[Show abstract][Hide abstract] ABSTRACT: Six hetero-metal clusters RCCo2M(CO)8Cp′ and RCCoM2(CO)7Cp′2 (R = Ph, C2H5O2C; M = Mo, W; Cp′ = CH3Cp) were synthesized by refluxing a solution of the clusters RCCo3(CO)9 and NaM(CO)3Cp′ in THF through metal exchange reactions, in which the metal unit Co(CO)3 in the RCCo3(CO)9 cluster was exchanged by M(CO)2Cp′. The clusters were characterized by elemental analysis, IR and 1H NMR along with the crystal structure of [C2H5O2CCCoMo2(CO)7Cp′2].
[Show abstract][Hide abstract] ABSTRACT: A tetrathiafulvalene derivative — tetrabenzylthiotetrathiafulvalene (TBT-TTF) — is a new material for a conducting Langmuir-Blodgett film. A 1:1 molar mixture with stearic acid was built up to obtain a conducting LB film. The conductivities of this mixed LB film were calculated from experimental results before and after iodine oxidation. To understand the increase in conductivity after iodine oxidation, the IR electronic absorption spectra and X-ray diffraction were investigated. The IR results suggest that the system undergoes continuous free chemical reactions after iodine oxidation. TBT-TTF forms the radical cation dimers associated with I3−. Finally, interaction of this new charge transfer complex (TBT-TTF)x(I3−)1−x (x < 1), gives rise to a new conducting LB film with the highest conductivity (4.7 × 10−2 S cm−1). However, the conducting phase is unstable. The LB film can be oxidized repeatedly by iodine vapour. This is a possible application for gas sensors. The result of X-ray diffraction demonstrates that the molecular reorganization occurs because of tri-iodine chains in the bilayer.
No preview · Article · Sep 1994 · Thin Solid Films
[Show abstract][Hide abstract] ABSTRACT: A new TTF derivative tetrakis(hexadecylthio)-tetrathiafulvalene (THT-TTF) as a Langmuir-Blodgett film material is synthesized. The molecular behavior at the air-water interface is studied by admixture different molar numbers of stearic acid (SA) and a possible molecular reorganization is discussed according to the occupied area per THT-TTF molecule at different SA molar numbers. THT-TTF molecules form dimers, monolayer and intermediate. The ultraviolet (UV) spectra prove this point quantitatively. After iodine oxidation, THT-TTF is not oxidized completely to the cation radical THT-TTF+ from Raman spectra. The formation of triiodide chains has been proved by Raman spectra and UV absorption spectra. Intercalation of the triiodide chain in the bilayers induces the alkyl chains rearrangement and a large reduction in layer thickness. The investigation of conductivities shows that the conductivities are proportional to the THT-TTF molar fraction and that there is a small percolation threshold at Φ∗ = 0.50, which means that THT-TTF is a 2D molecular system. The maximum conductivity reaches 0.9 S cm−1.
No preview · Article · Aug 1994 · Thin Solid Films
[Show abstract][Hide abstract] ABSTRACT: A conducting mixed Langmuir-Blodgett (LB) film of a tetrathiafulvalene (TTF) derivative/stearic acid (SA) mixture is described. An LB film of a 1:1 mixture of a TTF derivative with SA was constructed and examined by Raman, UV, and FT-IR spectroscopies, and X-ray diffraction, and the conductivity at different conditions was studied. The conductivity was 1.3 X 10(-5) S/cm before iodine doping and gradually raised with increasing time of exposure to air, reaching the highest value, 4.7 X 10(-2) S/cm, after iodine doping. This was explained by results of FT-IR spectroscopy and X-ray diffraction. It was due to the formation of a new charge transfer complex-(TBT-TTF) (I3-)x (TBT-TTF) = tetrakis(benzylthio)tetrathiafulvalene) (x < 1)-and the molecular reorganization resulting from the interaction of TBT-TTF/SA with triiodine chains.
[Show abstract][Hide abstract] ABSTRACT: In this paper, the pure C[sub 60] Langmuir-Blodgett (LB) film was built up successfully at a surface pressure of 0 and 25 mN/m. High-resolution electron microscopy and electron diffraction were used to examine the LB film. When surface pressure is 25 mN/m, the electron diffraction pattern of pure C[sub 60] LB film appears highly-symmetric in six spots. According to the calculated results, the C[sub 60] crystallites in the LB film are [r angle]111[l angle] zone of fcc structure with a[sub 0] = 14.14 [angstrom]. 10 refs., 5 figs., 1 tab.
No preview · Article · May 1994 · The Journal of Physical Chemistry
[Show abstract][Hide abstract] ABSTRACT: A conducting Langmuir-Blodgett (LB) film of tetrabenzylthiotetrathiafulvalene-Ni(dmit)2 (TBT-TTF-Ni(dmit)2, where H2dmit is 4,5-dimercapto-1,3-dithiol-2-thione) with stearic acid (SA) was fabricated. The monolayer of (TBT-TTF-Ni(dmit)2)-SA at the air-water interface was studied. The thickness per layer obtained from X-ray diffraction was 2.29 nm. The conductivity of mixed LB films was measured without or with iodine oxidation. Anisotropy of conductivity was observed in the film. After iodine oxidation, with a 0.1 molar fraction of SA the maximum conductivity perpendicular to LB film was 10-2 S cm-1 and parallel to LB film was 40 S cm-1.
