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Following our previous report on a novel class of C4 symmetric porphyrazines bearing 2,5-dimethylpyrrolyl and methyl(3-pyridylmethyl)amino groups in the periphery, here we report the synthesis and characterization of unsymmetrical porphyrazines with peripheral 2,5-di(2-thienyl)pyrrolyl and dimethylamino groups that break the molecular C4 symmetry. The porphyrazines were prepared via macrocyclization reactions of a dinitrile precursor. Variable-temperature 1H NMR experiments, single crystal X-ray work and UV–Vis spectra in different solvents of the unsymmetrical magnesium porphyrazine provided information on the structural and electronic features of the entire macrocyclic system. A detailed discussion of the UV–Vis spectra in different solvents emphasizes the role played by the extended peripheral 2,5-di(2-thienyl)pyrrolyl substituent. 相似文献
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Garramone G Pietrangeli D Ricciardi G Conoci S Guascito MR Malitesta C Cesari D Casilli S Giotta L Giancane G Valli L 《The journal of physical chemistry. B》2008,112(37):11517-11528
Thin films of a newly synthesized iron(III) porphyrazine, LFeOESPz ( L = ClEtO, OESPz = ethylsulfanylporphyrazine), have been deposited by the Langmuir-Schafer (LS) technique (horizontal lifting) on ITO or gold substrates. Before deposition, the floating films have been investigated at the air-water interface by pressure/area per molecule (pi/ A) experiments, Brewster angle microscopy (BAM) and UV-vis reflection spectroscopy (RefSpec). The complex reacts with water subphase (pH 6.2) forming the mu-oxo dimer, which becomes the predominant component of the LS films ( LS-Fe) as indicated by optical, IR, XPS, and electrochemical data. LS-Fe multilayers exhibit, between open circuit potential (OCP) and +0.90 V (vs SCE), two independent peak pairs with formal potentials, E surf (I) and E surf(II) of +0.56 V and +0.78 V, respectively. According to dynamic voltammetric and coulometric experiments the peak pair at +0.56 V is attributed to one-electron process at the iron(III) centers on the monomer, while the peak pair at +0.78 V is associated to a four-electron process involving mu-oxo-dimer oligomers. LS-Fe films prove to be quite stable electrochemically between OCP and +0.90 V. The electrochemical stability decreases, however, when the potential range is extended both anodically and cathodically outside these limits, due to formation of new species. Upon incubation with TCA solutions, LS-Fe films show remarkable changes in the UV-vis spectra, which are consistent with a significant mu-oxo dimer --> monomer conversion. Addition of TCA to the electrochemical cell using a LS-Fe film as working electrode, results in a linear increase of a cathodic current peak near -0.40 V as the TCA concentration varies in the 0.1-2.0 mM range. This behavior is interpreted in terms of TCA inducing a progressive change in the composition of the LS-Fe films in favor of the monomeric iron(III) porphyrazine, which is responsible for the observed increase in the cathodic current near -0.40 V. 相似文献
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Samundeeswari Mariappan Balasekaran Frederic Poineau 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(12):1613-1616
Reports of quadrivalent transition‐metal fluoride salts containing bulky organic cations are limited. In this context, we prepared the bis(tetraphenylarsonium) hexafluoridotechnetate(IV) dihydrate salt, (C24H20As)2[TcF6]·2H2O, by a cation metathesis reaction of (NH4)2[TcF6] in water. This is the first report of an arsonium salt of the hexafluoridotechnetate(IV) dianion. (AsPh4)2[TcF6]·2H2O crystallizes in the triclinic space group P. The [TcF6]2? anion adopts a slightly distorted octahedral geometry with an average Tc—F bond length of 1.933 Å. The cyclic voltammogram of (AsPh4)2[TcF6]·2H2O in CH3CN shows a one‐electron reversible oxidation wave at 1.496 V. 相似文献
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Nicholas Aberle Simon P.B. Ovenden Keith G. Watson Brian J. Smith 《Tetrahedron letters》2007,48(12):2199-2203
Synthetic efforts towards spiroleucettadine are described, including the enantioselective synthesis of the presumed biosynthetic precursor. High level density functional theory calculations were used to predict the 13C NMR shifts of possible alternative structures and, along with a re-evaluation of the available NMR data, allow the proposal of revised structures for this spirocyclic alkaloid. 相似文献
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《Journal of Coordination Chemistry》2012,65(19):3157-3167
