Progress of Multi Functional Properties of Organic-Inorganic Hybrid System, A[FeIIFeIIIX3] (A = (n-CnH2n+1)4N, Spiropyran; X = C2O2S2, C2OS3, C2O3S)

Abstract

In the case of mixed-valence systems whose spin states are situated in the spin crossover region, new types of conjugated phenomena coupled with spin and charge are expected. From this viewpoint, we have investigated the multifunctional properties coupled with spin, charge and photon for the organic-inorganic hybrid system, A[FeIIFeIIIX3](A = (n-CnH2n+1)4N, spiropyran; X = dto(C2O2S2), tto(C2OS3), mto(C2O3S)). A[FeIIFeIII(dto)3] and A[FeIIFeIII(tto)3] undergo the ferromagnetic phase transitions, while A[FeIIFeIII(mto)3] undergoes a ferrimagnetic transition. In (n-CnH2n+1)4N [FeIIFeIII(dto)3](n = 3,4), a new type of phase transition called charge transfer phase transition (CTPT) takes place around 120 K, where the thermally induced charge transfer between FeII and FeIII occurs reversibly. At the CTPT, the iron valence state dynamically fluctuated with a frequency of about 0.1 MHz, which was confirmed by means of muon spin relaxation. The charge transfer phase transition and the ferromagnetic transition for (n-CnH2n+1)4N[FeIIFeIII(dto)3] remarkably depend on the size of intercalated cation. In the case of (SP)[FeIIFeIII(dto)3](SP = spiropyran), the photoinduced isomerization of SP under UV irradiation induces the charge transfer phase transition in the [FeIIFeIII(dto)3] layer and the remarkable change of the ferromagnetic transition temperature. In the case of (n-CnH2n+1)4N[FeIIFeIII(mto)3](mto = C2O3S), a rapid spin equilibrium between the high-spin state (S = 5/2) and the low-spin state (S = 1/2) at the FeIIIO3S3 site takes place in a wide temperature range, which induces the valence fluctuation of the FeS3O3 and FeO6 sites through the ferromagnetic coupling between the low spin state (S = 1/2) of the FeIIIS3O3 site and the high spin state (S = 2) of the FeIIO6 site.

Control of electronic polarization via charge ordering and electron transfer: electronic ferroelectrics and electronic pyroelectrics

“…Among them, only [( n -C 4 H 9 ) 4 N][Fe III Fe II (dto) 3 ] exhibits charge transfer phase transition, whereas the other two compounds with n = 5 and 6 don't show such phase transitions. 70 …”

“…Thus, [(n-C 3 H 7 ) 4 N] [Fe III Fe II (dto) 3 ] has received attention owing to its molecular [Fe III Fe II (dto) 3 ] exhibits charge transfer phase transition, whereas the other two compounds with n = 5 and 6 don't show such phase transitions. 70 Recently, the electric polarization properties of [(n-C 3 H 7 ) 4 N] [Fe III Fe II (dto) 3 ] have been investigated in depth. The P-E curve of a lm of [(n-C 3 H 7 ) 4 N][Fe III Fe II (dto) 3 ] measured at 300 K shows a clear polarization hysteresis in the in-plane direction (Fig.…”

Improving the flame retardancy and mechanical properties of poly(lactic acid) with a novel nanorod-shaped hybrid flame retardant

“…The hybrid materials have broad potential applications as nano llers. 21,22 Methods to synthesize inorganic-organic hybrid materials are oen based on so chemistry approaches, such as sol-gel process, intercalation, exchange, or graing. Benzenephosphinic acid (BPA) is not applied in PLA as an additive ame retardant because the carboxyl group in BPA could react with PLA during melt processing and in use, which results in the depolymerization of PLA molecules and the deterioration to the performances of the PLA composites such as mechanical properties.…”