Novel axially carborane-cage substituted silicon phthalocyanine photosensitizer; synthesis, characterization and photophysicochemical properties

Enhancing antitumor efficacy of NIR-I region zinc phthalocyanine@upconversion nanoparticle through lysosomal escape and mitochondria targeting

Accurately visualizing the intracellular trafficking of upconversion nanoparticles (UCNPs) loaded with phthalocyanines and achieving precise photodynamic therapy (PDT) using near-infrared (NIR) laser irradiation still present challenges. In this study, a novel NIR laser-triggered upconversion luminescence (UCL) imaging-guided nanoparticle called FA@TPA-NH-ZnPc@UCNPs (FTU) was developed for PDT. FTU consisted of UCNPs, folic acid (FA), and triphenylamino-phenylaniline zinc phthalocyanine (TPA-NH-ZnPc). Notably, TPA-NH-ZnPc showcases aggregation-induced emission (AIE) characteristic and NIR absorption properties at 741 nm, synthesized initially via molybdenum-catalyzed condensation reaction. The UCL emitted by FTU enable real-time visualization of their subcellular localization and intracellular trafficking within ovarian cancer HO-8910 cells. Fluorescence images revealed that FTU managed to escape from lysosomes due to the "proton sponge" effect of TPA-NH-ZnPc. The FA ligands on the surface of FTU further directed their transport and accumulation within mitochondria. When excited by a 980 nm laser, FTU exhibited UCL and activated TPA-NH-ZnPc, consequently generating cytotoxic singlet oxygen (1O2), disrupted mitochondrial function and induced apoptosis in cancer cells, which demonstrated great potential for tumor ablation.

Monitoring of singlet oxygen generation of a novel Schiff-base substituted silicon phthalocyanines by sono-photochemical studies and in vitro activities on prostate cancer cell

This study demonstrates the potential of sono-photodynamic therapy as an effective approach for enhancing singlet oxygen generation using the synthesized Schiff-base diaxially substituted silicon phthalocyanines. In photochemical studies, the singlet oxygen quantum yields (Φ∆) were determined as 0.43 for Si1a, 0.94 for Q-Si1a, 0.58 for S-Si1a, and 0.49 for B-Sia1. In sono-photochemical studies, the Φ∆ values were reached to 0.67 for Si1a, 1.06 for Q-Si1a, 0.65 for S-Si1a, and 0.67 for B-Sia1. In addition, this study demonstrates the therapeutic efficacy of phthalocyanines synthesized as sensitizers on the PC3 prostate cancer cell line through in vitro experiments. The application of these treatment modalities exhibited notable outcomes, leading to a substantial decrease in cell viability within the PC3 prostate cancer cell line. These findings highlight the potential of utilizing these synthesized phthalocyanines as promising therapeutic agents for prostate cancer treatment.

Dual effect of light and ultrasound for efficient singlet oxygen generation with novel diaxial silicon phthalocyanine sensitizer

To treat a life-threatening disease like cancer, photodynamic therapy (PDT) and sonodynamic therapy (SDT) methods were combined into sono-photodynamic therapy (SPDT) as an effective therapeutic solution. Each day, the usage of phthalocyanine sensitizers increases in the therapeutic applications as they have the ability to produce more reactive oxygen species. In this context, a new diaxially silicon phthalocyanine sensitizer, containing triazole and tert-butyl groups, was synthesized. After elucidating the structure of the complex with elemental analysis, FT-IR, UV-Vis, MALDI-TOF MS and 1 H NMR, its photophysical, photochemical and sono-photochemical properties were examined. When singlet oxygen generation capacity of the new synthesized silicon phthalocyanine complex was determined and compared among photochemical (PDT; ФΔ  = 0.59 in DMSO, 0.44 in THF, 0.47 in toluene) and sonophotochemical (SPDT; ФΔ  = 0.88 in dimethyl sulfoxide (DMSO), 0.60 in tetrahydrofuran (THF), 0.65 in toluene) methods, it can be said that the complex is a successful sono-photosensitizer that can be used as a good SPDT agent in vitro or in vivo future studies.