Reaction of FeCl3 with one equivalent of acac (acac = pentane-2,4-dionate) and KTpMe2 (TpMe2 = hydrotris(3,5-dimethyl-pyrazol-1-yl)borate) yielded TpMe2Fe(acac)Cl (3), which upon reaction with methanolic solution of sodium azide resulted in the formation of a six coordinate compound TpMe2Fe(acac)N3 (4) with a single azide. When the reaction of FeCl3 and KTpMe2 was performed with two equivalents of sodium azide and one equivalent of 3,5-dimethylpyrazole (PzMe2H), a six coordinate cis azide compound [TpMe2Fe(PzMe2H)(N3)2] (5) was obtained. These compounds were characterized by spectroscopic methods and single crystal X-ray crystallography. Electrochemical studies of 5 show that it can be irreversibly reduced at relatively lower potential than 4. The photolysis of 5 was performed at 77 K at different wavelengths (480, 419, and 330 nm) showing that 5 was photoreduced to a high-spin Fe(II) species instead of photooxidized to Fe(V). 相似文献
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Koleva B Ahmed G Gutzov S Petkov I 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(2):587-591
Conventional and linear-polarized IR-spectroscopic tools based on reducing-difference procedures for non-polarized and polarized IR-spectra interpretation as well as orientation technique of solids (colloidal suspension in nematic liquid crystal) and UV/vis spectroscopy are applied for investigation of new sol-gel materials with potential optical application of doped organic dye 3-(3-(4-(dimethylamino)phenyl)propenoyl)-2H-chromen-2-one (K2) and Sm3+ ions. The results show that during aging of the monoliths Sm3+ forms an unstable complex with K2, [Sm(K2)(2)(H2O2](NO3)(3), which transforms to [Sm(H2O)(6)](3+) one, typical for gel-Sm3+ system. Quantum chemical ab initio and DFT calculations are reported with a view to support experimental IR-characteristic bands of the system studied. 相似文献
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Baxter I Ben-Haida A Colquhoun HM Hodge P Kohnke FH Williams DJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(23):4285-4296
Reaction of 4,4'-sulfonylbis(benzenethiol) with 4,4'-dichlorodiphenylsulfone under pseudo-high-dilution conditions leads to macrocyclic thioethersulfones [-S-Ar-SO2-Ar-]n (Ar = 1,4-phenylene). These include a highly strained [1+1] cyclodimer (n = 2), a cyclotrimer resulting from thioetherexchange reactions, and a [2+2] cyclotetramer which can adopt two entirely different conformations in the crystalline state, one having molecular D2d ("tennis-ball-seam") symmetry. The same type of reaction is successful using 4,4'-thiobis(benzenethiol) instead of 4,4'-sulfonylbis(benzenethiol) and affords macrocycles with a higher ratio of thioether to sulfone linkages. Exhaustive oxidation of macrocyclic thioethersulfones with hydrogen peroxide affords a series of sulfone-linked paracyclophanes, [-Ar-SO2-]4, [-Ar-SO2-]6, [-Ar-SO2-]8 and [-Ar-SO2-]12. Single crystal X-ray analysis reveals [Ar-SO2-]4 to be a near-perfect square box, whilst the cyclic hexamer [-Ar-SO2-]6 adopts a much more irregular conformation. and [-Ar-SO2-]8 displays a "double-box" structure clearly related to that of [Ar-SO2-]4. 相似文献
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Fu WF Gan X Che CM Cao QY Zhou ZY Zhu NN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(9):2228-2236
Polynuclear copper(I) complexes with bridging bis(dicyclohexylphosphino)methane (dcpm) and iodide ligands, [Cu(2)(dcpm)(2)(CH(3)CN)(2)](BF(4))(2) (1), [Cu(2)(dcpm)(2)](BF(4))(2) (2), [(CuI)(3)(dcpm)(2)] (3), [(CuI)(4)(dcpm)(2)] (4), and [(CuI)(2)(dcpm)(2)] (5) were prepared and their structures determined by X-ray crystal analysis. The shortest Cu--Cu distance found in these complexes is 2.475(1) A for 3. Powdered samples of 1, 3, 4, and 5 display intense and long-lived phosphorescence with lambda(max) at 460, 626, 590, and 456 nm and emission quantum yields of 0.26, 0.11, 0.12, and 0.56 at room temperature, respectively. In the solid state, 2 displays both a weak emission at 377 and an intense one at 474 nm with an overall emission yield 0.42. The difference in emission properties among complexes 1-5 suggests that both Cu--Cu interaction and coordination around the copper(I) center affect the excited state properties. A degassed solution of 2 in acetone gives a bright red emission with lambda(max) at 625 nm at room temperature. The difference absorption spectra of the triplet excited states of 1-5 in acetonitrile show broad absorption peaks at 340-410 and 850-870 nm. 相似文献
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Sergiy O. Nikitin Rostyslav D. Lampeka Yulian M. Volovenko Gennady V. Palamarchuk Oleg V. Shishkin 《Polyhedron》2010
