scholarly journals Time-Resolved Infrared Spectroscopy of Binuclear Rhenium (I) Polypyridyl Complexes in Solution

1999 ◽  
Vol 19 (1-4) ◽  
pp. 279-282 ◽  
Author(s):  
L. C. Abbott ◽  
C. J. Arnold ◽  
K. C. Gordon ◽  
R. E. Hester ◽  
J. N. Moore ◽  
...  
Keyword(s):  
Mixed Valence ◽  
Difference Spectra ◽  
Kinetic Measurements ◽  
Time Resolved ◽  
Bridging Ligand ◽  
Ligand Charge Transfer ◽  
Complex Forms ◽  
Time Resolved Infrared Spectroscopy ◽  
State Kinetic ◽  
Mlct State

A series of four binuclear rhenium (I) complexes of the general form [Re(CO)3Cl]2BL, where BL is a polypyridyl bridging ligand, have been studied using ultrafast time-resolved UV/visible (TRVIS) and infrared (TRIR) spectroscopies. Visible excitation produces a metal-to-ligand charge-transfer (MLCT) excited state. Kinetic measurements show that the lifetime of this MLCT state varies between 100 and 1900 ps, depending on the structure of the bridging ligand. TRIR difference spectra show that each complex forms a similar MLCT state which has mixed valence character.

scholarly journals Helmet Phthalocyaninato Iron Complex as a Primary Drier for Alkyd Paints

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1220
Author(s):  
Jan Honzíček ◽  
Eliška Matušková ◽  
Štěpán Voneš ◽  
Jaromír Vinklárek
Keyword(s):  
Catalytic Performance ◽  
Mechanical Tests ◽  
Iron Complex ◽  
Kinetic Measurements ◽  
Time Resolved ◽  
Strong Activity ◽  
Vis Spectroscopy ◽  
Order Of Magnitude ◽  
Transparent Coatings ◽  
Time Resolved Infrared Spectroscopy

This study describes the catalytic performance of an iron(III) complex bearing a phthalocyaninato-like ligand in two solvent-borne and two high-solid alkyd binders. Standardized mechanical tests revealed strong activity, which appeared in particular cases at concentrations about one order of magnitude lower than in the case of cobalt(II) 2-ethylhexanoate, widespread used in paint-producing industry. The effect of the iron(III) compound on autoxidation process, responsible for alkyd curing, was quantified by kinetic measurements by time-resolved infrared spectroscopy and compared with several primary driers. Effect of the drier concentration on coloration of transparent coatings was determined by UV–Vis spectroscopy.

Application of Time-Resolved Infrared Spectroscopy to Electronic Structure in Metal-to-Ligand Charge-Transfer Excited States

2002 ◽  
Vol 41 (23) ◽  
pp. 6071-6079 ◽  
Author(s):  
Dana M. Dattelbaum ◽  
Kristin M. Omberg ◽  
Jon R. Schoonover ◽  
Richard L. Martin ◽  
Thomas J. Meyer
Keyword(s):  
Electronic Structure ◽  
Infrared Spectroscopy ◽  
Charge Transfer ◽  
Excited States ◽  
Time Resolved ◽  
Ligand Charge Transfer ◽  
Time Resolved Infrared Spectroscopy

Art is long and time is fleeting: the current problems and future prospects for time-resolved enzyme crystallography

1992 ◽  
Vol 340 (1657) ◽  
pp. 323-334 ◽  
Keyword(s):  
Enzymatic Reaction ◽  
Site Directed Mutagenesis ◽  
Kinetic Measurements ◽  
Laue Diffraction ◽  
Time Resolved ◽  
X Ray Crystallography ◽  
Time Regime ◽  
Kinetics Of ◽  
State Kinetic

I offer comments on the challenges and problems of the future based on the papers in this volume. First, the requirement of the Laue technique for a very well-ordered crystal is a major obstacle to many studies. Efforts to ease this problem are needed. Secondly, the fundamental issues in time-resolved crystallography are now chemical rather than crystallographic. Methods for the rapid initiation of many reactions must be developed. Thirdly, it is imperative that the kinetics of the process in question be studied in the crystal before any diffraction experiments are done. We need better ways to make those solid state kinetic measurements. Fourthly, we should make use of combined methods, such as cryoenzymology plus Laue diffraction or site-directed mutagenesis plus Laue diffraction, to bring many processes into the time regime in which we currently can work. Fifthly, we have to be able to deconvolute diffraction data that come from a mixture of two or three discrete species. Finally, no matter how powerful our synchrotrons get, it seems to me that some of the most important events in any enzymatic reaction are not going to be accessible: consider the formation and decomposition of a transition state as an example. I close by discussing the role of computational biochemistry in filling in those frames of our enzymatic movie that we cannot observe directly by time-resolved X-ray crystallography.

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 quantum cascade laser setup for studying irreversible photoreactions in H2O with nanosecond resolution and microlitre consumption

2020 ◽  
Vol 22 (45) ◽  
pp. 26459-26467
Author(s):  
Jessica L. Klocke ◽  
Tilman Kottke
Keyword(s):  
Infrared Spectroscopy ◽  
Quantum Cascade Laser ◽  
Time Resolved ◽  
Quantum Cascade ◽  
Time Resolved Infrared Spectroscopy ◽  
Laser Setup

Flavin photoreduction in H2O is elucidated by developing a quantum cascade laser setup for time-resolved infrared spectroscopy on irreversible reactions.

Water Transport in Proton Exchange Membranes: Insights from Time-Resolved Infrared Spectroscopy

2019 ◽  
Vol 33 (1) ◽  
pp. 1029-1033 ◽  
Author(s):  
Daniel Hallinan ◽  
Maria Grazia De Angelis ◽  
Marco Giacinti Baschetti ◽  
Giulio Sarti ◽  
Yossef A. Elabd
Keyword(s):  
Infrared Spectroscopy ◽  
Water Transport ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Time Resolved ◽  
Time Resolved Infrared Spectroscopy

scholarly journals Time-resolved observation of protein allosteric communication

2017 ◽  
Vol 114 (33) ◽  
pp. E6804-E6811 ◽  
Author(s):  
Sebastian Buchenberg ◽  
Florian Sittel ◽  
Gerhard Stock
Keyword(s):  
Pdz Domain ◽  
Dynamic Network ◽  
Structural Heterogeneity ◽  
Nonequilibrium Molecular Dynamics ◽  
Elastic Response ◽  
Dynamical Process ◽  
Biological Regulation ◽  
Time Resolved ◽  
Allosteric Communication ◽  
Time Resolved Infrared Spectroscopy

Allostery represents a fundamental mechanism of biological regulation that is mediated via long-range communication between distant protein sites. Although little is known about the underlying dynamical process, recent time-resolved infrared spectroscopy experiments on a photoswitchable PDZ domain (PDZ2S) have indicated that the allosteric transition occurs on multiple timescales. Here, using extensive nonequilibrium molecular dynamics simulations, a time-dependent picture of the allosteric communication in PDZ2S is developed. The simulations reveal that allostery amounts to the propagation of structural and dynamical changes that are genuinely nonlinear and can occur in a nonlocal fashion. A dynamic network model is constructed that illustrates the hierarchy and exceeding structural heterogeneity of the process. In compelling agreement with experiment, three physically distinct phases of the time evolution are identified, describing elastic response (≲0.1 ns), inelastic reorganization (∼100 ns), and structural relaxation (≳1μs). Issues such as the similarity to downhill folding as well as the interpretation of allosteric pathways are discussed.

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