Methyltrioxorhenium(VII) (MTO) forms octahedral adducts with bidentate Lewis bases. These complexes were isolated and fully characterized, including X-ray crystallography. The compounds display distorted octahedral geometry in the solid state with a tendency of disorder concerning the Re central atom. At elevated temperatures, they undergo rapid ligand-exchange reactions in solution. The ease of this ligand exchange depends mainly on the Lewis basicity of the ligand. The more Lewis basic the ligand is, the stronger the metal-ligand interaction is, as can be shown by NMR spectroscopy. All examined complexes are temperature stable but quite sensitive to light and moisture. In the presence of H(2)O(2), the complexes form very active and highly selective epoxidation catalysts. Peroxo complexes are generated, and at least one of the Re-N interactions is cleaved during this process. Total ligand dissociation only occurs in the case of very weakly coordinating bidentate ligands. The peroxo complexes of the MTO Lewis base adducts are, in general, more sensitive to water than MTO itself.

Rhenium(I) N-heterocyclic carbene complexes of the type [HNCH 2 CH 2 NHCRe(L-L)(CO) 3 ] + have been prepared, where L-L ) 4,4′-dimethoxy-2,2′-bipyridine (2), 4,4′-bis(tert-butyl)-2,2′-bipyridine (3), 2,2′-bipyridine (4), 4,4′-dichloro-2,2′-bipyridine (5), 4,4′-bis(carbomethoxy)-2,2′-bipyridine (6), 5-phenyl-1,10-phenanthroline (7), and o-phenylenebis(diphenylphosphine) (8). The molecular structures of 4, 6, and 8 have been determined by X-ray analyses and show Re-C(carbene) bond distances of 2.171(7), 2.163(4), and 2.199(6) Å, respectively. HF-SCF and MP 2 calculations on the model compound [HNCH 2 CH 2 NHCRe(NHCHCHNH)-(CO) 3 ] + (4m) show that the HOMO is nonbonding d(Re) and the LUMO is mainly π*(diimine) with partial p z (carbene) character. CIS calculations on the excited state of optimized 4m suggest that the lowest energy absorption originates from a HOMO to LUMO spin-forbidden transition. Complexes 2-7 are emissive at room temperature and 77 K. The roomtemperature and 77 K luminescence data of 2-6 are consistent with emission from a 3 -MLCT state. The nature of the emission of 7 at room temperature is also 3 MLCT but changes to IL at 77 K. Complex 8 does not emit at room temperature, but at 77 K, the IL π(pdpp) f π*(pdpp) emission is observed. The combination of detailed spectroscopic studies and theoretical calculations reveal that the emitting state at room temperature is 3 [d(Re) f π*-(diimine)], with the latter exhibiting partial σ*(carbene) parentage. The excited-state energies and redox potentials can be tuned using diimine ligands with varying electrondonating/accepting abilities.

BackgroundCiliary neurotrophic factor (CNTF), a member of the interleukin-6 cytokine family, has been implicated in the development, differentiation and survival of retinal neurons. The mechanisms of CNTF action as well as its cellular targets in the retina are poorly understood. It has been postulated that some of the biological effects of CNTF are mediated through its action via retinal glial cells; however, molecular changes in retinal glia induced by CNTF have not been elucidated. We have, therefore, examined gene expression dynamics of purified Müller (glial) cells exposed to CNTF in vivo.Methodology/Principal FindingsMüller cells were flow-sorted from mgfap-egfp transgenic mice one or three days after intravitreal injection of CNTF. Microarray analysis using RNA from purified Müller cells showed differential expression of almost 1,000 transcripts with two- to seventeen-fold change in response to CNTF. A comparison of transcriptional profiles from Müller cells at one or three days after CNTF treatment showed an increase in the number of transcribed genes as well as a change in the expression pattern. Ingenuity Pathway Analysis showed that the differentially regulated genes belong to distinct functional types such as cytokines, growth factors, G-protein coupled receptors, transporters and ion channels. Interestingly, many genes induced by CNTF were also highly expressed in reactive Müller cells from mice with inherited or experimentally induced retinal degeneration. Further analysis of gene profiles revealed 20–30% overlap in the transcription pattern among Müller cells, astrocytes and the RPE.Conclusions/SignificanceOur studies provide novel molecular insights into biological functions of Müller glial cells in mediating cytokine response. We suggest that CNTF remodels the gene expression profile of Müller cells leading to induction of networks associated with transcription, cell cycle regulation and inflammatory response. CNTF also appears to function as an inducer of gliosis in the retina.

