排序方式: 共有22条查询结果,搜索用时 15 毫秒
21.
The structures of the complexes generated by hexamethylenetetramine and nitric acid have been fully optimized by B3LYP method at the 6-311++G** and aug-cc-pVTZ levels. The intermolecular hydrogen-bonding interactions have been calculated by the B3LYP/6-311++G**, B3LYP/aug-cc-pVTZ, MP2(full)/6-311++G** and CCSD(T)/6-311++G** methods, respectively. The NBO (nature bond orbital), AIM (atom in molecule), temperature effect and solvation effect have been analyzed to reveal the origin of the interactions. The results indicate that the stable hydrogen-bonded complexes could be generated by hexamethylenetetramine and nitric acid. The interactions follow the order of (a)>>(e)>(b)>(c)>(d)>(f)>(g). The C-N bonds which are adjacent to the methylene involving the hydrogen bonds tend to break in the chemical reaction. Due to the exothermic process, low temperature is conducive to the formation of the composition, which tallies with the experimental result. 相似文献
22.
用表面张力法、电导法和稳态荧光法研究了手性Gemini表面活性剂[C12-m-C12] Na2(m=2,4,6)和[C12-T-C12] Na2的表面性能及临界胶束聚集数,并计算胶束形成的热力学参数,用圆二色谱法考察了[C12-2-C12] Na2在不同浓度下的立体构型. 结果表明,手性Gemini表面活性剂的临界胶束浓度(cmc)和临界表面张力γcmc随着连接基链长增加或刚性增强而增大;ΔGm0和ΔHm0为负值,|ΔHm0|比|-TΔSm0|小很多,说明胶束化过程为熵驱动的自发放热过程;随着连接基链长增加或刚性增强,ΔGm0和ΔHm0逐渐增大,ΔSm0和临界胶束聚集数逐渐减小,表明其胶束化能力随之降低;当浓度大于cmc时,手性Gemini表面活性剂可形成手性超分子聚集体. 相似文献