18 research outputs found
Exploring disorder correlations in superconducting systems: spectroscopic insights and matrix element effects
Understanding the intricate interplay between disorder and superconductivity has become a key area of research in condensed matter physics, with profound implications for materials science. Recent studies have shown that spatial correlations of disorder potential can improve superconductivity, prompting a re-evaluation of some theoretical models. This paper explores the influence of disorder correlations on the fundamental properties of superconducting systems, going beyond the traditional assumption of spatially uncorrelated disorder. In particular, we investigate the influence of disorder correlations on key spectroscopic superconductor properties, including the density of states, as well as on the matrix elements of the superconducting coupling constant and their impact on the localization length. Our findings offer valuable insights into the role of disorder correlations in shaping the behavior of superconducting materials
Genetic and Phylogenetic Characterization of Tataguine and Witwatersrand Viruses and Other Orthobunyaviruses of the Anopheles A, Capim, Guamá, Koongol, Mapputta, Tete, and Turlock Serogroups
The family Bunyaviridae has more than 530 members that are distributed among five genera or remain to be classified. The genus Orthobunyavirus is the most diverse bunyaviral genus with more than 220 viruses that have been assigned to more than 18 serogroups based on serological cross-reactions and limited molecular-biological characterization. Sequence information for all three orthobunyaviral genome segments is only available for viruses belonging to the Bunyamwera, Bwamba/Pongola, California encephalitis, Gamboa, Group C, Mapputta, Nyando, and Simbu serogroups. Here we present coding-complete sequences for all three genome segments of 15 orthobunyaviruses belonging to the Anopheles A, Capim, Guamá, Kongool, Tete, and Turlock serogroups, and of two unclassified bunyaviruses previously not known to be orthobunyaviruses (Tataguine and Witwatersrand viruses). Using those sequence data, we established the most comprehensive phylogeny of the Orthobunyavirus genus to date, now covering 15 serogroups. Our results emphasize the high genetic diversity of orthobunyaviruses and reveal that the presence of the small nonstructural protein (NSs)-encoding open reading frame is not as common in orthobunyavirus genomes as previously thought
Photochemical Rearrangement of Diarylethenes: Reaction Efficiency and Substituent Effects
In
recent years, great synthetic potential of the photorearrangement
of diarylethenes leading to naphthalene derivatives via a cascade
process of photocyclization/[1,<i>n</i>]-H shift/cycloreversion
has been demonstrated. In this work, first a multifaceted study of
the influence of various factors on the efficiency of the photorearrangement
of diarylethenes of furanone series containing benzene and oxazole
derivatives as aryl residues has been carried out. The efficiency
of this phototransformation (quantum yields) and the effect of methoxy
substituents in the phenyl moiety have been studied. Despite the multistage
process, the quantum yields of the photorearrangement are rather high
(0.34–0.49). It has been found that the efficiency of photocyclization
of diarylethenes increases with the introduction of electron-donating
methoxy groups in the phenyl moiety. Using the DFT calculations, we
have been able to estimate in the photoinduced isomer the distance
between hydrogen atom and carbon atom to which it migrates in the
result of the sigmatropic shift. For all studied diarylethenes, this
value was 2.67–2.73 Å, which is less than the sum of van
der Waals radii of carbon and hydrogen atoms (2.9 Ă…)
Aerobic Dimerization of Ethyl 4‑Thienyl-3-ketobutanoate toward a Modifiable Photochromic Diarylethene Precursor
A unique chemical
transformation, the base-induced aerobic dimerization
of ethyl 4-(2,5-dimethylthiophen-3-yl)-3-ketobutanoate leading to
photochromic diarylethene with a 4-hydroxy-4-methylcyclopent-2-ene-1-one
as an ethene bridge, is described. This compound is easily subjected
to various chemical modifications and can be used as a new diarylethene
precursor to produce photoactive compounds with desired properties
and functions
Synthesis and Comparative Photoswitching Studies of Unsymmetrical 2,3-Diarylcyclopent-2-en-1-ones
Photochromic diarylethenes (DAEs)
based on the unsymmetrical ethene
“bridge” bearing heterocycles of the different nature
(oxazole and thiophene) as aromatic moieties have been designed and
the photoswitching properties have been studied. The comparative studies
of the photochromic characteristics of unsymmetrical isomeric 2,3-diarylcyclopent-2-en-1-ones
have shown that the isomers have different thermal stability, absorption
maxima, and quantum yields. It was found that the unsymmetrical diarylÂcycloÂpentenone
bearing at second position of the cyclopentenone ring the thiophene
unit displays high thermally stability, hypsochromic shift of absorption
maxima wavelengths of initial and cyclic forms, and high quantum yields
of cyclization and cycloreversion reactions. The replacement of the
carbonyl group with oxime leads to a reduction of the difference in
