Novel kappa-type organic metal based on a bis-fused tetrathiafulvalene derivative Y. Misaki, T. Miura, M. Taniguchi, H. Fujiwara, T. Yamabe, T. Mori, H. Mori, S. Tanaka Adv. Mater. 9:9 (1997) p714-716 AMBIENT-PRESSURE, CRYSTAL-STRUCTURE, BEDT-TTF, ELECTRICAL-PROPERTIES, PHYSICAL-PROPERTIES, SUPERCONDUCTOR, DONORS, 2,5-BIS(1',3'-DITHIOL- 2'-YLIDENE)-1,3,4,6-TETRATHIAPENTALENE, DIMENSIONALITY, TEMPERATURE [ @ CAV | @ CHEM: L ] ''electronic structure of insulating salts of the kappa-(bedt- ttf)(2)x family studied by low-temperature specific-heat measurements'' - reply Y. Nakazawa, K. Kanoda Phys. Rev. B - Cond. Matt. 56:2 (1997) p951-952 TRANSITION [ @ CAV | @ CHEM: E | @ SPL: F0.2.6B ] The ac and dc susceptibility data of the identical sample of kappa- (BEDT-TTF)(2)Cu[N(CN)(2)]Cl that we have used for the previous low- temperature specific-heat experiment [Phys. Rev. B 53, R8875 (1996)] is presented in order to reply to the preceding Comment. We observe neither appreciable depression of the magnetic transition temperature nor appearance of superconductive phase due to the grease effect in our experimental configuration, which excludes the interpretation of the specific-heat data speculated by Fortune and Sushko. ''electronic structure of insulating salts of the kappa-(bedt- ttf)(2)x family studied by low-temperature specific-heat measurements'' - comment N.A. Fortune, Y.V. Sushko Phys. Rev. B - Cond. Matt. 56:2 (1997) p949-950 ORGANIC SUPERCONDUCTOR, REENTRANT SUPERCONDUCTIVITY, MAGNETIC-FIELD, PHASE-DIAGRAM, BEDT-TTF, PRESSURE, KAPPA-(BEDT-TTF)2CUCL, TRANSITION, BIS(ETHYLENEDITHIO)TETRATHIAFULVALENE, KAPPA- (ET)2CUCL [ @ CAV | @ CHEM: E | @ SPL: F0.2.6B ] Recently reported specific-heat measurements by Nakazawa and Kanoda between 20 and 50 K show no evidence for an expected antiferromagnetic ordering transition in the quasi-two-dimensional (2D) molecular conductor kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl [Y. Nakazawa and K. Kanoda, Phys. Rev. B 53, R8875 (1996)]. Although the absence of an observable transition was taken as evidence for 2D short-range ordering at elevated temperatures, even a small increase in pressure from the application of the grease used to mount the sample would shift this magnetic transition below 20 K. In their paper, Nakazawa and Kanoda erroneously assume that pressure-induced effects can be ruled out by the magnetic-field independence of the low-temperature specific heat below 3 K. In this Comment, we explain why this assumption is invalid. We conclude that specific-heat measurements in the intermediate temperature range of 3-20 K are needed before the absence of a discernible magnetic and/or pressure- induced phase transitions can be asserted. Zinc-containing chainlike polymer (n), the second example of bridging [s2c=c(cn)(2)] Y.B. Zhu, S.F. Lu, X.Y. Huang, Q.J. Wu, Y.D. Zhang Chinese J. Chem. 15:2 (1997) p188-192 zinc-containing polymer, synthesis, crystal structure The title compound (n) (2), Catena-poly , is the second example of bridging [S2C=C(CN)(2)] (hereafter referred to as i-mnt) for metal- containing polymer. It crystallizes in the non-centrosymmetric space group I-a (alt. Cc, No.9). There are two coordination modes of i-mnt in this compound: mu-eta(1)-eta(1)-i-mnt, bridging two Zn moieties with two S atoms and terminal i-mnt. A characteristic feature of the structure is the infinite -Zn(eta(2)-i-mnt)(eta(1) eta(1)-i-mnt)- Zn(eta(1)-eta(1)-i-mnt)(eta(2)-i-mnt)-wave-like chain. Cs atoms are located between the chains to form three-dimensional network-like packing. An efficient second harmonic generation from the crystal has been observed on the irradiation with the 1064 nm output of a Nd:YAG laser. S center dot center dot center dot s contact-assembled silver(i) complexes of 4,5-ethylenedithio-1,3-dithiole-2-thione having unique supramolecular networks J. Dai, T. Kurodasowa, M. Munakata, M. Maekawa, Y. Suenaga, Y. Ohno J. Chem. Soc. - Dalton Trans. :13 (1997) p2363-2368 1,3-DITHIOLE-2-THIONE-4,5-DITHIOLATE DMIT, CRYSTAL, CHEMISTRY, TETRATHIAFULVALENE, SUPERCONDUCTORS, METALS, RINGS, SALTS [ @ CHEM: L | @ SPL: G0.1.3A ] Two silver(I) complexes of 4,5-ethylenedithio-1,3-dithiole-2-thione (C5H4S5), [ClO4 . CH3CN](2) and [Ag(C5H4S5)CF3SO3](infinity) have been synthesized and characterized crystallographically. They have unique dimeric and two-dimensional structures respectively and are assembled by S ... S contacts. The finding of the shortest S ... S contacts (3.284 and 3.262 Angstrom) in these complexes indicated that the co-ordination linkage in metal complexes containing these types of sulfur donor compounds could be expected to control the intra- or inter-molecular interactions. The co-ordination mode of the C5H4S5 ligand has also been discussed. Toward understanding the vibrational spectra of bedt-ttf, a scaled density functional force field approach R.F. Liu, X.F. Zhou, H. Kasmai Spectr. Acta Part A - Molecular & Biomolecular Spectr. 53:8 (1997) p1241-1256 MOLECULAR GEOMETRIES, RAMAN-SPECTRA, ASSIGNMENT, CRYSTAL, TETRATHIAFULVALENE, SPECTROSCOPY, functional force field, superconductors, vibrational spectra [ @ SPL: F0.1.29A ] Density functional theory B3LYP and ab initio MP2 calculations were carried out to study the structures and vibrational spectra of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) and the related compounds, 1,3-dithiole-2-thione (DTT), tetrathiafulvalene (TTF), and 4,5-ethylenedithio-1,3-dithiole-2-thione (EDT-DTT). It is found that B3LYP functional overestimates C-S bond lengths significantly and underestimates frequencies of modes involving C-S stretching accordingly. The errors in B3LYP force fields are shown to be satisfactorily corrected by scaled quantum mechanical force field procedure. After applying the scale factors derived from DTT, the scaled B3LYP force fields reproduce the observed frequencies of TTF, EDT-DTT, and BEDT-TTF satisfactorily, with a mean deviation between the calculated and observed frequencies of less than 10 cm(-1). On the basis of agreement between the calculated and observed frequencies, isotope shifts, as well as IR and Raman intensities, assignments of the fundamental vibrational modes of these molecules are given in terms of the true molecular symmetries of the equilibrium structures. This study shows that the scaled density functional force field procedure is a powerful approach for understanding the spectral features of large and low symmetry molecules. (C) 1997 Elsevier Science B.V. Rna polymerase i from s-cerevisiae depends on an additional factor to release terminated transcripts from the template H. Tschochne, P. Milkereit Febs Lett. 410:2-3 (1997) p461-466 DNA-BINDING PROTEIN, FACTOR TTF-I, 3' END, INITIATION, ELEMENT, SPACER, SEQUENCES, UPSTREAM, PROMOTER, REB1P, in vitro transcription, RNA polymerase