Synthesis of Panchromatic Ru(II) Thienyl-Dipyrrin Complexes and Evaluation of Their Light-Harvesting Capacity

Abstract

Ru(II) complexes with 5-(3-thienyl)-4,6-dipyrrin (3-TDP), containing 2,2'-bipyridine (bpy) or 4,4'-bis(methoxycarbonyl)-2,2'-bipyridine (dcmb) as coligands, have been prepared and extensively characterized. Crystal structure determination of [Ru(bpy)(2)(3-TDP)]PF(6) (1a) and [Ru(bpy)(3-TDP)(2)] (2) reveals that the 3-thienyl substituent is rotated with respect to the plane of the dipyrrinato moiety. These complexes, as well as [Ru(dcmb)(2)(3-TDP)]PF(6) (1b), act as panchromatic light absorbers in the visible range, with two strong absorption bands observable in each case. A comparison to known Ru(II) complexes and quantum-chemical calculations at the density functional theory (DFT) level indicate that the lower-energy band is due to metal-to-ligand charge transfer (MLCT) excitation, although the frontier occupied metal-based molecular orbitals (MOs) contain significant contributions from the 3-TDP moiety. The higher energy band is assigned to the π-π* transition of the 3-TDP ligand. Each complex exhibits an easily accessible one-electron oxidation. According to DFT calculations and spectroelectrochemical experiments, the first oxidation takes place at the Ru(II) center in 1a, but is shifted to the 3-TDP ligand in 1b. An analysis of MO energy diagrams suggests that complex 1b has potential to be used for light harvesting in the dye-sensitized (Grätzel) solar cell.

Synthesis of Porphyrinoids, BODIPYs, and (Dipyrrinato)ruthenium(II) Complexes from Prefunctionalized Dipyrromethanes

“…[77] Again, in all cases, the desired amino-substituted bis(2,2′bipyridyl)(dipyrrinato)ruthenium(II) complexes (51)(52)(53)(54)(55) were obtained in good to excellent yields (Table 6). [77] Again, in all cases, the desired amino-substituted bis(2,2′bipyridyl)(dipyrrinato)ruthenium(II) complexes (51)(52)(53)(54)(55) were obtained in good to excellent yields (Table 6).…”

A Family of RuII Photosensitizers with High Singlet Oxygen Quantum Yield: Synthesis, Characterization, and Evaluation

“…Many of the existing ruthenium‐based 1 O 2 photosensitizers are more efficient than the well‐established organic photosensitizer methylene blue and of comparable efficiency to the widely used rose bengal 19–28. In 1977, Demas and co‐workers studied 16 luminescent complexes of Ru II , Os II , and Ir III of the general type [ML 3 ] 2+ (M is the metal ion, and L is a bipyridyl‐type ligand) 21.…”

Computational Molecular Nanoscience Study of the Properties of Copper Complexes for Dye-Sensitized Solar Cells

“…The strong absorptivity of these complexes is due to a metal-to-ligand charge transfer (MLCT) transition [26]. These complexes have reached over 12% power conversion efficiency [27]; but the rarity and high cost of the Ru may limit their practical usage.…”