N,N′-Bis(aryl)pyridine-2,6-dicarboxamide complexes of ruthenium: Synthesis, structure and redox properties

Novel ruthenium sensitizers with a dianionic tridentate ligand for dye-sensitized solar cells: the relationship between the solar cell performances and the electron-withdrawing ability of substituents on the ligand

“…Such a binding mode of the pyridine-2,6-dicarboxyamide derivative to the ruthenium(II) atom was confirmed previously by X-ray crystallographic analysis for structural analogues. 12 In the case of TUS-29, information on the binding mode of pyridine-2,6-dicarboxyamide could not be obtained from the 1 H NMR spectrum due to its relatively lower solubility (the 1 H NMR spectrum was obtained using a basic mixed solution of CD 3 OD and NaOD). However, pyridine-2,6-dicarboxyamide seems to serve as a dianionic tridentate ligand as its other derivatives because TUS-29 showed similar photo-and electrochemical properties to the other TUS sensitizers (vide infra).…”

“…On the other hand, it is reported that Ru(terpy) (L) (L = N,N′-bis(4-methoxyphenyl)pyridine-2,6-dicarboxyamidato) displays two quasi-reversible oxidations at 0.16 and 0.94 V vs. SCE, and these two oxidations are assigned to the Ru(II)/ Ru(III) couple and the amidato-ligand-centered oxidation, respectively. 12 From the structural similarity between Ru(terpy)(L) and TUS sensitizers, the second quasi-reversible oxidation observed for TUS-31 seems to be the amidato-ligand-centered oxidation. It is also reported that these two oxidation potentials shift in the negative direction with increasing the electron-donating ability of the substituents on the phenyl units.…”

“…It is also reported that these two oxidation potentials shift in the negative direction with increasing the electron-donating ability of the substituents on the phenyl units. 12 Since TUS-31 has quite strong electron-donating substituents (-NMe 2 ) on the phenyl units, the oxidation potential of the amidato-ligand-centered oxidation seems to shift largely in the negative direction compared with the other TUS sensitizers. Therefore, only TUS-31 displayed the second oxidation in the potential range below 1.0 V vs. SCE.…”

“…Actually, the energy level of HOMO of Ru(terpy)(L) (L = N,N′-bis-(4-phenyl)pyridine-2,6-dicarboxyamidato), which is a structural analog of TUS sensitizers, was reported to be 0.2 V vs. SCE. 12 This value is much higher for the effective reduction by I − ; therefore, a substituent with a relatively strong electron-withdrawing ability is considered to be crucial to adjust the donor ability of the pyridine-2,6-dicarboxyamidato derivative ligand, and the energy levels of HOMOs of TUS sensitizers. Here we report the syntheses, and photo-and electrochemical properties of five novel TUS sensitizers with different substituents on the dianionic tridentate ligand.…”

Synthesis of Metallo-Supramolecular Polymers with Bis-NNN-Tridentate Ligand for Electrochromic Devices

“…Here we report a novel bis-NNN-tridentate pyridinecarboxamide ligand (L1) and the corresponding metallo-supramolecular polymers ( Figure 1). The metal complexes of pyridinecarboxamide have been reported and showed multi redox state and electrochromic property [23][24][25]. Introducing this type structure to the metallo-supramolecular polymer, novel good electro-active materials are expected.…”