A zeolite family with chiral and achiral structures built from the same building layer.

Porosity and chirality are two of the most important properties for materials in the chemical and pharmaceutical industry. Inorganic microporous materials such as zeolites have been widely used in ion-exchange, selective sorption/separation and catalytic processes. The pore size and shape in zeolites play important roles for specific applications. Chiral inorganic microporous materials are particularly desirable with respect to their possible use in enantioselective sorption, separation and catalysis. At present, among the 179 zeolite framework types reported, only three exhibit chiral frameworks. Synthesizing enantiopure, porous tetrahedral framework structures represents a great challenge for chemists. Here, we report the silicogermanates SU-32 (polymorph A), SU-15 (polymorph B) (SU, Stockholm University) and a hypothetical polymorph C, all built by different stacking of a novel building layer. Whereas polymorphs B and C are achiral, each crystal of polymorph A exhibits only one hand and has an intrinsically chiral zeolite structure. SU-15 and SU-32 are thermally stable on calcination.

C,C-diacetylenic phosphaalkenes as heavy diethynylethene analogues.

A series of C,C-diacetylenic phosphaalkenes 1b-e has been prepared from 1-chloropenta-1,2-dien-4-ynes 6b-e in a reaction with Mes*PCl(2) (Mes* = 2,4,6-((t)Bu)(3)Ph) in the presence of LDA. Under identical conditions, isomeric butadiyne-substituted phosphaalkenes 2c-f can be obtained from 3-chloropenta-1,4-diynes 5c-f. The title compounds represent rare examples of diethynylethenes in which a constituting methylene has been replaced by a phosphorus center. The formation of both isomers can be rationalized by a common pathway that involves isomeric allenyllithium species. Spectroscopic, electrochemical, and theoretical investigations show that the phosphorus heteroatoms are an intrinsic part of the compounds' pi-systems and lead to decreased HOMO-LUMO gaps compared to those in all-carbon-based reference compounds.

Water as a hydrogen bonding bridge between a phenol and imidazole. A simple model for water binding in enzymes.

The X-ray crystal structure of the mono-hydrate of 2,2-bis(imidazol-1-ylmethyl)-4-methylphenol has been determined. Three hydrogen bonds hold water very tightly in the crystal, as determined by deuterium solid-state NMR. The hydrogen bond between the phenolic hydroxyl and water appears to have about the same strength as the direct hydrogen bond to imidazole, suggesting that the structure can be a good model for hydrogen bonds that are mediated by a water molecule in enzymes.

Self assembly, structure and properties of the decanuclear lanthanide ring complex, Dy10(OC2H4OCH3)30.

Self assembly produced high yields of the lanthanide ring complex Dy10(OC2H4OCH3)30, the largest lanthanide ring known, characterized by X-ray diffraction methods and by magnetic susceptibility as a function of temperature.

Validity of the classical monte carlo method to model the magnetic properties of a large transition-metal cluster: Mn19.

The susceptibility of the large transition-metal cluster [Mn19O12(MOE)14(MOEH)10].MOEH (MOE = OC2H2O-CH3) has been fitted through classical Monte Carlo simulation, and an estimation of the exchange coupling constants has been done. With these results, it has been possible to perform a full-matrix diagonalization of the cluster core, which was used to provide information on the nature of the low-lying levels.

Physical characterization of anhydrous and hydrous forms of the hydrochloride salt of BVT.5182 a novel 5-HT(6) receptor antagonist.

The physicochemical properties of 1-benzenesulfonyl-4-(piperazin-1-yl)-indole hydrochloride, a novel 5-HT(6) receptor antagonist for the treatment of obesity were characterized. Two solid state forms were identified at ambient conditions (23 degrees C): an anhydrate form (1) and a hydrate form (2), with 1.5 moles of H(2)O. The latter easily dehydrates and rehydrates without affecting the crystal morphology. Investigations of the propensity for interconversion between the two forms reveal that a) conversion of 2-->1 takes place above 145 degrees C and that b) conversion of 1-->2 only occurs after crystallization from supersaturated aqueous solutions at a water activity >or=0.94 or in the presence of comparable amounts of crystals of 2 in water at ambient conditions. However, in an equimolar suspension of 1 and 2 at 37 degrees C no phase transformation was observed. Thus, the difference in chemical potential between the two forms is small. Form 1 was shown to have overall favorable solid state properties and, hence, considered the preferred form for continued pharmaceutical development. The characterization was performed by means of light microscopy, scanning electron microscopy, powder X-ray diffraction, FTIR/NIR-spectroscopy, differential scanning calorimetry, hot stage microscopy, thermogravimetry, dynamic vapor sorption, Karl Fischer water content determination, phase stability studies of suspensions, solubility, and intrinsic dissolution rate measurements.

