Experimental All starting materials were commercially available and used as purchased, unless stated otherwise. Solvents were purified by standard methods before use. Copper(II) complex 1 was synthesized as previously described 1 . Caution: Although no problems were encountered during the preparation of perchlorate salts, suitable care should be taken when handling such potentially hazardous compounds. Elemental analyses were performed by the Service Central d'Analyse du CNRS in Lyon, Solaize,

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... rance.Electrospray mass spectra were recorded on an Esquire 3000 plus Bruker Daltonics with nanospray inlet. UV-visible spectra were recorded using quartz cuvette (1.0 cm) and a Varian Cary 50 UV-Visible spectrophotometer equipped with a Peltier thermostating accessory. Synthesis of the copper(II) complex [Cu 2 (BPMP)(KA)] (ClO 4 ) 2 (1-KA). To a solution of complex 1 (19 mg, 0.02 mmol, 1 eq) in methanol (3 ml) and a small amount of acetone was added a solution of kojic acid (64 mg, 0.45 mmol, 22 eq.) in methanol (3 ml) and a small amount of water. The solution was stirred 30 min and filtered. The green filtrate is slow evaporated and after 3 weeks, pale green crystals of 1-KA suitable for X-Ray diffraction