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Two closely related yet distinctly different cationic clusters, [Dy52Ni44(HEIDA)36(OH)138(OAc)24(H2O)30]10+ (1) and [Dy112Ni76(HEIDA)44(EIDA)24(IDA)4(OH)268(OAc)48(H2O)44]4+ (2) (HEIDA=N‐(2‐hydroxyethyl)iminodiacetate), each featuring a multi‐shell core of Platonic and Archimedean polyhedra, were obtained. Depending on the specific conditions used for the co‐hydrolysis of Dy3+ and Ni2+, the product can be crystallized out as one particular type of cluster or as a mixture of 1 and 2. How the reaction process was affected by the amount of hydrolysis‐facilitating base and/or by the reaction temperature and duration was investigated. It has been found that a reaction at a high temperature and/or for an extended period favors the formation of the compact and thermodynamically more stable 1, while a brief reaction with a large amount of the base is good for the kinetic product 2. By tuning these intertwining conditions, the reaction can be regulated toward a particular product. [ABSTRACT FROM AUTHOR]

The preparation of novel structures of light-diffusing particles is currently a research focus in the field of light-diffusing materials. This study, conducted by the common melt-blending process, controlled thermodynamic and kinetic factors to distribute smaller-sized organic silica bead (OSB) particles at the interface between a polycarbonate (PC) matrix and spherical island-phase styrene–acrylonitrile copolymer (SAN) for the in situ formation of compound eye-like microspheres with SAN as "large eyes" and OSBs as "small eyes". Through the multiple-scattering effects of these compound eye-like microspheres, these light-diffusing materials significantly improved the haze, scattering range, and light-shielding capabilities while maintaining high transmittance. Specifically, the PC/SAN-OSB light-scattering materials achieved a haze of 100% with an OSB content of only 0.17%, maintaining a transmittance of 88%. Compared with the PC/OSB system with the same level of haze, the addition of OSB was reduced by 88%. Therefore, this study achieved exceptionally effective light-diffusing materials through a simple, environmentally friendly, and low-cost preparation method, suitable for the scalable production of light-diffusing materials in new display and lighting fields. [ABSTRACT FROM AUTHOR]

This study analyzes the samarium diiodide‐promoted cyclizations of 5‐arylpentan‐2‐ones to dearomatized bicyclic products utilizing density functional theory. The reaction involves a single electron transfer to the carbonyl group, which occurs synchronously with the rate determining cyclization event, and a second subsequent proton‐coupled electron transfer. These redox reactions are accurately computed employing small core pseudo potentials explicitly involving all f‐electrons of samarium. Comparison of the energies of the possible final products rules out thermodynamic control of the observed regio‐ and diastereoselectivities. Kinetic control via appropriate transition states is correctly predicted, but to obtain reasonable energy levels the influence of the co‐solvent hexamethylphosphortriamide has to be estimated by using a correction term. The steric effect of the bulky samarium ligands is decisive for the observed stereoselectivity. Carbonyl groups in para‐position of the aryl group change the regioselectivity of the cyclization and lead to spiro compounds. The computations suggest again kinetic control of this deviating outcome. However, the standard mechanism has to be modified and the involvement of a complex activated by two SmI2 moieties is proposed in which two electrons are transferred simultaneously to form the new C−C bond. Computation of model intermediates show the feasibility of this alternative+ mechanism. [ABSTRACT FROM AUTHOR]

This article presents a comprehensive computational chemistry experiment designed for senior undergraduate students majoring in chemistry. The experiment utilizes quantum chemical calculations to study a typical Diels-Alder reaction found in organic chemistry textbooks. It provides a microscopic physical picture of the reaction process, as well as quantitative information on the thermodynamic and kinetic properties of the reaction, elucidating the fundamental concepts of thermodynamic control and kinetic control in chemical reactions. The objective of this experiment is to cultivate students' basic skills in using computational chemistry methods to investigate chemical problems and deepen their understanding of the relationship between molecular structure and properties. Additionally, the experiment serves as a specific example of dialectical materialism worldview and methodology education for students, emphasizing the importance of recognizing the universality of contradictions and developing the ability to analyze and solve practical chemical problems using a holistic and developmental perspective. [ABSTRACT FROM AUTHOR]

Control of the intermolecular aggregation of organic π‐conjugated molecules as chromophores is crucial for tuning their physical properties such as light absorption/emission, and energy and charge transfer. Lots of advances have been achieved in control of intermolecular aggregation of organic chromophores in solid states where an indefinitely large number of molecules are involved. However, much less understanding has been gained at a mesoscale of aggregates formed by well‐defined organization of a deterministic number of chromophores, which has been realized in natural photosynthetic systems but still remains rare in manmade materials. Here, we report both the kinetic and the thermodynamic control of the supramolecular aggregation of a near‐infrared cyanine dye, PPcy, and its derivatives confined in colloidal nanoparticles stabilized by surfactants in aqueous media. Our results demonstrate that both the aggregation number, the aggregation state and the optical properties of the PPcy chromophores are controllable through optimization of the alkyl and polymer chains tethered from PPcy, the effective concentration of the chromophore inside each particle, and the surfactants utilized to stabilize the colloids in water. [ABSTRACT FROM AUTHOR]

The folding of proteins into intricate three‐dimensional structures to achieve biological functions, such as catalysis, is governed by both kinetic and thermodynamic controls. The quest to design artificial enzymes using minimalist peptides seeks to emulate supramolecular structures existing in a catalytically active state. Drawing inspiration from the nuanced process of protein folding, our study explores the enzyme‐like activity of amphiphilic peptide nanosystems in both equilibrium and non‐equilibrium states, featuring the formation of supramolecular nanofibrils and nanosheets. In contrast to thermodynamically stable nanosheets, the kinetically trapped nanofibrils exhibit dynamic characteristics (e.g. rapid molecular exchange and relatively weak intermolecular packing), resulting in a higher hydrolase‐mimicking activity. We emphasize that a supramolecular microenvironment characterized by an optimal local polarity, microviscosity, and β‐sheet hydrogen bonding is conducive to both substrate binding and ester bond hydrolysis. Our work underscores the pivotal role of both thermodynamic and kinetic control in impacting biomimetic catalysis and sheds a light on the development of artificial enzymes. [ABSTRACT FROM AUTHOR]

