Defect-free structures of a film composed of linear redox polymer chains were prepared using stepwise cornplexation of Fe(II) and/or Co(II/III) ions with azobenzene-bridged bis(tpy) (tpy = 2,2':6',2 ''-terpyridine) ligands, tpy-AB-tpy, on tpy-terminated SAM on gold. This method realizes a formation of desired number of polymer units (for example, 47-mer Of CO(tpy)(2)) and a desired sequence of Co-Fe heterometal structures in the polymer chain (for example, 10-mer Of CO(tpy)(2) plus 5-mer of Fe(tpy)(2)).