Nitro-Porphyrin Entrapped in a Silica Matrix by Sol-Gel Methodology

This work describes the preparation of the iron (III) porphyrin, FeTDCNO₂, entrapped in a silica matrix in the form of powder (FePD) or thin film using the sol-gel process. The films were obtained from sols using the dip-coating technique. The variables involved in the FePD preparation were analysed by a fractional factorial design with resolution 5, designated by 2 _V ^{5 – 1}. The variables which present a positive effect and maximise the loading of the studied ironporphyrin on the FePD material are solvent, water volume and reaction time. The utilization of pyridine or imidazole as template does not affect the preparation of the FePD material. The UV-visible absorption spectra of all prepared materials present the characteristic Soret band of ironporphyrins at 419–420 nm.The materials were analysed by thermogravimetric analysis, isotherm of nitrogen adsorption, ²⁹Si NMR and scanning electron micrograph. The catalytic performance of FePD-imidazole on the epoxidation of z-cyclooctene with iodosylbenzene is similar to that of FeTDCNO₂ in homogeneous solution (60 and 52%).     

Thermo-kinetic behaviour of Ge20Te75I5 glass for infrared optics

The iodine-doped GeTe₄ infrared chalcogenide glass was studied by means of differential scanning calorimetry DSC, X-ray diffraction XRD, Raman spectroscopy and infrared microscopy. Extensive non-isothermal thermo-kinetic characterisation of the glass transition, crystallisation and melting phenomena was performed in dependence on the particle size. The Tool–Narayanaswamy–Moynihan model was applied to describe the enthalpy relaxation processes: the compositional evolution of the relaxation parameters was then explained in terms of the structural changes and movements of the characteristic structural units. Mathematic deconvolution was applied to treat the complex crystallization kinetics – two crystal growth sub-processes were identified and described in terms of the autocatalytic ?esták-Berggren model. Based on the XRD and microscopic analyses the following crystallization mechanisms were revealed: initial precipitation of tellurium (surface-located) followed by a combined surface- and bulk-located formation of GeTe and GeI₄ phases. Based on the DSC results obtained for fine powders, the presence of mechanically induced defects was found to accelerate the Te precipitation, the consequences of which are discussed with regard to the performance of nowadays glass stability criteria.     

2,3,6,7,8,9-hexahydro-8,8-dimethyl-5-phenyl-1-H1,4-benzodiazepin-6-one

Several approaches for the synthesis of the title compound 1 were investigated. Treatment of the ethane-1,2-diamine derivative 2 with phosphoryl chloride afforded 3-chloro-5,5-dimethylcyclohex-2-enone (3) and 1-(5,5-dimethyl-3-oxocyclohex-1-enyl)-4,5-dihydro-2-phenylimidazole (4) , The reaction of 2-benzoyl-dimedone (5) with an equimolar amount of ethane-1,2-diamine led to the 2:1 adduct 6 , whereas with an excess of ethane-1,2-diamine, 4,5-dihydro-2-phenylimidazole (7) and dimedone were obtained. The synthesis of the title compound 1 was achieved by reacting 2-benzoyl-3-chloro-5,5-dimethylcyclohex-2-enone (8) with ethane-1,2-diamine.     

Plant-Derived Stilbenoids as DNA-Binding Agents: From Monomers to Dimers

Stilbenoids are natural compounds endowed with several biological activities, including cardioprotection and cancer prevention. Among them, (±)-trans-δ-viniferin, deriving from trans-resveratrol dimerization, was investigated in its ability to target DNA duplex and G-quadruplex structures by exploiting NMR spectroscopy, circular dichroism, fluorescence spectroscopy and molecular docking. (±)-trans-δ-Viniferin proved to bind both the minor and major grooves of duplexes, whereas it bound the 3’- and 5’-ends of a G-quadruplex by stacking on the outer quartets, accompanied by rearrangement of flanking residues. Specifically, (±)-trans-δ-viniferin demonstrated higher affinity for the investigated DNA targets than its monomeric counterpart. Additionally, the methoxylated derivatives of (±)-trans-δ-viniferin and trans-resveratrol, i. e. (±)-pterostilbene-trans-dihydrodimer and trans-pterostilbene, respectively, were evaluated, revealing similar binding modes, affinities and stoichiometries with the DNA targets as their parent analogues. All tested compounds were cytotoxic at μM concentration on several cancer cell lines, showing DNA damaging activity consistent with their ability to tightly interact with duplex and G-quadruplex structures.     

