Alexander Yu. Tolbin

Synthesis of 1,2-bis(3,4-dicyanophenoxymethyl)benzene and binuclear zinc phthalocyanines of clamshell and ball types

A novel 1,2-bis(3,4-dicyanophenoxymethyl)benzene was synthesized from 1,2-bis-(hydroxymethyl)benzene and 4-nitrophthalodinitrile. Its condensation with 4-tert-butylphthalodinitrile results in a binuclear phthalocyanine of clamshell type. Reaction of bisphthalodinitrile with a large excess of zinc acetate gives rise to a binuclear phthalocyanine of ball type (33% yield). The successful syntheses of these binuclear phthalocyanines were carried out by microwave irradiation and solid phase methods.

Peripheral functionalisation of a stable phthalocyanine J-type dimer to control the aggregation behaviour and NLO properties: UV-Vis, fluorescence, DFT, TDHF and thermal study

This novel research opens the possibility of controlling the spectral, fluorescent and non-linear optical (NLO) properties of stable J-type phthalocyanine dimers. In our group, thermally and chemically stable supramolecular J-type dimers, based on low-symmetry phthalocyanine macrocycles, have been synthesised for the first time, and the present work is a fruitful continuation of the initiated studies. Using an example of a dimeric magnesium complex, consisting of the same anti-parallel oriented 2-hydroxy-9,10,16,17,23,24-hexabutylphthalocyanine macrocycles, we first demonstrated the ability of stable phthalocyanine J-dimers to undergo peripheral functionalisation. UV-Vis, fluorescence and DFT studies showed that when 2-(diethylphosphoryl)-4-methylpenta-1,3-dienyl-3-oxy-moieties are introduced into a dimer structure, the intermolecular association of large molecules varies significantly, tending to ordering. Simulation of the nonlinear optical properties with the TDHF/6-311++G** theoretical approximation has shown that the chemical alteration of a dimeric structure results in an increasing polarisability (α), first hyperpolarisability (β) and an angle θ(μ,βmax) between the dipole moment μ and the main direction of the charge-transfer transition βmax.

A highly stable double-coordinated 2-hydroxy-tri(tert-butyl)-substituted zinc phthalocyanine dimer: synthesis, spectral study, thermal stability and electrochemical properties

A highly stable J-type dimer based on 2-hydroxy-tri(tert-butyl)-substituted zinc phthalocyanine with specific supramolecular architecture was investigated by UV-visible and fluorescence spectroscopy and by cyclic voltammetry to show strong π–π interactions and coordination between hydroxy-groups and Zn2+ central metal ions. The possibility of controlling the fluorescent properties of the obtained complex by using different solvents is demonstrated, which, along with the high thermal stability according to the thermoanalytical study, may increase practical applicability of supramolecular dimeric phthalocyanine compounds.

Directed synthesis of bi- and polynuclear clamshell-type phthalocyanines and their physico-chemical investigations

Novel bi-, tri- and tetranuclear butyl- and tert-butyl-substituted clamshell-type phthalocyanines were synthesized starting from 2-hydroxyphthalocyanines with quantitative yields. The structures of the obtained compounds were characterized by a complex of NMR spectroscopy and mass spectrometry techniques. Applying electronic absorption spectroscopy (UV-vis) and density functional theory (DFT) showed the complicated conformation equilibria for the spacer-bonded macrocyclic compounds and led us to estimate their behavior dependent on the number and relative orientation of macrocycles.

