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1.
Multiporphyrinic assemblies were quantitatively formed, in one step, from a gable‐like zinc(II) bis‐porphyrin ZnP2 and free‐base porphyrins bearing pyridyl groups. The different fragments are held together by axial 4′‐N(pyridyl)–Zn interactions. Formation of a macrocycle ZnP2?(4′‐cisDPyP) and a bis‐macrocycle (ZnP2)2?(TPyP) is discussed. The macrocycle and the bis‐macrocycle were crystallized and studied by X‐ray diffraction, which confirmed the excellent complementarity between the various components. Spectrophotometric and spectrofluorimetric titrations and studies reveal high association constants for both multiporphyrinic assemblies due to the almost perfect geometrical match between the interacting units. As expected, energy transfer from the zinc porphyrin component to the free‐base porphyrin quenches the fluorescence of the zinc porphyrin components in both compounds. But while in ZnP2?(4′‐cis DPyP) sensitization of the emission of the free‐base porphyrin was observed, in (ZnP2)2?(TPyP) excitation of the peripheral Zn porphyrin units does not lead to quantitative sensitization of the luminescence of the free‐base porphyrin acceptor. An unusual HOMO–HOMO electron transfer reaction from ZnP2 to the excited TPyP unit was detected and studied.  相似文献   

2.
Excitation of the peripheral Zn porphyrin units in a noncovalent five‐porphyrin array, formed by gable‐like zinc(II) bisporphyrins and a central free‐base meso‐tetrakis(4‐pyridyl)porphyrin in a 2:1 ratio, ( ZnP2 )2? ( TPyP ), does not lead to a quantitative sensitization of the luminescence of the free‐base porphyrin acceptor, even though there is an effective energy transfer. Time resolution of the luminescence evidences a quenching of TPyP upon sensitization by the peripheral ZnP2 . The time evolution of the TPyP fluorescence in the complex can be described by a bi‐exponential fitting with a major component of 180 ps and a minor one of 5 ns, compared to an isolated TPyP lifetime of 9.4 ns. The two quenched lifetimes are shown to be correlated to the presence of 2:1 and 1:1 complexes, respectively. No quenching of TPyP fluorescence occurs in ( ZnP2 )2?( TPyP ) at 77 K in a rigid solvent for which only an energy‐transfer process (τ=150±10 ps) from peripheral ZnP2 to the central TPyP is observed. An unusual HOMO–HOMO electron‐transfer reaction from ZnP2 to the excited TPyP units, responsible for the observed phenomena, is detected. The resulting charge‐separated state, ( ZnP2 )+2?( TPyP )? is found to recombine to the ground state with a lifetime of 11 ns.  相似文献   

3.
Spectrophotometric titration and computer simulation were used to study how the nature of porphyrin and extra ligand affect the formation of extra complexes of zincporphyrins in o-xylene. The compounds under study were zincporphyrins (ZnP) with different substituents and phenyl radicals in meso-positions (zinc-5,15-(p-butyloxyphenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetraethylporphyrin (ZnP1), zinc-5,15-(p-butyloxyphenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetrabutylporphyrin (ZnP2), zinctetraphenylporphine (ZnP3), and zinc complexes with overlapped porphyrin (ZnP4). N-Methylimidazole, imidazole, pyridine, 3,5-dimethylpyrazole, and dimethylformamide were used as extra ligands (L). The strength of Zn–L bonding was found to decrease in extra complexes (L)ZnP in the series of ZnP as follows: ZnP4> ZnP1> ZnP2> ZnP3. It was established that the stability constant (logK st) for sterically nonstressed complexes (L)ZnP4linearly increases with growth in the extra ligand basicity (log ) and is proportional to the shift of the main absorption bands () in the electronic spectra of extra complexes of zinctetraphenylporphine. For spatially distorted (L)ZnP1, (L)ZnP2, and (L)ZnP3, the values of logK stand log , as well as logK stand , change symbatically. The geometric structure and energy characteristics of pentacoordinated zincporphyrins were calculated by quantum-chemical methods. Correlations were established between the calculated values of the energy of the interaction of the central metal atom with the extra ligand molecule and the stability of the extra complexes of zincporphyrins.  相似文献   