Macrocyclic and medium‐sized ring ketones, lactones and lactams can all be made from common acryloyl imide starting materials through divergent, one‐pot cascade ring‐expansion reactions. Following either conjugate addition with an amine or nitromethane, or osmium(VIII)‐catalysed dihydoxylation, rearrangement through a four‐atom ring expansion takes place spontaneously to form the ring expanded products. A second ring expansion can also be performed following a second iteration of imide formation and alkene functionalisation/ring expansion. In the dihydroxylation series, three‐ or four‐atom ring expansion can be performed selectively, depending on whether the reaction is under kinetic or thermodynamic control. [ABSTRACT FROM AUTHOR]

Catalysts that distinguish between electronically distinct carbon-hydrogen (C–H) bonds without relying on steric effects or directing groups are challenging to design. In this work, cobalt precatalysts supported by N-alkyl-imidazole–substituted pyridine dicarbene (ACNC) pincer ligands are described that enable undirected, remote borylation of fluoroaromatics and expansion of scope to include electron-rich arenes, pyridines, and tri- and difluoromethoxylated arenes, thereby addressing one of the major limitations of first-row transition metal C–H functionalization catalysts. Mechanistic studies established a kinetic preference for C–H bond activation at the meta-position despite cobalt-aryl complexes resulting from ortho C–H activation being thermodynamically preferred. Switchable site selectivity in C–H borylation as a function of the boron reagent was thereby preliminarily demonstrated using a single precatalyst. [ABSTRACT FROM AUTHOR]

The in situ-generated N-aryl nitrile imines derived from trifluoroacetonitrile smoothly undergo (3+2)-cycloadditions onto the enone fragment of the levoglucosenone molecule, yielding the corresponding, five-membered cycloadducts. In contrast to the 'classic' C(Ph),N(Ph) nitrile imine, reactions with fluorinated C(CF3),N(Ar) analogues lead to stable pyrazolines in a chemo- and stereoselective manner. Based on the result of X-ray single crystal diffraction analysis, their structures were established as exo-cycloadducts with the location of the N-Ar terminus of the 1,3-dipole at the α-position of the enone moiety. The DFT computation demonstrated that the observed reaction pathway results from the strong dominance of kinetic control over thermodynamic control. [ABSTRACT FROM AUTHOR]

The occurrence of manganese (Mn) oxides on Mars is believed to be an indicator of an O 2 -rich paleoenvironment of Mars because Mn oxides often form through the oxidation of Mn(II) by O 2 on the surface of Earth. An alternative formation pathway was recently proposed, in which Mn(II) is oxidized by bromate (BrO 3 −), a common oxidant in contemporary Martian regolith. However, the oxidation of Mn(II) by bromate in solution is kinetically controlled and slow unless using very high concentrations (100 mM) of reactants that may be irrelevant to the conditions of Mars. We conducted laboratory simulations to determine whether iron (Fe) oxides (hematite and goethite) and a phyllosilicate (montmorillonite), abundant minerals on the surface of Mars, could catalyze the oxidation of Mn(II) by bromate. Hematite and goethite, but not montmorillonite, dramatically accelerated the oxidation with a low concentration (1 mM) of Mn(II) and bromate under various solution conditions. The reaction system was autocatalytic with Fe oxides initiating the oxidation of Mn(II) at the early stage and the subsequent catalysis mainly provided by the Mn oxide products. In contrast to producing Mn(IV)O 2 only during the homogeneous oxidation of Mn(II) by bromate in solutions, the heterogeneous mineral-surface catalyzed oxidation resulted in a mixture of Mn(III)OOH and Mn(IV)O 2 phases. Mn(III)OOH was an intermediate product and can be further oxidized by bromate to Mn(IV)O 2. The occurrence and accumulation of the intermediate product MnOOH can be attributed to its rapid formation due to surface-enhanced nucleation and growth on Fe oxide surfaces and to its higher resistance to oxidation by bromate than Mn(III) ions or clusters. Overall, mineral-surface catalyzed oxidation of Mn(II) by bromate is favorable from both thermodynamic and kinetic perspectives, and can be a major pathway for the occurrence of Mn oxides on Mars where microorganisms are lacking to catalyze the reaction. Our study further improves our understanding of the thermodynamic and kinetic controls on Mn(II) oxidation. [ABSTRACT FROM AUTHOR]

Axially chiral N‐substituted quinazolinones are important bioactive molecules, which are presented in many synthetic drugs. However, most strategies toward their atroposelective synthesis are mainly limited to the axially chiral arylquinazolinone frameworks. The development of modular synthetic methods to access diverse quinazolinone‐based atropisomers remains scarce and challenging. Herein, we report the regio‐ and atroposelective synthesis of axially chiral N‐vinylquinazolinones via the strategy of asymmetric allylic substitution‐isomerization. The catalysis system utilized both asymmetric transition‐metal catalysis and organocatalysis to efficiently afford trisubstituted and tetrasubstituted N‐vinylquinazolinone atropisomers, respectively. With the meticulous design of β‐substituted allylic substrates, both Z‐ and E‐tetrasubstituted axially chiral N‐vinylquinazolinones were obtained in good yields and high enantioselectivities. [ABSTRACT FROM AUTHOR]

Herein, we for the first time report a reversible conversion between green-emissive [DMPZ]MnCl4 and red-emissive [DMPZ]4(MnCl6)(MnCl4)2·(H2O)2 (DMPZ = 1,4-dimethylpiperazine) using kinetic and thermodynamic controlling strategies. Significantly, the synchronous structural and emission transformations in single-component organic manganese halides with adjustable emission colors are highlighted. [ABSTRACT FROM AUTHOR]

A bimetallic core–shell nanostructure is a versatile platform for achieving intriguing optical and catalytic properties. For a long time, this core–shell nanostructure has been limited to ones with noble metal cores. Otherwise, a galvanic replacement reaction easily occurs, leading to hollow nanostructures or completely disintegrated ones. In the past few years, great efforts have been devoted to preventing the galvanic replacement reaction, thus creating an unconventional class of core–shell nanostructures, each containing a less-stable-metal core and a noble metal shell. These new nanostructures have been demonstrated to show unique optical and catalytic properties. In this work, we first briefly summarize the strategies for synthesizing this type of unconventional core–shell nanostructures, such as the delicately designed thermodynamic control and kinetic control methods. Then, we discuss the effects of the core–shell nanostructure on the stabilization of the core nanocrystals and the emerging optical and catalytic properties. The use of the nanostructure for creating hollow/porous nanostructures is also discussed. At the end of this review, we discuss the remaining challenges associated with this unique core–shell nanostructure and provide our perspectives on the future development of the field. [ABSTRACT FROM AUTHOR]

