Electronegativity Effects Research Articles

Computational insights into photo-induced behaviours for chalcogen doping 2-benzooxazol-2-yl-5-diethylamino-phenol derivatives

In view of the distinguished photochemical and photobiological characteristics of 2-Benzooxazol-2-yl-5-diethylamino-phenol (BYDP) and its derivatives, herein, we mainly focus on probing into excited-state behaviours of the three chalcogen element substituted BYDP derivatives (i.e. BYDP-O, BYDP-S and BYDP-Se). For these three different fluorophores, we detangle the effects of atomic electronegativity and charge recombination related to oxygen elements in excited-state intramolecular proton-transfer (ESIPT) processes. Because of the low potential energy barriers, we confirm that the ESIPT is controlled by atomic electronegativity. We sincerely hope our work could provide a theoretical reference for proving this novel mechanism of ESIPT experimentally.

Computational detangling chalcogen elements substitutions associated ESDPT mechanism for oxazolinyl-substituted hydroxyfluorene derivatives

In view of the distinguished photochemical and photobiological characteristics of oxazolinyl-substituted hydroxyfluorene and its derivatives, herein, we mainly focus on probing into excited state behaviors of the novel 9,9-dimethyl-3,6-dihydroxy-2,7-bis(4,5-dihydro-4,4-dimethyl-2-oxazolyl) fluorene (Oxa-OH) derivatives. In light of the significant effects resulting from substituting oxygen elements, three Oxa-OH derivatives (i.e., Oxa-OO, Oxa-SS and Oxa-SeSe fluorophores) are considered in this work. For these three different fluorophores, we detangle the effects of atomic electronegativity and charge recombination related to oxygen elements in excited state double proton transfer (ESDPT) processes. Because of the low potential energy barriers, we confirm the ESDPT happens by the sequential type. Based on heterosubstituted Oxa-OS and Oxa-OSe compounds, we further verify the chalcogen atomic-electronegativity-regulated stepwise ESDPT mechanism. We sincerely wish our work could provide a theoretical reference for proving this novel mechanism of ESDPT experimentally.

Constructing Angstrom‐Level Ion Pocket Array in 1D Channel Wall for Efficient Lithium Ion Sieving

AbstractThe rapid development of new energy industry is leading to the scarcity of lithium (Li) metal. Rational design of adsorbents for efficient separation of Li+ ion from aqueous media is pivotal to solve the recovery of this valuable resource. Current adsorbents generally suffer from the drawbacks in adsorption capacity, kinetics, and selectivity. Herein, a novel and ultra‐stable metal–organic framework is designed for Li+ separation. The dense oxygen atoms on the cambered wall of its 1D channel encircle to form angstrom‐level tetrahedral ion pockets array, acting as the dominant adsorption sites. This rational distribution of the array avoids the pore blockage caused by the pre‐adsorbed ions, thereby accelerating the diffusion of subsequent ions into the interior pore. Meanwhile, this tetrahedral pocket shows distinct electronegativity and strong chelation effect for Li+. Benefiting from these specifics, this adsorbent exhibits a record‐breaking adsorption capacity for Li+ (76.1 mg g−1) and short equilibrium time (30 min). Moreover, the selective adsorption of Li+ over Na+, K+, Ca2+, and Mg2+ is achieved due to the matched Li+ ion diameter with the pocket/channel sizes and lower energy barrier for dehydration. Thus, this work proposes a feasible strategy for the construction of novel MOFs for ions adsorption.

