113 research outputs found
Aromatic C–H⋯π, C–H⋯O and parallel aromatic–aromatic interactions in the crystal structure of meso-tetrakis[4-(benzyloxy)phenyl] porphyrin
Analysis of the crystal packing of the title porphyrin derivative (
C72H54N4O4) suggests no classical hydrogen bonds between
neighbor molecules. X-ray crystal structure shows that all benzyl units of this porphyrin have close C–H⋯π weak contacts
with phenyl or porphyrinyl units forming a network of porphyrin rings. Also C–H⋯O and parallel aromatic–aromatic weak
interactions play an important role in structure extension. All of these interactions control the crystal packing of molecules.
X-ray diffraction was used to perform single crystal analysis. The structure was solved in the triclinic space group P-1, with
unit cell parameters: a = 8.0597(3) Å, b = 11.6862(4) Å, c = 14.2572(5) Å, α = 96.173(3)°, β = 93.150(4)°, and γ = 93.679(3)°,
V = 1329.72(8) Ã…3, Z = 1
Fidelity susceptibility in Gaussian Random Ensembles
The fidelity susceptibility measures sensitivity of eigenstates to a change
of an external parameter. It has been fruitfully used to pin down quantum phase
transitions when applied to ground states (with extensions to thermal states).
Here we propose to use the fidelity susceptibility as a useful dimensionless
measure for complex quantum systems. We find analytically the fidelity
susceptibility distributions for Gaussian orthogonal and unitary universality
classes for arbitrary system size. The results are verified by a comparison
with numerical data.Comment: 2nd version, 5+5pp, comments welcom
2,3-O-Isopropylidene-1-O-p-tolylsulfonylglycerol
In the title compound, C13H18O5S, the five-membered ring has
an envelope conformation. The packing involves four C—
H O interactions, three of which combine to form layers of
molecules parallel to the bc plane
Spectroscopic and crystallographic characterization of two cathinone derivatives : 1-(4-fluorophenyl)-2-(methylamino)pentan-1-one (4-FPD) hydrochloride and 1-(4-methylphenyl)-2-(ethylamino)pentan-1-one (4-MEAP) hydrochloride
Purpose In this study, we performed identification and physicochemical characterization of two cathinone derivatives, 4-FPD
and 4-MEAP, found in market-available materials.
Methods The compounds were characterized by electrospray ionization ion trap mass spectrometry (MS) in MS2
and MS3
modes, gas chromatography–MS, infrared, Raman and ultraviolet-visible spectroscopies, X-ray crystallography, differential
scanning calorimetry and nuclear magnetic resonance spectroscopy.
Results We could obtain detailed and comprehensive physicochemical characterization of 4-FPD and 4-MEAP—new cathinone
derivatives available on the designer drugs market.
Conclusions Dynamic growth in the number of psychoactive substances available on the designer drug markets makes it
compulsory to obtain analytical data allowing unequivocal identification of these drugs in the fastest possible way. In this
study we presented analytical data useful in quick identification of the investigated compounds
On determination of statistical properties of spectra from parametric level dynamics
We analyze an approach aiming at determining statistical properties of
spectra of time-periodic quantum chaotic system based on the parameter dynamics
of their quasienergies. In particular we show that application of the methods
of statistical physics, proposed previously in the literature, taking into
account appropriate integrals of motion of the parametric dynamics is fully
justified, even if the used integrals of motion do not determine the invariant
manifold in a unique way. The indetermination of the manifold is removed by
applying Dirac's theory of constrained Hamiltonian systems and imposing
appropriate primary, first-class constraints and a gauge transformation
generated by them in the standard way. The obtained results close the gap in
the whole reasoning aiming at understanding statistical properties of spectra
in terms of parametric dynamics.Comment: 9 pages without figure
(2,2-Dimethyl-1,3-dioxolan-4-yl)methyl 3-carboxyÂpropanoate
In the title compound, C10H16O6, the five-membered ring has an envelope conformation. The packing involves hydrogen-bonded carboxylic acid inversion dimers and three C—H⋯O interÂactions
Dimorphism of 1,4-dibromo-2,5-bis(bromomethyl)benzene: crystallographic and physico-chemical investigations
Two polymorphic modifications of 1,4-dibromo-2,5-bisIJbromomethyl)benzene have been discovered and
structurally characterized; their thermodynamic relationships and transformation behaviour have been investigated. Form I crystallizes in the triclinic space group P1¯, whereas form II crystallizes monoclinic in
space group P21/c, both with imposed inversion symmetry of the molecule. Their crystal structures involve
layers, in which the molecules are linked by intermolecular Br⋯Br interactions to form similar systems of
linked rings. Initial studies involved batches consisting of pure form I or a mixture of I with traces of II (as
obtained by chance from the synthesis), but solvent-mediated conversion experiments in various solvents
clearly prove that form II is the thermodynamically stable form at room temperature. Thermomicroscopic
and heating-rate-dependent DSC measurements show that the melting point of form I is slightly higher
than that of form II and that the higher melting polymorph exhibits the lower heat of fusion. Therefore,
form I becomes thermodynamically stable at higher temperatures and both forms are related by enantiotropism.
