Polymer catalysts for important photoelectron transfer reactions

Abstract

Photozymes are novel water-soluble polymers made by the copolymerization of mixtures of hydrophobic and hydrophilic monomers, some of which contain chromophores capable of absorbing light and transmitting the excitation energy to selected traps by means of the antenna effect. The interactions between these groups and water force the polymer to adopt a hypercoiled conformation with hydrophobic pockets similar to those in the catalytic sites of natural enzymes. Hydrophobic organic compounds in the water solution will seek out and localize themselves in these regions, where they are subjected to electronic energy transfer from the light-excited antenna chromophores. The chemical reactions which occur are often different and more specific than in the case of photoreactions in common organic solvents. In a number of cases the reactions appear to proceed by an electron transfer mechanism. This paper summarizes recent results on the dechlorination of chlorinated aromatic and aliphatic compounds, and laser studies of multiphoton processes in aromatic compounds such as 9-(acetoxymethy1)phenanthrene (AMP).

Layer-by-layer coating of photoactive polymers for biomedical applications

“…Photozymes are amphiphilic photoactive polymers, composed by fluorophore units such as xanthene dyes (fluorescein, rose bengal, eosin, eritrosin), naphthalene, carbazole, and hydrophilic units, containing strong electrolytes such as sulphonate groups or weak electrolytes such as the primary amino groups of chitosan chains [5][6][7]. Photozymes may be statistical, block or graft copolymers and they are generally water soluble.…”

Biomimetic Tailoring of the Surface Properties of Polymers at the Nanoscale: Medical Applications

“…Aromatic chromophores undergo strong interactions, which induce the coiling of the macromolecules and the formation of hydrophobic domains surrounded by charged fragments of the chains. The hydrophobic packed domains may solubilize hydrophobic guest molecules and play the role of nanoreactors with photochemical activity [106]. Among photozymes, chitosan-fluorescein (CH-FL) has been demonstrated to be photo-bioactive: the classical biomimetic approach has been found to be successful only by proper excitation of its chromophoric groups [103].…”

“…Photozymes are amphiphilic photoactive polymers, having fluorophores such as xanthene dyes (fluorescein, rose bengal, eosin, eritrosin), naphthalene, carbazole, and hydrophilic units, containing strong electrolytes such as sulphonate groups or weak electrolytes such as the primary amino groups of chitosan chains [104][105][106]. Photozymes may be statistical, block, or graft copolymers and they are generally water soluble.…”

Environmentally friendly photosensitizer: starch modified with chlorophyll‐type chromophores

“…Hydrophobic groups are usually constructed from photoactive chromophores, which are able to absorb light from the UV‐visible spectral region. The term antenna indicates that the energy absorbed can migrate among the chromophores attached to the polymeric chain and be transferred to the molecules solubilized in hydrophobic polymeric microdomains, thus inducing their photochemical conversion 6. Such an antenna effect is used for efficient light harvesting in photosynthetic systems of plants.…”

“…Such an antenna effect is used for efficient light harvesting in photosynthetic systems of plants. Mimicking these natural systems directed us to the synthesis of artificial antenna polymers that could be applied both to photosynthesis of useful compounds7 and photodegradation of harmful pollutants 6, 8…”