THE THEORETICAL STUDIES OF PRODUCT ALIGNMENT OF THE REACTIONS OF Na,F WITH CH_3I

The NaI and IF product rotational alignment of the reactions of Na,F+CH_3I has been theoretically studied in a LEPS PES.The product alignment versus the relative translational energy of the reactants has been obtained.

THEORETICAL STUDIES ON THE INVERSION REACTLON OF BYL(?)OXY LAMINE H_2NOH

The inversion reaction of hydroxy lamine was investigated by using the ab initiointrinsic reaction coordinate(IRC)method with 4-31G basis set.Our results indicate that the ∠H_1NO changes arastically in the vicinity of the transition state while the other bo-nd angles and bond lengths change little throughout the reaction process.

THEORETICAL STUDIES ON THE REACTION MECHANISM OF AMMONIA WITH FORMALDEHY DE

The reaction mechanism of ammonia with formaldehyde was investigated by using the intrinsic reaction coordinate(IRC)method on the ab initio RHF/STO-3G basis set. our results indicate that the reaction proceeds in two stages:the first step yields the molecular complex and the second one is the rearrangement from molecular complex to the reaction proauct.

THEORETICAL STUDIES ON THE UNIMOLECULAR DISSOCIATION OF METHYLFORMATE CATION

The unimolecular dissociation of methylformate free radical cation(CH_3OCHO^+) was studied by ab initio theoretical calculations, Molecular orbital and state correlation diagrams have been examined in the ground and lower excited states. The dissociation mechanism has been explained along the reaction paths. For two possible dissociation pathways in the ground and lower excited states, the activation barriers and reaction heats have been calculated by MCSCF method respectively.

Synthesis, Crystal Structure and Theoretical Studies of (E)-1-((9-(2-(2-methoxyethoxy)ethyl)-9H-carbazol-3-yl)methylene)thiosemicarbazide

A novel thiosemicarbazide derivative, （E）-1-（9-（2-（2-methoxyethoxy）ethyl）-9H-carbazol-3-yl） methylene）-thiosemicarbazide （CMT）, was synthesized and structurally characterized by IR, 1H-NMR, EI-MS and single-crystal X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 14.769（5）, b = 8.279（5）, c = 17.166（5） , β = 114.391（5）°, V = 1911.6（14） 3, Z = 4, F（000） = 784, Dc = 1.287 g/m3, Mr = 370.47, μ = 0.190 mm-1, the final R = 0.0390 and wR = 0.1358 for 1446 observed reflections with Ⅰ 〉 2σ（Ⅰ）. The UV-vis absorption spectra of CMT were explained based on quantum chemical calculations, using time dependent density functional theory （TD-DFT） at the B3LYP/6-31G （d） level.

Theoretical Studies on the Intermolecular Interactions of Aza-calix[2]arene[2]-triazines with RDX

Six fully optimized structures of the aza-calix[2]arene[2]-triazines/RDX supramo-lecular complexes have been obtained at the DFT-B3LYP/6-311＋＋G＊＊ level,and the corresponding intermolecular interactions have been investigated using the B3LYP,mPWPW91 and MP2 methods at the 6-311＋＋G＊＊ level,respectively.The natural bond orbital（NBO） and atoms in molecules（AIM） analyses have been performed to reveal the origin of interactions.To our interest,the result indicates that the strongest interaction is up to-22.34 kJ/mol after basis set superposition error（BSSE） and zero point energy（ZPE） correction at the MP2/6-311＋＋G＊＊ level.Furthermore,the intermolecular interactions between aza-calix[2]arene[2]-triazines with the substituted amidos and RDX are stronger than those of other complexes.Thus,the complexes with amidos can be used as the candidates to increase the stability of explosive and eliminate the explosive wastewater.

Antifouling nanocomposite polymer coatings for marine applications:A review on experiments,mechanisms,and theoretical studies

Marine fouling is a worldwide challenge with huge damages on industrial structures,side effects on economics of industries,and environmental and safety-related hazards.Different approaches have been used for combating fouling in the marine environment.Meanwhile,nanocomposite polymer coatings are a novel generation of antifouling coatings with merits of toxin-free chemical composition and ease of large-scale application.Nanomaterials such as nano-metals,nano-metal oxides,metal-organic frameworks,carbon-based nanostructures,MXene,and nanoclays have antibacterial and antifouling properties in the polymer coatings.Besides,these nanomaterials can improve the corrosion resistance,mechanical strength,weathering stability,and thermal resistance of the polymer coatings.Therefore,in this review paper,the antifouling nanocomposite coatings are introduced and antifouling mechanisms are discussed.This review explicitly indicates that the antifouling efficiency of the nanocomposite coatings depends on the properties of the polymer matrix,the inherent properties of the nanomaterials,the weight percent and the dispersion method of the nanomaterials within the coating matrix,and the chemicals used for modifying the surface of the nanomaterials;meanwhile,the hybrids of different nanomaterials and appropriate chemical agents could be used to improve the antifouling behavior of the prepared nanocomposites.Moreover,the theoretical studies are introduced to pave the way of researchers working on theantifouling coatings,and the importance of the theoretical studies and computational modeling along with the experimental research is notified to develop antifouling coatings with high efficiency.