Supramolecular copolymers have attracted much attention due to their potential functionalities. However, the co‐assembly strategies to construct co‐assemblies of small molecules with well‐defined sequence structures are still limited, especially for more complex crystalline block co‐assemblies. Herein, we target this challenge by designing IrIII complexes 1 and 2, which possess unique self‐assembly pathways and are capable of forming crystalline assemblies in aqueous systems. Specifically, block and random co‐assemblies of 1 and 2 can be synthesized by kinetic and thermodynamic control, respectively. Meanwhile, by adjusting the water content to orthogonalize the on‐pathway and the off‐pathway, an unprecedented pathway‐switching approach is realized to synthesize block and random co‐assemblies. By coupling the kinetic pathways, the present co‐assembly strategies are expected to pave the way for the synthesis of crystalline co‐assemblies of small molecules and the construction of organic heterostructures. [ABSTRACT FROM AUTHOR]

We show how to incorporate the possibility of kinetic control in the conceptual density functional theory formalism. This allow us to prove that the hard/soft acid/base principle will likely fail when the reactions are not thermodynamically-driven. [ABSTRACT FROM AUTHOR]

For the first time, the transformation of biobased 5-HMF derivatives succeeded in a 2 × [4 + 2] cascade cycloaddition reaction, leading to a drastic (3–5-fold) increase in molecular complexity as a result of one synthetic step. A new approach to the use of plant biomass in organic synthesis using a cascade Diels–Alder reaction of 5-HMF dimer derivatives with alkynes has been developed. This reaction proceeds under thermodynamic control, diastereoselectively and regioselectively, providing rapid access to compounds of high molecular complexity with the same synthetic availability as previously obtained regular cycloadducts. As a concept illustration, under conditions of kinetic control, cycloadditions of two molecules of dienophiles are realized, and the resulting products, when heated, rearrange into thermodynamically more favorable cascade products. Reaction pathways were studied in detail using quantum chemical calculations to reveal major factors influencing the selectivity of the process. Discovery of a new sustainability pathway should be noted – to date, oligomeric derivatives are considered a waste of 5-HMF degradation, while the present study highlights them as a valuable material for the synthesis of nonplanar scaffolds. [ABSTRACT FROM AUTHOR]

Cobalt ferrites exhibit widely varied magnetic behaviour due to the presence of a miscibility gap leading to the formation of periodic self-assembled nanostructures via spinodal decomposition. Periodicity and amplitude of the compositional fluctuations can be controlled by thermodynamic and kinetic processing parameters which allows for careful tuning of the magnetic properties. Although reports have shown evidence of spinodal decomposition, there is a lack of detailed characterization of the magnetic interactions and reversal mechanisms in these materials. In this work we use high-resolution first order reversal curves (FORC) measurements to understand the underlying magnetic processes occurring in a cobalt ferrite with a nominal composition of Co1.8Fe1.2O4 before (calcined) and after spinodal decomposition (annealed). Additionally, FORC measurements with preconditioning fields were conducted to separate the interaction signatures at low coercive fields by biasing the sample in positive and negative mean fields. Microstructural characterization using TEM combined with EDS showed uniform chemistry in the calcined sample and the presence of Fe rich and Co rich regions in the annealed sample, due to spinodal decomposition. Signs of positive exchange interactions were observed in both calcined and annealed samples. This work presents the first detailed magnetic characterization of magnetic interactions in a nanostructured cobalt ferrite, and provides an example of magnetic characterization of nanostructured ferrites using FORC. [ABSTRACT FROM AUTHOR]

Epoxy (EP) was copolymerized with polyamic acid (PAA, precursor of polyimide (PI)) with termanil monomers of (1) 4,4′-Oxydianiline (ODA) and (2) pyromellitic dianhydride (PMDA) individually to form (PI-O-EP) and (PI-P-EP) copolymers. The FTIR spectrum of PI-O-EP copolymerization intermediates shows that some amide-EP linkages were formed at low temperature and were broken at higher temperature; in additoin, the released amide was available for subsequent imidization to form PI. The curing and imidization of the amide groups on PAA were determined by reaction temperature (kinetic vs. thermodynamic control). In PI-P-EP, the released amide group was very short-lived (fast imidization) and was not observed on FTIR spectra. Formation and breakage of the amide-EP linkages is the key step for EP homopolymerization and formation of the interpenetration network. PI contributed in improving thermal durability and mechanical strength without compromising EP's adhesion strength. Microphase separations were minimal at PI content less than 10 wt%. The copolymerization reaction in this study followed the "kinetic vs. thermodynamic control" principle. The copolymer has high potential for application in the field of higher-temperature anticorrosion. [ABSTRACT FROM AUTHOR]

In this review, we aim to present new concepts for the revisited separation of enantiomers from racemic compounds and a protocol worth to be followed in designing the preparation of pure enantiomers. We have taken into account not only the influence of the properties (eutectic composition) and characteristics of the reactants (racemic compound, resolving agent), but also the behavior of the resulting diastereomers and the different conditions (e.g., crystallization time, solvents used, solvate-forming compounds, achiral additives, etc.). The examples discussed are resolutions developed by our research team, through which we will try to illustrate the impact of all these considerations, presenting the methodological investigations interpreting recent discoveries and observations. Some special solid-state analytical and structural investigations assisting us in the elucidation and invention design of the resolution processes of some active pharmaceutical ingredients, such as Tetramisole, tofisopam, and Amlodipine, are also shown. [ABSTRACT FROM AUTHOR]

The treatment of cis-[PtCl2(XylNC)2] with thiazol-2-amines in a 2:1 ratio leads to a regioisomeric mixture of two binuclear complexes. These regioisomers are products of kinetic and thermodynamic control capable of regioisomerization. When the same reaction is carried out with a 5-fold excess of thiazol-2-amine, the nucleophile is able to react with the in situ-formed binuclear platinum(II) complexes, yielding a new type of bis-carbene platinum species. All new isolated compounds were characterized by 1H, 13C{1H}, and 195Pt{1H} NMR spectroscopy, high-resolution ESI-MS, and single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

