Robust high-temperature potassium-ion batteries enabled by carboxyl functional group energy storage

The popularly reported energy storage mechanisms of potassium-ion batteries (PIBs) are based on alloy-, de-intercalation-, and conversion-type processes, which inevitably lead to structural damage of the electrodes caused by intercalation/de-intercalation of K+ with a relatively large radius, which is accompanied by poor cycle stabilities. Here, we report the exploration of robust high-temperature PIBs enabled by a carboxyl functional group energy storage mechanism, which is based on an example of p-phthalic acid (PTA) with two carboxyl functional groups as the redox centers. In such a case, the intercalation/de-intercalation of K+ can be performed via surface reactions with relieved volume change, thus favoring excellent cycle stability for PIBs against high temperatures. As proof of concept, at the fixed working temperature of 62.5 °C, the initial discharge and charge specific capacities of the PTA electrode are ∼660 and 165 mA⋅h⋅g−1, respectively, at a current density of 100 mA⋅g−1, with 86% specific capacity retention after 160 cycles. Meanwhile, it delivers 81.5% specific capacity retention after 390 cycles under a high current density of 500 mA⋅g−1. The cycle stabilities achieved under both low and high current densities are the best among those of high-temperature PIBs reported previously.

Bright Blue, Green, and Red Luminescence from Dye-Sensitized Core@Shell Upconversion Nanophosphors under 800 nm Near-Infrared Light

In this study, Li-based blue- and green-emitting core@shell (C@S) upconversion nanophosphors (UCNPs) and NaGdF4-based red-emitting C@S UCNPs were synthesized, and IR-808 dyes were conjugated with the C@S UCNPs to enhance upconversion (UC) luminescence. The surface of the as-synthesized C@S UCNPs, which was originally capped with oleic acid, was modified with BF4− to conjugate the IR-808 dye having a carboxyl functional group to the surface of the UCNPs. After the conjugation with IR-808 dyes, absorbance of the UCNPs was significantly increased. As a result, dye-sensitized blue (B)-, green (G)-, and red (R)-emitting UCNPs exhibited 87-fold, 10.8-fold, and 110-fold enhanced UC luminescence compared with B-, G-, and R-emitting Nd3+-doped C@S UCNPs under 800 nm near-infrared (NIR) light excitation, respectively. Consequently, dye-sensitized UCNPs exhibiting strong UC luminescence under 800 nm NIR light excitation have high applicability in a variety of biological applications.

Valorization of Oued Sebou Natural Sediments (Fez-Morocco Area) as Adsorbent of Methylene Blue Dye: Kinetic and Thermodynamic Study

The objective of this study is to evaluate the efficiency of methylene blue removal using Oued Sebou sediments as an adsorbent. The presence of carboxyl functional group demonstrated by infrared (IR) analysis of the sediment favorized the methylene blue (MB) adsorption. Sediment collected from Oued Sebou could remove the most MB molecules at pH 8. The Freundlich model described suitably the adsorption process. The experimental measured enthalpy (ΔH) and entropy (ΔS°) are 118.1 kJ mol−1 and 395.2 J mol−1 K−1, respectively, indicating that the reaction was endothermic with an increase of randomness at the solid/liquid interface during the adsorption. The kinetics of MB adsorption by sediment were adequately fitted to the pseudo-second-order model. Experimental results showed that the adsorption capacity of the methylene blue dye depends on the solution pH, the initial dye concentration, the adsorbent mass, the sediment particle diameter, and the temperature of the reaction medium. The removal efficiency of the MB molecules reaches 100% after 60 minutes under the optimum conditions.

Synthesis and Photoelectrical Properties of 3-(Diphenylamino)Carbazolyl-Functionalized DMABI Derivatives

A modular approach was used in the synthesis of the 3-(diphenylamino)carbazolyl- functionalized 2-(4-(dimethylamino)benzylidene)-1H-indene-1,3(2H)-dione (DMABI) derivatives. For this purpose, carboxyl functional group was introduced into the framework of DMABI molecule. Additionally, a regioselective method for substitution of carbonyl group of DMABI with dicyanomethylene group was investigated and verified using the heteronuclear multiple bond correlation NMR spectra. Steglich esterification method was used to connect the 3‑(diphenylamino)carbazolyl moiety via an unconjugated spacer. The UV-Vis absorption spectra and molecular energy level data were obtained for the evaluation of the synthesized compounds as donor materials in bulk-heterojunction solar cells.

