Novel Silicon Phthalocyanines Bearing Triethylene Glycol Groups: Photophysical and Photochemical Properties as well as pH-Induced Spectral Behaviour

Chemo-photodynamic Activity of Silicon Phthalocyanines Bearing Cyclooxygenase Inhibitors on Colorectal Cancer Cell Lines

Colorectal cancer ranks as the third most lethal cancer worldwide, resulting in over 1 million cases and 900 000 deaths per year. According to population-based studies, administration of long-term non-steroidal anti-inflammatory drugs (NSAIDs) was proven to reduce the risk of a subject developing colorectal cancer. In the present study, the anti-cancer activity of two different NSAIDs, sulindac- (Pc-1) or diclofenac-substituted (Pc-2) asymmetric silicon phthalocyanine derivatives, was evaluated in four different colorectal cancer cell lines bearing various carcinogenic mutations. In this context, the IC₅₀ values of each compound after 24 and 48 h were determined on HCT116, SW480, LoVo, and HT29 cell lines, and the effects of the compounds on programmed cell death pathways apoptosis and autophagy, their impact on cell cycle progression, and the effect of NSAID moieties they bear on COX-1 and COX-2 proteins were analyzed. In addition, the photophysical and photochemical properties of a synthesized Pc derivative bearing axial diclofenac and triethylene glycol groups (Pc-2) have been investigated, and the compound has been characterized by using different analytical techniques. Our results indicated that both compounds inhibit COX protein expression levels, activate apoptosis in all cell lines, and lead to cell cycle arrest in the G2/M phase, depending on the COX expression profiles of the cell lines, indicating that NSAIDs can be coupled with Pc's to achieve increased anti-cancer activity, especially on cancer cells known to have high COX activity.

Silicon phthalocyanines: synthesis and resurgent applications

Their unique axial bonds and NIR optical properties have made silicon phthalocyanines (SiPcs) valuable compounds. Herein, we present key synthetic strategies and emerging applications of SiPcs over the past decade.

Novel axially-substituted silicon phthalocyanines with pH-modulated fluorescence ON/OFF switching properties

Two novel axially-substituted asymmetric silicon (IV) phthalocyanines, the first one substituted with both polyethylene glycol and indomethacin groups (Pc1) and second one substituted with both polyethylene glycol and mefenamic acid groups (Pc2) have been designed and synthesized for the purpose of pH sensing examinations. Their absorption and fluorescence emission-based spectral properties were investigated in chloroform, tetrahydrofuran and toluene. The pH-sensing properties of Pc1 and Pc2 were examined in detail by using UV-vis absorption and fluorescence spectroscopies in tetrahydrofuran. The effects of the substituents on the spectroscopic properties and pH-sensing behavior of these silicon phthalocyanines were revealed. Pc1 didn’t show a pH response; however, Pc2 exhibited a signal increase from pH 5.40 to 0.37 (turn on) and a drastic quenching when pH went from 0.37 to 5.40 (turn off). The protonation/deprotonation stage of the NH group of Pc2 presented fluorescence-based “on-off” type molecular switch properties.

Structural, spectroscopic and passivation properties of a novel binuclear clamshell-type zinc(II) phthalocyanine as gate dielectric for OFET

A novel clamshell-type binuclear zinc(II) phthalocyanine (2) was synthesized by cross condensation of the bisphthalonitrile (1) with 4-tert-butylphthalonitrile and zinc acetate in 1:10:4 ratio. The structure of the novel compound was characterized by elemental analysis, UV-vis, FT-IR (ATR), HR MALDI-TOF mass, [Formula: see text]H NMR, [Formula: see text]C DEPT NMR and [Formula: see text]H–[Formula: see text]H COSY NMR methods. Applying electronic absorption spectroscopy and density functional theory (DFT) revealed that in THF the geometry of 2 is twisted to adopt an intermediate clamshell conformation in which the spacing between the Zn centers is about 8.1Å, providing a very good account of the observed spectrum exhibiting the characteristic B (Soret) band at 347 nm and the Q band at 673 nm. In solution, 2 was found to exist in non-aggregated form. The calculated fluorescence quantum yields ([Formula: see text] 0.23 in THF and 0.10 in DMF) were relatively reduced in comparison to that of std ZnPc. In particular, understanding of leakage current conduction mechanisms in gate dielectrics is crucial for the development of field effect transistors with improved device performance. Analysis of the reverse bias current–voltage data indicated that the origin of leakage current conduction mechanisms in clamshell-type zinc(II) phthalocyanine is Poole-Frenkel emission. The capacitance density of 12.7 nF cm[Formula: see text] at 5 Hz. and 12.1 nF cm[Formula: see text] at 13 MHz was obtained with the FTO/Pc/Au sandwich structure.

Assessment of the relevance of GaPc substituted with azido-polyethylene glycol chains for photodynamic therapy. Design, synthetic strategy, fluorescence, singlet oxygen generation, and pH-dependent spectroscopic behaviour

New synthetic route and PDT potential of symmetrically and asymmetrically substituted Ga(iii)Pcs with terminal azides.