I, transcript release, transcription termination, lac repressor, S-cerevisiae Terminated transcripts were generated at the ends of linearized DNA templates and at DNA-bound lac repressor by in vitro transcription with highly enriched or purified yeast RNA polymerase I (pol I), The release of the synthesized transcripts from the DNA was analyzed using immobilized DNA as template for the transcription reaction. An additional activity distinguishable from pol I was necessary to remove the terminated RNA from the template, Efficiency of transcript release could be improved if a thymidine-rich DNA fragment was located upstream of the transcriptional arrest caused by the DNA- bound lac repressor, The release activity interacted with different forms of polymerases, poll able to initiate on the ribosomal gene promoter and pol I only active in non-specific transcription. (C) 1997 Federation of European Biochemical Societies. Low temperature structure of the alpha prime;-(bedt-ttf)(2)ibr2 organic magnetic semiconductor M. Watanabe, M. Nishikawa, Y. Nogami, K. Oshima, G. Saito J. Korean Phys. Soc. 31:1 (1997) p95-98 BEDT-TTF, CONDUCTORS A low temperature structure analysis for the alpha'-(BEDT-TTF)(2)IBr2 compound has been carried out. The temperatures studied include the regions where anomalous behavior of the conductivity and the susceptibility exist. It has been found that particular terminal ethylene groups of the BEDT-TTF molecules in the unit cell show anomalous temperature-dependent behavior. An anomalous behavior of the unit-cell parameter gamma has been also observed. These are considered to be related with the anomaly of the conductivity around 200 K. No remarkable change in unit-cell parameters has been observed corresponding to the change of the susceptibility around 60 K. It is possible to calculate overlap integrals between the BEDT-TTF molecules by using low-temperature crystal data. They show characteristic changes among three temperatures 300, 120, and 20 K. Organic superconductors - conducting and superconducting characteristics S. Kagoshima J. Korean Phys. Soc. 31:1 (1997) p86-90 TETRAMETHYLTETRASELENAFULVALENE TMTSF, NMR RELAXATION, BEDT-TTF, C-13 NMR, MAGNETORESISTANCE, (TMTSF)2CLO4, STATE, KAPPA- (ET)(2)CUBR, MAGNETOTRANSPORT, ANISOTROPY Normal and superconducting properties of organic superconductors are reviewed in the light of the characteristic properties of molecular materials. Examples are shown of artificial design and control of constituent molecules in BEDT-TTF- and TMTSF-based superconductors. Low-dimensional electronic properties are discussed in relation to studies of the topology of the Fermi surface in organic conductors and superconductors. The roles of the electron-electron Coulomb correlation are discussed in the light of symmetry and possible mechanisms of superconductivity. Unconventional behavior of the scattering times in high-t-c cuprates I. Terasaki, Y. Sato, S. Tajima J. Korean Phys. Soc. 31:1 (1997) p23-26 QUASI-PARTICLE SCATTERING, YBA2CU3O7-DELTA, SUPERCONDUCTIVITY, LA2- XSRXCUO4, LIMIT, STATE We have measured the anisotropic charge dynamics in the 90-K phase of YBa2Cu3Oy, and have found that the out-of-plane scattering time is more than five times shorter than the in-plane scattering time. Another anomaly is the rapid enhancement of the in-plane scattering time below T-c. Our magneto-thermopower measurement has revealed that the enhancement also occurs in the mixed state. These two features are never observed in other layered superconductors, such as organic BEDT salts or Sr2RuO4; thus, they can be direct evidence for the non- Fermi-liquid behavior of high-T-c cuprates. Synthesis and some properties of bis- and tetrakis(triphenylstannyl)tetrathiafulvalenes and tetraiodotetrathiafulvalene M. Sato, M. Sensui J. Organometallic Chem. 538:1-2 (1997) p1-8 CROSS-COUPLING REACTION, TETRATHIAFULVALENES TTF, CRYSTAL-STRUCTURE, ELECTRON-DONOR, GENERAL-METHOD, PALLADIUM, SUBSTITUENTS, COMPLEXES, Sn, X-ray diffraction, charge-transfer complex Bis- and tetrakis(triphenylstannyl)tetrathiafulvalenes were prepared from the corresponding lithio-derivatives and chlorotriphenyltin, and their structures were determined by X-ray analysis. Their absorption maxima in the electronic spectrum showed a bathochromic shift. Their redox potentials shifted only a little to a lower region. The charge- transfer complex of the tetra-substituted derivative with TCNQ was isolated. Bis(trimethylstannyl)tetrathiafulvalene did not react with (eta-Cp)(CO)(2)FeI and the reaction with (COD)PtCl2, followed by addition of tributylphosphine, gave a complex mixture, from which (C2H2S2)Pt(PBu3)(2) was isolated in a low yield. The structure was confirmed by X-ray diffraction. A convenient preparation of tetrathiafulvalene and tetraiodotetrathiafulvalene is also reported. (C) 1997 Elsevier Science S.A. Synthesis and electrochemistry of new tetrathiafulvalene (ttf) dendrimers: x-ray crystal structure of a tetrafunctionalised ttf core unit C.S. Wang, M.R. Bryce, A.S. Batsanov, L.M. Goldenberg, J.A.K. Howard J. Mater. Chem. 7:7 (1997) p1189-1197 CATION-RADICAL SALTS, DENDRITIC MACROMOLECULES, OLIGOMERIC TETRATHIAFULVALENES, CESIUM TETRATHIAFULVALENE, CYCLIC VOLTAMMETRY, ORGANIC-CHEMISTRY, BUILDING-BLOCKS, MOLECULAR TREES, THIN-LAYER, DERIVATIVES [ @ CHEM: A ] A new synthetic approach to tetrathiafulvalene (TTF) dendrimers is reported. Tetrakis (4-chloromethylbenzylthio)tetrathiafulvalene 7 is a functionalised core unit which reacts with four equivalents of the thiolate ion generated from compound 16 to afford the trisdeca-TTF derivative 3. Compound 3 is a shelf-stable solid which has been characterised by elemental analysis? MALDI-TOF mass spectrometry, H-1 NMR spectroscopy and solution electrochemistry. Thin layer cyclic voltammetry studies on Fentakis-TTF and trisdeca-TTF derivatives 11 and 3 in dichloromethane solution in the presence of 2,3- dichloronaphthoquinone as an internal reference, show that all the TTF units undergo two single-electron oxidations. The single crystal X-ray structure of compound 7 is reported: the molecules have crystallographic C-i symmetry and form chair-like stacks parallel to the crystallographic y axis. A conducting salt-based amperometric biosensor for measurement of extracellular lactate accumulation in ischemic myocardium S.A.M. Marzouk, V.V. Cosofret, R.P. Buck, H. Yang, W.E. Cascio, S.S.M. Hassan Anal. Chem. 69:14 (1997) p2646-2652 DIRECT ELECTRICAL COMMUNICATION, CHEMICALLY MODIFIED ENZYMES, GLUCOSE-OXIDASE, TETRACYANOQUINODIMETHANE ELECTRODE, METAL-ELECTRODES, XANTHINE-OXIDASE, CARBON-PASTE, TETRATHIAFULVALENE, SENSOR, OXIDATION In this paper, fabrication, characterization, and physiological application of a miniaturized amperometric lactate biosensor are described. The sensor is based on cross-linked lactate oxidase and tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) charge transfer complex. The sensor was developed for continuous quantitative measurement of the lactate accumulation in ischemic myocardium under severe depletion of oxygen. The sensor was evaluated in vitro at an applied potential of 0.15 V vs Ag/AgCl; it proved to combine all the performance characteristics desired for the present application, such as proper response in absence of oxygen, good operational stability, good accuracy and precision (103.5 +/- 1.2%), adequate response time (t(95%) = 80 s), and wide linear dynamic range up to 27 mM (r = 0.9998) in N-2-saturated solutions and at 37 degrees C. The prepared sensors (n = 12) showed sensitivity of 380 +/- 90 nA/mM, and a background current of 240 +/- 50 nA. The lower limit of detection is 0.4 +/- 0.15 mM with a S/N ratio equal to 3. Results obtained for direct lactate monitoring in ischemic rabbit papillary muscle under no-flow conditions and PO2 <6 mm Hg are presented. 