Elaboration of a convenient route towards donor-substituted pyrazoles from heteropropargyl precursors is challenging due to a number of thermodynamically favorable side reactions (e.g., acetylene–allene isomerization and Glaser homocoupling). In this work, Sonogashira cross-coupling conditions of 4-tert-butylphenyl propargyl ether with benzoyl chloride followed by tandem Michael addition/cyclocondensation with hydrazine into 3,5-disubstituted pyrazole (kinetic control), as well as cycloisomerization conditions of ketoacetylene intermediate into 2,5-disubstituted furan (thermodynamic control), were established through a variation of the catalyst loading, solvent polarity, excess of triethylamine, and time of reaction. During the optimization of process parameters, a number of by-products represented by a monophosphine binuclear complex (PPh3PdI2)2 with two bridging iodine atoms and diyne were identified and isolated in the pure form. The quantum-chemical calculations and solution-state 1H/13C NMR spectroscopy suggested that the 5(3)-(4-tert-butylphenyloxy)methoxy-3(5)-phenyl-1H-pyrazole exists in the tautomeric equilibrium in a polar methanol solvent and that individual tautomers could be characterized in case aprotic solvents employed. The pyrazole features a unique tetramer motif in the crystal phase formed by alternating 3(5)-phenyl-1H-pyrazole tautomers, which was stabilized by N–H···N bonds and stacking interactions of pyrazole rings, whereas pyrazole dimers were identified in the gas phase. [ABSTRACT FROM AUTHOR]

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We report on the insertion of alkynes into heterometallic M–M′ bonds, producing (aluminylalkenyl)copper compounds which possess differential reactivity at the two derived M–C functions. Uniquely, this system is capable of controlling access to isolable syn or anti dimetallated alkenes, by employing either kinetic or thermodynamic control. Subsequent derivatization with CO is both stereoselective (to syn systems) and regioselective (to Cu–C bonds), leading to the formation of the first structurally characterized examples of copper acyl compounds - aided by the cooperative reactivity of the proximal aluminium centre. [ABSTRACT FROM AUTHOR]

A logical construction of monomeric subunits armed with the carbonyl functionality allowing post-synthetic reactivity leads to the convergent formation of π-extended defected units activated with BBr3. The kinetic or thermodynamic control entraps either the pyrido[2,3-g]quinoline or the 4,7-phenanthroline motifs doped with boron(III), which deeply modulates the optical properties. [ABSTRACT FROM AUTHOR]

Lead halide perovskites with fascinating optoelectronic properties have enabled rapid advancement and development in photovoltaics and light-emitting diodes. However, accessing and stabilizing the complex ternary phase space diagram (Cs-Pb-Br) of perovskites including 3 D nanocrystals, 2 D nanoplatelets, and 0 D hexagonal platelets with desirable optoelectronic properties further requires a deeper understanding of the thermodynamic and kinetic aspects regarding the growth of lead halide perovskite nanocrystals. In this work, we have mapped out the multivariant synthetic design spaces observed in the ternary phase diagram of Cs-Pb-Br to evaluate the effect of controlling thermodynamic equilibrium state (e.g. chemical potentials of the Cs:Pb ratio) and growth kinetics with ligand concentration (oleylamine). Further in-situ tracking of reversible phase transformation with the addition of oleylamine (forward) and PbBr2 (reverse) exhibiting distinctive spectroscopic signatures between 3 D and 0 D phases (vice versa) can provide insight into the reversible phase transformation mechanism and important role of PbBr2 species that can modify the bonding motif and connectivity of [PbBr6]4- octahedral frameworks. [ABSTRACT FROM AUTHOR]

If various compounds exist in the system "metal cation–C6N7O33−–H2O" (where C6N7O33− is cyamelurate anion), the synthesis temperature can affect the isolation of a particular product. Short reaction times together with low temperatures favor the release of kinetic products, and an increase in temperature, on the contrary, can lead to the formation ofthermodynamic ones. It is found that several structural types exist in the row of rare earth cyamelurates. Room temperature synthesis leads to the formation of [Ln(H2O)7C6N7O3] (Ln = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er); an increase in temperature yields thermodynamically more stable [Ln(H2O)4C6N7O3]n·nH2O (Ln = Y, Ho, Er, Tm, Yb, Lu) and [Ln(H2O)5C6N7O3]n (Ln = Pr, Nd). The change in the synthesis temperature did not affect the structures of Sm, Eu, Gd, Tb, and Dy cyamelurates, as well as the structure of lanthanum cyamelurate [La(H2O)6C6N7O3]·H2O. In [Ln(H2O)4C6N7O3]n·nH2O and [Ln(H2O)5C6N7O3]n synthesized at increased temperature, cyamelurate anion acts as a bridging ligand, leading to polymeric chains. Kinetically trapped Y, Pr, Nd, Ho, and Er cyamelurates, in contrast, consist of individual complex molecules [Ln(H2O)7C6N7O3]. Probably, steric difficulties caused a decrease in the coordination number of Y, Ho, and Er from 9 to 8 in the thermodynamic product. The coordination number of Pr and Nd remains equal to 9 in both types of compounds. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chronoamperometric measurements provide reliable values for apparent activation energies. • Methanol oxidation pathways yielding reaction byproducts predominate at lower temperatures. • The oxidation pathway via CO ad becomes dominant at temperatures exceeding 30 °C. • Adequate mass transport conditions are essential for the complete conversion of methanol to CO 2. Methanol is one of the key molecules in the challenge towards a sustainable future, particularly as a renewable hydrogen carrier fuel and as a low-carbon and net carbon-neutral liquid chemical. For most applications, it is imperative to understand the impact of temperature on the methanol electro-oxidation reaction (MEOR). In this study, the influence of the temperature on the kinetics of the MEOR and the parallel reaction pathways is assessed by investigating responses in both conventional and oscillatory regimes using a single-crystal Pt(1 0 0) electrode. Our findings demonstrate that chronoamperometric measurements under steady-state conditions provide more reliable values for apparent activation energies compared to transient conditions. Furthermore, a temperature-dependent shift in the dominance of specific oxidation pathways is observed, analogous to a kinetic and thermodynamic control mechanism, preventing the complete poisoning of the electrode surface. Specifically, oxidation pathways leading to the formation of reaction byproducts predominate at lower temperatures, while the oxidation pathway via CO ad becomes dominant at temperatures exceeding 30 °C. Moreover, our research shows that, at shorter times, temperature changes minimally affect the mean potential required to sustain the applied current during the oscillations in a galvanostatic experiment, which is closely linked with the voltaic efficiency. However, over longer periods, when mass transport phenomena become significant and mixed-mode oscillations occur, elevated temperatures increase the mean potential, resulting in reduced voltaic efficiency. Therefore, to facilitate the complete conversion of methanol to CO 2 without increasing the mean potential for current maintenance, it is essential not only to increase the temperature but also to improve the mass transport conditions to mitigate the mixed-mode oscillations, despite their lower minima reached during oscillation. This idea challenges the conventional assumption that a lower minimum potential implies a lower mean potential during oscillations. This advancement propels our understanding to a more sophisticated level, providing valuable insights to guide the materials design to increase the conversion efficiency and optimize the operating temperature of devices crucial to energy conversion. [ABSTRACT FROM AUTHOR]

