Electrophilicity index revisited Pal, Ranita; Chattaraj, Pratim Kumar
Journal of computational chemistry,
January 30, 2023, Volume:
44, Issue:
3
Journal Article
Peer reviewed
This review aims to be a comprehensive, authoritative, critical, and accessible review of general interest to the chemistry community; because the electrophilicity index is a very useful global ...reactivity descriptor defined within a conceptual density functional theory framework. Our group has also introduced electrophilicity based new global and local reactivity descriptors and also new associated electronic structure principles, which are important indicators of structure, stability, bonding, reactivity, interactions, and dynamics in a wide variety of physico‐chemical systems and processes. This index along with its local counterpart augmented by the associated electronic structure principles could properly explain molecular vibrations, internal rotations and various types of chemical reactions. The concept of the electrophilicity index has been extended to dynamical processes, excited states, confined environment, spin‐dependent and temperature‐dependent situations, biological activity, site selectivity, aromaticity, charge removal and acceptance, presence of external perturbation through solvents, external electric and magnetic fields, and so forth. Although electrophilicity and its local variant can adequately interpret the behavior of a wide variety of systems and different physico‐chemical processes involving them, their predictive potential remains to be explored. An exhaustive review on all these aspects will set the tone of the future research in that direction.
In the domain of conceptual density functional theory, electrophilicity index is an important descriptor in describing the reactivity of a molecule as a whole. Its local variant, however, provides information about the reactivity of particular atomic sites, thereby analyzing the electrophile‐nucleophile reactions better. Their variation is explained in dynamical processes, excited states, confined environment, spin‐dependent and temperature‐dependent situations, biological activity, site‐selectivity, aromaticity, charge removal and acceptance, presence of external perturbation through solvents, external fields, and so forth.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The importance of inherent substrate reactivity for terpene synthase enzymes is discussed, with a focus on recent experimental tests of predictions derived from computations on gas‐phase reactivity ...of carbocations.
I know what I like: The importance of inherent substrate reactivity for terpene synthase enzymes is discussed in this Minireview. Experimental studies are highlighted that support predictions from quantum chemistry that inherent carbocation reactivity is expressed in the presence of terpene synthase enzymes.
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Birch pollen allergy in Europe Biedermann, T.; Winther, L.; Till, S. J. ...
Allergy (Copenhagen),
July 2019, Volume:
74, Issue:
7
Journal Article
Peer reviewed
Open access
Birch and other related trees of the families Betulaceae and Fagaceae (alder, hazel, oak, hornbeam, chestnut, and beech) constitute the birch homologous group. This grouping is primarily based on the ...extensive IgE cross‐reactivity of allergen homologs to the major birch allergen Bet v 1. Birch pollen is the most dominant tree pollen in Northern and Central Europe and is a major cause of allergic rhinitis and, possibly, asthma symptoms. Over the last few decades, levels of birch pollen have risen and the period of exposure has increased due to climate changes. Subsequently, the prevalence of birch pollen sensitization has also increased. The cross‐reactivity and sequential pollen seasons within the birch homologous group create a prolonged symptomatic allergy period beyond birch pollen alone. Furthermore, many plant food allergens contain homologs to Bet v 1, meaning that the majority of patients with birch pollen allergy suffer from secondary pollen food syndrome (PFS). As a result, the negative impact on health‐related quality of life (HRQoL) in patients allergic to birch pollen is significant. The purpose of this manuscript was to narratively review topics of interest such as taxonomy, cross‐reactivity, prevalence, clinical relevance, PFS, and HRQoL with regard to birch pollen allergy from a European perspective.
