bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetische Untersuchungen an Komplexen des Vanadyls mit mehrzähnigen Liganden
Authors: Hoffmann H. , Ulbricht W. 
Published: November 2023

AbstractMit Hilfe einer Drucksprungapparatur wurde die Kinetik der Komplexbildung des Vanadyl‐Kations mit den Chelat‐bildenden Liganden Malonat, Oxalat, L‐Tartrat und racemischem Tartrat untersucht. Dabei wurden an den Systemen VO‐Malonsäure und VO‐Weinsäure jeweils drei Relaxationszeiten gefunden, die beim Malonat der Bildung der Komplexe (VOOH)2‐Mal, VOMal und VOMal2‐2, beim Oxalat der Bildung der Komplexe VOOx sowie der beiden strukturisomeren Komplexe VOOx2äq2−, und VOOx2ax2− zugeordnet wurden. Die gefundenen Geschwindigkeitskonstanten wurden diskutiert. Am System VO‐Weinsäure wurden zwei Relaxationszeiten gefunden, die analog dem Nickeltartrat [14] der Bildung der Komplexe VO ‐ T bzw. VOTH+ und (VO ‐ T)2 zugeordnet wurden. Auch hier wurde gefunden, daβ die Bildung des Doppelkomplexes stereospezifisch in der Weise erfolgt [15], daβ aus je einem VO ‐L‐T und einem VO ‐D‐T kein gemischter Doppelkomplex gebildet wird. Diese Analogie macht eine allgemeine Gültigkeit des Mechanismus der Komplexbildung mit Tartraten wahrscheinlich.
Complex formation of Co(II) with halides in aqueous solution
Authors: Krauß Ulrich , Lehmann Gerhard 
Published: November 2023

AbstractDie spektrophotometrische Untersuchung des Komplexgleichgewichts zwischen Co(H2O)62+und Halogeniden zeigte die Anwesenheit von CoX42−und der Innersphärkomplexe Co(H2O)5X+und Co(H2O)4X2ais Zwischenstufen. Die Konzentrationen anderer Zwischenstufen müssen unter 1% für tetraedrische und unter 5% für hexakoordinierte Komplexe liegen. Das Konzentrationsverhältnis zwischen CoX42−und den oktaedrischen Komplexen ändert sich mit der zehnten bis fünfzehnten Potenz der Halogenidkonzentration bei Zugabe von Lithium‐halogeniden oder Halogenwasserstoffen. Die Methode der konstanten Ionenstärke liefert ebenfalls zu hohe Werte für die Zahl der Halogenidionen im tetraedrischen Komplex.
Spektren und Grenzorbitale von Ti(IV)‐di‐cyclopentadienyl‐Komplexen
Authors: Habitz P. , Schwarz W. H. E. 
Published: November 2023

AbstractAuf der Basis von EHT(SCC)‐Rechnungen and qualitativen Symmetrieüberiegungen wird versucht, die elektronischen Spektren von Titan‐(IV)‐Sandwich‐Komplexen zu interpretieren. Es konnte gezeigt werden, daß die ersten schwachen Peaks im Gegensatz zu früheren Vermutungen orbitalerlaubten Anregungen entsprechen. Veränderungen im langwelligen Teil der Spektren bei Veränderung der Liganden sind qualitativ verständlich. Die wesentliche Lokalisierung der höchsten besetzten und tiefsten unbesetzten MO's stützt den von Olivé [1] vorgeschlagenen Übergangszustand der Ziegler‐Katalyse.
Some Aspects of the Anodic Behaviour of CdS Single Crystals in Indifferent Electrolyte Solutions
Authors: vanden Berghe R. A. L. , Gomes W. P. , Cardon F. 
Published: November 2023

AbstractThe anodic behaviour of CdS in contact with an indifferent electrolyte was studied in darkness and under illumination by current‐voltage, capacity‐voltage and analytical measurements. Marked effects of surface pretreatment on the current and the capacity were observed. The results suggest that pre‐breakdown phenomena are involved in the dark current mechanism as well as in some anomalies observed in the photocurrent under band‐gap illumination. Photo‐effects were also found at wavelengths up to 800 nm and ascribed to the presence of localised electron levels in the space charge region. Surface and sub‐surface imperfections appear to play an important role in the electrochemical behaviour of the CdS anode.
Bestimmung der Geschwindigkeitskonstanten einiger schwacher Säuren mit Hilfe rotierender Elektroden — Einfluß des elektrischen Feldes in der Doppelschicht
Authors: Gostiša‐Mihelčić B. , Vielstich W. 
Published: November 2023

