Synthesis, Raman, X-ray diffraction, and density functional studies of antimony(III) heterotetracycles displaying intramolecular transannular interactions O → Sb

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

Download Full-text

On tungstates of divalent cations (III) – Pb5O2[WO6]

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2020-0041 ◽

2020 ◽

Vol 235 (8-9) ◽

pp. 311-317

Author(s):

Stephan G. Jantz ◽

Florian Pielnhofer ◽

Henning A. Höppe

Keyword(s):

Crystal Structure ◽

Thermal Analysis ◽

Quantum Chemical ◽

Density Functional ◽

Divalent Cations ◽

X Ray Diffraction ◽

Functional Theory ◽

X Ray ◽

First Results ◽

Electrostatic Calculations

Abstract${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ was discovered as a frequently observed side phase during our investigation on lead tungstates. Its crystal structure was solved by single-crystal X-ray diffraction ($P{2}_{1}/n$, $a=7.4379\left(2\right)$ Å, $b=12.1115\left(4\right)$ Å, $c=10.6171\left(3\right)$ Å, $\beta =90.6847\left(8\right)$°, $Z=4$, ${R}_{\text{int}}=0.038$, ${R}_{1}=0.020$, $\omega {R}_{2}=0.029$, 4188 data, 128 param.) and is isotypic with ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{Te}}_{6}\right]$. ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ comprises a layered structure built up by non-condensed [WO6]${}^{6-}$ octahedra and ${\left[{\text{O}}_{4}{\text{Pb}}_{10}\right]}^{12+}$ oligomers. The compound was characterised by spectroscopic measurements (Infrared (IR), Raman and Ultraviolet–visible (UV/Vis) spectra) as well as quantum chemical and electrostatic calculations (density functional theory (DFT), MAPLE) yielding a band gap of 2.9 eV fitting well with the optical one of 2.8 eV. An estimation of the refractive index based on the Gladstone-Dale relationship yielded $n\approx 2.31$. Furthermore first results of the thermal analysis are presented.

Download Full-text

In situ x-ray photoelectron spectroscopic and density-functional studies of Si atoms adsorbed on a C[sub 60] film

The Journal of Chemical Physics ◽

10.1063/1.1814053 ◽

2004 ◽

Vol 121 (22) ◽

pp. 11351 ◽

Cited By ~ 3

Author(s):

Jun Onoe ◽

Aiko Nakao ◽

Toshiki Hara

Keyword(s):

Density Functional ◽

X Ray ◽

Functional Studies

Download Full-text

Si Nanoribbons on Ag(110) Studied by Grazing-Incidence X-Ray Diffraction, Scanning Tunneling Microscopy, and Density-Functional Theory: Evidence of a Pentamer Chain Structure

Physical Review Letters ◽

10.1103/physrevlett.117.276102 ◽

2016 ◽

Vol 117 (27) ◽

Cited By ~ 17

Author(s):

Geoffroy Prévot ◽

Conor Hogan ◽

Thomas Leoni ◽

Romain Bernard ◽

Eric Moyen ◽

...

Keyword(s):

Density Functional Theory ◽

Scanning Tunneling Microscopy ◽

Density Functional ◽

Grazing Incidence ◽

Chain Structure ◽

Scanning Tunneling ◽

X Ray Diffraction ◽

Tunneling Microscopy ◽

Functional Theory ◽

X Ray

Download Full-text

Metal-Rich Metallaboranes: Synthesis, Structures and Bonding of Bi- and Trimetallic Open-Faced Cobaltaboranes

Inorganics ◽

10.3390/inorganics9040028 ◽

2021 ◽

Vol 9 (4) ◽

pp. 28

Author(s):

Kriti Pathak ◽

Chandan Nandi ◽

Jean-François Halet ◽

Sundargopal Ghosh

Keyword(s):

Electronic Structures ◽

Density Functional ◽

Room Temperature ◽

Electron Pair ◽

X Ray Diffraction ◽

Functional Theory ◽

X Ray ◽

Cluster 2 ◽

Cobalt Center

Synthesis, isolation, and structural characterization of unique metal rich diamagnetic cobaltaborane clusters are reported. They were obtained from reactions of monoborane as well as modified borohydride reagents with cobalt sources. For example, the reaction of [Cp*CoCl]2 with [LiBH4·THF] and subsequent photolysis with excess [BH3·THF] (THF = tetrahydrofuran) at room temperature afforded the 11-vertex tricobaltaborane nido-[(Cp*Co)3B8H10] (1, Cp* = η5-C5Me5). The reaction of Li[BH2S3] with the dicobaltaoctaborane(12) [(Cp*Co)2B6H10] yielded the 10-vertex nido-2,4-[(Cp*Co)2B8H12] cluster (2), extending the library of dicobaltadecaborane(14) analogues. Although cluster 1 adopts a classical 11-vertex-nido-geometry with one cobalt center and four boron atoms forming the open pentagonal face, it disobeys the Polyhedral Skeletal Electron Pair Theory (PSEPT). Compound 2 adopts a perfectly symmetrical 10-vertex-nido framework with a plane of symmetry bisecting the basal boron plane resulting in two {CoB3} units bridged at the base by two boron atoms and possesses the expected electron count. Both compounds were characterized in solution by multinuclear NMR and IR spectroscopies and by mass spectrometry. Single-crystal X-ray diffraction analyses confirmed the structures of the compounds. Additionally, density functional theory (DFT) calculations were performed in order to study and interpret the nature of bonding and electronic structures of these complexes.

