A mononuclear Ni-salphen-type (H-2-salphen = N,N'-disalicylidene-1,2-phenylenediamine) complex was mixed with varying amounts of a dinuclear bis(Ni-salphen)-type complex exhibiting spontaneous helical folding in the crystalline state, and the mixtures were examined by solid-thin-film microscopic transmission absorption spectroscopy at various temperatures. The thermal analysis revealed that the 2:1 mixture displays a eutectic point at 178 degrees C, while the unalloyed mono- and dinuclear complexes melt at 212 and 228 degrees C, respectively. The amorphous film of Ni-salphen displays an absorption band at around 484 nm, which turned into a characteristic fine-structured band upon annealing. Meanwhile, the bis(Ni-salphen) unit in the amorphous film exhibits a band at around 510 nm, which was redshifted to 522 nm upon heating. Annealing of the eutectic mixture at over 180 degrees C resulted in a redshifted profile similar to that of bis(Ni-salphen), implying that the bis(Ni-salphen) crystalline domain induces changes in the molecular arrangement of the Ni-salphen crystal domain.