1,3-bis(1,3-dithiol-2-ylidene)-1,3-dihydrobenzo[c]heterophenes. new fused heterocycle extended donors and their conducting tcnq-complexes K. Takahashi, T. Ise Heterocycles 45:6 (1997) p1051-1054 BEDT-TTF, ANALOGS A series of new fused-heterocycle-extended donors have been synthesized by convenient and short-step reactions. Of these benzo[c]furoquinonoid-extended one has the lowest oxidation potential. TCNQ complexes of these donors exhibit fairly high conductivities even when measured on compressed pellets. Ab initio estimate of hubbard model parameters: a simple procedure applied to bedt-ttf salts A. Fortunelli, A. Painelli Phys. Rev. B - Cond. Matt. 55:24 (1997) p16088-16095 PI-ELECTRON METHODS, ORBITAL RELAXATION, ONE DIMENSION, SOLID-STATE, SUPERCONDUCTIVITY, COMPUTATION, TRANSFERABILITY, DEPENDENCE, (TMTSF)2X, MOLECULE [ @ CAV | @ CHEM: E | @ SPL: F0.2.6B ] We describe a simple procedure to extract the parameters of the one- band Hubbard model from a set of ab initio calculations on a dimeric unit. The method applies to narrow band solids with negligible orbital relaxation. In this paper we consider a specific system, kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Br, but the proposed procedure is of general applicability. From a detailed discussion of the ab initio data, we extract a few general criteria of wide applicability about the relative magnitude of the empirical model parameters. We prove that the Hubbard model, including both on-site and inter-site electron-electron interactions, is a reliable model for systems with negligible orbital relaxation, apart from particular geometrical arrangements. The hopping parameter (t), as well as the intersite electronic repulsion (V), are barely affected by the chemical environment. On the contrary, the on-site energy and the on-site repulsion (the Hubbard h and U) show an appreciable dependence on the chemical environment, through a dependence of the frontier and core energies on the surrounding potential. Quantum galvanomagnetic effects in the organic metal alpha-(bedt- ttf)(2)tlhg(scn)(4) N. Harrison, M.M. Honold, M.V. Kartsovnik, J. Singleton, S.T. Hannahs, D.G. Rickel, N.D. Kushch Phys. Rev. B - Cond. Matt. 55:24 (1997) p16005-16008 CONDUCTOR ALPHA-(BEDT-TTF)2KHG(SCN)4, MAGNETIC-FIELDS, BEDT-TTF, BIS(ETHYLENEDITHIO)TETRATHIAFULVALENE, (ET)2TLHG(SCN)4, CRYSTAL, SALT [ @ CAV | @ CHEM: E | @ SPL: F0.2.6B ] The transverse magnetoresistance and Hall effect of the organic metal alpha-(BEDT-TTF)(2)TlHg(SCN)(4) have been studied in static magnetic fields of up to 33 T applied perpendicular to the highly conducting planes. The Hall resistivity is found to exhibit strong oscillations caused by the coexistance of quasi-one-dimensional and quasi-two- dimensional states in the electronic system. In higher quality crystals, plateaulike features appear at magnetic fields above similar to 30 T, which are consistent with recent claims of the quantum Hall effect in this material. Semifluorinated ttf derivatives in langmuir-blodgett films C. Mingotaud, B. Agricole, T. Nozdryn, J. Cousseau, A. Gorgues, P. Delhaes Thin Solid Films 300:1-2 (1997) p228-233 MULTILAYERS, MONOLAYERS, SALTS, conductivity, infrared spectroscopy, Langmuir-Blodgett films, surface pressure [ @ CAV | @ SPL: F0.43.2 ] New semifluorinated tetrathiafulvalene (TTF) derivatives were prepared and used in Langmuir and Langmuir-Blodgett (LB) films. Transfer onto a solid substrate of such pure monolayers can be easily achieved leading to organized LB films in which the fluorinated chains are tilted with respect to the normal of the substrate as demonstrated by infrared and X-ray experiments. Doping of such films by iodine does not induce change in the layer spacing on the contrary to already published studies concerning alkyl derivatives of TTF. Such structural stability and values of the layer thickness suggest some interdigitation between TTF groups within the LB film. Depending on the exact chemical structure of the TTF moiety, the iodination is stabilized or not. When the doped film is stabilized in a mixed valency state, conductivity of approx. 10(-2) S cm(-1) was measured at room temperature. (C) 1997 Elsevier Science S.A. The influence of the electrodeposition parameters on the morphology of organo-transition metal complexes for thin film gas sensor applications J.R. Bates, P. Kathirgamanathan, R.W. Miles Thin Solid Films 299:1-2 (1997) p18-24 CONDUCTIVITY, DMIT, gas sensors, electrodeposition, organo-transition metal complexes [ @ CAV | @ SPL: F0.43.2 ] This paper describes the electrodeposition of tetrabutylammonium bis(1,3-dithiol-2-thione-4,5-dithiolate) nickelate (Bu4NNi(dmit)(2)) onto platinum, gold interdigitated and fluoride-doped tin oxide electrodes. The effects of adding pyrrole, thiophene, 3- methylthiophene and furan to the deposition solution on the film morphology were investigated. The bulk conductivity of the deposited films was found to be 4 x 10(-2) S cm(-1) irrespective of the heterocycle added. Cyclic voltammetry was carried out using the three electrodes: the gold and platinum electrodes showed similar electrochemical behaviour, with the peaks assigned to the redox properties of the metal-dmit; the SnO2 electrode did not yield any distinct peaks. It is suggested that this was because the rate of electron transfer to the SnO2 electrode was the rate-limiting step rather than the rate of diffusion to the electrode surface as in the case of the platinum and gold electrodes. The films deposited onto the interdigitated gold electrodes were exposed to sulphur dioxide and changes in the film resistance were monitored. Films deposited in dichloromethane had a much lower surface area than those deposited from nitrobenzene, and the magnitude of the change in resistance on exposure to sulphur dioxide was a