scholarly journals On the Relationship Between Hydrogen-Bonding Motifs and the 1b1 Splitting in the X-ray Emission Spectrum of Liquid Water

2020 ◽  
Author(s):  
Vinicius Cruzeiro ◽  
Andrew Wildman ◽  
Xiasong Li ◽  
Francesco Paesani
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Water ◽  
Density Functional ◽  
Potential Energy Function ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Systematic Analysis ◽  
X Ray ◽  
Td Dft ◽  
The Relationship

The split of the 1<i>b</i><sub>1</sub> peak observed in the X-ray emission (XE) spectrum of liquid water has been the focus of intense research over the last two decades. Although several hypotheses have been proposed to explain the origin of the 1<i>b</i><sub>1</sub> splitting, a general consensus has not yet been reached. In this study, we introduce a novel theoretical/computational approach which, combining path-integral molecular dynamics (PIMD) simulations carried out with the MB-pol potential energy function and time-dependent density functional theory (TD-DFT) calculations, correctly predicts the split of the 1<i>b</i><sub>1</sub> peak in liquid water and not in crystalline ice. A systematic analysis in terms of the underlying local structure of liquid water at ambient conditions indicates that several different hydrogen-bonding motifs contribute to the overall XE lineshape in the energy range corresponding to emissions from the 1<i>b</i><sub>1</sub> orbitals, which suggests that it is not possible to unambiguously attribute the split of the 1<i>b</i><sub>1</sub> peak to only two specific structural arrangements of the underlying hydrogen-bonding network.

scholarly journals On the Relationship Between Hydrogen-Bonding Motifs and the 1b1 Splitting in the X-ray Emission Spectrum of Liquid Water

2020 ◽  
Author(s):  
Vinicius Cruzeiro ◽  
Andrew Wildman ◽  
Xiasong Li ◽  
Francesco Paesani
Keyword(s):  
Hydrogen Bonding ◽  
Liquid Water ◽  
Density Functional ◽  
Potential Energy Function ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Systematic Analysis ◽  
X Ray ◽  
Td Dft ◽  
The Relationship

The split of the 1<i>b</i><sub>1</sub> peak observed in the X-ray emission (XE) spectrum of liquid water has been the focus of intense research over the last two decades. Although several hypotheses have been proposed to explain the origin of the 1<i>b</i><sub>1</sub> splitting, a general consensus has not yet been reached. In this study, we introduce a novel theoretical/computational approach which, combining path-integral molecular dynamics (PIMD) simulations carried out with the MB-pol potential energy function and time-dependent density functional theory (TD-DFT) calculations, correctly predicts the split of the 1<i>b</i><sub>1</sub> peak in liquid water and not in crystalline ice. A systematic analysis in terms of the underlying local structure of liquid water at ambient conditions indicates that several different hydrogen-bonding motifs contribute to the overall XE lineshape in the energy range corresponding to emissions from the 1<i>b</i><sub>1</sub> orbitals, which suggests that it is not possible to unambiguously attribute the split of the 1<i>b</i><sub>1</sub> peak to only two specific structural arrangements of the underlying hydrogen-bonding network.

Synthesis, structure characterization, photoluminescence properties and TD–DFT calculations for two new borates

2018 ◽  
Vol 74 (4) ◽  
pp. 411-417 ◽  
Author(s):  
Nasreddine Hadjadj ◽  
Mohamed AbdEsselem Dems ◽  
Hocine Merazig ◽  
Lamia Bendjeddou
Keyword(s):  
Density Functional ◽  
Light Emission ◽  
Blue Emission ◽  
Structure Characterization ◽  
Photoluminescence Properties ◽  
Ambient Conditions ◽  
Functional Theory ◽  
Bidentate Coordination ◽  
Tetrahedral Environment ◽  
Td Dft

Due to their rich structural chemistry and wide variety of applications, borate materials have provided a rich area of research. In a continuation of this research, diethylammonium bis(2-oxidobenzoato-κ2 O 1,O 2)borate, C4H12N+·BO4(C7H4O)2 −, (1), and propylammonium bis(2-oxidobenzoato-κ2 O 1,O 2)borate, C3H10N+·BO4(C7H4O)2 −, (2), have been synthesized by the reaction of boric acid with salicylic acid under ambient conditions. In both structures, the B atom exhibits a slightly distorted tetrahedral environment formed by the bidentate coordination of two salicylate anions via the O atoms of the central carboxylate and oxide groups. In the crystals of salts (1) and (2), mixed cation–anion layers lying parallel to the (101) plane are formed through N—H...O, C—H...O and C—H...π/N—H...O hydrogen-bonding interactions, resulting, in each case, in a two-dimensional supramolecular architecture in the solid state. The photoluminescence properties of the salts were studied using the as-synthesized samples and reveal that salts (1) and (2) both display a strong blue-light emission, with maxima at 489 and 491 nm, respectively. In DFT/TD–DFT (time-dependent density functional theory) studies, the blue emission appears to be derived from an intramolecular charge transfer (ICT) excited state. In addition, IR and UV–Vis spectroscopies were used to investigate the title salts.

pH-related fluorescence quenching mechanism of pterin derivatives and the effects of 6-site substituents

2018 ◽  
Vol 96 (4) ◽  
pp. 404-410
Author(s):  
Lei Liu ◽  
Bingqing Sun
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonding ◽  
Fluorescence Quenching ◽  
Density Functional ◽  
Relaxation Processes ◽  
Quenching Mechanism ◽  
Functional Theory ◽  
Td Dft ◽  
Fluorescence Quenching Mechanism ◽  
Acidic Conditions

