Influence of the number of anchor groups on the photophysical properties of coordination compounds as components of dye-sensitized solar cells

The geometry, electronic structure and properties, and composition of frontier molecular orbitals of the Fe^II complex with 4,4´,4´´,4´´´-substituted 2,2´:6´,2´´:6´´,2´´´-quaterpyridine were examined using quantum chemical simulation. This compound was proposed for use as a photoactive component in dye-sensitized solar cells. The regularities were established of the influence of the number of carboxyl groups in the molecular structure on the composition and energy of the frontier orbitals determining the electronic absorption spectra of the studied compounds. The presence of two COOH groups in the structure of the studied complex is the most optimal for use as a sensitizer.     

Photochromic transformations of amphiphilic spiropyran in acetonitrile solutions and at the air/water interface

Russian Chemical Bulletin - The results of a study of the photochromic properties of 1´-hexadecyl-3´,3´-dimethyl-6-nitro-1´,3´-dihydrospiro[chromene-2,2´-indole] (SP)...     

Iron(II) and ruthenium(II) complexes with polypyridine derivatives as sensitizers for DSSC: the structure and spectral properties,as studied by quantum chemistry methods

Density functional calculations of the geometries, electronic structures, and spectral properties of a series of iron(II) and ruthenium(II) complexes with 4,4´,4´,4´´-substituted 2,2´:6´2´´:6´´,2´´´-quaterpyridines were carried out. A high-spin state is characteristic of the iron(II) complexes with Cl^–, NO^–, CNS^–, and I^– as axial ligands while a low-spin state is characteristic of the iron(II) complex with a CN^– axial ligand. Calculations of the complexes with the nitroxide ligand predict intense absorption in a wide wavelength range up to the IR region.     

Synthesis of substituted pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-ones and their sulfinyl and sulfonyl derivatives

A method for the synthesis of previously unknown pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-ones was suggested, which includes a condensation reaction of substituted 3-cyanopyridine-2(1H)-thiones with methyl 2-(chloromethyl)benzoate and subsequent treatment of the condensation products with potassium tert-butoxide. The oxidation of the condensation products to sulfoxides or sulfones and subsequent treatment of these compounds with potassium tert-butoxide led to substituted pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-one 11-oxides or substituted pyrido[3´,2´:4,5]thieno[3,2-c]isoquinolin-5(6H)-one 11,11-dioxides.

     

Synthesis and spectral luminescent properties of 4,4´,4´´,4´´´-tetra(tert-butyl)-5,5´,5´´,5´´´-tetrakis(phenylsulfanyl)phthalocyanines and their sulfo acids

Russian Chemical Bulletin - Magnesium and zinc complexes of 4,4´,4´´,4´´´-tetra(tert-butyl)-5,5´,5´´,5´´´-tetra...     

Conformational analysis of carbonic anhydrase inhibitors using ab initio molecular orbital methods. 1. Rotational isomerism in methane sulfonamide anion, CH3-SO2-NH−

Ab initio calculations have been performed on methane sulfonamide anion. Geometries have been optimized using Hartree-Fock basis sets up to 6-31+G*, and single-point calculations employing those Hartree-Fock geometries have been performed at levels up to MP2/6-311++G**. In addition, geometry optimizations for the 0°, 90°, 150°, and 180° conformers have been carried out at the MP2/6-31G*, MP2/6-31+G*, and MP2/6-311++G** levels. Vibrational frequencies have been calculated using the HF/4-31G*, MP2/6-31G*, and MP2/6-31+G* geometries. All calculations at or above the 4-31G* level agree that H—N—S—C ˜90° is the global minimum. The H—N—S—C = 180° conformer is clearly higher in energy although the relative energy of this conformer varies from 0.36 to 1.03 kcal/mol for the post-HF calculations depending on basis set. The H—N—S—C = 180° conformer appears to be a very shallow local minimum. However, the potential energy surface is quite flat in this region, and the highest-level calculations, including MP2 optimizations and vibrational frequency analysis, are ambiguous on this point. The conformer with an H—N—S—C torsion of 0° is a transition state with a relative energy ˜8 kcal/mol. Received: 3 December 1996 / Accepted: 2 January 1997     

Synthesis and some properties of a polyamide containing trans-2,5-linked tetrahydropyran rings in the main chain

A novel polyamide containing trans-2,5-linked tetrahydropyran rings in the main chain, poly(trans-tetrahydropyran-2,5-diyliminocarbonyl) (trans-polyamide 6 ), was synthesized by the two-stage polycondensation of ethyl or 2,2,2-trifluoroethyl trans-5-aminotetrahydropyran-2-carboxylate ( 5b or 5c ). The polycondensation was carried out first in m-cresol at 180°C. The isolated polymer of a relatively low molecular weight was then allowed to react further in a solid state at different temperatures between 180 and 230°C under vacuum. The trans-polyamide 6 thus obtained was soluble only in protic solvents such as m-cresol, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-isopropanol, and trifluoroacetic acid. The viscosity numbers of 6 were up to 0.46 dL/g in m-cresol at 25°C. DSC and TGA analyses of 6 showed that the thermal decomposition occurred at about 350°C in nitrogen, whereas a rapid weight decrease due to the thermooxidative decomposition started at about 300°C in air. The moisture sorption isotherm was determined on coarsely ground samples of 6 at 25°C and compared with those for the structurally-related polyamides 2 and 4 . © 1993 John Wiley & Sons, Inc.     