First example of low-valence ion substitution in Ln5O(OPri)13: mixed-valence europium oxoalkoxide [EuIII4EuIIO(OPri)12(HOPri)]HOPri.

The novel mixed-valence alkoxide [Eu3+(4)Eu2+O(OPri)12(HOPri)]HOPri (1) has been prepared and structurally and spectroscopically characterized. The three synthesis routes (i) metathesis of 4EuCl3, EuI2, and 14KOPri combined with hydrolysis with 1H2O, (ii) oxidation of 5[Eu4(OPri)10(HOPri)3]2HOPri with 1.5O2, and (iii) reduction of Eu5O(OPri)13 with 0.8[Eu4(OPri)10(HOPri)3]2HOPri all yielded pure 1, whereas (iv) reduction of Eu5O(OPri)13 with 0.36-0.5 mol of europium metal produced impure 1. The compound, having the average Eu oxidation number +2.8, is very sensitive toward further oxidation to Eu5O(OPri)13 and is part of a redox series of europium 2-propoxides with average oxidation states +2.5, +2.8, and +3. The square pyramidal molecular structure, containing an oxo-oxygen atom in the basal plane, is similar to that of the well-known Ln5O(OPri)13; the main difference is the substitution of an Eu3+(-)OPri pair for an Eu2+(-)HOPri pair in the basal plane. Fourier transform infrared (FT-IR) and UV-visible spectroscopy showed that the solid-state structure was retained on dissolution in hexane and toluene-HOPri. The compound was further characterized by differential scanning calorimetry and solubility studies.

A new strategy for the improvement of photophysical properties in ruthenium(II) polypyridyl complexes. Synthesis and photophysical and electrochemical characterization of six mononuclear ruthenium(II) bisterpyridine-type complexes.

The synthesis and characterization of six ruthenium(II) bistridentate polypyridyl complexes is described. These were designed on the basis of a new approach to increase the excited-state lifetime of ruthenium(II) bisterpyridine-type complexes. By the use of a bipyridylpyridyl methane ligand in place of terpyridine, the coordination environment of the metal ion becomes nearly octahedral and the rate of deactivation via ligand-field (i.e., metal-centered) states was reduced as shown by temperature-dependent emission lifetime studies. Still, the possibility to make quasi-linear donor-ruthenium-acceptor triads is maintained in the complexes. The most promising complex shows an excited-state lifetime of tau = 15 ns in alcohol solutions at room temperature, which should be compared to a lifetime of tau = 0.25 ns for [Ru(tpy)2]2+. The X-ray structure of the new complex indeed shows a more octahedral geometry than that of [Ru(tpy)2]2+. Most importantly, the high excited-state energy was retained, and thus, so was the potential high reactivity of the excited complex, which has not been the case with previously published strategies based on bistridentate complexes.

(C6H14N2)2[VO(HPO4)5B2O] x H2O x -H3PO4, a novel borophosphate cluster containing a single vanadium centre and linked by hydrogen bonds into a three-dimensional framework.

The title novel vanadium borophosphate compound, bis(1,4-diazonia[2.2.2]octane) mu(3)-oxo-oxopenta-mu-phosphato-diboronvanadium monohydrate phosphoric acid solvate, containing the cluster anion [VO(PO(3)OH)(5)B(2)O](4-), has been synthesized under mild hydrothermal conditions. Extensive O-H...O and N-H...O hydrogen bonding is observed between the molecular units.

Synthesis of an amino-functionalized model of the Fe-only hydrogenase active site.

A dinuclear 2Fe2S mimic 6 of the active site of the Fe-only hydrogenases has been synthesized. Complex 6 contains a free amino group which enables linkage to a protein backbone or to a redox active species for the study of electron transfer processes in proteins or in supramolecular systems. The structures of the complex 6 and its Boc-protected precursor 5 could be verified by X-ray crystallography.

Modification of binuclear Pt-Tl bonded complexes by attaching bipyridine ligands to the thallium site.

