84175-08-6Relevant articles and documents
Electronic effects on reactivity and anticancer activity by half-sandwich N,N-chelated iridium(iii) complexes
Guo, Lihua,Zhang, Hairong,Tian, Meng,Tian, Zhenzhen,Xu, Yanjian,Yang, Yuliang,Peng, Hongwei,Liu, Peng,Liu, Zhe
, p. 16183 - 16192 (2018/10/04)
The synthesis and characterization of a series of organometallic half-sandwich N,N-chelated iridium(iii) complexes bearing a range of electron-donating and withdrawing substituents were described. The X-ray crystal structures of complexes 1, 3 and 5 have been determined. This work demonstrated how the aqueous chemistry, catalytic activity in converting coenzyme NADH to NAD+ and anticancer activity can be controlled and fine-tuned by the modification of the ligand electronic perturbations. In general, the introduction of an electron-withdrawing group (-Cl and-NO2) on the bipyridine ring resulted in increased anticancer activity, whereas an electron-donating group (-NH2,-OH and-OCH3) decreased the anticancer activity. Complex 6 bearing a strongly electron-withdrawing NO2 group displayed the highest anticancer activity (7.3 ± 1.2 μM), ca. three times as active as cisplatin in the A549 cell line. Notably, selective cytotoxicity for cancer cells over normal cells was observed for complexes 1 and 6. DNA binding does not seem to be the primary mechanism for cancer fighting. However, the aqueous chemistry, cell apoptosis and cell cycle, which show similar dependence on the ligand electronic perturbations as the anticancer activity, appear to together contribute to the anticancer potency of theses complexes. This work may provide an alternative strategy to enhance anticancer activity for these N,N-chelated organometallic half-sandwich iridium(iii) complexes.
Ruthenium(II)–Pyridylimidazole Complexes as Photoreductants and PCET Reagents
Pannwitz, Andrea,Prescimone, Alessandro,Wenger, Oliver S.
, p. 609 - 615 (2017/02/05)
Complexes of the type [Ru(bpy)2pyimH]2+[bpy = 2,2′-bipyridine; pyimH = 2-(2-pyridyl)imidazole] with various substituents on the bpy ligands can act as photoreductants. Their reducing power in the ground state and in the long-lived3MLCT excited state is increased significantly upon deprotonation, and they can undergo proton-coupled electron transfer (PCET) in the ground and excited state. PCET with both the proton and electron originating from a single donor resembles hydrogen atom transfer (HAT) and can be described thermodynamically by formal bond dissociation free energies (BDFEs). Whereas the class of complexes studied herein has long been known, their N–H BDFEs have not been determined even though this is important in view of assessing their reactivity. Our study demonstrates that the N–H BDFEs in the3MLCT excited states are between 34 and 52 kcal mol–1depending on the chemical substituents at the bpy spectator ligands. Specifically, we report on the electrochemistry and PCET thermochemistry of three heteroleptic complexes in 1:1 (v/v) CH3CN/H2O with CF3, tBu, and NMe2substituents on the bpy ligands.
Exchange of pyridine and bipyridine ligands in trimethylplatinum(iv) iodide complexes: Substituent and solvent effects
Ghosh, Biswa Nath,Schlecht, Sabine
, p. 101900 - 101909 (2015/12/08)
A series of mononuclear trimethylplatinum(iv) complexes of bipyridine ligands, [PtMe3(L-L)I] (L-L = bipy, 4-Mebipy, 4-MeObipy and 4-Me2Nbipy) has been synthesized by the reaction of trimethylplatinum(iv) iodide with bipyridine ligands L-L in an equimolar ratio. Also, treatment of mononuclear trimethylplatinum(iv) iodide complexes of pyridine ligands, [PtMe3L2I] (L = py, 4-Mepy, 4-MeOpy and 4-Me2Npy) with the corresponding bipyridine ligands leads to the exchange of the pyridines by the bipyridine ligands, thereby resulting in the formation of the more stable chelate bipyridine complexes. The ligand-exchange reactions have been studied by 1H NMR spectroscopy. The 1H NMR spectra of a 1: 1 mixture of mononuclear pyridine complexes [PtMe3L2I] and corresponding bipyridine ligands L-L reveal the formation of two chelate bipyridine complexes, [PtMe3(L-L)I] and [PtMe3(L-L)L]I, in solution. Speciation of the pyridine and bipyridine complexes in solution was found to be dependent on the substituent as well as on the nature of the solvent. Furthermore, crystal structures of three bipyridine complexes [PtMe3(L-L)I] (L-L = 4-Mebipy, 4-MeObipy and 4-Me2Nbipy) have also been investigated here.