factor of four tower than for the films deposited in nitrobenzene. Studies were also carried out on copper and cobalt dmit analogues; the copper-dmit behaved in a similar manner to the nickel-dmit, although the films were of very low conductivity,whereas the cobalt-dmit showed no reversible redox behaviour. (C) 1997 Elsevier Science S.A. Cyclotron resonance in the organic conductor (bedo-ttf)(2)reo4(h2o) in the millimeter wavelength band S.V. Demishev, A.V. Semeno, N.E. Sluchanko, N.A. Samarin, I.B. Voskoboinikov, M.V. Kartsovnik, A.E. Kovalev, N.D. Kushch J. Experimental & Theoretical Phys. 84:3 (1997) p540-544 ELECTRON DYNAMICS Resonant microwave absorption in a (BEDO-TTF)(2)ReO4(H2O) organic conductor single crystal at a temperature of 1.9 K, a magnetic field of up to 70 kOe, and in the frequency band between 30 and 120 GHz has been studied. A spectral component due to the cyclotron resonance (CR) of two-dimensional charge carriers has been identified for nu greater than or equal to 80 GHz and H greater than or equal to 10 kOe. The effective mass m(omega) increases with the frequency from m approximate to 0.8 m(0) at nu = 80 GHz to m approximate to 0.95 m(0) at nu = 120 GHz. Measurements of the CR line position and FWHM as functions of frequency yield an independently determined imaginary part of the memory function M(omega), which controls the dynamic magnetoconductivity, and the relaxation time tau(nu = 100 GHz) approximate to 2.9 x 10(-11) s, which is more than thirty times the value of this parameter in the low-frequency limit tau(nu --> 0). The anomalous behavior of the CR line position and FWHM is caused try the dispersion of both real and imaginary parts of M(omega), which are probably due to strong Fermi-liquid effects. (C) 1997 American Institute of Physics. Mcgr: an inverse method for deriving the pair correlation function from the structure factor L. Pusztai, R.L. Mcgreevy Phys. B 234: (1997) p357-358 computer modelling, disordered materials, diffraction, diffuse scattering [ @ CAV | @ SPL: F0.42.1B ] MCGR is a Monte-Carlo program for determining the pair correlation function (pcf), G(r), of a material from the total structure factor (tsf), F(Q), by an inverse method. Some of the latest developments are reviewed here: (a) coordination constraints, (b) Gaussian smoothing, (c) refinement of a quadratic background and (d) pcf's for crystalline powders. Experience suggests that MCGR can be used as a sensitive test of data quality, allowing the rapid assessment of instrument performance. Studies on new tetrathiafulvalene (ttf) donors. synthesis and characterization H.Q. Li, G.Z. Tan, Y.X. Song, X.D. Yu, Z.Q. Yao Synth. Met. 87:2 (1997) p151-156 RAY CRYSTAL-STRUCTURES, ELECTROPHILES, DERIVATIVES, tetrathiafulvalene, donor, synthesis, electronic absorption spectrum [ @ CAV ] A series of new tetrathiafulvalene (TTF) derivatives and related compounds with halogen substituents were synthesized. The compounds were characterized by elemental analysis, H-1 NMR spectra, electron ionization (EI) or negative-ion fast atom bombardment mass spectra (FAB-MS) analysis, Fourier transform infrared (FT-IR) spectra and UV- Vis spectral analysis. The electronic absorption spectral studies on the new TTF derivatives revealed that the energy differences between the pi-orbitals of the new TTF derivatives were smaller than that between BEDT-TTF (bis(ethylenedithio)-tetrathiafulvalene). Structures and properties of medtdm salts Y. Misaki, M. Taniguchi, T. Miura, H. Fujiwara, T. Yamabe, T. Kawamoto, T. Mori Adv. Mater. 9:8 (1997) p633-635 AMBIENT-PRESSURE SUPERCONDUCTIVITY, ELECTRICAL-PROPERTIES, CRYSTAL- STRUCTURE, 1,3-DITHIOL-2-YLIDENE MOIETIES, ORGANIC SUPERCONDUCTORS, BAND STRUCTURES, TTF, TETRATHIAFULVALENE, DERIVATIVES, METALS [ @ CAV | @ CHEM: L ] Pt resistor thermometry and pressure calibration in a clamped pressure cell with the medium, daphne 7373 K. Murata, H. Yoshino, H.O. Yadav, Y. Honda, N. Shirakawa Rev. Sci. Instruments 68:6 (1997) p2490-2493 SUPERCONDUCTIVITY, BETA-(BEDT-TTF)2I3 [ @ CAV ] Calibration of a Pt resistance thermometer (Netsushin) in magnetic fields and under pressure in the range of 1.5-300 K and below 1.5 GPa is presented. With the pressure medium, olefin olygomers, Daphne 7373, the pressure is continuous at its solidification and the pressure drop from 300 to 4.2 K by 0.15-0.17 GPa is constant, irrespective of the initial clamped pressure at 300 K. The applicability of the thermometer and the medium for precise study in field and pressure at low temperature is discussed. (C) 1997 American Institute of Physics. Efficient photoinduced electron transfer between c-60 and tetrathiafulvalenes studied by nanosecond laser photolysis M.M. Alam, A. Watanabe, O. Ito J. Photochemistry & Photobiology A - Chem. 104:1-3 (1997) p59-64 FLASH-PHOTOLYSIS, CHARGE-TRANSFER, PULSE-RADIOLYSIS, TRANSIENT ABSORPTION, C60, FULLERENES, TRIPLET, DERIVATIVES, COMPLEXES, SPECTRA, C-60, electron transfer, laser photolysis, tetrathiafulvalene Photoinduced electron transfer between C-60 and tetrathiafulvalene (TTF) or bis(ethylenedithio) tetrathiafulvalene (BEDT-TTF) in polar and non-polar solvents and their mixtures was investigated by nanosecond laser photolysis/transient absorption spectroscopy in the visible and near-IR regions. The transient absorption bands of the C- 60 triplet (C-T(60)*) observed in polar solvents decay on addition TTF (or BEDT-TTF), accompanied by the appearance of the transient absorption bands of C-60(.-). The yields of C-60(.-) are decreased on addition of O-2, revealing that about 10% of C-60(.-) is produced via the singlet state at donor concentrations of less than 5 x 10(-3) M. In benzene, the quenching of C-T(60)* without the appearance of C- 60(.-) within the nanosecond laser pulse is attributed to collisional quenching. The quantum efficiencies of C-60(.-) formation via C- T(60)*, which were evaluated from the initial [C-T(60)*] and maximal [C-60(.-)] values, vary with the donor ability and solvent polarity. The forward electron transfer rate constants were evaluated from the decay rates of C-T(60)* (or the rise rates of C-60(.