The influence of 1D, meso- and crystal structures on charge transport and recombination in solid-state dye-sensitized solar cells

We have prepared single crystalline SnO2 and ZnO nanowires and polycrystalline TiO2 nanotubes (1D networks) as well as nanoparticle-based films (3D networks) from the same materials to be used as photoanodes for solid-state dye-sensitized solar cells. In general, superior photovoltaic performance can be achieved from devices based on 3-dimensional networks, mostly due to their higher short circuit currents. To further characterize the fabricated devices, the electronic properties of the different networks were measured via the transient photocurrent and photovoltage decay techniques. Nanowire-based devices exhibit extremely high, light independent electron transport rates while recombination dynamics remain unchanged. This indicates, contrary to expectations, a decoupling of transport and recombination dynamics. For typical nanoparticle-based photoanodes, the devices are usually considered electron-limited due to the poor electron transport through nanocrystalline titania networks. In the case of the nanowire-based devices, the system becomes limited by the organic hole transporter used. In the case of polycrystalline TiO2 nanotube-based devices, we observe lower transport rates and higher recombination dynamics than their nanoparticle-based counterparts, suggesting that in order to improve the electron transport properties of solid-state dye-sensitized solar cells, single crystalline structures should be used. These findings should aid future design of photoanodes based on nanowires or porous semiconductors with extended crystallinity to be used in dye-sensitized solar cells. © 2013 The Royal Society of Chemistry.

The synthesis and characterization of novel liquid crystalline, meso-tetra[4-(3,4,5-trialkoxybenzoate)phenyl]porphyrins

Five, novel, meso-tetra[4-(3,4,5-trialkoxybenzoate)phenyl]porphyrins and their metal complexes were synthesized and their molecular structures were confirmed by H-1 NMR, FTIR spectroscopy and elemental analysis. Mesomorphic studies using DSC, polarizing optical microscope and X-ray diffraction revealed that all compounds exhibited thermotropic columnar mesophases over a wide mesophase temperature range and low liquid crystalline-crystal line transition temperature. (c) 2007 Elsevier Ltd. All rights reserved

The synthesis and properties of meso-tetra(4-alkylamidophenyl)porphyrin liquid crystals and their Zn complexes

A series of novel, long-chain-substituted, porphyrin derivatives, meso-tetra (4-alkylamidophenyl) porphyrin ligands and their Zn complexes (alkyl = 8,10,12,14,16,18) were prepared by acylation of the amino groups of 5,10,15,20-tetra(4-aminophenyl)porphyrin by alkyl chloride. Mesomorphism was investigated by DSC, polarized optical microscopy (POM) and X-ray diffraction (XRD). Only ligands containing chains > 12 carbon atoms displayed liquid crystalline behaviour, which exhibited a high phase transition temperature and a broad mesophase temperature span, Zn complexes showed no liquid crystalline behaviour. Cyclic voltammetry, luminescence spectra and surface photovoltage spectroscopy revealed that covalent linking of an alkylamido group to the tetraphenylporphyrin molecule influences, significantly, the properties of the porphyrin macrocycle.

UV-vis spectrophotometric titrations and vibrational spectroscopic characterization of meso-(p-hydroxyphenyl)porphyrins

Sequentially spectrophotometric titrations by sodium hydroxide of meso-tetraphenylporphyrin derivatives bearing one, two, three, or four p-hydroxyl groups result in new types of spectra. The strong new bands appear in the visible region with splitting or broadening of the Soret band and its significant loss of oscillator strength. To understand the molecular origin of these phenomena, the Resonance Raman (RR) and Fourier Transform Infrared (FTIR) experiments are carried out. The results demonstrate that the charges of the deprotonated para-hydroxy substituted meso-tetraphenylporphyrins are localized on the substituents, not delocalized into the pi system of the porphyrin macrocycles and that the ground states of the macrocycles remain essentially unperturbed. Both the related behavior of diprotonated tetrakis(p-(dimethylamino)phenyl) porphyrin and protonated Schiff base porphyrins show that the new bands considered as hyperporphyrin spectra are due to pi(phenoxide anion) --> pi*(porphyrin) transitions, where pi is an orbital on the phenoxide anion substitutent and pi* is a LUMO on the porphyrin.

