Zn(II)-tetracarboxy-phthalocyanine-Sensitized TiO2 Thin Films as Antimicrobial Agents under Visible Irradiation: a Combined DFT and Experimental Study

In this article, we studied the antimicrobial activity of TiO2 sensitized by the Zn(II)-tetracarboxy-phthalocyanine (TcPcZn) complex using TiO2-Degussa P25 as a semiconductor source. The TiO2 thin films were deposited by the doctor blade method and were sensitized by the chemisorption process. The obtained compounds were characterized using Fourier transform infrared spectroscopy, UV-vis spectrophotometry, Raman spectroscopy, diffuse reflectance spectroscopy, and scanning electron microscopy. Furthermore, we studied the stability of the adsorbed sensitizer on the semiconductor surface by using the density functional theory (DFT). Additionally, we determined the antimicrobial activity of TcPcZn-TiO2 against methicillin-resistant Staphylococcus aureus (MRSA). The Raman and optical results confirmed the sensitizing process. The TcPcZn-TiO2 thin films showed radiation absorption in the visible range of the electromagnetic spectrum (600-750 nm), and the dye anchored on the TiO2 surface had a band gap of 1.58 eV. The DFT study showed that TcPcZn supported on any phase of Degussa P25 is stable, making them suitable to act as catalysts in the proposed reactions. Finally, the TcPcZn-TiO2 thin films reached 76.5% of inhibition activity against MRSA.

The heavy atom effect on Zn(ii) phthalocyanine derivatives: a theoretical exploration of the photophysical properties

Absorption electronic spectra, singlet-triplet energy gaps and spin-orbit matrix elements have been computed at DFT and TDDFT levels of theory for a series of substituted Zn(ii)-phthalocyanines (ZnPcs), recently proposed as potential photosensitizers in photodynamic therapy (PDT). Their photophysical properties have been rationalized in the light of the substitution pattern which includes the position, the donor or withdrawing nature, and the relative donating force of peripheral and non-peripheral ligands. Moreover, the effects of heavy substituents on these properties have been investigated by introducing a different number of iodine atoms on the phthalocyanine macrocycle. The results show that the substitution pattern significantly affects the absorption spectra, but just slightly modifies the ΔES-T values. The presence of heavy atoms produces a significant effect on the photophysical properties of the investigated compounds enhancing the spin-orbit coupling (SOC) values.

Synthesis and characterization of a sulfur-containing phthalocyanine-gold nanoparticle hybrid

This work reports on the synthesis and characterization of a new gold nanoparticle-zinc phthalocyanine system, AuNP - S (t Bu )3 ZnPc , prepared by a ligand exchange reaction of tetraoctylammonium bromide with a novel unsymmetrically substituted zinc phthalocyanine which contains one thioester group in the peripheral position [ AcS (t Bu )3 ZnPc ]. The AuNP - S (t Bu )3 ZnPc hybrid was characterized using UV-vis and 1 H NMR spectroscopies. Transmission electron microscopy allowed the estimation of the size, which was calculated to be ~5 nm. AuNPs - S (t Bu )3 ZnPc conjugate showed much lower fluorescence quantum yield values than the AcS (t Bu )3 ZnPc demonstrating either an energy or electron transfer from the ZnPc to the AuNP . The AuNP - S (t Bu )3 ZnPc hybrid has been anchored to a TiO 2 semiconducting layer using lipoic acid. A solid configuration of TiO 2-lipoic acid- AuNP - S (t Bu )3 ZnPc has been prepared by anchoring lipoic acid to the TiO 2 ( TiO 2-LA) and introducing later the TiO 2-LA with free thiol groups in a toluene solution of AuNP - S (t Bu )3 ZnPc . We have also observed by UV-vis and fluorescence measurements the importance of the ZnPc in avoiding AuNP aggregation on the TiO 2 surface.