Abstract: Methods and compositions are provided for forming complexes between dsDNA and novel oligomers comprising fused six-membered rings. By appropriate choice of target sequences and oligomers, complexes comprising oligomer-DNA are obtained with high association constants. The formation of complexes can be used for identification of specific dsDNA sequences, for inhibiting gene transcription, and as a therapeutic for inhibiting proliferation of undesired cells or modulation of expression of specific genes.