Synthesis and properties of dithienylethene-based binuclear gold complexes and a palladium chlorine-bridged macrocycle

Two dithienylethene-based binuclear gold complexes and a palladium chlorine-bridged macrocycle bearing bis(phosphine) ligands have been synthesized. Their structures have been thoroughly characterized by NMR spectrometry, single-crystal X-ray diffraction, and elemental analyses. The two binuclear gold complexes display excellent photoisomerization properties upon irradiation with UV/Vis light in CH2Cl2. Moreover, we found that the introduction of metal atoms can stabilize the dithienylethene-based bis(phosphine) ligands, and that the absorption spectra of gold complexes 3 and 4 showed 6–12 nm red-shifts upon irradiation with UV light compared with those of the ligands 1 and 2. However, no such isomerization was observed when the palladium chlorine-bridged macrocycle 5 in CH2Cl2 was irradiated with UV light, but it showed excellent catalytic activity for the Suzuki coupling reaction. Moreover, we found that the non-photochromic macrocycle 5 can perform the photochromic reaction when the solution of CH3CN was irradiated by UV light.

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► Dithienylethene bis(phosphine) gold complexes can easily isomerize.
► A palladium chlorine-bridged macrocycle was obtained.
► The macrocycle can catalyze the Suzuki coupling reaction.
► The macrocycle can perform photochromic reaction in CH3CN, not in CH2Cl2.