De-Quan Wang

Reaction Mechanism of HCN+ + C2H4: A Theoretical Study

The complex doublet potential energy surface for the ion-molecule reaction of HCN(+) with C(2)H(4) is investigated at the B3LYP/6-311G(d,p) and CCSD(T)/6-311++G(3df,2pd) (single-point) levels. The initial association between HCN(+) and C(2)H(4) forms three energy-rich addition intermediates, 1 (HCNCH(2)CH(2)(+)), 2 (HC-cNCH(2)CH(2)(+)), and 3 (N-cCHCH(2)CH(2)(+)), which are predicted to undergo subsequent isomerization and decomposition steps. A total of nine kinds of dissociation products, including P(1) (HCN + C(2)H(4)(+)), P(2) (HCNCHCH(2)(+) + H), P(3) (NCCH(2) + CH(3)(+)), P(4) (CN + C(2)H(5)(+)), P(5) (NCCHCH(2)(+) + H(2)), P(6) (HNCCHCH(2)(+) + H), P(7) (c-CHCCH(2)N(+) + H(2)), P(8) (c-NHCCH(2)C(+) + H(2)), and P(9) (HNCCCH(+) + H(2) + H), are obtained. Among the nine products, P(1) is the most abundant product. P(2) is the second feasible product but is much less competitive than P(1). P(3), P(4), P(5), and P(6) may have the lowest yields observed. Other products, P(7), P(8), and P(9), may become feasible at high temperature. Because the intermediates and transition states involved in the most favorable pathway all lie below the reactant, the HCN(+) + C(2)H(4) reaction is expected to be rapid, which is confirmed by experiment. The present calculation results may provide a useful guide for understanding the mechanism of HCN(+) toward other unsaturated hydrocarbons.

Theoretical study of the C(3P) + trans-C4H8 reaction.

The complex triplet potential energy surface for the reaction of ground-state carbon atom C((3)P) with trans-C(4)H(8) is theoretically investigated at the B3LYP/6-311G(d,p) and G3B3(single-point) levels. Various possible isomerization and dissociation pathways are probed. The initial association between C((3)P) and trans-C(4)H(8) is found to be the C((3)P) addition to the C=C bond of trans-C(4)H(8) to barrierlessly generate the three-membered cyclic isomer 1 CH(3)-cCHCCH-CH(3). Subsequently, 1 undergoes a ring-opening process to form the chainlike isomer 3a cis-trans-CH(3)CHCCHCH(3), which can either lead to P(6)((2)CH(3)CHCCCH(3) + (2)H) via the C-H bond cleavage or to P(7)((2)CH(3)CHCCH + (2)CH(3)) via C-C bond rupture. These two paths are the most favorable channels of the title reaction. Other channels leading to products P(1)((2)CH(3)-cCHCCH + (2)CH(3)), P(2)((2)CH(3)-cCHCC-CH(3) + (2)H), P(3)(trans-(2)CH(3)CHCH + (2)C(2)H(3)), P(4)(cis-(2)CH(3)CHCH + (2)C(2)H(3)), P(5)((3)CH(3)CH + (1)CH(3)CCH), P(8)(cis-(2)CH(3)CHCHCCH(2) + (2)H), P(9)(trans-(2)CH(3)CHCHCCH(2) + (2)H), P(10)((2)CH(3)CCCH(2) + (2)CH(3)), and P(11)((2)CH(3)CHCCHCH(2) + (2)H), however, are much less competitive due to either kinetic or thermodynamic factors. Because the intermediates and transition states involved in the C((3)P) + trans-C(4)H(8) reaction all lie below the reactant, the title reaction is expected to be rapid, as is consistent with the measured large rate constant. Our results may be helpful for future experimental investigation of the title reaction.

Evaporation-induced morphology pattern of triblock copolymer A 5 B 10 C 5 in thin film: A multibody DPD simulation study

We used multibody dissipative particle dynamics method, by which the attractive and repulsive interactions can be effectively considered, to investigate the evaporation-induced morphology patterns of triblock copolymer A5B10C5 in thin film. With changing attractive interactions between solvent vapor and triblock copolymer that represent various selective solvents, lamellar morphology, sandwich lamellar morphology, spherical morphology and disorder morphology patterns of the thin films were obtained for both coil-coil-coil and rod-coil-coil chain architectures, respectively. The order parameter and the film thickness were calculated during the process for characterizing the film properties, and it was found that the rigid A-block of the triblock copolymer hinders the formation of an ordered structure.

Theoretical Study of HCN + + C2H2 Reaction

A detailed theoretical investigation for the ion-molecule reaction of HCN (+) with C 2H 2 is performed at the B3LYP/6-311G(d,p) and CCSD(T)/6-311++G(3df,2pd) (single-point) levels. Possible energetically allowed reaction pathways leading to various low-lying dissociation products are probed. It is shown that eight dissociation products P 1 (H 2C 3N (+)+H), P 2 (CN+C 2H 3 (+)), P 3 (HC 3N (+)+H 2), P 4 (HCCCNH (+)+H), P 5 (H 2NCCC (+)+H), P 6 (HCNCCH (+)+H), P 7 (C 2H 2 (+)+HCN), and P 8 (C 2H 2 (+)+HNC) are both thermodynamically and kinetically accessible. Among the eight dissociation products, P 1 is the most abundant product. P 7 and P 3 are the second and third feasible products but much less competitive than P 1 , followed by the almost negligible product P 2 . Other products, P 4 (HCCCNH (+)+H), P 5 (HCNCCH (+)+H), P 6 (H 2NCCC (+)+H), and P 8 (C 2H 2 (+)+HNC) may become feasible at high temperatures. Because the intermediates and transition states involved in the reaction HCN (+) + C 2H 2 are all lower than the reactant in energy, the title reaction is expected to be rapid, as is consistent with the measured large rate constant at room temperature. The present calculation results may provide a useful guide for understanding the mechanism of HCN (+) toward other pi-bonded molecules.