Lamivudine phosphoramidates. Unexpected products of a well-known reaction

Russian Chemical Bulletin - A series of phosphoramidate derivatives of β-L-2´,3´-dideoxy-3´-thiacytidine (lamivudine, 3TC), which are the latent forms of 3TC monophosphate, were...     

Increase in dynamic modulus of nylon 6 fiber in repeated heating and cooling cycles under sinusoidal deformation

The repeated heating and cooling cycles under sinusoidal deformation have been investigated on nylon 6 fibers. The fibers zone-drawn twice at high temperatures were used, which have a crystallinity of 52.2% and a birefringence of 59.4×10^?3. The heating and cooling cycle was performed twice at a frequency of 110 Hz over a temperature range from 0°C to 180°C and 190°C. The crystallinity and birefringence of the treated fiber were 51.7% and 60.7×10^?3, respectively, indicating almost no changes in molecular orientation and crystallinity. However, the dynamic modulus, E′, increased steadily over whole temperature range measured. Finally, the E′ value reached 21 GPa at room temperature and 10 GPa ever at 180°C. The elongation of fiber after two cycles was only about 5%. © 1993 John Wiley & Sons, Inc.     

Experimental and DFT studies of ethyl N′-3-(1H-imidazol-1-yl) propylcarbamoyl benzohydrazonate monohydrate

The Imidazole compound, Ethyl N′-3-(1H-imidazol-1-yl) propylcarbamoyl benzohydrazonate monohydrate, has been synthesized and characterized by IR, NMR, electronic spectroscopy, and X-ray single-crystal determination. Molecular geometry from X-ray experiment of the title compound in the ground state has been compared using the density functional method (B3LYP) with 6-31G+(d) basis set. To determine conformational flexibility, molecular energy profile of the title compound was obtained by DFT calculations with respect to two selected degrees of torsional freedom, which were varied from −180° to +180° in steps of 10°. Besides, molecular electrostatic potential (MEP), natural bond orbitals (NBO), frontier molecular orbitals (FMO), and thermodynamic properties were performed at B3LYP/6-31G+(d) level of theory.     

共聚单体乙烯对结晶性无规共聚聚丙烯平台模量的影响

采用齐格勒－纳塔催化剂制备了具有宽分子量分布和超高分子量的无规共聚聚丙烯(UHPPR)。利用平行板流变仪研究了UHPPR在180, 200 and 220℃的粘弹行为,发现UHPPR 180˚C和200˚C的损耗模量G″(ω)曲线,分别在频率为38.10rad/s 和 84.70rad/s处出现最大值峰。从而可以利用特定温度下的损耗模量曲线G″(ω),计算出具有宽分子量分布的结晶性超高分子量无规共聚聚丙烯(UHPPR)的平台模量(G_N⁰),所得UHPPR的平台模量(G_N⁰)在180 ℃和 200 ℃分别为4.51×10⁵ Pa和3.67×10⁵ Pa。这一结果表明,平台模量随乙烯含量的增加而提高,与分子量无关。     

High Acceleration and Improved Diastereoselectivity of Intramolecular Ene-Type Reactions by Diethylaluminum Chloride. Preliminary Communication

The pyrrolidines 2 and 10 were obtained by thermal ene-reactions at +70° and +180° from the (Z)-4-aza-1, 6-diene 1 and from the (E)-4-aza-1, 6-diene 9 in the ratios of 75:25 and 50:50, respectively. On the other hand, these cyclizations proceeded readily in the presence of diethylaluminum chloride at ? 78° and ? 35° giving in high yield the trans-pyrrolidine 2 from 1 with 100% and from 9 with 89% diastereoselectivity.     