This is also in agreement with the density rule, because the low-temperature form II exhibits the
higher density. Isothermal annealing of both modifications at different temperatures reveals a thermodynamic
transition temperature of about 135 °C, which is in excellent agreement with that of 137.5 °C calculated
from the melting temperatures and the heat of fusion of both forms. The high-temperature form can
easily be prepared pure by solidification of the melt, which is in agreement with Ostwald's step rule, because
form I crystallizes at a temperature where it is thermodynamically metastable. A qualitative energy/
temperature diagram is presented
Identification and characterization of new designer drug 4-fluoro-PV9 and [alfa]-PHP in the seized materials
In this study, we present identification and
physicochemical characterization of new cathinone
derivatives, 4-fluoro-PV9 and already known a-PHP in
seized materials. Although the disclosure of a-PHP from an
illegal product had been reported and characterized to some
extent, the data on a-PHP are also presented together with
those of 4-fluoro-PV9. The data of characterization for the
two compounds were obtained by high-performance liquid
chromatography (HPLC)–mass spectrometry and HPLC–
diode array detection, electrospray ionization/ion trap mass
spectrometry in MS2 and MS3 modes, gas chromatography–
mass spectrometry, thermogravimetric analysis, differential
scanning calorimetry, Fourier transform infrared
spectroscopy, ultraviolet-visible spectroscopy, and nuclear
magnetic resonance spectroscopy. To our knowledge, this
is the first report for identification and detailed characterization
of 4-fluoro-PV9 circulated on the illegal drug
market
Spectroscopic characterization and crystal structures of two cathinone derivatives : N-ethyl-2-amino-1-phenylpropan-1-one (ethcathinone) hydrochloride and N-ethyl-2-amino-1-(4-chlorophenyl)propan-1-one (4-CEC) hydrochloride
Comprehensive chemical characterization for two cathinone derivatives, N-ethyl-2-amino-1-phenylpropan-1-one (ethcathinone) hydrochloride and N-ethyl-2-amino-1-(4-chlorophenyl)-propan-1-one (4-chloroethcathinone, 4-CEC) hydrochloride, in material seized by drug enforcement agencies was performed by nuclear magnetic resonance (NMR) spectroscopy, infrared spectroscopy, gas chromatography–mass spectrometry in positive electron ionization mode, liquid chromatography–mass spectrometry in positive electrospray ionization mode and X-ray crystallography. The examined samples of these two compounds proved to be very pure for ethcathinone and mixed with very small quantities of other substances for 4-CEC by NMR spectroscopy and mass spectrometry. X-ray crystallographic studies confirmed the occurrence of both compounds as racemic mixtures. These spectroscopic and crystallographic data seem very useful for their identification. Especially for 4-CEC, this is the first description on its spectroscopic characterization in a scientific context to our knowledge
Crystal structure of sparteinium tetrachlorocuprate monohydrate‑packing polymorph
A new polymorph of sparteinium tetrachlorocuprate monohydrate [(C15H28N2)CuCl4·H2O] is reported. The structure of
the analyzed crystal was solved in the orthorhombic P212121 space group with the following unit cell parameters at 295 K:
a = 9.7722(2) Ã…; b = 13.4582(3) Ã…; c = 15.1582(3) Ã…. The various types of hydrogen bonding interactions existing in the
crystal structure of this salt were compared with the data of the previously reported polymorph. XRPD measurement proved
that our salt consists of a pure phase of the new polymorph. Cooling down the salt to ca. 230 K caused its color to change
from orange-brown to yellow. DSC experiments revealed that during the cooling an endothermic process takes place corresponding
to the mentioned color change of the salt
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