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This study developed three microstructured chitosan nanocapsules with immobilized lipase to explore chitosan-lipase interactions at different pH levels. Chitosan undergoes complete protonation or deprotonation based on pH level. Three distinct pH levels were examined: 5.5, where chitosan is fully protonated; 6.5, where chitosan is partially protonated/deprotonated; and 7.5, where chitosan is fully deprotonated. The nanocapsules exhibited nanoscale dimensions and the microstructures showed porous morphology. Immobilized lipase showed improved temperature stability, compared to free enzyme, especially in lipase supports at pH 5.5 and 7.5 due to electrostatic and hydrophobic interactions. The interactions between chitosan and lipase influenced the microenvironment around the active site, resulting in an optimum pH of 8 for all supports. Immobilized lipase at pH 5.5 and 7.5 displayed the best reusability in the hydrolysis of p-nitrophenyl palmitate under reaction conditions of 37 °C and pH 8. During refrigeration storage, all immobilized lipases maintained total activity for 7 days, but lipase immobilized at pH 6.5 maintained more the activity after 28 days. Therefore, this study has developed promising immobilized lipase, standing out not only for industrial application concerning cost-effectiveness, but also for the innovation in investigating the influence of chitosan-lipase interactions during immobilization. [ABSTRACT FROM AUTHOR]

The imaging reactions of resist materials used for nano-patterning have become radiation-chemical reactions, with the shortening of wavelengths of the exposure light sources in lithography systems. The most widely used patterning materials in industrial lithography are chemically amplified resists (CAR). Understanding the deprotonation mechanism of ionized polymers (radical cations) is important for acid generation in CARs. In this study, the dynamics of radical cations in poly(4-hydroxystyrene) (PHS)–type resist polymers, partially and totally protected by tert-butoxycarbonyl (t-BOC) groups, are investigated using a combination of electron pulse radiolysis experiments, acid yield measurements, and quantum chemical calculations. The t-BOC(oxy) group exhibits π-electron-donating behavior in the monomer cation but changes to electron-accepting behavior in the polymer cation, owing to the interaction between substituents. The destabilization of radical cations due to decreased intramolecular charge resonance may contribute to the high deprotonation efficiency of t-BOC-capped PHS polymers. [ABSTRACT FROM AUTHOR]

The improvement of photovoltaic and stability performance of tin (Sn)‐based halide perovskite solar cells is impeded by notorious oxidation issues and Anderson localization. Despite previous implements in antioxidation through the incorporation of Lewis base additives, there still exist ongoing uncertainties surrounding its complex interaction mechanisms. A perplexing phenomenon regarding accelerated oxidation in acrylic acid is discovered that deviates from conventional Lewis base–acid reaction. The underlying insights into the deprotonation of acrylic acid followed by the formation of a "tripod" ionic bonding form are provided, which results in amplifying the delocalization effect of electrons of Sn2+. Furthermore, with the assistance of acrylamide and acrolein, synergistic enhancement in terms of the antioxidation and suppression of Anderson localization can be achieved — a concept referred to as "Dual Synergistic Engineering". This suppresses the oxidation of Sn2+ and reduces Sn4+ content by ≈76%. Meanwhile, the diffusion length is prolonged significantly from 195.9 to 458.9 nm. The optimized all‐inorganic Sn/Pb‐based perovskite solar cells exhibit a power conversion efficiency of above 14% with enhanced stability. These findings provide an alternative viewpoint for comprehending the impact of chemical interaction on oxidation and crystal growth in Sn/Pb‐based perovskites. [ABSTRACT FROM AUTHOR]

Abstract The imaging reactions of resist materials used for nano-patterning have become radiation-chemical reactions, with the shortening of wavelengths of the exposure light sources in lithography systems. The most widely used patterning materials in industrial lithography are chemically amplified resists (CAR). Understanding the deprotonation mechanism of ionized polymers (radical cations) is important for acid generation in CARs. In this study, the dynamics of radical cations in poly(4-hydroxystyrene) (PHS)–type resist polymers, partially and totally protected by tert-butoxycarbonyl (t-BOC) groups, are investigated using a combination of electron pulse radiolysis experiments, acid yield measurements, and quantum chemical calculations. The t-BOC(oxy) group exhibits π-electron-donating behavior in the monomer cation but changes to electron-accepting behavior in the polymer cation, owing to the interaction between substituents. The destabilization of radical cations due to decreased intramolecular charge resonance may contribute to the high deprotonation efficiency of t-BOC-capped PHS polymers.

Multiply substituted pyrroles are found in medicines, natural products, and functional materials. A general method for introducing functionality on the pyrrole ring is thus required. Herein, a regiocontrolled halogen dance reaction and an in situ transmetalation of α-functionalized bromopyrroles are reported. Selective generation of the isomeric pyrrolylmetal species was achieved by using an ethyl ester or a phenyl group at the α-position of the pyrrole and by switching between the halogen dance reaction and in situ transmetalation. These reactions proceeded smoothly when an N , N -dimethylsulfamoyl group was attached to the pyrrole nitrogen atom, providing the corresponding products in 68% to quantitative yields on 1-mmol scale. This method was applicable to the formal synthesis of Kendine 91. [ABSTRACT FROM AUTHOR]

Oxygen vacancy engineering is a promising strategy to enhance the electrocatalytic activities in conventional metal oxide electrocatalysts. However, the utilization of oxygen vacancies in high‐entropy oxides remains unknown, primarily due to the challenges associated with facile introduction of the oxygen vacancies and explanation of their roles in complex high‐entropy systems. Herein, the facile introduction of oxygen vacancies into high‐entropy oxides is realized and the unique high entropy‐driven role of oxygen vacancies for oxygen evolution reaction (OER) process is revealed. A low‐temperature surface carbonization–decarbonization approach is developed to introduce and regulate the oxygen vacancies in high‐entropy spinel oxides (HEOs). The oxygen vacancies in HEOs can both facilitate pre‐oxidation process for faster OH− adsorption and induce the unique bridge site pathway for easier deprotonation, distinctive in conventional oxides where oxygen vacancies favor *OH adsorption yet hinder the deprotonation. Consequently, the as‐prepared high‐entropy spinel oxides with oxygen vacancies (HEOs‐Ov) exhibit superior OER activities, outperforming the HEOs and most reported oxide‐based electrocatalysts. Besides, this universal method can be extended to other spinel oxides with different configuration entropies and can be scaled up. The work paves the way for the exploration of oxygen vacancies in high‐entropy oxides toward electrocatalysis fields. [ABSTRACT FROM AUTHOR]

