Wavelength dependence and solvent effects on the ligand field photochemistry: the ring closure process in the excited [Fe(CN)5(tn)]3− complex

1996 ◽  
Vol 74 (4) ◽  
pp. 476-480 ◽  
Author(s):  
Jailson Farias De Lima ◽  
Neyde Yukie Murakami Iha
Keyword(s):  
Excited States ◽  
Complex Function ◽  
Sharp Decrease ◽  
Wavelength Dependence ◽  
Ring Closure ◽  
Quantum Yields ◽  
Ligand Field ◽  
Solvent Cage ◽  
Water Glycerol ◽  
Medium Viscosity

The solvent composition and wavelength effects on the quantum yield of the photoinduced ring closure process of the [Fe(CN)5(tn)]3− complex (tn = 1,3-diaminopropane) were investigated. The reactivity was shown to be controlled by the macroscopic properties of water–glycerol mixtures. A sharp decrease in quantum yields with increasing medium viscosity was observed for all the irradiation wavelengths employed (313, 334, 365, 404, and 434 nm). The observed quantum yields ranged from 0.24 (λirr = 313 nm, 66.48 wt.% of acetonitrile) to 0.010 (λirr = 404 or 434 nm, 61.85 wt.% of glycerol). The overall efficiency is a complex function of the dynamics of radical recombination and dissociation pathways. The proposed cage model for the deactivation dynamics of the excited states illustrates that the decrease in medium viscosity favors a diffusional escape of the cyanide from the solvent cage. Key words: photochemistry, pentacyanoferrate(II) complexes, solvent effect, wavelength effect.

Ligand Field Photochemistry of Cobalt(III) Phenanthroline and Bipyridyl Complexes

1975 ◽  
Vol 53 (20) ◽  
pp. 3121-3127 ◽  
Author(s):  
Carol P. J. Vuik ◽  
Noel A. P. Kane-Maguire ◽  
Cooper H. Langford
Keyword(s):  
Excited States ◽  
Quantum Yields ◽  
Ligand Field

The ligand field photochemistry of Cophen2C2O4+, Cobipy2C2O4+, and of Cophen33+ in the presence of added oxalate has been investigated. In all cases reduction to cobalt(II) complexes occurs with moderate quantum yields (>0.01). The nature of the reactive excited states is discussed, as is the mechanism of the Cophen33+–oxalate photoreaction.

The Character of Low-Lying Excited States of Mixed-Ligand Metal Carbonyls. TD-DFT and CASSCF/CASPT2 Study of [W(CO)4L] (L = ethylenediamine, N,N'-dialkyl-1,4-diazabutadiene) and [W(CO)5L] (L = pyridine, 4-cyanopyridine)

2003 ◽  
Vol 68 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Stanislav Záliš ◽  
Antonín Vlček ◽  
Chantal Daniel
Keyword(s):  
Excited States ◽  
Substitution Effect ◽  
Electronic Transitions ◽  
Ligand Field ◽  
Metal Carbonyls ◽  
Electron Density Redistribution ◽  
Time Resolved ◽  
Model Complex ◽  
Td Dft ◽  
Time Resolved Infrared Spectroscopy

This contribution presents the results of the TD-DFT and CASSCF/CASPT2 calculations on [W(CO)4(MeDAB)] (MeDAB = N,N'-dimethyl-1,4-diazabutadiene), [W(CO)4(en)] (en = ethylenediamine), [W(CO)5(py)] (py = pyridine) and [W(CO)5(CNpy)] (CNpy = 4-cyanopyridine) complexes. Contrary to the textbook interpretation, calculations on the model complex [W(CO)4(MeDAB)] and [W(CO)5(CNpy)] show that the lowest W→MeDAB and W→CNpy MLCT excited states are immediately followed in energy by several W→CO MLCT states, instead of ligand-field (LF) states. The lowest-lying excited states of [W(CO)4(en)] system were characterized as W(COeq)2→COax CT excitations, which involve a remarkable electron density redistribution between axial and equatorial CO ligands. [W(CO)5(py)] possesses closely-lying W→CO and W→py MLCT excited states. The calculated energies of these states are sensitive to the computational methodology used and can be easily influenced by a substitution effect. The calculated shifts of [W(CO)4(en)] stretching CO frequencies due to excitation are in agreement with picosecond time-resolved infrared spectroscopy experiments and confirm the occurrence of low-lying M→CO MLCT transitions. No LF electronic transitions were found for either of the complexes studied in the region up to 4 eV.

