An Unusual Dinuclear Ruthenium(III) Complex with a Conjugated Bridging Ligand Derived from Cleavage of a 1,4-Dihydro-1,2,4,5-Tetrazine Ring. Synthesis, Structure, and UV−Vis−NIR Spectroelectrochemical Characterization of a Five-Membered Redox Chain Incorporating Two Mixed-Valence States

2003 ◽  
Vol 42 (15) ◽  
pp. 4707-4713 ◽  
Author(s):  
Srikanta Patra ◽  
Thomas A. Miller ◽  
Biprajit Sarkar ◽  
Mark Niemeyer ◽  
Michael D. Ward ◽  
...  
2014 ◽  
Vol 33 (18) ◽  
pp. 4893-4904 ◽  
Author(s):  
Takumi Nagashima ◽  
Takuya Nakabayashi ◽  
Takashi Suzuki ◽  
Katsuhiko Kanaizuka ◽  
Hiroaki Ozawa ◽  
...  

2005 ◽  
Vol 58 (11) ◽  
pp. 767 ◽  
Author(s):  
Deanna M. D'Alessandro ◽  
F. Richard Keene

The degree of delocalization in the symmetrical complexes [{Ru(bpy)2}2(μ-dpb′)]5+ and [{Ru(bpy)2}2(μ-dpb)]5+ (dpb = 2,3-bis(2-pyridyl)-1,4-benzoquinoxaline; dpb′ = dipyrido(2,3-a;3′,2′-c)benzophenazine; bpy = 2,2′-bipyridine) is diminished by the substitution of the terminal bpy ligands at one end of the complex. The results of a classical analysis for the diastereoisomeric forms of the series of complexes [{Ru(bpy)2}(μ-BL){Ru(pp)2}]5+ (pp = bpy, Me2bpy (4,4′-dimethyl-2,2′-bipyridine), Me4bpy (4,4′,5,5′-tetramethyl-2,2′-bipyridine)) indicate that a greater degree of ground-state delocalization exists in the complexes incorporating the bridging ligand dpb′ compared with the dpb analogue. A two-state analysis in which ΔE 0 (the redox asymmetry) is varied at constant H ab (the electronic coupling) and λ (the reorganizational energy) does not adequately describe the properties of the systems due to the importance of a third electronic state corresponding to the bridging ligand.


2013 ◽  
Vol 52 (9) ◽  
pp. 5507-5514 ◽  
Author(s):  
Misaki Makino ◽  
Tomoya Ishizuka ◽  
Shingo Ohzu ◽  
Jiang Hua ◽  
Hiroaki Kotani ◽  
...  

2014 ◽  
Vol 92 (11) ◽  
pp. 1081-1085 ◽  
Author(s):  
Fatemeh Habibagahi ◽  
Robert J. Crutchley

The novel bridging ligand 3,6-bis(phenylcyanamido)-1,2,4,5-tetrazine (tdpcH2) and its dinuclear complex [{Ru(ttpy)(bpy)}2(μ-tdpc)][PF6]2 were prepared and characterized by elemental analysis and 1H NMR spectroscopy. Cyclic voltammetry and vis-NIR and IR spectroelectrochemistry of [{Ru(ttpy)(bpy)}2(μ-tdpc)]2+ showed that [{Ru(ttpy)(bpy)}2(μ-tdpc)]3+ is a Class II mixed-valence system with metal−metal coupling of 400 cm−1 assuming a transition dipole moment length of 21 Å. DFT calculations of tdpc2− suggested that the stability of the HOMO results in weak metal−metal coupling via the hole-superexchange mechanism.


2021 ◽  
pp. 088532822110134
Author(s):  
Sushant Singh ◽  
Udit Kumar ◽  
David Gittess ◽  
Tamil S Sakthivel ◽  
Balaashwin Babu ◽  
...  

Many studies have linked reactive oxygen species (ROS) to various diseases. Biomedical research has therefore sought a way to control and regulate ROS produced in biological systems. In recent years, cerium oxide nanoparticles (nanoceria, CNPs) have been pursued due to their ability to act as regenerative ROS scavengers. In particular, they are shown to have either superoxide dismutase (SOD) or catalase mimetic (CAT) potential depending on the ratio of Ce3+/Ce4+ valence states. Moreover, it has been demonstrated that SOD mimetic activity can be diminished by the presence of phosphate, which can be a problem given that many biological systems operate in a phosphate-rich environment. Herein, we report a CNP formulation with both SOD and catalase mimetic activity that is preserved in a phosphate-rich media. Characterization demonstrated a highly dispersed, stable solution of uniform-sized, spherical-elliptical shaped CNP of 12 ± 2 nm, as determined through dynamic light scattering, zeta potential, and transmission electron microscopy. Mixed valence states of Ce ions were observed via UV/Visible spectroscopy and XPS (Ce3+/Ce4+ > 1) (Ce3+∼ 62%). X-ray diffraction and XPS confirmed the presence of oxygen-deficient cerium oxide (CeO2-x) particles. Finally, the CNP demonstrated very good biocompatibility and efficient reduction of hydrogen peroxide under in-vitro conditions.


2021 ◽  
Vol 60 (3) ◽  
pp. 1806-1813
Author(s):  
Husain N. Kagalwala ◽  
Mahesh S. Deshmukh ◽  
Elamparuthi Ramasamy ◽  
Neelima Nair ◽  
Rongwei Zhou ◽  
...  

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