Comparing Singlet Oxygen Generation of Schiff Base Substituted Novel Silicon Phthalocyanines by Sonophotochemical and Photochemical Applications

Although the sonophotodynamic method has an effective therapeutic outcome for anticancer treatment compared with the photodynamic method, there are not enough related studies in the literature and this study aims to contribute to the development of sonophotodynamic studies. For this purpose, the Schiff base substituted silicon phthalocyanines were designed and synthesized as effective sensitizer candidates and the photophysicochemical and sonophotochemical features of the phthalocyanines were examined to increase singlet oxygen efficiency. The calculated ΦΔ values indicate that the contribution of substituent groups improved the production of singlet oxygen compared with silicon (IV) phthalocyanine dichloride (SiPcCI2 ) and also the sonophotochemical applications increased the singlet oxygen yields. The ΦΔ values (ΦΔ  = 0.76 for axially bis-{4-[(E)-(pyridin-3-ylimino)methyl]phenol} substituted silicon (IV) phthalocyanine (2a), 0.68 for axially bis-4-[(E)-{[(pyridin-3-yl)methyl]imino}methyl]phenol substituted silicon (IV) phthalocyanine (2b) in photochemical study) reached to ΦΔ  = 0.98 for 2a, 0.94 for 2b in sonophotochemical study. This article will enrich the literature on increasing singlet oxygen yield.

Arginine mediated photodynamic therapy with silicon(IV) phthalocyanine photosensitizers

In the current study, we synthesized a new SiPc derivative conjugated with arginine at the axial positions, for a novel phthalocyanine-based photosensitizer for photodynamic therapy (PDT) applications in cancer cells. Axially-di-arginine substituted new silicon(IV) phthalocyanine photosensitizer (PS-5a) has been thoroughly researched for its anti-cancer properties. Various spectroscopic techniques were used to characterize this conjugate, including 1H NMR, 13C NMR, FT-IR, UV-vis, and MS spectral data. The in vitro PDT activities of the conjugate on cancer cells were tested through its cytotoxic, clonogenic, apoptotic effects on, and its capacity to induce DNA damage, and the disruption of mitochondrial membrane potential in cancer cell lines (liver; HuH-7, cervix; HeLa and breast; MCF7). Cancer cells exposed to the light illumination following uptake of the PS-5a as a photosensitizer revealed DNA breakage and collapsed mitochondrial membrane potential. The results of the present investigation demonstrate that PS-5a has a significant photo-cytotoxic effect on cancer cells. So, axially-di-arginine substituted silicon(IV) phthalocyanine could be an effective PDT agent for PDT treatment.

Silicon(IV) complexes of octaaryl-substituted porphyrazines and corrolazines: influence of macrocycle contraction on spectral-luminescence, acid-base, and redox properties

The template cyclomerization of the iminoimide derivatives (obtained by the treatment of diarylfumarodinitriles with NH₃ in methanol containing catalytic amounts of dissolved Na) in the presence of SiCl₄ in pyridine leads to silicon(IV) octaarylporphyrazine complexes ((HO)₂SiPzAr₈, Ar = Ph, ^tBuPh) as a main reaction product. In the case of phenyl-substituted derivative, the formation of a distinctive Si(IV) complex as a byproduct was observed, which according to mass-spectroscopy measurement contains the macrocycle with five diphenylpyrrolic units. The treatment of bishydroxy complexes with tripropylchlorosilane in the presence of magnesium in pyridine leads to the formation of axially siloxylated porphyrazines (Pr₃SiO)₂SiPzAr₈, followed by the reductive contraction of the macrocycle and formation of the corresponding corrolazine complexes (Pr₃SiO)SiCzAr₈. It is shown that the addition of acid (trifluoroacetic acid, TFA) facilitates the detachment of one siloxy group in (Pr₃SiO)₂SiPzAr₈ and is essential for its Pz → Cz transformation. In the presence of TFA, only one meso-nitrogen is protonated in the porphyrazine complexes (Pr₃SiO)₂SiPzAr₈ (stability constant of the protonated form pK_s1 = -0.45 for Ar = Ph; pK_s1 = 0.68 for Ar = ^tBuPh), while two consequent protonation stages are observed for the more basic corrolazine complex (Pr₃SiO)SiCzPh₈ (pK_s1 = 0.93, pK_s2 = 0.45). Both types of Si(IV) complexes are poorly fluorescent (Φ_F < 0.07). The porphyrazine complexes have low ability to generate singlet oxygen (Φ_Δ < 0.15), whereas the corrolazine derivative (Pr₃SiO)SiCzPh₈ is a very efficient photosensitizer (Φ_Δ = 0.76).