A series of new 3d-metal complexes have been prepared by the reaction of M(CH3COO)2 (M = Zn(II), Co(II), Ni(II)) and 1,2-diamino-3-(2-benzothiazolyl)-4(5H)-ketopyrrole (HL) in a methanol (3) or a methanol/dmf (1, 2) medium. All the complexes have been studied by elemental analyses, electronic and IR spectroscopies. The zinc(II) complex 1 and the ligand HL have been investigated using the method of 1H NMR-spectroscopy at various temperatures. The disappearance of the signal from one proton of the amino group H(5) in the spectrum of complex 1 confirmed the existence of the ligand in the deprotonated form. According to the data of the 1H NMR-spectroscopy, the ligand HL is coordinated to zinc(II) through the nitrogen atom of the deprotonated amino group and the nitrogen atom of the benzothiazole substituent. These data are in agreement with X-ray structural studies for the ligand HL and the zinc(II) complex 1. 相似文献
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Barbara Hachuła Anna Polasz Maria Książek Joachim Kusz Violetta Kozik Marek Matussek Wojciech Pisarski 《Tetrahedron》2017,73(20):2901-2912
Several bis-terephthalamides based on methyl esters of amino acids including glycine (1), β-alanine (2), γ-aminobutyric acid (3) and ε-aminocaproic acid (4), X(CH2)nHNOCC6H4CONH(CH2)nX (XCO2CH3,n = 1, 2, 3 and 5), have been synthesized and characterized by single-crystal X-ray diffraction and spectroscopic methods: FT-IR, polarized FT-IR, Raman, 1H NMR and 13C NMR. The four structures assemble via classical NH?O hydrogen bonds between amide functionalities linking the molecules into chains parallel to the short axis. The analysis of polarized IR spectra of pure and deuterated compounds reveals that a weak interchain (“through-space”) exciton coupling involves two closely-spaced hydrogen bonds belonging to two different adjacent chains. The exciton coupling magnitude decreases with the addition of methylene groups to the terephthalamide system. Isotope effects in terephthalamides show that the distribution of protons and deuterons in the crystalline lattice depends on the strength of the exciton couplings involving hydrogen bonds. 相似文献
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《Phosphorus, sulfur, and silicon and the related elements》2013,188(11):2309-2317
Complexes of beryllium chloride and nitrate with (Me2N)2P(O)F were characterized in solution by multinuclear NMR spectroscopy and in some cases by IR spectroscopy and conductimetry. 31P and 19F NMR spectra were informative of changes associated with complex formation revealing resonances consistent with different species in solution and suggest an equilibrium between these species in both beryllium derivatives. These compounds show narrow lines in the solution 9Be NMR spectra, indicative of a highly symmetric environment for beryllium. The presence of the different species was more pronounced in beryllium chloride complexes. The results are compared to those reported in the literature for hexamethylphosphoramide (HMPA). 相似文献
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Metal-free porphyrazine and metal porphyrazinates (M = Mg, Cu, Co or Zn) substituted with eight ferrocene moieties on the periphery through flexible alkylthio-bridges have been synthesised in a multi-step reaction sequence. The new compounds have been characterised by elemental analyses, i.r., 1H- and 13C-n.m.r., u.v.–vis. and mass spectra. The electrochemical investigation of porphyrazines indicates that all the ferrocene moieties are oxidised at the same potential, confirming the lack of any interaction among ferrocene groups or between ferrocenes and the porphyrazine core. 相似文献
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《Journal of Molecular Structure》1987,157(4):329-337
The crystal structure of 1,8-bis(dimethylamino)naphthalene (DMAN) 2,4-dinitroimidazolate, C17H20N6O4, has been determined by X-ray diffraction. The crystals are monoclinic, P2 1/c, a = 13.426(4), b = 10.465(3), c = 15.915(4) », β = 126.12(4)°, Z = 4. The structure was solved by direct methods, and refined to an R value of 0.033 for 2291 non-zero independent amplitudes. The [NN⋯N]+ bridges of 2.606(3) » with ∠NHN = 160(3)° are characterized by an asymmetric proton density distribution. The IR protonic absorption is located in two regions at about 650 and 1950 cm−1 showing relatively small intensity. The isotopic ratio ν(NHN/ν(NDN) for the low frequency region is almost unity. It seems that hydrogen bonds in protonated DMAN are characterized by a flat asymmetric single minimum potential for the proton motion. 相似文献