Designed synthesis and architectural assembly of head-to-tail polythiophene derivatives provide the ability to control π orbital topology and orbital interactions in conjugated polymers. The preparation of polythiophene derivatives with essentially 100% head-to tail (HT) couplings leads to defect free polythiophenes. These new HT polythiophenes can undergo macromolecular self-assembly to give self-oriented conducting polymers. Study of these materials has led to new insights on structure-property relationships in this class of Materials. In addition, these results show that the molecular orbital overlap, the band dimensionality, and the solid state structure are quite sensitive to the nature of the side chains attached to the polymer's backbone. In addition, we have now synthesized the first heteroatom functionalized HT polythiophenes. These polythiophene derivatives can bind cations, and ion recognition can be used to tune conjugation lengths and properties in polythiophenes. Also presented are a class of random HT coupled 3-alkylthiophenes whose optical and electrochemical properties and possibly electronic properties can be altered by recipe.