Lakhemici Kaboub

Synthesis of new unsymmetrically tetraheterofulvalenes. Study of their radical cation salts.

Chemical modifications of 4,5-bis(cyanoethylseleno) trimethylene tetrathiafulvalene based leading to new donor molecules are described. Electrochemical study of these new TTFs has been carried out. Several of these compounds are readily oxidized to lead to stable conducting radical cations salts and charge transfer complexes.

Structural study and electrical conductivity of salts based on functionalized TTF containing peripheral selenium atoms

Five new substituted tetrathiafulvalene derivatives containing the acetoxyphenyl group as a side-chain have been synthesized using a Wittig-type condensation. Four of them contain peripheral selenium atoms. From cyclic voltammetry data, the electron donor abilities of the obtained compounds have been found to be similar to that of BEDT-TTF. The crystal structures of three of these new donors have been determined. A series of radical cation salts derived from these donors has been obtained by electrocrystallization; the electrical conductivity of these phases measured on compressed powder pellets range from 5 × 10−4 to 4 × 10−5 S cm−1. Charge transfer complexes have also been chemically prepared by using TCNQ as an electron acceptor; the electrical conductivity of their compressed powders range from 0.3 to 0.5 S cm−1. The crystal structure of one of these charge transfer complexes has been determined and shows that the donor and the acceptor entities form regular segregated stacks; its rather high conductivity, actually measured on powder, is in agreement with this structural feature.

Donor–acceptor complex of a new bis-TTF donor containing a pyridine diester spacer with TCNQ as the acceptor: a disappointing system

A new bis-TTF donor (TTF is tetrathiafulvalene) containing a pyridine diester spacer, namely bis{2-[(6,7-tetramethylene-3-methylsulfanyltetrathiafulvalen-2-yl)sulfanyl]ethyl} pyridine-2,6-dicarboxylate-tetracyanoquinodimethane-dichloromethane (2/1/2), 2C(33)H(33)NO(4)S(12) x C(12)H(4)N(4) x 2 CH(2)Cl(2), has been synthesized and its electron-donating ability determined by cyclic voltammetry. The electrical conductivity and crystal structure of this donor-acceptor (DA) complex with TCNQ (tetracyanoquinodimethane) as the acceptor are presented. The TCNQ moiety lies across a crystallographic inversion centre. In the crystal structure, TTF and TCNQ entities are arranged in alternate stacks; this feature, together with the bond lengths of the TCNQ molecule, suggest that the expected charge transfer has not occurred and that the D and A entities are in the neutral state, in agreement with the poor conductivity of the material (sigma(RT) = 2 x 10(-6) S cm(-1)).

Synthesis and Properties of Novel Unsymmetrical Donor Molecules Containing p-Acetoxy- or p-Hydroxyphenyl Units

We report the synthesis and properties of eight new tetrathiafulvalene (TTF) derivatives containing two different functionalities, prepared with the aim of obtaining stable organic materials. The four acetoxyphenyl- and four hydroxyphenyl TTFs were synthesized via Wittig-type condensations. The electrochemical properties of these redox-active molecules were studied by cyclic voltammetry. Charge transfer complexes with tetracyanoquinodimethane (TCNQ) were prepared by chemical redox reactions. The complexes have been proven to give conducting materials. The UV-VIS and IR spectra of the TCNQ salts were recorded and used to characterize and estimate the degree of charge transfer of these complexes.

A bi-TTF with a bipyridine spacer: 4,4′-bis­[(3,6,7-trimethyl­sulfanyltetra­thia­fulvalen-2-yl)sulfanylmeth­yl]-2,2′-bipyridine

The title compound, C30H28N2S16, is a precursor to hybrid magnetic materials. The complete molecule is generated by a crystallographic inversion centre. In the crystal structure, the TTF core is not planar and adopts a chair conformation; the two C3S2 rings are folded around the S⋯S hinges, the dihedral angles being 17.14 (8) and 13.46 (7)°. There is a short S⋯S contact [3.4863  (14) Å] in the crystal structure.

New π-Extended Donors: Synthesis, Characterization, Electrochemical and Electrical Conductivity Studies

A new series of tetrathiafulvalene (TTF) molecules with extended π-system was prepared by using a Wittig reaction to generate the TTF key. The process of deprotection-alkylation of thiolates provided access to a wide variety of molecules. The study of their reducing power was carried out by cyclic voltammetry. Charge transfer complexes have also been chemically prepared by using TCNQ as an electron acceptor; the electrical conductivity of their compressed powders shows insulator behavior. The IR spectra of the TCNQ salts were recorded and used to characterize and estimate the degree of charge transfer of these complexes. GRAPHICAL ABSTRACT