Sequential deprotonation of meso-(p-hydroxyphenyl)porphyrins in DMF: From hyperporphyrins to sodium porphyrin complexes

Sequential deprotonations of meso-(p-hydroxyphenyl)porphyrins (p-OHTPPH2) in DMF + H2O (V/V = 1:1) mixture have been verified to result in the appearance of hyperporphyrin spectra. However, when the deprotonations of these p-OHTPPH2 are carried out in DMF, the spectral changes differ considerably from those in the mixture mentioned above. At low [OH-], the optical spectra in the visible region are still considered to have characteristics of hyperporphyrin spectra. Further deprotonation at much higher basicity makes the optical spectra form three-banded spectra similar to those in the acidic solution. To clarify the molecular origins of these changes, UV-vis, resonance Raman (RR), proton nuclear magnetic resonance (H-1 NMR) experiments are carried out. Our data give evidence that p-OHTPPH2 in DMF can be further deprotonated of pyrrolic-H by higher concentrated NaOH, due to an aprotic medium like DMF effectively weakening the basicity of the porphyrin relative to that of the NaOH, and coordinates with two sodium ions (except the sodium ions that interact with the peripherial phenoxide anions) to form the sodium complexes of p-OHTPPH2 (Na2P, to lay a strong emphasis on the sodium ions that coordinate with the central nitrogen atom), which can be regarded as the porphyrin anions being perturbed by the sodium cations due to their highly ionic character.

Studies on enzymological properties of antibody elicited by meso-tetra(alpha, alpha, alpha, alpha-O-phenylacetyl benzene)porphyrin

meso-Tetra (alpha, alpha, alpha, alpha-O-phenylacetyl benzene) porphyrin was used as a complete antigen to elicit monoclonal antibody 1F2 through the immunization and cell fusion techniques. McAb 1F2 obtained was demonstrated very pure by HPLC and MALDI/TOFMS. The retention time of McAb 1F2 was 2. 63 min. The subtype of McAb 1F2 was IgG2a. The relative molecular weight was 156 678. 8. When the McAb 1F2-porphyrin was formed, the maximal absorption of the porphyrin soret region had a redshift from 408 to 416 nm and hyperchromical effect, showing that the antigen-antibody combination was rigid and intense, and the abzyme constancy was high. But compared with HRP, the activity of the abzyme was only 4. 687 5 U/mg and 1. 899 % of that of HRP. Its K-m was 20. 29 mmol/L, k(cat) 396. 82 min(-1), k(cat)/K-m. 1. 955 7 X 10(4) L . mol(-1) . min(-1).

抗meso-四(α,α,α,α-O-苯乙酰苯)卟啉抗体的酶学性质研究

利用小分子ｍｅｓｏ－四(α,α,α,α－Ｏ－苯乙酰苯)卟啉作为全抗原免疫小鼠,通过细胞融合等技术制备了单克隆抗体(ＭｃＡｂ)１Ｆ２,利用高效液相色谱(ＨＰＬＣ)、基质辅助激光解吸飞行时间质谱(ＭＡＬＤＩ/ＴＯＦＭＳ)证明纯化得到的单抗是很纯的．ＭｃＡｂ１Ｆ２的保留时间是２．６３ ｍｉｎ,亚型为ＩｇＧ２ａ,相对分子量为１５６ ６７８．８．ＭｃＡｂ １Ｆ２－卟啉复合物形成时,卟啉Ｓｏｒｅｔ带最大吸收峰从４０８ｎｍ红移到４１６ｎｍ,并有增色效应,说明ＭｃＡｂ１Ｆ２－卟啉是刚性且紧密结合．抗体酶稳定性很高,但比活力只有４．６８７ ５ Ｕ/ｍｇ,为天然酶ＨＲＰ的１．８９９%．抗体酶的Ｋｍ＝２０．２９ ｍｍｏｌ/Ｌ,ｋｃａｔ＝３９６．８２ ｍｉｎ－１,ｋｃａｔ/Ｋｍ＝１．９５５ ７×１０４Ｌ·ｍｏｌ－１·ｍｉｎ－１．

Wintertime meso-scale horizontal distribution of large tintinnids in the southern Yellow Sea

Spatial distribution of some large tintinnid species (nominally > 76 mu m) is investigated on samples vertically towed in the southern Yellow Sea in winters of 2001 to 2004. Nine tintinnid species are recorded: Codonellopsis morchella, Stenosemella pacifica, S. steini, Tintinnopsis schotti, T. radix, T. karajacensis, Eutintinnus tenuis, Parafavella sp., Leprotintinnus neriticus, of which C. morchella and T. radix dominated in the warm tongue-shaped zone of the Yellow Sea Warm Current (YSWC), and S. pacifica is the next in abundance. Our study shows that these tintinnids occur repeatedly in certain special distribution patterns.

