We present four new tetraruthenium macrocycles built from two 1,4-divinylphenylene diruthenium and two isophthalic acid building blocks with peripheral, potentially mono- or tridentate donor functions attached to the isophthalic linkers.These macrocycles are characterized by multinuclear NMR spectroscopy, mass spectrometry and, in the case of the thioacetyl-appended complex 4, by X-ray crystallography.Cyclic and square wave voltammetry establish that the macrocycles can be oxidized in four consecutive redox steps that come Chinese Chef Knives as two pairs of two closely spaced one-electron waves.Spectroscopic changes observed during IR and UV/Vis/NIR spectroelectrochemical Collections experiments (NIR = near infrared) show that the isophthalate linkers insulate the electroactive divinylphenylene diruthenium moieties against each other.The macrocycles exhibit nevertheless pronounced polyelectrochromism with highly intense absorptions in the Vis (2+/4+ states) and the NIR (2+ states) with extinction coefficients of up to >100,000 M−1·cm−1.
The strong absorptivity enhancement with respect to the individual divinylphenylene diruthenium building blocks is attributed to conformational restrictions imposed by the macrocycle backbone.Moreover, the di- and tetracations of these macrocycles are paramagnetic as revealed by EPR spectroscopy.