Synthesis of a ruthenium(II) bipyridyl complex coordinated by a functionalized Schiff base ligand: Characterization, spectroscopic and isothermal titration calorimetry measurements of M2+ binding and sensing (M2+ = Ca2+, Mg2+)

Bis-[methylsalicylidine-4'benzoic acid]-ethylene (LH2) complexed with cis-Ru(bpy)(2)Cl-2 center dot 2H(2)O provides a complex of composition [Ru(bpy)(2)L)center dot 2NH(4)PF(6) (1), which has been characterized spectroscopically. Its binding behaviour towards Mg2+ and Ca2+ ions is monitored using H-1 NMR titration, isothermal titration calorimetry (ITC) and luminescence microscopy. The luminescent ruthenium complex binds Ca2+ in a more selective manner as compared to Mg2+. (C) 2009 Elsevier B.V. All rights reserved.