4.
In this work, two new self-assemblies based on zinc porphyrins substituted at the meso-positions with different donor units (denoted as ZnP1 and ZnP2) and anchor porphyrin (ZnPA) dyads formed by the coordination bonds of Zn-to-ligand have been prepared. Further, the assemblies were absorbed on semiconducting TiO2 electrode surfaces by the carboxylic groups of anchor porphyrin (ZnPA), and their photovoltaic performances in solar cells were performed under 100 mW cm?2 AM 1.5G sunlight. Photoelectrochemical studies reveal a significantly improved photovoltaic behavior for the dyad of triphenylamine-based zinc porphyrin (ZnP1) compared to the dyad with trimethylamine-based zinc porphyrin. The results were verified by electrochemical impedance spectroscopy, calculations, and optical performance. In addition, the modes of the assemblies immobilized on TiO2 electrode surfaces were also verified by transmission electron microscopy.  相似文献   

5.
Two new self-assemblies based on zinc porphyrin dyes ZnPx-ZnPA (x?=?1, 2) were synthesized and used for dye-sensitized solar cells. Capping layer dyes consist of zinc porphyrin (ZnP) as core unit and carbazole (P1), phenothiazine (P2) as electron-donating group. The dye ZnPA contains carboxylic group as an anchor porphyrin with upper dyes (denoted as ZnP1 and ZnP2) formed dyads by coordination bonds of Zn-to-ligand self-assembled devices. The assembly modes were also verified by transmission electron microscopy (TEM). The influence of the upper porphyrins on molecular structure as well as photovoltaic performance was investigated via photophysical and electrochemical studies and calculations. With addition of the phenothiazine unit, the ZnP2-ZnPA possesses better light-harvesting capability with a significantly red-shifted Q-band. The photoelectrochemical efficiencies for ZnP2-ZnPA are better than those of ZnP1-ZnPA ascribed to larger Jsc and Voc.

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6.
We have designed a self-assembly ZnP-ZnPA, based on a porphyrin ZnP bearing 1,3,5-triazine-2,4-diamine unit, and anchoring porphyrin ZnPA. The assembly with ZnP-ZnPA was immobilized on nanostructured TiO2 electrode surfaces. The assembled structures were characterized by transmission electron microscopy. The optical, photovoltaic, electrochemical impedance spectroscopy, and incident photon-to-current conversion efficiency were measured. The results revealed that the ZnP-ZnPA device had better photovoltaic performance than ZnPA and possessed a higher shortcircuit photocurrent density (JSC = 6.04) but a lower open-circuit photovoltage (VOC = 0.51) than anchoring ZnPA. Moreover, our previously reported assembly (ZnP-A1) as reference, the assembly device ZnP-ZnPA had better η (2.24%) and FF (72.7%).  相似文献   

7.
The novel Zintl phase dibarium zinc diphosphide (Ba2ZnP2) was synthesized for the first time. This was accomplished using the Pb flux technique, which allowed for the growth of crystals of adequate size for structural determination via single‐crystal X‐ray diffraction methods. The Ba2ZnP2 compound was determined to crystallize in a body‐centered orthorhombic space group, Ibam (No. 72). Formally, this crystallographic arrangement belongs to the K2SiP2 structure type. Therefore, the structure can be best described as infinite [ZnP2]4? polyanionic chains with divalent Ba2+ cations located between the chains. All valence electrons are partitioned, which conforms to the Zintl–Klemm concept and suggests that Ba2ZnP2 is a valence‐precise composition. The electronic band structure of this new compound, computed with the aid of the TB–LMTO–ASA code, shows that Ba2ZnP2 is an intrinsic semiconductor with a band gap of ca 0.6 eV.  相似文献   