Tetraphenylethylene-functionalized amphiphilic Janus dendrimers of up to third generation are synthesized. Their self-assembly has been studied under kinetic and thermodynamic control. By varying the dendrimer generation number and the self-assembly condition, fluorescent dendrimersomes of tunable size (∼60–200 nm) and quantum yield (5.7–17.4%) are obtained in aqueous medium. [ABSTRACT FROM AUTHOR]

Associations of amphiphiles assume their various morphologies according to the so‐called packing parameter under thermodynamic control. However, one may raise the question of whether polymers can always relax fast enough to obey thermodynamic control, and how this may be checked. Here, a case of polyion complex (PIC) assemblies where the morphology appears to be subject to kinetic control is discussed. Poly (ethylene oxide)‐b‐(styrene sulfonate) block copolymers are combined with cationic PAMAM dendrimers of various generations (2–7). The PEO‐PSS diblocks, and the corresponding PSS‐PEO‐PSS triblocks should have nearly identical packing parameters, but surprisingly creat different assemblies, namely core‐shell micelles and vesicles, respectively. Moreover, the micelles are very stable against added salt, whereas the vesicles are not only much more sensitive to added salt, but also appear to exchange matter on relevant time scales. The small and largely quenched early‐stage precursor complexes are responsible for the morphological and dynamic differences, implying that kinetic control may also be a way to obtain particles with well‐defined and useful properties. The exciting new finding that triblocks produce more "active" vesicles will hopefully trigger the exploration of more pathways, and so learn how to tune PICsomes toward specific applications. [ABSTRACT FROM AUTHOR]

The number and type of new supramolecular polymer (SMP) systems have increased rapidly in recent years. Some of the key challenges faced for these novel systems include gaining full control over the mode of self‐assembly, the creation of novel architectures and exploring functionality. Here, we provide a critical overview of approaches related to perylene‐based SMPs and discuss progress to exert control over these potentially important SMPs through chemical modification of the imide substituents. Imide substitutions affect self‐assembly behaviour orthogonally to the intrinsic optoelectronic properties of the perylene core, making for a valuable approach to tune SMP properties. Several recent approaches are therefore highlighted, with a focus on controlling 1) morphology, 2) H‐ or J‐ aggregation, and 3) mechanism of growth and degree of aggregation using thermodynamic and kinetic control. Areas of potential future exploration and application of these functional SMPs are also explored. [ABSTRACT FROM AUTHOR]

The fabrication of room‐temperature organic phosphorescence and afterglow materials, as well as the transformation of their photophysical properties, has emerged as an important topic in the research field of luminescent materials. Here, we report the establishment of energy landscapes in dopant‐matrix organic afterglow systems where the aggregation states of luminescent dopants can be controlled by doping concentrations in the matrices and the methods of preparing the materials. Through manipulation by thermodynamic and kinetic control, dopant‐matrix afterglow materials with different aggregation states and diverse afterglow properties can be obtained. The conversion from metastable aggregation state to thermodynamic stable aggregation state of the dopant‐matrix afterglow materials to leads to the emergence of intriguing afterglow transformation behavior triggered by thermal and solvent annealing. The thermodynamically unfavorable reversible afterglow transformation process can also be achieved by coupling the dopant‐matrix afterglow system to mechanical forces. [ABSTRACT FROM AUTHOR]

The possible evolutionary significance of pyrophosphate (PPi) has been discussed since the early 1960s. Lipmann suggested that PPi could have been an ancient currency or a possible environmental source of metabolic energy at origins, while Kornberg proposed that PPi vectorializes metabolism because ubiquitous pyrophosphatases render PPi forming reactions kinetically irreversible. To test those ideas, we investigated the reactions that consume phosphoanhydride bonds among the 402 reactions of the universal biosynthetic core that generates amino acids, nucleotides, and cofactors from H2, CO2, and NH3. We find that 36% of the core's phosphoanhydride hydrolyzing reactions generate PPi, while no reactions use PPi as an energy currency. The polymerization reactions that generate ~80% of cell mass – protein, RNA, and DNA synthesis – all generate PPi, while none use PPi as an energy source. In typical prokaryotic cells, aminoacyl tRNA synthetases (AARS) underlie ~80% of PPi production. We show that the irreversibility of the AARS reaction is a kinetic, not a thermodynamic effect. The data indicate that PPi is not an ancient energy currency and probably never was. Instead, PPi hydrolysis is an ancient mechanism that imparts irreversibility, as Kornberg suggested, functioning like a ratchet's pawl to vectorialize the life process toward growth. The two anhydride bonds in nucleoside triphosphates offer ATP-cleaving enzymes an option to impart either thermodynamic control (Pi formation) or kinetic control (PPi formation) upon reactions. This dual capacity explains why nature chose the triphosphate moiety of ATP as biochemistry's universal energy currency. [ABSTRACT FROM AUTHOR]