Electronegativity Effect on C-Halogen Bond Stretching in Alkyl Halides at Higher Education Level

Electronegativity is an intrinsic parameter of each chemical element that influences the response, chemical reactivity, polarity, as well as the attraction between molecules among other effects. In this sense, a didactic strategy was developed for teaching at the undergraduate level to determine the effect that electronegativity has on the vibration response of the C-Halogen bond in a molecule, through a practical experience that involved on the one hand the technique of infrared spectrophotometry and organic molecules with the presence of halogen atoms. The didactic strategy was applied to a group of students of the bachelor’s degree in industrial chemistry, which was divided into teams of 5 students who worked based on cooperative learning and with problem-based learning support, they were studying spectroscopy and who had previous knowledge of the infrared spectroscopy technique. After carrying out, the experiment and with the results obtained, the students were able to conclude that due to the strength and distance of the bond between halogen and carbon, the value of the wavenumber (cm-1) is modified, concluding that in shorter bonds a greater energy is required for it to be stretched and in longer and weaker bonds as in the case of Iodine these are stretched to a lower wavenumber. This allowed students to understand this phenomenon and the dependence of electronegativity, bond length, and bond strength on a specific response observed using infrared spectroscopy.

Tactfully regulating the ESIPT mechanism of novel benzazolyl-4-quinolones fluorophore by atomic electronegativity

The effects of atomic electronegativity (O, S and Se) on the excited state intramolecular proton transfer (ESIPT) behavior of fluorescent benzazolyl-4-quinolones derivatives have been investigated theoretically. Analysis of structure parameters and infrared vibrational spectra indicate that the intramolecular hydrogen bonds (O1H1⋯N1) are gradually strengthened in the first (S1) excited state as the atomic electronegativity diminishes (O → S → Se). The topological parameters, reduced density gradient (RDG) scatter plots and interaction region indicator (IRI) isosurface further confirm our results. The energy gap of molecular orbitals reflect that the less atomic electronegativity prompt greater excited state reactivity. In addition, the constructed potential energy curves (PECs) reveal that Se substituent has lower potential barrier (0.42 kcal/mol), which is more likely to accelerate the occurrence of ESIPT process. These results show that the atomic electronegativity helps to regulate the ESIPT process, which will pave the way for the design and synthesis of ESIPT-based fluorophores in future.

Electronegativity Effects on Conformational Stability Using Bent's Rule: From Simple Molecules to Acetylcholine

Hybridization and electronegativity are fundamental concepts in chemistry connected by Bent's rule. This rule explains many aspects of the structural chemistry and reactivity of organic and inorganic compounds. Over decades, the application of Bent's rule has expanded, demonstrating its wide-ranging utility in elucidating molecular stability due to the substitution of highly electronegative atoms. This study successfully leverages Bent's rule to explain conformational energy difference in acetylcholine case using density-functional calculations. We used butane (Group 2) and butanone (Group 3) families to model the head of ACh+ and substituted one of the carbons with highly electronegative atoms: B, C, N, and O. This enabled us to evaluate the effects of electronegativity, as well as the presence of carbonyl groups, on their conformational stability and s character. There were three highlighted results. First, our calculations result in the s character are consistent with Bent's rule. Second, the high conformational energy differences can be attributed to the changes of s character in C2–Z bond: linear in Group 2 and exponential in Group 3, indicating the strong contribution of the carbonyl group. Third, the key determining factor in ACh+ conformational stability is the carbonyl group, which also strongly contributes to the solute-solvent interactions. Therefore, our study can be further applied to other similar molecules, potentially leading to broader applications in chemistry, especially for understanding ACh+ stability for Alzheimer’s Disease treatment.

Roles of Impurity Levels in 3d Transition Metal-Doped Two-Dimensional Ga2O3.

