Modulation of photoinduced energy-transfer between Ru(II) and Os(II) termini in a dinuclear complex by a conformational change induced by Ba2+ binding at a central macrocyclic site

In a dinuclear complex containing fRuðbpyÞ3g2þ and fOsðbpyÞ3g2þ termini separated by a flexible diaza-18-crown-6 macrocyclic spacer, binding of a Ba2þ ion at the central macrocycle results in an increase in the Ru Os separation for electrostatic reasons, and hence a decrease in the efficiency of Ru ! Os photoinduced energy-transfer.