The kinetic control of chemical reactions makes it possible both to isolate metastable substances with properties different from those of thermodynamically stable phases and to obtain information useful for studying the crystal nucleation and further transformations of metastable phases into stable ones. Metal cyamelurates are suitable subjects for kinetic control in synthesis due to their easy crystallization and short reaction times. In this work, cobalt, manganese, magnesium, copper, aluminum, chromium, calcium, and lead cyamelurates were obtained and their crystal structures were determined. Most syntheses at room temperature take place under kinetic control, and this often leads to a mixture of phases. KM(C6N7O3)·5H2O (M = Co(II), Mn(II)) powders consisted of one crystalline compound. An increase in temperature leads to thermodynamic control, which is proved by registration of Mn(C6N7O3H)·5H2O and KMg(C6N7O3)·5H2O crystalline phases. It was possible to isolate Ca(C6N7O3H)·6H2O and Pb(C6N7O3H)·3H2O from the mixture by washing samples with a weak acid solution. As a result of the work, five different structural types were obtained, including KCu(C6N7O3)∙2H2O and KM(C6N7O3H)2·6H2O (M = Al, Cr(III)). Despite the diversity of salts obtained as a result of thermodynamic or kinetic control, practically the same building blocks form the crystal structure of cyamelurates. The hypothesis of nucleation in a colloidal micelle with electric double layer can be applied to the compounds listed above. [ABSTRACT FROM AUTHOR]

Photocatalysis offers a practical solution to the ever increasing energy and environmental issues by using a semiconductor to harvest freely available sunlight. Photoactive organic semiconductor nanocrystals (OSNs) are promising photocatalysts due to their structure and function which are easily tunable by molecular design. Extensive studies have yielded significant progress on OSNs in terms of photoresponse, charge carrier mobility, as well as photoconversion efficiency. This review provides a comprehensive discussion of the emerging crystal and interface engineering strategies used in optimizing structure/property of OSNs. The basic mechanisms involved in organic photocatalysis are discussed, for a better understanding of its dependence on the molecular and supramolecular structures. Then, the intermolecular interactions in molecular packing and the kinetic and thermodynamic control over the crystal growth process are summarized, with the aim of tuning the optical and electrical properties. Band energy alignment, charge carrier dynamics, and charge transfer are discussed in different heterostructures. In each case, structure/property relationships and how to tune them are emphasized. Finally, challenges and opportunities for the practical use of the organic photocatalysts are discussed. [ABSTRACT FROM AUTHOR]

This article reveals 4‐dimethylaminopyridine (DMAP) regulated pathway selectivity in the supramolecular polymerization of a naphthalene‐diimide derivative (NDI‐1), appended with a carboxylic acid group. In decane, NDI‐1 produces ill‐defined aggregate (Agg‐1) due to different H‐bonding motifs of the −COOH group. With one mole equivalent DMAP, the NDI‐1/DMAP complex introduces new nucleation condition and exhibits a cooperative supramolecular polymerization producing J‐aggregated fibrillar nanostructure (Agg‐2). With 10 % DMAP and fast cooling (10 K/min), similar nucleation and open chain H‐bonding with the free monomer in an anti‐parallel arrangement produces identical J‐aggregate (Agg‐2a). With 2.5 % DMAP and slow cooling (1 K/min), a distinct nucleation and supramolecular polymerization pathway emerge leading to the thermodynamically controlled Agg‐3 with face‐to‐face stacking and 2D‐morphology. Slow cooling with 5–10 % DMAP produces a mixture of Agg‐2a and Agg‐3. Computational modelling studies provide valuable insights into the internal order and the pathway complexity. [ABSTRACT FROM AUTHOR]

The intramolecular oxidative coupling of electron-rich aromatic groups in 5-(het)aryl-1-(het)arylalkyl-1H-1,2,3-triazoles was studied in detail. Under treatment with phenyliodoso bis(trifluoroacetate) and boron trifluoride etherate these substrates afforded products of either ortho/ortho or ortho/ipso coupling depending on the nature of aromatic groups and reaction conditions applied. It was found that for substrates which are capable for both types of coupling, ortho-/ipso-adducts are formed under kinetic control while ortho-/ortho-products are formed under thermodynamic control. The developed procedures allow preparation of complex polycyclic azaheterocycles from simple precursors in two steps only. [ABSTRACT FROM AUTHOR]

Selective synthetic modifications on diamondoids (well‐defined molecular nano‐diamonds) are difficult. Group IV organometallic complexes are promising systems for CH bond activation. We study the CH bond activation of the hard‐to‐activate CH2 positions of the adamantyl group (the smallest diamondoid) using density functional theory. As a platform for activation, we tether the adamantyl group to the cyclopentadienyl in a substituted bis‐cyclopentadienyl group IV metal diphenyl complex. The mechanism proposed in the experimental paper reporting the activation of C(Me)2‐Ph or t‐Bu groups using Zr(IV) involves an η2‐benzyne complex intermediate. Our computational work confirms the two‐step mechanism proposed for activation of C(Me)2‐Ph or t‐Bu using Zr(IV) and further extends it to Ti(IV) and Hf(IV). The first step forms the benzyne complex. In the second step, the cyclopentadienyl‐bound group is activated through a mechanism that closely resembles a σ‐bond metathesis when the benzyne complex is described as a metallacyclopropene We demonstrate through computations that the two‐step reaction can be successfully applied to the adamantyl group. CH bond activation of adamantyl is found to be thermodynamically and kinetically feasible. The important question of regioselectivity is addressed. We predict that α‐CH bond activation will be achievable with Ti (thermodynamic control), and selective γ‐CH bond activation with Zr (kinetic or thermodynamic control). [ABSTRACT FROM AUTHOR]

SDS was found to effectively promote the Mannich reaction of different aniline, aldehydes and 2-butanone to afford the Mannich reaction with excellent regioselectivity in major product and highly anti -diastereoselectivity in minor by-product, conditions successfully employed as a key reaction for the stereoselective synthesis. [Display omitted] • SDS was found to effectively promote the Mannich reaction. • Excellent regioselectivity in major product. • Highly anti -diastereoselectivity in minor by-product. • Conditions successfully employed as a key reaction for the stereoselective synthesis. Regioselective and diastereoselective synthesis of β-aminocarbonyl compounds is examined in the presence/ absence of sodium dodecyl sulfate (SDS) as surfactant. Mannich reaction between derivatives of aniline, benzaldehyde and 2-butanone is performed in different conditions. The optimum condition are acquired include 1 mol % SDS per reactants in aqueous solvent at room temperature. Finding show conditions successfully employed to achieve remarkable kinetic control for the regioselective less-substituted Mannich product. In the absence of surfactant, other regioisomer; the more-substituted Mannich products (thermodynamic control) are obtained in slightly too moderate syn -diastereoselectivity depending on the substituent type on aniline. Although kinetic control produces less-substituted regioisomer but diasteroselectivity of the minor product is highly preferred anti- isomer which affected in the presence of surfactant. [ABSTRACT FROM AUTHOR]

