1,721,027 research outputs found
STRUCTURAL REINVESTIGATION OF THE ALPHA AND BETA FORMS OF COBALT PHTALOCYANINE AND KINETICS OF THE ALPHA -> BETA TRANSITION AS STUDIED BY THE EDXD TECHNIQUE
No full textNovel families of phthalocyanine-like macrocycles—Porphyrazines with annulated strongly electron-withdrawing 1,2,5-thia/selenodiazole rings
No full textTetrakis(thiadiazole)porphyrazines and tetrakis(selenodiazole)porphyrazines, first described in the years 1998–2001, have later attracted the attention of different scientific groups in the world. Since the beginning and in the most recent times, a number of aspects concerning their relevance as phthalocyanine-like macrocycles, their distinct structural, electronic and UV–visible spectroscopic features, and electrochemical behavior have brought to knowledge the important role played by the externally annulated electron-withdrawing thia- and selenodiazole rings. Much has been learned about the acid–base properties of the new macrocycles, their facile electron uptake and negative charge redistribution capability within the entire macrocyclic framework. Further work has been directed to the synthesis and characterization of several low-symmetry species carrying peripherally annulated benzene or substituted benzene rings and thia- or selenodiazole rings and the structural and electronic effects caused by the progressive annulation of the heterocyclic rings in a basic phthalocyanine structure has been examined. Deselenation processes at the annulated selenodiazole rings in symmetrical and low-symmetry macrocycles and the formation of vicinal diamino functionalities have allowed diversified derivatization procedures with formation of new porphyrazine macrocycles by ring reclosure or designed external sites for exocyclic metalation in dinuclear species
NUOVI COMPLESSI DI Pd(II) DI TIPO PORFIRAZINICO MONO- E PENTAMETALLICI COME FOTOSENSIBILIZZATORI IN SOLUZIONE DI DIMETILFORMAMMIDE PER LA PRODUZIONE DI OSSIGENO DI SINGOLETTO, 1O2.
No full textdepositat
Experimental and Theoretical Study of Basic Properties of tert-Butylsubstituted Tribenzo(1,2,5-thiadiazolo)porphyrazines.
No full textOne Step Forward to "Stapled" Bis(phthalocyanine) Metal Complexes: Synthesis, Characterization, and Redox Properties of Bis(phthalocyaninato)niobium(IV). X-ray Crystal Structure of the Monoelectronically Oxidized Species [Pc2Nb](I3)(I2)0.5(ClNP) 3.5 (ClNP = 1-Chloronaphthalene)
No full textBis(phthalocyaninato)niobium(IV) has been prepared and isolated as a monosolvate, [Pc2Nb]-ClNP (ClNP = 1-chloronaphthalene). It is a light-brown, stable-to-air Nb(IV) (d1) paramagnetic sandwich-like species, which, upon oxidation by I2 under mild conditions, undergoes a metal-centered monoelectronic oxidation to give the diamagnetic Nb(V) (d0) [Pc2Nb]+ fragment, with formation of saltlike species of formula [Pc2Nb](I3)(I2)0.5-(ClNP)3.5 (I). The structure of I has been elucidated by single-crystal X-ray work. Crystals are triclinic: formula C64H32N16Nb·I 3·0.5I2·3.5C10H7Cl, M = 2194.8. a = 17.702(3) Å, b = 18.708(3) Å, c = 13.504(2) Å. V= 4267.5-(13) Å3, α= 106.00(2)°, β= 93.39(2)°, γ = 83.26(1)°, Z = 2, space group P1̄. The structure of the [Pc2Nb]+ fragment, "stapled" by two inter-ligand C-C σ bonds (C11A-C11B and C31A-C31B = 1.574(15) Å), together with its color and UV-visible spectral behavior, allows a straightforward assignment of the same "stapled" structure to the unoxidized [Pc2Nb]. The present niobium sandwiched materials reiterate the peculiar structural findings shown only by the previously reported [Pc2Ti]
Further Structural Information on the Intra- and Interunit Contacts in Dimeric Ruthenium Phthalocyanine
No full textPrevious EXAFS and further LAXS studies fully confirm that solid amorphous ruthenium phthalocyanine, as obtained from its DMSO, pyridine, and isoquinoline adducts, is dimeric with dimers chained to form aggregates of formula [(PcRu)(2)](n) (average n = 6) and with short intradimer Ru-Ru (2.40 Angstrom) and long interdimer (4.30-4.40 Angstrom) bond distances, in contrast with recent different EXAFS findings (very short Ru-Ru interdimer contacts, 3.52 Angstrom) and an associated structural model
Complessi mono e pentametallici di tipo porfirazinico come fotosensibilizzatori in campo farmaceutico
No full textDimeric Osmium Phtalocyanine Organized in Discrete Columnarly Stacked Assemblies: Structure, Magnetism, and Electrical Conductivity Properties
No full textSolid pure osmium phthalocyanine, as obtained from its adduct [PcOs(py)(2)], is an air-stable solid amorphous material. Its structure has been examined by the wide-angle X-ray scattering (WAXS) technique. Experimental data are best fitted by assuming the molecule to consist of a dimeric unit, (PcOs)(2), held together by a direct metal-metal linkage. The short Os-Os distance (2.38(1) Angstrom) is consistent with the presence of a double bond between the two Os(II) atoms. Each Pc skeleton has a domed conformation with displacement of the respective Os atom from the plane of the four coordinating nitrogen atoms (0.40 Angstrom) toward the other Os atom. The solid-state structure consists of disordered couples of parallel chains of (PcOs)(2). On average, six dimeric units are aligned along the stacking direction within each chain. The relative orientation of the two intradimer Pc units is 30 degrees, eclipsing occurring for the interdimer adjacent Pc units along the chain. Magnetic susceptibility measurements in the temperature range 5-300 K indicate a strong spin-spin coupling for the two metal centers in the dimer and suggest an electronic energy level sequence sigma(2)pi(4)delta(2)delta(*2)pi(*2) and a nonmagnetic ground state for the complex, Room-temperature electrical conductivity measurements show a sigma(RT) value of 1 x 10(-5) Omega(-1) cm(-1)
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