Stabilization of cationic zinc phthalocyanine monomers by adsorption on clay nanosheet colloid and photogeneration of singlet oxygen

Adsorption of Dye Molecules and Its Potential for the Development of Photoactive Hybrid Materials Based on Layered Silicates

The present paper gives a brief account of the latest advances in understanding of the mechanism and implications of dye adsorption with a special focus on layered silicate surfaces. It has been clearly demonstrated that the controlled adsorption of novel or already well-known dyes has equally great yet unexplored potential. In principle, the well-engineered surface confinement of the molecules may lead to their aggregation, adsorption, or intercalation-induced fluorescence emission even with conventional dyes, which are not considered as luminophores in solutions or in the solid state. We envision the utilization of silicate-based heterogeneous systems to produce novel polymer blended films or structured liquids, as well as to develop a plethora of other photophysical and biomedical applications.

Tetrazolyl Porphyrin-Based Hydrogen-Bonded Organic Frameworks: Active Sites-Mediated Host-Guest Synergy for Advanced Antimicrobial Applications

Hydrogen-bonded organic frameworks (HOFs) with multiple functions and permanent pores have received widespread attention due to their potential applications in gas adsorption/separation, drug delivery, photocatalysis, proton conduction, and other fields. Herein, we constructed a three-dimensional (3D) HOF with 1D square channels by utilizing a dual-functional tetrazolyl porphyrin ligand bearing an active center of the porphyrin core and open sites of nitrogen atoms through π-π stacking and hydrogen-bonding interaction self-assembly. The structure exhibits both solvent resistance and thermal stability, and especially, maintains these after being transformed into nanoparticles. Meanwhile, the active sites exposed on the inner wall of the pores can interact well with the photoactive cationic dye molecules to form an effective host-guest (H-G) system, which can realize boosted photosensitized singlet oxygen (1O2) production under red light irradiation and synergistic sterilization toward Staphylococcus aureus (S. aureus) with an inhibition ratio as high as 99.9%. This work provides a valuable design concept for HOF-related systems in pursuit of promoted photoactivity.

"In-water" Dehydration Reaction of an Aromatic Diol on an Inorganic Surface

The effect of a synthetic saponite surface on the "in-water" dehydration reaction of diol was examined using 4-formyl-1-methylquinolinium salt (MQu⁺) as a substrate. The equilibrium between aldehyde (MQu⁺-Aldehyde) and diol (MQu⁺-Diol) was affected by the surrounding environment. The equilibrium behavior was observed by ¹H nuclear magnetic resonance (NMR) and UV-vis absorption measurements. Although MQu⁺ was completely in the form of MQu⁺-Diol in water, the equilibrium almost shifted to the MQu⁺-Aldehyde side when MQu⁺ was adsorbed on the saponite surface in water. In addition, the MQu⁺-Aldehyde ratio depended on the negative charge density of saponite. The factors that determine MQu⁺-Aldehyde: MQu⁺-Diol ratio were discussed from the thermodynamic analysis of the system. These data indicate that the electrostatic interaction between the charged saponite surface and MQu⁺ stabilized the aldehyde side enthalpically and destabilized it entropically. The major reason for these results is considered to be the difference in adsorption stabilization between MQu⁺-Aldehyde and MQu⁺-Diol on saponite surfaces.