Analogous Transformations Research Articles

Understanding the Reactivity and Selectivity of Oxazaborolidium Ion-Catalyzed Diels-Alder Reactions Involving Cyclobutenones as Dienophiles.

The poorly understood factors controlling the reactivity and selectivity (both stereo- and enantioselectivity) of catalyzed Diels-Alder reactions involving cyclobutenones as dienophiles have been analyzed in detail by means of Density Functional Theory calculations. To this end, the reactions with cyclopentadiene and furan as dienes and 3-(methoxycarbonyl)cyclobutenone catalyzed by Corey's chiral oxazaborolidium ion (COBI) have been selected and compared to their analogous uncatalyzed transformations. The combined Activation Strain Model of reactivity and Energy Decomposition Analysis methods have been used to quantitatively understand the acceleration and selectivity induced by the catalyst in this reaction.

HFIP-driven Schmidt-type reaction enables chromone-3-carbonitriles and its applications.

Chromone-3-carbonitrile has been extensively studied in a panel of high-value transformations. However, existing protocols for the synthesis of this scaffold are often constrained by the structure of the starting materials and harsh conditions. To address these issues, we present a novel strategy that HFIP (hexafluoroisopropanol)-driven strategy, enables chromone-3-carbonitriles synthesis without undesirable side reactions. This protocol features readily available feedstocks, mild conditions, catalytic amount of acid and good to excellent yields. The utility of this chemistry is further demonstrated by amenable modifications of chromone-pyrimidines and imidazoles. Moreover, the analogous transformation of aldehydes is successfully constructed to achieve useful compounds such as 2-hydroxybenzonitriles, heterocyclic nitriles, and α, β-unsaturated nitriles. The HFIP-driven strategy offers an interesting access to different types of nitriles in a sustainably manner.

New Antibacterial and Antioxidant Chitin Derivatives: Ultrasonic Preparation and Biological Effects.

This work focuses on the first use of ultrasonic phenol-ene coupling as a polymer analogous transformation. The ultrasonic reaction was introduced into chitin chemistry, resulting in the fast and convenient preparation of new water-soluble cationic chitin derivatives. Since water-soluble derivatives of fully deacetylated chitin are poorly described in the literature, the synthesis of each new type of these derivatives is a significant event in polysaccharide chemistry. Polycations, or cationic polymers, are of particular interest as antibacterial agents. Consequently, the resulting polymers were tested for their antibacterial activity and toxicity. We found that the highly substituted polymer of medium molecular weight exhibited the most pronounced in vitro antibacterial effect. We prepared nanoparticles using the ionic gelation technique. The most effective in vitro antibacterial chitin-based systems were tested in vivo in rats. These tests demonstrated outstanding antibacterial effects combined with an absence of toxicity. Additionally, we found that the resulting polymers, unlike their nanoparticle counterparts, also exhibited strong antioxidant effects. In summary, we demonstrated the effectiveness of ultrasound in polymer chemistry and highlighted the importance of the sonochemical approach in the chemical modification of polysaccharides. This approach enables the synthesis of derivatives with improved physicochemical and biological properties.

COMPUTATIONAL ANALYSIS OF NONLINEARIZED THERMAL RADIATION & LORENTZ FORCE ON UNSTEADY FLOW OF NON-NEWTONIAN FLUID IN POROUS MEDIUM

An extensive analysis of nonlinearized thermal radiation & Lorentz force on an unsteady flow of Non-Newtonian fluid taking the Maxwell model over a permeable nonuniform stretchable sheet in a porous media has been presented. Appropriate analogous transformations are introduced to develop the ordinary differential equations from the fluid flow governing equations. Numerical method Lobatto IIIa is used to solve these ODEs and programmed in mathematical software MATLAB to obtain the graphical and numerical details. The effectiveness of non-linearity in thermal radiation, unsteadiness of the flow and magnetic field on Nusselt number, skin friction, heat & fluid motion are tabulated and represented in graphs with an elaborate discussion of the consequences. It is found that the Lorentz force and nonlinearity in thermal radiation have an adverse impression on the heat propagation throughout the flow. Further, a comparative inspection is also carried out proving the relevance of the current technique.