A ligand field theory-based methodology for the characterization of the Eu 2+ [Xe]4f 6 5d 1 excited states in solid state compounds

2015 ◽  
Vol 622 ◽  
pp. 120-123 ◽  
Author(s):  
Amador García-Fuente ◽  
Fanica Cimpoesu ◽  
Harry Ramanantoanina ◽  
Benjamin Herden ◽  
Claude Daul ◽  
...  
Keyword(s):  
Field Theory ◽  
Solid State ◽  
Excited States ◽  
Ligand Field ◽  
Ligand Field Theory ◽  
The Eu

Strongly Luminescent Gold(III) Complexes with Long-Lived Excited States: High Emission Quantum Yields, Energy Up-Conversion, and Nonlinear Optical Properties

2013 ◽  
Vol 52 (26) ◽  
pp. 6648-6652 ◽  
Author(s):  
Wai-Pong To ◽  
Kaai Tung Chan ◽  
Glenna So Ming Tong ◽  
Chensheng Ma ◽  
Wai-Ming Kwok ◽  
...  
Keyword(s):  
Optical Properties ◽  
Excited States ◽  
Nonlinear Optical ◽  
Nonlinear Optical Properties ◽  
Quantum Yields ◽  
High Emission

scholarly journals Synthesis, Characterization and Photophysical Properties of a New 2,5-Di(aryl)phosphole Derivative and Their Trigonal Copper-Phosphole Complexes

2020 ◽  
Author(s):  
Neskarlys Rios ◽  
Franmerly Fuentes ◽  
Juan Manuel Garcia Garfido ◽  
Yomaira Otero
Keyword(s):  
Field Strength ◽  
Fluorescence Spectroscopy ◽  
Photophysical Properties ◽  
High Yield ◽  
Quantum Yields ◽  
Ligand Field ◽  
Emission Energy ◽  
Esi Ms

<div>A new phosphole derivative 2,5-di(2-quinolyl)-1-phenylphosphole (<b>1</b>) was synthesized by using the Fagan-Nugent method. Phosphole was obtained as an air stable solid in high yield (73%). Additionally, two new copper phosphole complexes [CuX(Phosphole)<sub>2</sub>] (X = Cl (<b>2a</b>), I (<b>2b</b>), Phosphole = <b>1</b>) have been synthesized by reaction of CuX (X = Cl, I) and phosphole derivative (<b>1</b>). All compound were characterized by NMR, ESI-MS, UV–Vis and fluorescence spectroscopy. The photophysical properties of all compounds were analyzed, UV-Vis spectra of the complexes <b>2a-b</b> shown π–π* transitions with shift very similar to the found in the free phosphole due to that their symmetrical structures inhibits efficient ILCT. We have found that the compounds <b>1</b>, <b>2a-b</b> exhibited fluorescence between 460 and 583 nm with quantum yields of Φ<sub>f</sub> = 0.04 – 0.11. The emission energy of <b>2b</b> is higher than <b>2a</b>, suggesting that λ<sub>max</sub> is affected by the ligand-field strength of the halogen ions in the complexes (I<sup>-</sup> < Cl<sup>-</sup> ).</div>

scholarly journals Synthesis, Characterization and Photophysical Properties of a New 2,5-Di(aryl)phosphole Derivative and Their Trigonal Copper-Phosphole Complexes

2020 ◽  
Author(s):  
Neskarlys Rios ◽  
Franmerly Fuentes ◽  
Juan Manuel Garcia Garfido ◽  
Yomaira Otero
Keyword(s):  
Field Strength ◽  
Fluorescence Spectroscopy ◽  
Photophysical Properties ◽  
High Yield ◽  
Quantum Yields ◽  
Ligand Field ◽  
Emission Energy ◽  
Esi Ms

