Density Functional Theory Computational Studies Research Articles

Enhanced Activity and Selectivity for Nitrogen Reduction Reaction in Electrode-based Heterostructures: A DFT Computational Study.

Developing sustainable and efficient catalysts for ammonia synthesis from atmospheric molecular N2 under ambient conditions presents a significant 21st-century challenge. Two-dimensional heterostructures, particularly single-atom catalysts (SACs) supported on two-dimensional materials, have emerged as a promising avenue due to their remarkable catalytic activity and selectivity. Electrides, characterized by an abundance of free electrons and high surface activity, have attracted substantial attention in this context. Through density functional theory (DFT) calculations, this study proposes electride-graphene heterostructures (EGHS) as catalysts to effectively regulate charge distribution at the catalytic center, facilitating the optimization of catalytic performance. The EGHS model addresses challenges related to excessive adsorbate binding, mitigating electron transfer compared to electride monolayer adsorption. This novel approach utilizes heterogeneous heterostructures to finely tune the catalytic site, optimizing electron input for enhanced catalysis.Based on the optimized charge transfer for N2 activation, the Cr-doped EGHS (Cr@EGHS) exhibits a promising performance in the nitrogen reduction reaction, leading to, a relatively low limiting potential of -0.85 V and high selectivity. The hypothesis charge transfer depend on N2 activation is further supported by modulating the distance between component layers of heterostructure. These findings contribute to design principles for 2D heterostructure catalysts and offer a reference for experimental synthesis.

Electro/Ni Dual‐Catalyzed Decarboxylative C(sp3)−C(sp2) Cross‐Coupling Reactions of Carboxylates and Aryl Bromide

AbstractPaired redox‐neutral electrolysis offers an attractive green platform for organic synthesis by avoiding sacrificial oxidants and reductants. Carboxylates are non‐toxic, stable, inexpensive, and widely available, making them ideal nucleophiles for C−C cross‐coupling reactions. Here, we report the electro/Ni dual‐catalyzed redox‐neutral decarboxylative C(sp3)−C(sp2) cross‐coupling reactions of pristine carboxylates with aryl bromides. At a cathode, a NiII(Ar)(Br) intermediate is formed through the activation of Ar−Br bond by a NiI‐bipyridine catalyst and subsequent reduction. At an anode, the carboxylates, including amino acid, benzyl carboxylic acid, and 2‐phenoxy propionic acid, undergo oxidative decarboxylation to form carbon‐based free radicals. The combination of NiII(Ar)(Br) intermediate and carbon radical results in the formation of C(sp3)−C(sp2) cross‐coupling products. The adaptation of this electrosynthesis method to flow synthesis and valuable molecule synthesis was demonstrated. The reaction mechanism was systematically studied through electrochemical voltammetry and density functional theory (DFT) computational studies. The relationships between the electrochemical properties of carboxylates and the reaction selectivity were revealed. The electro/Ni dual‐catalyzed cross‐coupling reactions described herein expand the chemical space of paired electrochemical C(sp3)−C(sp2) cross‐coupling and represent a promising method for the construction of the C(sp3)−C(sp2) bonds because of the ubiquitous carboxylate nucleophiles and the innate scalability and flexibility of electrochemical flow‐synthesis technology.

Leveraging Nonstrained C-C Bonds for Selective Carboacylation of an Unactivated Alkyne via Transient Dearomatization.

Carboacylation of an unsaturated bond represents a powerful transformation. However, only a few examples of carboacylation of alkyne have been reported through C-C bond scission and reconnection. Here, we report a method of carboacylation of an unactivated alkyne by utilizing nonstrained C-C bonds under gold(I) catalysis. The density functional theory computational and experimental studies reveal that the reaction proceeds through a C-to-C formal 1,3-acyl migration via a solvent cage-nested acylium cation.

Electro/Ni Dual-Catalyzed Decarboxylative C(sp3)-C(sp2) Cross-Coupling Reactions of Carboxylates and Aryl Bromide.

