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This article presents a study on the exceptionally small attenuation factors in molecular wires. The potential of molecular-sized materials for electronic and photonic applications has led to an ever increasing interest in developing and probing molecular-scale wires) &b.pie;-Conjugated oligomers, such as oligo p-phenylenevinylenes, oligo-PPVs, are among those molecules which act as efficient molecular wires. Only a few reports on electron transfer through the &b.pie;-conjugated chains of oligo-PPVs are known. In this light, the importance of energy matching between the donor and bridge components, for achieving molecular-wire behavior, has been highlighted.

Several generations of phenylenevinylene dendrons, covalently attached to a C[sub 60] core, have been developed as synthetic model systems with hierarchical, fine-tuned amhitectures. End-capping of these dendritic spacers with dibutylaniline or dodecyloxynaphthalene, as antennas/electron donors, yielded new donor-bridge-acceptor ensembles in which one, two, or four donors are allocated at the peripheral positions of the well-defined dendrons, while the electron accepting fullerene is placed at the focal point of the dendren. On the basis of our cyclic voltammetry experiments, which disclose a single anodic oxidation and several cathodic reduction processes, we rule out significant, long-range couplings between the fullerene core and the end-standing donors in their ground-state configuration. Photophysical investigations, on the other hand, show that upon photoexcitation an efficient and rapid transfer of singlet excited-state energy (6 × 10[sup 10] to 2.5 × 10[sup 12] s[sup -1]) controls the reactivity of the initially excited antenna portion. Spectroscopic and kinetic evidence suggests that yet a second contribution, that is, an intramolecular electron-transfer, exists, affording C[sub 60]·-dendron·+ with quantum yields (φ) as high as 0.76 and lifetimes (τ) that are on the order of hundreds of nanoseconds (220-725 ns). Variation of the energy gap modulates the interplay of these two pathways (i.e., competition or sequence between energy and electron transfer). [ABSTRACT FROM AUTHOR]

The synthesis, structural, electrochemical, and thin film electrical and electronic structural properties of a series of arylene diimide-oligothiophene n-type semiconductors are reported. This family of compounds allows analysis of the effects on thin film transistor performance of the following: (i) oligothiophene backbone catenation; (ii) naphthalenediimide vs perylenediimide core interchange; (iii) phenylene group introduction in the oligothiophene backbone. Electrochemical experiments indicate similar redox energetics for all members of this series, while thin film transistor measurements reveal markedly different charge transport performances. The highest electron mobility of 0.35 cm(2) V(-1) s(-1) is recorded for films of benzo[lmn]thieno[3',4':4,5]imidazo[2,1-b][3,8]phenanthroline-1,3,6(2H)-trione, 2-octyl (NDI-1T). Solution-processed field effect transistors were also fabricated and surprisingly exhibit electrical performances surpassing that of the vapor-deposited films in the case of isoquino[6',5',4':10,5,6]anthra[2,1,9-def]thieno[3',4':4,5]imidazo[2,1-a]isoquinoline-1,3,8(2H)-trione, 2-(1-heptyloctyl)-10,12-di-2-thienyl (PDI-3T).