Carbene-based ruthenium photosensitizers

Abstract

A new series of N-heterocyclic carbene (NHC)-pyridine ruthenium complexes incorporating a carbene unit as an ancillary ligand were designed and successfully synthesized by using simple synthetic methods. The photophysical, electrochemical and photovoltaic properties of these NHC-pyridine based ruthenium complexes were investigated. These complexes showed photoelectric conversion efficiencies in the range of 6.43 ∼ 7.24% under the illumination of AM 1.5 (100 mW cm(-2)). Interestingly, the modifications on the ancillary ligand of these sensitizers by removal of an alkoxyl group and replacement of the octyl chain with a 3,5-difluorobenzyl group showed a 13% increase in the conversion efficiency for the CifPR dye. These results demonstrated that structural modifications on the NHC-pyridine ancillary ligand of ruthenium complexes results in dye-sensitized solar cells exhibiting a comparable cell performance to that obtained using the standard N719 dye.

Ruthenium Sensitizers and Their Applications in Dye-Sensitized Solar Cells

“…It could be encouraging to replace the bipyridine ligand of the bipyridyl or polypyridyl complexes with neutral NHC ligands. Novel NHC-pyridine ruthenium sensitizers ( Figure 26) were successfully designed and synthesized [45,46]. These sensitizers result in efficient DSSCs with good sensitizing capability.…”

“…The effects of replacing a single polypyridyl ligand with an analogous anionic cyclometalating ligand were investigated [54]. Electrochemical and spectroscopic methods were Figure 26: Molecular structure of the new sensitizers CBTR, CfBTR, CiPoR, CifPoR, CifPR, and ester (taken from [45,46]). [49]) and A597 (taken from [50]).…”

Ruthenium (II) and iridium (III) complexes of N-heterocyclic carbene and pyridinol derived bidentate chelates: Synthesis, characterization, and reactivity

“…Counter anion exchange was achieved readily by stirring the halide salt ( 1 ) in NH 4 PF 6 or KPF 6 solution to form 2 (Scheme 3), by modifying literature procedures. [62]…”

“…Also, some bidentate and tridentate ligands have combined NHC and pyridine rings on one scaffold. [62–76] However, prior to our recent work, no ligands have combined NHC and pyridinol rings in a chelate. [27] As a result, we envisioned that by combining an NHC ring with a pyridinol ring, we would introduce a new ligand class that would combine the strong donor properties of the NHC moiety with the proton responsive pyridinol moiety.…”

Photodynamic Therapy in Skin Cancer

“…They have high affinity toward the lysosomes, but not the mitochondria, and they inhibit the growth of the tumor without toxicity for the normal cells (Jiang et al, 2010). N-heterocyclic (NHC) -pyridine complexes incorporating a carbene unit as an ancillary ligand were synthesized (Chen et al, 2011), chlorine compounds with conjugated substituents such as vynil groups and carboxylic acids (Eriksson & Eriksson, 2011), cyanine HM 118. Also, chlorine e6 (Ce6) -conjugated glycocol chitosan nanoparticles seem to have potential for PDT (Lee et al, 2011) as well as tumor-targeting albumin nanoparticles containing Ce6 .…”