The Goldilocks principle in action: synthesis and structural characterization of a novel {Cu4(\u3bc3-OH)4} cubane stabilized by monodentate ligands

A {Cu4(\u3bc3-OH)4} compound, where four copper(II) and four \u3bc3-bridging oxygen atoms occupy alternate corners of a slightly distorted cube, has been prepared and structurally characterized. This species, formulated as [Cu4(\u3bc3-OH)4(Htmpz)8](ClO4)4\ub71.5Et2O (Htmpz = 3,4,5-1H-trimethyl pyrazole), can be classified as belonging to type I Cu4O4 cubane complexes, and is better described as two CuII\u2013(\u3bc-OH)2\u2013CuII units held together by four long Cu\u2013O bonds. The central distorted cubane core is stabilized by neutral monodentate ligands (Htmpz) and perchlorate anions, as demonstrated by single-crystal X-ray structure analysis. The title compound was obtained by hydrolysis of a dinuclear methoxo-bridged species, [Cu(\u3bc-OCH3)(Htmpz)2]2(ClO4)2, which was prepared by reaction of [Cu(Htmpz)4(ClO4)2] with methanol. All these reactions represent a nice example of the Goldilocks principle in action in coordination chemistry, since each single actor (solvent, counteranion, and ligand) has the \u201cjust right\u201d electronic, steric or coordinative properties which determine the fate of the final products

Luminescent blue emissive bis(alkynyl) borane compounds with a N,O-coordinated ligand

Five bis(alkynyl)boranes with a (imidazo[1,5-a]pyridin-3-yl)phenolate ligand have been synthesized and characterized both in solution (1H, 13C, 11B, 19F NMR) and in the solid state (X-ray). All derivatives, differing for the substituent R (H, Me, OMe, CF3, NMe2) in the para position of the phenylacetylene moieties, displayed blue fluorescence emission in solution, linearly correlated to the electronic properties of the substituent R (i.e., its σp Hammett constant). High Stokes shifts and good quantum yields were recorded. Time-Dependent Density Functional Theory (TD-DFT) calculations were performed to describe the percentage contribution of each fragment of the molecule to the frontier orbitals. Electron Density Difference Maps (EDDMs) calculated for all derivatives allowed to explain the emissive properties of the studied compounds

Spin dynamics in molecular ring nanomagnets: Significant effect of acoustic phonons and magnetic anisotropies

The nuclear spin-lattice relaxation rate 1/T_1_ is calculated for magnetic ring clusters by fully diagonalizing their microscopic spin Hamiltonians. Whether the nearest-neighbor exchange interaction J is ferromagnetic or antiferromagnetic, 1/T_1_ versus temperature T in ring nanomagnets may be peaked at around k_B_T=|J| provided the lifetime broadening of discrete energy levels is in proportion to T^3^. Experimental findings for ferromagnetic and antiferromagnetic Cu^II^ rings are reproduced with crucial contributions of magnetic anisotropies as well as acoustic phonons.Comment: 5 pages with 5 figures embedded, to be published in J. Phys. Soc. Jpn. 75, No. 10 (2006

Pemetrexed single agent chemotherapy in previously treated patients with locally advanced or metastatic non-small cell lung cancer

<p>Abstract</p> <p>Background</p> <p>The main objective of this study was to evaluate the safety of second-line pemetrexed in Stage IIIB or IV NSCLC.</p> <p>Methods</p> <p>Overall, 95 patients received pemetrexed 500 mg/m²i.v. over Day 1 of a 21-day cycle. Patients also received oral dexamethasone, oral folic acid and i.m. vitamin B12 supplementation to reduce toxicity. NCI CTC 2.0 was used to rate toxicity. All the adverse events were graded in terms of severity and relation to study treatment. Dose was reduced in case of toxicity and treatment was delayed for up to 42 days from Day 1 of any cycle to allow recovering from study drug-related toxicities. Tumor response was measured using the RECIST criteria.</p> <p>Results</p> <p>Patients received a median number of 4 cycles and 97.8% of the planned dose. Overall, 75 patients (78.9% of treated) reported at least one adverse event: 34 (35.8%) had grade 3 as worst grade and only 5 (5.2%) had grade 4. Drug-related events occurred in 57.9% of patients. Neutropenia (8.4%) and leukopenia (6.3 %) were the most common grade 3/4 hematological toxicities. Grade 3 anemia and thrombocytopenia were reported in 3.2% and 2.1% of patients, respectively. Diarrhea (6.3%), fatigue (3.2%) and dyspnea (3.2%) were the most common grade 3/4 non-hematological toxicities. The most common drug-related toxicities (any grade) were pyrexia (11.6%), vomiting, nausea, diarrhea and asthenia (9.5%) and fatigue (8.4%). Tumor Response Rate (CR/PR) in treated patients was 9.2%. The survival at 4.5 months (median follow-up) was 79% and the median PFS was 3.1 months. Twenty patients (21.1%) died mainly because of disease progression.</p> <p>Conclusion</p> <p>Patients with locally advanced or metastatic NSCLC could benefit from second-line pemetrexed, with a low incidence of hematological and non-hematological toxicities.</p