Silica microspheres functionalized with porphyrin as a reusable and efficient catalyst for the photooxidation of 1,5-dihydroxynaphthalene in aerated aqueous solution

Superior Photophysical and Photosensitizing Properties of Nanoaggregates of Weakly Emissive Dyes for Use in Bioimaging and Photodynamic Therapy

The development of luminescent dyes based on 1,1,4,4-tetracyanobuta-1,3-dienes (TCBDs) is an active research area, and a quantum yield (ΦF) of 7.8% has been achieved so far in cyclohexane by appending a fluorophore. Our novel method radically refines weakly emissive 2,3-disubstituted TCBD (phenyl-TCBD 1) (ΦF = 2.3% in CH3CN) into a water-soluble, biocompatible nanoformulation as highly emissive aggregates 1NPs ⊂ PF-127 with ΦF = 7.9% in H2O and without fluorophore conjugation. Characterization of 1NPs ⊂ PF-127 was carried out using various spectroscopic techniques, and its predominant size was found to be 80-100 nm according to transmission electron microscopy and dynamic light scattering techniques. Spectroscopic studies including Fourier transform infrared spectroscopy revealed that aggregated phenyl-TCBD particles were encapsulated in a nonluminescent triblock copolymer (PF-127)-based nanomicelles with the TCBD entrapment efficiency of 77%. With increasing water fraction, the phenyl-TCBD nanoaggregates exhibited a 3-fold higher quantum yield, a greater lifetime, and a red shift (155 nm). This remarkable enhancement in red emissivity enabled them to be used as a bioprobe for bioimaging applications and in photodynamic therapy to selectively target cancer cell lines with singlet oxygen generation capability (ΦΔ = 0.25). According to the MTT assay, compared to the native molecular form (1229 nM), the aggregated 1NPs ⊂ PF-127 (13.51 nM) exhibited dose-dependent cell death when exposed to light with 91-fold increased activity. The histoarchitectures of various vital organs (liver, kidneys, heart, lungs, and spleen) were intact when tested for in vivo biocompatibility. This study has significant implications for developing nonplanar push-pull chromophore-based dyes as biosensors and with potential applications beyond bioimaging.

Recent advances in metalloporphyrins for environmental and energy applications

Porphyrin-based chemistry has reached an unprecedented period of rapid development after decades of study. Due to attractive multifunctional properties, porphyrins and their analogues have emerged as multifunctional organometals for environmental and energy purposes. In particular, pioneer works have been conducted to explore their application in pollution abatement, energy conversion and storage and molecule recognition. This review summarizes recent advances of porphyrins chemistry, focusing on elucidating the nature of catalytic process. The Fenton-like redox chemistry and photo-excitability of porphyrins and their analogues are discussed, highlighting the generation of high-valent iron oxo porphyrin species. Finally, challenges in current research are identified and perspectives for future development in this area are presented.

Supramolecular Confinement within Chitosan Nanocomposites Enhances Singlet Oxygen Generation

The synthesis of water-soluble chitosan nanocomposites incorporating BODIPY and the investigation of their photosensitization properties is reported. It was observed that the singlet oxygen generation capability of nanocomposites containing a mixture of BODIPY and iodine-containing molecules are higher than that of the nanocomposites containing BODIPY alone. It is hypothesized that the supramolecular interactions between BODIPY and iodine-containing molecules confined within the nanocomposites lead to the enhanced singlet oxygen generation.

Interfacial fabrication of functional supramolecular polymeric networks for photocatalysis

Supramolecular polymeric networks based on host-enhanced π-π interaction have been obtained at a liquid-solid interface through the layer-by-layer (LbL) assembly of porphyrin bearing four naphthalene groups and cucurbit[8]uril. The fabricating progress of supramolecular networks at interface can be efficiently controlled, simply by adjusting the layer-pair number of LbL films. Moreover, upon irradiation of visible light, these supramolecular networks exhibit good catalytic features for the oxidation of various phenols. It is anticipated that this strategy of fabricating supramolecular polymeric networks at the interface has potential applications in the fields of sewage disposal and biocatalysis, just to name a few.

Photoactive, porous honeycomb films prepared from Rose Bengal-grafted polystyrene

Honeycomb-structured porous polymer films based on photosensitizer-grafted polystyrene are prepared through the breath figure process. Rose Bengal (RB) photosensitizer is first attached to a well-defined poly(styrene-stat-4-vinylbenzyl chloride) statistical copolymer, synthesized by nitroxide-mediated radical polymerization. The RB grafted poly(styrene-stat-4-vinylbenzyl chloride) (ca. 20,000 g mol(-1) molar mass, 1.2 dispersity) leads to porous polymer films, with a hexagonal pore pattern, while a simple mixture of poly(styrene-stat-4-vinylbenzyl chloride) and the insoluble RB photosensitizer produced unstructured, nonporous films. The RB-grafted honeycomb films, compared with the corresponding nonporous flat films, are more efficient for oxidation of organic molecules via singlet oxygen production at a liquid/solid interface. The oxidations of 1,5-dihydroxynaphthalene to juglone and α-terpinene to ascaridole are followed in ethanol in the presence of both types of films. Oxidation of the organic molecules is a factor 5 greater with honeycomb compared to the nonporous films. This gain is ascribed to two factors: the specific location of the polar photosensitizer at the film interface and the greater exchange surface, as revealed by fluorescence and scanning electron microscopies.