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Four amine-derivative phenothiazines were converted to the corresponding diazonium salt forms prior to their electrochemical grafting on the GC electrode with the aim to assess their ability to generate singlet oxygen. It was demonstrated by cyclic voltammetry and XPS spectroscopy that the molecular layers were effectively bound to the GC surface by applying the reductive potential in situ in the reaction diazo-mixture. The chosen procedure without the product separation step, appears to be especially useful due to the high solubility of the resulted phenothiazine diazonium salts. The effectiveness of singlet oxygen generation was measured for all of the grafted surfaces by UVVis spectra monitoring of the adjacent solution phase of 1,3-diphenylisobenzofuran (DPBF), which is well known trapping molecule used in detection of singlet oxygen. The data presented in the work prove that all of the molecular layers are effective singlet oxygen generators that might be used for various areas of applications where a highly oxidative reactant is required. [ABSTRACT FROM AUTHOR]

Two highly efficient commercial organic photosensitizers—azure A (AA) and 5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin (APTPP)—were covalently attached to the glass surface to form a photoactive monolayer. The proposed straightforward strategy consists of three steps, i.e., the initial chemical grafting of 3-aminopropyltriethoxysilane (APTES) followed by two chemical postmodification steps. The chemical structure of the resulting mixed monolayer (MIX_TC_APTES@glass) was widely characterized by X-ray photoelectron (XPS) and Raman spectroscopies, while its photoactive properties were investigated in situ by UV–Vis spectroscopy with α-terpinene as a chemical trap. It was shown that both photosensitizers retain their activity toward light-activated generation of reactive oxygen species (ROS) after immobilization on the glassy surface and that the resulting nanolayer shows high stability. Thanks to the complementarity of the spectral properties of AA and APTPP, the effectiveness of the ROS photogeneration under broadband illumination can be optimized. The reported light-activated nanocoating demonstrated promising antimicrobial activity toward Escherichia coli (E. coli), by reducing the number of adhered bacteria compared to the unmodified glass surface. [ABSTRACT FROM AUTHOR]