Paired redox-neutral electrolysis offers an attractive green platform for organic synthesis by avoiding sacrificial oxidants and reductants. Carboxylates are non-toxic, stable, inexpensive, and widely available, making them ideal nucleophiles for C-C cross-coupling reactions. Here, we report the electro/Ni dual-catalyzed redox-neutral decarboxylative C(sp3)-C(sp2) cross-coupling reactions of pristine carboxylates with aryl bromides. At a cathode, a NiII(Ar)(Br) intermediate is formed through the activation of Ar-Br bond by a NiI-bipyridine catalyst and subsequent reduction. At an anode, the carboxylates, including amino acid, benzyl carboxylic acid, and 2-phenoxy propionic acid, undergo oxidative decarboxylation to form carbon-based free radicals. The combination of NiII(Ar)(Br) intermediate and carbon radical results in the formation of C(sp3)-C(sp2) cross-coupling products. The adaptation of this electrosynthesis method to flow synthesis and valuable molecule synthesis was demonstrated. The reaction mechanism was systematically studied through electrochemical voltammetry and density functional theory (DFT) computational studies. The relationships between the electrochemical properties of carboxylates and the reaction selectivity were revealed. The electro/Ni dual-catalyzed cross-coupling reactions described herein expand the chemical space of paired electrochemical C(sp3)-C(sp2) cross-coupling and represent a promising method for the construction of the C(sp3)-C(sp2) bonds because of the ubiquitous carboxylate nucleophiles and the innate scalability and flexibility of electrochemical flow-synthesis technology.

Improved cycle stability and high-rate capability of LiNbO3-coated Li3VO4 as anode material for lithium-ion battery

Lithium vanadate (Li3VO4) has garnered considerable attention as an alternative negative electrode material for non-aqueous lithium-ion batteries due to its high capacity, energy efficiency, and stable discharge voltage. Nonetheless, the Li3VO4 material displays a low rate capability, attributed mainly to its poor intrinsic electronic conductivity. Here, we report the synthesis of lithium niobate LiNbO3-coated Li3VO4 (LVO@LNO) using a one-pot sol-gel method. The resulting LVO@LNO demonstrates a high reversible capacity of approximately 530 mAh/g, which is more than double that of free Li3VO4. To explore the effect of the LNO coating process on the morphological and structural properties, Raman, XRD, operando XRD, XPS, SEM and HTEM analyses were conducted. To explain the enhancement of electronic conductivity in our modified material after a LiNbO3 coating, we conducted an Ex-Situ electrochemical impedance (EIS) and Density Functional Theory (DFT) computational study. Additionally, we designed a full cell utilizing a 1 wt% LNO-coated LVO anode and NMC-811 cathode. The cell yielded an output voltage of approximately 2.8 V with a high initial specific capacity of 350 mAh/g versus to the anode, at 1C with a capacity retention of 85 % after 100 cycles.

Investigations of swift heavy ion induced thermoluminescence effect, trapping parameter analysis, and density functional theory of MgB4O7: Eu phosphor

The present work reports swift heavy ion (SHI) induced thermoluminescence (TL) dosimetric properties and density functional theory (DFT) studies of Eu doped MgB4O7 phosphor. Comparative investigations of structural, and luminescent properties of MgB4O7:Eu phosphor upon irradiation by 100 MeV Ag7+ and Ni7+ ion beams at the varied fluence range from 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2 are presented systematically. Eu doped MgB4O7 phosphor is prepared by facile hydrothermal method. X-ray diffraction pattern of the material reveals its orthorhombic structure with crystallite size of ∼30 nm. Fourier transform infrared spectroscopy (FTIR) studies demonstrate loss of crystallinity of material after the SHI irradiations. Correlation of stopping powers and projectile range calculations is performed using SRIM software. The investigated photoluminescence properties show emission bands located in the orange-red region with prominent peaks centered at ∼593 nm and ∼625 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ion. The influence of ion beam fluence on the photoluminescence properties has been explored. Variation in the intensity of the PL peaks without any shift in the peak positions is observed at different ion fluence. The TL glow curve of phosphor exhibits two major dosimetric peaks (a) at 185 °C and 275 °C and (b) at 172 °C and 273 °C upon Ag7+ and Ni7+ ion beam irradiation respectively. The phosphor shows fairly good linear dose response in the range of 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2. Fading measurements reveal 10% and 12% fading for the irradiation of Ag7+ and Ni7+ ions respectively in two months. Trapping parameter calculations of SHI irradiated phosphors are carried out via various TL glow curve analysis methods such as, peak shape method, whole glow peak method, and glow curve deconvolution method. Efficient thermoluminescence properties of MgB4O7:Eu make it a potential phosphor material and promise to provide avenue into swift heavy ion dosimetry applications. DFT computational studies performed to obtain the electronic structure of Eu doped MgB4O7 phosphor support the experimental results of crystal structure, symmetry and electronic structure studies.