Using voltammetry to readout potentiometrically the solution acidity requires easy pH tunability of the probe's redox properties. In this work, tri‐hydroxyphenyl porphyrin (POH3) was synthesized as the electrochemically active probe to develop a voltammetrically potentiometric sensor (VPS) with a pH‐sensitive response. By comparing POH3 with control di‐ and mono‐hydroxyphenyl porphyrins (POH2 and POH1), we found that protonation of the pyrrole macrocycle, electron communication of the para‐hydroxyl groups with the pyrrole nitrogens during structure tautomerization, and the presence of multiple ionizable hydroxyl groups are the critical factors to report reversibly the pH‐sensitive VPS response at the appropriate potential range. Common metal ions have negligible effects on the sensor performance. In comparison to the conventional potentiometric sensor (CPS), our VPS strategy benefits from the advantage that the electrode modification is not required. Thus, the complex phase boundary models necessary for CPS are unnecessarily involved in explaining the potential response. [ABSTRACT FROM AUTHOR]

Commercially available and air- and moisture-stable rhodium complex [Rh(OH)(cod)]2 (2) was utilized in the synthesis of [RhX(cod)(NHC)] (3). The presence of an OH group in complex 2 serves as an internal base, facilitating the deprotonation of the C–H bond of the azolium ring in the hydroxyamide-substituted benzimidazolium salt 1. This reaction between 1 and 2 proceeded in THF at room temperature without temperature control, affording the desired NHC/Rh complex 3 in excellent yield. The characterization of complex 3 was accomplished through NMR and HRMS analyses, revealing its existence as a diastereomeric mixture of two NHC/Rh complexes. Furthermore, its catalytic performance was briefly evaluated in the reaction between 2-naphthaldehyde (5) and phenylboronic acid (6). [ABSTRACT FROM AUTHOR]

UV light-induced photodegradation of the organic–inorganic hybrid (OIH) Ruddlesden–Popper (RP) perovskite nanoplates (NPls) is a crucial bottleneck for optoelectronic application in the future. Continuous UV exposure triggers the deprotonation of the spacer as well as the A-site cation (CH3NH3+), ultimately leading to lattice collapse. To combat this photoinstability, we introduce a surface modification of colloidal OIH RP NPls, (OAm)2(CH3NH3PbI3)2PbI4 (n = 3) (OAm stands for oleylammonium cation) by 4-fluorobenzylammonium iodide (4FBAI). In ambient conditions, conventional NPls deteriorate within 80 min of UV exposure, whereas the 4FBAI-modified NPls exhibit remarkable endurance, maintaining structural integrity for 12 h with only a 11% reduction in the initial photoluminescence (PL). Interestingly, benzylammonium iodide (BAI) and 4-methoxybenzylammonium iodide (4OBAI)-treated NPl fail to provide similar photostability, thus signifying the importance of the fluorine atom. The fluorine atom enhances the positive charge density of the ammonium ion and facilitates faster deprotonation compared to parental ammonium ions (here, OAm+ and CH3NH3+) under UV exposure. This ensures the survival of the parent nanoplate structure. Along with the photostability enhancement, the PL quantum yield of the treated NPl also increases to 50 ± 2 from 35 ± 2%. This research not only addresses the pressing photostability issue of RP NPl stability but also illuminates the pivotal role of specific chemical modifications, such as fluorine atom incorporation, for the fabrication of UV-stable perovskite devices in the future. [ABSTRACT FROM AUTHOR]

Citric acid (citH4) is a ubiquitous product in nature with an interesting chemistry owing to its three carboxy and one hydroxy groups, which can be deprotonated in a stepwise manner into six kinds of citrate anions involving two protonation isomers. Deprotonated citrates easily coordinate to late‐3d‐metal ions (Mn, Fe, Co, Ni, Cu, and Zn), affording complexes including mono‐, di‐, tri‐, tetra‐, hexa‐, hepta‐, octa‐, nona‐, and 21‐nuclear complexes with a variety of structures. Magnetic interactions between metal centers are mainly generated via superexchange through hydroxylate or carboxylate bridging, whereas weaker magnetic dipole interactions appear in the absence of superexchange interactions. In citrate complexes, both ferromagnetic and antiferromagnetic interactions have been found. Citrate has a great potential to serve as a bridge between spin quantum magnetism and green chemistry. In this review, the structures and magnetism of discrete citrate complexes of late‐3d‐metals, as well as their single‐molecule magnet properties are discussed. [ABSTRACT FROM AUTHOR]

Metal Organic Frameworks (MOFs) are organic‐inorganic hybrid materials with exceptionally customizable composition and properties. MOFs intrinsically possess open metal sites, tunable pore size/shape and an ultra‐large specific surface area, and have obtained significant attention over the past 30 years. Furthermore, through the integration of functional moieties such as, molecules, functional groups, noble metal clusters and nanocrystals or nanoparticles into MOFs, the resulting composites have greatly enriched the physical and chemical properties of pure MOFs, enabling their application in a wider range of fields. Triethylamine (TEA) as an organic base has consistently played a fundamental role in the development of MOFs. In this Concept, the versatility of triethylamine when involved in the synthesis of MOFs is discussed. Four sections are used to elaborate on the role of TEA including: (1) Single crystal synthesis; (2) Size and morphology control; (3) Counterion of MOFs; (4) MOFs composites synthesis. In the last part, we highlight the potential of TEA for further developments. [ABSTRACT FROM AUTHOR]

This document presents the results of a study on the regioselective deprotonation of brominated pyridylthiophene compounds. The researchers found that the position of deprotonation could be switched by adding DMPU as a Lewis base, allowing for the selective deprotonation of each proton on the thiophene moiety. The subsequent halogen dance reaction resulted in the synthesis of four iodinated isomers from a single starting material. This method has potential applications in the synthesis of various substituted pyridylthiophene derivatives. The study was conducted at NAIST and supported by the ARIM Program of MEXT, Japan. [Extracted from the article]