Doping engineering is crucial for both fundamental science and emerging applications. While transition metal (TM) dopants exhibit considerable advantages in the tuning of magnetism and conductivity in bulk Ga2O3, investigations on TM-doped two-dimensional (2D) Ga2O3 are scarce, both theoretically and experimentally. In this study, the detailed variations in impurity levels within 3d TM-doped 2D Ga2O3 systems have been explored via first-principles calculations using the generalized gradient approximation (GGA) +U method. Our results show that the Co impurity tends to incorporate on the tetrahedral GaII site, while the other dopants favor square pyramidal GaI sites in 2D Ga2O3. Moreover, Sc3+, Ti4+, V4+, Cr3+, Mn3+, Fe3+, Co3+, Ni3+, Cu2+, and Zn2+ are the energetically favorable charge states. Importantly, a transition from n-type to p-type conductivity occurs at the threshold Cu element as determined by the defect formation energies and partial density of states (PDOS), which can be ascribed to the shift from electron doping to hole doping with respect to the increase in the atomic number in the 3d TM group. Moreover, the spin configurations in the presence of the square pyramidal and tetrahedral coordinated crystal field effects are investigated in detail, and a transition from high-spin to low-spin arrangement is observed. As the atomic number of the 3d TM dopant increases, the percentage contribution of O ions to the total magnetic moment significantly increases due to the electronegativity effect. Additionally, the formed 3d bands for most TM dopants are located near the Fermi level, which can be of significant benefit to the transformation of the absorbing region from ultraviolet to visible/infrared light. Our results provide theoretical guidance for designing 2D Ga2O3 towards optoelectronic and spintronic applications.

Effects of atomic electronegativity on the ESIPT process and photophysical properties of naphthalene derivatives

The effect of atomic electronegativity on the excited state intramolecular proton transfer (ESIPT) and photophysical properties of naphthalene derivatives containing DNHP, DPHP and DAHP have been researched through the density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The potential energy curve (PEC) calculated shows that DNHP, DPHP and DAHP can generate ESIPT process and the ESIPT rate increases with the decrease of atomic electronegativity. Subsequently, we further explain the influence of atomic electronegativity on the ESIPT mechanism and photophysical properties of these molecules by electron-hole analysis. Eventually, we sincerely hope that these studies can be helpful in their application.

Theoretical study of atomic electronegativity effects on the excited‐state behavior of fluorescent compounds of citrinin

AbstractThe present work focuses on the light‐induced behavior of citrinin derivatives in relation to atomic electronegativity. A detailed theoretical study on the photophysical properties and excited‐state behavior of fluorescent compounds of citrinin (Cit‐O, Cit‐S, and Cit‐Se, with different atomic electronegativity) has been conducted, and the effect of electronegativity on the proton transfer in this system has been explained. First, the relevant hydrogen bond parameters and infrared vibrational spectra of the optimized geometrical configurations have been insightfully investigated. It is elucidated that the hydrogen bond is strengthened after photoexcitation, and it provides a driving force for excited‐state intramolecular proton transfer (ESIPT). In addition, the frontier molecular orbitals were analyzed, and the intramolecular charge transfer process in all Cit systems, the phenomenon of charge redistribution, facilitates the ESIPT reaction. By constructing potential energy surfaces for different transfer paths, the atomic electronegativity impact on the ESIPT dynamical behavior of the Cit system was determined. This work clarifies the mechanism of the intramolecular proton transfer process in the excited state of citrinin molecules and complements the theoretical study of the atomic electronegativity‐regulated citrinin system, which provides a corresponding theoretical basis for the design and synthesis of new luminescence‐adjustable citrinin systems.

Computational Investigation about the Effects of Solvent Polarity and Chalcogen Element Electronegativity on ESIPT Behaviors for the Et2N-Substituted Flavonoid.

Inspired by the outstanding nature of flavonoid derivatives in the fields of chemistry and medicine, in this work we mainly focus on exploring the photo-induced properties of the novel Et2N-substituted flavonoid (ENF) fluorophore theoretically. Considering the potential photo-induced properties in different solvents and the chalcogen atomic electronegativity-associated photoexcitation, by time-dependent density functional theory (TDDFT) methods we primarily explore the intramolecular hydrogen bonding interactions and photo-induced charge redistribution behaviors. Via comparing geometrical data and the infrared (IR) spectral shifts-associated hydroxy moiety of ENF, we confirm that the intramolecular hydrogen bond O-H···O should be enhanced with facilitating an excited-state intramolecular proton-transfer (ESIPT) reaction. Particularly, the charge reorganization around hydrogen bonding moieties further reveals the tendency of ESIPT behavior. Combined with the construction of the potential energy surface and the search for reaction transition states, we finally confirmed the solvent-polarity-regulated behaviors as well as the chalcogen elements' electronegativity-dependent ESIPT mechanisms for the ENF fluorophore. We sincerely wish our work could accelerate the further development and applications of flavonoid derivatives.