Assessing the Conformational Equilibrium of Carboxylic Acid via QM and MD Studies on Acetic Acid

Accurate hydrogen placement in molecular modeling is crucial for studying the interactions and dynamics of biomolecular systems. It is difficult to locate hydrogen atoms from many experimental structural characterization approaches, such as due to the weak scattering of x-ray radiation. Hydrogen atoms are usually added and positioned <i>in silico</i> when preparing experimental structures for modeling and simulation. The carboxyl functional group is a prototypical example of a functional group that requires protonation during structure preparation. To our knowledge, when in their neutral form, carboxylic acids are typically protonated in the <i>syn</i> conformation by default in classical molecular modeling packages, with no consideration of alternative conformations, though we are not aware of any careful examination of this topic. Here, we investigate the general belief that carboxylic acids should always be protonated in the <i>syn</i> conformation. We calculate and compare the relative energetic stabilities of <i>syn</i> and <i>anti</i> acetic acid using <i>ab initio</i> quantum mechanical calculations and atomistic molecular dynamics simulations. We show that while the <i>syn</i> conformation is the preferred state, the <i>anti</i> state may in some cases also be present under normal NPT conditions in solution.

Assessing the Conformational Equilibrium of Carboxylic Acid via QM and MD Studies on Acetic Acid

Accurate hydrogen placement in molecular modeling is crucial for studying the interactions and dynamics of biomolecular systems. It is difficult to locate hydrogen atoms from many experimental structural characterization approaches, such as due to the weak scattering of x-ray radiation. Hydrogen atoms are usually added and positioned <i>in silico</i> when preparing experimental structures for modeling and simulation. The carboxyl functional group is a prototypical example of a functional group that requires protonation during structure preparation. To our knowledge, when in their neutral form, carboxylic acids are typically protonated in the <i>syn</i> conformation by default in classical molecular modeling packages, with no consideration of alternative conformations, though we are not aware of any careful examination of this topic. Here, we investigate the general belief that carboxylic acids should always be protonated in the <i>syn</i> conformation. We calculate and compare the relative energetic stabilities of <i>syn</i> and <i>anti</i> acetic acid using <i>ab initio</i> quantum mechanical calculations and atomistic molecular dynamics simulations. We show that while the <i>syn</i> conformation is the preferred state, the <i>anti</i> state may in some cases also be present under normal NPT conditions in solution.

Synthesis, Characterization and Alpha Glucosidase Inhibition activity of new Phthalimide Derivatives

Three of imide intermediate products were synthesized by reacting of phthalic anhydride with glycine (2a), and tetrachloro phthalic anhydride with glycine , (S)-2-[(tert-Butoxycarbonyl)amino]-3-aminopropionic acid ( 2b,c) respectively in dry toluene with azeotropic removal of water using Dean- stark apparatus then carboxyl functional group activated by refluxing with thionyl chloride, the resulted acid chloride (3a-c) were reacted with different amine (5-flourouracil, 4-chloroaniline, 4-bromoaniline, 2-amino thiazole, and pyrrolidine) (4a-e) , the resulted products consider as the end products (5a-j) while the compounds (5k-o) required further reaction to deprotect aliphatic amine this achieved by treating the compounds with TFA to remove tert-Butoxycarbonyl group (6a-e). The alpha glucosidase inhibitory activity of some synthesized compounds (5a, 5f, 6a) were tested by using -glucosidase from Saccharomyces cerevisiae, p-nitrophenol glucopyranoside (pNPG) used as substrate and acarbose used as standard. All these test compounds shows excellent inhibitory activity according to IC50 values which is ranging from (4.61-7.32).