Palladium(II) halide complexes with 2,5-dimethyl-, 2-amino-, 2-amino-5-methyl-, 2-ethylamino- and 2-mercapto-5-methyl-1,3,4-thiadiazole

Some palladium(II) halide complexes with 2,5-dimethyl- (DTZ), 2-amino- (ATZ), 2-amino-5-methyl- (MATZ), 2-ethylamino- (EATZ) and 2-mercapto-5-methyl-1,3,4-thiadiazole (MTTZ) have been prepared and studied: PdX₂ · 2L (L = DTZ, ATZ, MATZ : X = Cl, Br, I; L = EATZ: X = Br, I; L = MTTZ: X = I), PdCl₂ · 2.5EATZ, PdCl₂ · 3MTTZ, PdBr₂ · 1.5MTTZ and PdX₂ · L (L = DTZ, ATZ, MATZ, EATZ: X = Cl, Br; L = MTTZ: X = Cl(H₂O), Br). In the PdX₂ · 2L, PdCl₂ · 2.5EATZ and PdCl₂ · 3MTTZ complexes the palladium ions are cis-(2X, 2L)-coordinated, the coordination sites being N_ring for DTZ, NR₂ for ATZ, MATZ, EATZ and C = S for MTTZ. PdBr₂ · 1.5MTTZ may be formulated as cis[PdBr₂-2L] · [PdBr₂ · L]. In the PdX₂ · L complexes the ligand very likely acts as bidentate by using a ring-nitrogen atom as the second coordination site.     

13C-NMR. Analysis of Dihydrogranaticin Methyl Ester. A case of mixed biogenesis

The ¹³C-NMR. spectrum of dihydrogranaticin methyl ester has been completely analyzed. Feeding experiments of CH₃ ¹³COONa to a culture of Streptomyces olivaceus have shown that only a sixteen carbon moiety of the antibiotic granaticin is of polyketide origin, thus confirming the hypothesis of a mixed biogenesis for this natural substance.     

1.6-W self-referenced frequency comb at 2.06 μm using a Ho:YLF multipass amplifier

A high-power optical frequency comb at 2.06 μm has been generated using a Ho:YLF multipass amplifier seeded by the long wavelength supercontinuum tail of an octave-spanning Er:fiber comb source. The Ho:YLF amplifier showed a net gain larger than 30 dB from 2048 to 2068 nm, allowing the generation of a 20 nm bandwidth comb with a mode spacing of 100 MHz and a power per mode ranging from 20 to 370 μW. In the time domain, the amplified comb corresponds to a pulse train with 1.6 W total power and 508 fs transform-limited pulse duration. Using a self-referencing f-2f interferometer and a phase-locking loop, spectral narrowing of the offset frequency down to less than 17 Hz has been achieved.     

Demonstration of differential phase-shift keying demodulation at 10 Gbit/s optimal fiber Bragg grating filters

Optimal demodulation of differential phase-shift keying signals at 10 Gbit/s is experimentally demonstrated using a specially designed structured fiber Bragg grating composed by Fabry-Perot coupled cavities. Bit-error-rate measurements show that, as compared with a conventional Gaussian-shaped filter, our demodulator gives approximately 2.8 dB performance improvement.     

Electronic correlations decimate the ferroelectric polarization of multiferroic homn2o5

We show that electronic correlations decimate the intrinsic ferroelectric polarization of multiferroic manganites RMn2O5, where R is a rare earth element. Such is manifest from ab initio band structure computations that account for the Coulomb interactions between the manganese 3d electrons--the root of magnetism in RMn2O5. Including these leads to an amplitude and direction of polarization of HoMn2O5 that agree with experiment. The decimation is caused by a near cancellation of the ionic polarization induced by the lattice and the electronic one due to valence charge redistributions.     

Total scattering investigation of materials for clean energy applications: the importance of the local structure

In this Perspective article we give an account of the application of total scattering methods and pair distribution function (PDF) analysis to the investigation of materials for clean energy applications such as materials for solid oxide fuel cells and lithium batteries, in order to show the power of this technique in providing new insights into the structure-property correlation in this class of materials.     

Solution structure of some lambda(3) Iodanes: an (17)O NMR and DFT study

The structure of a series of I-O bonded bis(acyloxy)iodoarenes and benzoiodoxolones in chloroform solution has been investigated by 17O NMR spectroscopy and by density functional theory (DFT) calculations, employing the PBE0 functional together with the LANL2DZ basis set extended with polarization (d) and diffuse (p) functions. This combined approach allowed us to ascertain that, although these classes of lambda(3) iodanes maintain in chloroform solution their solid state "T-shaped" structure, a degenerate [1,3] sigmatropic shift of iodine between the two oxygens of the acyloxy groups occurs in solution. The energy barrier involved in this process differs in the two classes, thus causing significant differences in the 17O NMR spectra, at room temperature, of the two classes of compounds.     

Electrophosphorescent homo- and heteroleptic copper(I) complexes prepared from various bis-phosphine ligands

Homo- and heteroleptic copper(I) complexes obtained from various chelating bis-phosphine ligands and Cu(CH3CN)4BF4 have been used for the preparation of light emitting devices.     

Tm-doped LiLuF4 crystal for efficient laser action in the wavelength range from 1.82 to 2.06 microm

Room-temperature continuous-wave laser action in a novel Tm-doped LiLuF(4) crystal emitting at around 1.9 microm is demonstrated. The crystal growth process, spectroscopic measurements, and laser performance are presented for different Tm concentrations. An overall tunability extending from 1817 to 2056 nm, a slope efficiency of 46%, and a maximum output power in excess of 1.1 W are reported.     

Hydroxy-3-Phenylcoumarins as Multitarget Compounds for Skin Aging Diseases: Synthesis,Molecular Docking and Tyrosinase,Elastase, Collagenase and Hyaluronidase Inhibition,and Sun Protection Factor

Skin aging is a progressive biological process of the human body, and it is not only time-dependent. Differently substituted 3-phenylcoumarins proved to efficiently inhibit tyrosinase. In the current work, new substitution patterns have been explored, and the biological studies were extended to other important enzymes involved in the processes of skin aging, as elastase, collagenase and hyaluronidase. From the studied series, five compounds presented inhibitory activity against tyrosinase, one compound against elastase, eight compounds against collagenase and two compounds against hyaluronidase, being five compounds dual inhibitors. The 3-(4′-Bromophenyl)-5,7-dihydroxycoumarin (1) and 3-(3′-bromophenyl)-5,7-dihydroxycoumarin (2) presented the best profiles against tyrosinase (IC₅₀ = 1.05 µM and 7.03 µM) and collagenase (IC₅₀ = 123.4 µM and 110.4 µM); the 3-(4′-bromophenyl)-6,7-dihydroxycoumarin (4) presented a good inhibition against tyrosinase and hyaluronidase; the 3-(3′-bromophenyl)-6,7-dihydroxycoumarin (5) showed an effective tyrosinase and elastase inhibition; and 6,7-dihydroxy-3-(3′-hydroxyphenyl)coumarin (11) presented a dual profile inhibition against collagenase and hyaluronidase. Furthermore, considering the overall activities tested, compounds 1 and 2 proved to be the most promising anti-aging compounds. These compounds also showed to have a photo-protective effect, without being cytotoxic to human skin keratinocyte cells. To predict the binding site with the target enzymes, computational studies were also carried out.