Phthalocyanines prepared from 4,5-dihexylthiophthalonitrile, a popular building block

Phthalocyanines are tetrapyrrolic artificial porphyrinoids that play major roles in advanced biological and technological applications. Research on this family of dyes is particularly active in Türkiye, with many derivatives being prepared from 4,5-dihexylthiophthalonitrile DiSHexPN, which is one of the most popular noncommercially available building blocks for phthalocyanines. This review summarizes the phthalocyanines and their versatile properties and applications that have been published since 1994, when the synthesis of DiSHexPN was first described, to emphasize the importance of this building block in plentiful applications, all with biomedical or technological impact.

Dually directional glycosylated phthalocyanines as extracellular red-emitting fluorescent probes

The development of new non-aggregated phthalocyanines bearing multivalent saccharide moieties on their macrocyclic rims is of great interest. Many characteristics, including water-solubility, non-toxicity and others, can be feasibly obtained by these amphiphiles which can be considered as a key solution for demonstrating highly efficient photoactive materials in water. Herein, a family of five newly prepared dually directional Zn(ii) containing phthalocyanines (PcG1-4) and azaphthalocyanine (AzaPcG1) glycoconjugates is described. The unique spatial arrangement of the glucoside units based on peripherally hexadeca-(PcG1) and nonperipherally octa-(PcG4) macrocycles provides a fully monomeric behaviour along with a high fluorescence (Φ_F∼ 0.21) in aqueous solution. These amphiphiles were characterized by low toxicity, and an extremely low cellular uptake was obtained due to the highly polar nature of the glucoside substituents. Accordingly, their potential as suitable photoactive chromophores for red-emitting extracellular fluorescent probes has been confirmed upon the evaluation of paracellular transport using a layer of MDCKII cells with the permeability coefficient fully comparable with an established evaluator of the integrity of the monolayer.

Synthesis and spectroscopic characterization of novel methoxy bridged benzimidazolyl-substituted phthalocyanines as potent inhibitors of urease

In this study, novel peripherally 4-[(1H-benzimidazol-1-yl)methoxy] substituted Zn(II) (3) Cu(II) (4) and Co(II) (5) phthalocyanines were prepared and their structures were characterized spectroscopically. The light absorption behaviors of the synthesized compounds (3-5) were studied by UV-Vis spectroscopy at different concentrations in different solvents. The urease inhibition activities of the synthesized compounds were also investigated. Among the synthesized molecules, compound 4 showed the best inhibitory effect against jack bean urease with IC₅₀ values of 0.0036 ± 0.0010 μM.

The synthesis of star-shaped poly(N-isopropylacrylamide) with two zinc porphyrins as the core and end groups via ATRP and “CLICK” chemistry and a photocatalytic performance study

The synthesis of star-shaped poly(N-isopropylacrylamide) with two zinc porphyrins as the core and end groups via ATRP & “CLICK” chemistry and a photocatalytic performance study.

Fluorescent glycoconjugates and their applications

Fluorescent glycoconjugates are discussed for their applications in biology in vitro, in cell assays and in animal models. Advantages and limitations are presented for each design using a fluorescent core conjugated with glycosides, or vice versa.

Macromolecular hexa-asymmetric zinc(II) phthalocyanines bearing triazole-modified triphenylene core: Synthesis, spectroscopy and analysis towards volatile organic compounds on Surface Acoustic Wave devices

The synthesis and characterization of novel asymmetric zinc(II) phthalocyanines (4–9) and their linking through peripheral and nonperipheral positions on the phthalocyanine ring via click coupling to alkyne-functionalized 2,3,6,7,10,11-hexakis(prop-2-ynyloxy)triphenylene core are described for the first time. These phthalocyanines (Pcs) (4–12) were characterized by elemental analysis and different spectroscopic techniques such as UV-vis, 1H-NMR, FT-IR and mass spectroscopy. Furthermore, the utilization of thin films of novel Pcs as a sensitive layer for detection of lung cancer from exhaled human breath at room temperature under exposure to marker volatile organic compounds (VOCs) are presented. The developed sensors were tested for acetone, ethanol, [Formula: see text]-hexane, toluene, chloroform and isoprene in a range of 300–14560 ppm. The obtained results have confirmed the possibility of utilization of Pc-based Surface Acoustic Wave (SAW) sensors for medical diagnosis based on exhaled breath analysis.