Advancing the use of alkali‐metal alkoxides as additives to activate organometallic reagents, here we report the synthesis and characterization of a novel potassium zincate [{(PMDETA)KZn(OtBu)Et2}2] obtained by co‐complexation of equimolar amounts of potassium tert‐butoxide, diethyl zinc and the tridentate donor PMDETA (N,N,N',N",N"‐pentamethyldiethylenetriamine). Demonstrating its ability to activate both of the Et groups towards alkyne C−H metalation, this zincate reacts at room temperature with 2 equivalents of phenylacetylene to furnish [(THF)2KZn(CCPh)2(OtBu)}2], whereas, for the homometallic [ZnEt2(TMEDA)] (TMEDA=N,N,N',N'‐tetramethylethylendiamine) only one Et group is reactive towards the same substrate under the same conditions. Investigations on the reactivity of these complexes to undergo N−H amine metalation using 2, 6‐diisopropylphenylamine (NH2Dipp) and 1,2,3,4‐tetrahydroquinoline (THQ(H)) as model substrates revealed that while homometallic [ZnEt2(TMEDA)] is completely inert towards these amines, heterobimetallic [{(PMDETA)KZn(OtBu)Et2}2] reacts through one of its Et groups to form [(THF)2KZn(OtBu)(Et)(NHDipp)] as well as [(THF)4K2Zn(THQ)4]. The latter is obtained as a side product of ligand redistribution of a putative [(THF)nKZn(OtBu)(Et)(THQ)] intermediate. An alternative method to access mixed amide/alkoxide potassium zincates is also described by assessing the co‐complexation of KOtBu with Zn(HMDS)2 in the presence of PMDETA which gave [(PMDETA)KZn(HMDS)2(OtBu)]. [ABSTRACT FROM AUTHOR]

The intricate nature of the surface structure of carbon dots (CDs) hinders a comprehensive understanding of their emission behavior. In this study, we employ two types of CDs created through acid‐alkali treatments, one with surface protonation and the other with surface deprotonation, with the objective of investigating the impact of these surface modifications on carrier behavior using ultrafast spectroscopy techniques. TEM, XRD, FTIR and Raman spectra demonstrate the CDs' structure, featuring graphitic core and abundant surface functional groups. XPS confirms the successful surface modifications of CDs via protonation and deprotonation. Ultrafast transient absorption (TA) spectroscopy reveals that deprotonation modification may decelerate the relaxation process, thereby increasing the visible PL quantum yields (PLQY). Conversely, protonation may accelerate the relaxation process due to the induced low‐energy absorption band, resulting in self‐absorption and reduced PLQY. Furthermore, TA analysis of CDs in mixed solvents with different proportions of ethanol shows the beneficial effect of ethanol in decelerating the relaxation process, leading to an increased PLQY of 33.7 % for deprotonated CDs and 22.1 % for protonated CDs. This study illuminates the intricate relationship between surface deprotonation/protonation modifications and carrier behavior in CDs, offering a potential avenue for the design of high‐brightness CDs for diverse applications. [ABSTRACT FROM AUTHOR]

Chelating agents are commonly employed in microelectronic processes to prevent metal ion contamination. The ligand fragments of a chelating agent largely determine its binding strength to metal ions. Identification of ligands with suitable characteristics will facilitate the design of chelating agents to enhance the capture and removal of metal ions from the substrate in microelectronic processes. This study employed quantum chemical calculations to simulate the binding process between eleven ligands and the hydrated forms of Ni2+, Cu2+, Al3+, and Fe3+ ions. The binding strength between the metal ions and ligands was quantified using binding energy and binding enthalpy. Additionally, we explored the binding interaction mechanisms and explained the differences in binding abilities of the eleven ligands using frontier molecular orbitals, nucleophilic indexes, electrostatic potentials, and energy decomposition calculations based on molecular force fields. Based on our computational results, promising chelating agent structures are proposed, aiming to guide the design of new chelating agents to address metal ion contamination issues in integrated circuit processes. [ABSTRACT FROM AUTHOR]

Reduced isotropic Raman spectra of dilute sodium glycolate in aqueous solutions of NaOH (molalities ranging from 0.03 to 5.65 mol·kg−1 in OH−) have been obtained at temperatures 5, 25, and 45 °C. The Raman spectra yielded evidence of the formation of a doubly-deprotonated glycolate dianion, −O–CH2–COO− (Gly2−) from the decrease in the intensity of the hydroxyl O–H bending mode at 1365 cm−1 with increasing basicity, and the 7 cm−1 shift in the alcohol C–OH stretching mode (from 1079 to 1086 cm−1 at 5 °C). Equilibrium quotients for the second ionization constant of glycolic acid, Q2a,OH, which corresponds to the deprotonation of the glycolate hydroxyl group, were calculated from the peak area of the O–H bending mode as it decreased with higher NaOH molalities. Values for the equilibrium constant and the standard molar enthalpy of reaction at 25 °C: log K2a,OH,298 = − 1.143 ± 0.059, and ΔionH°2a,OH,298 = − 12.5 ± 1.6 kJ·mol−1, were determined by regressing the experimental equilibrium quotients to a simple extended Debye–Hückel activity coefficient model. This is the first reported spectroscopic characterization of Gly2−and the first reported values for log K2a,OH,298 and ΔionH°2a,OH,298. [ABSTRACT FROM AUTHOR]

Abstract Aqueous rechargeable batteries using abundant multi‐ion cations have received increasing attention in the energy storage field for their high safety and low cost. Layered double hydroxides (LDHs) possess a two‐dimensional structure and exhibit great potential as cathodes for multi‐ion intercalation. However, the insufficient active sites of LDHs result in low capacities in the discharging process. Interestingly, the LDHs after the deprotonation process exhibit favorable electrochemical performance of multi‐cation intercalation. The deprotonation process of LDHs has been widely found in the oxygen evolution reaction and energy storage field, where LDHs lose H in laminates and converts to deprotonated γ‐phase MOOHs (MOOs). Herein, we take a comprehensive overview of the dynamics structure transformation of the deprotonation process of LDHs. Furthermore, the development of advanced aqueous battery cathode and metal battery anode based on deprotonated LDHs for energy storage is explored and summarized. Finally, the perspective of deprotonated LDHs in the energy storage field is discussed.

Commercially available and air- and moisture-stable rhodium complex [Rh(OH)(cod)]2 (2) was utilized in the synthesis of [RhX(cod)(NHC)] (3). The presence of an OH group in complex 2 serves as an internal base, facilitating the deprotonation of the C–H bond of the azolium ring in the hydroxyamide-substituted benzimidazolium salt 1. This reaction between 1 and 2 proceeded in THF at room temperature without temperature control, affording the desired NHC/Rh complex 3 in excellent yield. The characterization of complex 3 was accomplished through NMR and HRMS analyses, revealing its existence as a diastereomeric mixture of two NHC/Rh complexes. Furthermore, its catalytic performance was briefly evaluated in the reaction between 2-naphthaldehyde (5) and phenylboronic acid (6).