Reusable HNO Sensors Derived from Cu Cyclam: A DFT Study on the Mechanistic Origin of High Reactivity and Favorable Conformation Changes and Potential Improvements.

Nitroxyl (HNO) exhibits unique favorable properties in regulating biological and pharmacological activities. However, currently, there is only one Cu-based HNO sensor that can be recycled for reusable detection, which is a Cu cyclam derivative with a mixed thia/aza ligand. To elucidate the missing mechanistic origin of its high HNO reactivity and subsequent favorable conformation change toward a stable CuI product that is critical to be oxidized back by the physiological O2 level for HNO detection again, a density functional theory (DFT) computational study was performed. It not only reproduced experimental structural and reaction properties but also, more importantly, revealed an unknown role of the coordination atom in high reactivity. Its conformation change mechanism was found to not follow the previously proposed one but involve a novel favorable rotation pathway. Several newly designed complexes incorporating beneficial effects of coordination atoms and substituents to further enhance HNO reactivity while maintaining or even improving favorable conformation changes for reusable HNO detection were computationally validated. These novel results will facilitate the future development of reusable HNO sensors for true spatiotemporal resolution and repeated detection.

Support Effect of Boron Nitride on the First N-H Bond Activation of NH3 on Ru Clusters.

Support effect is an important issue in heterogeneous catalysis, while the explicit role of a catalytic support is often unclear for catalytic reactions. A systematic density functional theory computational study is reported in this paper to elucidate the effect of a model boron nitride (BN) support on the first N-H bond activation step of NH3 on Run (n = 1, 2, 3) metal clusters. Geometry optimizations and energy calculations were carried out using density functional theory (DFT) calculation for intermediates and transition states from the starting materials undergoing the N-H activation process. The primary findings are summarized as follows. The involvement of the model BN support does not significantly alter the equilibrium structure of intermediates and transition states in the most favorable pathway (MFP). Moreover, the involvement of BN support decreases the free energy of activation, ΔG≠, thus improving the reaction rate constant. This improvement is more obvious at high temperatures like 673 K than low temperatures like 298 K. The BN support effect leading to the ΔG≠ decrease is most significant for the single Ru atom case among all three cases studied. Finally, the involvement of the model BN may change the spin transition behavior of the reaction system during the N-H bond activation process. All these findings provide a deeper insight into the support effect on the N-H bond activation of NH3 for the supported Ru catalyst in particular and for supported transition metal catalysts in general.

Acetoxy Group-Directed Regioselective C2 Alkenylation of Indoles via Pd-Ag Bimetallic Catalysis.

Regioselective C-H functionalizations of indoles reported to date with directing groups at C3 mainly rely on functional groups that are linked to the indole via C-C bonds. However, groups that are linked to the indole core by C-X linkages are also attractive due to the possibility of further modifications of the C-X bond. Herein, we report a 3-acetoxy directing group for the regioselective C2 alkenylation of indoles via a C-H activation-based, cross-dehydrogenative, oxidative Heck-type reaction. The reaction is catalyzed by Pd(II) and Ag(I) with stoichiometric Cu(II) as the oxidant and provides the 2-alkenylated indoles in yields of 52-84%. The reaction conditions are compatible with several functional groups at different positions as well as different N-protecting groups or free NH groups on the indole core. With respect to the alkene coupling partners, the reactions are successful with acrylates, vinyl sulfates, and phosphates. Specifically designed experiments, as well as density functional theory (DFT) computational studies, reveal that a heterodinuclear [Pd(μ-OAc)3Ag] bimetallic species is the actual catalyst responsible for the C-H alkenylation. A mechanistic path involving this catalytic species was also found to be favorable over other possible pathways for explaining the observed regioselectivity through DFT studies.