Glycosylated zinc phthalocyanine-gold nanoparticle conjugates for photodynamic therapy: Effect of nanoparticle shape

In this work, we report on the synthesis of tris-[(2,2,7,7-tetramethyltetrahydro-3aH-bis([1,3]dioxolo)[4,5-b:4',5'-d]pyran-5-yl)methoxy)-2-(4-benzo[d]thiazol-2-ylphenoxyphthalocyaninato] zinc(II) (complex 3) and its linkage to gold nanoparticles (AuNPs) of different shapes through S-Au/N-Au self-assembly. The conjugates of complex 3 (with both gold nanorods (AuNR) and nanospheres (AuNS)), displayed decreased fluorescence quantum yield with corresponding improved triplet and singlet quantum yields compared to complex 3 alone, however 3-AuNR showed improved properties than 3-AuNS. Complex 3 showed relatively low in vitro dark cytotoxicity against the epithelial breast cancer cells with cell survival ≥ 85% at concentration ≤ 160 μg/mL but afforded reduced photodynamic therapy activity which may be due to aggregation. 3-AuNR afforded superior PDT activity with <50% viable cells at concentration ≥ 40 μg/mL in comparison to 3-AuNS with <50% viable cells at concentration ≥ 80 μg/mL. The superior activity of 3-AuNR is attributed to the photothermal therapy effect since nanorods absorb more light at 680 nm than nanospheres.

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.

Phthalocyanine-chalcone conjugates

A phthalocyanine-chalcone conjugate was previously reported to retain the full photodynamic activity of the phthalocyanine and a slightly lowered antivascular effect of the chalcone. Assuming that it was due to an insufficient release of the chalcone, we described here several grafting modes applied to the preparation of phthalocyanine-chalcone conjugates.

A combined experimental and computational study of the substituent effect on the photodynamic efficacy of amphiphilic Zn(ii)phthalocyanines

The interplay between structural features, photophysical characteristics and photodynamic efficacy of carbohydrate substituted amphiphilic Zn(ii)phthalocyanines is presented.

The synthesis and characterization of nonperipherally tetra terminal alkynyl substituted phthalocyanines and glycoconjugation via the click reaction

In order to obtain nonperipherally tetra terminal alkynyl substituted phthalocyanines (Pcs), new 3-pent-4-ynyloxy phthalonitrile (3) was prepared by the nucleophilic displacement reaction of 3-nitrophthalonitrile (1) and 4-pentyn-1-ol (2) and then cyclotetramerization was attained in the presence of zinc acetate, cobalt acetate, and/or DBU in n-pentanol without protection/deprotection. For the first time, the glycoconjugation of the nonperipherally tetra terminal alkynyl substituted zinc phthalocyanine (ZnPc) (6) can be easily achieved via the click reaction in a high yield. The electronic absorption spectrum of the glucopyranosyl substituted ZnPc (10) derivative showed a red-shifted Q band at 751 nm in dichloromethane due to the protonation of the meso nitrogens of the Pc macrocycle. Deacylation yielded ZnPc (11) bearing glucose substituents at nonperipheral positions with an improved water-solubility and non-aggregation in DMSO. The chemical structures of the new compounds were characterized by (1)H NMR, (13)C NMR, FT-IR, UV-Vis, mass spectrometry and elemental analysis. Moreover, the phthalonitrile compound was characterized using X-ray.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

Photophysicochemical properties and TD-DFT calculations of a novel terminal alkyne substituted metal free phthalocyanine

The synthesis of a novel free base tetrakis(prop-2-ynyloxy)phthalocyanine (2) is described, along with its characterization by IR, UV-visible absorption, and 1 H NMR spectroscopy and mass spectrometry. The compound exhibited good solubility in a wide range of organic solvents and no significant aggregation was observed over a wide concentration range. The values for the singlet oxygen (ΦΔ), photodegradation, fluorescence (ΦF) and triplet state quantum yields and the fluorescence and triplet state lifetimes are reported. A relatively high ΦΔ value of 0.46 was obtained in DMSO. The ability to carry out "click" chemistry at the ligand periphery enhances the potential utility of 2 for use in bioconjugates in photodynamic therapy (PDT). A moderately high ΦF value of 0.18 is observed for emission in the therapeutic window in the near-IR region, which suggests that it may also be possible to determine the level of localization of 2 in tumor cells through bioimaging.