In contrast, under thermodynamically controlled reaction conditions (60 °C, 10 min) in a flow reactor with (Cy SB 2 sb N) SB 2 sb Zn-2LiCl, zincation proceeds preferentially at the C4-position (Scheme 9). In 2007, the Knochel group demonstrated metalation of a 2-chloro-3-nitropyridine ( B 40 b ) with (TMP) SB 2 sb Zn-2MgCl SB 2 sb -2LiCl B 2 b at -40 °C in 1.5 h followed by a subsequent copper-catalysed allylation with 3-bromocyclohexane (Scheme 10); the final product B 42 b was obtained in 80% yield. [19] Thus for most purposes, TMPZnCl-LiCl B 3 b remains the most convenient and widely applicable zinc base, and has come to be termed a "turbo-zinc" reagent. [59] Sales et al. tested both MgTMP and ZnTMP bases and found that the use of TMP SB 2 sb Zn-2MgCl SB 2 sb -2LiCl B 2 b not only results in higher yields than with TMPMgCl-LiCl (93% I vs. i 65%), but also the reaction proceeds at room temperature rather than at -30 °C. [Extracted from the article]

This work reveals a schematic strategy to massively fabricate a series of OH-riched copper oxides (CuO-OH), which could be used as highly efficient chemo catalysts for water oxidation reaction (WOR). The results indicate that the as-prepared CuO-OH exhibited excellent catalytic activity (2,900 µmol·h−1·g−1) toward water oxidation, far higher than the pure CuO formed through calcination. According to the radical capture results and the DRIFTS, XRD, and Raman spectra data, sulfate radicals were the main active species. Subsequent data of BET, HR-TEM, and FT-IR spectra reveal that the CuO-OH could activate persulfate ions in the dark to produce sulfate radicals efficiently at room temperature and promote the sulfate radicals to carry out immediately to hydroxide-mediated deprotonation steps in WOR. Based on the results above, a mechanism is proposed. [ABSTRACT FROM AUTHOR]

A 12‐membered zwitterionic tetrastanna(II) cycle 1 having a crown ether‐like topology has been isolated from the deprotonation of 1,1′‐methylenediimidazole (B) with two equivalents of Sn[N(SiMe3)2]2 (A). The solid‐state structure and NMR analysis confirms the tetrastanna(II) cycle 1 to be comprised of two stannate(II) and two stannyliumylidene ion pairs in alternating positions of the heterocycle. Computational analysis shows greater nucleophilicity at the proximally located stannate(II) centers. Nonetheless, the tetrastanna(II) cycle 1 remains poorly reactive due to engagement of SnII lone pair electrons in intramolecular donor‐acceptor interactions. Simple deprotonation reaction between Sn[N(SiMe3)2]2 (A) and N‐(diisopropylphenyl)imidazole (C) in equimolar ratio has led to a stannylene 2, involving the formation of a Sn−C covalent bond with the anionic imidazol‐2‐yl carbon center along with the release of NH(SiMe3)2. Compound 2 exists as a dimer, where the unsubstituted ring nitrogen atom coordinated intermolecularly to the other stannylene center. [ABSTRACT FROM AUTHOR]

The discovery of melamine by Justus von Liebig was fundamental for the development of several fields of chemistry. The vast majority of compounds with melamine or melamine derivatives appear as adducts. Herein, we focus on the development of novel compounds containing anionic melamine species, namely the melaminates. For this purpose, we analyze the reaction of SbCl3 with melamine by differential scanning calorimetry (DSC). The whole study includes the synthesis and characterization of three antimony compounds that are obtained during the deprotonation process of melamine to melaminate with the reaction sequence from SbCl4(C9N18H19) (1) via (SbCl4(C6N12H13))2 (2) to SbCl(C3N6H4) (3). Compounds are characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), and infrared spectroscopy (IR). The results give an insight into the mechanism of deprotonation of melamine, with the replacement of one, two, or eventually three hydrogen atoms from the three amino groups of melamine. The structure of (3) suggests that metal melaminates are likely to form supramolecular structures or metal-organic frameworks (MOFs).

24 substituted cyanocompounds and the corresponding anions obtained upon H+-abstraction from diverse positions were subjected to an electron density analysis with the quantum theory of atoms in molecules (QTAIM). All the electron densities were obtained at the B3LYP/6–31 + + G(2d,2p) level on completely optimized geometries. In accordance to experimental evidence, α-H+ abstraction is found as the most favored one (by at least 100 kJ mol−1 in all the tested compounds). The presence of additional resonance electron attractors reduces significantly the α-deprotonation energy, whereas this magnitude is quite insensitive to the inclusion of resonance electron donors. The electron density rearrangement accompanying the deprotonation is apparently in line with the predictions of the resonance model (RM). In fact, a significant part of the electron density gained by expelling the proton is transferred to cyano N and to other groups where significant resonance structures delocalize the negative charge. Nevertheless, some significant modifications have to be introduced on the RM picture when the QTAIM results are studied in detail. [ABSTRACT FROM AUTHOR]

The preservative qualities of individual ionic compounds impacting the infectivity of T4 virions were elucidated. T4 virions were immersed in quasi-pure ionic solutions prior to the adsorption process, and the plaque forming unit (pfu) values of these were measured following the conventional method. In neutral ionic solutions, the minimum and the optimum concentrations of preservative qualities corresponded with the results obtained from the multi-ionic media/buffers. In acid and alkali solutions, phages show tolerances at a pH range of 5–11 in multi-ionic media/buffers. T4 virions show no tolerance in quasi-pure acid, neutral, and weak alkaline conditions. The preservative quality of T4 virions increased in over 10−1 mM OH− solution, equivalent to a pH value over 10, which corresponds to the pKa of the deprotonation of the DNA bases G and T. Infectivity was lost below 10−1 mM OH− and higher than 10 mM OH−. These results imply that maintaining infectivity of a virion may need the flexibility of the intra-capsid DNA by deprotonation. [ABSTRACT FROM AUTHOR]

N,N'‐dihydroxy‐1,4,5,8‐naphthalenetetracarboxdiimide (NDI−(OH)2) has attracted much attention in recent years, because its doubly deprotonated state, (O−NDI−O)2−, has metal‐coordination ability and characteristic electronic transition useful for designing electronic and optical functions. In contrast, a molecular crystal with the mono‐deprotonated (HO−NDI−O)− ion remains unknown. We herein report an organic crystal containing non‐disproportionated (HO−NDI−O)− ions, which are connected by very strong O−H−O hydrogen bonds. Its lowest energy absorption band (450 to 650 nm) is observed in between that of NDI−(OH)2 (380 nm) and isolated (O−NDI−O)2− (500 to 850 nm) species, consistent with the molecular orbital calculations. This absorption originates from the electronic transition from deprotonated imide‐based orbitals to NDI‐core orbitals, which can be influenced by the hydrogen bonds around imide group. Consequently, the optical properties of NDI−(OH)2 can be modulated by the stepwise deprotonation and hydrogen‐bonding interactions. [ABSTRACT FROM AUTHOR]

