Synthesis, Characterization, Solid-State Structures, and Spectroscopic Properties of Two Catechol-Based Luminescent Chemosensors for Biologically Relevant Oxometalates
作者:Helen D. Batey、Adrian C. Whitwood、Anne-K. Duhme-Klair
DOI:10.1021/ic700554n
日期:2007.8.1
The new heteroditopic ligand 2,3-dihydroxy-N-(1,10-phenanthroline-5-yl)benzamide (H-2-L-3) was synthesized and coordinated to [Ru(bpy)(2)(phen)](2+)- and [ReBr(CO)(3)(phen)]-type luminophores (bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline). The resulting chemosensors [Ru(bpy)(2)(H-2-L-3)](2+) and [ReBr(CO)(3)(H-2-L-3)] were fully characterized and their solid-state structures and spectroscopic properties were investigated to assess how the photophysical properties of the luminescent signaling units affect the performance of the sensors. [Ru(bpy)(2)(H-2-L-3)](2+) and [ReBr(CO)(3)(H-2-L-3)] both signal the presence and concentration of molybdate and vanadate in aqueous acetonitrile through a decrease in emission intensity. [ReBr(CO)(3)(H-2-L-3)] also detects tungstate. Due to the higher emission intensity of the Ru-based sensor, its detection limits for molybdate (43 mu g L-1) and vanadate (24 mu g L-1) are almost 1 order of magnitude lower than the ones achieved with the Re-based sensor. The optimum working pH of the chemosensors is determined by the pK(a) values of the 2-hydroxy-groups of the receptor units: pH 4 for [ReBr(CO)(3)(H-2-L-3)] and pH 3 for [Ru(bpy)(2)(H-2-L-3)](2+). Both sensors are selective: equimolar amounts of PO43-, SO42-, ReO4-, Mn(II), Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) do not interfere with the detection of molybdate or vanadate.