Luminescence of a New Ru(II) Polypyridine Complex Controlled by a Redox-Responsive Protonable Anthra[1,10]phenanthrolinequinone

2005 ◽  
Vol 70 (11) ◽  
pp. 1891-1908 ◽  
Author(s):  
František Hartl ◽  
Sandrine Vernier ◽  
Peter Belser
Keyword(s):  
Charge Transfer ◽  
Quantum Yield ◽  
Emission Intensity ◽  
Luminescence Quenching ◽  
Luminescence Quantum Yield ◽  
Ligand Charge Transfer ◽  
Redox Responsive ◽  
Electron Reduction ◽  
Mlct State

Redox-controlled luminescence quenching is presented for a new Ru(II)-bipyridine complex [Ru(bpy)2(1)]2+ where ligand 1 is an anthra[1,10]phenanthrolinequinone. The complex emits from a short-lived metal-to-ligand charge transfer, 3MLCT state (τ = 5.5 ns in deaerated acetonitrile) with a low luminescence quantum yield (5 × 10-4). The emission intensity becomes significantly enhanced when the switchable anthraquinone unit is reduced to corresponding hydroquinone. On the contrary, chemical one-electron reduction of the anthraquinone moiety to semiquinone in aprotic tetrahydrofuran results in total quenching of the emission.

Isolation of a metal-to-ligand charge-transfer (MLCT) state of a tris 1,4-diimine complex of iron in the solid state: X-ray crystal structure and EPR

2017 ◽  
Vol 41 (2) ◽  
pp. 452-456 ◽  
Author(s):  
Nirmal K. Shee ◽  
Michael G. B. Drew ◽  
Dipankar Datta
Keyword(s):  
Crystal Structure ◽  
Charge Transfer ◽  
Solid State ◽  
X Ray ◽  
Ligand Charge Transfer ◽  
Mlct State

Using 5,6-dihydro-5,6-epoxy-1,10-phenanthroline as the ligand L, the X-ray crystal structure of [FeL3](ClO4)2·2H2O is determined.

scholarly journals Gold nanoclusters with bright near-infrared photoluminescence

Nanoscale ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 3792-3798 ◽  
Author(s):  
Goutam Pramanik ◽  
Jana Humpolickova ◽  
Jan Valenta ◽  
Paromita Kundu ◽  
Sara Bals ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Quantum Yield ◽  
Near Infrared ◽  
Gold Nanoclusters ◽  
Ligand Charge Transfer

Triphenylphosphonium cations strongly enhance the PL quantum yield of the near infrared photoluminescent gold nanoclusters by metal-to-ligand charge transfer.

scholarly journals Square-Planar Heteroleptic Complexes of α-Diimine-NiII-Catecholate Type: Intramolecular Ligand-to-Ligand Charge Transfer

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4622
Author(s):  
Kira I. Pashanova ◽  
Vladlena O. Bitkina ◽  
Ilya A. Yakushev ◽  
Maxim V. Arsenyev ◽  
Alexandr V. Piskunov
Keyword(s):  
Charge Transfer ◽  
Molecular Design ◽  
Crystal Packing ◽  
Molecular Geometry ◽  
Lamellar Crystal ◽  
Heteroleptic Complexes ◽  
Redox Active ◽  
Ligand Charge Transfer ◽  
Square Planar ◽  
Electron Reduction

Two heteroleptic NiII complexes combined the redox-active catecholate and 2,2′- bipyridine ligand platforms were synthesized to observe a photoinduced intramolecular ligand-to-ligand charge transfer (LL’CT, HOMOcatecholate → LUMOα-diimine). A molecular design of compound [NiII(3,6-Cat)(bipy)]∙CH3CN (1) on the base of bulky 3,6-di-tert-butyl-o-benzoquinone (3,6-DTBQ) was an annelation of the ligand with an electron donor glycol fragment, producing derivative [NiII(3,6-Catgly)(bipy)]∙CH2Cl2 (2), in order to influence the energy of LL’CT transition. A substantial longwave shift of the absorption peak was observed in the UV-Vis-NIR spectra of 2 compared with those in 1. In addition, the studied NiII derivatives demonstrated a pronounced negative solvatochromism, which was established using a broad set of solvents. The molecular geometry of both compounds can be ascribed as an insignificantly distorted square-planar type, and the π–π intermolecular stacking of the neighboring α-diimines is realized in a crystal packing. There is a lamellar crystal structure for complex 1, whereas the perpendicular T-motifs with the inter-stacks attractive π–π interactions form the packing of complex 2. The redox-active nature of ligand systems was clearly shown through the electrochemical study: a quasi-reversible one-electron reduction of 2,2′-bipyridine and two reversible successive one-electron oxidative conversations (“catecholate dianion—o-benzosemiquinonato radical anion—neutral o-benzoquinone”) were detected.

scholarly journals Controlling the Lifetime of the Triplet MLCT State in Fe(II) Polypyridyl Complexes through Ligand Modification