“The Trees Got Their Own Ways to Hurt Us”: Entangled Bodies and Fragile Flesh in M.R. Carey’s "The Book of Koli" (2020)

There is a post-apocalyptic England teeming with violent plants, where one break in the clouds could wake the trees around you, condemning you to become sustenance for thirsty roots. This is the speculative future of M.R. Carey’s speculative young adult novel, The Book of Koli, where humans struggle to adapt to their new role in this speculative future and plants pose an ever-growing threat. In this article, I analyse how The Book of Koli engages with, what I term, “plant flesh,” through the analogous transformations of humans and plants. Plant flesh is a development of Michael Marder’s “grafts,” where he suggests that grafts are an expression of proliferation for both plants and flesh. With grafts, Marder illustrates the vegetality of flesh; with plant flesh, I illustrate both the vegetality of flesh and the fleshiness of the vegetal. Plant flesh, then, becomes a term of indistinction (as per Matthew Calarco), where, through plant flesh, we can begin to trace the ways that humans and animals are like plants. In The Book of Koli’s young adult context, plant flesh’s indistinction captures the shared and necessary – but oftentimes violent – transformation of flesh, as teen protagonist, Koli, transitions into adolescence alongside genetically modified plants and their evolution into speculative monstrosities. Through theoretical discussions and close readings, I argue that explorations of plant flesh in The Book of Koli serve to demonstrate both the shared, violent transformations of plant and human flesh and the indistinction that such transformations encourage between the adolescent Koli and the ever-evolving plants. The Book of Koli’s speculative young adult journey, then, with its botanical threats and adolescent transformations, makes apparent the indistinct zones that can emerge, when we tend to the entangled bodies and fragile flesh of both plants and humans.

Pressure Induces Six-fold Coordination for the Lighter Pnictides Phosphorus and Arsenic Triiodide.

In this study, we employ an evolutionary algorithm in conjunction with first-principles density functional theory (DFT) calculations to comprehensively investigate the structural transitions, electronic properties, and chemical bonding behaviors of XI3 compounds, where X denotes phosphorus (P) and arsenic (As), across a range of elevated pressures. Our computational analyses reveal a distinctive phenomenon occurring under compression, wherein the initially trigonal structures of PI3 (P 63) and AsI3 (R-3) undergo an intriguing transformation, leading to the emergence of six-coordinated monoclinic phases (C2/m) at 6 GPa and 2 GPa for PI3 and AsI3, respectively. These high-pressure phases exhibit their stability up to 10 GPa for PI3 and 12 GPa for AsI3. Notably, the resulting structures at elevated pressures bear striking resemblance to the widely recognized six-coordinated octahedral BiI3 crystal configuration observed at ambient conditions. Our investigation further underscores the pivotal role of pressure-induced reactivity of the lone-pair electrons in PI3 and AsI3, facilitating their enhanced stereochemical reactivity and thereby enabling higher six-fold coordination. Complementary analyses employing electron localization function (ELF) and density of states (DOS) effectively delineate the progression towards augmented coordination in PI3 and AsI3 with increasing pressure. While the phenomenon of heightened coordination is conventionally associated with heavier pnictide iodides such as SbI3 and BiI3 under ambient conditions due to heightened ionic character and relativistic effects in bismuth (Bi) and antimony (Sb), our findings accentuate that analogous structural transformations can also be induced in lighter elements like phosphorus (P) and arsenic (As) under the influence of pressure.

