We have found giant negative magnetoresistance in the one-dimensional conductor $\mathrm{TPP}\left[\mathrm{Fe}\right(\mathrm{Pc}\left)\right(\mathrm{CN}{)}_2{]}_2$ below 50 K. The reduction of the resistance is larger in the field perpendicular to the one-dimensional axis than parallel to the axis. The magnetic susceptibility shows anisotropic Curie-Weiss behavior. The experimental results suggest the interaction between the one-dimensional electron system and the local moments. The reduction of the spin scattering of the itinerant electrons by the local moments under the field is proposed as the origin of the giant negative magnetoresistance.

A conducting partially oxidized salt of TPP[Fe(Pc)(CN)₂]₂, which contains paramagnetic iron(III), has been obtained by electrocrystallization of TPP[Fe(Pc)(CN)₂]. The crystal is composed of one-dimensional TPP arrays surrounded by slipped-stacked one-dimensional Fe(Pc)(CN)₂ chains. This structure is isomorphous with TPP[Co(Pc)(CN)₂]₂, in which the central metal is non-magnetic cobalt(III). The electrical conductivity at room temperature, ca. 10 Ω⁻¹ cm⁻¹, is about one order of magnitude lower than that of the Co analogue. On lowering the temperature, the conductivity shows a much steeper decline compared with the temperature dependence of the conductivity of TPP[Co(Pc)(CN)₂]₂. The band width, estimated from both thermoelectric power measurements (which show apparent metallic behavior at high temperatures) and an extended Hückel calculation, is found to be the same as that obtained for TPP[Co(Pc)(CN)₂]₂. This is consistent with observations from the single-crystal reflectance spectra, in which both partially oxidized salts show almost the same plasma edge. On the other hand, the magnetic susceptibility of TPP[Fe(Pc)(CN)₂]₂ is quite different from that of TPP[Co(Pc)(CN)₂]₂; both of the magnetic moments originated from Fe^III and the π-radical seem to be localized in TPP[Fe(Pc)(CN)₂]₂, while the moments originated from the π-radical in TPP[Co(Pc)(CN)₂]₂ are interacting with each other to lead to temperature-independent Pauli-like susceptibility. At low temperatures, a decrease in the susceptibility has been observed, suggesting the existence of antiferromagnetic interactions.

A film of a spin-crossover complex [Fe(dpp)2](BF4)2 (dpp = 2,6-di(pyrazol-1-yl)pyridine) was embedded into the light-emitting layer of an organic electroluminescent (EL) device with chlorophyll a. While the EL spectrum was observed at 300 K, the spectrum could not be observed at 200 K. The temperature dependence of the EL spectra shows the quenching of the emission below 260 K, which is the spin-transition temperature of [Fe(dpp)2](BF4)2. This suggests that the EL quenching accompanied the spin transition.

Thin film of a spin crossover complex [Fe(dpp)2](BF4)2 (dpp = 2,6-di(pyrazollyl)pyridine) has been fabricated by a spin-coating method. The obtained film exhibits spin transition at around 260 K. The absorption spectra and the electrical resistance change with the spin transition. These phenomena are reproducible through both cooling and heating process.

Electrochemical oxidation of PTMA[M^III(Pc)(CN)₂] (PTMA = phenyltrimethylammonium, Pc = phthalocyaninato, and M = Co or Fe) gives partially oxidized salts (PTMA)_x[M^III(Pc)(CN)₂]·y(solvent) (solvent = acetonitrile or acetone). The obtained crystals in which the solvent molecules partially occupy the cationic sites are isomorphous regardless of M and solvent. They are highly conducting and metallic behavior is observed in the conductivity and thermoelectric power measurements. In contrast to the Pauli-like behavior of the Co^III salt, Curie-like behavior with an anomaly due to antiferromagnetic interactions was observed for the Fe^III salt in magnetic susceptibility measurements. The existence of local magnetic moments in the Fe^III salt leads to a significant influence on the transport properties, suggesting the existence of π–d interactions in this system.