Inorganics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 16 ◽  
Author(s):  
Jianfang Wu ◽  
Marc Alías ◽  
Coen de Graaf
Keyword(s):  
Charge Transfer ◽  
Field Strength ◽  
Computational Study ◽  
Relative Energy ◽  
Ligand Field ◽  
Polypyridyl Complexes ◽  
Ligand Modification ◽  
Ligand Charge Transfer ◽  
Mlct State

A computational study is presented in which two strategies of ligand modifications have been explored to invert the relative energy of the metal-to-ligand charge transfer (MLCT) and metal-centered (MC) state in Fe(II)-polypyridyl complexes. Replacing the bipyridines by stronger σ donors increases the ligand-field strength and pushes the MC state to higher energy, while the use of ligands with a larger π conjugation leads to lower MLCT energies.

Synthesis and Photochemical Properties of Re(I) Tricarbonyl Complexes Bound to Thione and Thiazole-2-ylidene Ligands

2020 ◽  
Author(s):  
Matthew Stout ◽  
Brian Skelton ◽  
Alexandre N. Sobolev ◽  
Paolo Raiteri ◽  
Massimiliano Massi ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Excited States ◽  
Ligand Exchange ◽  
Ligand Substitution ◽  
Bidentate Ligand ◽  
The Other ◽  
Ligand Exchange Reaction ◽  
Multiple Products ◽  
Ligand Charge Transfer ◽  
Photochemical Properties

<p>Three Re(I) tricarbonyl complexes, with general formulation Re(N^L)(CO)<sub>3</sub>X (where N^L is a bidentate ligand containing a pyridine functionalized in the position 2 with a thione or a thiazol-2-ylidene group and X is either chloro or bromo) were synthesized and their reactivity explored in terms of solvent-dependent ligand substitution, both in the ground and excited states. When dissolved in acetonitrile, the complexes bound to the thione ligand underwent ligand exchange with the solvent resulting in the formation of Re(NCMe)<sub>2</sub>(CO)<sub>3</sub>X. The exchange was found to be reversible, and the starting complex was reformed upon removal of the solvent. On the other hand, the complexes appeared inert in dichloromethane or acetone. Conversely, the complex bound to the thiazole-2-ylidene ligand did not display any ligand exchange reaction in the dark, but underwent photoactivated ligand substitution when excited to its lowest metal-to-ligand charge transfer manifold. Photolysis of this complex in acetonitrile generated multiple products, including Re(I) tricarbonyl and dicarbonyl solvato-complexes as well as free thiazole-2-ylidene ligand.</p>

scholarly journals Tuning π-Acceptor/σ-Donor Ratio of the 2-Isocyanoazulene Ligand: Non-Fluorinated Rival of Pentafluorophenyl Isocyanide and Trifluorovinyl Isocyanide Discovered

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 981
Author(s):  
Mason D. Hart ◽  
John J. Meyers ◽  
Zachary A. Wood ◽  
Toshinori Nakakita ◽  
Jason C. Applegate ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Coordination Chemistry ◽  
Single Crystal ◽  
13C Nmr ◽  
Quantitative Assessment ◽  
X Ray ◽  
New Class ◽  
Linear Relationships ◽  
Ligand Charge Transfer ◽  
Donor Characteristics

Isocyanoazulenes (CNAz) constitute a relatively new class of isocyanoarenes that offers rich structural and electronic diversification of the organic isocyanide ligand platform. This article considers a series of 2-isocyano-1,3-X2-azulene ligands (X = H, Me, CO2Et, Br, and CN) and the corresponding zero-valent complexes thereof, [(OC)5Cr(2-isocyano-1,3-X2-azulene)]. Air- and thermally stable, X-ray structurally characterized 2-isocyano-1,3-dimethylazulene may be viewed as a non-benzenoid aromatic congener of 2,6-dimethyphenyl isocyanide (2,6-xylyl isocyanide), a longtime “workhorse” aryl isocyanide ligand in coordination chemistry. Single crystal X-ray crystallographic {Cr–CNAz bond distances}, cyclic voltametric {E1/2(Cr0/1+)}, 13C NMR {δ(13CN), δ(13CO)}, UV-vis {dπ(Cr) → pπ*(CNAz) Metal-to-Ligand Charge Transfer}, and FTIR {νN≡C, νC≡O, kC≡O} analyses of the [(OC)5Cr(2-isocyano-1,3-X2-azulene)] complexes provided a multifaceted, quantitative assessment of the π-acceptor/σ-donor characteristics of the above five 2-isocyanoazulenes. In particular, the following inverse linear relationships were documented: δ(13COtrans) vs. δ(13CN), δ(13COcis) vs. δ(13CN), and δ(13COtrans) vs. kC≡O,trans force constant. Remarkably, the net electron withdrawing capability of the 2-isocyano-1,3-dicyanoazulene ligand rivals those of perfluorinated isocyanides CNC6F5 and CNC2F3.

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