Meso-scale spatial distribution of large tintinnids in early summer in southern Yellow Sea

The spatial distribution of some large tintinnid species (nominally>76 mu m) was investigated according to samples collected by vertical towing in cruises to the southern Yellow Sea in summer 2000-2002 and 2004. Eight species were identified: Codonellopsis mobilis, Leprotintinnus netritus, Tintinnopsis karajacensis, T. japonica, T. kiaochowensis, T. butschlii, T. radix, and Parafavella sp. With maximum abundance of 158.2 ind/L in June 2004, C mobilis was the dominant species, lasting from May to July 2004. Tintinnid communities were patchy and distributed mainly in shallow waters along the shore.

焦脱镁叶绿酸-a甲酯20-meso-1-位的亲电取代反应

利用焦脱镁叶绿酸-a甲酯与亲电试剂发生的取代反应，在焦脱镁叶绿酸-a甲酯的20-meso-位上分别引进硝基和卤原子，得到了20-meso位取代的焦脱镁叶绿酸衍生物．所合成的新叶绿素-a衍生物均经UV，IR，~1H NMR及元素分析证明其结构．另外，对叶绿素-a卟吩环上的芳香性和相应的化学反应活性也进行了讨论，提出了可能的亲电取代反应机理．

Acid-base and electrochemical properties of manganese meso(ortho- and meta-N-ethylpyridyl)porphyrins: potentiometric, spectrophotometric and spectroelectrochemical study of protolytic and redox equilibria.

The difference in electrostatics and reduction potentials between manganese ortho-tetrakis(N-ethylpyridinium-2-yl)porphyrin (MnTE-2-PyP) and manganese meta-tetrakis(N-ethylpyridinium-3-yl)porphyrin (MnTE-3-PyP) is a challenging topic, particularly because of the high likelihood for their clinical development. Hence, a detailed study of the protolytic and electrochemical speciation of Mn(II-IV)TE-2-PyP and Mn(II-IV)TE-3-PyP in a broad pH range has been performed using the combined spectrophotometric and potentiometric methods. The results reveal that in aqueous solutions within the pH range ∼2-13 the following species exist: (H(2)O)Mn(II)TE-m-PyP(4+), (HO)Mn(II)TE-m-PyP(3+), (H(2)O)(2)Mn(III)TE-m-PyP(5+), (HO)(H(2)O)Mn(III)TE-m-PyP(4+), (O)(H(2)O)Mn(III)TE-m-PyP(3+), (O)(H(2)O)Mn(IV)TE-m-PyP(4+) and (O)(HO)Mn(IV)TE-m-PyP(3+) (m = 2, 3). All the protolytic equilibrium constants that include the accessible species as well as the thermodynamic parameters for each particular protolytic equilibrium have been determined. The corresponding formal reduction potentials related to the reduction of the above species and the thermodynamic parameters describing the accessible reduction couples were calculated as well.

Modelling meso-scale diffusion processes in stochastic fluid bio-membranes

The space–time dynamics of rigid inhomogeneities (inclusions) free to move in a randomly fluctuating fluid bio-membrane is derived and numerically simulated as a function of the membrane shape changes. Both vertically placed (embedded) inclusions and horizontally placed (surface) inclusions are considered. The energetics of the membrane, as a two-dimensional (2D) meso-scale continuum sheet, is described by the Canham–Helfrich Hamiltonian, with the membrane height function treated as a stochastic process. The diffusion parameter of this process acts as the link coupling the membrane shape fluctuations to the kinematics of the inclusions. The latter is described via Ito stochastic differential equation. In addition to stochastic forces, the inclusions also experience membrane-induced deterministic forces. Our aim is to simulate the diffusion-driven aggregation of inclusions and show how the external inclusions arrive at the sites of the embedded inclusions. The model has potential use in such emerging fields as designing a targeted drug delivery system.