The pH dependences of the photoluminescence of carbon dots synthesized by the hydrothermal method with polyfunctional and monofunctional (carboxylated and hydroxylated) surfaces have been studied. As a result of the analysis of the obtained photoluminescence and absorption spectra of aqueous suspensions of all studied types of carbon dots at different pH values, a significant effect of the acidity of the environment of nanoparticles on their optical properties was found. It has been found that the greatest changes in the spectral characteristics of absorption and photoluminescence of carbon dots with COOH, OH, and NH2 surface groups appear in the pH ranges of 2–5 and 8–12. The obtained results are explained are explained by the processes of protonation/deprotonation of the surface groups of carbon dots. [ABSTRACT FROM AUTHOR]

Chelating agents are commonly employed in microelectronic processes to prevent metal ion contamination. The ligand fragments of a chelating agent largely determine its binding strength to metal ions. Identification of ligands with suitable characteristics will facilitate the design of chelating agents to enhance the capture and removal of metal ions from the substrate in microelectronic processes. This study employed quantum chemical calculations to simulate the binding process between eleven ligands and the hydrated forms of Ni2+, Cu2+, Al3+, and Fe3+ ions. The binding strength between the metal ions and ligands was quantified using binding energy and binding enthalpy. Additionally, we explored the binding interaction mechanisms and explained the differences in binding abilities of the eleven ligands using frontier molecular orbitals, nucleophilic indexes, electrostatic potentials, and energy decomposition calculations based on molecular force fields. Based on our computational results, promising chelating agent structures are proposed, aiming to guide the design of new chelating agents to address metal ion contamination issues in integrated circuit processes.

[Display omitted] Metal-organic frameworks (MOFs) with conjugation carboxylate ligands as electrocatalysts can significantly improve oxygen evolution reaction (OER), but the role of π-interaction on the reactive sites of OER is often neglected. We intend to unravel the mechanism of how π-interaction enhances OER performance. The results of Rietveld refinement, density functional theory (DFT) calculations, and in-situ Raman spectra show that π-interaction can efficiently modulate the local spin configuration of metal centers, facilitate γ-Ni 1-x Fe x OOH active species with high-valence Ni sites modified by high-spin Fe, accelerate electron transfer, optimize the d-band center together with the beneficial rate-determining step of OER. NiFe-BPDC MOFs/NF with 0.8559 eV π-interaction energy generated γ-Ni 1-x Fe x OOH in only 60 s at 1.4 V, demonstrating that π-interaction promotes the rapid generation of highly active reactive sites. Furthermore, the results of in-situ Raman and electron paramagnetic resonance (EPR) spectra reveal that the deprotonation and deoxygenation steps of OER are accompanied by changes in the oxidation state of metal ions and the generation of oxygen vacancies on the surface of catalysts. In addition, NiFe-BPDC MOFs/NF rapidly completes the deprotonation and deoxygenation steps, and it requires only 288 mV overpotential to reach 100 mA/cm2 with 100 h of stability, suggesting promising industrial application. [ABSTRACT FROM AUTHOR]

A novel, selective and high‐yielding palladium‐catalyzed carbonylative arylation of a variety of weakly acidic (pKa 25–35 in DMSO) benzylic and heterobenzylic C(sp3)−H bonds with aryl bromides has been achieved. This system is applicable to a range of pro‐nucleophiles for access to sterically and electronically diverse α‐aryl or α,α‐diaryl ketones, which are ubiquitous substructures in biologically active compounds. The Josiphos SL‐J001‐1‐based palladium catalyst was identified as the most efficient and selective, enabling carbonylative arylation with aryl bromides under 1 atm CO to provide the ketone products without the formation of direct coupling byproducts. Additionally, (Josiphos)Pd(CO)2 was identified as the catalyst resting state. A kinetic study suggests that the oxidative addition of aryl bromides is the turnover‐limiting step. Key catalytic intermediates were also isolated. [ABSTRACT FROM AUTHOR]

The discovery of melamine by Justus von Liebig was fundamental for the development of several fields of chemistry. The vast majority of compounds with melamine or melamine derivatives appear as adducts. Herein, we focus on the development of novel compounds containing anionic melamine species, namely the melaminates. For this purpose, we analyze the reaction of SbCl3 with melamine by differential scanning calorimetry (DSC). The whole study includes the synthesis and characterization of three antimony compounds that are obtained during the deprotonation process of melamine to melaminate with the reaction sequence from SbCl4(C9N18H19) (1) via (SbCl4(C6N12H13))2 (2) to SbCl(C3N6H4) (3). Compounds are characterized by single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), and infrared spectroscopy (IR). The results give an insight into the mechanism of deprotonation of melamine, with the replacement of one, two, or eventually three hydrogen atoms from the three amino groups of melamine. The structure of (3) suggests that metal melaminates are likely to form supramolecular structures or metal-organic frameworks (MOFs). [ABSTRACT FROM AUTHOR]

The reaction of magnesium turnings and 6,6‐di‐para‐tolylpentafulvene was investigated. Under mild conditions, the magnesium dissolves, forming the MgII complex 1 with a π‐η5 : σ‐κ1 coordinating ligand of the dimerized pentafulvene, analyzed by NMR and XRD investigations. As a magnesium pentafulvene complex was a possible intermediate, amines were employed as intercepting agents. Thereby, the amines were formally deprotonated by elemental magnesium, yielding the first examples of Cp'Mg(THF)2NR2 complexes. This reaction competes with the formation of 1 and a consecutive formal [1,5]‐H‐shift forming an ansa‐magnesocene. Employing amines with low basicity gave quantitative conversion to the amide complexes. [ABSTRACT FROM AUTHOR]