Synthesis and photophysical properties of a novel ethynyl zinc(II) phthalocyanine and its functionalized derivative with click chemistry

The synthesis of novel, symmetrical zinc(II) phthalocyanine (ZnPc) bearing four ethynylcyclohexyloxy terminal moieties was achieved by cyclotetramerization of novel 4-(2-ethynylcyclohexyloxy) phthalonitrile in pentanol in the presence of DBU and zinc acetate without any protective/deprotective chemistry. Subsequently, this new zinc(II) phthalocyanine derivative was reacted with 6-azido-hexanoic acid under "click-chemistry" conditions to give phthalocyanine-hexanoic acid conjugates linked by 1,2,3-triazole units. The new compounds have been characterized by using elemental analyses, UV-vis, FTIR, 1 H NMR and mass spectroscopic data. The aggregation properties of the compounds were investigated in different concentrations. General trends are also described for fluorescence quantum yields and lifetimes of novel zinc derivatives in tetrahydrofuran. The fluorescence of the tetrasubstituted zinc(II) phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ) in THF.

Fully protected glycosylated zinc (II) phthalocyanine shows high uptake and photodynamic cytotoxicity in MCF-7 cancer cells

Phthalocyanine photosensitizers are effective in anticancer photodynamic therapy (PDT) but suffer from limited solubility, limited cellular uptake and limited selectivity for cancer cells. To improve these characteristics, we synthesized isopropylidene-protected and partially deprotected tetra β-glycosylated zinc (II) phthalocyanines and compared their uptake and accumulation kinetics, subcellular localization, in vitro photocytotoxicity and reactive oxygen species generation with those of disulfonated aluminum phthalocyanine. In MCF-7 cancer cells, one of the compounds, zinc phthalocyanine {4}, demonstrated 10-fold higher uptake, 5-fold greater PDT-induced cellular reactive oxygen species concentration and 2-fold greater phototoxicity than equimolar (9 μm) disulfonated aluminum phthalocyanine. Thus, isopropylidene-protected β-glycosylation of phthalocyanines provides a simple method of improving the efficacy of PDT.

Synthesis, properties and near-infrared imaging evaluation of glucose conjugated zinc phthalocyanine via Click reaction

In order to develop a novel near infrared fluorescence agent, glucose conjugated zinc phthalocyanine, [2,9(10),16(17),23(24)-tetrakis((1-(β-D-glucopyranose-2-yl)-1H-1,2,3-triazol-4-yl)methoxyl)phthalocyaninato]zinc(II), was synthesized via Click reaction. Their chemical structures were characterized by mass spectrometry, nuclear magnetic resonance spectrum. Their light stability and fluorescence quantum yield were evaluated by UV-visible and fluorescent spectroscopic method. Optical imaging in vivo was performed with this saccharide conjugated phthalocyanine as probe on liver tumor-bearing nude mice. Near-infrared imaging effect, organ aggregation as well as distribution of probe in vivo were evaluated by in vivo fluorescence imaging technique. Results show that glucose conjugated zinc phthalocyanine has favorable water solubility, good optical stability and high emission ability in near infrared region. Imaging results demonstrate that saccharide conjugated phthalocyanine has possess obvious imaging effect in vivo, which implies its potential in cancer diagnosis as near infrared optical probe.

Click chemistry: the emerging role of the azide-alkyne Huisgen dipolar addition in the preparation of substituted tetrapyrrolic derivatives

The review aims at being an exhaustive summary of the use of Huisgen azide-alkyne dipolar addition in the synthesis of tetrapyrrolic compounds, mainly porphyrins, phthalocyanines, chlorins and bacteriochlorins.

Photodynamically active phthalocyanine building blocks for click chemistry

Synthesis of symmetrical and unsymmetrical zinc phthalocyanines from two different precursors 4,5-bis(tert-butylsulfanyl)phthalonitrile (A) and N-(3-azidopropyl)-2,3-dicyanoquinoxaline-6-carboxamide (B) is described. Congeners of AAAA, AAAB, ABAB and AABB type were isolated by a chromatographic technique, however, the congener of BBBB type had to be prepared in a separate reaction. The adjacent and opposite isomers were also separated and fully characterized. Isolated phthalocyanines contained different number of azide groups, a substrate for highly efficient Cu(I) -catalyzed azide-alkyne 1,3-dipolar cycloaddition ("click chemistry"). All phthalocyanines absorbed strongly (ε over 150 000 M-1.cm-1) over 700 nm. Their singlet oxygen quantum yields were determined in DMF and ranged from 0.63 to 0.79, fluorescence quantum yields in DMF were considerably lower in the range 0.03–0.06. All these properties make them suitable building blocks for a simple modification and a synthesis of phthalocyanines with better tuned properties for photodynamic therapy.