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The reactivity of 22 unsaturated molecules undergoing attack by a methyl radical (⋅CH3) have been elucidated using the condensed radical general‐purpose reactivity indicator (condensed radical GPRI) ...appropriate for relatively nucleophilic or electrophilic molecules. Using the appropriate radical GPRI equation for electrophilic attack or nucleophilic radical attack, seven different population schemes were used to assign the most reactive atoms in each of the 22 molecules. The results show that the condensed radical GPRI is sensitive to the population scheme chosen, but less sensitive than the radical Fukui function. Therefore, the reliability of these methods depends on the population scheme. Our investigation indicates that the condensed radical GPRI is most accurate in predicting the dominant products of the methyl radical addition reactions on a variety of unsaturated molecules when the Hirshfeld, Merz–Singh–Kollman, or Voronoi deformation density population schemes are used. Furthermore, for all populations schemes in the majority of instances where the radical Fukui function failed the radical GPRI was able to identify the most reactive atom under certain reactivity conditions.
The reactivity of 22 unsaturated molecules undergoing attack by a methyl radical (⋅CH3) have been elucidated using the condensed radical general‐purpose reactivity indicator (condensed R‐GPRI) appropriate for relatively nucleophilic or electrophilic radicals. The results show that the condensed R‐GPRI and the condensed radical Fukui function are sensitive to the population scheme chosen. The Hirshfeld, Merz–Singh–Kollman (MSK), and Voronoi deformation density (VDD) population schemes are found to be the most reliable in predicting the most likely atom to undergo radical attack in a molecule using the R‐GPRI.
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CD4+ T cells reactive against SARS-CoV-2 can be found in unexposed individuals, and these are suggested to arise in response to common cold coronavirus (CCCoV) infection. Here, we utilized ...SARS-CoV-2-reactive CD4+ T cell enrichment to examine the antigen avidity and clonality of these cells, as well as the relative contribution of CCCoV cross-reactivity. SARS-CoV-2-reactive CD4+ memory T cells were present in virtually all unexposed individuals examined, displaying low functional avidity and multiple, highly variable cross-reactivities that were not restricted to CCCoVs. SARS-CoV-2-reactive CD4+ T cells from COVID-19 patients lacked cross-reactivity to CCCoVs, irrespective of strong memory T cell responses against CCCoV in all donors analyzed. In severe but not mild COVID-19, SARS-CoV-2-specific T cells displayed low functional avidity and clonality, despite increased frequencies. Our findings identify low-avidity CD4+ T cell responses as a hallmark of severe COVID-19 and argue against a protective role for CCCoV-reactive T cells in SARS-CoV-2 infection.
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•Low avidity and broad cross-reactivities of pre-existing SARS-CoV-2 memory T cells•Strong CCCoV-specific memory CD4+ T cell responses in all analyzed individuals•SARS-CoV-2-specific CD4+ T cells in COVID-19 patients lack cross-reactivity to CCCoVs•Low avidity and clonality of SARS-CoV-2-specific T cell responses in severe COVID-19
Bacher et al. identify excessive but low-avidity T cell responses to SARS-CoV-2 as a hallmark of severe but not mild COVID-19. Pre-existing memory to SARS-CoV-2 in unexposed donors also displayed low avidity and harbored multiple, highly variable cross-reactivities that were not restricted to common cold coronaviruses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The reactivity of both coupling partners—the glycosyl donor and acceptor—is decisive for the outcome of a glycosylation reaction, in terms of both yield and stereoselectivity. Where the reactivity of ...glycosyl donors is well understood and can be controlled through manipulation of the functional/protecting‐group pattern, the reactivity of glycosyl acceptor alcohols is poorly understood. We here present an operationally simple system to gauge glycosyl acceptor reactivity, which employs two conformationally locked donors with stereoselectivity that critically depends on the reactivity of the nucleophile. A wide array of acceptors was screened and their structure–reactivity/stereoselectivity relationships established. By systematically varying the protecting groups, the reactivity of glycosyl acceptors can be adjusted to attain stereoselective cis‐glucosylations.
The sweet spot: An operationally simple system to gauge glycosyl acceptor reactivity is presented that employs two conformationally locked donors with stereoselectivity that critically depends on the reactivity of the acceptor. The structure–reactivity/stereoselectivity relationships of a wide array of acceptors were established. The reactivity of glycosyl acceptors can be adjusted by systematically varying the protecting groups to attain stereoselective cis‐glucosylations.
