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Abstract Conjugated oligomers and polymers have attracted huge interest in recent years owing to their potential applications for electronic devices. Various heterocyclopentadienes (thiophene, pyrrole, furan, etc….) have been incorporated into the backbone of -conjugated systems since their electronic properties are dependent on the nature of the heteroatom. Phospholes show electronic properties that are markedly different from those of thiophene and pyrrole. The electronic and geometric properties of phosphole oligomers will be examined for fine-tuning their electronic properties via grafting the parent oligomer with electron donation/withdrawing substituents. The investigated systems are (X-phosph)n, where X is -NHCH3, - OCH3 or –F substituent and n is the number of units (n=1-7). The substitutions were considered at C of the ring with three different oligomerization modes, head to head (HH), head to tail (HT) and tail to tail (TT), or that of P-centers. It is expected that the changes in the geometrical and electronic structures by the influence of substitution will lead to modifying the electrical properties as well. All electronic structure calculations have been carried out using the Gaussian 03 program package. Geometries of the neutral and the singly charged oligomers were fully optimized at the B3LYP/6-31G(d) level. |