AbstractDie Bestimmung der Geschwindigkeitskonstanten der Dissoziation und Rekombination schwacher Säuren HA ist auf elektrochemischem Wege nur dann möglich, wenn die Dissoziation der kathodischen Wasserstoffabscheidung im Grenzstrombereich vorgelagert ist:magnified imageUm den Antransport der HA‐Moleküle ausreichend zu beschleunigen, haben wir unsere Messungen an rotierenden Elektroden (Scheibe bzw. Ring) durchgeführt. Für die Sauren HCOOH, CH3COOH, CH3CH2COOH wurden neben den Geschwindigkeitskonstanten auch die Diffusionskoeffizienten bestimmt.Unter elektrochemischen Bedingungen findet der Reaktionsablauf in Lösungen mit Fremdelektrolyt (hier Ionenstärke I = 1) statt. Darüber hinaus ist eine Erhöhung des Dissoziationsgrades im starken elektrischen Feld der elektrolytischen Doppelschicht zu beachten. Um einen Anschluß an die Ergebnisse nichtelektrochemischer Messungen zu erhalten, haben wir daher den Einfluß des elektrischen Feldes auf die Dissoziationsgeschwindigkeit im Falle der Essigsäure durch Variation der Reaktionsschichtdicke δR zwischen 22 und 60 studiert.Die unter Berücksichtigung des Salzeffektes korrigierten Geschwindigkeitskonstanten stimmen mit den von Eigen und Mitarbeiter auf nicht elektrochemischem Wege gemessenen innerhalb der Fehlergrenzen gut überein.
Diffusionsuntersuchungen am System AgCl‐In in verschiedenen In‐Konzentrationsbereichen
Authors: Frisch J. , Hensel V. , Wolf G. 
Published: November 2023

AbstractDie Diffusion von In in reinen und In‐dotierten AgCl‐Einkristallen wurde bei kleinen In‐Konzentrationen (cIn < 10−4 mol%) in Abhängigkeit von der Temperatur mit der Tracer‐Methode (In114m) untersucht. Für die Messungen im Konzentrationsbereich bis zu 2mol° In erfolgte die Diffusion in nichtdotierte AgCl‐Kristalle aus der Gasphase; die Konzentrationsverteilung der Indiumionen wurde dabei über eine Aktivierungsanalyse aufgenommen. Sämtliche experimentellen Ergebnisse lassen sich unter der Annahme der Zweiwertigkeit des Indiums und mit einem von Lidiard angegebenen Ansatz für einen Lückenkomplexmechanismus interpretieren; dabei wurden die Experimente bei den höheren Konzentrationen unter Berücksichtigung einer Debye‐Hückel‐Wechselwirkung ausgewertet.
The Enthalpy Change Due to Uptake of the Nonmetallic Component X by an Ionic Compound AX as a Function of the Activity of X
Authors: Wagner Carl 
Published: November 2023

AbstractThis paper comprises calculations of the enthalpy change ΔH due to uptake of the nonmetallic component X by an ionic compound AX as a function of the activity ax. At ideal stoichiometric composition ΔH is negative. At increasing activity ax, i.e., increasing metal deficit δ, ΔH becomes less negative. Eventually, δH reaches a maximum value followed by a decrease to more negative values if associates of cation vacancies and holes, i.e. non‐ionized cation vacyncies are formed. Accordingly, the heat release due to uptake of X may reach a minimum as has been observed for UO2 by Gerdanian et al.
Associative and Non‐Associative Ion Pair Formation by Fast Atoms
Authors: Wexler S. 
Published: November 2023

AbstractThis review discusses recent results on collision processes of accelerated atoms which lead to ion production. Five general classes of reactions are described ‐ collision‐induced dissociative ion pair formation (polar dissociation), electron transfer, associative ionization, reactive (rearrangement) ionization, and simple collisional ionization. The review is restricted to ion product reactions that have been studied in molecular beam experiments in which two neutral species collide with relative energies up to 20 eV, and the endoergicity of the reaction is provided by the kinetic energy of one of the partners. The accelerating techniques capable of producing beams of fast atoms and molecules in this important energy region are described.Characteristics of such reactions are the cross sections for the various reaction channels and their dependences on the relative energy (i.e., the excitation functions), the behavior of the cross section near threshold, the relative importance of translational and internal energy in promoting the reaction, and the dynamics of the collisions as revealed by the angular distributions of the products. Illustrative results on these properties are presented. The polar dissociation of the thallium halides by accelerated Xe and Kr atoms, and the dynamics of a number of reactions of fast metal and non‐metal atoms with several molecules are described in detail.
Collision Induced Dissociation of Ions
Authors: Los J. 
Published: November 2023