-)) after multiplying by the quantum efficiencies. The back electron transfer rates are slowed down in polar solvents. (C) 1997 Elsevier Science S.A. Resonance raman study of solvent dynamics in electron transfer .2. betaine-30 in ch3oh and cd3od Y.P. Zong, J.L. Mchale J. Chem. Phys. 107:8 (1997) p2920-2929 FEMTOSECOND SOLVATION DYNAMICS, HYDROGEN-BONDING LIQUIDS, CHARGE- TRANSFER COMPLEX, FRANCK-CONDON BARRIER, REORGANIZATION ENERGIES, DIELECTRIC-RELAXATION, COMPUTER-SIMULATIONS, MOLECULAR-DYNAMICS, PRERESONANCE RAMAN, TRANSFER KINETICS [ @ CAV | @ CHEM: A | @ SPL: G1.2.5 ] Raman excitation profiles for twelve vibrational modes of the solvatochromic dye betaine-30 have been measured in CH3OH and CD,OD solutions at wavelengths that span the S-0-->S-1 charge transfer transition. Though the absorption spectra of the dye are the same in the protonated and deuterated forms of the solvent, Raman cross- sections for all modes were found to be generally lower in the CH3OH solution than in CD3OD. The time-dependent theory of Heller was applied to model the absorption and Raman profiles, and both mono-and bi-exponential solvent relaxation were considered in order to account for solvent induced electronic dephasing. The two models lead to different physical pictures for the relevant solvent dynamics, but in either case the amplitude of solvent dephasing is reduced in deuterated compared to protonated methanol. The effect is interpreted in terms of stronger solvent-solute and solvent-solvent hydrogen bonding in deuterated methanol solution. Comparing to previous results for betaine-30 Raman cross-sections in acetonitrile [Y. Zong and J. L. McHale, J. Chem. Phys. 106, 4963 (1997)], it is concluded that slower solvent dynamics and perturbations to the electronic structure of betaine-30 lend to larger Raman intensities in methanol. The data suggest that solvent dynamics depend strongly on the electronic state of betaine-30. (C) 1997 American Institute of Physics. A study of the nonlinear optical transmittance in a variety of tcnq- based organometallic colloidal suspensions P.R. Schuster, C.A. Viands, R.S. Potember, M.G. Schmitt J. Nonlinear Optic. Phys. & Mater. 6:2 (1997) p141-150 TETRACYANOQUINODIMETHANE TCNQ, KERR MEDIUM, THIN-FILMS, METAL, TRANSITIONS, DEPENDENCE, GLASSES, SALTS Optical limiting in a series of novel aqueous colloidal suspensions is investigated. The suspensions consist of an organometallic charge- transfer complex based on the organic acceptor 7,7,8,8- tetracyanoquinodimethane (TCNQ). We report on the synthesis of the organometallic complexes and their effectiveness at limiting nanosecond pulses at 532 nm. It is shown that some of the charge- transfer systems can effectively attenuate pulses at rates up to 10 Hz while other systems require continuous agitation in order to most efficiently limit the laser radiation. Finally we discuss the reversible field-induced phase transition that produces the observed nonlinear absorption. Spectrophotometric study of the charge transfer complexes of some pharmaceutical butyrophenones H.F. Askal Talanta 44:10 (1997) p1749-1755 PERFORMANCE LIQUID-CHROMATOGRAPHY, DROPERIDOL, charge transfer complexes, droperidol, haloperidol, spectrophotometry The molecular interactions between haloperidol and droperidol as electron donors and each of iodine; 7,7,8,8-tetracyanoquinodimethane (TCNQ); 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ); tetracyanoethylene (TCNE); 2,4,7-trinitro-9-fluorenon (TNF); and 2-3- 5-6-tetrabromo-1,4-benzoquinone (Bromanil) as accepters have been investigated spectrophotometrically. Different variables affecting the reaction were studies and optimized. Beer's law was obeyed in a concentration limit of 2.5-2500 mu g ml(-1) for the studied drugs with various accepters used. Electron affinities (E-A) of the accepters were found to correlate with both the time required for maximum colour formation and the molar absorptivities of haloperidol and droperidol. A Job's plot of the absorbance versus the molar ratio of the drugs to iodine indicated 1:1 ratio. The proposed methods were found to be rapid and sensitive and may be applied for estimation of named drugs in pharmaceutical dosage forms without interferences from the common additives encountered. Percentage recoveries ranged from 99.1-102.2%. (C) 1997 Elsevier Science B.V. Structural characterization of mixed-stack charge transfer films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane and 5,10-dimethyl-5,10- dihydrophenazine prepared by the langmuir-blodgett technique and donor doping .3. thickness dependence of thermal behavior investigated by ultraviolet-visible-near-infrared and infrared spectroscopies and x-ray diffraction Y. Wang, K. Nichogi, K. Iriyama, Y. Ozaki J. Phys. Chem. B 101:33 (1997) p6379-6383 REFLECTION-ABSORPTION-SPECTROSCOPY, STEARIC-ACID Thermal behavior of mixed-stack charge transfer (CT) films prepared by 5,10-dimethyl-5,10-dihydrophenazine ((Me)(2)P) doping of Langmuir- Blodgett (LB) films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (octadecyl-TCNQ) has been investigated by using X-ray diffraction and ultraviolet-visible-near-infrared (UV-vis-NIR) and infrared (IR) spectroscopies. Temperature-dependent changes in the UV-vis-NIR and IR spectra reveal that donors (D, (Me)(2)P) dedope from the CT complex, resulting in a restoration of accepters (A, octadecyl-TCNQ) to their neutral state in the temperature range 70-90 degrees C. The dedope temperature was determined to be 80, 84, 86, and 88 degrees C for the 1-, 3-, 7-, and 11-layer CT films, respectively, by monitoring an a, C=N stretching band of the TCNQ chromophore in the temperature-dependent IR spectra. From room temperature to 60 degrees C, the molecular arrangement and orientation of D and A in the well- ordered multilayered CT complex seem to be thermally stable because the X-ray diffraction pattern and UV-vis-NIR and IR spectra are nearly unchanged. The dedoping begins in the temperature range 60-70 degrees C, but it proceeds rather slowly for the multilayered CT films. Dramatic structural changes take place in the region of 70-90 degrees C, where the X-ray diffraction pattern and characteristic absorption bands of the CT complex in the UV-vis-NIR and IR spectra disappear. The thickness-dependent thermal behavior may be attributed to the longitudinal interactions between the sheetlike multilayered microcrystals as well as to the interaction between the first layer and a CaF2 substrate. Structural characterization of mixed-stack charge transfer films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane and 5,10-dimethyl-5,10- dihydrophenazine prepared by the langmuir-blodgett technique and donor doping .2. morphology and annealing effects investigated by atomic force microscopy and ultraviolet-visible-near-infrared, and infrared spectroscopies Y. Wang, K. Nichogi, K. Iriyama, Y. Ozaki J. Phys. Chem. B 101:33 (1997) p6372-6378 TRANSITION, IONICITY Morphology and annealing effects of mixed-stack charge transfer (CT) complex films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (octadecyl-TCNQ) doped by 5,10-dimethyl-5,10-dihydrophenazine ((Me)(2)P) have been investigated by atomic force microscopy (AFM) and ultraviolet-visible-near-infrared (UV-vis-NIR) and infrared (IR) spectroscopies. The AFM measurements scanned at room temperature show that the 11-layer CT film consists of layered platelet microcrystal domains with a layer distance of 3.3 nm, which is in good agreement with the distance obtained by