<div>A new phosphole derivative 2,5-di(2-quinolyl)-1-phenylphosphole (<b>1</b>) was synthesized by using the Fagan-Nugent method. Phosphole was obtained as an air stable solid in high yield (73%). Additionally, two new copper phosphole complexes [CuX(Phosphole)<sub>2</sub>] (X = Cl (<b>2a</b>), I (<b>2b</b>), Phosphole = <b>1</b>) have been synthesized by reaction of CuX (X = Cl, I) and phosphole derivative (<b>1</b>). All compound were characterized by NMR, ESI-MS, UV–Vis and fluorescence spectroscopy. The photophysical properties of all compounds were analyzed, UV-Vis spectra of the complexes <b>2a-b</b> shown π–π* transitions with shift very similar to the found in the free phosphole due to that their symmetrical structures inhibits efficient ILCT. We have found that the compounds <b>1</b>, <b>2a-b</b> exhibited fluorescence between 460 and 583 nm with quantum yields of Φ<sub>f</sub> = 0.04 – 0.11. The emission energy of <b>2b</b> is higher than <b>2a</b>, suggesting that λ<sub>max</sub> is affected by the ligand-field strength of the halogen ions in the complexes (I<sup>-</sup> < Cl<sup>-</sup> ).</div>

scholarly journals Ligand Field Effects on the Ground and Excited States of the Catalytically Active FeO2+ Species

2018 ◽  
Author(s):  
Justin K. Kirkland ◽  
Shahriar N. Khan ◽  
Bryan Casale ◽  
Evangelos Miliordos ◽  
Konstantinos Vogiatzis
Keyword(s):  
Excited States ◽  
Function Theory ◽  
Weak Field ◽  
Ligand Field ◽  
Model Complexes ◽  
Coordination Environment ◽  
Reactivity Descriptors ◽  
Field Effects ◽  
Catalytically Active ◽  
High Level

<p>We have performed high-level wave function theory calculations on bare FeO2+ and a series of non-heme Fe(IV)-oxo model complexes in order to elucidate the electronic properties and the ligand field effects on those channels. Our results suggest that a coordination environment formed by a weak field gives access to both competitive channels, yielding more reactive Fe(IV)-oxo sites. On the contrary, a strong ligand environment stabilizes only the σ-channel. Our concluding remarks will aid on the derivation of new structure-reactivity descriptors that can contribute on the development of the next generation of functional catalysts.</p>

scholarly journals Ligand Field Effects on the Ground and Excited States of the Catalytically Active FeO2+ Species

2018 ◽  
Author(s):  
Justin K. Kirkland ◽  
Shahriar N. Khan ◽  
Bryan Casale ◽  
Evangelos Miliordos ◽  
Konstantinos Vogiatzis
Keyword(s):  
Excited States ◽  
Function Theory ◽  
Weak Field ◽  
Ligand Field ◽  
Model Complexes ◽  
Coordination Environment ◽  
Reactivity Descriptors ◽  
Field Effects ◽  
Catalytically Active ◽  
High Level

<p>We have performed high-level wave function theory calculations on bare FeO2+ and a series of non-heme Fe(IV)-oxo model complexes in order to elucidate the electronic properties and the ligand field effects on those channels. Our results suggest that a coordination environment formed by a weak field gives access to both competitive channels, yielding more reactive Fe(IV)-oxo sites. On the contrary, a strong ligand environment stabilizes only the σ-channel. Our concluding remarks will aid on the derivation of new structure-reactivity descriptors that can contribute on the development of the next generation of functional catalysts.</p>

Additions and Corrections - Reaction Dynamics and Hydroxide Ion Quenching of Rhodium(III) Ligand Field Excited States. Photoreactions of Rh(NH3)5I2+.

1984 ◽  
Vol 23 (17) ◽  
pp. 2728-2728
Author(s):  
Mark Frink ◽  
Douglas Magde ◽  
Douglas Sexton ◽  
Peter Ford
Keyword(s):  
Excited States ◽  
Reaction Dynamics ◽  
Ligand Field ◽  
Hydroxide Ion
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