Comparison of sonodynamic, photodynamic and sonophotodynamic therapy activity of fluorinated pyridine substituted silicon phthalocyanines on PC3 prostate cancer cell line

BACKGROUND

Sonophotodynamic therapy (SPDT), a combination of photodynamic therapy (PDT) and sonodynamic therapy (SDT), may offer theraputic advantage. The therapeutic effects of sonodynamic, photodynamic, and sonophotodynamic of 5-(trifluoromethyl)-2-thiopyridine substituted silicon phthalocyanine (gy3) and its quaternized derivative (gy3q) were examined in vitro on prostate cancer using PC3 cells.

METHODS

The SDT, PDT and SPDT efficiency was determined by using MTT test.Apoptosis mechanism was evaluated by HOPI staining.

RESULTS AND DISCUSSIONS

According to MTT results, the phthalocyanines decreased cell viability when compared with a control group. Also, apoptosis measurement data represents that the phthalocyanines would produce much better therapeutic outcomes compare to PDT and SDT by utilizing SPDT. Further studies should be performed to understand the effectiveness of SPDT.

A hypoxia responsive silicon phthalocyanine containing naphthquinone axial ligands for photodynamic therapy activity

A liposome loaded‑silicon (IV) phthalocyanine (SiPc) containing naphthoquinone axial ligands as hypoxia-responsive a prodrug-like moieties (Prodrug-SiPc), is herein reported. With the help of computational methods, this study assessed the photophysical, photochemical and electrochemical redox properties of the Prodrug-SiPc to elucidate the relationship between material structure and properties. The attachment of the axial quinoid moieties endowed the Prodrug-SiPc with Type I/II photochemical and prodrug-like properties. Following liposomal encapsulation, the therapeutic efficacy of Prodrug-SiPc-liposomes was investigated against Michigan Cancer Foundation-7 (MCF-7) and Henrietta Lacks (Hela) cancer cells as in vitro cancer models and revealed that the as-synthesized Prodrug-SiPc-liposomes are potential photodynamic therapy (PDT) drug candidates. The Prodrug-SiPc-liposome takes full advantage of the hypoxic microenvironment of tumors - a side effect PDT - to trigger therapy, resulting in significantly enhanced efficacy compared to typical PDT. This work highlights the importance of multiple characteristics in designing new and effective photosensitizer candidates.

Ru(ii) and Ir(iii) phenanthroline-based photosensitisers bearing o-carborane: PDT agents with boron carriers for potential BNCT

Four novel transition metal-carborane photosensitisers were prepared by Sonogashira cross-coupling of 1-(4-ethynylbenzyl)-2-methyl-o-carborane (A-CB) with halogenated Ru(ii)- or Ir(iii)-phenanthroline complexes. The resulting boron-rich complexes with one (RuCB and IrCB) or two carborane cages (RuCB2 and IrCB2) were spectroscopically characterised, and their photophysical properties investigated. RuCB displayed the most attractive photophysical properties in solution (λ_em 635 nm, τ_T 2.53 μs, and φ_p 20.4%). Nanosecond time-resolved transient absorption studies were used to explore the ³MLCT nature of the triplet excited states, and the highest singlet oxygen quantum yields (Φ_Δ) were obtained for the mono-carborane-phenanthroline complexes (RuCB: 52% and IrCB: 25%). None of the complexes produce dark toxicity in SKBR-3 cells after incubation under photodynamic therapy (PDT) conditions. Remarkably, mono-carboranes RuCB and IrCB were the best internalised by the SKBR-3 cells, demonstrating the first examples of tris-bidentate transition metal-carborane complexes acting as triplet photosensitisers for PDT with a high photoactivity; RuCB or IrCB killed ∼50% of SKBR-3 cells at 10 μM after irradiation. Therefore, the high-boron content and the photoactive properties of these photosensitisers make them potential candidates as dual anti-cancer agents for PDT and Boron Neutron Capture Therapy (BNCT).

