Supramolecular Control of Singlet Oxygen Generation

Abstract

Singlet oxygen (1O2) is the excited state electronic isomer and a reactive form of molecular oxygen, which is most efficiently produced through the photosensitized excitation of ambient triplet oxygen. Photochemical singlet oxygen generation (SOG) has received tremendous attention historically, both for its practical application as well as for the fundamental aspects of its reactivity. Applications of singlet oxygen in medicine, wastewater treatment, microbial disinfection, and synthetic chemistry are the direct results of active past research into this reaction. Such advancements were achieved through design factors focused predominantly on the photosensitizer (PS), whose photoactivity is relegated to self-regulated structure and energetics in ground and excited states. However, the relatively new supramolecular approach of dictating molecular structure through non-bonding interactions has allowed photochemists to render otherwise inactive or less effective PSs as efficient 1O2 generators. This concise and first of its kind review aims to compile progress in SOG research achieved through supramolecular photochemistry in an effort to serve as a reference for future research in this direction. The aim of this review is to highlight the value in the supramolecular photochemistry approach to tapping the unexploited technological potential within this historic reaction.

Noncovalent Interactions with PAMAM and PPI Dendrimers Promote the Cellular Uptake and Photodynamic Activity of Rose Bengal: The Role of the Dendrimer Structure

“…At the same time, free dendrimers did not generate singlet oxygen. A similar effect was previously observed for supramolecular complexes of PSs and various polymers, 55 including RB and cationic dendrimers. 16 On the other hand, no increase in singlet oxygen production was observed in the case of RB complexed with anionic half-generation PAMAM dendrimers; 17 for PEG2000-modified PPI and PAMAM G4 dendrimers, the singlet oxygen level was reduced upon encapsulation of RB.…”

Nonionic omnisoluble photosensitizer reference material for the estimation of singlet oxygen quantum yield

“…Chromophores possessing electronic structures that allow access to triplet excited states are capable of interacting with molecular oxygen, whose ground state is also a triplet, leading to the generation of singlet oxygen ( 1 O 2 ). 1,2 1 O 2 is a reactive oxygen species (ROS) often considered deleterious but which is gaining increasing recognition for its positive uses including in organic synthesis, 3 for elimination of pollutants 4 ( e.g. , for water purification 5 ) and more importantly for photodynamic therapies (PDT) 6 involving cancer treatment 7 or microbial inactivation.…”

Reactive oxygen species on transition metal-based catalysts for sustainable environmental applications

“…Many studies use 1 O 2 as an environmentally benign, versatile, and moderate ROS for the selective oxidation of organic substances, 169,280 as 1 O 2 shows high affinity for organic substrates with electron-rich moieties (e.g., olens, suldes, and amines). 281,282 Chen et al developed a metal-organic framework based on Pt nanocrystals and porphyrin, denoted as Pt/PCN-224(M), to selectively oxidize aromatic alcohols to the corresponding aldehydes with O 2 (Fig. 19a).…”