• The two diepoxide-α-himachalenes 6 and 7 , exhibit regio- and stereospecificity in their opening epoxidation reaction. • The best interaction was predicted by the Parr functions and the energy study to be between the C13 carbon and the hydride. • Via kinetic and thermodynamic control, alcohol 8 is synthesized. • Alcohol (9) and β -himachalene (1) have greater affinities for the coronavirus and HIV-1, respectively. The ring-opening reaction of the two diepoxides, α-himachalenes 6 and 7 , with aluminum lithium hydride (LiAlH 4) in ether produced the title compounds C 15 H 24 O 2 sesquiterpene alcohol. Both experimentally and conceptually, the regio- and stereospecificity of this ring opening reaction were investigated using the Molecular Electron Density Theory (MEDT). The Parr functions and the energy study correctly predicted the best interaction to be between the C13 carbon and the hydride, as evidenced by the attained regio- and stereo-specificity revealed through the experimental research. Moreover, the alcohol 8 is obtained from a kinetic and thermodynamic control while the alcohol 9 is obtained only by a kinetic control, in the maximum conformity with the findings of the experiments. In addition, the performed docking calculations to examine the coronavirus and HIV-1 activities of the products 1 – 9 revealed that alcohol 9 has a higher affinity against coronavirus while β-himachalene 1 against the HIV-1. [ABSTRACT FROM AUTHOR]

One-dimensional zinc oxide arrays with various finely controlled microscopic morphologies are grown on fluorine-doped tin oxide substrates by a hydrothermal method. The relationship between the microscopic morphologies and the reaction conditions are studied deeply. It is found that although all the studied reaction parameters, like reaction time, pH value, concentration of the reactants and so on, can affect the microstructures of the resultant products, what they affect, in essence, is the concentration of free Zn2+ ions of the solution. By exploring the evolution of the microstructure of the one-dimensional zinc oxide crystals, it is proved that the formation of the various microscopic morphologies is a result of the competition between the kinetic control and the thermodynamic control during the crystal growth, which in turn is mainly determined by the concentration of the free Zn2+ ions in the solution. The in-depth exploration of the growth mechanism of zinc oxide and the fine control of its microscopic morphologies is expected to provide advanced materials for current and future cutting-edge applications of zinc oxide. It is also expected that the growth mechanism reported here can provide theoretical support for achieving other oxide materials whose microstructure can be finely controlled. [ABSTRACT FROM AUTHOR]

In quantum chemical calculations, the Diels–Alder (DA) cycloaddition reaction of furan with maleic anhydride favors the endo‐isomer kinetically in the gas phase. This preference, however, changes in favor of the exo‐isomer on inclusion of solvent effects. For example, in acetonitrile, the exo‐isomer was calculated to form twice as fast as the endo‐isomer at room temperature, an observation that corroborates well with the experiments. The free energy change of the reaction is such that it allows faster reversal of the endo‐isomer to the reactants in an equilibrium process and, thus, the predominance of the more stable exo‐isomer eventually. The reaction of furan with maleimide is similar to that with maleic anhydride. However, it predominantly favors endo‐selectivity at temperatures below 320 K, which is also in excellent agreement with the experimental studies of temperature dependence of this DA reaction. Further, a gedanken calculation of the DA reaction of furan with cyclopropene has been investigated to delineate the effect of the retro‐pathway on stereoselectivity. [ABSTRACT FROM AUTHOR]

Thermodynamic and kinetic control of a chemical process is the key to access desired products and states. Changes are made when a desired product is not accessible; one may manipulate the reaction with additional reagents, catalysts and/or protecting groups. Here we report the use of carbon dioxide to accelerate cyanohydrin synthesis under neutral conditions with an insoluble cyanide source (KCN) without generating toxic HCN. Under inert atmosphere, the reaction is essentially not operative due to the unfavored equilibrium. The utility of CO2‐mediated selective cyanohydrin synthesis was further showcased by broadening Kiliani–Fischer synthesis under neutral conditions. This protocol offers an easy access to a variety of polyols, cyanohydrins, linear alkylnitriles, by simply starting from alkyl‐ and arylaldehydes, KCN and an atmospheric pressure of CO2. [ABSTRACT FROM AUTHOR]

Mono‐ and bis‐decylated lumazines have been synthesized and characterized. Namely, mono‐decyl chain [1‐decylpteridine‐2,4(1,3H)‐dione] 6a and bis‐decyl chain [1,3‐didecylpteridine‐2,4(1,3H)‐dione] 7a conjugates were synthesized by nucleophilic substitution (SN2) reactions of lumazine with 1‐iododecane in N,N‐dimethylformamide (DMF) solvent. Decyl chain coupling occurred at the N1 site and then the N3 site in a sequential manner, without DMF condensation. Molecular orbital (MO) calculations show a p‐orbital at N1 but not N3, which along with a nucleophilicity parameter (N) analysis predict alkylation at N1 in lumazine. Only after the alkylation at N1 in 6a, does a p‐orbital on N3 emerge thereby reacting with a second equivalent of 1‐iododecane to reach the dialkylated product 7a. Data from NMR (1H, 13C, HSQC, HMBC), HPLC, TLC, UV‐vis, fluorescence and density functional theory (DFT) provide evidence for the existence of mono‐decyl chain 6a and bis‐decyl chain 7a. These results differ to pterin O‐alkylations (kinetic control), where N‐alkylation of lumazine is preferred and then to dialkylation (thermodynamic control), with an avoidance of DMF solvent condensation. These findings add to the list of alkylation strategies for increasing sensitizer lipophilicity for use in photodynamic therapy. [ABSTRACT FROM AUTHOR]

Di‐2,7‐naphthihexaphyrin(1.1.1.1.1.1), a non‐aromatic carba‐analogue of the hexaphyrin(1.1.1.1.1.1), incorporating two built‐in 2,7‐naphthylene moieties was synthesized as two separate, conformationally locked stereoisomers. Both conformers followed complex protonation pathways involving structurally different species, which can be targeted under kinetic and thermodynamic control. The neutralization of the ultimate dicationic product, accessible from both stereoisomers of the free base, allowed to realize the complex conformational switching cycle involving six structurally different species. [ABSTRACT FROM AUTHOR]