Synthesis and photodynamic activities of novel silicon(iv) phthalocyanines axially substituted with water soluble groups against HeLa cancer cell line

In this study, compounds 1 and 2, and their silicon(iv) phthalocyanine (SiPc) derivatives 3 and 4, which bear these ligands as substituents on the axial positions were synthesized. These SiPcs (3 and 4) were also converted to their water soluble derivatives (3a and 4a). All these novel compounds were fully characterized by a combination of spectroscopic data such as FT-IR, ¹H-NMR, ¹³C-NMR and UV-vis as well as mass spectroscopy. The photophysicochemical properties (fluorescence quantum yields and lifetimes, singlet oxygen, and photodegradation quantum yields) were investigated in DMSO for all the studied SiPcs (3 and 4) and in both DMSO and aqueous solutions for the water soluble SiPcs (3a and 4a). Effects of quaternization of these phthalocyanines on photophysicochemical properties were also determined. The photodynamic therapy activities of the water soluble SiPcs (3a and 4a) were tested against to the HeLa cancer cell lines and these phthalocyanines exhibited cytotoxicity against these cell lines.

Experimental and theoretical investigation of water-soluble silicon(IV) phthalocyanine and its interaction with bovine serum albumin

Photodynamic therapy (PDT) has drawn a great scientific attention to cancer treatment over the last decades. However, the bottleneck for the PDT is to find good photosensitizers (PSs) with greater water solubility, no aggregation, and fast discharge from the body. Therefore, there are still a big scientific desire for the synthesizing new rational PSs for treatment of cancer by PDT technique. In favor of improving the competence of PDT, an axially bis[4-(diphenylamino-1,1'-biphenyl-4-ol)] substituted silicon(IV) phthalocyanine (3) was converted to its water-soluble quaternized derivative (3Q). Their structures were fully characterized by single-crystal X-ray diffraction, elemental analysis, and different spectroscopic methods such as FT-IR, UV-Vis, MALDI-TOF, and ¹H-NMR. The photophysical properties such as fluorescence quantum yields and lifetimes, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated. Ground and excited-state calculations were performed to explain the observed electronic absorption spectra. The addition of the 4-diphenylamino-1,1'-biphenyl-4-ol groups on the axially positions of the silicon(IV) phthalocyanine increased the singlet oxygen quantum yield from 0.15 to around 0.20. Especially quaternized compound 3Q showed high singlet oxygen quantum yield of 0.26 in water solution. In addition, a spectroscopic investigation of the binding behavior of the quaternized silicon (IV) phthalocyanine complex to bovine serum albumin (BSA) is also studied in this work, confirming the possible interaction. Further theoretical calculations were carried out to find out the plausible-binding regions of the BSA protein. Axially bis[4-(diphenylamino-1,1'-biphenyl-4-ol)] substituted silicon(IV) phthalocyanine (3) was converted to its quaternized water soluble derivative (3Q). The photophysical properties such as fluorescence quantum yields and lifetimes, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated. In addition, a spectroscopic investigation of the binding behavior of the quaternized silicon (IV) phthalocyanine complex to bovine serum albumin (BSA) is also studied in this work, confirming the possible interaction. Further theoretical calculations were carried out to find out the plausible binding regions of the BSA protein.

Reversibly Switchable Fluorescent Molecular Systems Based on Metallacarborane-Perylenediimide Conjugates

Icosahedral metallacarboranes are θ-shaped anionic molecules in which two icosahedra share one vertex that is a metal center. The most remarkable of these compounds is the anionic cobalt-based metallacarborane [Co(C₂ B₉ H₁₁ )₂ ]^- , whose oxidation-reduction processes occur via an outer sphere electron process. This, along with its low density negative charge, makes [Co(C₂ B₉ H₁₁ )₂ ]^- very appealing to participate in electron-transfer processes. In this work, [Co(C₂ B₉ H₁₁ )₂ ]^- is tethered to a perylenediimide dye to produce the first examples of switchable luminescent molecules and materials based on metallacarboranes. In particular, the electronic communication of [Co(C₂ B₉ H₁₁ )₂ ]^- with the appended chromophore unit in these compounds can be regulated upon application of redox stimuli, which allows the reversible modulation of the emitted fluorescence. As such, they behave as electrochemically-controlled fluorescent molecular switches in solution, which surpass the performance of previous systems based on conjugates of perylendiimides with ferrocene. Remarkably, they can form gels by treatment with appropriate mixtures of organic solvents, which result from the self-assembly of the cobaltabisdicarbollide-perylendiimide conjugates into 1D nanostructures. The interplay between dye π-stacking and metallacarborane electronic and steric interactions ultimately governs the supramolecular arrangement in these materials, which for one of the compounds prepared allows preserving the luminescent behavior in the gel state.

