853914-93-9Relevant academic research and scientific papers
Complexes of functionalized dipyrido[3,2-a:2′,3′-c]-phenazine: A synthetic, spectroscopic, structural, and density functional theory study
Lundin, Natasha J.,Walsh, Penny J.,Howell, Sarah L.,McGarvey, John J.,Blackman, Allan G.,Gordo, Keith C.
, p. 3551 - 3560 (2005)
The ligands 11-bromodipyrido[3,2-a:2′,3′-c]phenazine and ethyl dipyrido[3,2-a:2′,3′-c]phenazine-11-carboxylate have been prepared and coordinated to ruthenium(ll), rhenium(l), and copper(l) metal centers. The electronic effects of substitution of dipyrido[2,3-a:3′,2′-c] phenazine (dppz) have been investigated by spectroscopy and electrochemistry, and some photophysical properties have been studied. The crystal structures of [Re(L)(CO)3Cl] (L = ethyl dipyrido-[3,2-a:2′,3′-c] phenazine-11-carboxylate or 11-bromodipyrido[3,2-a:2′,3′-c] phenazine) are presented. Density functional theory calculations on the complexes show only small deviations in bond lengths and angles (most bonds within 0.02 A, most angles within 2°) from the crystallographic data. Furthermore, the vibrational spectra of the strongest Raman and IR bands are predicted to within an average 6 cm-1 for the complexes [Re(L)(CO)3Cl] and [Cu(L)-(triphenylphosphine)2]BF 4 (in the 1000-1700 cm-1 region). Spectroscopic and electrochemical evidence suggest that reduction of the complex causes structural changes across the entire dppz ligand. This is unusual as dppz-based ligands typically have electrochemical properties that suggest charge localization with reduction on the phenazine portion of the ligand. The excited-state lifetimes of the complexes have been measured, and they range from ca. 200 ns for the [Ru(L)(2,2×-bipyridine)2](PF6)2 complexes to over 2 μs for [Cu(11-bromodipyrido[3,2-a:2′,3′-c]phenazine) (PPh9)2](BF4) at room temperature. The emission spectra suggest that the unusually long-lived excited states of the copper complexes result from metal-to-ligand charge transfer (MLCT) transitions as they are completely quenched in methanol. Electroluminescent films may be fabricated from these compounds; they show MLCT state emission even at low doping levels [0.1% by weight in poly(vinylcarbazole) polymer matrix].
