Structure of the Photochemical Reaction Path Populated via Promotion of CF<sub>2</sub>I<sub>2</sub> into Its First Excited State

El‐Khoury, Patrick Z.; Tarnovsky, Alexander N.; Schapiro, Igor; Ryazantsev, Mikhail N.; Olivucci, Massimo

doi:10.1021/jp902873h

Cited by 20 publications

(8 citation statements)

References 30 publications

(108 reference statements)

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“…CF 2 I van der Waals complex, which is thought to be constrained by a solvent cage and subsequently collapses into iso-CF 2 I 2 , an isomer of CF 2 I 2 . 40 This is consistent with the previous MP2 calculations, which provided computational evidence for the existence of a ground-state potential energy minimum corresponding to iso-CF 2 I 2 . 41 Furthermore, MP2 calculations suggest that the formation of CF 2 +I 2 is the lowest energy dissociation channel of iso-CF 2 I 2 , whereas the formation of the CF 2 I + I radical pair requires considerably more energy, 41 unlike ground-state iso-CH 2 I 2 .…”

Section: Introductionsupporting

confidence: 92%

Characterization of iso-CF2I2 in frequency and ultrafast time domains

El‐Khoury

George

Kalume

et al. 2010

The Journal of Chemical Physics

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The photolysis of diiododifluoromethane (CF(2)I(2)) in condensed phases was studied by a combination of matrix isolation and ultrafast time-resolved spectroscopy, in concert with ab initio calculations. Photolysis at wavelengths of 355 or 266 nm of CF(2)I(2):Ar samples (1:5000) held at approximately 8 K yielded iso-CF(2)I(2) (F(2)C-I-I), a metastable isomer of CF(2)I(2), characterized here for the first time. The infrared (IR) spectra of this isomer were recorded in matrix experiments, and the derived positions of the C-F stretching modes are in very good agreement with the predictions of high level ab initio calculations, which show that the iso-form is a minimum on the CF(2)I(2) ground state potential energy surface. The formation of this isomer following 350 nm excitation of CF(2)I(2) in room temperature CCl(4) solutions was monitored through its intense C-F stretching mode by means of ultrafast time-resolved IR absorption. Together, matrix isolation and ultrafast IR absorption experiments suggest that the formation of iso-CF(2)I(2) occurs via recombination of CF(2)I radical and I atom. Ultrafast IR experiments detect a delayed rise of iso-CF(2)I-I absorption, placing an upper limit of 400 fs for the C-I bond dissociation and primary geminate recombination processes. The product absorption spectrum recorded 1 ns after 350 nm excitation of CF(2)I(2) in solution is virtually identical to the visible absorption spectrum of iso-CF(2)I(2) trapped in matrix isolation experiments [with subtracted I(2)(X) absorption]. The formation of this isomer in solution at room temperature has direct dynamic implications for the ultrafast production of molecular iodine from electronically excited CF(2)I(2).

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Section: Introductionsupporting

confidence: 92%

Characterization of iso-CF2I2 in frequency and ultrafast time domains

El‐Khoury

George

Kalume

et al. 2010

The Journal of Chemical Physics

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“…In general, the electronic absorption spectra of metal complexes reveal intense LMCT bands in the UV-vis region as well as absorption bands located at longer wavelengths (including near-IR range) assigned to d-d transitions. The excitation to the d-d states does not induce the photoreaction, whereas the LMCT excited states are dissociative and lead to the reduction of metal complex followed by formation of metallic structures [ 29 , 30 , 31 , 32 ]. In turn, the 532 nm excitation used in the current work does not populate the photochemically active LMCT states of 1, 2 and 3 ( Figure 1 ) meaning that in our case we observe thermo-induced metal reduction process.…”