Two-dimensional Si2C material exhibits efficient conductive properties and outstanding capacitance characteristics in Li/Na/K-ion batteries

To improve the performance of energy storage devices, research into anode materials is essential. This study explores the potential of two-dimensional (2D) materials, particularly silicon carbide (Si2C), to enhance the efficacy of lithium-ion batteries (LIBs), sodium-ion batteries (SIBs), and potassium-ion batteries (KIBs). Our first-principles calculations indicate that Si2C achieves storage capacities of 174.7 mAh g−1 for LIBs, 436.8 mAh g−1 for SIBs, and 349.4 mAh g−1 for KIBs. The exceptional performance of Si2C comes from its high conductivity, large surface area, high capacitance, synergistic atomic radius and electronegativity effects. Furthermore, this study delves into the diffusion kinetics of Li/Na/K-ions in Si2C, revealing extremely low energy barriers and uncovering the fundamental principles behind its superior electrochemical performance. This research emphasizes Si2C’s potential in energy storage, highlighting its capacity and diffusion advantages for Li/Na/K-ion batteries.

Diselenide-Bridged Doxorubicin Dimeric Prodrug: Synthesis and Redox-Triggered Drug Release.

The diselenide bond has attracted intense interest in redox-responsive drug delivery systems (DDSs) in tumor chemotherapy, due to its higher sensitivity than the most investigated bond, namely the disulfide bond. Here, a diselenide-bridged doxorubicin dimeric prodrug (D-DOXSeSe) was designed by coupling two doxorubicin molecules with a diselenodiacetic acid (DSeDAA) molecule via α-amidation, as a redox-triggered drug self-delivery system (DSDS) for tumor-specific chemotherapy. The drug release profiles indicated that the D-DOXSeSe could be cleaved to release the derivatives selenol (DOX-SeH) and seleninic acid (DOX-SeOOH) with the triggering of high GSH and H2O2, respectively, indicating the double-edged sword effect of the lower electronegativity of the selenide atom. The resultant solubility-controlled slow drug release performance makes it a promising candidate as a long-acting DSDS in future tumor chemotherapy. Moreover, the interaction between the conjugations in the design of self-immolation traceless linkers was also proposed for the first time as another key factor for a desired precise tumor-specific chemotherapy, besides the conjugations themselves.

An innovative method for predicting oxidation reaction rate constants by extracting vital information of organic contaminants (OCs) based on diverse molecular representations

The reaction rate constant (k) of oxidants with organic contaminants (OCs) is an important parameter to assess the efficiency of oxidants in removing contaminants. In this study, the degradation of OCs in three oxidation systems was evaluated. The modeling process applied three molecule representations (molecular descriptors (MD), quantum chemical descriptors (QCD) and MACCS fingerprints) and their variable integrations. Models based on integration molecule representations show significant performance improvements. Eventually, the optimal models for ozone, chlorine dioxide and hypochlorite were found to be (MD+QCD)-XGBoost (R2tra = 0.982, Q2tra = 0.715), (MD+QCD+MACCS)-XGBoost (R2tra = 0.982, Q2tra = 0.778), and (MD+QCD+MACCS)-CatBoost (R2tra = 0.856, Q2tra = 0.709) model, respectively. Here, we introduced a new perspective that differed from focusing on machine learning (ML) algorithm optimization. This perspective centered on the input variables (i.e., molecular representations) of models to improve model performance by capturing the key properties of OCs comprehensively. Furthermore, the key effects of pH, ionization potential, orbital energy, polarizability and electronegativity on the oxidation reaction in different oxidation systems were clarified. We hope that the mechanism explanation in this study can provide valuable insights for understanding the mechanism of various oxidation reactions of complex OCs.