Synthesis of new water soluble silicon phthalocyanine substituted by linker sulfur atom and photophysicochemical studies for photodynamic therapy

In this work, 5-(trifluoromethyl)-2-thiopyridine substituted SiPc (1) and its quaternized derivative (2) were synthesized, and the effect of the linker sulfur atom on silicon phthalocyanines has been investigated for the first time in the literature. Both of the complexes have been characterized by standard spectroscopy methods. The complexes have good solubility in organic solvents and showed monomeric tendencies in all studied solvents. Only complex 2 had some aggregation in water because of solvent effects, as expected. In order to determine the therapeutic effect for cancer treatment, photophysicochemical properties were investigated in DMSO, DMF, toluene and water (for complex 2). The synthesized complexes were found to have about 3.5 times higher singlet oxygen quantum yields than the yields of unsubstituted SiPcCl2 ([Formula: see text] = 0.15 (in DMSO), 0.12 (in DMF), 0.10 (in toluene)) because of the effects of bulky axial groups.

New peripherally substituted lutetium mono and bis phthalocyanines: Synthesis and comparative photophysical and photochemical properties

In this study, the synthesis and characterization of mono-(phthalocyaninato) lutetium(III) (1-Cl and 1-F) [Lu[Formula: see text](AcO)(Pc)] (Pc [Formula: see text] phthalocyaninato, AcO [Formula: see text] acetate) and bis-(phthalocyaninato) lutetium(III) (2-Cl and 2-Br) [Lu[Formula: see text]Pc[Formula: see text]] bearing halogenated (F, Cl and Br) phenoxy–phenoxy groups are described and verified by IR, [Formula: see text]H-NMR, UV-vis and mass spectrometry. Photochemical and photophysical properties of 1-F, 1-Cl 2-Cl and 2-Br in DMSO are also presented. A comparison between photophysical and photochemical parameters of mono and bis derivatives showed that mono phthalocyanines are better photosensitizers than bis phthalocyanines. Photophysical and photochemical properties of phthalocyanines are very useful for photodynamic therapy applications. Singlet oxygen quantum yields [Formula: see text] give an indication of the potential of the complexes as photosensitizers in photodynamic therapy applications. The chloro, fluoro, bromo-phenoxy–phenoxy substituted mono-(phthalocyaninato) lutetium(III) complexes (1-Cl and 1-F) gave good singlet oxygen quantum yields (from 0.86 to 0.80) in DMSO. Thus, these complexes show potential as Type II photosensitizers for PDT of cancer.

Phthalocyanines with bromobenzenesulfanyl substituents at non-peripheral position: Preparation, photophysical and photochemical properties

Electron-donating bromobenzenesulfanyl-group-substituted phthalonitrile derivative (1) and its novel non-peripherally tetra-substituted metal-free, indium and zinc phthalocyanine complexes (2–4) have been prepared for the first time. The chemical structures of this new phthalonitrile and its phthalocyanine derivatives were characterized by UV-vis, FT-IR, NMR, and MALDI-TOF mass spectrometry. The introduction of this electron-donating sulfanyl type of non-peripheral substituent accounts for a remarkable red shift of the phthalocyanine Q band to approximately 730 nm. Photophysical and photochemical properties of the novel functional complexes were also examined as photosensitizers for PDT applications.

Porphyrinoid-based photosensitizers for diagnostic and therapeutic applications: An update

Porphyrin-based molecules are actively studied as dual function theranostics: fluorescence-based imaging for diagnostics and fluorescence-guided therapeutic treatment of cancers. The intrinsic fluorescent and photodynamic properties of the bimodal molecules allows for these theranostic approaches. Several porphyrinoids bearing both hydrophilic and/or hydrophobic units at their periphery have been developed for the aforementioned applications, but better tumor selectivity and high efficacy to destroy tumor cells is always a key setback for their use. Another issue related to their effective clinical use is that, most of these chromophores form aggregates under physiological conditions. Nanomaterials that are known to possess incredible properties that cannot be achieved from their bulk systems can serve as carriers for these chromophores. Porphyrinoids, when conjugated with nanomaterials, can be enabled to perform as multifunctional nanomedicine devices. The integrated properties of these porphyrinoid-nanomaterial conjugated systems make them useful for selective drug delivery, theranostic capabilities, and multimodal bioimaging. This review highlights the use of porphyrins, chlorins, bacteriochlorins, phthalocyanines and naphthalocyanines as well as their multifunctional nanodevices in various biomedical theranostic platforms.

