Porphyrin-Polymer as a Photosensitizer Prodrug for Antimicrobial Photodynamic Therapy and Biomolecule Binding Ability.

This study presents the development and characterization of a novel porphyrin-Jeffamine polymer conjugate designed to function as a photosensitizer prodrug for antimicrobial photodynamic therapy (aPDT). The conjugate features a photosensitive porphyrin unit covalently attached to a biocompatible polymer backbone, with enhanced solubility, stability, and bioavailability compared to those of the free porphyrin derivatives. The photophysical properties were studied using transient absorption spectroscopy spanning the fs-μs time scales in addition to emission studies.

Excited-State Dynamics Leading Either to Triplet Formation or Coordinative Expansion following Photolysis of Cu(II)-Porphyrins: A DFT, TD-DFT, Luminescence and Femtosecond Time-Resolved Absorbance Study.

The photophysical properties of Cu(II) complexes with 5,10,15,20--(phenyl)porphyrin and 5,10,15,20--(-methylpyridium-4-yl)porphyrin are examined via the luminescence and femtosecond time-resolved absorbance methods, respectively. These studies are supported by DFT and TD-DFT calculations, which highlight the important role played by ligand-to-metal charge-transfer states in directing the system toward either intersystem crossing to the triplet hypersurface or coordinative expansion to a five-coordinate quasi-stable intermediate. The latter processes occur when the porphyrin is photolyzed in the presence of suitably located Lewis bases.

Controlling Fragmentation of the Acetylene Cation in the Vacuum Ultraviolet via Transient Molecular Alignment.

An open-loop control scheme of molecular fragmentation based on transient molecular alignment combined with single-photon ionization induced by a short-wavelength free electron laser (FEL) is demonstrated for the acetylene cation. Photoelectron spectra are recorded, complementing the ion yield measurements, to demonstrate that such control is the consequence of changes in the electronic response with molecular orientation relative to the ionizing field. We show that stable CH cations are mainly produced when the molecules are parallel or nearly parallel to the FEL polarization, while the hydrogen fragmentation channel (CH → CH + H) predominates when the molecule is perpendicular to that direction, thus allowing one to distinguish between the two photochemical processes.

The Effect of Confinement Angle on Self-Colliding Aluminium Laser Plasmas Using Spectrally Resolved Fast Imaging.

In this work we investigate the effect of the confinement angle on self-colliding aluminium laser produced plasmas. More specifically, we apply V-shaped channel targets of different angles (90°, 60° and 30°) and report both broadband and filtered time-resolved fast imaging measurements on the formation of such plasmas in ambient air. Based on the broadband measurements we suggest that the plasmas formed on the two inner walls of the V-shaped channel expand normally to the surface, interact with each other and possibly stagnate.