A time-resolved spectroscopic investigation of a novel BODIPY copolymer and its potential use as a photosensitiser for hydrogen evolution

A novel 4,4-difuoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) copolymer with diethynylbenzene has been synthesised, and its ability to act as a photosensitiser for the photocatalytic generation of hydrogen was investigated by time-resolved spectroscopic techniques spanning the ps- to ns-timescales. Both transient absorption and time-resolved infrared spectroscopy were used to probe the excited state dynamics of this photosensitising unit in a variety of solvents. These studies indicated how environmental factors can influence the photophysics of the BODIPY polymer. A homogeneous photocatalytic hydrogen evolution system has been developed using the BODIPY copolymer and cobaloxime which provides hydrogen evolution rates of 319 μmol h−1 g−1 after 24 h of visible irradiation

Exploiting a neutral BODIPY copolymer as an effective agent for photodynamic antimicrobial inactivation.

We report the synthesis and photophysical properties of a neutral BODIPY photosensitizing copolymer (poly-8-(4-hydroxymethylphenyl)-4,4-difluoro-2,6-diethynyl-4-bora- 3a,4a-diaza-s-indacene) containing ethynylbenzene links between the BODIPY units. The copolymer absorbs further towards the red in the UV-vis spectrum compared to the BODIPY precursor. Photolysis of the polymer produces a singlet excited state which crosses to the triplet surface in less than 300 ps. This triplet state was used to form singlet oxygen with a quantum yield of 0.34. The steps leading to population of the triplet state were studied using time-resolved spectroscopic techniques spanning the pico- to nanosecond timescales. The ability of the BODIPY polymer to generate a biocidal species for bactericidal activity in both solution- and coating-based studies was assessed. When the BODIPY copolymer was dropcast onto a surface, 4 log and 6 log reductions in colony forming units/ml representative of Gram-positive and Gramnegative bacteria, respectively, under illumination at 525 nm were observed. The potent broadspectrum antimicrobial activity of a neutral metal-free copolymer when exposed to visible light conditions may have potential clinical applications in infection management