The local atomic and electronic structure of quasicrystal i-Al65Cu23Fe12 powder

This work presents an experimental and theoretical study of the atomic and electronic structures of the icosahedral Al65Cu23Fe12 quasicrystalline (QС) powder. The i-Al65Cu23Fe12 QС powder was investigated using X-ray diffraction, scanning electron microscopy, Mössbauer spectroscopy, X-ray absorption spectroscopy (XANES and EXAFS) and X-ray photoelectron spectroscopy. It was found that the i-Al65Cu23Fe12 quasicrystal surface consisted of an oxidized shell of Al2O3 and Cu2O, whereas the bulk fraction consisted of icosahedral Al65Cu23Fe12 quasicrystal and cubic β-Al(Cu0.5Fe0.5) phases. The proposed theoretical model of the structure of i-Al65Cu23Fe12 QC, based on the transformation of the crystalline analogue of Al7Cu2Fe, has good agreement with the experimental structural data obtained from EXAFS and XANES analysis. The electronic structure of the top of the valence band and the bottom of the conduction band of the i-Al65Cu23Fe12 QC was investigated using X-ray photoelectron spectroscopy, analysis of XANES, and ab initio calculations.

Chemo-, regio-, and stereoselective tetrafunctionalization of fluoroalkynes enables divergent synthesis of 5-7-membered azacycles.

Alkyne annulation has been widely used in organic synthesis for the construction of azacycles with unique structural and physicochemical properties. However, the analogous transformation of fluoroalkynes remains a challenge and has seen limited progress. Herein we report a 1,2,3,4-tetrafunctionalization of polyfluoroalkynes for the divergent construction of 5-7-membered (E)-1,2-difluorovinyl azacycles. The use of the fluorine atom as a detachable "activator" not only obviates the use of any transition metal catalysts and oxidizing reagents, but also ensures the [3-5 + 2]-annulation and defluorinative functionalization of fluoroalkynes with high chemo-, regio-, and stereoselectivities. This method exhibits a broad substrate scope, good functional group tolerance, and excellent scalability, providing a modular platform for accessing fluorinated skeletons of medicinal and biological interest. The late-stage modification of complex molecules, the multi-component 1,2-diamination of fluoroalkyne, and the synthesis of valuable organofluorides from the obtained products further highlight the real-world utility of this fluoroalkyne annulation technology.

Conformation-aggregation interplay in the simplest aliphatic ethers probed under high pressure.

The structures of the simplest symmetric primary ethers [(CnH2n+1)2O, n = 1-3] determined under high pressure revealed their conformational preferences and intermolecular interactions. In three new polymorphs of diethyl ether (C2H5)2O, high pressure promotes intermolecular CH...O contacts and enforces a conversion from the trans-trans conformer present in the α, β and γ phases to the trans-gauche conformer, which is higher in energy by 6.4 kJ mol-1, in the δ phase. Two new polymorphs of dimethyl ether (CH3)2O display analogous transformations of the CH...O bonds. The crystal structure of di-n-propyl ether (C3H7)2O, determined for the first time, is remarkably stable over the whole pressure range investigated from 1.70 up to 5.30 GPa.

Reflection of one episode of Georgian history in the 14th century Syrian chronicle – „History of Mar Yahbalaha and Bar Sauma“