AbstractThe study of collision induced dissociation by means of high resolution mass spectrometry has developed in recent years to a method which yields detailed information on the collisional dissociation of molecules. The method is based upon the phenomenon of Aston bands appearing in mass spectra. Introduction of a collision chamber in the drift region between ion source and magnetic analyser localizes the place where collisional dissociation takes place, and offers the possibility to measure the doubly differential cross section for this process with respect to velocity and scattering angle of the charged fragment; integrated however, over all impact parameters. At the energies considered (keV range) these measurements then yield detailed information about the influence of angular position and internuclear distance on collisional excitation of molecules.The experimental results on collision induced dissociation of H+2 and HeH+ are discussed in connection with the existing theoretical approaches. It is shown that there is experimental evidence that the different mechanisms as they are defined by Durup contribute to the collision induced dissociation of these molecules. More experimental work, however, has to be performed in order to disentangle completely the different contributions to collisional dissociation.
Fluorescence and Absorption Spectra of Sterically Hindered Arylethylenes in the Neat Glassy State
Authors: Fischer G. , Fischer E. , Stegemeyer H. 
Published: November 2023

AbstractThe fluorescence spectra of some sterically hindered arylethylenes in the neat glassy state show a considerable blue shift with respect to those of the crystalline solids, while the absorption is shifted to the red. The small Stokes shift and the reduced half width of the emission band indicate that the emitting excited state is much less relaxed in the glass than in the crystal. The restriction of the relaxation process is discussed in terms of the properties of the disordered glassy state.
Promotion of Direct Electron Transfer to Cytochrome c by Functionalized Thiophene‐based Conducting Polymers
Authors: Sáenz‐Espinar María J. , Quintero‐Jaime Andrés F. , Gamero‐Quijano Alonso , Montilla Francisco , Huerta Francisco 
Published: November 2023

AbstractControlling direct electron transfer (DET) to redox proteins is of great interest for fundamental studies on biochemical processes and the development of biotechnological devices, such as biosensors or enzymatic fuel cells. Cytochrome c is a classical model protein for studying DET reactions that plays a key role in the onset of cellular apoptosis and the mitochondrial respiratory chain. In this contribution, we explored DET between cyt c and conducting polymers bearing the chemical structure of thiophene, specifically PEDOT, and its OH‐containing derivative, PHMeEDOT. The combination of electrochemistry and in situ FTIR spectroscopy allowed us to gain more insight into the inner mechanism of DET at physiological pH. Hydrophilic interactions favour the correct orientation of the heme crevice of cytochrome c towards the polymer surface. When a positive charge is injected into the conducting polymer, the increasing electrostatic repulsion between protein and surface induces the desorption of lysine residues near the heme group and stimulates protein flipping. This effect was more pronounced at PEDOT‐ than PHMeEDOT‐modified electrodes since the latter shows stronger interactions with lysine residues, partially hindering protein rotation at moderate potential. The potential‐induced reorientation process was similar on both polymer surfaces, only at high positive potentials.
Unraveling the Push‐Pull Effect in Acenes, Polyenes and Polyynes
Authors: Wieczorkiewicz Paweł A. , Shahamirian Mozhgan , Kupka Teobald , Makieieva Natalina , Krygowski Tadeusz M. , Szatylowicz Halina 
Published: November 2023