Beta vulgaris L. is a biennial plant easily accessible all over the world, rich in various biologically active compounds, especially a class of extremely bioactive pigments known as betalains. These dyes predominate in the pulp and peels of beetroot, which is why they can be valorized in food, medicine or in the textile industry. In this work, betalains extractions were carried out applying 3 sustainable options: (1) dissolving/solubilizing betalains in water; (2) extraction under pressure; (3) extraction assisted by an enzyme/pectinase. The obtained extracts were analyzed in the UV-Vis domain, which allowed their characterization by determining the total monomeric anthocyanins, color density (control), polymeric density and browning index. The HPLC-MS analysis highlighted the extracts composition. The colors characteristics were determined through CIELab measurements. The performances of these 3 extracts, during green dyeing (without mordants), were evaluated according to the color characteristics (L*, a*, b* and K/S) of the dyed wool samples under different conditions: pH, temperature, duration of dyeing and volume of extract and stabilizers (Vitamin E and EDTA). Betalains can be considered acid dyes, with a low affinity for wool, which in a pronounced acidic environment dye the wool in an intense, uniform way and with good resistance to washing and rubbing. [ABSTRACT FROM AUTHOR]

Air fabrication of efficient and stable perovskite solar cells with substantial reproducibility is of importance for commercialization of perovskite solar cells. There has been little consensus on which halide is the best selection for thin 2D perovskite layer on 3D perovskite when processing in ambient air. In this work, the influence of humidity and halide ions in alkylammonium halide (OAX)‐treated perovskite layer on photovoltaic performance is investigated. The authors find that a combination of high humidity and the presence of chloride ions can induce the deprotonation of methylammonium (MA+) ions. With X‐ray diffraction, cross‐sectional scanning electron microscope, Fourier‐transform infrared spectroscopy, the authors elucidate that the deprotonation reaction in the octylammonium chloride (OACl)‐treated perovskite layer makes MA+ ions (CH3NH3+) volatile MA (CH3NH2), which results in void volumes and defects in the bulk of perovskite layer as well as at the interface. The defective perovskite solar cells induced by the deprotonation reaction have the suppressed hole transfer at the interface between the perovskite layer and the hole transport layer, yielding the reduced internal quantum efficiency and JSC. Space charge‐limited current analysis reveals that the reduced VOC is caused by the high trap density estimated from VTFL of hole‐only devices. [ABSTRACT FROM AUTHOR]

Scale inhibitors are effective in preventing CaCO3 scaling in geothermal systems, but the scale inhibition performance and price of commercial scale inhibitors in high‐temperature and high‐salinity water are still not ideal. In this work, a novel modified carboxymethylated β‐cyclodextrin tetrameric (CAAS) scale inhibitor was synthesized using carboxymethylated β‐cyclodextrin, acrylic acid, 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS), and p‐styrenesulfonate (SSS) by free radical polymerization, and deprotonated CAAS (D‐CAAS) was prepared based on CAAS. The results of the static test showed that the CaCO3 scale inhibition efficiency of D‐CAAS reached 90.8% at 100°C and 800 mg/L Ca2+. Compared with that of previous commercial scale inhibitors, the scale inhibition efficiency of D‐CAAS was increased by 13.5%, and the price can be decreased by 26.1%. The results of SEM, XRD and molecular dynamics (MD) simulation showed that at 100°C–120°C, the deprotonation of D‐CAAS enhanced the weak interaction between D‐CAAS and CaCO3, inducing the transformation between calcite and vaterite and forming a loose scale. Deprotonation weakens the hydrogen bond between D‐CAAS and water to reduce the energy required for the binding of D‐CAAS to the surface of CaCO3. This study is expected to provide a low‐cost and high‐efficiency CaCO3 scale inhibitor for geothermal applications. [ABSTRACT FROM AUTHOR]

The deprotonative functionalization of α,α‐difluoromethyl ketones is described herein. Using a catalytic organosuperbase and a silane additive, the corresponding difluoroenolate could be generated and trapped with aldehydes to deliver various α,α‐difluoro‐β‐hydroxy ketones in high yields. This new strategy tolerates numerous functional groups and represents the access to the difluoroenolate by direct deprotonation of the difluoromethyl unit. The diastereoselective version of the reaction was also investigated with d.r. up to 93 : 7. Several transformations were performed to demonstrate the synthetic potential of these α,α‐difluoro‐β‐hydroxy ketones. In addition, this method has been extended to the use of other electrophiles such as imines and chalcogen derivatives, and a difluoromethyl sulfoxide as nucleophile, thus leading to a diversity of difluoromethylene compounds. [ABSTRACT FROM AUTHOR]

Betanidin (Bd) is a nitrogenous metabolite with significant bioactive potential influenced by pH. Its free radical scavenging activity and deprotonation pathway are crucial to studying its physicochemical properties. Motivated by the published discrepancies about the best deprotonation routes in Bd, this work explores all possible pathways for proton extractions on that molecule, by using the direct approach method based on pKa. The complete space of exploration is supported by a linear relation with constant slope, where the pKa is written in terms of the associated deprotonated molecule energy. The deprotonation rounds 1, ..., 6 define groups of parallel linear models with constant slope. The intercepts of the models just depend on the protonated energy for each round, and then the pKa can be trivially ordered and explained by the energy. We use the direct approximation method to obtain the value of pKa. We predict all possible outcomes based on a linear model of the energy and some related verified assumptions. We also include a new measure of similarity or dissimilarity between the protonated and deprotonated molecules, via a geometric–chemical descriptor called the Riemann–Mulliken distance (RMD). The RMD considers the cartesian coordinates of the atoms, the atomic mass, and the Mulliken charges. After exploring the complete set of permutations, we show that the successive deprotonation process does not inherit the local energy minimum and that the commutativity of the paths does not hold either. The resulting clusterization of pKa can be explained by the local acid and basic groups of the BD, and the successive deprotonation can be predicted by using the chemical explained linear models, which can avoid unnecessary optimizations. Another part of the research uses our own algorithm based on shape theory to determine the protein's active site automatically, and molecular dynamics confirmed the results of the molecular docking of Bd in protonated and anionic form with the enzyme aldose reductase (AR). Also, we calculate the descriptors associated with the SET and SPLET mechanisms. [ABSTRACT FROM AUTHOR]

Abstract Air fabrication of efficient and stable perovskite solar cells with substantial reproducibility is of importance for commercialization of perovskite solar cells. There has been little consensus on which halide is the best selection for thin 2D perovskite layer on 3D perovskite when processing in ambient air. In this work, the influence of humidity and halide ions in alkylammonium halide (OAX)‐treated perovskite layer on photovoltaic performance is investigated. The authors find that a combination of high humidity and the presence of chloride ions can induce the deprotonation of methylammonium (MA+) ions. With X‐ray diffraction, cross‐sectional scanning electron microscope, Fourier‐transform infrared spectroscopy, the authors elucidate that the deprotonation reaction in the octylammonium chloride (OACl)‐treated perovskite layer makes MA+ ions (CH3NH3+) volatile MA (CH3NH2), which results in void volumes and defects in the bulk of perovskite layer as well as at the interface. The defective perovskite solar cells induced by the deprotonation reaction have the suppressed hole transfer at the interface between the perovskite layer and the hole transport layer, yielding the reduced internal quantum efficiency and JSC. Space charge‐limited current analysis reveals that the reduced VOC is caused by the high trap density estimated from VTFL of hole‐only devices.