No preview · Article · Sep 1993 · Thin Solid Films
[Show abstract][Hide abstract] ABSTRACT: A new charge-transfer complex, TBT-TTF-Cu(dmit)2 (where TBT-TTF is tetrakis(benzylthio)tetrathiafulvalene), as a LB film material is synthesized. The LB films are constructed by using a 1:1 molar mixture of this complex with stearic acid (SA). The degrees of charge transfer are determined to be 0.18 and 0.77 according to Raman frequencies of nu(C-S) and nu(C=C) before and after iodine oxidation. It is shown that the latter mixed-valence compound is formed after continuous changes induced by the iodine intercalation, which leads to the new conducting phase. The existence of triiodide chains has been proved by Raman frequencies and UV absorption spectra. The results of conductivity measurements show that the conductivities increase with an increase in TBT-TTF-Cu(dmit)2 molar fraction and that the LB films exhibit conductive anisotropy. Our results show that we have a 2D percolation system because phi(s)* = 0.50. The maximum conductivity reaches 1.1 S/cm.
No preview · Article · Aug 1993 · The Journal of Physical Chemistry
[Show abstract][Hide abstract] ABSTRACT: In this work, a mixed Langmuir-Blodgett (LB) film was built up using C[sub 60] mixed with arachidic acid (AA) and investigated by FT-IR, UV, Raman, and ESR spectroscopies without or with iodine vapor doping at 60[degrees]C for 18-42 h. The positions of peaks in IR and Raman spectra did not change before and after iodine doping. But the positions of electronic absorption in the UV spectra were shifted by ca. 2-4 nm and six hyperfine splitting lines appeared in ESR signals after iodine doping. According to the experimental results, two possible mechanisms for the interaction of C[sub 60] with I[sub 2] were proposed. 28 refs., 5 figs.
No preview · Article · Jul 1993 · The Journal of Physical Chemistry
[Show abstract][Hide abstract] ABSTRACT: Conductive Langmuir-Blodgett (LB) films were fabricated with a mixture of semiamphiphilic charge transfer complex tetrabenzylthiotetrathiafulvalene-tetracyanoquinodimethane (TBTTTF-TCNQ) with stearic acid (SA). The monolayer of (TBTTTF-TCNQ)-SA at the air-water interface was studied, and the collapse pressure increased with an increase in the molar fraction of SA. The thickness per layer obtained from the results of X-ray diffraction is 2.22 nm. The conductivities of mixed LB films are measured without iodine doping and with iodine doping; the SA content has an effect on the conductivities of mixed LB films. Anisotropy of conductivity was observed in the film. The maximum conductivity of the mixed LB film is 10−2 S cm−1 with a 0.1 molar fraction of SA.
No preview · Article · Mar 1993 · Thin Solid Films
[Show abstract][Hide abstract] ABSTRACT: A conducting Langmuir-Blodgett (LB) film containing a charge transfer complex, tetrabenzylthiotetrathiafulvalene-Zn (dmit)2 (TBTTTF-Zn(dmit)2), where H2(dmit) is 4,5-dimercapto-1,3-dithiol-2-thione, is described. Monolayers at the air-water interface were formed by adding stearic acid (SA) to the semiamphiphilic complex. This was transferred onto solid substrates with SA for IR, UV and conductivity measurements. The thickness per layer was 2.51 nm. The LB films were oxidized with iodine. The maximum conductivities parallel and perpendicular to the LB film were 4.3×10−1 S cm−1 and 10−3 S cm−1 respectively. The LB film exhibited anisotropy of conductivity..
No preview · Article · Jan 1993 · Thin Solid Films
[Show abstract][Hide abstract] ABSTRACT: The carbyne compound [Br(CO)2(Py)2Mo(=CC6H5)] (1) (Py = pyridine) reacts With Co2(CO)8, Fe2(CO)9 and Mn2(CO)10 to give the tetrahedral tri-metal cluster compounds Co2Mo(mu3-CC6H5)Br(CO)8(Py)2 (3), Fe2Mo(mu3-CC6H5)Br(CO)9(Py)2 (4) and Mn2Mo(mu3-CC6H5)Br(CO)10(Py)2 (5), respectively. The tri-metal cluster compound Co2Mo(mu3-CC6H5)Br(CO)8(bipy) (6) is prepared in a similar reaction sequence from [Br(CO)2(bipy)Mo(=CC6H5)] (2) and Co2(CO)8. IR, H-1 and C-13 NMR spectral data of these compounds are reported and discussed. The crystal structure of compound 6 has been determined by X-ray diffraction. It belongs to the monoclinic space group, P2(1)/c, z = 4 a = 9.711(1), b = 17.358(2), c = 17.809(2) angstrom, beta = 97.70(1)-degrees, R = 0.096 for 3185 unique reflections with \I\ > 3sigma(I). The molecule consists of a Co2Mo isosceles triangle of metal atoms (Mo-Co = 2.778(4) and Co-Co = 2.478(5) angstrom) capped by a triply bridging phenylmethylidyne ligand (Mo-C = 2.048(2) and Co-C = 1.942(2) angstrom). Two carbonyls attached to the molybdenum atom are terminal but each of these two carbonyl ligands is semi-bridging to one of the cobalt atoms. The other six carbonyls are all terminal.
No preview · Article · Oct 1992 · Journal of Organometallic Chemistry