Huajie Feng

The assessment and application of an approach to noncovalent interactions: the energy decomposition analysis (EDA) in combination with DFT of revised dispersion correction (DFT-D3) with Slater-type orbital (STO) basis set

AbstractAn assessment study is presented about energy decomposition analysis (EDA) in combination with DFT including revised dispersion correction (DFT-D3) with Slater-type orbital (STO) basis set. There has been little knowledge about the performance of the EDA + DFT-D3 concerning STOs. In this assessment such an approach was applied to calculate noncovalent interaction energies and their corresponding components. Complexes in S22 set were used to evaluate the performance of EDA in conjunction with four representative types of GGA-functionals of DFT-D3 (BP86-D3, BLYP-D3, PBE-D3 and SSB-D3) with three STO basis sets ranging in complexity from DZP, TZ2P to QZ4P. The results showed that the approach of EDA + BLYP-D3/TZ2P has a better performance not only in terms of calculating noncovalent interaction energy quantitatively but also in analyzing corresponding energy components qualitatively. This approach (EDA + BLYP-D3/TZ2P) was thus applied further to two representative large-system complexes including porphine dimers and fullerene aggregates to gain a better insight into binding characteristics. FigureThe assessment of EDA+DFT-D3/STOs to noncovalent interactions

Synthesis of FeS2 and Co-doped FeS2 films with the aid of supercritical carbon dioxide and their photoelectrochemical properties

The prepared FeS2 and Co-doped FeS2 films revealed better properties in photocurrent response and photocatalysis of water photolysis under simulated sunlight. The films were synthesized on iron substrates with the aid of supercritical carbon dioxide. The experimental results demonstrated that the supercritical carbon dioxide could play an important role in evolution of phases and morphologies during the reaction process. Moreover, the prepared films were characterized by XRD, SEM, TEM and EDS. The UV-vis absorption spectroscopy indicated that the absorption edge has obvious blue shift compared with bulk FeS2. Interestingly, characteristics of photoelectric response and water photolysis were shown by photoelectrochemical experiments under sunlight. Therefore, the prepared films would have an advantage in water photolysis utilizing sunlight.

Two-step synthesis flowerlike calcium carbonate/biopolymer composite materials

The CaCO3/biopolymer composite materials have been prepared by a two-step synthesis. The biopolymer was synthesized from chitosan and acrylic acid in supercritical carbon dioxide, then a large scale of novel flowerlike structured calcite CaCO3 on the biopolymer has been synthesized for the first time by the following process of mineralization. The well-defined flowerlike morphology consisting of orderly and regular petals could be tailored by controlling the reaction time. The morphology evolution of CaCO3 was investigated by the XRD, FTIR and SEM. Moreover, the prepared CaCO3/biopolymer composite materials were further characterized by 1H NMR, HRTEM, SAED and XPS, respectively. The experimental results show that the petal possessed a single crystal structure and consisted of stackings of (18). Interestingly, the product is sensitive to the lower laser power by Raman spectra. Based on experimental results, the growth process of formation of a special shape for CaCO3 was also speculated, which indicates that acrylic acid and chitosan played an important role in forming substrates and in following further mineralization of CaCO3.

Natures of benzene-water and pyrrole-water interactions in the forms of σ and π types: theoretical studies from clusters to liquid mixture

AbstractA combined and sequential use of quantum mechanical (QM) calculations and classical molecular dynamics (MD) simulations was made to investigate the σ and π types of hydrogen bond (HB) in benzene-water and pyrrole-water as clusters and as their liquid mixture, respectively. This paper aims at analyzing similarities and differences of these HBs resulted from QM and MD on an equal footing. Based on the optimized geometry at ωb97xD/aug-cc-pVTZ level of theory, the nature and property of σ and π types of HBs are unveiled by means of atoms in molecules (AIM), natural bond orbital (NBO) and energy decomposition analysis (EDA). In light of the above findings, MD simulation with OPLS-AA and SPC model was applied to study the liquid mixture at different temperatures. The MD results further characterize the behavior and structural properties of σ and π types HBs, which are somewhat different but reasonable for the clusters by QM. Finally, we provide a reasonable explanation for the different solubility between benzene/water and pyrrole/water. FigureThe σ and π types of hydrogen bond as benzene-water and pyrrole-water clusters in gas; Snapshot of benzene/water and pyrrole/water as 1:1 liquid mixture extracted from the MD simulations

From clusters to liquid: what are the preferred ways for benzene and pyrrole to interact?

The various interactions occurring between pyrrole and benzene are a particularly appropriate model, as they are viewed as better X–H···π examples. A combined and sequential use of Quantum Mechanical (QM) calculations and Molecular Dynamics (MD) simulations was applied to investigate the different intermolecular interactions for benzene and pyrrole as clusters and its liquid mixture. All the cluster structures were fully optimized by the B2PLYP-D methods (including dispersion correction) with jun-cc-pVTZ (a revised aug-cc-pVTZ basis set). MD simulation with OPLS-AA force field was used to study the liquid mixture of benzene/pyrrole at different temperatures. Two types of N–H···π hydrogen bonds are preferred interactions compared with C–H···π interactions, either as clusters or as its liquid mixture. Based on the QM results, we clarify the difference in red-shifts of N–H bond of N–H···π hydrogen bonds observed by Jet FT-IR (Phys Chem Chem Phys 10: 2827, 2008). Meanwhile, the nature of various X–H···π interactions is unveiled by atoms in molecules (AIM), natural bond orbital and energy decomposition analysis (EDA). Furthermore, in light of QM results, MD simulation results further characterize the behavior and structural properties of these interactions. Finally, we proposed an original idea to explain the strength variation of different N–H···π hydrogen bond in liquid mixture based on AIM and EDA analysis.Graphical Abstract

A theoretical study of N–H ··· π H-bond interaction of pyrrole: from clusters to the liquid

The N–H ··· π H-bond interactions of clusters and liquid formed by pyrrole molecules were investigated by Quantum Mechanics (QM) and classical Molecular Dynamics (MD), respectively. Based on the optimized geometry at the B97-D/aug-cc-pVTZ level of theory including dispersion correction, the nature and the origin of N–H ··· π H-bond interactions were unveiled by atoms in molecules (AIM), natural bond orbital (NBO), and energy decomposition analysis (EDA). Among them, the AIM analysis gives evidence to the presence of N–H ··· π H-bond interactions, the NBO examination reveals that π → σ* donor-acceptor orbital interaction is of great importance. EDA study indicates that N–H ··· π interactions are governed by the electrostatic and dispersion term. Meanwhile, MD simulation with OPLS-AA (optimized potentials for liquid simulations all-atom) was applied to study the pure liquid pyrrole at different temperature. The results confirm the existence of the N–H ··· π H-bond in the pure liquid pyrrole, and further characterized the structures of this H-bond which is somewhat different to the clusters.