Nitric Acid‐Mediated Artificial Urea Photo‐Synthesis With N2 And CO2

AbstractPhotocatalytic urea synthesis, utilizing N2 and CO2 as feedstock and sustainable solar energy, represents an environmentally friendly and promising alternative strategy. However, the conventional unidirectional gas phase co‐reduction techniques typically employes pose stringent demands for the design of key catalysts, reaction control, mass transfer, and other aspects, due to the disparity in physical properties, structure, and catalytic kinetics between N2 and CO2. Herein, Ru‐TiO2 is synthesized and employed as an effective catalyst for urea photo‐synthesis through a nitric acid‐mediated pathway combining nitrogen oxidation and subsequent kinetically advantageous nitrate and CO2 co‐reduction. A urea yield of 24.95 µmol h−1 g−1cat. is obtained through an innovative intermittent illumination method, AQE values of 4.7% and 6.3% at 380 and 420 nm, respectively. The remarkable photo‐activity is attributed to its unique oxygen vacancy‐anchored Ru nanostructure (Ru‐O4Ti1), which effectively activates inert N2 molecules to minish the disparity of orbital energy levels, facilitates the formation of crucial *NN(OH) intermediates, and serves as an “electronic pump” to avoid electronegativity effect for facilitating electron transfer from nitrogen to TiO2 support for urea photosynthesis. This study presents groundbreaking insights for nitrogen oxidation activation and provides brand‐new ideas for the direct resource utilization of nitrogen.

Theoretical exploring effects of solvent polarity and atomic electronegativity on excited state behaviour for BY4TP fluorophore

As widely acknowledged, the realm of novel organic molecules boasting extraordinary attributes pertaining to excited-state intramolecular proton transfer (ESIPT) has emerged as a captivating subject matter. In this context, our primary focus lies in delving into the excited-state behaviour exhibited by 2-benzoxazol-2-yl-4-triethylsilanylethynyl-phenol (BY4TP), an alluring derivative derived from 2-(2-hydroxyphenyl)benzoxazole (HBO). Relying on the examination of four distinct aprotic solvents with varying degrees of polarities, we can unequivocally affirm that solvent polarity exerts a profound influence on the intricate interplay of hydrogen bonding interactions, charge redistribution and reorganisation, as well as associated ESIPT phenomena by light. Through meticulous comparison and precise measurement of reaction barriers across diverse solvent environments, our groundbreaking findings indicate that lowly polar solvents serve as efficacious facilitators for promoting the occurrence of the ESIPT reaction in BY4TP fluorophore. By considering atomic-electronegativity-regulated hydrogen bonding effects and excited state behaviours for BY4TP-S and BY4TP-Se, we also present low atomic electronegativity with Se substation promotes ESIPT reaction. We ardently anticipate that this study will provide invaluable insights into the behaviour exhibited by BY4TP upon excitation and under the influence of solvent polarity and atomic electronegativity, while simultaneously paving new avenues for future research endeavours and applications encompassing novel HBO derivatives.

Effects of radius and electronegativity of donors on the microstructure and mechanical, thermal, and electrical properties of ZnO varistors

Effects of radius and electronegativity of donors on the microstructure and mechanical, thermal, and electrical properties of ZnO varistors

Effects of atomic electronegativity of halogen on excited state reactional behaviors for 4-chloro-2-[1-(4-methoxy-phenyl)-4,5-diphenyl-1H-imidazol-2-yl]-phenol compound: a theoretical study

Effects of atomic electronegativity of halogen on excited state reactional behaviors for 4-chloro-2-[1-(4-methoxy-phenyl)-4,5-diphenyl-1H-imidazol-2-yl]-phenol compound: a theoretical study

Electron, hole and radical competition mechanism of layered porous g-C3N4 for hydrogen generation and organic pollutant degradation