Download Full-text

Investigation of Solvatomorphism and Its Photophysical Implications for Archetypal Trinuclear Au3(1-Methylimidazolate)3

Molecules ◽

10.3390/molecules26154404 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4404

Author(s):

Shengyang Guan ◽

David C. Mayer ◽

Christian Jandl ◽

Sebastian J. Weishäupl ◽

Angela Casini ◽

...

Keyword(s):

Crystal Structure ◽

Solid State ◽

Density Functional ◽

Bulk Material ◽

Variable Temperature ◽

Active Phase ◽

Solvent Free ◽

X Ray Diffraction ◽

X Ray ◽

Aurophilic Interactions

A new solvatomorph of [Au3(1-Methylimidazolate)3] (Au3(MeIm)3)—the simplest congener of imidazolate-based Au(I) cyclic trinuclear complexes (CTCs)—has been identified and structurally characterized. Single-crystal X-ray diffraction revealed a dichloromethane solvate exhibiting remarkably short intermolecular Au⋯Au distances (3.2190(7) Å). This goes along with a dimer formation in the solid state, which is not observed in a previously reported solvent-free crystal structure. Hirshfeld analysis, in combination with density functional theory (DFT) calculations, indicates that the dimerization is generally driven by attractive aurophilic interactions, which are commonly associated with the luminescence properties of CTCs. Since Au3(MeIm)3 has previously been reported to be emissive in the solid-state, we conducted a thorough photophysical study combined with phase analysis by means of powder X-ray diffraction (PXRD), to correctly attribute the photophysically active phase of the bulk material. Interestingly, all investigated powder samples accessed via different preparation methods can be assigned to the pristine solvent-free crystal structure, showing no aurophilic interactions. Finally, the observed strong thermochromism of the solid-state material was investigated by means of variable-temperature PXRD, ruling out a significant phase transition being responsible for the drastic change of the emission properties (hypsochromic shift from 710 nm to 510 nm) when lowering the temperature down to 77 K.

Download Full-text

Thermal-induced transformation of glutamic acid to pyroglutamic acid and self-cocrystallization: a charge–density analysis

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229621013607 ◽

2022 ◽

Vol 78 (2) ◽

Author(s):

Sehrish Akram ◽

Arshad Mehmood ◽

Sajida Noureen ◽

Maqsood Ahmed

Keyword(s):

Hydrogen Bonds ◽

Glutamic Acid ◽

Single Crystal ◽

Diffraction Data ◽

Density Functional ◽

Quantitative Estimation ◽

Topological Analysis ◽

Pyroglutamic Acid ◽

X Ray Diffraction ◽

X Ray

Thermal-induced transformation of glutamic acid to pyroglutamic acid is well known. However, confusion remains over the exact temperature at which this happens. Moreover, no diffraction data are available to support the transition. In this article, we make a systematic investigation involving thermal analysis, hot-stage microscopy and single-crystal X-ray diffraction to study a one-pot thermal transition of glutamic acid to pyroglutamic acid and subsequent self-cocrystallization between the product (hydrated pyroglutamic acid) and the unreacted precursor (glutamic acid). The melt upon cooling gave a robust cocrystal, namely, glutamic acid–pyroglutamic acid–water (1/1/1), C5H7NO3·C5H9NO4·H2O, whose structure has been elucidated from single-crystal X-ray diffraction data collected at room temperature. A three-dimensional network of strong hydrogen bonds has been found. A Hirshfeld surface analysis was carried out to make a quantitative estimation of the intermolecular interactions. In order to gain insight into the strength and stability of the cocrystal, the transferability principle was utilized to make a topological analysis and to study the electron-density-derived properties. The transferred model has been found to be superior to the classical independent atom model (IAM). The experimental results have been compared with results from a multipolar refinement carried out using theoretical structure factors generated from density functional theory (DFT) calculations. Very strong classical hydrogen bonds drive the cocrystallization and lend stability to the resulting cocrystal. Important conclusions have been drawn about this transition.

Download Full-text

Structure and Electrochemical Potential Simulation for the Cathode Material Li1+xV3O8

MRS Proceedings ◽

10.1557/proc-496-115 ◽

1997 ◽

Vol 496 ◽

Cited By ~ 1

Author(s):

R. Benedek ◽

M. M. Thackeray ◽

L. H. Yang

Keyword(s):

Density Functional ◽

Structural Information ◽

Local Density ◽

Tetrahedral Site ◽

Low Energy ◽

Electrochemical Potential ◽

X Ray Diffraction ◽

X Ray ◽

Local Density Functional Theory ◽

Two Phases

ABSTRACTThe structure and electrochemical potential of monoclinic Li1+xV3O8 were calculated within the local-density-functional-theory framework by use of plane-wave-pseudopotential methods. Special attention was given to the compositions 1+x=1.2 and 1+x=4, for which x-ray diffraction structure refinements are available. The calculated low-energy configuration for 1+x=4 is consistent with the three Li sites identified in x-ray diffraction measurements and predicts the position of the unobserved Li. The location of the tetrahedrally coordinated Li in the calculated low-energy configuration for 1+x=1.5 is consistent with the structure measured by x-ray diffraction for Li1.2V3O8. Calculations were also performed for the two monoclinic phases at intermediate Li compositions, for which no structural information is available. Calculations at these compositions are based on hypothetical Li configurations suggested by the ordering of vacancy energies for Li4V3O8 and tetrahedral site energies in Li1.5V3O8. The internal energy curves for the two phases- cross near 1+x=3. Predicted electrochemical potential curves agree well with experiment.

Download Full-text