可溶性汞化苯乙烯－丙烯酸甲酯共聚物的合成

用自由基溶液降合方法制备一系列苯乙烯－丙烯酸甲酯线型共聚物，用核磁共振测定了苯基在共聚物中的百分比，在该共聚物的四氢呋喃溶液中，用三氟乙酸汞在共聚物的苯环上进行亲电取代反应，得到可溶性汞化共聚物，由于这类泵化共的可溶于四氢呋喃，二氯甲烷等溶剂，用重沉淀法多次提纯，得到了纯度很高，溶解性较好的含重金属二价汞的共聚物，用红外光谱仪测定共聚物上的汞基团，用原子吸收定量测试共聚中的汞的百分聚代率，结果表明     

Self-propagating assembly of a molecular-based multilayer

Accelerated growth of a molecular-based material that is an active participant in its continuing self-propagated assembly has been demonstrated. This nonlinear growth process involves diffusion of palladium into a network consisting of metal-based chromophores linked via palladium.     

Measurement of the 20 and 90 keV resonances in the 18O(p,alpha)15N reaction via the Trojan horse method

The 18O(p,alpha)15N reaction is of primary importance in several astrophysical scenarios, including fluorine nucleosynthesis inside asymptotic giant branch stars as well as oxygen and nitrogen isotopic ratios in meteorite grains. Thus the indirect measurement of the low energy region of the 18O(p,alpha)15N reaction has been performed to reduce the nuclear uncertainty on theoretical predictions. In particular the strength of the 20 and 90 keV resonances has been deduced and the change in the reaction rate evaluated.     

High pressure experiments on AlxGa1−xAs-GaAs quantum-well heterostructure lasers

Hydrostatic pressure experiments on Al_xGa_1?xAsGaAs quantum-well heterostructure (QWH) laser diodes are described. Data are presented giving ～11.5meV/kbar for the bandgap vs. pressure coefficient at lower pressures, with a change to 8.5–9meV/kbar at higher pressures. We suggest that this behavior is caused by biaxial and shear stresses in the active region induced by doping or composition mismatch relative to the confining layers, or between the n and p confining layers themselves. A model consistent with the experimental data is presented.     

A New Water Soluble Calixarene: 5,11,17,23-tetrasulphonato-25,27-di(hydroxycarbonylmethoxy)-26, 28-dihydroxycalix[4]arene. A Thermodynamic and Spectroscopic Investigation of Its Proton and Copper(II) Complexes

A new water soluble receptor 5,11,17,23-tetrasulphonato-25,27-di(hydroxycarbonylmethoxy)-26,28-dihydroxycalix[4]arene was synthesized andcharacterized and its proton and copper(II) complexes were studied andcompared with the analogous species of the fully carboxylated ligand5,11,17,23-tetrasulphonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)calix[4]arene. H° and S° values are crucial for understanding thepeculiar acid-base properties of the ligand. EPR spectra together with theUV-VIS spectral data reveal the coordination stereochemistry of thecopper(II) species.     

On the Traceability of the Hazelnut Production Chain by Means of Trace Elements

The production chain of hazelnuts has been studied by analyzing three sets of samples produced in purity from three different pools of hazelnuts of cultivar “Tonda Gentile Trilobata”, “Tonda Gentile Romana” and “Mortarella”, all cultivated in Italy. From each pool, five processed products were obtained: roasted hazelnuts, hazelnut paste, hazelnut cream, Gianduja paste and Gianduiotto paste. After pre-treatment by means of dry ashing, all samples from each cultivar, including raw hazelnuts, were then analyzed by means of Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES) and Inductively Coupled Plasma–Mass Spectrometry (ICP-MS). A good discrimination was obtained among the different chain stages according to the distribution of the trace elements, as expected. More interesting was the discrimination among the different cultivars: it was possible to distinguish the samples produced from the respective cultivar by means of specific chemical markers, particularly Mo and Ni.     

Noncovalent synthesis in aqueous solution and spectroscopic characterization of multi-porphyrin complexes

The interactions of the tetracationic meso-tetrakis(N-methyl-4-pyridyl)porphyrin (H(2)TMPyP) and its metallo derivatives (MTMPyP) (where M=copper(II), zinc(II), and gold(III) with the octa-anionic form (at neutral pH) of 5,11,17,23-tetrasulfonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)calix[4]arene (C(4)TsTc) lead to a series of complex species whose stoichiometry and porphyrin sequence can be easily tuned. Crystallographic, spectroscopic, and diffusion NMR studies converge towards a common picture in which a central 1:4 porphyrin/calixarene unit serves as a template for the formation of more complex species. These species arise by successive, stepwise addition of single porphyrin molecules above and below the plane of the 1:4 central core to ultimately give a 7:4 complex. Noticeably, the stoichiometry of the various complex species corresponds to the actual concentration ratio of porphyrins and calixarenes in solution allowing the stoichiometry of these species to be easily tuned. This behavior and the remarkable stability of these species allow homo-porphyrin and hetero-(metallo)porphyrin species to be formed with control of not only the stoichiometry but also the sequence of the porphyrin array. The flexibility and ease of this approach permit, in principle, the design and synthesis of porphyrin arrays for predetermined purposes. For example, we have shown that it is very easy to design and obtain mixed porphyrin species in which a foreseen photoinduced electron-transfer is indeed observed.     

Electronic Structure of Bis(2,4-pentanedionato-O,O')oxovanadium(IV). A Photoelectron Spectroscopy, Electronic Spectroscopy, and ab Initio Molecular Orbital Study

The electronic structure of the title VO(acac)(2) complex has been investigated using effective core potential configuration interaction ab initio calculations, UV-photoelectron spectroscopy, and electronic spectroscopy. The metal-ligand bonding with the equatorial acac(-) ligands is dominated by sigma interactions involving the filled ligand orbitals and the empty orbitals of the d(1) vanadium(IV) ion. The oxovanadium interactions involve a larger metal-d participation thus resulting in a strong V-O bonding having partial triple-bond character. Additional three-orbital-four-electron stabilizing interactions involving the filled acac(-) MOs and the oxovanadium orbitals further reinforce both the axial and equatorial bonds. The unpaired metal-d electron is completely localized in the nonbonding d(x)()()2(-)(y)()()2 orbital. The low ionization energy of the photoelectron spectrum has been fully assigned on the basis of combined DeltaSCF and configuration interaction calculations. The same theoretical approach has, in addition, provided a good fitting of frequencies associated with "d-d" and charge transfer electronic transitions.