AbstractSubstituent effects (SEs) are fundamental for predicting molecular reactivity, while polyene, polyyne and acene derivatives are precursors to compounds with diverse applications. Computations were performed for Y‐R‐X systems, where reaction sites Y=NO2 and O−, substituents X=NO2, CN, Cl, H, OH, NH2, and spacers R=polyene, polyyne (n=1‐5, 10 repeating units) and acene (up to tetracene). The cSAR (charge of the substituent active region) approach allowed to present, for the first time, quantitative relations describing the spacer's electron‐donating and withdrawing properties as a function of n and the spacer type. The electronic properties of the X substituents depend on the type of spacer, its length and the Y group, which is an example of the reverse SE. To describe how the SE between Y and X weakens with n, two approaches were compared: cSAR and SESE (SE stabilization energy). The EDDB (electron density of delocalized bonds) characterize changes in electron delocalization in spacers due to the SE. A new approach – EDDB differential maps – allow to extract the effect of X substitution on the electron delocalization. The charges at spacer's C atoms correlate with cSAR; changes in the slopes confirm the charge transfer by resonance.
Enhancing the Potential of Fused Heterocycle‐Based Triarylhydrazone Photoswitches
Authors: Hegedüsová Lea , Blaise Nadine , Pašteka Lukáš F. , Budzák Šimon , Medveď Miroslav , Filo Juraj , Mravec Bernard , Slavov Chavdar , Wachtveitl Josef , Grabarz Anna M. , Cigáň Marek 
Published: November 2023

AbstractTriarylhydrazones represent an attractive class of photochromic compounds offering many interesting features including high molar absorptivity, good addressability, and extraordinary thermal stability. In addition, unlike most other hydrazone‐based photoswitches, they effectively absorb light above 365 nm. However, previously prepared triaryhydrazones suffer from low quantum yields of the Z→E photoisomerization. Here, we have designed a new subclass of naphthoyl‐benzothiazole hydrazones that balance the most beneficial features of previously reported naphthoyl‐quinoline and benzoyl‐pyridine triarylhydrazones. These preserve the attractive absorption characteristics, exhibit higher thermal stability of the metastable form than the former and enhance the rate of the Z→E photoisomerization compared to the later, as a result of the weakening of the intramolecular hydrogen bonding between the hydrazone hydrogen and the benzothiazole moiety. Introducing the benzothiazole motif extends the tunability of the photochromic behaviour of hydrazone‐based switches.
Sulfur‐ and Amine‐ Promoted Multielectron Autoredox Transformation of Nitromethane: Multicomponent Access to Thiourea Derivatives
Authors: Phaenok Supasorn , Nguyen Le Anh , Soorukram Darunee , Nguyen Thi Thanh Tam , Retailleau Pascal , Nguyen Thanh Binh 
Published: November 2023

AbstractThiourea derivatives are in‐demand motifs in organic synthesis, medicinal chemistry and material science, yet redox methods for the synthesis that start from safe, simple, inexpensive and readily available feedstocks are scarce. In this article, we disclose the synthesis of these motifs using elemental sulfur and nitromethane as the starting materials. The method harnesses the multi‐electron auto‐redox property of nitromethane in the presence of sulfur and amines, delivering thiourea products without any added oxidant or reductant. Extension of this reaction to cyclizable amines and/or higher homologues of nitromethane led to a wide range of nitrogen heterocycles and thioamides. Operationally simple, the reactions are scalable, tolerate a wide range of functional groups, and can be employed for the direct functionalization of natural products. Mechanistically, the nitro group was found to act as an oxidant leaving group, being reduced to ammonia whereas sulfur, along with the role of a sulfur building block for the thiocarbonyl group, behaved as a complementary reductant, being oxidized to sulfate.
The brightness of chromatic stimuli
Authors: Hellwig Luke , Stolitzka Dale , Fairchild Mark D. 
Published: November 2023

AbstractWe present the results of a series of three brightness‐matching experiments which include a key refinement in this established psychophysical method. Constraining the chroma difference between pairs of stimuli matched in brightness allows us to use a novel calculus‐based approach to building a model of the brightness of chromatic visual stimuli and the Helmholtz‐Kohlrausch effect. The proposed models, compatible with the CIECAM16 color appearance model and CIELAB color space, are compared to other models of the Helmholtz‐Kohlrausch effect on these data and other past brightness‐matching studies. The proposed CIECAM16‐based model demonstrates the overall best performance on predicting the Helmholtz‐Kohlrausch effect in four newer data sets but overpredicts the weaker effect reported in three older data sets. The potential experimental factors in this divide between new and old studies are also discussed.
Homogeneous Dephasing in Photosynthetic Bacterial Reaction Centers: Time Correlation Function Approach
Authors: Toutounji Mohamad 
Published: November 2023