8.
A ruthenium complex, porphyrin sensitizer, fullerene acceptor molecular pentad has been synthesized and a long‐lived hole–electron pair was achieved in aqueous solution by photoinduced multistep electron transfer: Upon irradiation by visible light, the excited‐state of a zinc porphyrin (1ZnP*) was quenched by fullerene (C60) to afford a radical ion pair, 1,3(ZnP.+‐C60.−). This was followed by the subsequent electron transfer from a water oxidation catalyst unit (RuII) to ZnP.+ to give the long‐lived charge‐separated state, RuIII‐ZnP‐C60.−, with a lifetime of 14 μs. The ZnP worked as a visible‐light‐harvesting antenna, while the C60 acted as an excellent electron acceptor. As a consequence, visible‐light‐driven water oxidation by this integrated photosynthetic model compound was achieved in the presence of sacrificial oxidant and redox mediator.  相似文献   

9.
The synthesis and optical absorption of a series of porphyrins, and the photoelectrochemical properties of TiO2 solar cells sensititized with these porphyrins was investigated. The different types of porphyrins studied are designated by numbers: the reference compound 1 (Zinc(II) 5,15-bis(4-carboxylphenyl)porphyrin), porphyrin substituted with one triarylamine unit 2, and porphyrin substituted with two triarylamine units 3. The UV-Vis absorption spectra reveal that the substitutions result in large redshifts in both the Soret band (~ 60 nm) and the Q bands (~ 125 nm), as well as enhancement of optical absorption. The enhancement is even more pronounced in the long-wavelength region of 575–725 nm, where the absorption of porphyrin 3 is eight times that of porphyrin 1. The photoelectrochemical properties of the porphyrins were also studied by constructing porphyrin-sensitized TiO2 solar cells. Under standard AM 1.5 sunlight, the porphyrin 1 cell yields a short-circuit current of ~ 1.26 mA/cm2, an open-circuit voltage of ~ 0.564 V, and a fill factor of ~ 61%. The incident photon-to-current conversion efficiency is ~ 24% for porphyrin 1 and ~ 5–7% for porphyrins 2 and 3 at the Soret peak.  相似文献   

10.
Abstract

A new soluble vic-dioxime, l,4-bis(2-methoxyethyl-2, 3-bis(hydroxyimino)-5, 6-diphenylpiper-azine (LH2) has been synthesized as a mixture of isomers from dicyan di-N-oxide and 1, 2-diphe-nyl-l,2-bis(2′-methoxyethylamino)ethane, 1, which has been prepared through the reduction of the condensation product of benzaldehyde and 2-methoxyethylamine with the aluminium amalgam. LH2 gives N,N-coordinated planar metal complexes with CoII, NiII, CuII and PdII Oxidation of (LH)2Co in the presence of a base such as py or triphenylphoshine leads to octahedral complexes (LH)2Co(B)Cl. The uranyl complex of LH2 has a 1 :1 metal-ligand ratio and a binuclear structure with μ-hydroxo bridges.  相似文献   

11.
The cis-doubly N-confused porphyrin (cis-N2CP, 1) and its Cu(III) and Ag(III) complexes (1–Cu, 1–Ag) form 1-D zigzag infinite chains through hydrogen-bonding interactions between the peripheral core nitrogens (N and NH) in the solid state. Each columnar structure consists of porphyrin rings with the same chirality.  相似文献   

12.
Abstract

A novel dioxime, 1,2 dihydroxyimino-3,7-diaza-9,10-O-benzaloctane (LH2) was prepared by reaction of l,2-0-benzylidene-4-aza-7-aminoheptane and anti-phenylchloroglyoxime in absolute ethanol. Mononuclear complexes with a metal-ligand ratio of 1:2 were prepared with Co(II), Cu(II) and Ni(II). To elucidate the structures of the ligand and complexes, elemental analyses, IR, 1H NMR and 13C NMR spectral data and magnetic susceptibility measurements have been examined.  相似文献   