The Catholic Western world exhibited a heightened interest in establishing contact with unfamiliar populations following theemergence of the Mongols on the global stage. The Papal authority entertained aspirations of effecting the conversion of the Tatars to Catholic Christianity through the deployment of missionary endeavors. The Catholic Church embarked on a vigorous proselytization campaign within the Mongolian uluses. In pursuit of this objective, Georgia, distinguished by its amenable disposition toward Franciscan and Dominican missionaries, emerged as a strategically valuable foothold for this mission. Conversely, the Mongols made efforts to persuade the Papal authority of their earnestness, with the intention of forming an anti-Egyptian coalition. Following this goal, they dispatched envoys to Western regions, often including Christians, to engage in negotiations; among these envoys were the Nestorians, who had established themselves within the Tatar domain long before andpropagated the heretical beliefs censured in Western Europe. Rabban Sauma, a notable itinerant clergyman, was among those who embarked on a journey to the Western world in the years 1287-88. He attained such a distinguished accolade not solely due to his proficient mastery of the Latin language, but also by virtue of his sanctified actions. These included a life of asceticism, enduring numerous trials, and an ardent yearning to undertake a pilgrimage to Jerusalem. Together with Rabban Sauma, his disciple, the future patriarch Yahbalaha III, also embarked on the most difficult path with the desire of repentance in about 1275-77. It was within the course of this expedition that the monks arrived in Georgia, where they were informed that, notwithstanding the benevolence of the Ilkhan Khan-Abaqa, they would encounter impediments preventing them from advancing further on their journey. A chronicle attributed to an anonymous author from the first half of the 14th century documents that the monks’ travel to Jerusalem was thwarted due to the presence of marauders and malefactors within the territory of Georgia. The apostasy of Samtskhe from the the Ilkhan rulers must have been a contributing factor in the situation. The resistance of Georgians must have been caused by the earthquake that happened on April 10, 1275. The latter, along with the rest of Georgia, especially affected Samtskhe. The substantial loss of life, widespread damage to infrastructure and edifices, coupled with the imposition of Mongol levies and military obligations, likely contributed analogous transformations within Georgia.This information brought into the scientific area and its analysis is of paramount importance, because the chronicler, in his accounts,primarily addresses the political ramifications of the earthquake and notes the departure of father and son-Sargis and Beka, from allegiance to the Ilkhan rulers. The excerpt from Syrian anonymous author’s chronicle, as sited in the article, serves to complement the chronicler’s narrative by shedding light on the pertinent social aspects of the earthquake consequences.

Recent Advances in Nickel Catalyzed Carbonylative Reactionsviathe Insertion of Carbon Monoxide†

Comprehensive SummaryCarbonyl compounds have attracted considerable attention due to their extensive applications in drug discovery. Furthermore, they are important synthetic intermediates for the construction of carbon‐carbon and carbon‐heteroatom bonds. Transition‐metal‐catalyzed carbonylation via the insertion of CO is one of the most efficient and straightforward strategies to access carbonyl compounds. However, most of the transition‐metal‐catalyzed carbonylative reactions require expensive and toxic noble‐metal catalysts. Therefore, there is a growing demand for the exploration of nickel‐catalyzed carbonylative reactions via the insertion of CO due to the earth abundance and low cost of nickel. Compared with the well‐established palladium‐catalyzed carbonylative reactions, nickel‐catalyzed analogous transformations have been relatively underdeveloped. This is primarily because CO strongly binds to nickel, often resulting in catalyst poisoning. In recent years, some research groups have focused on using CO surrogates or NN2pincer nickel catalyst to circumvent the formation of Ni(CO)4. Nickel‐catalyzed carbonylation has been applied in the construction of carbonyl‐containing compounds, such as ketones, carboxylic acids, thioesters, acyl chloride and carboxamides.

Mechanistic Insights into the DABCO-Catalyzed Cloke-Wilson Rearrangement: A DFT Perspective.

The mechanism and selectivity patterns of the DABCO-catalyzed Cloke-Wilson rearrangement were computationally studied in detail using density functional theory calculations. Our computations suggest that the process occurs stepwise involving the initial ring opening of the cyclopropane promoted by a DABCO molecule followed by a ring-closure reaction of the readily formed zwitterionic intermediate. The regioselectivity of the initial nucleophilic ring-opening step strongly depends on the nature of the substituent attached to the cyclopropane moiety. The physical factors governing the preference for the more sterically hindered C2 (tertiary) position have been quantitatively analyzed by applying the combined activation strain model-energy decomposition analysis method. In addition, our calculations revealed a new mechanism for the analogous transformation involving vinylcyclopropanes consisting of an initial SN2' ring-opening process followed by a 5-exo-trig cyclization step, which proceeds without facial selectivity.

Photocatalytic Generation of Divalent Lanthanide Reducing Agents.