Enhanced production and control of liquid alkanes in the hydrogenolysis of polypropylene over shaped Ru/CeO2 catalysts

The hydrogenolysis of polypropylene waste to liquid hydrocarbons offers a promising pathway for the chemical recycling of waste polymers. This work describes the importance of reaction conditions and support morphology to produce high liquid yields with enhanced control of chain length over highly active shaped and non-shaped Ru/CeO2 catalysts. The shaped 2 wt% Ru/CeO2 exhibit high liquid alkane yields (58–81%) when compared to the non-shaped 2 wt% Ru/CeO2 (liquid yield: 34–58%) under optimized reaction conditions (220 °C, 16 h, 30 bar H2). In particular, the 2 wt% Ru/CeO2 nanocube catalyst exhibits the highest activity yielding lighter hydrocarbons. This was rationalized to be a combination of small Ru cluster formation and enhanced metal-support interactions. The influence of larger Ru particles (≥1.5 nm) was confirmed mechanistically using a computational density functional theory study on the hydrogenolysis of pentane (C5) to determine the favorable formation of methane in the non-shaped Ru/CeO2 catalyst.

Ab-initio and density functional theory (DFT) computational study of the effect of fluorine on the electronic, optical, thermodynamic, hole and electron transport properties of the circumanthracene molecule

In this paper, a systematic study of the electronic, optical, thermodynamic, optoelectronic, and nonlinear optical properties with RHF, B3LYP, wB97XD and BPBE methods using the cc-pVDZ basis set have been described to investigate the influence of fluorine (F) atom, which is an electron donor, on the circumanthracene (C40H16). Global reactivity descriptors, hole and electron transport properties were also calculated and compared with other studies on the same molecule. DFT/B3LYP results show that the undoped C40H16 molecule (Egap = 2.135 eV) and its fluorine-doped derivatives (C40F16 and C40H10F6) are semiconducting materials. However, doping the C40H16 molecule with the fluorine atom, partially or totally, favors the creation of a strong donor-acceptor system by considerably reducing its energy gap (Egap). The energy gap values of molecules doped using DFT/B3LYP method are 2.020 eV and 2.081 eV for the C40F16 and C40H10F6 molecules, respectively. These gap energies are below 3 eV, which favours the electronic properties of these molecules. They can be used to design organic solar cells. The nonlinear optical parameters were calculated and compared with those of urea. The values of βmol and μ calculated for C40F16 and C40H10F6 are higher than those of urea; this shows that these two materials have good nonlinear optical properties and therefore, are very good candidates for the design of optoelectronics and photonics devices. Futhermore, our results show that the perfluorination effect on the circumanthracene molecule increases the hole and electron reorganization energies, the vertical and adiabatic electron affinities and ionization energies, the optoelectronic and nonlinear optical properties, the transition excitation energy and the reactivity indices. The reorganization energies values suggest that these materials have promising transport properties. The natural bond orbital (NBO) analysis was also performed to determine the stability energy and charge delocalization in molecules. The theoretical results of the compounds studied in our work are in agreement with the experimental results. This confirms their molecular structures.

Cg…Cg interactions driven 1D polymeric chains bridged by lattice solvents in N3-(2-pyridoyl)-4-pyridinecarboxamidrazone Pb(II) complex

This study will shed light on the non-covalent interactions present in the N3-(2-pyridoyl)-4-pyridinecarboxamidrazone Pb(II) complex [(L)Pb(CH3OH)(H2O)2] and their significance in the context of crystal packing and material properties. The complex was synthesized and characterized using single crystal X-ray structural analysis, providing valuable insights into its molecular structure. Our focus was on analyzing the non-covalent interactions in the crystal structure, where these interactions played a crucial role in the formation of one-dimensional network chains observed in the crystal. To quantitatively analyze these interactions, we employed Hirshfeld surfaces analysis. Furthermore, we performed density functional theory computational studies to calculate the molecular geometry and global reactive parameters, allowing us to gain a better understanding of the properties of the novel molecule. The molecular electrostatic potential was plotted to visualize the charge distribution and identify the electrophilic and nucleophilic sites in the molecule. Finally, we explored the non-covalent interactions and electron charge density distribution using the QTAM and NCI models, providing further insights into the complex's behavior. This study contributes to the understanding of non-covalent interactions in the context of crystal growth and design, and expands the knowledge of the structural and electronic properties of the N3-(2-pyridoyl)-4-pyridinecarboxamidrazone Pb(II) complex.

