C. Della Casa

Optical properties, conductivity and structure of the DTT-TCNQ CT complex

Abstract The crystal structure, the optical spectra and electrical conductivity of dithieno(3,2-b; 2′,3′-d)thiophene-tetracyanoquinodimethane (DTT-TCNQ) charge-transfer complex have been measured. DTT-TCNQ crystallizes in the monoclinic space group P21/c with a = 7.206(2), b = 7.574(2), c = 32.324(9), β - 92.18(4)°, Z - 4, and the donor and acceptor molecules are arranged in alternated stacks. The low conductivity (a = 10−2 S cm−1 for the single crystal, along the stacking axis a) is characteristic of a semiconductor with activation energy of .61-.76 eV, and is related to the alternate stack structure. Despite the poor condctivity of the DTT-TCNQ CT complex we estimated, from structure and IR data, a low degree of ionicity (p = .2–.3) which characterizes the DTT molecule as an interestign donor. The polarized IR spectra shows the effect of vibronic activation of some of the ag modes of TCNQ.

Solid-state polymerization of 4-amino-4″-carboxy-p-terphenyl

Abstract The synthesis of 4-amino-4″-carboxy- p -terphenyl is reported and a solid-state polycondensation reaction of the synthesized product is studied by thermogravimetry. From the isothermal weightloss-time curves the rates of volatilization of water evolved during the polyamidation reaction were calculated and, by applying the Arrhenius relationship, the activation energy (46 kcal mol −1 ) of the process was obtained. Infrared spectra of the poly[4,4″( p -terphenylene)amide] formed at various temperatures, electrical conductivity data and activation energy values, for both the monomer and polymer, are given.

1H and 13C NMR characterization of poly[3‐(6‐methoxyhexyl)‐2,2′‐bithiophene]

A full 1H and 1C NMR study through the use of one‐ and two‐dimensional techniques (HMQC, HMBC, TOCSY and NOE‐difference spectroscopy) was carried out on poly[3‐(6‐methoxyhexyl)‐2,2′‐bithiophene]. Inter‐ring correlations detected in the HMBC spectra proved to be a valuable tool in the assignment of regiochemistry. NMR data can be interpreted on the basis of a four‐triad model. Copyright

A new simple synthesis of electroconducting triphenodithiazine

Abstract A direct sulfur insertion in N,N′-diphenyl-p-phenylenediamine was carried out to prepare the model oligomeric compound triphenodithiazine (TPDT). During the investigation of the thionation reaction variables some addition compounds, with compositions (TPDT) x S y , were isolated. Iodine doping enhanced the conductivity of the pristine compounds by 8 orders of magnitude, up to 10 −3 S/cm. Differences in iodine content and conductivity were found between TPDT and its sulfur adducts. Finally, the infrared spectrum of doped TPDT was examined.

Synthesis and characterization of poly(3-alkylthiophenes) with NLO chromophoric groups in side chains

Polythiophene copolymers containing alkyl side chains of different length and partially functionalized with chromophoric groups have been synthesized by FeCl 3 oxidative coupling of 3-alkylthiophenes and functionalized 3-alkylthiophenes. Composition, molecular weigth and configuration of the soluble fraction of the copolymers have been investigated and some structure-property correlations have been evidenced.

Synthesis and characterization of semiconducting ladder oligophenothiazines

Abstract The method of direct thionation of N-arylanilino derivatives by elemental sulfur for the preparation of ladder oligophenothiazines is described. A preliminary characterization of the two oligomers, triphenodithiazine and the hitherto unknown tetraphenotrithiazine was made by IR, UV-VIS, ESR, and X-ray diffraction spectroscopy. Unusually high electrical conductivities are reported for the pristine compounds.

Thermally obtained poly [4.4″ (p-terphenylene)-amide]

Abstract A comparison between the poly [4,4″ ( p -terphenylene) amide] obtained from: (1) solid-state polycondensation of the 4-amino-4″-carboxy- p -terphenyl and (2) melt polycondensation of the 4-amino-4″-carbomethoxy- p -terphenyl has been made. As revealed from the thermogravimetric experiments conducted under linear programmation of temperature, i.r. and X-ray analysis, scanning electron microscopy (SEM), and electrical conductivity measurements, the melt obtained polyamide shows a good thermal stability up to 410°C, thereafter undergoes a degradation reaction. The solid-state obtained polyamide is quite stable up to the temperature of 350°C, after which it suffers a crosslinking reaction with formation of a product that is heat resistant at least up to 470°C.

Electrosynthesis and characterization of alkylester-substituted polythiophenes

Thiophenes containing alkylester groups in the β position of the ring have been electropolymerized on Pt. The fraction of the polymer films that became soluble in chloroform has been analysed by spectroscopic techniques and by size exclusion chromatography, with the aim of comparing them with the chemically prepared corresponding macromolecules. The electrochemical behaviour, i.e., the charge process of the polythiophene coatings, has been studied and the relevant parameters have been discussed.

Photoconductivity Of 1, 3, 5-Trithiane Single Crystals

Abstract In continuation of the study of sulphur compounds1,2,3 we were led to examine the electrical behaviour of 1,3,5-trithiane, We think that the photoconductivity of single crystals of 1,3,5-trithiane is mainly extrinsic. The photocurrent action spectrum shows a maximum at 235 nm, the intensity of which varies appreciably with the presence of defects introduced onto the surface by means of thermal treatments or ageing. The dependence of the photocurrent on the incident light intensity is found to be sublinear.