13.
Freebase 5,10,15,20-tetra(4-pyridyl)porphyrin (TPyP) is able to assemble into crystalline rigid 1D and 2D metallosupramolecular arrrays via exocyclic coordination with tetracoordinate and hexacoordinate metal ions, respectively. In this contribution we report on two coordination polymers of μ 4-bridging freebase TPyP with zinc and manganese halide moieties. The structure of [(ZnBr2)2TPyP] · 6 TCE (2) (TCE = 1,1,2,2-tetrachloroethane) consists of 1D polymeric chains. The topology of [(MnCl2)TPyP] · 6 TCE (3) is the (4,4) square grid type. The crystal structure of the known compound [(HgI2)2TPyP] · 4 TCE (1) was redetermined by X-ray crystallography.  相似文献   

14.
Three novel dyes of JJ1 , JJ2 , and JJ6 featured zinc porphyrin as a basic core structure; N, N‐alkyl‐4‐(prop‐1‐yn‐1‐yl)aniline as an electron donor linked to meso‐10‐position; 4‐(prop‐1‐yn‐1‐yl)benzoic acid as an electron acceptor linked to meso‐20‐position; and 2,6‐bis(dodecyloxy)phenyl or 2,6‐bis(octyloxy)phenyl respectively linked to meso‐5 and meso‐15‐positions of zinc porphyrin have been synthesized and used for dye‐sensitized solar cells. Porphyrin JJ6 featured the shortest alkyl group (─C4H9) on the donor, whereas JJ2 contained the longest alkyl groups (─C12H25), and JJ1 has a medium length of octyl groups. With these new porphyrin sensitizers, we observed that JJ6 has 7.55% power conversion efficiency under simulated one‐sun illumination (AM 1.5 G, 100 mW/cm2) with JSC = 18.64 mA/cm2, VOC = 0.66 V, and fill factor (FF) = 0.61, which was higher than the other two; JJ1 (7.35%) with JSC = 18.83 mA/cm2, VOC = 0.68 V, and FF = 0.60; and JJ2 (6.33%) with JSC = 15.69 mA/cm2, VOC = 0.62 V, and FF = 0.65. The power conversion efficiency of JJ6 and JJ1 were higher than JJ2 , demonstrating that the lengthy alkyl groups on the aniline cause a decrease in efficiency of the devices.  相似文献   

15.
Tunnel recombination of photoseparated charges in frozen vitreous alcoholic solutions of zinc porphyrin (ZnP) and CCl4 has been investigated. Considerable acceleration of the recombination in such systems when exposed to light in the ZnP+ or the CCl4? absorption band region is observed. Possible mechanisms which increase the charge recombination efficiency are considered in detail. The acceleration of the tunnel recombination of ZnP+ and CCl4? under irradiation in the porphyrin absorption band is shown to be due to energy transfer from an excited acceptor to a transferred electron. It is shown that data on the kinetics of photostimulated tunnel reactions can be used to determine the binding energy of a tunnelling electron.  相似文献   

16.
The new compounds A2ZnP2Se6 (A = K, Rb, Cs) were synthesized via molten salt flux syntheses. The crystals feature one‐dimensional 1/[ZnP2Se6]2– chains charge balanced by alkali metal ions between the chains. K2ZnP2Se6 crystallizes in the monoclinic space group P21/c; cell parameters a = 12.537(3) Å, b = 7.2742(14) Å, c = 14.164(3) Å, β = 109.63(3)°, Z = 4, and V = 1216.7(4) Å3. Rb2ZnP2Se6 and Cs2ZnP2Se6 are isotypic, crystallizing in the triclinic space group P$\bar{1}$ . Rb2ZnP2Se6 has cell parameters of a = 7.4944(15) Å, b = 7.6013(15) Å, c = 12.729(3) Å, α = 96.57(3)°, β = 105.52(3)°, γ = 110.54(3)°, Z = 2, and V = 636.6(2) Å3. Cs2ZnP2Se6 has cell parameters of a = 7.6543(6) Å, b = 7.7006(6) Å, c = 12.7373(11) Å, α = 97.007(7)°, β = 104.335(7)°, γ = 109.241(6)°, Z = 2, and V = 669.54(10) Å3.  相似文献   