Optical sensors with distinct colorimetric output upon binding with fluoride offer a convenient, fast and reliable methodology for its on-site detection. Most of such sensors lose their affinity towards fluoride in aqueous medium, limiting their applicability in real time analysis. In this report, we have been successful in selective, ratiometric and naked eye sensing of F− ion in aqueous medium by a pyrrole-benzimidazole conjugate based receptor R, in presence of Ni2+ salt. It is noteworthy that the receptor R interacts with neither F− nor Ni2+ ions alone in aqueous medium. As studied by UV–Vis spectroscopy and EPR analysis, the sensing mechanism involves F− induced deprotonation of the receptor R, followed by the formation of an in-situ Ni(II) complex, [Ni(II)R2]2−. This complex is responsible for the colorimetric change from dark yellow to tangerine orange. The structure of the complex is further elucidated by DFT calculations. The limit of detection (LOD) is found to be 0.98 ppm.

N -Sulfinyl metalloenamines, generated by deprotonating α-linear N - tert -butanesulfinyl ketimines, reacted with nitroalkenes via stereoselective conjugate addition to give Michael adducts with opposite stereochemistry to that obtained using α-branched sulfinylketimines. In the presence of excess base (2.5 equiv t -BuOK), the adducts derived from α-linear ketimines were further stereoselectively deprotonated to afford the corresponding kinetically favorable N -sulfinyl (Z)-enamine derivatives in good yields with good stereoselectivities. A reaction model was proposed to rationalize the observed stereochemistry. [ABSTRACT FROM AUTHOR]

The thermal behaviour of an uvite from San Piero in Campo (Elba Island, Italy) was investigated at room pressure through in situ high-temperature powder X-ray diffraction (PXRD), until the breakdown conditions were reached. The variation of uvite structural parameters (unit-cell parameters and mean bond distances) was monitored together with site occupancies and we observed the thermally induced Fe oxidation process counterbalanced by (OH)− deprotonation, which starts at 450 °C and is completed at 650 °C. The uvite breakdown reaction occurs between 800 and 900 °C. The breakdown products were identified at room temperature by PXRD and the breakdown reaction can be described as follows: tourmaline → indialite + yuanfuliite + plagioclase + “boron-mullite” phase + hematite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and synthesis of compound 1 (single nitro-substituent) and compound 2 (three nitro substituents). • Detection of cyanide in aqeous medium via hydrogen bonding in 1 , whereas Michael addition reaction in 2. • Change in the mode of binding of a specific analyte, merely by changing the number of un-reactive substituents. • Furthermore, a library of BIM compounds with different number of nitro groups at different positions (total 12) were designed for evaluation of anti-tubercular activity. • Detailed computational and docking studies for the cyanide detection mechanism and prediction of anti-tubercular activity of the BIM compounds. A pair of bisindolyl methane (BIM) compounds (1 and 2) were designed and their colorimetric response towards cyanide (CN−) ions were investigated in detail. In aqueous medium, the compound with single nitro-substituent (1) showed blue-shifted absorption maxima upon addition of cyanide ion, resulting in change in solution color from pink to yellow. On the contrary, the compound with three nitro functional groups (2), exhibited hypochromic shift along with initial, blue-shifted absorption maxima (color changed from pink to yellow to colourless). The mechanistic investigation indicated that the former observation could be attributed by cyanide-mediated hydrogen bonding interaction (or deprotonation), while the latter might be caused due to the Michael addition reaction. Interestingly, at alkaline pH, chemodosimetric interaction was observed with both the probe molecules. However, the rate of interaction was much faster for compound 2 than that observed for 1. A change in the mode of binding of a specific analyte, merely by changing the number of un-reactive substituents, is not much known in the literature. However, it will be extremely beneficial for future engineering of more efficient sensory systems. Furthermore, a library of BIM compounds with various number of nitro groups at different positions (total twelve) were synthesized for evaluation of anti-tubercular activity. Fortunately, some of the compounds were found to be as equally effective as the commercially available anti-tuberculosis drug, ethambutol (MIC: 1.56 µg/mL), whereas the compound 2 displayed a better anti-tubercular response (MIC: 0.78 µg/mL). This observation was further rationalized by docking studies with M. tuberculosis DprE1 in complex with the non-covalent inhibitor QN118. [ABSTRACT FROM AUTHOR]

This study investigated the adsorption mechanisms of boron on protonated and deprotonated graphene with oxygen-containing functional groups. Six representative adsorption conformations of boron predominant species (B(OH) 3 (B3) and B(OH) 4 − (B4)) on graphene were proposed. Protonation and deprotonation of graphene had significant effects on boron adsorption. Deprotonation of hydroxyl-modified (G20-OH) and carboxyl-modified graphene (G20-COOH) with 20 carbon rings decreased B3 and B4 adsorption. Protonation of G20-OH enhanced B3 adsorption. The adsorption interface, mainly around hydrogen atoms associated with protonated groups, exhibited a sharp gradient, due to the increased electron density from O H bond formation. B3 showed stronger electron sharing, emphasizing robust interactions. Hydrogen bonding dominated G20-OH2-B3, while G20-O-B4 exhibited more substantial hydrogen bond interactions. In summary, hydrogen bond strength was crucial in B3 adsorption, while electrostatic repulsion hindered B4 adsorption on deprotonated graphene. These findings highlight the importance of graphene protonated and deprotonated states in effectively removing various pKa contaminants. [Display omitted] • Protonation of hydroxyl-modified graphene enhanced the adsorption of B(OH) 3. • Deprotonation of oxygen-containing groups modified graphene reduced adsorption. • Interaction forces led to differences in the adsorption of B(OH) 3 and B(OH) 4 −. • Hydrogen bond strength played a crucial role in B(OH) 3 adsorption on graphene. • Electrostatic repulsion hindered B(OH) 4 − adsorption on deprotonated graphene. [ABSTRACT FROM AUTHOR]