an X-ray diffraction experiment. It is likely that each layer in the CT film has a bimolecular layer structure as in the case of Langmuir-Blodgett (LB) films of neutral octadecyl-TCNQ. A two-dimensionally resolved molecular arrangement of octadecyl-TCNQ and (Me)(2)P is observed inside the domains by a high- resolution AFM image. The inter-and intrastack periods, which are across and along the CT stacks, are 0.96 and 0.83 nm, respectively, with an intersect angle of 59 degrees. A cyclic thermal treatment on the CT film up to 70 degrees C, which is below the dedope temperature, does not change its morphology, i.e., the molecular arrangement and layered structure in the microcrystal domains are nearly unchanged. However, when the CT film is heated above the dedope temperature, the layered structure vanishes completely and the molecular arrangement becomes similar to that in the LB film of neutral octadecyl-TCNQ. The UV-vis-NIR and IR spectra of the annealed CT films confirm the results obtained by AFM. Structural characterization of mixed-stack charge transfer films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane and 5,10-dimethyl-5,10- dihydrophenazine prepared by the langmuir-blodgett technique and donor doping .1. molecular orientation and structure investigated by ultraviolet-visible-near-infrared and infrared spectroscopies and x- ray diffraction Y. Wang, K. Nichogi, K. Iriyama, Y. Ozaki J. Phys. Chem. B 101:33 (1997) p6367-6371 IONIC PHASE-TRANSITION, TETRATHIAFULVALENE-PARA-CHLORANIL, TCNQ, SALTS Molecular orientation and structure in mixed-stack charge transfer (CT) films of 2-octadecyl-7,7,8,8-tetracyanoquinodimethane (octadecyl-TCNQ) doped by 5,10-dimethyl-5,10-dihydrophenazine ((Me)(2)P) have been investigated by using ultraviolet-visible-near- infrared (UV-vis-NIR) and infrared (IR) spectroscopies and X-ray diffraction. The degree of charge transfer (rho) was determined to be 0.5 by a shift of a b(1u) C=N stretching band of the TCNQ chromophore, suggesting that the complex is close to the neutral- ionic boundary. An X-ray diffraction pattern indicates that the CT films consist of a highly ordered multilayered structure in which donor ((Me)(2)P) and acceptor (octadecyl-TCNQ) molecules are periodically arranged. The d value was calculated to be 3.3 nm, implying that each layer of the CT films comprises bimolecular layers. Comparison of IR intensities of b(1u), b(2u), and a(g) C=N stretching bands of the acceptor (A) and a totally symmetric band at 1255 cm(-1) of the donor (D) between the transmission and reflectance absorption (RA) IR spectra indicates that the chromophores of D and A are almost perpendicular to the substrate surface with their long molecular axes being nearly parallel to the surface normal in the one-layer mixed-stack CT films. The hydrocarbon chain of octadecyl- TCNQ was evaluated to lie on the substrate. In the multilayer CT films the D and A chromophoric planes seem to be slightly tilted with respect to the substrate surface. Nexafs investigations on highly-ordered ultrathin films of dme-dcnqi on single crystal surfaces M. Bassler, R. Fink, C. Buchberger, D. Gador, C. Heske, J. Muller, P. Vaterlein, J.U. vonschutz, E. Umbach J. De Phys. Iv 7:C2 Pt1 (1997) p531-532 [ @ CAV | @ SPL: F0.4.3C ] DMe-DCNQI forms highly-ordered ultrathin films on various single crystal surfaces. NEXAFS reveals flat lying molecules for all investigated film thicknesses (up to 40 layers) on nearly all substrates under investigation (Ag(111), Ag(100), Cu(100), Cu(111)). The C1s and N1s NEXAFS spectra of these condensed layers show several very sharp resonances. The comparison with the quinoide molecules TCNQ and DMe-BQ shows similarities, but the electronic structure is too complicated to be interpreted in terms of a building block scheme. NEXAFS data of related charge transfer salts consist of fewer and much broader resonances in accordance with the more delocalized electronic structure of the 'quasimetallic' salts. Computer simulation of water clusters containing an h2o-o-2 charge- transfer complex D.H.V. Dossantos, S.J. Vaughn, E.V. Akhmatskaya, M.A. Vincent, A.J. Masters J. Chem. Soc. - Faraday Trans. 93:16 (1997) p2781-2785 MOLECULAR-DYNAMICS, OXYGEN [ @ CHEM: D | @ SPL: G0.1.3D ] A proposed mechanism for the photonucleation of water vapour in the presence of oxygen involves the initial formation of a charge- transfer (CT) complex of molecular oxygen and water, H2O+O2-. The large dipole of this complex then attracts the surrounding polar water molecules, thereby forming a cluster. To investigate the properties of such a cluster, we have carried out computer simulations at 300 K using two different water models. For both models, we found that the complex resided preferentially at the surface of the cluster despite its large dipole moment. This preference was in accord with the results of ab initio calculations carried out on a small cluster. The internal energy difference between a cluster of n water molecules and a cluster of (n - 1) water molecules and one complex was of the order of 10-20 kJ mol(-1), the precise value depending on the cluster size. This energetic stabilisation reflects the fact that the CT complex can make three hydrogen bonds in contrast to the two made by a water molecule. Photoinduced electron-transfer reaction of azo compounds japanese A. Kitamura, N. Miyagawa, T. Karatsu J. Synth. Organic Chem. Jap. 55:8 (1997) p678-685 CATION RADICAL SALTS, OXIDATIVE DECOMPOSITION, BICYCLIC AZOALKANES, DEFICIENT DIENES, CHARGE-TRANSFER, REARRANGEMENT, PHOTOCHEMISTRY, 2,3-DIAZABICYCLO<2.2.2>OCT-2-ENE, GENERATION, 1,4-DIPHENYL-2,3- DIAZABICYCLO<2.2.2>OCT-2-ENE, azoalkane, azo compound, photoinduced electron transfer, radical cation, ion radical, charge-transfer complex, back electron transfer Recently, photoinduced electron transfer (PET) reactions have been focused on the behavior of radical-ion species. Here, we review the PET reactions of azo compounds, especially azoalkanes. Ground state interactions between azoalkanes and cationic salts have been investigated. On the basis of these results, studies of CT band excitation and PET reactions are developed. There are two types of the PET reactions. One is the electron transfer from the excited molecules of azoalkanes to the ground stale electron acceptor molecules, and the other is the electron transfer from the ground stale molecules of azoalkanes to the excited electron acceptor molecules. Products via cation intermediates are given from the reactions of acyclic azoalkanes and rearranged products are produced from the reaction of cyclic azo compounds. In many cases, it is known the back electron transfer plays very important role in the PET reaction. Regiochemistry of the reaction between dibenzothiophene radical cation and nucleophiles or nitrogen dioxide C.P. Butts, L. Eberson, M.P. Hartshorn, F. Radner, W.T. Robinson, B.R. Wood Acta Chem. Scandinavica 51:8 (1997) p839-848 PHOTOCHEMICAL NITRATION, ADDUCT FORMATION, TETRANITROMETHANE, DIBENZOFURAN [ @ CHEM: K ] The regiochemistry of nucleophile or radical attack upon dibenzothiophene radical cation (2(.