Alexander V. Dzuban

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.

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.