Theoretical studies on silathione and its unimolecular reactions

The unimolecular reactions of silathione:(a)dehydrogenation,(b)trans-isomerization, (c)cis-isomerization,are investigated by ab initio MO calculations using RHF/4-31G basis set.The geometries and energies of the reactant,transition states and products have been determined on the singlet potential energy surface of the ground state.The reaction ergodography along the intrinsic reaction coordinate(IRC)for the three reactions has also been performed.

Theoretical studies on ammonia oxide and its unimolecular reactions

The unimolccular reactions of ammonia oxide H_3NO,isomerization and dehydrogenation, are investigated by ab initio MO calculations with the 4-31G basis set.The geometries and energies of the reactant,transition states and products have been determined on the singlet potential energy sur- face.The reaction ergodography along the intrinsic reaction coordinate(IRC)for the two reactions have been performed.The vibrational frequency correlation diagram of the two reactions are analyzed along the IRC.

Theoretical studies on structure-property relationships of cellulose and nitrocellulose I.Conformation,stability and conductivity

The banding and electronic structures of a series of long-chain macromolecules of cellu- lose,2-,3-,6-mononitrocellulose,2,3-,2,6-,3,6-dinitrocellulose and trinitrocellulose as well as their structural units(i.e.single-,double-or three-ring systems)have been calculated by both the EH and CNDO/2 methods.The increase of molecular total energies is consistent with the decrease of their stabilities at the three conformations of gg,gt and tg.The Mulliken bond order of O—NO_2 bond is the samllest in each molecule at any of the three conformations,which indicates that this bond is the weakest,and supports the view of initial homolytic cleavage of O—NO_2 bond on slow thermal decomposition.The band gap at the edge of the first Brillouin zone far surpasses 5 eV for cellu- lose,and is less than 3 eV for mono-,di-,and trinitrocellulose.The results show that cellulose is a typical insulator,as we know,and it can be predicted that nitrocellulose has electric conductivity similar to that of semiconductor.

Theoretical studies on the substitution effect of fluorine on ethylene

The substitution effect of fluorine on ethylene is investigated by means of studying the properties of the charge distribution at the bond critical points with the theory of atoms in molecules.It is found that fluorine atom acts not only as a σ electron acceptor,but also as a π electron donor,and these double effects are reflected in the quantity of ellipticity,Lap- lacian and the charge density of charge distribution at the bond critical points.For C—C,C—F bonds,the major axis of elliptical contours is perpendicular to the molecular plane,but for C—H bond,it is parallel to the molecular plane.Other effects originating from the substi- tution have also been discussed.

Theoretical Studies on Structure, Isomerization, and Stability of [Si, O, S]

The structures, energetics, and isomerization of a possible interstellar [Si, O, S] system were explored at the CCSD（T）/aug-cc-pVQZ//CCSD（T）/aug-cc-pVTZ level. On the schemaitc potential energy surface（PES）, we found that silicon oxysulfide（OSiS） produced in laboratory is the global minimum. An analysis of the Wiberg bond index（WBI）, bond order and the bond length, shows that silicon oxysulfide contains SiO and SiS double bonds in ac- cordance with the results of SchnOckel. Besides silicon oxysulfide, another interesting cyclic minimum（c-SiOS） was found to have a very high kinetic stability stabilized by the least barrier of 120.9 kJ/mol. In light of the fact that no cyclic sulfide-containing species has been detected in space, c-SiOS could be a very promising candidate. The presented results might provide useful information on detected interstellar molecules O=Si=S and c-SiOS.

A New Target for Synthesis: Theoretical Prediction for the Reaction between Boron Nitride Nanotube and Dichlorocarbene

Understanding the chemistry of BNNT is a crucial step toward their ultimate practical use. A comparative study of Reactions A （ASWCNT （5,5） and CCl2） and B （ASWBNNT （5,5） and CCl2） have been performed by using ONIOM （B3LYP/6-31G＊： AM1） method in Gaussian03 program package. The results show that （1） the two reactions are both exothermic; （2） the mechanism of Reaction B is a two-step mechanism; （3） the difference in energy barriers suggests that the reaction of CCl2 with BNNT is easier than with CNT; （4） in reaction B, CCl2 prefers to attack the boron atom of BNNT first.

