Short-Chained Anthracene Strapped Porphyrins and their Endoperoxides.

The syntheses of short-chained anthracene-strapped porphyrins and their Zn(II)complexes are reported. The key synthetic step is a [2+2] condensation between a dipyrromethane and an anthracene bisaldehyde, 2,2'-((anthracene-9,10-diylbis(methylene))bis(oxy))dibenzaldehyde. Following exposure to white light, self-sensitized singlet oxygen and the anthracene moieties underwent [4+2] cycloaddition reactions to yield the corresponding endoperoxides.

In vitro cytotoxicity of a library of BODIPY-anthracene and -pyrene dyads for application in photodynamic therapy.

The facile synthesis and in vitro activity of a library of heavy atom-free BODIPY-anthracene, -pyrene dyads (BAD-13-BPyrD-19) and a control (BODIPY 20) are reported. We demonstrate that singlet oxygen produced from dyad triplet states formed from charge-separated states is sufficient to induce cytotoxicity in human breast cancer cells (MDA-MB-468) at micromolar concentrations. The compounds in this series are promising candidates for photodynamic therapy, especially BAD-17 which displays significant photocytotoxicity (15% cell viability) at a concentration of 5 × 10-7 M, with minimal toxicity (89% cell viability) in the absence of light.

The good, the bad, and the ugly - controlling singlet oxygen through design of photosensitizers and delivery systems for photodynamic therapy.

Singlet oxygen, although integral to photodynamic therapy, is notoriously uncontrollable, suffers from poor selectivity and has fast decomposition rates in biological media. Across the scientific community, there is a conscious effort to refine singlet oxygen interactions and initiate selective and controlled release to produce a consistent and reproducible therapeutic effect in target tissue. This perspective aims to provide an insight into the contemporary design principles behind photosensitizers and drug delivery systems that depend on a singlet oxygen response or controlled release.

Control of triplet state generation in heavy atom-free BODIPY-anthracene dyads by media polarity and structural factors.

A family of heavy atom-free BODIPY-anthracene dyads (BADs) exhibiting triplet excited state formation from charge-transfer states is reported. Four types of BODIPY scaffolds, different in the alkyl substitution pattern, and four anthracene derivatives have been used to access BADs. Fluorescence and intersystem crossing (ISC) in these dyads depend on donor-acceptor couplings and can be accurately controlled by substitution or media polarity.

Delayed release singlet oxygen sensitizers based on pyridone-appended porphyrins.

A new type of porphyrin photosensitizer capable of generating singlet oxygen upon irradiation, storing it through binding to pyridone subunits, followed by slow release at 20-40 °C, is reported. The timescale of singlet oxygen release can be varied depending on the pyridone group substitution pattern, forming endoperoxides of different stabilities. Modified tetra- and octa-substituted pyridone-porphyrins showed solubility in water, allowing for straightforward delivery into cells.