[Display omitted] • The interactions between amino acid-species and Ca minerals/Ca2+ were investigated. • High Ca2+ concentrations achieved after 3 mins of leaching assisted by amino acids. • Gly's buffering capacity and Ca chelation led to the highest 114.8 g-CaCO 3 /kg-CFA. • Amino acids incorporated in CaCO 3 crystals impact the mineralogy and morphology. An amino acid-mediated Ca2+ leaching-CO 2 mineralization process was proposed to address the challenges associated with slow kinetics and extensive consumption of exogenous reagents in CO 2 mineralization. While the underlying reaction mechanism between amino acid and alkaline minerals/metals remains unclear, this study explored the interactions between amino acid-species and Ca-bearing minerals/Ca2+ by investigating the evolution of active compounds from the perspectives of thermodynamic equilibrium analysis and experimental study. Thermodynamic equilibrium analysis showed that the active Ca-bearing minerals of coal fly ash (CFA) varied in the systems of ammonium salt, acid, and amino acid, e.g., the active phases in glycine were portlandite (Ca(OH) 2), lime (CaO), and gehlenite (2CaO*Al 2 O 3 *SiO 2). High Ca2+ concentrations of 0.26 M, 0.14 M, and 0.1 M can be achieved after 3 min of leaching assisted by amino acids of Glycine (Gly), L-Alanine (Ala), and L-Arginine (Arg), respectively, which implied the kinetics and thermodynamical feasibility. This phenomenon was demonstrated to relate to the fact that Gly and Ala had minimal pH buffering capacity in the early leaching stage. The deprotonated forms of Gly and Ala with a higher affinity with Ca2+ increased from 0.03 % and 0.04 % to 33.9 % and 12.88 %, respectively, thereby promoting Ca2+ leaching. The Ca2+ utilization efficiencies from CFA were 26.45 %, 15.0 %, and 13.3 % for Gly, Ala, and Arg, respectively. Gly achieved the best CaCO 3 yield of 114.8 g/kg, due to the combined effects of Gly's buffering capacity and strong chelation effect for Ca2+, which drove forward the dissolution of the active phase and precipitation of CaCO 3. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microencapsulation facilitates the use of vitamins in food applications. • To know the material, the technique, and the release mechanism can ensure the success of microencapsulation. • Microencapsulation prolongs the stability of vitamins for better utilization. • Structurally modified coating materials allow a higher release of vitamins under digestible conditions. Vitamins are responsible for providing biological properties to the human body; however, their instability under certain environmental conditions limits their utilization in the food industry. The objective was to conduct a systematic review on the use of biopolymers and lipid bases in microencapsulation processes, assessing their impact on the stability, controlled release, and viability of fortified foods with microencapsulated vitamins. The literature search was conducted between the years 2013–2023, gathering information from databases such as Scopus, PubMed, Web of Science and publishers including Taylor & Francis, Elsevier, Springer and MDPI; a total of 49 articles were compiled The results were classified according to the microencapsulation method, considering the following information: core, coating material, solvent, formulation, process conditions, particle size, efficiency, yield, bioavailability, bioaccessibility, in vitro release, correlation coefficient and references. It has been evidenced that gums are the most frequently employed coatings in the protection of vitamins (14.04%), followed by alginate (10.53%), modified chitosan (9.65%), whey protein (8.77%), lipid bases (8.77%), chitosan (7.89%), modified starch (7.89%), starch (7.02%), gelatin (6.14%), maltodextrin (5.26%), zein (3.51%), pectin (2.63%) and other materials (7.89%). The factors influencing the release of vitamins include pH, modification of the coating material and crosslinking agents; additionally, it was determined that the most fitting mathematical model for release values is Weibull, followed by Zero Order, Higuchi and Korsmeyer-Peppas; finally, foods commonly fortified with microencapsulated vitamins were described, with yogurt, bakery products and gummy candies being notable examples. [ABSTRACT FROM AUTHOR]

The preservative qualities of individual ionic compounds impacting the infectivity of T4 virions were elucidated. T4 virions were immersed in quasi-pure ionic solutions prior to the adsorption process, and the plaque forming unit (pfu) values of these were measured following the conventional method. In neutral ionic solutions, the minimum and the optimum concentrations of preservative qualities corresponded with the results obtained from the multi-ionic media/buffers. In acid and alkali solutions, phages show tolerances at a pH range of 5–11 in multi-ionic media/buffers. T4 virions show no tolerance in quasi-pure acid, neutral, and weak alkaline conditions. The preservative quality of T4 virions increased in over 10−1 mM OH− solution, equivalent to a pH value over 10, which corresponds to the pKa of the deprotonation of the DNA bases G and T. Infectivity was lost below 10−1 mM OH− and higher than 10 mM OH−. These results imply that maintaining infectivity of a virion may need the flexibility of the intra-capsid DNA by deprotonation.

Dehydrogenation and deprotonation of sucrose and trehalose molecules in vacuum is theoretically studied by using ab initio calculations in the framework of the density functional theory. The differences in the structural, electronic, energetic and vibrational properties of dehydrogenated and deprotonated molecules are discussed, depending on the site from which the hydrogen atom or the proton has been removed. The dehydrogenated molecules are found to be stable, regardless of which hydrogen atom is removed. This contrasts with the instability of the deprotonated molecules, where break-ups or structural reorganizations of the molecule are observed in 20–30% of the cases, but only when the hydrogen atom whose proton is removed was bonded to a carbon atom. Considering the stability and possible rearrangements of the hydrogen network of the deprotonated/dehydrogenated molecule, the formation of additional hydrogen-bridge bonds compared with the nominal molecule appears to be more pronounced for the deprotonated molecules than for the dehydrogenated ones. Moreover, our calculations show that the hydrogen-transfer energy barriers are usually larger for the deprotonated molecules than for the dehydrogenated ones. Finally, compared with the nominal molecule, the vibrational frequency spectrum is shifted to lower frequencies for both the dehydrogenated and the deprotonated molecules.

Phosphine‐catalyzed (4+2) annulation of the acidic hydrogen‐tethered allylic carbonates with electron‐deficient alkenes was achieved. Various electron‐deficient alkenes and allylic carbonates were well tolerated under mild reaction conditions, providing a variety of polysubstituted spirocyclohexenes, spirocyclohexanones or cyclohexanones in moderate to high yields. The scale‐up reactions and further transformations of the products had been performed. The acidic hydrogen‐tethered allylic carbonates displayed nice reactivity and will find more applications. [ABSTRACT FROM AUTHOR]