Spectral Manifestation of the Aggregation of Molecules of Octacarboxyphthalocyanine and its Zinc Complex in a Nanoporous
- PDF / 291,550 Bytes
- 6 Pages / 594 x 792 pts Page_size
- 90 Downloads / 138 Views
Journal of Applied Spectroscopy, Vol. 87, No. 4, September, 2020 (Russian Original Vol. 87, No. 4, July–August, 2020)
SPECTRAL MANIFESTATION OF THE AGGREGATION OF MOLECULES OF OCTACARBOXYPHTHALOCYANINE AND ITS ZINC COMPLEX IN A NANOPOROUS SILICATE GEL MATRIX T. A. Pavich,a I. V. Stanishevsky,b D. T. Kozhich,b S. V. Slonskaya,b P. N. Logvinovich,b S. M. Arabei,b* and K. N. Solovyova
UDC 535.37;535.34
The luminescent-spectral properties of molecules of 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine and its zinc complex embedded in nanoporous silicate gel matrices were studied. It was found that H-aggregates of the phthalocyanines are formed at the initial stage of formation of the silicate framework. It was discovered that the monomeric form of the zinc complex in the gel matrix is restored when the silicate material is dried. The reasons for destruction of the aggregates in the restricted volume of the matrix of nanoscale pores are discussed. Keywords: octacarboxyphthalocyanine, zinc complex, sol-gel synthesis, silicate matrix, absorption and fluorescence spectra, monomeric and aggregated forms. Introduction. The range of practical applications of phthalocyanines can be extended by changing their structure — by modifying the benzene fragments of the phthalocyanine ring with functional side substituents and/or by choosing an additional central metal atom that enters into coordination with the phthalocyanine macrocycle (the formation of metal complexes) and also by combining various axial ligands with the central atom. In [1–5] it was shown that the addition of eight COOH groups at the ortho positions of phthalocyanine (the formation of the free base 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine (H2(COOH)8Pc)) significantly increases the solubility of the compounds in water and other solvents. Investigations of octacarbonylphthalocyanines as potential photosensitizers for photodynamic therapy [6, 7] or as agents having high catalytic and photocatalytic activity [5, 8] were motivated by their intense absorption in the phototherapeutic window (600–800 nm) and also by the above-mentioned ability to form aqueous solutions as close as possible to physiological. At the same time an effect undesirable for such applications can arise in the solutions, i.e., the formation of aggregates of the phthalocyanines on account of noncovalent forces of attraction between two or more molecules of the monomer. Photoelectrochemical investigations [9, 10] showed that M(COOH)8Pc in the solid state, adsorbed on the surface of a thin porous film of ZnO, can fulfill the role of photosensitizers in photovoltaic cells. A thin composite film containing layers of Cu(COOH)8Pc and an organic polymer exhibits third-order nonlinearity [11] and can be used in optoelectronics. Investigations of the luminescence spectral characteristics of Zn(COOH)8Pc, deposited on a gold surface in the form of films [12] or covalently bonded to the surface of magnetic nanoparticles of Fe3O4 [13], and also the spectral manifestations of its interaction with amino aci
Data Loading...