+)) has been studied, using the photolysis of 2-tetranitromethane, the NO2 or nitrous acid catalyzed (NAC) nitration of 2 and the silver(II) mediated acetoxylation of 2 as test reactions in all likelihood mediated by 2(.+). The results are discussed in relation to theoretical predictions based on the VBCM model. The photolysis of the charge-transfer complex of 2 and tetranitromethane in dichloromethane gives mainly dibenzothiophene sulfoxide (3) and minor amounts of 2-nitrodibenzothiophene (4), r-1- hydroxy-c-4-trinitromethyl-1,4-dihydrodibenzothiophene (5), t-2- nitro-r-1-trinitromethyl-1,2-dihydrodibenzothiophene (6) and c-1- nitro-r-4-trinitromethyl-1,4-dihydro-dibenzothiophene 7. In acetonitrile the major product is the sulfoxide 3 together with 2- nitrodibenzothiophene (4) and 4-nitrodibenzothiophene (9). The photolysis in 1,1,1,3,3,3-hexafluoropropan-2-ol yields only the sulfoxide 3 and minor amounts of the 2-nitroarene 4. Nitration of 2 by NO, in dichloromethane gives largely 3 and the 2- nitro isomer 4, as does NAC nitration in acetic acid. The oxidation of 2 by an Ag-II complex of 2,2'-bipyridine gave mainly 1- and 4-acetoxydibenzothiophene and a minor proportion of the 3- acetoxy isomer, no sulfoxide 3 being formed. The X-ray crystal structure is reported for compound 5. Spectrophotometric determination of some pharmaceutical piperazine derivatives through charge-transfer and ion-pair complexation reactions F.M. Abdelgawad J. Pharmaceutical & Biomedical Analysis 15:11 (1997) p1679-1685 PERFORMANCE LIQUID-CHROMATOGRAPHY, BROMOPHENOL BLUE, DOSAGE FORMS, KETOCONAZOLE, PIRIBEDIL, PRAZOSIN, ASSAY, pharmaceutical piperazine derivatives, spectrophotometry, charge- transfer and ion-pair complexes, tablets Simple and sensitive spectrophotometric methods are described for the assay of three piperazine derivatives; ketoconazole, piribedil and prazosin hydrochloride based on charge-transfer and ion-pair complexation reactions. The first method is based on the reaction of the basic drug with 2,3,-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in acetonitrile. The orange-red colour formed due to the formation of charge-transfer complex showed maximum absorbance at 460 nm. The second method is based upon the interaction of the basic drug in dry chloroform with bromophenol blue (BPB) in the same solvent to produce a stable yellow ion-pair complex which absorbs at 410 nm. Beer's law was obeyed for both methods and the relative standard deviations were found to be less than 1%. The two methods can be applied to the analysis of tablets, with no evidence of interference from excipients. A more detailed investigation of the complex was made with respect to its composition, association constant and free energy change. (C) 1997 Elsevier Science B.V. Molecular orientation and aggregation in langmuir-blodgett films of 5-(4-n-octadecylpyridyl)-10,15,20-tri-p-tolylporphyrin studied by ultraviolet-visible and infrared spectroscopies Z.J. Zhang, A.L. Verma, M. Yoneyama, K. Nakashima, K. Iriyama, Y. Ozaki Langmuir 13:16 (1997) p4422-4427 ORDER-DISORDER TRANSITIONS, AIR-WATER-INTERFACE, MONOLAYER ASSEMBLIES, PORPHYRIN, ABSORPTION, LIGHT, 5-(4-CARBOXYPHENYL)-10,15,20-TRITOLYL- PORPHYRIN, 2-OCTADECYL-7,7,8,8-TETRACYANOQUINODIMETHANE, 2-DODECYL- 7,7,8,8-TETRACYANOQUINODIMETHANE, TRANSMISSION [ @ CAV | @ CHEM: D ] The molecular orientation and aggregation behavior of 5-(4-N- octadecyl-pyridyl)-10,15,20-tri-p-tolylporphyrin (porphyrin 338a) in mono- and multilayer Langmuir-Blodgett (LB) films have been investigated by employing ultraviolet-visible (UV-vis) and infrared (IR) spectroscopies. It has been found that the porphyrin planes assume a nearly flat orientation with respect to the surface of the solid substrates in the LB films, irrespective of the number of layers. This orientation remains unaltered even after aging of the LB films for 1 month or heating up to 150 degrees C, indicating high chemical and thermal stabilities of molecular arrangement in the porphyrin LB films. On the other hand, the porphyrin cores are distorted to some extent, and the attached long hydrocarbon chains are loosely packed in the LB films, as deduced from a comparison of the IR spectra of the LB and cast films viith that of the solution. The porphyrin molecules form head-to-tail type (J-type) aggregates in the mono- and multilayer LB films, evidenced by significant red shift of the Soret bands in the UV-vis spectra of the LB films, compared to solution. The comparative and complementary investigations by the UV- vis and IR techniques also suggest that the structural features of the porphyrin mono- and multilayer LB films on CaF2 plate are similar to each other. Mechanism of the oxidation of 3,5,3',5'-tetramethylbenzidine by myeloperoxidase determined by transient- and steady-state kinetics L.A. Marquez, H.B. Dunford Biochemistry 36:31 (1997) p9349-9355 HORSERADISH-PEROXIDASE, HYDROGEN-PEROXIDE, BENZIDINE, SPLEEN, ASSAY, PRODUCT Earlier investigations of the oxidation of 3,5,3',5'- tetramethylbenzidine (TMB) using horseradish peroxidase and prostaglandin H-synthase have shown the formation of a cation free radical of TMB in equilibrium with a charge-transfer complex, consistent with either a two- or a one-electron initial oxidation. In this work, we exploited the distinct spectroscopic properties of myeloperoxidase and its oxidized intermediates, compounds I and II, to establish two successive one-electron oxidations of TMB. By employing stopped-flow techniques under transient-state and steady- state conditions, we also determined the rate constants for the elementary steps of the myeloperoxidase-catalyzed oxidation of TMB at pH 5.4 and 20 degrees C. The second-order rate constant for compound I formation from the reaction of native enzyme with H2O2 is 2.6 x 10(7) M-1 s(-1). Compound I undergoes a one-electron reduction to compound II in the presence of TMB, and the rate constant for this reaction was determined to be (3.6 +/- 0.1) x 10(6) M-1 s(-1). The spectral scans show that compound HT accumulates in the steady state. The rate constant for compound II reduction to native enzyme by TMB obtained under steady-state conditions is (9.4 +/- 0.6) x 10(5) M-1 s(-1). The results are applied to a new, more accurate assay for myeloperoxidase based upon the formation of the charge-transfer complex between TMB and its diimine final product. Functionalization of poly(organophosphazenes) .8. thermally-induced grafting reactions of maleates onto