Reactivity of terminal transition metal borylene complexes

The chemistry of terminal transition metal borylene complexes is reviewed, with particular attention to recent developments concerning the reactivity of these species. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:238–238, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20247     

Characterization by fourier transform infrared spectroscopy (FT-IR) and 2D IR correlation spectroscopy of PAMAM dendrimer

FT-IR and 2D correlation spectroscopy were employed to study the microstructural changes occurring during phase transitions of a liquid crystal poly(amidoamine) codendrimer (PAMAM (L1)16(L2)16) generation 3, functionalized on the terminal groups by one-chain promesogenic calamitic units (4-(4'-decyloxybenzoyloxy)salicylaldehyde (L1)) and two-chain promesogenic calamitic units (4-(3',4'-didecyloxybenzoyloxy)salicylaldehyde (L2)). Spectral modifications associated with molecular conformation rearrangements allowing for molecular shape change on going from a liquid-crystalline organization to another were found. The transition temperatures were calculated, and they are in good agreement with the DSC data. Spectral analysis gives evidence of the LC phase transitions and to an additional transition associated with the existence of conformers. Various types of hydrogen bonding have been established.     

Novel hetero-bimetallic metalla-macrocycles based on the bis-1-pyridyl ferrocene [Fe(eta 5-C5H(4)-1-C5H4N)2] ligand. Design,synthesis and structural characterization of the complexes [Fe(eta 5-C5H(4)-1-C5H4N)2](AgI)2(2+)/(CuII)2(4+)/(ZnII)2(4+)

The bidentate sandwich ligand [Fe(eta 5-C5H(4)-1-C5H4N)2] has been prepared, structurally characterized and employed in the preparation of the novel supramolecular heterobimetallic metalla-macrocycles [Fe(eta 5-C5H(4)-1-C5H4N)2]Ag2(NO3)(2).1.5H2O, [Fe(eta 5-C5H(4)-1-C5H4N)2]Cu2(CH3COO)(4).3H2O and [Fe(eta 5-C5H(4)-1-C5H4N)2]Zn2Cl4.     

Chiral quinuclidine-based amine catalysts for the asymmetric one-pot, three-component aza-Baylis-Hillman reaction

Chiral quinuclidine derivatives were employed as catalysts in the one-pot, three-component aza-Baylis-Hillman reaction between arylaldehydes, tosylamide and alkyl acrylates or acrylonitrile. A sterically non-hindered tricyclic derivative of quinidine was found to be the most efficient catalyst in transferring its chiral information. High conversions were ensured by using a catalytic amount of titanium isopropoxide and by the addition of molecular sieves (4 Å). The adducts formed, α-methylene-β-amino acid derivatives, were obtained in good yields (up to 95%) and in enantioselectivities up to 74%.     

Widely tunable optical parametric oscillator driven by a pulsed diode-pumped nonlinear-mirror mode-locked Nd:YAG laser

We report on the development of a pulsed diode end-pumped Nd:YAG laser mode-locked by a nonlinear mirror and stabilized by an acousto-optical modulator. With the introduction of appropriate intracavity loss, the laser is able to generate 22.8 ps pulses with the energy of 4.5 μJ. After amplification and frequency doubling stages, the second harmonic radiation is used to non-collinearly synchronously pump a β-barium borate optical parametric oscillator in a walk-off compensated scheme. The system demonstrates a wide-tuning range from 635 nm to 2.55 μm for the signal output, with maximum average conversion efficiency as high as 42%.