Crystal structure, Hirshfeld surface analysis, and DFT calculation of 2-pyrazoline-4-ols

DFT computational study at B3LYP/6−31++G** level of theory and single crystal structure analysis of three crystallized 2-pyrazoline-4-ols (DHPZ-OH) were carried out to compare the differences in the structural orientation, electronic and bonding characteristics in both investigations. X-ray crystallography showed that compounds 1, 2, and 3 are crystallized in monoclinic, monoclinic, and triclinic systems, with the space group P21/c, P21/n, and P-1, respectively. Owing to the presence of two neighboring stereocenters, these crystal structures represent the enantiomeric pairs in the crystal packing. Hirshfeld surface analysis (HS) showed that both conventional donor (D)/acceptor (A)-interactions, such as D-H‧‧‧‧‧A, H‧‧‧‧‧N2 and D‧‧‧‧‧O interactions between the appropriate positions in the molecules. Also, the donor/acceptor interaction between the aromatic rings (π-π stacking) ensured the stabilization and orientation of the molecules in the crystal packing. The computational results concerning the geometrical parameters such as the bond lengths, bond torsion, and bond angles were compared with the crystal data. The energies of the HOMO and the LUMO orbitals, and the molecular electrostatic potential (MEP) were generated using the density functional theory (DFT). The MEP map showed the areas of the negative potential region around the electronegative atoms O24 and N2, while the maximum positive sites were around the hydrogen atom attached to O24.

Removal of enalapril maleate drug from industry waters using activated biochar prepared from Butia capitata seed. Kinetics, equilibrium, thermodynamic, and DFT calculations

Porous biochar was fabricated from Butia capitata (Bc) seed, which was used to uptake enalapril maleate from synthetic wastewater. Activated biochars were fabricated by blending Bc and ZnCl2 at 1:1 (BcB-1.0) or 1:1.5 (BcB-1.5) proportions and furtherly pyrolyzed at 600 °C. The elemental analysis, Boehm titration, hydrophobic balance ratio, FTIR, TGA, and N2 isotherm characterized the carbon-based materials. They presented a hydrophilic behavior with diverse polar groups on their surface. BcB-1 and BcB-1.5 biochars have a total pore volume of 0.392 and 0.492 cm3 g−1 and a surface area of 1267 and 1520 m2/g, respectively. The kinetics and isothermal data were adequately adjusted to the fractal-like pseudo-second-order and Liu models. The employment of BcB-1.0 and BcB-1.5 for treating synthetic wastewater containing high levels of pollutants had elevated efficiency in their removals (up to 99.06%). We also conducted a DFT computational study, density functional theory (DFT), to examine the interactions between enalapril and a graphitic domain of biochar by using these calculations, the most stable configuration presented interaction energy of −88.7 kJ mol−1 implies a face-to-face π–π stacking interaction involving the enalapril phenyl segment and an aromatic ring of the graphitic domain, as well as London dispersion arising from the proximity of ethoxy/pyrrolidine to biochar carbon atoms, with interatomic distances of 3.31 Å for the former and 3.60 Å /3.48 Å for the latter. Also, the DFT calculations agreed with the thermodynamic data calculated from the isotherms (283–318 K).