have been synthesized by the reaction of bimetallic tetraacetates with FPA in a 1:2 stoichiometry. They have been investigated as models of oligomeric and polymeric complexes of analogous composition. UV/Vis absorption spectroscopy and cyclic voltammetry indicate that Rh 2 (O 2 CCF 3 ) 4 possesses the strongest inductive effect of the three bimetallic tetracarboxylates examined in this study. Complex 1 was additionally characterized by single crystal X-ray analysis, revealing a Mo−Mo distance of 214.22(3) pm, which is elongated in comparison to Mo 2 (O 2 CCF 3 ) 4 [209.0(4) [a]

Isolated quadruply bonded dimolybdenum(II,II) complexes have been grafted onto the surface of hexagonal MCM-41 mesoporous silica by diffusion of an excess of the complex salts [Mo 2 (MeCN) ] 2 into calcined and dehydrated MCM-41 in dry acetonitrile at room temperature. The physical properties of the resulting unstable materials, together with the nature of the host±guest interactions and the structure of supported molybdenum species, have been characterised by means of elemental analysis, powder X-ray diffraction, N 2 adsorption, FTIR and MAS NMR ( 13 C, 29 Si, 31 P) spectroscopy.

Complexes of the composition W(O)(2)(Cl)(2)L(2) and W(O)(2)(R)(2)L(2) (R = Me, Et; L(2) = bidentate Lewis base ligand) have been prepared and are fully characterized (including an exemplary X-ray crystal structure of W(O)(2)(Cl)(2)(4,4'-di-tert-butyl-2,2'-bipyridine)). This latter compound crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 8.3198(1) A, b = 13.3224(2) A, c = 18.0415(2) A, and Z = 4. The title complexes are applied as catalysts in olefin epoxidation catalysis with tert-butyl hydroperoxide (TBHP) as the oxidizing agent. The W(VI) complexes display only moderate turnover frequencies but can be reused several times without loss of catalytic activity. The highest activity can be achieved at reaction temperatures of ca. 90 degrees C. Chloro derivatives are somewhat more active than alkyl complexes, and sterically less crowded complexes show also higher activities than their congeners with bulky ligands L(2). Kinetic examinations show that the catalyst formation is the rate determining step and it is observed that tert-butyl alcohol, the byproduct of the epoxidation reaction, acts as a competitor for TBHP, thus lowering the reaction velocity during the course of the reaction but not irreversibly destroying the catalyst.

The tetranuclear compounds M 2 (O 2 C-R) 4 L 2 [M = Rh, R = nC 7 H 15 , L = ferrocenyl-4-pyridylacetylene (FPA) (1a); M = Rh, R = CH 3 , L = FPA (1b); M = Mo, R = CF 3 , L = FPA (2b); M = Rh, R = nC 7 H 15 , L = 4-ferrocenylpyridine (FP) (3a); M = Rh, R = CH 3 , L = FP (3b); M = Mo, R = nC 7 H 15 , L = FP (4a); M = Mo, R = CF 3 , L = FP (4b)] have been synthesized by the reaction of bimetallic tetracarboxylates with L in a 1:2 ratio, in a noncoordinating solvent. The reaction of Mo 2 (O 2 CnC 7 H 15 ) 4 with FPA in a 1:2 molar ratio leads to a trinuclear compound Mo 2 (O 2 C-nC 7 H 15 ) 4 (FPA) (2a). A soluble oligomer [Rh 2 (O 2 C-nC 7 H 15 ) 4 (BPEF)] n [5, BPEF = 1,1Ј-bis(4-pyridylethynyl)ferrocene] is obtained by the reaction of Rh 2 (O 2 CnC 7 H 15 ) 4 with BPEF in a 1:1 ratio in CH 2 Cl 2 or CHCl 3 ,

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