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31.
Mauro Ghedini Daniela Pucci Alessandra Crispini Iolinda Aiello Francesco Barigelletti Alessandro Gessi Oriano Francescangeli 《应用有机金属化学》1999,13(8):565-581
The series of dinuclear 4,4′‐bis(hexyloxy)azobenzene, [H(Azo‐6)], cyclopalladated complexes of general formula [Azo‐6)Pd(µ‐X)]2, (X = Cl, Br, I, N3, SCN, OAc) and [Azo‐6)2Pd2(µ‐Ox)] (Ox = oxalate) have been synthesized and investigated for mesomorphism and spectroscopic properties. Single‐crystal X‐ray analysis of the dinuclear bromo‐ and iodo‐bridged complexes has been performed. The structural data, compared with those of the known homologous chloro compound, show that all the [Azo‐6)Pd(µ‐X)]2)] (X = Cl, Br, I) molecules crystallize in the monoclinic space group P21/c and are isomorphous. They are arranged in slipped pairs with intermolecular non‐bonding Pd–Pd contacts ranging from 3.668(1) Å(X = Cl) to 3.758(3) Å(X = I). The different nature of the bridging group allows variation of the distance between the palladium atoms and the bond environment experienced by the metal centers. Thus, this comparative study reveals that the effectiveness of the bridging group in promoting thermotropic mesophases is greater for chloride, bromide, azide or oxalate than for iodide, thiocyanate or acetate. The greatest range of liquid‐crystal behavior was displayed by [Azo−6)2Pd2(µ−Ox)]. Remarkably, this compound is the first example of a metallomesogen containing the bridging oxalate group. The bimetallic complexes exhibit different absorption spectra (i.e. colors) depending, in general terms, on the nature of the bridge connecting the two cyclometalated [H(Azo‐6)] moieties, which can be varied so as to tune the optical properties. Blocking the azo group in the trans position results in several cases in weakly luminescent complexes, with luminescence efficiencies ϕ ≈10−4 and luminescence lifetimes of the order of nanoseconds. Using the data obtained from the 4,4′‐bis(hexyloxy)azoxybenzene [H(Azoxy‐6)] derivative, [Azoxy‐6)Pd(µ<?tf="ps2b61">‐Cl)]2, from the mononuclear acetylacetonate (acac) complexes [(Azo‐6)Pd(acac)] and [(Azoxy‐6)Pd(acac)], and from the uncomplexed [H(Azo‐6)] and [H(Azoxy‐6)] ligands, the nature of the excited states relevant to the photophysical behavior are discussed. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
32.
Oemrawsingh SS Ma X Voigt D Aiello A Eliel ER 't Hooft GW Woerdman JP 《Physical review letters》2005,95(24):240501
The singular nature of a noninteger spiral phase plate allows easy manipulation of spatial degrees of freedom of photon states. Using two such devices, we have observed very high-dimensional spatial entanglement of twin photons generated by spontaneous parametric down-conversion. 相似文献
33.
We analyze an experimental setup in which a quasi-monochromatic spatially coherent beam of light is used to probe a paraxial optical scatterer. We discuss the effect of the spatial coherence of the probe beam on the Mueller matrix representing the scatterer. We show that, according to the degree of spatial coherence of the beam, the same scattering medium can be represented by different Mueller matrices. This result should serve as a warning for experimentalists. 相似文献
34.
Experimental results on light depolarization due to multimode scattering are reported. By means of polarization tomography, we characterize the depolarizing power and the polarization entropy of a broad class of optically scattering media and confirm the recently predicted universal behavior of these two quantities [Phys. Rev. Lett. 94, 090406 (2005)]. 相似文献
35.
Summary We describe a photometer which uses a3He-cooled bolometer working in the millimetric atmospheric window, aimed at a program of observations of galactic and extra-galactic
sources. We also give an account of the results obtained during the January 1988 run at the TIRGO telescope.
To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee. 相似文献
36.
E. Aiello G. Dattolo G. Cirrincione S. Plescia G. Daidone 《Journal of heterocyclic chemistry》1978,15(4):537-539
A new synthesis of pyrrolo[3,2-b] pyridine starting with pyrrole ring is described. The procedure allows the synthesis of 4-azaindoles bearing a sensitive group at C-7. The nitration of 4b with nitric acid and acetic anhydride at ?15° gave 5 . The hydrogenation of 5 led to simultaneous reduction of N-hydroxy and nitro groups and to hydrogenolysis of the isoxazole nucleus, affording an appropriate chain of atoms to building up the pyrrolo[3,2-b] pyridine ring. 相似文献
37.
We propose a novel setup to investigate the entanglement of orbital angular momentum states living in a high-dimensional Hilbert space. We incorporate noninteger spiral phase plates in spatial analyzers, enabling us to use only two detectors. The two-photon states that are produced are not confined to a 2 x 2-dimensional Hilbert space, and the setup allows the probing of correlations in a high-dimensional space. For the special case of half-integer spiral phase plates, we predict that the Clauser-Horne-Shimony-Holt-Bell parameter S is larger than achievable for two qubits (S=2 sqrt[2]), namely, S=31 / 5. 相似文献
38.
This Letter reports an experimental and theoretical study of the response of a quadrant detector (QD) to an incident vortex beam, specifically a Laguerre-Gaussian (LG) beam. We have found that the LG beam response depends on the vorticity index ?. We compare LG beams with hard-ringed beams and find that at higher ? values, the QD response to LG beams can be approximated by its response to hard-ringed beams. Our findings are important in view of the increasing interest in optical vortex beams. 相似文献
39.
Girolamo Cirrincione Anna Maria Almerico Enrico Aiello Gaetano Dattolo Stefania Grimaudo Patrizia Diana 《合成通讯》2013,43(12):1627-1631
The 3-triazenopyrroles, a new class of pyrrole derivatives, were synthesized in quantitative yield by coupling 3-diazopyrroles with secondary amines. 相似文献
40.
Annarella Costanzo Fabrizio Bruni Gabriella Guerrini Silvia Selleri Petra Malmberg Aiello Claudia Lamberti 《Journal of heterocyclic chemistry》1992,29(6):1499-1505
The synthesis of derivatives of pyrazolo[1,5-a]pyrrolo[1,2-c][1,3,6]benzotriazocine was obtained by the reaction of arylaldehydes with some 1-(2-aminophenyl)-5-(pyrrol-1-yl)pyrazoles, as hydrochlorides. Characterization of this new class of compounds was effected with ir, pmr and 13C nmr spectral data. 相似文献