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Several reactions are conducted for the development of a series of various six-ring oligothiophenes containing one to three degrees of ring fusion. The different effects of position and extent of ring fusion on the electronic properties of the compounds are also explained.

Both homo- and heterosequence m-phenylene ethynylene oligomers are synthesized using a conceptually simple interative solid-phase strategy. The method is found to considerably reduce the time required for the construction of phenylene ethynylene oligomers, which in turn would allow for a more in-depth investigation into their sequence variations.

The facile synthesis of oligomers of hexa-peri-hexabenzocoronene (HBC), up to trimers (3,4, 5a-c) with different modes of connection is presented and a methylene-bridged HBC dimer, so-called 'superfluorene' was prepared for comparison. The induced planarity improves pi-conjugation and suppresses the geometrical relaxation of the backbone upon electronic excitation, leading to a prominent 0-0 transition band in the fluorescence spectra.

The analysis of chain length dependence of the electronic, electrochemical, and vibrational properties of the three series of oligomers is carried out using cyclic voltammetry and Raman spectroscopies. The results show that incorporation of ethylenic linkages in an oligothiophene structure leads to faster decrease of the HOMO-LUMO gap with chain extension due to the combined effects of enhanced planarity and lower overall aromatic character of the system.