A retrospective review of reversibility revealed in Friedel–Crafts acyl rearrangements of polycyclic aromatic ketones derived from the polycyclic aromatic hydrocarbons naphthalene, phenanthrene, anthracene, fluorene, pyrene, and fluoranthene is presented. The reactions were carried out in polyphosphoric acid (PPA). A distinction is made between completely reversible reaction (equilibrium reaction) denoted by ⇌ and reaction, both directions denoted by ⇆. Reaction, both direction is considered reversible reaction, not completely reversible reaction. Gore's 1955 proposition that Friedel–Craft acylation of reactive hydrocarbons is a reversible process has been verified. Complete reversibility has been revealed in ortho⇌para acyl rearrangements of fluorofluorenones (1FFL ⇌ 3FFL) and in dibenzofluorenones (DBahFL ⇌ DBbhFL). Both cases are intramolecular acyl rearrangements. The majority of reversible intramolecular and intermolecular Friedel–Crafts acyl rearrangements are formally "reaction, both directions," e.g., dibenzoylpyrenes 1,6-Bz2PY ⇆ 1,8-Bz2PY. Acyl rearrangements and reversibility in Friedel–Crafts acylations are associated with thermodynamic control. However, sometimes kinetic control wins out over thermodynamic control. Polycyclic aromatic ketones in which the carbonyl group is coplanar with the aromatic nucleus may undergo Friedel–Crafts acyl rearrangements. The reversibility concept has been applied to the synthesis of new and known linearly annelated polycyclic aromatic ketones by intramolecular Friedel–Crafts rearrangements of their angularly annelated constitutional isomers. A linkage between reversible Friedel–Crafts acyl rearrangements in PPA and the Scholl reaction has been established in benzoylnaphthalenes and in dibenzoylpyrenes. As a structural chemistry practitioner, the scientific personality of the first author belongs to the foxes, rather than to the hedgehogs. [ABSTRACT FROM AUTHOR]

The discovery of safe, general, and practical procedures to prepare vinyl fluorides from readily available precursors remains a synthetic challenge. The metal‐free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Introduced here is an inexpensive and easily handled reagent that enables the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These reaction conditions were suitable for a diverse collection of alkynes, including several highly functionalized pharmaceutical derivatives. Computational and experimental mechanistic studies support C−F bond formation through vinyl cation intermediates, with the E‐ and Z‐hydrofluorination products forming under kinetic and thermodynamic control, respectively. [ABSTRACT FROM AUTHOR]

Morphology control in multiblend all‐polymer solar cells is crucial for improving charge generation processes. Herein, it is demonstrated that the film morphology of the light‐harvesting layer of all‐polymer solar cells can be manipulated by incorporating a copolymer as the compatibilizer. Through in situ grazing‐incidence wide‐angle X‐ray scattering characterization, the insights of the crystallization kinetics of the polymer blends from solution to thin‐film state are provided. Of particular importance is that by kinetic and thermodynamic control of the film‐processing conditions, an optimal morphology with appropriate nanoscale fibrillar structure in a well‐mixed matrix is achieved. These findings indicate that the interplay between the crystalline regions and weakly/noncrystalline regions that are induced by the compatibilizer polymer plays a critical role in determining the morphology in multicomponent blend all‐polymer solar cells. [ABSTRACT FROM AUTHOR]

Supramolecular polymers, albeit having precise internal order, largely lack precision in the mesoscopic scale because in most examples supramolecular polymerization occurs under thermodynamic control through spontaneous self-assembly. Recent reports have exemplified that by varying experimental parameters including cooling rate, solvent composition, interplay of intra- vs. inter-molecular H-bonding and others, it is possible to retard the spontaneous nucleation, and isolate a dormant kinetically controlled monomeric/aggregated state which in turn can serve as the monomer pool to undergo controlled supramolecular polymerization (CSP) through a chain-growth mechanism in the presence of an aggregated/molecular initiator (seed) or by an external stimuli like light. Supramolecular polymers with narrow dispersity, predictable length or stereo-selectivity have been achieved by CSP. Chain extension (similar to "living" polymerization) in such seed initiated CSP is now possible by batch wise addition of monomers, allowing synthesis of supramolecular block copolymers. This feature article describes recent developments in CSP (primarily under kinetic control) of various π-conjugated building blocks. [ABSTRACT FROM AUTHOR]

Ring/chain competition in oligomerization reactions represents a long‐standing topic of synthetic chemistry and was treated extensively for solution reactions but is not well‐understood for the two‐dimensional confinement of surface reactions. Here, the kinetic and thermodynamic principles of ring/chain competition in on‐surface synthesis are addressed by scanning tunneling microscopy, X‐ray photoelectron spectroscopy, and Monte Carlo simulations applied to azulene‐based organometallic oligomers on Cu(111). Analysis of experiments and simulations reveals how the ring/chain ratio can be controlled through variation of coverage and temperature. At room temperature, non‐equilibrium conditions prevail and kinetic control leads to preferential formation of the entropically favored chains. In contrast, high‐temperature equilibrium conditions are associated with thermodynamic control, resulting in increased yields of the energetically favored rings. The optimum conditions for ring formation include the lowest possible temperature within the regime of thermodynamic control and a low coverage. The general implications are discussed and compared to the solution case. [ABSTRACT FROM AUTHOR]

Colloidal anisotropic gold nanocrystals play a central role in the field of plasmonics owing to their tunable optical activity across a wide spectral range. However, achieving sufficient optical quality for practical implementation requires advanced synthetic protocols yielding gold nanocrystals with the desired morphology and plasmonic properties. This Minireview focuses on a fundamental step during the growth of anisotropic nanocrystals, namely symmetry breaking. In connection with thermodynamic and kinetic control of nanocrystal growth, we discuss the complex interplay between the role of seed morphology and that of surfactants, shape‐directing additives and reducing agents. We revisit some iconic syntheses of anisotropic gold nanoparticles, including nanorods, nanotriangles, and nanobipyramids. Finally, we analyze the use of co‐surfactants as an emerging strategy to disconnect the symmetry breaking event from the anisotropic growth process, overcoming current limitations in the synthesis of anisotropic gold nanocrystals. [ABSTRACT FROM AUTHOR]