Theoretical Study on the Activity of a-COOH and b-COOH of N-Phosphoryl Aspartic Acids

The bio-mimic reactions of N-phosphoryl amino acids are very important in the study of many biochemical processes. The difference of reactivity between a-COOH and b-COOH in phosphoryl aspartic acid was studied by theoretical study (Hartree-Fock and Density Functional methods) in this paper. The intermediates II containing five-membered ring were more stable than III with six-membered ring. While for intermediates III, the isomers with six-membered ring in apical-equatorial spanning arrangement were more stable than those with di-equatorial spanning arrangement. At B3LYP/6-31G** level, it was shown that transition states IV and V involving a-COOH or b-COOH group had energy barriers of DE = 58.67 kJmol-1 and 103.94 kJmol-1, respectively. These results were in agreement with the experimental data. So the a-COOH group was involved in form of the intramolecular penta-coordinate phosphoric-carboxylic mixed anhydride intermediates, but not b-COOH group.

Theoretical Study on the Reaction of PCl_3/H_2 on Silicon Substrate Surface

The reaction mechanism of PCl3/H2 on silicon substrate surface （simulated by Si4 cluster） was investigated with Density Functional Theory （DFT） at the B3LYP/6-311G^＊＊ level. On silicon substrate, PCl3 firstly undergoes dissociative adsorption, and then the adsorption product reacts with H2 via a four-step multi-channel mode to give the final product PSi4 cluster. The geometries at each stationary point were fully optimized. The possible transition states were determined by vibrational mode analysis and IRC verification. And finally, the main reaction channel was given.

Structures and Properties of Two Pb^Ⅱ Compounds and Theoretical Study of 2,4-Oxybis（benzoic acid）

Two Pb^Ⅱ coordination polymers [Pb（oba）（2,2′-bipy）]·1.5H2O（1） and [Pb（oba）（phen）]（2）（H2oba = 2,4-oxybis（benzoic acid）, 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline） were synthesized by hydrothermal reactions and characterized by single-crystal X-ray diffraction, thermogravimetric analyses, IR spectroscopy and elemental analysis. Structures of compounds 1 and 2 are similar. Compounds 1 and 2 show 1D wavy chains, which are further connected through aromatic π-π stacking interactions to expand into 2D wavelike networks. The crystal structure of 2,4-oxybis（benzoic acid） ligand（3） was obtained, and its full geometry optimization was carried out by using DFT methods at the B3LYP/6-31G（d） level. The calculated data show that the bond distances and bond angles were very close to the experimental data. The values of the frontier orbital energies indicate that this configuration is stable. Moreover, the solid-state fluorescence properties of 1-3 have also been investigated.

Theoretical Study on the Spectroscopic Parameters and Transition Properties of MgH Radical Including Spin-orbit Coupling

An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI＋Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states of MgH are derived. Then the associated spectroscopic parameters are determined and found to be in good accordance with the available experimental results. The permanent dipole moments （PDMs） and the spin-orbit （SO） matrix elements of A-S states are computed. The results show that the abrupt changes of PDMs and SO matrix elements are attributed to the variations of electronic configurations at the avoided crossing point. The SOC effect leads to the five A-S states split into ten Ω states and results in the double potential well of （2）1//2 state. Finally, the transition properties from the （2）1//2, （1）3//2 and （3）1//2 states to the ground state X2∑＋1//2 transitions are obtained, including the transition dipole moments, Franck-Condon factors and radiative lifetimes.

Theoretical Study of Carrier Mobility in Two-Dimensional Tetragonal Carbon Allotrope from Porous Graphene

The carrier mobility of two-dimensional tetragonal carbon allotrope （T-CA） from porous graphene is investigated by first-principles calculations. T-CA can be constructed from divacancy and Stone-Thrower--Wales defects from graphene. T-CA is a direct semiconductor with a band gap of 0.4 eV at F point. T-CA possesses a high carrier mobility of the order of 104 cm2V-ls-1. As our study demonstrates, T-CA has potential applications for next-generation electronic materials.

Theoretical Study on the Pyrolysis Mechanism and Kinetics of 3-Hydroxy-3-Methyl-2-Butanone

The mechanism and kinetics for the decomposition of 3-hydroxy-3-methyl-2-butanone have been studied by using the ab initio RHF/3-21G method. The calculated activation barrier of the reaction is 249.6kJ/mol which is in reasonable agreement with the experimental data (222.2±3kJ/mol). The calculated results show that the decomposition is a concerted process with hydrogen transferring and bond breaking via a five-membered cyclic transition state. The thermal rate constants of the decomposition are obtained by calculating microcanonical probability fluxes through transition state1.

Theoretical Study on the Reaction Mechanism between Dichlorocarbene and Armchair Single-walled Carbon Nanotubes

The reaction mechanism between CC12 and armchair single-walled carbon nanotubes （ASWCNTs） （3,3） and （4,4） has been studied by semiempirical AM1 and ab initio methods. The activation barriers of CC12 adding to ASWCNT （3,3） and （4,4） are computed and compared. The lower barrier of CC12 forms cycloaddition isomer on （3,3） maybe because the strain energy of （3,3） is larger than that of （4,4）. Our theoretical results are consistent with the experimental results.