Divalent lanthanide (Ln) compounds are excellent reducing agents with unique reactivity profiles. These reagents are typically used in superstoichiometric amounts, often in combination with harmful additives. Reactions catalytic in Ln(II) reagents that retain the reactivity and selectivity of the stoichiometric transformations are currently lacking due to the absence of effective and selective methods to form reactive Ln(II) species from stable precursors. Here, active Ln(II) is generated from a Ln(III) precursor through reduction by a photoexcited coumarin or carbostyril chromophore, which, in turn, is regenerated by a sacrificial reductant. The reductant can be metallic (Zn) or organic (amines) and can be used in strictly stoichiometric amounts. A broad range of reactions, including C-halogen, C═C, C═X (X = O, N), P═O, and N═N reductions, as well as C-C, C-X (X = N, S, P), and N-N couplings were readily carried out in yields and selectivities comparable to or better than those afforded by the analogous stoichiometric transformations. The reaction outcomes could be altered by changing the ligand or the lanthanide or through the addition of environmentally benign additives (e.g., water). EPR spectroscopy supported the formation of both Ln(II) and oxidized chromophore intermediates. Taken together, these results establish photochemical Ln(II) generation as a powerful strategy for rendering Ln(II)-mediated reactions catalytic.

A multi-stage, first-order phase transition in LaFe11.8Si1.2: Interplay between the structural, magnetic, and electronic degrees of freedom

Alloys with a first-order magnetic transition are central to solid-state refrigeration technology, sensors and actuators, or spintronic devices. The discontinuous nature of the transition in these materials is a consequence of the coupling between the magnetic, electronic, and structural subsystems, and such transition can, in principle, cross several metastable states, where at one point, the transition takes place within the magnetic subsystem, while at another, the changes occur in the structural or electronic subsystems. To address this issue, we conducted simultaneous measurements of the macroscopic properties—magnetization, temperature change of the sample, longitudinal, and transversal magnetostrictions—to reveal the rich details of the magneto-structural, first-order transition occurring in the prototypical alloy LaFe11.8Si1.2. We found that the transition does not complete in one but in two distinct stages. The presence of the intermediate state changes the potential-energy landscape, which then impacts strongly on the width of the hysteresis associated with the first-order transition. We complement these findings with experiments on the atomistic scale, i.e., x-ray absorption spectroscopy, x-ray magnetic circular dichroism, and Mössbauer spectroscopy, and then combine them with first-principles calculations to reveal the full complexity and two-stage nature of the transition. This new approach can be successfully extended to a large class of advanced magnetic materials that exhibit analogous transformations.

Charmm2gmx: An Automated Method to Port the CHARMM Additive Force Field to GROMACS.

CHARMM is one of the most widely used biomolecular force fields. Although developed in close connection with a dedicated molecular simulation engine of the same name, it is also usable with other codes. GROMACS is a well-established, highly optimized, and multipurpose software for molecular dynamics, versatile enough to accommodate many different force field potential functions and the associated algorithms. Due to conceptional differences related to software design and the large amount of numeric data inherent to residue topologies and parameter sets, conversion from one software format to another is not straightforward. Here, we present an automated and validated means to port the CHARMM force field to a format read by the GROMACS engine, harmonizing the different capabilities of the two codes in a self-documenting and reproducible way with a bare minimum of user interaction required. Being based entirely on the upstream data files, the presented approach does not involve any hard-coded data, in contrast with previous attempts to solve the same problem. The heuristic approach used for perceiving the local internal geometry is directly applicable for analogous transformations of other force fields.