the photochromic properties of these isomers and just as the reduction
of the carbonyl group to the hydroxy-group negates this difference
to zero. The intramolecular hydrogen bond formation in the oxime and
hydroxy derivatives was confirmed by IR and <sup>1</sup>H NMR spectral
analysis, but the increase of the quantum yields of the cyclization
reaction in a nonpolar hexane is observed only in the case of hydroxy
derivatives that can be explained by the formation of more rigid six-membered
heterocycle in hydrogen bonding
Density of states in the presence of spin-dependent scattering in SF bilayers: a numerical and analytical approach
We present a quantitative study of the density of states (DOS) in SF bilayers (where S is a bulk superconductor and F is a ferromagnetic metal) in the diffusive limit. We solve the quasiclassical Usadel equations in the structure considering the presence of magnetic and spin–orbit scattering. For practical reasons, we propose the analytical solution for the density of states in SF bilayers in the case of a thin ferromagnet and low transparency of the SF interface. This solution is confirmed by numerical calculations using a self-consistent two-step iterative method. The behavior of DOS dependencies on magnetic and spin–orbit scattering times is discussed
Photoinduced Skeletal Rearrangement of Diarylethenes Comprising Oxazole and Phenyl Rings
A novel
photochemical rearrangement of diarylethenes bearing oxazole
and benzene derivatives as aryl moieties that results in the formation
of polyaromatic systems was investigated. The mechanism of the transformation
includes photocyclization, sequential [1,9] and [1,3]-hydrogen shifts,
as well as a lateral oxazole ring-opening process. It was shown that
this reaction can be an effective synthetically preparative method
for the preparation of naphthalene (polyaromatic) derivatives
Triaryl-Substituted Divinyl Ketones Cyclization: Nazarov Reaction versus Friedel–Crafts Electrophilic Substitution
The acid-catalyzed cyclization
of a wide range of triaryl-substituted divinyl ketones has been studied.
It was found that the reaction pathway strongly depends on the nature
of the aryl substituent at the α-position to the carbonyl group.
An electron-rich aromatic substituent promotes the reaction to proceed
through the intramolecular Friedel–Crafts electrophilic substitution
giving dihydroÂnaphthalene derivatives. In contrast, the presence
of an electron-deficient substituent is favorable for the Nazarov
4Ď€-conrotatory cyclization yielding triaryl-substituted cyclopentenones.
The electrophilic substitution reaction was applied to thiophene and
thiazole derivatives
Structural and Spectral Properties of Photochromic Diarylethenes: Size Effect of the Ethene Bridge
The
effect of the size of the ethene bridge on the structural and
spectral properties of photochromic diarylethenes, which remains a
poorly understood phenomenon, was studied as applied to diarylethenes
containing unsymmetrical (cyclohexenone and cyclopentenone) and symmetrical
(cyclohexene and cyclopentene) ethene bridges. Thiophene, oxazole,
and imidazole derivatives were used as aryl moieties. An increase
in the size of the ethene bridge in the cycloalkenone series was found
to be accompanied by a hypsochromic shift of the absorption maximum
of the photoinduced form, whereas no difference was found for cycloalkenes.
A detailed analysis of the NMR spectra (including 2D experiments)
revealed previously unknown effects associated with the existence
of an intramolecular hydrogen bond (CH···N) between
the six-membered ethene bridge and the azole substituents. The NMR
experimental data obtained were confirmed by DFT quantum chemical
calculations and X-ray analysis. It was found that an intramolecular
hydrogen bond favors an increase of the quantum yield of the photocyclization
reaction
General Photoinduced Sequential Electrocyclization/[1,9]-Sigmatropic Rearrangement/Ring-Opening Reaction of Diarylethenes
A novel
and efficient photochemical transformation of diarylethenes
comprising a five-membered heterocyclic ring and phenyl moiety is
described. This reaction provides a simple method for the preparation
of functionalized naphthalene derivatives via photorearrangement reaction
of diarylethenes, and the process is characterized by high efficiency
that was determined by NMR monitoring. Some mechanistic aspects of
this process have been also explored. It was found that the reaction
includes tandem transformation of three basic processes: the photocyclization
of the hexatriene system, [1,9]-sigmatropic rearrangement, and heterocyclic
ring opening. Diarylethenes with different heterocycle moieties (thiophene,
benzoÂ[<i>b</i>]Âthiophene, furan, indole, imidazole, thiazole,
oxazole, pyrazole) have been involved into this process, and the target
naphthalenes with good yields have been obtained. The opportunity
for use in the transformation of diarylethenes with different heterocyclic
residues permits synthesis of naphthalenes with desired functional
groups. The general character and high efficiency of the reaction
promise that the transformation can be an effective synthetic route
for the annulation of benzene rings to various aromatic systems, including
heterocycles