Multirotations of (Anilinium)([18]Crown‐6) Supramolecular Cation Structure in Magnetic Salt of [Ni(dmit)2]−

A solid‐state dynamic supramolecular structure consisting of (anilinium)([18]crown‐6) was arranged as the cation in a salt of [Ni(dmit)₂]^? (dmit=2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate). With the ammonium moiety of anilinium located within the cavity of [18]crown‐6, a hydrogen‐bonded supramolecular structure is formed, with an orthogonal arrangement between the π plane of anilinium and the mean O6 plane of [18]crown‐6. In this supramolecular cation, both anilinium and [18]crown‐6 act as dynamic units with different rotational modes in the solid state. The uniform stacks of cations form an antiparallel arrangement, thus producing a layer structure. Sufficient space for the 180° flip‐flop motion of the phenyl ring and the rotation of [18]crown‐6 was observed in the cation layer. Thermally activated 180° flip‐flop motions, with a frequency of 6 MHz at room temperature and an activation energy of 31 kJ mol^?1, were confirmed by temperature‐dependent ²H NMR spectra of ([D₅]anilinium)‐([18]crown‐6)[Ni(dmit)₂]. A double‐minimum potential for the molecular rotation of anilinium, with a barrier of approximately 40 kJ mol^?1, was indicated by ab initio calculations. The wide‐line ¹H NMR spectra indicated a thermally activated rotation of [18]crown‐6 at temperatures above 250 K. Therefore, multiple molecular motions of the 180° flip‐flop motion of the phenyl ring and the rotation of [18]crown‐6 occur simultaneously in the solid state. The temperature‐dependent dielectric constants revealed that the molecular motion of [18]crown‐6, other than the flip‐flop motion, dominates the dielectric response in the measured temperature and frequency range.     

Intramolecular cyclization of 1,3-diamino-2-hydroxypropan-N,N,N´,N´-tetrakis(methylphosphonic acid) upon phosphonomethylation of 1,3-diaminopropan-2-ol

Phosphonomethylation of 1,3-diaminopropan-2-ol affords the mixture of 1,3-diamino-2-hydroxypropan-N,N,N´,N´-tetrakis(methylphosphonic acid) (1) with its cyclic ether, viz., [(6-[bis(phosphonomethyl)amino]methyl-2-hydroxy-2-oxido-1,4,2-oxazaphosphinan-4-yl)methyl]phosphonic acid (2), but not 1, as assumed earlier.

     

Alcoyl-gluco-alcaloides: nouveaux composes isoles de pauridiantha lyalii brem (rubiacees)

La structure destrans fe´ruloyl-6′ ettrans sinapoyl-6′ lyaloside, isole´s des feuilles dePauridiantha Lyalii, ae´te´de´termine´e par de´gradation chimique et par spectroscopie (Masse, RMN¹H et¹³C). Ces compose´s font partie d'un groupe structural caracte´rise´par un enchai?nement alcaloide-monoterpe`ne-ose-acide (C<sub>6</sub>-C<sub>3</sub>), groupe dont un seul repre´sentant semble avoire´te´isole´jusqu'a`pre´sent. Leur fonction dans le ve´ge´tal est discute´e.     

Synthesis and spectral properties of isomers of cobalt tetrakis(dicyanophenoxy)phthalocyaninate

Russian Chemical Bulletin - 4,4´-[1,3-Phenylenebis(oxy)]- and 4,4´-(1,4-phenylenebis(oxy)]diphthalonitriles and the corresponding tetrasubstituted cobalt phthalocyaninates were...     

Synthesis of first representatives of 46-membered P,N,O-containing cyclophanes and their transition metal complexes

Russian Chemical Bulletin - A condensation of phenyl- or l-menthylphosphine with formaldehyde and 4,4´-bis-(4´-aminophenoxy)biphenyl proceeding as a covalent self-assembly gave rise to...     

The preparation and characterization of CdIr(OH)6 and ZnIr(OH)6

CdIr(OH)₆ and ZnIr(OH)₆ were isolated and characterized in the process of synthesizing new ternary oxides of the platinum-group metals by means of thermal decomposition of hydroxide intermediates. Both compounds crystallize with an ordered ReO₃-type structure. CdIr(OH)₆ is tetragonal with a = 7.86 Å and c = 7.91 Å. It is a magnetically dilute insulator. ZnIr(OH)₆ is cubic with a = 7.64 Å. It is an insulator with anomalous magnetic behavior. The cadmium and zinc iridium hexahydroxides decompose at 180 and 170°C, respectively.     

Interpre´tation de la conductivite´electrique de ZrO2 et de HfO2a`haute tempe´rature (1300°C–1600°C)

La mesure du nombre de transport ionique dans HfO₂ et ZrO₂ ae´te´re´alise´e entre 1300°C et 1600°C sous des pressions partielles d'oxyge`ne variant de 1 atma`10^?10 atm. La contribution des porteurs ioniques ete´lectroniques dans la conductivite´totale du mate´riau est discute´e; pour HfO₂, le de´sordre de Schottky rend compte des re´sultats; pour ZrO₂ le ro?le des impurete´s apparait important.     

Structural transition in nickel-doped zinc fluotitanate observed by electron paramagnetic resonance

The EPR spectrum of Ni²⁺ in single crystals of zinc fluotitanate ZnTiF₆·6H₂O has been studied between 4.2 K and room temperature in the frequency range 14.0–16.5 GHz. A structural transition was observed at (180±2) K between a high-temperature trigonal structure and a low temperature orthorhombic structure. Spin hamiltonian parameters are reported above and below the transition.