Semantic and structural challenges of translating modern English agro-engineering terminology into Ukrainian

The study analyzes semantic and structural peculiarities of translating modern English agro-engineering terminology. Agro-engineering terms represent the up-to-date level of agriculture development noted for advanced mechanization, application of various technical processes, new technologies, etc., this causing additional translation problems. Besides, agricultural terminology encapsulates field-specific lexis as well as mathematical, mechanical, biological and general scientific terms. Translation difficulties are closely related to lingual characteristics of agro-engineering terms (structural peculiarities, synonymy, homonymy). Playing a significant role in forming this segment of professional lexicon, multi-component units are difficult to translate due to their length and non-prepositional bonds in most cases. The main research methods include comparative and contrastive analysis as well as the quantitative method. The results obtained reveal that a variety of techniques applied to translating English agro-engineering terms into Ukrainian include equivalence, analogue, descriptive techniques, transliteration, grammatical and lexical transformations. Yet, the most frequent technique is equivalence. Application of different translation techniques in multicomponent phrases can cause inconsistences in the number of components in a terminological phrase in a target language. The authors suggest an algorithm of English-Ukrainian translation of agro-engineering multicomponent terms. The paper is intended for a wide range of specialists interested in translating agro-engineering texts, teaching ESP, students of translation departments and experts in the relevant field of knowledge.

Synthesis of 2-Cyanomethyl Indane Derivatives via Pd-Catalyzed Alkene Difunctionalization Reactions of Alkyl Nitriles.

The synthesis of indanes bearing substituted cyanomethyl groups at C2 is achieved through Pd-catalyzed coupling reactions between 2-allylphenyl triflate derivatives and alkyl nitriles. Related partially saturated analogues were generated from analogous transformations of alkenyl triflates. The use of a preformed BrettPhosPd(allyl)(Cl) complex as a precatalyst was essential for the success of these reactions.

Enantioselective Synthesis of α-Alkenylated γ-Lactam Enabled by Ni-Catalyzed 1,4-Arylcarbamoylation of 1,3-Dienes

Enantioselective Synthesis of α-Alkenylated γ-Lactam Enabled by Ni-Catalyzed 1,4-Arylcarbamoylation of 1,3-Dienes

Metasurface for oscillatory spin splitting along the optical path

Spin splitting of light originates from the interplay between the polarization and spatial degrees of freedom as a fundamental constituent of the emerging spin photonics, providing a prominent pathway for manipulating photon spin and developing exceptional photonic devices. However, previously relevant devices were mainly designed for routing monotonous spin splitting of light. Here, we realize an oscillatory spin splitting of light via metasurface with two channel Pancharatnam–Berry phases. For the incidence of a linearly polarized light, the concomitant phases arising from opposite spin states transition within pathways of the metasurface induce lateral spin splitting of light with alternately changed transport direction during beam guiding. We demonstrate the invariance of this phenomenon with an analogous gauge transformation. This work provides a new insight on steering the photon spin and is expected to explore a novel guiding mechanism of relativistic spinning particles, as well as applications of optical trapping and chirality sorting.

Environmental Fate of Cl-PFPECAs: Predicting the Formation of PFAS Transformation Products in New Jersey Soils.

Although next-generation per- and polyfluorinated substances (PFAS) were designed and implemented as safer and environmentally degradable alternatives to "forever" legacy PFAS, there is little evidence to support the actual transformation of these compounds and less evidence of the safety of transformed products in the environment. Multiple congeners of one such PFAS alternative, the chloro-perfluoropolyether carboxylates (Cl-PFPECAs), have been found in New Jersey soils surrounding a manufacturing facility. These compounds are ideal candidates for investigating environmental transformation due to the existence of potential reaction centers including a chlorinated carbon and ether linkages. Transformation products of the chemical structures of this class of compounds were predicted based on analogous PFAS transformation pathways documented in peer-reviewed literature. Potential reaction products were used as the basis for high-resolution mass-spectrometric suspect screening of the soils. Suspected transformation products of multiple congeners, the Cl-PFPECAs, including H-PFPECAs, epox-PFPECAs, and diOH-PFPECAs, were tentatively observed in these screenings. Although ether linkages have been hypothesized as potential reaction centers under environmental conditions, to date, no documentation of ether scission has been identified. Despite exhaustive scrutiny of the high-resolution data for our Cl-PFPECA-laden soils, we found no evidence of ether scission.