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81.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. 相似文献
82.
Dr. Iciar Uriarte Dr. Felipe Reviriego Dr. Camilla Calabrese Prof. José Elguero Prof. Zbigniew Kisiel Prof. Ibon Alkorta Dr. Emilio J. Cocinero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(43):10172-10178
Bond length alternation is a chemical phenomenon in benzene rings fused to other rings, which has been mainly predicted theoretically. Its physical origin is still not clear and has generated discussion. Here, by using a strategy that combines microwave spectroscopy, custom-made synthesis and high-level ab initio calculations, we demonstrate that this phenomenon is clearly observed in the prototype indazole molecule isolated in the gas phase. The 1H-indazole conformer was detected by rotational spectroscopy, and its 17 isotopologues resulting from single and double heavy atom substitution (13C and 15N) were also unambiguously observed. Several experimental structures were determined and, in particular, the most useful semi-experimental equilibrium structure (reSE), allowed determination of the heavy atom bond lengths to milli-Ångstrom precision. The experimentally determined bond length alternation is estimated to correspond to 60:40 contributions from the two resonant forms of 1H-indazole. 相似文献
83.
Nicola Monti Stefano Zacchini Massimiliano Massi Alejandro Hochkoeppler Loris Giorgini Valentina Fiorini Alessandra Stefan Stefano Stagni 《应用有机金属化学》2020,34(9):e5806
Herein, we describe a new family of tris chelate homoleptic Ru (II) complexes, [Ru(N^N) 3 ] 2+ , where the role of the diimine-type ligands (N^N) was fulfilled by 2-pyridyl (PTZ) or 2-quinolyl tetrazole (QTZ) derivatives decorated with various alkyl substituents at the N-2 position of the tetrazole ring. The new Ru (II) complexes with general formula [Ru (PTZ-R) 3 ] 2+ and [Ru (QTZ-R) 3 ] 2+ , were obtained as mixtures of facial (fac) and meridional (mer) isomers, as suggested by NMR (1H, 13C) experiments, and confirmed in the case of mer-[Ru (QTZ-Me) 3 ] 2+ , by X-ray crystallography. The photophysical behavior of the tetrazole-based [Ru(N^N) 3 ] 2+ type species was investigated by UV–vis absorption spectroscopy, providing trends typical of polypyridyl Ru (II) complexes. The new homoleptic complexes fac/mer- [Ru (PTZ-R) 3 ] 2+ and fac/mer- [Ru (QTZ-R) 3 ] 2+ have been assessed for any eventual antimicrobial activity towards two different bacteria such as Gram-negative Escherichia coli and Gram-positive Deinococcus radiodurans. Whereas being inactive toward E. coli, the response of agar disks diffusion tests suggested that some of the new fac/mer Ru (II) complexes could inhibit the growth of D. radiodurans. This effect was further investigated by determining the growth kinetics in liquid medium of D. radiodurans exposed to the fac/mer- [Ru (PTZ-R) 3 ] 2+ and fac/mer- [Ru (QTZ-R) 3 ] 2+ complexes at different concentrations. The outcome of these experiments highlighted that the turn-on of the growth inhibitory effect took place as the linear hexyl chain was appended to the PTZ or QTZ scaffold, suggesting also how the inhibitory activity appeared more pronouncedly exerted by the facial isomers fac- [Ru (PTZ-Hex) 3 ] 2+ and fac- [Ru (QTZ-Hex) 3 ] 2+ (MIC = ca. 3.0 μg/ml) with respect to the corresponding meridional isomers (MIC = ca. 6.0 μg/ml). 相似文献
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P. Costa Bizzarri C. Della Casa M. Fiorini W. Porzio 《Journal of polymer science. Part A, Polymer chemistry》1988,26(1):255-265
Oligomers containing thianthrene units in the chain are synthesized by AlCl3-catalyzed reaction of diphenylsulfide, thianthrene, poly(p-phenylene sulfide), and poly(m-phenylene disulfide) with sulfur at 80°C. The products are compared with that obtained by the reaction of diphenylsulfide with AlCl3 at 225°C. IR spectra and elemental analyses are consistent with cyclic chain structures and show a higher cyclization for CHCl3-insoluble fractions. X-ray diffraction analysis indicates the same structure for the samples obtained with the different methods of synthesis. A possible structural model is tentatively proposed. 相似文献
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88.
A strong enhancement of the two-photon absorption (TPA) cross section of tetrakis(4-sulfonatophenyl)porphyrin diacid (H(4)TPPS(2-)) at various wavelengths when a J-type aggregate is formed in water with respect to the one observed for the H(4)TPPS(2-) monomer in a mixture of water, dimethyl sulfoxide (DMSO), and urea is presented. The TPA properties are characterized by the open aperture Z-scan technique and the ultrafast two-photon absorption spectroscopy with white light continuum probe (TPA-WLCP) technique. The observed enhancement is discussed in terms of possible electronic cooperative effects in the aggregate. 相似文献
89.
90.
Supramolecular ordering happens as an important parameter for the control of light emission processes. In this review paper,
we discuss several examples of application of self-assembly to the realization of nano-structures designed in view of mastering
specific photonic processes. This comprises the formation of highly localized plasmon modes in self-organized 2D assemblies
of metal nanoparticles, the immobilization of dyes inside highly homogeneous 2D alveolar self-assembled molecular matrices
and molecular 3D building blocks designed to combine in-plane periodicity and off-plane π-conjugated protrusions. Finally,
we will discuss 3D self-assembly in solution with the example of fluorescent labelling of DNA. 相似文献