Comparative photodynamic inactivation of bioluminescent E. coli by pyridinium and inverted pyridinium chlorins

Photodynamic inactivation (PDI) is a therapeutic approach in study due to the ability to reduce or completely eliminate the bacterial strains without the development of resistance mechanisms. In this therapeutic methodology the cationic chlorins (Chls) with pyridinium or inverted pyridinium moieties are one of the photosensitizers exploited in our biological approaches. In this context, we synthesized and characterized new free-base and zinc(II) complexes of pyridinium or inverted pyridinium Chl derivatives (1b, 2, 2a and 2b, respectively) for the inactivation of Escherichia coli (E. coli). The PDI assay was performed with white light irradiation delivered at a fluence rate of 25 mW cm−2. The obtained results of this study demonstrate high PDI efficiency of the zinc(II) metallated Chl 1b, reaching the detection limit of the bioluminescent method (5.2 log reduction) in 45 min of irradiation.publishe

Influence of the meso-substituents of zinc porphyrins in dye-sensitized solar cell efficiency with improved performance under short periods of white light illumination

The sensitization activity of four zinc metalloporphyrin dyes: meso-tetrakis(4-pyridyl)porphyrinato Zn(II) (a), meso-triphenyl-(4-carboxyphenyl)porphyrinato Zn(II) (b), meso-tetrakis(4-carboxyphenyl)porphyrinato Zn(II) (c) and meso-tripyridyl(4-carboxyphenyl)porphyrinato Zn(II) (d) is reported here, in terms of current-potential curve, open-circuit potential, fill factor, and overall solar energy conversion efficiency which have been evaluated under 100 mW/cm2 light intensity and their performances compared to the benchmark N719 (di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato) ruthenium(II)). This work focus the structural aspects of dyes with anchoring groups using TiO2-based Dye Sensitized Solar Cells (DSSCs), which includes pyridyl and carboxyphenyl acid groups and argue how the combination of both anchoring groups, in the same structure, may allow relevant optimization of DSSCs performance in the near future. Also, a noticeable improvement in the photovoltaic performance of all dyes, reaching a maximum increase from 25% to 69% in the overall DSSC efficiency under short periods of white light illumination is discussed.publishe