, Mg(2+)-, and Zn(2+)-Based Dendritic Contractile Nanodevice with Two pH-Dependent Motional Functions.

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.

Coupled nanomechanical motions: metal-ion-effected, pH-modulated, simultaneous extension/contraction motions of double-domain helical/linear molecular strands.

A new class of shape-enforced synthetic polyheterocyclic molecular strands, containing both a helical and a linear domain, has been designed and synthesized. On reaction with Pb(II), under the effect of cation binding to the coordination subunits, the helical section unfolds into a linear shape in the complex and the linear domain folds into a helical ligand wrapped around the bound cations. Such double-domain ligand strands are thus able to undergo a combined unfolding-folding interconversion on binding and release of metal cations.

Grid-double-helicate interconversion.

An interconversion between a binuclear Cu(I) double helicate and a tetranuclear Cu(II) grid is reported. The passage from the Cu(I) double helicate to the Cu(II) grid occurs through oxidation of Cu(I) into Cu(II) or through displacement of Cu(I) by Cu(II). The conversion of the Cu(II) grid into the Cu(I) double helicate occurs through treatment of the grid with triflic acid, reduction of Cu(II) with ascorbic acid, and neutralization with triethylamine.

Synthetic molecular machines and polymer/monomer size switches that operate through dynamic and non-dynamic covalent changes.

The present chapter is focused on how synthetic molecular machines (e.g. shuttles, switches and molecular motors) and size switches (conversions between polymers and their units, i.

Modulation of self-assembly and magnetism of Cu(II) grids in solution.

Depending on the Cu(II)/ligand molar ratio, a pyrimidine-based ligand generates a tetranuclear grid (1/1) or a dinuclear stick (2/1). EPR, MS and visible spectroscopy studies suggest that dilution produces partial dissociation of the grid in solution. Replacement of 2-H-pyrimidine by a 2-phenyl-triazine unit prevents the dissociation of the grid.

Places and chemistry: Strasbourg--a chemical crucible seen through historical personalities.

At the crossroads of Europe, having the particularity to be influenced and shaped during their history by both French and German cultures and systems, Strasbourg and Alsace have produced internationally significant science. This review is focused on the personalities of Strasbourg and Alsace who influenced many aspects of both the development and the perception of chemistry in particular.

Ru(II) multinuclear metallosupramolecular rack-type architectures of polytopic hydrazone-based ligands: synthesis, structural features, absorption spectra, redox behavior, and near-infrared luminescence.

A novel class of polytopic hydrazone-based ligands was synthesized. They gave heteroleptic Ru(II) polynuclear rack-like complexes of formula [Ru(n)terpy(n)(bridging molecular strand)](2n+) (terpy=2,2':6',2''-terpyridine). The new rack-like systems can be viewed as being made of two identical or roughly identical peripheral subunits separated by several similar metal-containing spacer subunits.

Control of relative direction and amplitude in extension/contraction motions of molecular strands induced by ion binding.

The shape of ligand strands composed of six-membered aza-heterocycles (het) connected at the alpha and alpha' positions by hydrazone (hyz) units is determined in a predictable fashion by the nature of the heterocyclic groups (pyridine, pyrimidine, pyrazine etc.), and covers the range from extended linear to compact helical structures. The binding of metal ions to the coordination subunits, defined by the het-hyz sequences, leads to marked shape changes by inter-converting bent and linear conformations of the subunits, thus inducing relative motions of strand domains either in the same (con-sense, "twirling") or in opposite (dis-sense, "flapping") directions.

Copper(II) dinuclear pyrazine-based rack-type complexes: preparation, structure, and magnetic properties.

A novel class of ditopic ligands, 1, was synthesized by the reaction of 2,5-pyrazine-dicarboxaldehyde with 2 equiv of acyl-/aroyl-hydrazine. Their structures were confirmed by 1D and 2D NMR and by X-ray crystallography. They gave heteroleptic Cu(II) dinuclear rack-like complexes of the formula [Cu(2)1(terpy)(2)](OTf)(4), thus undergoing shape changes of significant amplitude.

Solvent-modulated reversible conversion of a [2 x 2]-grid into a pincer-like complex.

The triazine derived ligand reacts with one equivalent of Co(II) salts to give complexes whose architecture depends on the solvent employed: the [2 x 2]-grid like tetranuclear complex and the pincer-like mononuclear complex, obtained respectively by crystallization from nitromethane and from acetonitrile may be interconverted reversibly, the grid-pincer conversion being markedly accelerated by adding an amine.

Solid-state self-assembly of polymeric double helicates leading to linear arrays of silver(I) ions and reversible strand/double helix interconversion in solution.

Reaction of a bent py-hyz-pym-hyz-pym 1 and of a linear py-hyz-py-hyz-pym 3 (py=pyridine; pym=pyrimidine; hyz=hydrazone) ligand strands with silver(I) tetrafluoroborate in CH(3)NO(2) generates double-helical dinuclear 2 and trinuclear 4 complexes. These complexes form polymeric, highly ordered solid-state structures, with wirelike, linear continuous or discontinuous polycationic Ag(n) (+) arrays with Ag--Ag distances of 2.78 to 4.

Formation of RACK- and grid-type metallosupramolecular architectures and generation of molecular motion by reversible uncoiling of helical ligand strands.

The interaction of appropriate metal ions (Pb(II), Zn(II)) with helical ligand strands, obtained by hydrazone polycondensation, generates polymetallic supramolecular architectures of rack and grid types, by uncoiling of the ligand. The interconversion between the helical free ligand and the linearly extended ligand in the complexes produces reversible ion-induced, nanomechanical molecular motions of large amplitude. It has been integrated in an acid-base neutralisation fuelled process, which links the extension/contraction of the ligand strands to alternating changes in pH.

Synthesis, structural features, absorption spectra, redox behaviour and luminescence properties of ruthenium(ii) rack-type dinuclear complexes with ditopic, hydrazone-based ligands.

The isomeric bis(tridentate) hydrazone ligand strands 1 a-c react with [Ru(terpy)Cl3] (terpy=2,2':6',2''-terpyridine) to give dinuclear rack-type compounds 2 a-c, which were characterised by several techniques, including X-ray crystallography and NMR methods. The absorption spectra, redox behaviour and luminescence properties (both in fluid solution at room temperature and in rigid matrix at 77 K) of the ligand strands 1 a-c and of the metal complexes 2 a-c have been studied. Compounds 1 a-c exhibit absorption spectra dominated by intense pi-pi* bands, which, in the case of 1 b and 1 c, extend within the visible region, while the absorption spectra of the rack-type complexes 2 a-c show intense bands both the in the UV region, due to spin-allowed ligand-centred (LC) transitions, and in the visible, due to spin-allowed metal-to-ligand charge-transfer (MLCT) transitions.

Reversible folding/unfolding of linear molecular strands into helical channel-like complexes upon proton-modulated binding and release of metal ions.

The binding of appropriate metal ions to linear ligand strands obtained by hydrazone polycondensations generates channel-like complexes by reversible coiling of the ligand, thus allowing the generation of ion-induced, acid-base neutralisation fueled, molecular nanomechanical contraction/extension motions of large amplitude.

Contraction/extension molecular motion by protonation/deprotonation induced structural switching of pyridine derived oligoamides.

NMR, mass spectrometry and X-ray diffraction studies show reversible structural interconversion between helical and extended forms of pyridine derived oligoamide molecular strands, by simple protonation/deprotonation.