Unprecedented single-crystal-to-single-crystal topochemical conformational change and photoreduction of ethylene units in π-stacked metallomacrocycle

Neutral π-stacked metallomacrocycle was prepared using fac-Re(CO)3, and linear ditopic π-conjugated nitrogen donors in water–toluene mixture under reflux condition. Two ethylene units in the cycle are parallel to each other with a distance of 3.4 Å, which undergo topochemical conformational change from a parallel conformation to criss-cross conformation and photoreduction under UV-light irradiation through single-crystal-to-single-crystal transformation (SCSC). The π-stacked cycle and its photoproducts were characterized by 1H NMR spectroscopy and X-ray diffraction studies.