Synthesis and Characterization of a Trisheteroleptic RuII‐Based Molecular Switch

The synthesis of a trisheteroleptic ruthenium complex [Ru(tb)(dppz)(tmbiH₂)][PF₆]₂ (tb=4,4′‐di‐tert‐butyl‐2,2′‐bipyridine, dppz=dipyrido[3,2‐a:2′,3′‐c]phenazin, tmbiH₂=5,6,5′,6′‐tetramethyl‐2,2′‐bibenzimidazole) is described. In addition, the structural characterisation by means of 1D, 2D ¹H NMR spectroscopy, and mass spectrometry, along with determination of the solid‐state structure of the important precursor Ru(tb)(dppz)Cl₂, supports the proposed octahedral coordination geometry. The capability of tmbiH₂ to form hydrogen bonds is corroborated by the solid‐state structure. The photochemical characteristics of this complex can be described as a combination of the “light switch” effects, which are either attributed to the dppz or to the tmbiH₂ ligand. To illustrate the molecule’s double switchable features, steady‐state absorption and emission measurements were performed, which include the determination of the quantum yield and the pK_a values of the acidic protons of the tmbiH₂ ligand. Notably, the emission lifetimes are sensitive to the solvents used. This phenomenon is due to a proton‐coupled deactivation of the excited metal‐to‐ligand charge transfer (MLCT) state of the complex.     

Cyclometalated platinum(II) complexes containing monodentate phosphines: antiproliferative study

Reaction of cyclometalated platinum(II) precursor [Pt(C^N)Cl(dmso)], 1, C^N = N(1), C(2′)-chelated deprotonated 2-phenylpyridine and dmso = dimethylsulfoxide, with 1 equivalent of triphenyl phosphine, PPh₃, or 1,3,5-triaza-7-phosphaadamantane, PTA, gave the complex [Pt(C^N)Cl(PPh₃)], 2, or [Pt(C^N)Cl(PTA)], 3, respectively. On the basis of careful multinuclear NMR spectroscopy, supported by a number of 2D NMR experiments, structures of the complexes 2 and 3 in solution were determined to be neutral four coordinate. The X-ray crystallography indicated that the solid-state structure of complex 3 comprised a common square-planar geometry around platinum(II). Cytotoxicity of the complexes 2 and 3 was studied in three human cancer cell lines derived from ovarian carcinoma (CH1), lung carcinoma (A549), and colon carcinoma (SW480).     

Double diffractive higgs and di-photon production at the Tevatron and LHC

We use the Monte Carlo generator to predict the cross-sections for double diffractive higgs and di-photon production at the Tevatron and LHC. We find that the higgs production cross-section is too small to be observable at Tevatron energies, and even at the LHC observation would be difficult. Double diffractive di-photon production, however, should be observable within one year of Tevatron Run II.     

Messungen der Winkelverteilung der 440 keV-γ-Strahlung aus der Reaktion23Na (p,p′ γ)23Na in den ResonanzenE p =1281 keV undE p =1456 keV

The angular distribution of the 440 keV-γ-radiation following the reaction²³Na(p, p′)²³Na has been measured. The experimental results areW(Θ)=1-(0,147±0,05)P ₂(cosΘ) in the resonanceE _p =1281 keV andW(Θ)=1-(0,099 ± 0,06)P ₂(cosΘ) in the resonanceE _p =1456 keV.     

Charge-separation in uranium diazomethane complexes leading to C-H activation and chemical transformation

The reaction of diphenyldiazomethane with [((t-BuArO)3tacn)UIII] (1) results in an eta(2)-bound diphenyldiazomethane uranium complex. This complex exhibits unusual electronic properties as a charge-separated species with a radical anionic open-shell ligand, [((t-BuArO)3tacn)UIV(eta2-NNCPh2)] (2). Treating Ph2CN2 with a uranium complex that contains a sterically more demanding adamantane functionalized ligand, [((AdArO)3tacn)UIII] (3) results in an unprecedented C-H activation and nitrogen insertion to produce a five-membered heterocyclic indazole complex, [((AdArO)3tacn)UIV(eta(2)-3-phen(Ind))] (5). X-ray crystallography and spectroscopic characterization of these two compounds show that the [((t-BuArO)3tacn)UIV(eta(2)-NNCPh2)] compound is a U(IV) complex with a radical anionic ligand, whereas [((AdArO)3tacn)UIV(eta(2)-3-phen(Ind))] is a U(IV) f (2) species with a closed-shell ligand.