2-Amino-4-hydroxypteridine (pterin) and its derivatives serve as photooxidants and exhibit strong fluorescence. When they interact with hydrogen acceptors such as acetate and phosphate, their fluorescences are significantly quenched in acidic conditions (pH 4.9–5.5) but are retained in basic conditions (pH 10.0–10.5). This pH-related fluorescence quenching mechanism of pterin and its derivatives are fully investigated by using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). Pterin and its derivatives are demonstrated to show favorable excited-state proton transfer (ESPT) abilities in acidic conditions that induce the experimentally observed fluorescence quenching. In contrast, the ESPT processes are found to be retarded due to the lack of strong hydrogen-bonding interactions in basic environments, which sustain their fluorescence. Interestingly, these ESPT processes are found to show different site specificities depending on the 6-site substituents. The introduction of electron-donating substituent activates the N1 site, making it the preferred ESPT site. By contrast, the introduction of an electron-withdrawing substituent activates the N5 site, making it the favorable ESPT site. The substitutions of different functional groups are found to affect the locations of acidic centers during the excitation and relaxation processes. This further affects the hydrogen-bonding patterns and ultimately brings site specificity to the ESPT process.

scholarly journals A multinuclear solid state NMR, density functional theory and X-Ray diffraction study of hydrogen bonding in Group I hydrogen dibenzoates

CrystEngComm ◽  
2013 ◽  
Vol 15 (43) ◽  
pp. 8823 ◽  
Author(s):  
Gregory J. Rees ◽  
Stephen P. Day ◽  
Alberth Lari ◽  
Andrew P. Howes ◽  
Dinu Iuga ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bonding ◽  
Solid State ◽  
Diffraction Study ◽  
Solid State Nmr ◽  
Density Functional ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Group I

scholarly journals Fluorine-Containing Dibenzoanthracene and Benzoperylene-Type Polycyclic Aromatic Hydrocarbons: Synthesis, Structure, and Basic Chemical Properties

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3337 ◽  
Author(s):  
Otohiro Gotsu ◽  
Tomomi Shiota ◽  
Hiroki Fukumoto ◽  
Tomoko Kawasaki-Takasuka ◽  
Takashi Yamazaki ◽  
...  
Keyword(s):  
Density Functional ◽  
Dft Calculation ◽  
Chemical Properties ◽  
Crystallographic Analysis ◽  
Functional Theory ◽  
X Ray ◽  
Td Dft ◽  
Polycyclic Aromatic ◽  
Stilbene Derivatives ◽  
Hydrocarbons Synthesis

Intramolecular photocyclization of stilbene derivatives (Mallory reaction) is one of the efficient methods for building polycyclic aromatic hydrocarbon (PAH) frameworks, and is also expected to be applicable to synthesis of fluorine-containing PAHs (F-PAHs). In this study, dibenzoanthracene-type (4a) and benzoperylene-type (4b) F-PAHs were synthesized using the Mallory reaction of the 1,4-distyrylbenzene-type π-conjugated molecule (3a), which was prepared by addition-defluorination of available octafluorocyclopentene (OFCP) and aryllithium in three steps. The structure of 4a originating from π–π interaction was characterized by X-ray crystallographic analysis. The absorption maxima of UV-Vis spectra and emission maxima of photoluminescence spectra of the PAHs were positioned at a longer wavelength compared to those of the corresponding unsubstituted PAHs, presumably due to the electron-withdrawing nature of perfluorocyclopentene (PFCP) units. The effect of PFCP units in F-PAHs was also studied by time-dependent density functional theory (TD-DFT) calculation.

scholarly journals Boosting the Stability of Boron Peroxides through Subphthalocyanine Coordination

2021 ◽  
Vol 03 (02) ◽  
pp. 141-145
Author(s):  
Jorge Labella ◽  
Elisa López-Serrano ◽  
Tomás Torres
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Lewis Base ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
The Stability ◽  
The Impact ◽  
Structural And Optoelectronic Properties

The great potential of subphthalocyanines (SubPcs) to stabilize boron peroxides has been demonstrated. In particular, a subphthalocyanato boron (III) peroxide has been prepared in good yield via boron triflate. This derivative is remarkably stable under ambient conditions and can be fully characterized. The impact of the peroxide group on the structural and optoelectronic properties of SubPc was examined by NMR and UV/Vis spectroscopies, as well as single-crystal X-ray diffraction analysis. Moreover, density functional theory calculations were performed to explain the experimental results. The reactivity of this peculiar boron peroxide as an oxidant and a Lewis base was also studied.

scholarly journals Requirements of first-principles calculations of X-ray absorption spectra of liquid water

2016 ◽  
Vol 18 (1) ◽  
pp. 566-583 ◽  
Author(s):  
Thomas Fransson ◽  
Iurii Zhovtobriukh ◽  
Sonia Coriani ◽  
Kjartan T. Wikfeldt ◽  
Patrick Norman ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Liquid Water ◽  
First Principles ◽  
Density Functional ◽  
Time Dependent ◽  
First Principles Calculations ◽  
Functional Theory ◽  
X Ray ◽  
X Ray Absorption ◽  
Dependent Density

Transition-potential and time-dependent density functional theory XAS calculations are presented for water and ice, showing excellent agreement between TDDFT results and experimental spectra.

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