17.
New MnII/CuII/ZnII complexes [(L1)MnCl2] (1), [(L2)CuCl2]·0.5H2O (2) and [(L2)ZnCl(H2O)][ClO4] (3), containing (2-pyridyl)alkylamine ligands, N-methyl-N,N-bis(2-pyridylmethyl)amine (L1) and methyl[2-(2-pyridyl)ethyl](2-pyridylmethyl)amine (L2), have been prepared and characterized, including X-ray crystallography. The most striking feature of the structures of these complexes is the formation of molecular ladder and lamellar topology through the crystal packing arrangement, determined by both strong O–H···Cl and weak (however, multiple) C–H···Cl hydrogen-bonding interactions, to maintain the neutral/cationic metal-ligand coordination units linked to each other. In 3, additional secondary interactions are observed involving coordinated solvent and the counter-ion. The results presented here demonstrate that (i) the choice of organic ligands to provide flexibility and inherent potential to participate in hydrogen-bonding interactions, (ii) the coordination geometry preferences of metal ions, (iii) the number of metal-bound chloride ion and (iv) the presence of solvent/counter-anion have a great influence on supramolecular network topology.  相似文献   

18.
Three approaches to the synthesis ofN-substituted imino-, hydrazono-, and azino-2,5-cyclohexadienylidene systems based on reactions of 4-methyl-4-trichloromethylcyclohexa-2,5-dienone with aminophenols and hydrazones and condensation of hydrazones ofpara-semiquinoid ketones with carbonyl compounds, including that of the ferrocene series, were realized. The latter reaction, when applied to 3,6-dibromophenanthrene-9, 10-quinone, was accompanied by quantitative aromatizational molecular rearrangement with the elimination of the CCl3 group. Using Rh1 complexes as an example, it was shown that the heteroorganic ligands obtained can be used for the synthesis of mixed-ligand metallocomplexes with triple coordination of the metal atom including simultaneous metal-ligand interactions of the n-, π-, and σ-types. The principle of metal-ligand “cascade” appeared as a result of the generalization of two new phenomena of organometallic sereodynamics, which we have found recently2,3 and have called oxidative and reductive redox-rotation. In the “cascade”, type1 (“metal-ligand-metal”) or type2 (“ligand-metal-ligand”) metallocomplexes, one or several coordinated metal ligand”) metallocomplexes, one or several coordinated metal atoms capable of concertedly and reversibly changing their valence in the course of intramolecular conformational transformation are in positions of mutual conjugation. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 363–367, February, 1997.  相似文献   

19.
Three new Cd(II) complexes incorporating both 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,4-benzenedicarboxylate (bdic2?), [CdCl(bdic)1/2(imb)2]n (1), {[Cd(bdic)(imb)(H2O)]·DMF·2H2O}n (2), and [Cd(bdic)(imb)]·3H2O}n (3), have been prepared and structurally characterized by single crystal X-ray diffraction. Bdic2? anions connect the?Cd-imb-Cd-imb?chains leading to a 2-D structure of 1. Bdic2?(A) and bdic2?(B) anions link the binuclear [Cd2(imb)2(H2O)2] units forming a 2-D structure of 2. Complex 3 features a 2-D structure involving supramolecular “double-layer” motifs. IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis; 13 exhibit good fluorescence in the solid state at room temperature.  相似文献   

20.
在不同反应条件下反应得到了两种1,2,3-三唑衍生物的配合物[Co(H2O)6][Co(L13]2·4H2O(1)和Cu(L222)(HL1=5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid;HL2=1-(4-iodophenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylic acid)。通过X射线单晶衍射和红外光谱确定了晶体结构,同时对配合物12进行了表面作用分析(Hirshfeld surface analysis),在二维指纹图谱中可以清楚的看到配合物中的主要分子间作用。  相似文献   

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