Photophysical and photochemical properties of newly synthesized zinc(II) and chloroindium(III) phthalocyanines substituted with 3,5-bis (trifluoromethyl)phenoxy groups

4,5-bis(3,5-bis(trifluoromethyl)phenoxy)phthalonitrile (1) and its complexes, namely 2,3,9,10,16,17,23,24-octakis[3,5-bis(trifluoromethyl)phenoxy] phthalocyaninato zinc(II) (2) and 2,3,9,-10,16,17,23,24-octakis[3,5-bis(trifluoromethyl)phenoxy]phthalocyaninato indium(III) (3) are synthesized and characterized. Aggregation of the phthalocyanines was studied in tetrahydrofuran in different concentrations. Photochemical and photophysical properties of 2 and 3 in THF were investigated. A comparison between the photophysicochemical parameters of 2 and 3 yielded that 3 is a better photosensitizer than 2. The fluorescence quantum yields (ΦF) and 1O2 formation ([Formula: see text] for compound 3 are 0.016 and 0.84, respectively. The values for compound 2 are 0.135 and 0.54, respectively. The values of indium and zinc phthalocyanines (2 and 3) could be classified as photosensitizers in the photocatalytic applications such as photodynamic therapy (PDT) of cancer.

Synthesis of carboxylated silicon phthalocyanine photosensitive microspheres with controllable etching

Using a new kind of alkenyl silicon phthalocyanine, styrene (St) and methacrylic acid as monomers and potassium persulfate as an initiator, carboxylated silicon phthalocyanine photosensitive microspheres were synthesized by in-situ emulsion copolymerization. The structure and morphology of the microspheres were characterized by Fourier transform infrared spectroscopy (FT-IR)and scanning electron microscopy. Fluorescence spectrometer was used to characterize the optical property of the microspheres. The experimental results show that silicon phthalocyanine molecules with flexible unsaturated side chains have good compatibility with styrene. With the presence of carboxyl groups, the as-prepared photosensitive microspheres show high monodispersity and stability. On the basis of this, 9,10-diphenylanthracene (DPA) as singlet oxygen indicator was used to evaluate the photosensitivity of the microspheres. In addition, we report a novel phenomenon that the microspheres can be controllable etched by light irradiation with the presence of DPA in a specific solvent.

Dual-purpose zinc and silicon complexes of 1,2,3-triazole group substituted phthalocyanine photosensitizers: synthesis and evaluation of photophysical, singlet oxygen generation, electrochemical and photovoltaic properties

The synthesis, photophysical, singlet oxygen generation, electrochemical and photovoltaic properties of peripheral and axial 1,2,3-triazole group substituted zinc and silicon phthalocyanine complexes with strong absorption in the visible region were described. All novel complexes have been characterized by spectroscopic and electrochemical techniques. All the new compounds are highly soluble in most common organic solvents. The electronic absorption and fluorescence spectral properties of complexes 4 and 5 are investigated. The effects of the triazole group, different metal centers and position of the substituent on the photophysical, electrochemical and photovoltaic properties of the new phthalocyanines were also investigated for the first time in this work. According to the fluorescence measurements, the axially substituted silicon complex (5) showed higher fluorescence quantum yield (Φ_F = 0.28) than the peripherally substituted zinc complex (4). In addition, quantum yields for singlet oxygen generation (Φ_Δ = 0.32 for silicon complex (4) and Φ_Δ = 0.76 for zinc complex (5) in DMSO) were obtained. Electrochemical studies show that complex 5 is present in non-aggregated form as a result of steric hindrance of the axial groups; the LUMO level of this complex is slightly more negative than the conduction band of TiO₂ and electron injection might be less effective. Therefore, the power conversion efficiency of 1.30% for a complex 4 based dye-sensitized solar cell (DSSC) is higher than complex 5 (0.90%). Consequently, these zinc and silicon complexes are promising candidates not only for photodynamic therapy but also solar power conversion.

Evaluation of dual-purpose zinc and silicon phthalocyanine complexes on photophysical, singlet oxygen generation, electrochemical and photovoltaic properties.

