Ralf Petri  Claudia Schmidt‐Dannert 《Angewandte Chemie (International ed. in English)》2004,43(15):1908-1908

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Höbartner C  Mittendorfer H  Breuker K  Micura R 《Angewandte Chemie (International ed. in English)》2004,43(30):3922-3925

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Cappitelli F  Zanardini E  Sorlini C 《Macromolecular bioscience》2004,4(4):399-406

Synthetic resins have been extensively employed by artists in their works of art, e.g. as paint binders, or by conservators for conservation treatments, e.g. as stone consolidants and protectives. It is generally thought that synthetic resins are less prone to chemical, physical and biological deterioration than other organic products but there are many articles in the scientific literature and some reports in the conservation of cultural heritage literature claiming that microorganisms are capable of degrading synthetic resins. This paper reviews the researches on the biodeterioration of synthetic resins used in the conservation of cultural heritage, including stone, painting and textile materials, carried out in the last fifty years.  相似文献   

    

Giuliana Gervasio  Domenica Marabello  Claudia Barolo  Pierluigi Quagliotto  Guido Viscardi 《Journal of heterocyclic chemistry》2003,40(1):129-133

The X‐ray analyses of some neutral and cationic derivatives of 2‐(4‐methylpyridin‐2‐yl)‐1H‐benzimida‐zole are reported and the structural data tentatively correlated to relative UV‐visible properties. A rotation of the γ‐picoline ring with respect to the benzimidazole moiety may be responsible of the spectral behavior.  相似文献   

    

Ermanno Barni  Claudia Barolo  Pierluigi Quagliotto  Piero Savarino  Guido Viscardi  Domenica Marabello 《Journal of heterocyclic chemistry》2003,40(4):649-654

A selected series of 2‐(4‐methylpyridin‐2‐yl)‐1H‐benzimidazole derivatives, bases and cyclic mono‐ and bis‐salts, were synthesized. Complete ^'1H nmr characterization is reported. Ambiguous assignments were solved using ¹H‐¹H NOESY analysis. Significant ir and ¹H nmr data are presented concerning: i) tautomeric equilibrium of imidazole hydrogen; ii) hydrogen bonds; iii) conformational inversion of partially saturated rings.  相似文献   

    

A. Claudia Stückl  Franz Rau  Richard Weihrich 《无机化学与普通化学杂志》2003,629(10):1812-1824

In the present study the synthesis of metastable alloys of the noble metal Au and the semimetal Sb is realized by using high pressure techniques. The influence of Au on bulk Sb is shown experimentally by stepwise substitution. In addition to the effect of the most electronegative noble metal on Pauling's scale in the binary Au‐Sb phases, some ternary compounds with In, Sn, As, and Te in addition to Au and Sb are discussed. The experiments are planned to obtain a better knowledge on the reasons for building up a simple cubic Sb partial lattice, and their crystallographic results are used to construct model structures for new electronic structure calculations from first principles on the metastable π‐phases. Using the LCAO‐CO ansatz and density‐functional methods, we study total energies, band structures, densities of states and charge transfer properties according to Bader's method by integrating zero flux surfaces. Finally, from electronic band structure analysis, the quantities “chemical potential” μ, and “chemical hardness”, η, are derived according to the original ideas of Pearson and Parr and are applied to solid state problems using special points of the Brillouin zones within a band structure approximation for the first time. The results are shown to support the experimental findings about the substitution path within the system Au‐Sb.  相似文献   

Förster-type energy transfer along a specified axis     

Minkowski C  Calzaferri G 《Angewandte Chemie (International ed. in English)》2005,44(33):5325-5329

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Fenske D  Anson CE  Eichhöfer A  Fuhr O  Ingendoh A  Persau C  Richert C 《Angewandte Chemie (International ed. in English)》2005,44(33):5242-5246

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Ahlrichs R  Fenske D  McPartlin M  Rothenberger A  Schrodt C  Wieber S 《Angewandte Chemie (International ed. in English)》2005,44(25):3932-3936

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Claudia Bueno  Juan Guerrero  María&#x;Victoria Encinas 《Helvetica chimica acta》2004,87(4):940-948

The photophysical properties and acid/base equilibria of 4‐pyridoxic acid (=3‐hydroxy‐5‐(hydroxymethyl)‐2‐methylpyridine‐4‐carboxylic acid), the final product of the catabolism of vitamin B₆, have been studied in aqueous solutions. The ground state of 4‐pyridoxic acid exhibits the different protonated forms A – D in the range of H₀=?6 to pH 11.5. HMQC‐ and HMBC‐NMR Studies allowed the pH‐dependent assignment of the different C‐atoms, and the evaluation of the deprotonation sequence. The 3‐OH group in the ground state has a ‘pK_a’ of H₀=?0.64, which is much lower than that found for other vitamin B₆ related compounds. The pK_a value of the 4‐COOH group is 5.4. Fluorescence studies showed that the same species exist at the lowest excited singlet state, but in different pH ranges. The 3‐OH group is four pH units more acidic in the lowest excited singlet state than in the ground state. Excitation spectra and emission decays in the pH range of 8 to 11.5 indicate that the pyridine N‐atom is more basic in the excited singlet state than in the ground state. The emission spectra are red‐shifted in protic solvents, in agreement with an intramolecular H‐bond between the ionized 3‐OH group and the nonionized 4‐COOH group.  相似文献