Halogen doping is an effective approach to regulate the electronic structure and improve photocatalytic properties of g-C3N4. Here, a salt-assisted approach was employed to prepare layered porous halogen-doped g-C3N4. The effects of halogen electronegativity and pore morphology were discussed. Highly electronegative F-doped g-C3N4 with smaller pore size and higher surface area displayed the enhanced absorption property on reactants. The H2 production rate decreased and the RhB degradation significantly increased with increasing the electronegativity of layered porous g-C3N4, which was significantly different from the conventional halogen-doped g-C3N4 prepared with halogenated acid and monolayer g-C3N4. The decreased H2 evolution can be ascribed to the strong adsorption property, and the strong interactions between halide ions and H+ were difficult to be disassociated. Additionally, the RhB degradation performance of halogen-doped g-C3N4 significantly increased with increasing the electronegativity. The most active species that dominated the RhB degradation of F-doped g-C3N4 are leaved holes (h+), which are totally different from that of the pristine g-C3N4 and Cl/Br-doped g-C3N4 (superoxide radicals,·O2–). This work helps us to well understand the role and importance of electronegativity and pore morphology on the H2 generation and RhB degradation properties of layered porous g-C3N4.

DFT/TDDFT based study to decipher the excited state intramolecular proton transfer process for 3-benzothiazol-2-yl-2-hydroxy-5-methyl-benzaldehyde-oxime

In this study, we theoretically investigate the interactions of hydrogen bonding in excited states and the mechanism of intramolecular proton transfer (ESIPT) for the novel compound 3-benzothiazol-2-yl-2-hydroxy-5-methyl-benzaldehyde-oxime (HBT-phos) theoretically. Herein, the effects of atomic electronegativity of chalcogen (O, S and Se) are also focused. Firstly, employing quantum theory of atoms-in-molecules (QTAIM) method, we confirm intrinsic quality of O-H···N within HBT-phos derivatives (HBT-phos-O, HBT-phos-S and HBT-phos-Se). By astutely examining changes in geometries and infrared (IR) spectra, we elegantly demonstrate O-H···N is remarkably strengthened in S1 state, indicating a pronounced tendency towards ESIPT. Computational hydrogen bonding energies further magnificently support this conclusion. Probing into photo-induced excitation, we discover heightened electronic densities surrounding N atom that play pivotal roles in attracting protons, thereby facilitating ESIPT. Ultimately, upon comparing potential energy curves in excited states, we deduce ESIPT process is expected to be exceptionally rapid with low atomic electronegativity (O → S → Se), which elucidates why detecting fluorescence peak of HBT-phos-S itself proves challenging in experiment. This study not only fills the void in understanding ESIPT mechanism within HBT-phos derivatives and authentically reveals its unambiguous mechanism, but also presents atomic-electronegativity-dependent ESIPT behaviour and the explanation for fluorescence quenching observed in prior experiment.

Theoretical investigation into the effect of atomic electronegativity related chalcogen on ESIPT behaviour for the novel biphenyl-modified 2-(2’-hydroxyphenyl)benzothiazole compounds

Inspired by the remarkable photochemical and photophysical properties of novel 2-(2’-hydroxyphenyl)benzothiazole (HBT) derivatives that could be potentially applied across various disciplines, in this work, effects of atomic electronegativity of chalcogen elements on excited state hydrogen bond effects and excited state intramolecular proton transfer (ESIPT) reaction of the biphenyl-modified HBT derivatives (i.e. HBT-HH-O, HBT-HH-S and HBT-HH-Se) are focused. By comparing the structural changes and infrared (IR) vibrational spectra of the HBT-HH fluorophores in toluene solvent, combined with the preliminary detection of hydrogen bond interaction by core-valence bifurcation (CVB) index, we can conclude that the hydrogen bond could be strengthened in S1 state, which is favourable for the occurrence of ESIPT reactions. The charge recombination behaviour of hydrogen bond induced by photoexcitation also further illustrates this point. Via constructing potential energy curves (PECs) based on restrictive optimisation and searching transition state (TS) form, we confirm the variations of atomic electronegativity of chalcogen have the regulatory effect on the ESIPT behaviour for HBT-HH derivatives, that is, the lower the atomic electronegativity is more conducive to the ESIPT reaction.