Complex formation of monomeric thallium(III) species with 2,2'-bipyridine (bipy) in dimethyl sulfoxide (dmso) and acetonitrile solutions was studied by means of multinuclear ((1)H, (13)C, and (205)Tl) NMR spectroscopy. For the first time, NMR signals of the individual species [Tl(bipy)(m)(solv)](3+) (m = 1-3) were observed despite intensive ligand and solvent exchange processes. The tris(bipy) complex was crystallized as [Tl(bipy)(3)(dmso)](ClO(4))(3)(dmso)(2) (1), and its crystal structure determined. In this compound, thallium is seven-coordinated; it is bonded to six nitrogen atoms of the three bipy molecules and to an oxygen atom of dmso. Metal-metal bonded binuclear complexes [(NC)(5)Pt-Tl(CN)(n)(solv)](n)(-) (n = 0-3) have been modified by attaching bipy molecules to the thallium atom. A reaction between [(NC)(5)Pt-Tl(dmso)(4)](s) and 2,2'-bipyridine in dimethyl sulfoxide solution results in the formation of a new complex, [(NC)(5)Pt-Tl(bipy)(solv)]. The presence of a direct Pt-Tl bond in the complex is convincingly confirmed by a very strong one-bond (195)Pt-(205)Tl spin-spin coupling ((1)J((195)Pt-(205)Tl) = 64.9 kHz) detected in both (195)Pt and (205)Tl NMR spectra. In solutions containing free cyanide, coordination of CN(-) to the thallium atom occurs, and the complex [(NC)(5)Pt-Tl(bipy)(CN)(solv)](-) ((1)J((195)Pt-(205)Tl) = 50.1 kHz) is formed as well. Two metal-metal bonded compounds containing bipy as a ligand were crystallized and their structures determined by X-ray diffractometry: [(NC)(5)Pt-Tl(bipy)(dmso)(3)] (2) and [(NC)(5)Pt-Tl(bipy)(2)] (3). The Pt-Tl bonding distances in the compounds, 2.6187(7) and 2.6117(5) A, respectively, are among the shortest reported separations between these two metals. The corresponding force constants in the molecules, 1.38 and 1.68 N/cm, respectively, were calculated using Raman stretching frequencies of the Pt-Tl vibrations and are characteristic for a single metal-metal bond. Electronic absorption spectra were recorded for the [(NC)(5)Pt-Tl(bipy)(m)(solv)] compounds, and the optical transition was attributed to the metal-metal bond assigned.

Model of the iron hydrogenase active site covalently linked to a ruthenium photosensitizer: synthesis and photophysical properties.

A model of the iron hydrogenase active site with the structure [(mu-ADT)Fe2(CO)6] (ADT = azadithiolate (S-CH2-NR-CH2-S), (2: R = 4-bromophenyl, 3: R = 4-iodophenyl)) has been assembled and covalently linked to a [Ru(terpy)2]2+ photosensitizer. This trinuclear complex 1 represents one synthetic step toward the realization of our concept of light-driven proton reduction. A rigid phenylacetylene tether has been incorporated as the linking unit in 1 in order to prolong the lifetime of the otherwise short-lived [Ru(terpy)2]2+ excited state. The success of this strategy is demonstrated by comparison of the photophysical properties of 1 and of two related ruthenium complexes bearing acetylenic terpyridine ligands, with those of [Ru(terpy)2]2+. IR and electrochemical studies reveal that the nitrogen heteroatom of the ADT bridge has a marked influence on the electronic properties of the [Fe2(CO)6] core. Using the Rehm-Weller equation, the driving force for an electron transfer from the photoexcited *[Ru(terpy)2]2+ to the diiron site in 1 was calculated to be uphill by 0.59 eV. During the construction of the trinuclear complex 1, n-propylamine has been identified as a decarbonylation agent on the [(mu-ADT)Fe2(CO)6] portion of the supermolecule. Following this procedure, the first azadithiolate-bridged dinuclear iron complex coordinated by a phosphine ligand [(mu-ADT)Fe2(CO)5PPh3] (4, R = 4-bromophenyl) was synthesized.

Synthesis, redox properties, and EPR spectroscopy of manganese(III) complexes of the ligand N,N-bis(2-hydroxybenzyl)-N'-2-hydroxybenzylidene-1,2-diaminoethane: formation of mononuclear, dinuclear, and even higher nuclearity complexes.

The synthesis and characterization of the title trisphenolate ligand are described. From its reaction with manganese(III) three complexes were isolated. The crystal structures revealed one pentacoordinate monomer and two similar dimers with different solvents of crystallization. In the dimers the metal ions are hexacoordinate and connected through bridging of two phenolates. A combination of electrochemistry and EPR spectroscopy showed that, in acetonitrile, the isolated batches were all identical and mainly monomeric, indicating that the mononuclear complex is in equilibrium with the dimer and perhaps also with complexes of higher nuclearity, as suggested by the detection of both the trimer and the tetramer by electrospray ionization mass spectrometry (ESI-MS). The successful use of the monomer batch as an epoxidation catalyst indicated that a high-valent manganese-oxo species can be formed, although it is probably short-lived. This is also suggested by EPR studies of the species formed by electrochemical oxidation of the complex. Upon one-electron oxidation, a manganese(IV) species was formed, which was at least partly converted to another species containing a phenoxy radical.