Synthesis and magnetic properties of an annulated dinuclear copper(II) phthalocyanine peripherally having 2,6-dimethylphenoxy substituents

A dinuclear copper(II) phthalocyanine complex with 12 2,6-dimethylphenoxyl groups at the peripheral positions of the [CuPc]₂ framework, where [CuPc] units are linked by a common annulated benzene ring to give the planar dinuclear structure, was prepared and characterized. The introduced bulky 2,6-dimethylphenoxyl groups were revealed to effectively suppress the aggregation of the dinuclear complex in the toluene solution, showing a considerably red-shifted Q-band at 838 nm. The EPR spectrum (measured in the frozen toluene solution at 15 K) and temperature-dependent magnetic moment indicated the existence of antiferromagnetic interaction between the copper(II) ions. The exchange integral J was estimated to be -1.8 cm^-1 using Bleaney Bowers equation for the S₁ = S₂ = 1/2 system. The long-range interaction (Cu-Cu distance = 10.7 Å) through the common annulated benzene ring between two [CuPc] units was confrmed by the DFT calculation result.