AbstractA new tractable linear electronic transition dipole moment time correlation function (ETDMTCF) that accurately accounts for electronic dephasing, asymmetry, and width of 1‐phonon profile, which the zero‐phonon line (ZPL) contributes to it, in Rhodopseudomonas viridis bacterial reaction center is derived. This time correlation function proves to be superior to other frequency‐domain expressions in case of strong electron‐phonon coupling (which is often the case in bacterial RCs and pigment‐protein complexes), many vibrational modes involved, and high temperature, whereby more vibronic and electronic (sequence) transitions would arise. The Fourier transform of this ETDMTCF leads to asymmetric multiphonon profiles composed of Lorentzian distribution and Gaussian distribution on the high‐ and low‐energy sides, respectively, whereby the overtone widths fold themselves with that of the one‐phonon profile. This ETDMTCF also features expedient computation in large systems using asymmetric phonon profiles to account correctly for dephasing and pigment‐protein interaction (electron‐phonon coupling). The derived ETDMTCF allows computing all nonlinear optical signals in both time and frequency domains, through the nonlinear dipole moment time correlation functions (as guided by nonlinear optical response theory) in line with the eight Liouville space pathways. The linear transition dipole moment time correlation function is of a central value as the nonlinear transition dipole moment time correlation function is expressed in terms of the linear transition dipole moment time correlation function, derived herein. One of the great advantages of presenting this ETDMTCF is its applicability to nonlinear transition dipole moment time correlation functions in line with the eight Liouville space pathways needed in computing nonlinear signals. As such, there is more to the utility and applicability of the presented ETDMTCF besides computational expediency and efficiency. Results show good agreement with the reported literature. The intimate connection between a one‐phonon profile and the corresponding bath spectral density in photosynthetic complexes is discussed.
Polymers with Circularly Polarized Luminescent Properties: Design, Synthesis, and Prospects
Authors: Yu Jia‐Xin , Duan Bing‐Hui , Chen Zheng , Liu Na , Wu Zong‐Quan 
Published: November 2023

AbstractChiral materials with circularly polarized luminescence (CPL) have garnered significant attention owing to their distinctive luminescent properties and wide array of applications. CPL enables the selective emission of left and right circularly polarized light. The fluorescence quantum yield and dissymmetry factor play pivotal roles in the generation of CPL. Helical polymers exhibit immense promise as CPL materials due to their inherent chirality, structural versatility, modifiability, and capacity to incorporate diverse chromophores. This Review provides a brief review of the synthesis of CPL materials based on helical polymers. The CPL can be realized by aggregation‐induced CPL of non‐emissive helical polymers, and helices bearing chromophores on the pendants and on the chain end. Furthermore, future challenges and potential applications of CPL materials are summarized and discussed.
Age‐stratified risk factors of re‐intervention for uterine fibroids treated with high‐intensity focused ultrasound
Authors: Tang Neng‐huan , Fang Chun‐ling , Hu Wen‐hao , Tian Ling , Lin Chuan , Hu Hui‐quan , Shi Qiu‐ling , Xu Fan 
Published: November 2023

AbstractObjectiveTo estimate the rate and risk factors of re‐intervention for patients with uterine fibroids (UFs) undergoing high‐intensity focused ultrasound (HIFU) at different age distributions.MethodA retrospective cohort study was conducted in Nanchong Central Hospital, recruiting a total of 672 patients with UFs undergoing HIFU from June 2017 to December 2019. Using univariate and multivariate logistic regression, risk factors for re‐intervention were assessed.ResultsAmong 401 patients with UFs who completed the follow‐up visits (median 47 months, range 34–61), 50 (12.46%) patients underwent re‐intervention (such as high‐intensity focused ultrasound, uterine artery embolization, myomectomy and hysterectomy). In the different age distributions, the re‐intervention rate was 17.5% (34/194) in patients aged <45 years and 7.7% (16/207) in those aged ≥45 years. Regarding the younger patient group (aged <45 years), hypo‐ or iso‐intensive fibroids in T2‐weighted magnetic resonance imaging (T2WI) intensity may elevate the risk of re‐intervention for UFs (odds ratio [OR] 2.96, 95% confidence interval [CI] 1.37–6.62; P = 0.007). Among the older patient group (aged ≥45 years), preoperative anemic patients had an increased risk of re‐intervention compared with those without anemia (OR 3.30, 95% CI 1.01–10.37; P = 0.041).ConclusionThe re‐intervention rate of HIFU decreased with increasing age. Among those aged <45 years, T2WI intensity was the independent risk factor for re‐intervention, and among those aged ≥45 years, preoperative anemic status may be related to re‐intervention outcome.