poly[bis(4- ethylphenoxy)phosphazene] M. Gleria, F. Minto, F. Doriguzzi, R. Bertani, G. Facchin, E. Tondello Macromolecules 30:15 (1997) p4310-4317 ETHYLENE-PROPYLENE COPOLYMERS, POLYCARBONATE-POLY(ETHYLENE TEREPHTHALATE) BLENDS, CHARGE-TRANSFER COMPLEXES, FREE-RADICAL REACTIONS, MALEIC-ANHYDRIDE, BULK FUNCTIONALIZATION, REACTION- KINETICS, POLYMERS, POLYPROPYLENE, POLYETHYLENES [ @ CAV | @ SPL: G1.2.10 ] In this paper the radical-induced solution grafting of diethyl maleate onto poly[bis(4-ethylphenoxy)phosphazene] is reported, together with the possible parameters that can influence this reaction, i.e., the maleate, molecular oxygen, and dicumylperoxide concentration in the reaction mixture, the solvent, time, and temperature of the process. A possible mechanism of this process is inferred on the basis of literature data concerning analogous grafting processes carried out onto polyolefins. The importance of the decrease of the intrinsic viscosity of the reaction mixture that takes place during the grafting reaction is also discussed in terms of chain scission and molecular weight degradation of the phosphazene macromolecule. The possible implication of the final phosphazene copolymers containing variable quantities of grafted diethyl succinate groups, poly[bis(4-ethylphenoxy)phosphazene]-g-diethyl succinate, in blending processes with commercial, carbon-backboned macromolecules (polyesters and polycarbonates) is stressed. Quantitative spectroscopic studies of the photoexcited state properties of methano- and pyrrolidino-[60]fullerene derivatives B. Ma, C.E. Bunker, R. Guduru, X.F. Zhang, Y.P. Sun J. Phys. Chem. A 101:31 (1997) p5626-5632 PHOTOINDUCED ELECTRON-TRANSFER, ROOM-TEMPERATURE SOLUTIONS, CHARGE- TRANSFER COMPLEXES, LASER FLASH-PHOTOLYSIS, PHOTOPHYSICAL PROPERTIES, FULLERENES C-60, EXCITATION WAVELENGTH, SOLVENT POLARITY, QUANTUM YIELDS, C-70 UV/vis absorption and fluorescence spectra and fluorescence quantum yields and lifetimes of a series of methano- and pyrrolidino- [60]fullerene derivatives in different solvents are studied systematically. The absorption and fluorescence properties of the derivatives with different substituents are somewhat different from those of [60]fullerene, but very similar among themselves, indicating that the low-lying transitions and the photoexcited state processes are dictated by the electronic structures of functionalized [60]fullerene cages. The results also allow an examination of the issue concerning discrepancies between experimentally determined transition probabilities and those calculated in terms of the Strickler-Berg equation for fullerene molecules. In addition, quenchings of the excited singlet states of the [60]fullerene derivatives by electron donor N,N-diethylaniline (DEA) and the formation of emissive fullerene-DEA exciplexes in solvents of different polarities are investigated. Exciplex fluorescence quenching by lithium perchlorate as a method of investigation of salt dissociation equilibria in solutions M. Mac J. Photochemistry & Photobiology A - Chem. 107:1-3 (1997) p107-113 RADICAL-ION-PAIRS, PHOTOINDUCED ELECTRON-TRANSFER, CHARGE-TRANSFER COMPLEXES, DIELECTRIC-PROPERTIES, MOLECULAR RELAXATION, DIMETHYL CARBONATE, INVERTED REGION, RICH ALKENES, SOLVENTS, DYNAMICS, bimolecular fluorescence quenching, electron transfer process, exciplex formation, special salt effect, salt association equilibria Lithium perchlorate has been found as an effective quencher of the fluorescence of dipolar emitting species such as exciplexes. The quenching efficiency is strongly dependent on the contribution of the charge transfer state in the overall exciplex. The Stern-Volmer plots constructed from the exciplex fluorescence lifetimes, exhibit the nonlinear (downward) curvatures, indicating the partial dissociation of the salt even in strongly polar solvents such as acetonitrile. The detailed numerical analysis of the fluorescence quenching data allows for determination of some important parameters characterizing the salt dissociation equilibria in solutions. The discussion of the credibility of the obtained parameters was performed by comparison with the already published results obtained using different methods. (C) 1997 Elsevier Science S.A. Synthesis, structural and magnetic characterisation of the electron- transfer salts [fe-2(eta-c5me5)(2)(mu-set)(2)(co)(2)](2)[tcnq](2) and [fe-2(eta-c5me5)(2)(mu-set)(2)(co)(2)][tcne] (tcnq equals 7,7,8,8- tetracyanoquinodimethane; tcne equals tetracyanoethylene) R. Buchner, J.S. Field, R.J. Haines J. Chem. Soc. - Dalton Trans. :14 (1997) p2403-2408 DECAMETHYLFERROCENIUM TETRACYANOETHENIDE, 7,7,8,8-TETRACYANO-PARA- QUINODIMETHANE, COMPLEXES, CRYSTAL [ @ CHEM: L | @ SPL: G0.1.3A ] Reaction of the electron-rich thiolate-bridged complex [Fe-2(eta- C5Me5)(2)(mu-SEt)(2)(CO)(2)] with 1 molar equivalent of the electron- acceptor compounds 7,7,8,8-tetracyanoquinodimethane (tcnq) and tetracyanoethylene (tcne) is accompanied by electron transfer and resulted in the formation of the dark green crystalline salts [Fe- 2(eta-C5Me5)(2)- (mu-SEt)(2)(CO)(2)](2)[tcnq](2) 1 and [Fe-2(eta- C5Me5)(2)(mu-SEt)(2)(CO)(2)][tcne] 2 respectively. The crystal structures of these salts have been determined by X-ray diffraction methods and the cations thereof established to have very similar stereochemistries. The C5Me5 ligands are cis disposed with respect to the Fe ... Fe vector with the dihedral angles between their planes being 71 and 68 degrees for 1 and 2 respectively. The Fe ... Fe distances are respectively 3.077(2) and 3.069(2) Angstrom. Crystals of 1 consist of isolated units of composition D.+(A)(2)D-2-(.+) where D.+ denotes the cation and (A)(2)(2-) a (tcnq)(2)(2-) dimer, the planes of the tcnq moieties comprising the dimer and those of the adjacent C5Me5 rings being virtually parallel. The compound is paramagnetic. Crystals of 2 consist of parallel rows of cations and tcne(.-) anions in the sequence ... D(.+)A(A)(.-)D(.+)A(B)(.- )D(.+)A(A)(.-)D(.+)A(B)(.-)..., where A(A)(.-) and A(B)(.-) label crystallographically independent anions. The two types of tcne(.-) anion are themselves approximately planar, but define different angles to the planes of the adjacent C5Me5 rings of 4 and 72 degrees. Magnetic susceptibility measurements for 2, in the range 5.0 to 310.0 K, suggest very little magnetic coupling between the unpaired spins on the cations and the tcne(.-) anions and thus this compound is also paramagnetic. Capping calixarenes with metallodiphosphine fragments: towards intracavity reactions C. Wieser, D. Matt, J. Fischer, A. Harriman J. Chem. Soc. - Dalton Trans. :14 (1997) p2391-2402 TRANSITION-METAL COMPLEXES, SELECTIVE FUNCTIONALIZATION, CRYSTAL- STRUCTURE, OXIDE LIGANDS, UPPER RIM, CALIX<4>ARENES, CONFORMATION, DERIVATIVES, CHEMISTRY, P-TERT-BUTYLCALIX<4>ARENE [ @ CHEM: L | @ SPL: G0.1.3A ]