Alexey Lyubimtsev

Aggregation behavior and UV-vis spectra of tetra- and octaglycosylated zinc phthalocyanines

Several tetra- and octaglycosylated PcZns 1a, 2a–2d, 3a-b and 4 were investigated for their aggregation behavior using different concentrations of the PcZn-species in pure DMSO, water and in various DMSO/water mixtures by comparing their UV-vis spectra. The PcZns 1–4 are independent of the concentration in pure DMSO and in up to 25 vol.% water/DMSO mixtures are non aggregated. Increasing amounts of water leads to higher aggregation ratios. The aggregation behavior is influenced by the nature and the position of the sugar substituents on the Pc-ring. PcZn4 was found the least aggregated compound even in pure water.

Synthesis and characterization of 1,8(11),15(18),22(25)-tetraglycosylated zinc(II) phthalocyanines

In continuation of our work on glycosylated phthalocyanines, a new series of 1,8(11),15(18),22(25)-tetraglycosylated zinc(II) phthalocyanines (PcZns) have been synthesized and characterized. 3-glycosylated phthalonitriles were synthesized through nitrite displacement in 3-nitrophthalonitrile with anomerically deprotected glycoses. The anomerically glycosylated phthalonitriles were then treated with hexamethyldisilazane (HMDS), trimethylsilyltriflate (TMSOTf) and zinc salt in DMF to form the corresponding acetyl-protected PcZns, followed by deprotection of acetyl groups by NaOMe in methanol/DMSO mixture. The formed unprotected tetraglycosylated PcZns are highly soluble in water, which is a necessary condition for potential biological applications.

Photophysics and photochemistry of octaglucosylated zinc phthalocyanine derivatives

The ground state electronic absorption spectra, photophysics and photochemistry of amphiphilic octaglucosylated zinc phthalocyanines containing oxygen or sulfur bridges are presented. Triplet quantum yield values for the two dyes (in DMF and DMSO) vary between 0.71 and 0.84, while singlet quantum yield values lie between 0.63 and 0.75. Fluorescence lifetimes were determined experimentally by time correlated single photon counting and semi-empirically by fluorescence quenching techniques; and values from both methods were within the same range. Kinetic data were obtained for the quenching of the triplet state of the phthalocyanines by ground state molecular oxygen; the bimolecular collisional quenching rate constant range between 2.35 × 108 and 1.13 × 109 M-1.s-1. These values suggest that triplet states of the dyes are effectively quenched by ground molecular oxygen.

Synthesis of glycosylated metal phthalocyanines and naphthalocyanines

The first part of this review summarizes methods for the syntheses of mono-, di-, and tetra-substituted glycosylated phthalonitriles, which are the main starting materials for the preparation of the corresponding glycosylated metal phthalocyanines. In the second part the preparation of symmetrically and unsymmetrically tetra- and octa- glycosylated zinc phthalocyanines in which the sugar is attached either anomerically or via another one of its OH-groups to the phthalocyanine macrocycle as well as other structurally different glycosylated metal phthalocyanines are reviewed.

Synthesis of unusual phthalocyanines and naphthalocyanines

This paper is a summary of the lecture Michael Hanack gave at the 5th ICPP meeting in Moscow. A new method for the preparation of phthalonitriles is reported which makes the syntheses of substituted phthalocyanines much easier. Then the generation of highly reactive dehydrophthalocyanines using different methods is described. The reaction of these intermediates with dienophiles and various solvents is also discussed. In the last section, the syntheses of tetra- and octa- Zn phthalocyanine and -naphthalocyanine carbohydrate conjugates, which will be used for photosensitizers in PDT, is reported.

Phthalocyanine conjugates with carbohydrates: synthesis and aggregation in aqueous solutions

The review is focused on the current state of the synthesis of glycosylated phthalocyanines and their precursors, mono-, di-, and tetraglycosyl phthalonitriles. Features of the synthesis of phthalogen conjugates with carbohydrates and the formation of related metal phthalocyanine complexes are discussed. The formation of aggregates of phthalocyanines in various media exerts a significant effect on the physicochemical and photochemical properties of phthalocyanine macrocycles, which is especially important in the practical use of phthalocyanines as photosensitizes. An aggregation of phthalocyanine conjugates in aqueous solutions strongly decreases the quantum yield of singlet oxygen, thus diminishing the biological activity of these compounds. Specific features of phthalocyanine conjugate aggregation with carbohydrates in aqueous solutions, organic solvents, and some their mixtures are analyzed.

Synthesis of meso-mono-phenylporphyrins with active groups in the benzene rings

The mono-meso-allyloxy- and acrylamidophenylporphyrins were synthesized from the corresponding hydroxy- and aminophenylporphyrins. All the compounds were characterized by IR, UV-Vis, 1H NMR and mass spectra.

Synthesis of Covalently-Linked Phthalocyanine–Phthalocyanine and Porphyrin–Phthalocyanine Dimers

The synthesis of the dimeric homonuclear phthalocyanines (Pc) 4a, 4b, 5a and 5b and the dimeric heteronuclear Pc 4c and 5c is reported. The reactions are carried out by coupling the monomeric Pc 1a and 1b each containing a phenolic OH group in one of its substituents with the bromoalkyl-substituted Pc 2a,b or 3a,b respectively. From the spectral data of 4a–c and 5a–c, it can be concluded that in dichloromethane and toluene as solvents, these binuclear Pc are equilibrating between cofacial and open conformations with the open form predominating. Changing the solvent polarity, e.g. by adding methanol, the equilibrium is shifted towards a cofacial conformation. Treatment of the Pc 2a,b and 3a,b with 5-(4′-oxyphenyl)-10,15,20-triphenylporphin (6) in a basic solution gives the porphyrins (P)-Pc dimers 7a,b and 8a,b respectively. In dichloromethane, the open conformation is preferred for the P-Pc dimers.

Synthesis of porphyrin monomers on the basis of meso-mono-hydroxy- and aminophenylporphyrins

The methods for the synthesis of porphyrins containing active vinyl groups on a periphery of the tetrapyrrole macroheterocycle are described. The possibility of their usage as comonomers in a copolymerization reaction with methyl methacrylate is given.

Reactivity of phthalocyanine precursors

A higher reactivity of 4-nitrophthalonitrile as compared to phthalonitrile and 4-amino-phthalonitrile in the reaction with sodium methoxide in methanol was demonstrated by theoretical (semiempirical, ab initio calculations) and experimental methods. The regioisomeric composition of substituted methoxyiminoisoindolenines was studied by analysis of products of their reaction with p-toluidine. The higher reactivity of 3-imino-1-methoxyisoindolenine as compared to 1,3-diiminoisoindoline in the reactions with nucleophilic agents (ammonia, p-toluidine) was shown by semiempirical calculations and kinetic methods.