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The synthesis, structure, redox and photophysical properties of the two- and three-layered donor-acceptor (D-A) type [3.3]paracyclophanes ([3.3]PCPs) are presented. The (p-ethylbenzenesulfonyl)methyl isocyanide coupling method is used for achieving the synthesis of the two- and three-layered [3.3]PCPs containing 2,1,3-benzothiadiazole (BTD) as an acceptor.

B3LYP calculations are used for studying the reaction mechanism of the aminolysis of Fischer carbene complexes of the type [(CO).sub.5]Cr[double bond]C(XMe)R (X = O and S, R = Me and Ph). The results have shown that the transition state of the nucleophilic attack is more advanced and has a higher barrier for alkoxycarbene than thiocarbene complexes because of the stronger [pi]-donor character of the alkoxy group that has reduced the electrophilicity of the attacked carbene atom making the nucleophilic attack more difficult.

The synthesis and characterization of two new boron-based conjugated compounds containing one and three monopyrrolo-annelated tetrathiafulvalene (TTF) units. The absorption spectral and electrochemical responsiveness of these compounds toward fluoride ion is because of the binding of the boron units with fluoride ion.

A new n-channel semiconductor class is described for organic field-effect transistors (OFETs) based on thienoquinoidal structures. Solution-processed FETs based on the terthienoquinoid derivative with ((n-alkyloxy)carbonyl)cyanomethylene moieties have displayed good electron mobilities under ambient conditions.

An electrochemical STM setup was employed to study the electron transport characteristics in redox molecule-modified tunneling junctions Au(111)/6-thiohexanoylferrocene (Fc6)/solution gap/Au STM tip in the absence and in the presence of gold nanoclusters. The results demonstrated the power of the electrochemical approach in molecular electronics and offered a new perspective toward two-state and multistate electronic switching in condensed media at room temperature.

A highly regioselective 1,3-dipolar cycloadditions of exTTF-containing azomethine ylides to the endofullerene was performed to synthesize the stable donor-acceptor conjugates involving an endohedral metallofullerene, [La.sub.2]@[I.sub.h]-[C.sub.80], and [pi]-extended tetrathiafulvalene (exTTF). The results provide insight into the redox active character of the system due to the presence of both donor and acceptor groups and the electrochemically reversible character of the endofullerene which confirms the presence of the [5,6] adduct.

The synthesis and characterization of four ladder-type oligo-p-phenylene containing donor-acceptor copolymers are described. The ladder-type oligo-p-phenylene is used as an electron donot unit in the copolymers to provide a deeper highest occupied molecular orbital (HOMO) level for obtaining polymer solar cells with a higher open-circuit voltage, while 4,7-dithien-2-yl-2,1,3-benzothiadiazole of 5,8-dithien-2-yl-2,3-diphenylquinoxaline is chosen as an electron acceptor unit to tube the electronic band gaps of the polymers for a better light harvesting ability.

The design and synthesis of a new low-band-gap thieno[3,4-c]pyrrole-4,6-dione-based copolymer (PBDTTPD) is described. The polymer when blended with P[C.sub.71BM has shown a power conversion efficiency of 5.5% in a bulk-heterojunction photovoltaic device having an active area of 1.0 [cm.sup.2].

The development of metal-free organic sensitizers is very important in dye-sensitized solar cells and photovoltaic conversion with a new class of stable tetrathiafulvalene derivatives has shown electrochemical and kinetic properties. The proof-of-concept has shown that sensitizers with a small driving force has operated functionally in dye-sensitized solar cells and has helped in reducing photovoltage losses due to poor energetic alignment of the materials.

A spin-polarized donor (BTBN) is prepared that is a dibromotetrathiafulvalene derivative containing a nitronyl nitroxide group in a cross-conjugated manner. The results have shown that the transport of carriers in the neutral unicomponent radical crystal is controlled by the external magnetic field, which are important for developing molecule-based spin electronic devices.

A combination of substituent effects is used for describing the design, synthesis, isolation and characterization of the first persistent nonacene derivative. The powerful substituent effects are suitable for preparing other persistent, soluble, large acene derivatives needed for advanced thin-film organic semiconductor applications.

A nanofabricated mechanically controllable break junction was used to fabricate Au-TTF-Au (tetrathiafulvalene, TTF) and Au-TSF-Au (tetraselenafulvalene, TSF) single-molecule junctions. The difference observed in single-molecule conductances of the two types of junctions originated from the difference in the strength of the molecule-electrode coupling through face-to-face overlapping configurations.

The synthesis of a new series of electron donor-acceptor conjugates in which the electron acceptor-[C.sub.60]-and the electron donor-[pi]-extended tetrathiafulvalene (exTTF)-are bridged by using m-phenyleneethynylene spacers of variable length is described. AFM spectroscopy is used for showing the ability of these new conjugates to form wirelike structures upon deposition onto a mica surface.

The preparation, analysis and carrier generation mechanism of self-doping in a tetrathiafulvalene (TTF) conductor, ammonium tetrathiafulvalene-2-carboxylate (TTFCO[O.sup.-]N[H.sub.4.sup.+]), are described along with molecular orbital characteristics. TTFCO[O.sup.-]N[H.sub.4.sup.+] is described as a 'hydrogen-bonding-assisted self-doped conductor' and the contribution of the hydrogen-bonding interaction to the electron conduction is supported by a large isotope effect in the ac conductivity.