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

Abstract

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,β_max) between the dipole moment μ and the main direction of the charge-transfer transition β_max.