We report the design, syntheses, structure-property relationships, and applications of alternating copolymers containing heteroaromatic rings. Polymers with different structures were synthesized by Suzuki couplings of 1,4-phenyldiboronic acid with various dibromoarenes. The effect of heteroatoms was studied by comparing polymers containing biphenyl, bipyridine, bithiazole, or thienyl moieties. The changes in the polymer structure led to changes in singlet and triplet energies, absorption and emission properties, as well as energy transfer parameters. The effect of polymer structure on absorption maxima, emission properties, excimer formation, aggregate formation, as well as singlet and triplet energies were studied. Alternating copolymers of bipyridyl moieties gave rise to blue-emitting polymers with emission maxima at 410nm, where as the use of bithiazole moieties red-shifted the emission. All of these polymers can be used in polymer light-emitting devices as the emitting layers, where thienyl containing polymers can be used as hole transport layers. The polymers transferred energy efficiently to Coumarins and europium complexes, allowing for their potential use in longer wavelength emitting applications. The ability of bipyridine containing polymers for use as metal ion sensors was studied.