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Altered self-reported autonomic reactivity is associated with worse mental health in the general population. Although dysfunctional changes in ANS during pregnancy have been investigated in relation ...to depressive symptoms, no studies addressed the relationship between self-report autonomic reactivity during pregnancy and depressive symptoms after the delivery. The present study aimed to assess the impact of prepartum self-reported autonomic reactivity on the development of postpartum depressive symptoms.
In this longitudinal study, 170 women were assessed during pregnancy (i.e., second or third trimester) and after childbirth (i.e., one month after the delivery). Self-reported autonomic reactivity was assessed through the Body Perception Questionnaire – Short Form that evaluates the autonomic functions related to organs above (i.e., supradiaphragmatic reactivity) and below (i.e., subdiaphragmatic reactivity) the diaphragm. In addition, prepartum and postpartum depressive symptoms were evaluated using the Patient Health Questionnaire – 9.
Findings showed that higher prepartum supradiaphragmatic reactivity predicted higher depressive symptoms in the postpartum period (β = 0.112, p = 0.009) after controlling for prepartum depressive symptomatology and other potential covariates.
Evaluation of self-reported autonomic activity may be a useful tool to identify antenatally women at risk of postpartum depressive symptoms. Future studies are needed to evaluate the effectiveness of interventions aimed at reducing the threat-responsive autonomic reactivity at rest and improving adaptive autonomic regulation to prevent postpartum depression.
•Altered supradiaphragmatic reactivity predicts higher postpartum depressive symptoms.•Self-report autonomic reactivity might be a useful tool for depression screening.•Preventive intervention on autonomic reactivity may be implemented during pregnancy.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the current study, an effort is carried out to study the influence of pentanol as low reactive fuel (LRF) along with diesel and Thevetia peruviana methyl ester (TPME) as high reactive fuels (HRF) ...in reactivity controlled compression ignition (RCCI) engine. The experiments are conducted on dual fuel engine at 50% load for RCCI mode of operation by varying pentanol percentage in injected fuels. The results revealed that RCCI mode of operation at 10% of pentanol in injected fuels exhibited higher brake thermal efficiency (BTE) of 22.15% for diesel and pentanol fuel combination, which is about 9.1% and 27.3% higher than other B20 and pentanol, B100 and pentanol fuel combinations respectively. As the percentage of pentanol increased in injected fuels, hydrocarbon (HC) and carbon monoxide (CO) emissions are increased while nitrogen oxide (NOx) and smoke emissions are decreased. Among various fuel combinations tested diesel and pentanol fuel combination gives lower HC, CO and smoke emissions and higher NOx emissions. At 10% pentanol in injected fuels, the highest heat release rate (HRR) and in-cylinder pressure are found for diesel and pentanol fuel combinations compared with other fuels.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this work is to understand the characteristics of the pozzolanic reactivity of nanoSiO2 from studies of its pozzolanic reaction kinetics, morphology and structure of the hydrates and the ...influences of these features on the properties of cement-based materials, so as to explore a more targeted way of using nanoSiO2 in cement or concrete. It revealed that the pozzolanic reaction of nanoSiO2 is of the first-order and the apparent reaction rate constant of nanoSiO2-4nm is about one order of magnitude bigger than that of silica fume, but the specific reaction rate constant is about one half to that of silica fume. A compacter gel structure and poorer crystallinity of the hydrates of nanoSiO2 to those of silica fume are found, as well. The rate of hydration of cement at very early ages is enhanced by nanoSiO2, but the rate slows down with aging due to the compact gel structure. To make the use of the high pozzolanic reactivity and ultrafine particle size of nanoSiO2, as well as its resulting compact gel structure, colloidal nanoSiO2 was applied onto the hardened cement mortar by brushing technique and a less permeable surface was resulted, which shows the potential of using nanoSiO2 as a surface treatment material for cement-based materials.
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