Section: Resultsmentioning

confidence: 99%

Laser-Induced Synthesis of Composite Materials Based on Iridium, Gold and Platinum for Non-Enzymatic Glucose Sensing

et al. 2020

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A simple approach for in situ laser-induced modification of iridium-based materials to increase their electrocatalytic activity towards enzyme-free glucose sensing was proposed. For this purpose, we deposited gold and platinum separately and as a mixture on the surface of pre-synthesized iridium microstructures upon laser irradiation at a wavelength of 532 nm. Then, we carried out the comparative investigation of their morphology, elemental and phase composition as well as their electrochemical properties. The best morphology and, as a result, the highest sensitivity (~9960 µA/mM cm2) with respect to non-enzymatic determination of D-glucose were demonstrated by iridium-gold-platinum microstructures also showing low limit of detection (~0.12 µM), a wide linear range (0.5 µM–1 mM) along with good selectivity, reproducibility and stability.

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“…For example, the homology modeling is an important step towards a more effective automatic construction of QM/MM models (e.g., as a recently proposed ARM protocol). 36 Thus, the selection of effective homology modeling methods together with the further development of suitable QM/MM methods can facilitate, via rational design or random mutation methods, the achievement of new rhodopsin-based tools for the mentioned technologies. Moreover, the results of our benchmark may be extended to other classes of membrane proteins, such as GPCRs, which are also extensively studied nowadays.…”

Section: Discussionmentioning

confidence: 99%

A Comparative Study of Modern Homology Modeling Algorithms for Rhodopsin Structure Prediction

et al. 2018

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Rhodopsins are seven α-helical membrane proteins that are of great importance in chemistry, biology, and modern biotechnology. Any in silico study on rhodopsin properties and functioning requires a high-quality three-dimensional structure. Due to particular difficulties with obtaining membrane protein structures from the experiment, in silico prediction of the three-dimensional rhodopsin structure based only on its primary sequence is an especially important task. For the last few years, significant progress was made in the field of protein structure prediction, especially for methods based on comparative modeling. However, the majority of this progress was made for soluble proteins and further investigations are needed to achieve similar progress for membrane proteins. In this paper, we evaluate the performance of modern protein structure prediction methodologies (implemented in the Medeller, I-TASSER, and Rosetta packages) for their ability to predict rhodopsin structures. Three widely used methodologies were considered: two general methodologies that are commonly applied to soluble proteins and a methodology that uses constraints that are specific for membrane proteins. The test pool consisted of 36 target-template pairs with different sequence similarities that was constructed on the basis of 24 experimental rhodopsin structures taken from the RCSB database. As a result, we showed that all three considered methodologies allow obtaining rhodopsin structures with the quality that is close to the crystallographic one (root mean square deviation (RMSD) of the predicted structure from the corresponding X-ray structure up to 1.5 Å) if the target-template sequence identity is higher than 40%. Moreover, all considered methodologies provided structures of average quality (RMSD < 4.0 Å) if the target-template sequence identity is higher than 20%. Such structures can be subsequently used for further investigation of molecular mechanisms of protein functioning and for the development of modern protein-based biotechnologies.

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Structure of the Photochemical Reaction Path Populated via Promotion of CF₂I₂ into Its First Excited State

Cited by 20 publications

References 30 publications

Characterization of iso-CF2I2 in frequency and ultrafast time domains

Characterization of iso-CF2I2 in frequency and ultrafast time domains

Laser-Induced Synthesis of Composite Materials Based on Iridium, Gold and Platinum for Non-Enzymatic Glucose Sensing

A Comparative Study of Modern Homology Modeling Algorithms for Rhodopsin Structure Prediction

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Structure of the Photochemical Reaction Path Populated via Promotion of CF2I2 into Its First Excited State

Cited by 20 publications

References 30 publications

Characterization of iso-CF2I2 in frequency and ultrafast time domains

Characterization of iso-CF2I2 in frequency and ultrafast time domains

Laser-Induced Synthesis of Composite Materials Based on Iridium, Gold and Platinum for Non-Enzymatic Glucose Sensing

A Comparative Study of Modern Homology Modeling Algorithms for Rhodopsin Structure Prediction

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Structure of the Photochemical Reaction Path Populated via Promotion of CF₂I₂ into Its First Excited State