Synthesis of axially disubstituted silicon(IV) phthalocyanines and investigation of their photophysical and photochemical properties

In this study, the axially 1-(4-(3-(6-hydroxyhexyl)-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)piperazin-1-yflethanone and 1-(4-(3-(2-(2-hydroxyethoxy)ethyl)-3,4-dihydro-2H-benzo[e][1,3]oxazin-6-yl)piperazin-1-yflethanone disubstituted silicon(IV) phthalocyanines and their corresponding quaternized derivatives were synthesized for the first time as candidate photosensitizers for photodynamic therapy (PDT) in cancer treatment. The structures of these novel compounds were confirmed by some spectroscopic techniques such as FT-IR, H-1 NMR, C-13 NMR, UV-Vis, and mass. The axially substitution increased the solubility of the silicon(IV) phthalocyanines. The prepared silicon(IV) phthalocyanines showed great results achieved from photochemical and photophysical investigations in DMSO solution. Especially, high singlet oxygen (Phi(Delta)) and the fluorescence quantum yield (Phi(F)) values of the quaternized silicon (IV) phthalocyanines indicates that these compounds have major potential as photosensitizers in PDT. Furthermore, studied silicon(IV) phthalo-cyanine complexes could be classified as the stable photosensitizer in accordance with photodegradation study results. The fluorescence quenching behavior of these phthalocyanine complexes was also examined using fluorescence quenching method by 1,4-benzoquinone (BQ).