Slipped-cofacial J-type phthalocyanine dimers as potential non-linear absorbers for optical limiting applications

We found, for the first time, that in the presence of HClO4, a slipped-cofacial magnesium J-type phthalocyanine dimer is subjected to demetallation, providing a thermally stable metal-free derivative, as proven by NMR and UV/Vis spectroscopy, as well as by MALDI-TOF mass spectrometry. Our thermoanalytical study demonstrated the high thermal stability of the dimeric ligand (up to 614 °C). The presence of tert-butyl substituents in the dimeric structures allowed us to discover, with the help of field emission scanning electron microscopy (FE-SEM), ordered phases, represented as threads composed of about 200 nm diameter circles, unlike the corresponding monomers, in which similar circles or triangles are scattered randomly. The interaction of the metal-free dimer with magnesium acetate gave an initial dimeric complex with intrinsic spectral properties. Simulation of the optical limiting (OL) properties using the finite field TDDFT (FF-TDDFT) approach (PBE/aug-cc-pVDZ) revealed that the limiting effect for J-type dimers is more pronounced in the visible region, whereas in the near-IR region, at low input fields, they can be used as linear optical filters.

Self-assembly of 2-hydroxy-tri-tert-butylphthalocyaninato zinc into J-type dimer: UV-vis, DFT and spectropotentiometric study

The role of the base nature during complexation of 2-hydroxy-9(10),16(17),23(24)-tri-tert-butyl-29H,31H-phthalocyanine ligand (1) with zinc acetate was studied by the UV-vis spectroscopy and DFT calculations. The latter allowed us to explain the selective formation of double-coordinated J-type dimer in the presence of lithium methoxide. Spectropotentiometry was used to study the nucleophilic properties of the dimeric complex in comparison with the corresponding monomer and has demonstrated the strong intramolecular interactions of macrocycles.

DFT study of the potential energy surfaces towards the searching of the stable self-assembled phthalocyanine dimers

We have applied the density functional theory (DFT) to find stable dimeric structures on the potential energy surfaces (PESs) of slippage, tilting and rotation of the macrocycles of monohydroxy magnesium phthalocyanine complex. Gradual changing of a distance between Mg2+ ions and oxygen atoms of the OH-groups, as well as the dihedral angles between the planes passing through the isoindoline nitrogen atoms of different macrocycles has allowed finding of six stable dimeric structures that differ from each other by the spatial arrangement of the macrocycles. The most stable structure was found for the dimer in which two equivalent low-symmetry phthalocyanine macrocycles are double fixed by the coordination bonds between the complexing metal ions and oxygen of the OH-groups. This result is in agreement with our earlier experimental data.

Synthesis of phthalocyanine compounds bearing 2-(diethoxyphosphoryl)-4-methylpenta-1,3-dienyl functional groups

Free-base phthalocyanine ligands and their zinc derivatives representing functionally monosubstituted (A3B type) or tetrasubstituted (A4 type) compounds with 2-diethoxyphosphoryl-4-methylpenta-1,3-dienyl moieties have been synthesized for the first time. Their structures were characterized by MALDI-TOF mass-spectrometry as well as 1H and 31P NMR spectroscopy data. A tendency to aggregation in dependence on the nature of the solvent was demonstrated as well.

Development of direct methods to produce nanosize structures using phthalocyanine-based building blocks

Convenient and accessible synthetic methods for planar and clamshell-type binuclear phthalocyanines including Ln(III) complexes (Ln = Dy, Yb, Lu) were developed. Compounds obtained were shown to be promising building blocks for the preparation of nanosized polynuclear phthalocyanines.

Aggregation of slipped-cofacial phthalocyanine J-type dimers: Spectroscopic and AFM study

Direct metallation of 2-hydroxyphthalocyanine J-type slipped-cofacial dimeric ligand by Mg, Zn, Cu, Ni and Co salts has been carried out to obtain corresponding metal complexes selectively without any noticeable dissociation or polymerization of the starting ligand. Integrated analysis of aggregation properties in the synthesized series has been conducted with the involvement of AFM microscopy, UV/Vis spectroscopy and theoretical assessment. As a result, a nonlinear relationship between absorption and concentration was found, with aggregation beginning to appear at concentrations above 3.3 × 10-5 mol L-1 with predominant formation of trimers from the dimeric molecules in THF solutions.