A neutral rhenium–biimidazole complex for the selective recognition of fluoride ions

The neutral rhenium(I)-biimidazole complex [Re(CO)3(biimH)(1,4-NVP)] (1) was designed and synthesized by a one-pot reaction of Re2(CO)10, 2,2′-biimidazole (biimH2) and 4-(1-naphthylvinyl)pyridine (1,4-NVP). The structure of 1 was characterized by various spectroscopic techniques including IR, 1H NMR, FAB-MS, and elemental analysis and further confirmed by a single-crystal X-ray diffraction analysis. The mononuclear complex 1, a relatively simple structure with an octahedral geometry, is comprised of facial-arranged carbonyl groups, one chelated biimH monoanion, and one 1,4-NVP. Complex 1 shows the lowest energy absorption band at around 357 nm and an emission band at 408 nm in THF. The luminescent characteristics of 1 combined with the hydrogen bonding ability of the partially coordinated monoionic biimidazole ligand permits the complex to selectively recognize fluoride ions (F–) in the presence of other halides through a dramatic luminescence enhancement. The recognition mechanism of 1 can be convincingly explained in terms of H-bond formation and proton abstraction upon the addition of F– ions by 1H and 19F NMR titration experiments. The electronic properties of 1 were further supported by time dependent density functional theory (TDDFT) computational studies.

UV protective textile: Experimental and DFT computational studies on the function of some metal complexes of hydrazide derivatives on cellulose fabrics

Ultraviolet (UV) radiation is harmful to the skin. Therefore, it capitalized on the properties of thiophene and pyridine derivatives to prepare new textile‐protective agents with improved UV protection factor (UPF) factor. This embodies the preparation and characterization of “2‐((3‐cyano‐4‐(4‐methoxyphenyl)‐6‐(thiophene‐2‐yl)pyridine‐2‐yl)oxy)acetohydrazide” (HZ) in complex with Ni(II), Cu(II), Zn(II), or Cd(II), using proton nuclear magnetic resonance (1H NMR), carbon‐13 nuclear magnetic resonance (13C NMR), X‐ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), and thermal analysis techniques. Characterization of cotton fabric‐based cellulose (CELL) in complex with the synthesized agents using FTIR spectroscopy, X‐ray spectroscopy, and scanning electron microscopy–energy dispersive X‐ray analysis (SEM–EDX) revealed deposition of the hydrazide and its metal complexes on the cellulosic fiber. Interestingly, cellulose complexation with Cu(II) was observed to have the highest value of the UPF. Computation of the reactivity indices using density functional theory (DFT) supports this finding, where the electrophilicity parameter of the modified fabric was found to correlate with the UPF wherein Cu(II) shows the highest value. The synthesized complexes could, therefore, provide lead structures for developing new UV‐protective agents with enhanced coating characteristics.

Ionothermally Synthesized Nanoporous Ti0.95W0.05Nb2O7: a Novel Anode Material for High‐Performance Lithium‐Ion Batteries

AbstractAlthough TiNb2O7 is regarded as a fast‐rechargeable lithium‐ion battery (LIB) anode material, the intrinsic poor electrochemical kinetics of TiNb2O7 still dramatically impedes its development. Herein, an ionothermal synthesis‐assisted doping strategy is proposed for the preparation of a new W6+‐doped TiNb2O7 material (Ti0.95W0.05Nb2O7) with nanoporous structure (denoted as NPTWNO). The improved Li+ diffusion coefficient of NPTWNO suggests that the ionic‐liquid‐templated nanoporous architecture improves the Li+ diffusion kinetics. The density functional theory computational study reveals that the doped W6+ successfully boosts the electronic conductivity due to the narrowed conduction‐valance bandgap resulted from charge redistribution, which is reflected by the electrochemical impedance spectroscopy data. With the simultaneously enhanced Li+ diffusivity and electronic conductivity, NPTWNO achieves fast‐rechargeability in LIBs. Therefore, this work indicates the potential of ionothermal synthesis‐assisted doping strategy on energy storage materials and offers NPTWNO material with promising electrochemical performance.

