Host-guest chemistry of giant molecular shape amphiphiles based on POSS-PDI conjugates

Facile Synthesis and Photoluminescent Properties of Asymmetric Perylene Diimides Capable of Tuning Emission Colors in Polymeric Matrices

We report the facile synthesis of asymmetric perylene diimides (asym-PDIs) using readily available reagents, demonstrating their distinct photoluminescent properties. In CHCl3, asym-PDIs exhibit higher solubility compared to traditional perylene dyes, of which solubilities can be varied by substituent selections. Among them, UV-vis absorption spectra of CPE in CHCl3 solution displayed no aggregate peaks in the ground state, maintaining high photoluminescent quantum yields. Also, CPE can be readily dispersed into poly(methyl methacrylate) PMMA (CPE-PMMA), forming thin films without aggregate formation. Importantly, the emission color of CPE-PMMA thin films significantly changes with the addition of polycyclic aromatic hydrocarbons (PAHs). These color changes should be strongly correlated with the HOMO level of the added PAHs.

Aqueous Self-Assembly of Hydrophobic Molecules Influenced by the Molecular Geometry

Water, in addition to acting as a solvent, plays a constructional role in aqueous self-assembly. The hydrophobic molecule of POSS-PDI-POSS (POSS = polyhedral oligomeric silsesquioxanes, PDI = perylene diimide) has a shape anisotropy in which POSS is a ball-like bulky group and PDI is a flat aromatic group. The self-assembly of this molecule in water created assemblies with inner spaces due to the steric effect, which suppressed aromatic interactions of PDI and trapped water for the colloidal stability. By replacing POSS with dodecyl (C₁₂), C₁₂-PDI-C₁₂ aggregated with extended aromatic interaction of PDI and less inner water. The resulting aggregates tended to agglomerate and precipitate. This discovery extended the scope of aqueous self-assembly by using the building blocks without amphiphilicity and created knowledge for biophysics.

Porous polymers from octa(amino-phenyl)silsesquioxane and metalloporphyrin as peroxidase-mimicking enzyme for malathion colorimetric sensor

Rapid and efficient pesticide detection methods are particularly important due to the growing problems of pesticide residues. Here, a new azo-based porous organic polymer, Azo(Fe)PPOP, was prepared from octa(amino-phenyl)silsesquioxane (OAPS) and iron(III) 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (FeTPP(NO₂)₄) via a simple coupling reaction without the participation of metal catalysts. The inorganic cage units of OAPS endowed Azo(Fe)PPOP a porous framework, high surface area, favorably thermal and chemical stability. In Azo(Fe)PPOP, iron(III) porphyrin units were individually isolated in a fixed location, which could effectively avoid dimerization or self-oxidation as happens as in the case of porphyrin monomers. Such a unique structure made Azo(Fe)PPOP exhibit an excellent peroxidase-like catalytic performance in the presence of H₂O₂ and 3,3',5,5'-tetramethylbenzidine (TMB). Because of these advantages, we established a selective, facile, and sensitive colorimetric platform for direct detection of malathion within a very short time (3 min) with a low detection limit (8.5 nM). In addition, the recognition mechanism between Azo(Fe)PPOP and malathion was verified using X-ray photoelectron spectroscopy spectra. The practicality of the constructed platform was further executed by the detection of the pesticide in soil and food samples.