Synthesis and properties in solution of rodlike, 2,2 prime :6 prime ,2 double prime -terpyridine-based ruthenium(II) coordination polymers

摘要

Rodlike ruthenium(II) coordination polymers have been prepared via the conversion of 4,4 double prime -bis(2,2 prime :6 prime ,2 double prime -terpyridine)-2 prime ,5 prime -dihexyl- p-terphenyl and an appropriately reactive ruthenium(III) species in 1-butanol/DMA. The diamagnetic polymers readily dissolve in polar organic solvents, and their homogeneous constitution could thus be proven and their degrees of polycondensation could be estimated to be Pn greater than or equal 30, using 1H and 13C NMR spectroscopy. The Pd-catalyzed polycondensation of bis[4 prime -(p-bromophenyl)-2,2 prime :6 prime ,2 double prime - terpyridine]ruthenium(II) tetrafluoroborate and 2,5-dihexylbenzene- 1,4-diboronic acid, on the other hand, which should lead to a constitutionally identical polymer, only resulted in oligomers under all tested conditions. The intrinsic viscosity [θ] of the high-molecular-weight polymers (determined in 0.02 M NH4PF6/DMA) is of the order of 300 mL g-1. In salt-free DMA solution and thus at low ionic strengths, the polymers display the characteristic polyelectrolyte behavior in viscosity experiments which becomes more and more pronounced with increasing Pn. The UV-vis absorption spectra recorded in DMA solution do not show any evidence of intramolecular electronic interactions of the metal centers along the polymer chains: on the contrary, the coordination polymers behave like sequences of electronically independent ruthenium(II) complexes.