Département de chimie moléculaire

Reaction of dimeric [RhII2(phen)2($μ$-OAc)2(MeCN)2](BF4)2 (phen = 1,10-phenanthroline) with pyrazine (pz) in a 1:2 ratio leads to the new 1-dimensional metal-metal-bonded coordination oligomer {\{}[RhII2(phen)2($μ$-OAc)2(pz)](BF4)2{\}}n (Rh-Rhpz)n (1), where each Rh atom of the dimeric unit (Rh-Rh) is coordinated in the equatorial plane to a nitrogen atom of a rigid and linear bifunctionalized org. linker (pz). Single x-ray diffraction anal. reveals the 1-dimensional straight oligomeric chain structure (mol. wire, MW) consists of alternating (Rh-Rh) units and pz linking ligands with free BF4- as counteranions, and each metal center has a slightly distorted octahedral arrangement. The presence of accessible labile MeCN groups on both ends of these MWs (free ends) enables functionalization of a 4-mercaptopyridine-gold coordinating platform (Au/MP) to form in one step a layer of coordination oligomer (Au/MP(Rh-Rhpz)n; n ≈ 50). Also (Rh-Rhpz)n (n = 1-6) MWs were grafted to Au/MP surfaces by a conventional step-by-step assembly construction involving coordination reactions between the Rh dimer ([Rh2(phen)2($μ$-OAc)2(MeCN)2](BF4)2 (2)) and pz. A detailed physicochem. study (UV-visible, RAIR, QCM-D, ellipsometry, contact angle measurements, as well as impedance spectroscopy and cyclic voltammetry) was made during both assembly methods to characterize the resulting surface-anchored coordination mol. wire (CMW) layers (Au/MP(Rh-Rhpz)n). The immobilized mol. assemblies (MAs) were successfully fabricated using both methods of assembly. The efficiency of the two methods is discussed. [on SciFinder(R)]