Synthesis, X-ray Structure, and Electrochemical and Excited-State Properties of Multicomponent Complexes Made of a [Ru(Tpy)<sub>2</sub>]<sup>2+</sup> Unit Covalently Linked to a -Catenate Moiety. Controlling the Energy-Transfer Direction by Changing the Catenate Metal Ion
1999-05-27T00:00:00Z (GMT) by
New multicomponent species consisting of -catenates incorporating the [Ru(tpy)<sub>2</sub>]<sup>2+</sup> moiety (tpy = 2,2‘:6‘,2‘ ‘-terpyridine) within their framework have been prepared, and their electrochemical and photophysical properties have been studied. The parent compound of the investigated species is a previously described Cu(I) catenate (<b>RuCu</b>) containing a [Cu(dap)<sub>2</sub>]<sup>+</sup> fragment (dap = 2,9-dianisyl-1,10-phenanthroline) used as a template and a [Ru(tpy)<sub>2</sub>]<sup>2+</sup> unit integrating one of the interlocked rings. Selective demetalation of the Cu(I) catenate moiety of <b>RuCu</b> afforded a catenand (<b>Ru</b>) containing the [Ru(tpy)<sub>2</sub>]<sup>2+</sup>-type component and a free tetrahedral coordination site. Reaction of this catenand with Ag<sup>+</sup> and Zn<sup>2+</sup> ions yielded two new bimetallic catenates (<b>RuAg</b> and <b>RuZn</b>, respectively). The solid-state structure of complexes <b>RuCu</b> and <b>RuAg</b> has been determined by X-ray diffraction. Electrochemical experiments have shown that the two moieties of the <b>RuCu</b> and <b>RuAg</b> catenates undergo independent redox processes. The photophysical properties of <b>Ru</b>,<b> RuCu</b>,<b> RuZn</b>, and<b> RuAg </b>have been investigated by steady-state and time-resolved techniques, and compared with those of appropriate model compounds. The absorption spectra do not show any appreciable ground-state electronic interactions between the -catM (cat = catenand, catM = catenate) and [Ru(tpy)<sub>2</sub>]<sup>2+</sup>-type moieties, whereas luminescence properties reveal the occurrence of efficient photoinduced intercomponent energy- and/or electron-transfer processes, whose direction depends on the presence or on the nature of the metal ion in the -cat-type moiety. In <b>Ru, </b><b>RuZn</b>, and<b> RuAg</b> such a moiety is quenched by the [Ru(tpy)<sub>2</sub>]<sup>2+</sup> unit, whereas for <b>RuCu</b> the opposite behavior is observed. The rate constant of intercomponent processes are determined via time-resolved nano- and picosecond luminescence spectroscopy.