Nitrogen-doped or boron-doped twin T-graphene as advanced and reversible hydrogen storage media

Two-dimensional (2D) carbon-based (C-based) materials can be regarded as potential hydrogen storage media because of their splendid chemical stability and high specific surface area. Recently, a new 2D carbon allotrope twin T-graphene (TTG) with three-atomic layers thick is reported. Motivated by the above exploration, we employed Density Functional Theory (DFT) computational studies to systematically solve twin T-graphene, nitrogen-doped (N-doped) TTG and boron-doped (B-doped) TTG, and evaluate their performance in hydrogen storage at operable thermodynamic conditions. Six hydrogen molecules were adsorbed on the pristine twin T-graphene, and the hydrogen storage capacity was 7.69 wt%. After N doping and B doping, the twin T-graphene both can adsorb eight hydrogen molecules, and the hydrogen storage capacity was increased to 9.88 wt% and 10.06 wt%, respectively. In addition, we found that the hydrogenation/dehydrogenation (desorption) temperature is predicted to be 241 K. The desorption temperature and desorption capacity of H2 under practical conditions further indicate that it can be used as a reversible hydrogen storage media. This study reveals that twin T-graphene, N-doped and B-doped twin T-graphene are promising hydrogen storage materials with splendid desorption temperature, ideal adsorption energy and high hydrogen storage capacity. Meanwhile, this research will expand the application of heteroatom-doped carbon-based materials.

Enhanced reversible hydrogen storage performance of Mg-decorated g-C2N: First principles calculations

The graphene-like 2D material g-C2N owns superior properties for functional materials development, for instance, its ideal porosity can easily accommodate functional metal atoms, making itself more competitive for energy storage. In this study, density functional theory (DFT) computational studies were employed to solve the electronic structure of Mg-doped g-C2N, and furthermore its potential in hydrogen storage was systematically evaluated. Within our calculations, we found that partial charges of the doped Mg atoms can be successfully transferred to pyridinic N atoms. In one aspect, the Mg atoms can display higher electropositivity, and in another aspect, the N atoms own higher electronegativity. Such a change in electronic structure is favorable to enhance its hydrogen adsorption performance, as the H2 molecules in the vicinity of Mg and N atoms can be easily polarized, and thus the electrostatic attractions can be strengthened. In addition, multiple configurations of the Mg-doped g-C2N with adsorbed H2 molecules were presented also in this study, and we found that each 2 × 2 supercell unit possesses a high gravimetric surface area of 2863 m2/g, and can accommodate at most 44 H2 molecules with the adsorption energies ranging from −0.29 eV to −0.12 eV. With the decoration of Mg, its capacity of hydrogen storage can be as high as 8.03 wt%. The theoretical analysis presented in this study provides important chemical insights for energy materials design, with profound implications for improving the performance of 2D materials’ hydrogen.

Non-oxidative photoreaction of 1,3,5-triaryl-2-pyrazoline-4-ol (4-methoxy) derivatives

• A suitable procedure for the synthesis of 2-pyrazoline-4-ol (-methoxy) derivatives is proposed. • Non-oxidative photochemical reaction of 2-pyrazoline-4-ol (-methoxy) derivatives in CHCl 3 is occurred. • The electronic nature of the substituent on the 4- and 5-positions on the photochemical behavior is studied. • An efficient mechanism for the electron-transfer induced photoelimination reaction in chloroform is proposed. • DFT computational studies (optimization, orbital contour maps, MEP, NBO) at the B3LYP/6-31++(d,p) level of theory on these compoundsare reported. A series of 4-hydroxy- or 4-methoxy-substituted 1,3,5-triaryl-2-pyrazolines were synthesized and their structures, especially trans -orientation of 4- and 5-hydrogens of the 2-pyrazoline ring were characterized by analysis of IR, 1 H NMR, 13 C NMR spectra as well as the single-crystal structure study. In order to elucidate the effect of 4-hydroxy- or 4-methoxy-substitution on the photochemical behavior of these compounds, they were exposed to the UV light. The results explain the occurrence of a non-oxidative photoreaction, by the expulsion of 4-substitution and elimination of a molecule of water or methanol under the formation of the aromatized pyrazole ring. Density functional theory (DFT) calculations were carried out to support the proposed electron-transfer induced photoreaction mechanism. Natural bond orbital (NBO) analysis explains the preferred electron detachment process from the N 1 -atom rather than the oxygen atom of the hydroxy or the methoxy groups. Proton detachment from the involved radical cation species leads to the formation of the radical intermediate centered at the C 5 -position of the heterocyclic ring. Elimination of the hydroxy or the methoxy group accomplished the photoreaction under the formation of the C 4 -unsubstituted pyrazole molecule.