Adsorption and photochemical behavior of Pt(II)meso-tetra(N-methyl-4-pyridinium)porphyrin (PtTMPyP) on clay (saponite) nanosheet surface were investigated. PtTMPyP was adsorbed up to 70% vs. cation exchange capacity (CEC) of clay nanosheet. It was turned out that the phosphorescence of PtTMPyP was enhanced by the adsorption on the clay surface compared to that in water. These results can be understood as Surface-Fixation Induced Emission (S-FIE) phenomenon. In addition, interestingly, PtTMPyP showed non self-phosphorescence quenching behavior on the clay nanosheet surface even under the high density adsorption conditions up to 80% vs. CEC. This unique phenomenon was discussed by a comparison with Zn(II)meso-tetra(N-methyl-4-pyridinium)porphyrin (ZnTMPyP) as a reference dye.

Food loss is an important issue from the view-point of SDGs (Sustainable Development Goals) movement. Motivated by this trend, the present work manufactured a colored solid substance based on anthocyanin dyes contained in purple cabbages. Anthocyanin dyes were effectively extracted by ethanol under ultrasonic treatment. Various kinds of divalent and trivalent metal ions were added in order to tune color tone. As a result, Al³⁺ ion was found to stabilize blue color from original purple one. To achieve a solid form, extracted dyes were adsorbed by synthetic saponite. The resultant hybrid compounds consisting of anthocyanins, Al³⁺ and synthetic saponite were analyzed by means of XRD and diffusion reflection spectra. The stability of colored substances at higher temperature was examined.

The adsorption behavior of sulfate (SO₄²⁻) on pseudoboehmite with or without surface complexation of citrate, oxalate, and acetate was investigated to elucidate the effect of low-molecular-weight organic acids on their sulfate adsorption. The adsorption experiments were conducted using reaction systems containing 0.01 g of pseudoboehmite with or without organic complexation and 10.0 mL of a mixed solution consisting of 10, 100, or 1000 µmol/L sulfate and background electrolyte of 1.0 mmol/L NaCl at pH conditions ranging from 3 to 10. An attenuated total reflectance-Fourier transform infrared analysis (ATR-FTIR) was conducted to confirm the surface organic complexes, and geochemical calculations were performed to examine the reaction process in solution. The results indicated that sulfate adsorption on the pseudoboehmite with no organic complex (PBM-NO) increased progressively as solution pH decreased from 9 to 6, whereas the adsorbed amount decreased successively at pH <5 because of the formation of free Al-sulfate complex ions mainly as AlSO₄⁺ in this acidic region. The pseudoboehmite complexed with citrate (PBM-Cit) and oxalate (PBM-Oxa) exhibited lower sulfate adsorption than the PBM-NO due to the site blocking by the organic acids. However, the sulfate adsorption increased successively until the solution pH decreased to about 3 with no decrease in sulfate adsorption at pH <5 as observed in the PBM-NO. The ATR-FTIR and geochemical calculations indicated that the no decrease in sulfate adsorption was attributed to inhibition of the Al-sulfate complex formation due to the preferential complexation of dissolved free Al³⁺ with citrate or oxalate molecules released from the surface of the PBM-Cit and PBM-Oxa. The pseudoboehmite complexed with acetate exhibited a sulfate adsorption behavior similar to that of the PBM-NO due to the low complexation ability of acetate with the pseudoboehmite surface.

Ion-exchange, reconstruction, and coprecipitation approaches were used to examine the composite formation of layered double hydroxides (LDHs) and glycyrrhizic acid. The use of reconstruction and coprecipitation approaches successfully intercalated the glycyrrhizic acid dipotassium salt into the LDH interlayer space, which enhanced moisturization. Furthermore, the uptake of glycyrrhizic acid in the composite synthesized using the coprecipitation approach was higher than that of the composite by the reconstruction approach. Additionally, the moisture content of the coprecipitated composite to skin was found to be higher than that of the pristine glycyrrhizic acid dipotassium salt, thereby strongly demonstrating the advantages of using LDHs for the generation of composites with higher moisture content.