Novel carboxylic acid terminated silicon(IV) and zinc(II) phthalocyanine photosensitizers: Synthesis, photophysical and photochemical studies

In order to improve the efficacy of photochemical properties for photodynamic therapy (PDT) applications, carboxylic acid groups axially conjugated with silicon(IV) and at the peripheral position with zinc(II) phthalocyanine skeletons for new photosensitizers to investigate the influence of the COOH group positions on the photophysicochemical performance are described in this study. Silicon (IV) (3 and 5) and zinc (II) (7) phthalocyanines were characterized by UV-vis, FTIR, 1H-NMR, MALDI-TOF MS and elemental analysis spectral data. Furthermore, the photophysical (fluorescence quantum yields and fluorescence quenching studies), photochemical (photodegradation and singlet oxygen generation) and aggregation properties of the newly synthesized phthalocyanines were investigated in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) solutions. The results were compared with that of zinc and silicon phthalocyanines. Singlet oxygen quantum yields ranged from 0.23 to 0.63 via Type II mechanism under the experimental conditions studied. The fluorescence of the phthalocyanine complexes (3, 5 and 7) is effectively quenched by 1,4-benzoquinone (BQ) in DMSO, DMF and THF.

Five-nuclear phthalocyanine complex bearing terpyridine zinc complex: Synthesis, and photophysicochemical studies

The context of this study is based on the synthesis of tetrakis{4-(2-([2,2[Formula: see text]:6[Formula: see text],2[Formula: see text]-terpyridine]Zn(II)-4[Formula: see text]-yl(methyl)amino)ethoxy)}phthalocyaninato zinc (II) (3) bearing four terpyridine-Zn(II) complexes that are directly linked through oxygen bridges to the macrocyclic core in order to create new supramolecular assemblies. The target phthalocyanine (3) was obtained by cyclotetramerization reaction of terpyridine-Zn (II) complex substituted phthalonitrile (2). All novel compounds synthesized in this study were fully characterized by general spectroscopic techniques such as FT-IR, UV-vis, and [Formula: see text]H-NMR, [Formula: see text]C-NMR, elemental analysis and mass spectroscopy. Spectral, photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen production and photodegradation under light irradiation) properties of newly synthesized phthalonitrile (2) and its phthalocyanine derivative (3) as five nuclear phthalocyanine were investigated in DMSO solutions.

Synthesis, characterization of new phthalocyanines and investigation of photophysical, photochemical properties and theoretical studies

This work describes the synthesis, spectral, aggregation and fluorescence properties of bis 4-[(4-tert-butylbenzyl)oxy substituted metal free (2), magnesium (3), zinc (4) and nickel (5) phthalocyanines. The syntheses of the novel compounds were confirmed by FT-IR, UV-vis, mass and NMR spectroscopy techniques, as well as elemental analysis. The effects of the nature of the central metal on the photophysical parameters of the phthalocyanine complexes are reported in this study. The photochemical properties (singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence behavior and fluorescence quantum yield) of the complexes were reported in different solutions (dimethyl sulfoxide (DMSO) and dimethyl formamide (DMF) and tetrahydrofuran (THF)). However, energy minimized structure, vibrational frequency, molecular orbital levels and electronic absorption spectra were obtained by DFT calculations which supported the experimental results.

Silicon(IV) phthalocyanine-biotin conjugates: Synthesis, photophysicochemical properties and in vitro biological activity for photodynamic therapy

Silicon (IV) phthalocyanines bearing one or two biotin groups on the axially positions were synthesized, and these novel phthalocyanines were characterized by elemental analysis and standard spectroscopic techniques such as FT-IR, [Formula: see text]H NMR, UV-vis and MALDI-TOF. The synthesized compounds are the first examples of axially biotin substituted silicon (IV) phthalocyanines. These phthalocyanines were designed as targeting photosensitizers for the treatment of cancer by photodynamic therapy (PDT) technique. The phthalocyanine ring was selected for its photosensitizer ability and the biotin group was selected as a targeting agent for increasing accumulation of these photosensitizers in tumor cells. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation) properties of the target silicon(IV) phthalocyanines were investigated in DMSO. The photosensitizing efficiency of the studied phthalocyanines was tested against human cervical cancer (HeLa) cells at different photosensitizer concentrations. Both axially mono- and bis-biotin substituted silicon(IV) phthalocyanines present high photocytotoxicity against HeLa cancer cells with the cell survival degree ranging from 13% to 50%. The photosensitivity and the intensity of damage were found to be directly related to the concentration of the used photosensitizers. According to the obtained results, both silicon(IV) phthalocyanine derivatives could be promising as photosensitizers for treatment of cancer by PDT technique.

Axially substituted silicon(IV) phthalocyanine and its quaternized derivative as photosensitizers towards tumor cells and bacterial pathogens

Axially di-(alpha,alpha-diphenyl-4-pyridylmethoxy) silicon(IV) phthalocyanine (3) and its quaternized derivative (3Q) were synthesized and tested as photosensitizers against tumor and bacterial cells. These new phthalocyanines were characterized by elemental analysis, and different spectroscopic methods such as FT-IR, UV-Vis, MALDI-TOF and ¹H NMR. The photophysical properties such as absorption and fluorescence, and the photochemical properties such as singlet oxygen generation of both phthalocyanines were investigated in solutions. The obtained values were compared to the values obtained with unsubstituted silicon(IV) phthalocyanine dichloride (SiPcCl₂). The addition of two di-(alpha,alpha-diphenyl-4-pyridylmethanol) groups as axial ligands showed an improvement of the photophysical and photochemical properties and an increasement of the singlet oxygen quantum yield (Φ_Δ) from 0.15 to 0.33 was determined. The photodynamic efficacy of synthesized photosensitizers (3 and 3Q) were evaluated with promising photocytotoxicity (17% cell survival for 3 and 28% for 3Q) against the cervical cancer cell line (HeLa). The photodynamic inactivation of pathogenic bacterial strains Streptococcus mutans, Staphylococcus aureus, and Pseudomonas aeruginosa suggested a high susceptibility with quaternized derivative (3Q). The both Gram-positive bacterial strains were fully photoinactivated with 11μM 3Q and mild light dose 50J.cm^-2. In case of P. aeruginosa the effect was negligible for concentrations up to 22μM 3Q and light dose 100J.cm^-2. The results suggested that the novel axially substituted silicon(IV) phthalocyanines have promising characteristic as photosensitizer towards tumor cells. The quaternized derivative 3Q has high potential for photoinactivation of pathogenic bacterial species.

Photophysical and photochemical properties of novel peripherally triethyleneoxysulfanyl substituted monomeric and Si–Si bonded dimeric silicon phthalocyanines

Monomeric and Si–Si bonded dimeric silicon(IV) phthalocyanines bearing 4[Formula: see text],7[Formula: see text],10[Formula: see text]-trioxaundecylsulfanyl groups were synthesized. These novel phthalocyanine derivatives were characterized by general analysis methods such as FT-IR, MALDI-TOF or HRMS, 1H NMR and UV-vis electronic absorption. Their aggregation behaviors were described in dimethyl sulfoxide (DMSO). In addition, the photophysical and photochemical properties of these phthalocyanines were also investigated in DMSO to determine potential of these phthalocyanines to acts as photosensitizer for photodynamic therapy (PDT) of cancer. Their high singlet oxygen generation demonstrated their suitability for PDT applications. These peripherally 4[Formula: see text],7[Formula: see text],10[Formula: see text]-trioxaundecylsulfanyl substituted silicon(IV) phthalocyanines are promising Type II photosensitizers owing to their favorable singlet oxygen generation capability. In addition, their fluorescence quenching behavior by 1,4-benzoquinone were also studied in DMSO.

Synthesis, Photophysical and Photochemical Properties of a Set of Silicon Phthalocyanines Bearing Anti-Inflammatory Groups

In this study, a series of novel silicon (IV) phthalocyanines conjugated axially with anti-inflammatory (sulindac) and triethylene glycol groups has been synthesized. Different synthetic strategies were attempted to obtain the targeted molecules in high yield. The compounds were fully characterized by using different analyses techniques. Our objectives were to generate a system with sulindac group which enhances the singlet oxygen generation and exhibits anti-cancer effect. Therefore, photophysical and photochemical properties of these compounds were investigated in different solvents. The substituent effect on fluorescence quantum yield and singlet oxygen generation was evaluated for efficiency in photodynamic therapy (PDT) as photosensitizer. The molecules exhibited no aggregation tendency, solubility in common organic solvents, high singlet oxygen quantum yield and high photostability in DMSO so these favourable properties make them good candidates as photosensitizer for PDT. In addition, their stabilities were investigated in DMSO, THF, acetonitrile and DMF.