Theoretical Study on the Intermolecular Interactions between 1,1‐Diamino‐2,2‐Dinitroethylene and H2O

The density functional method was applied to the study of 1,1‐diamino‐2,2‐dinitroethylene (Fox‐7)/H₂O dimer. All the possible dimers ( 1, 2 and 3 ), as well as the monomers, were fully optimized with the DFT method at the B3LYP/6‐311++G^** level. The basis set superposition errors (BSSE) are 4.62, 4.07 and 3.45 kJ/mol, and the zero point energy (ZPE) corrections for the interaction energies are 7.94, 5.66 and 6.40 kJ/mol for 1, 2 and 3 , respectively. Dimer 1 is the most stable, judged by binding energy. After BSSE and ZPE corrections, the greatest corrected intermolecular interaction energy of dimer 1 was predicted to be ?29.36 kJ/mol. The charge redistribution mainly occurs on the adjacent N–H··· O atoms and N–O··· H atoms between submolecules. The oxygen in the nitro group acts as a moderate hydrogen acceptor as compared to water oxygen. Based on the statistical thermodynamic method, the standard thermodynamic functions, heat capacities (C⁰_P), entropies (S⁰_T) and thermal corrections to enthalpy (H⁰_T), and the changes of thermodynamic properties on going from monomer to dimer over the temperature range 200.00‐700.00 K were predicted. It is energetically or thermodynamically favorable for Fox‐7 to bind with H₂O and to form dimer 1 at room temperature.     

Preparation of glucose-sensitive microcapsules with a porous membrane and functional gates

A glucose-sensitive microcapsule with a porous membrane and with linear-grafted polyacrylic acid (PAAC) chains and covalently bound glucose oxidase (GOD) enzymes in the membrane pores acting as functional gates was successfully prepared. Polyamide microcapsules with a porous membrane were prepared by interfacial polymerization, PAAC chains were grafted into the pores of the microcapsule membrane by plasma-graft pore-filling polymerization, and GOD enzymes were immobilized onto the PAAC-grafted microcapsules by a carbodiimide method. The release rates of model drug solutes from the fabricated microcapsules were significantly sensitive to the existence of glucose in the environmental solution. In solution, the release rate of either sodium chloride or VB(12) molecules from the microcapsules was low but increased dramatically in the presence of 0.2mol/L glucose. The prepared PAAC-grafted and GOD-immobilized microcapsules showed a reversible glucose-sensitive release characteristic. The proposed microcapsules provide a new mode for injection-type self-regulated drug delivery systems having the capability of adapting the release rate of drugs such as insulin in response to changes in glucose concentration, which is highly attractive for diabetes therapy.     

St-DVB凝胶化反应动力学机理的模型理论研究

高分子凝胶化反应对功能高分子骨架结构有重要影响，它经历溶胶一凝胶的不可逆转变（sol－geltransition）；导致高分子网络结构及分子尺寸的突变，动力学过程和机理十分复杂，因此，人们对这一领域的研究始终贯注了巨大兴趣．追溯过去，人们对高分子凝胶化过程的研究经历了由未考虑环化、搭环的Flory－stockmayer理论问；静态渗流理论［’］到动态凝胶化模型＊三个发展阶段·后者除克报了前两种的不足外，还引入了与几何形状密切相关的动态标度处理方法．近年来，分形概念的产生更激励了动态标度的发展，这种增长模型的研究方法考虑了增长…     

Total Synthesis of Phakellistatin 13 by Solution Method

Since George R. Pettit’s group isolated cycloheptapeptide phakellistatin 1 from sponge1, over ten similar cyclic peptides have been obtained2-5. Phakellistatin 134 (Figure 1) is a cycloheptapeptide isolated from the brown snubby sponge from the South Chi…     

Synthesis of Snake-cage Resins and Study of Their Separation Ability

IntroductionSnake-cageresin,alsoca1ledsnake-cagepolyelectrolyte['],isaspecialkindofamphotericresin.ItwasfirstinvestigatedbyHatchM.J.etal.in1957[z].Thetypicalandusefulsnake-cageresinisRetardation11A-8(l1A-8inthecon-text)manufacturedbyDowChemicalCoI,TD.Itissynthesizedbypolymerizingacrylicacidinsidethenetworkofastrongbasicanionexchangeresinwith8%crosslinking.Thus,theresinconsistsofacrosslinkedpolymermatrix,cage,andalinearpolymer,socalledsnake,whichisphysicallytrappedinsidethecage.Thecagepol…     

3-碘-苯并吡喃-4-酮与硫脲类反应的研究

3-碘-苯并吡喃-4-酮(1)与硫脲发生Micheal加成反应, 合成三个2-硫代-5-(2-羟基苯甲酰基)咪唑衍生物和五个2-亚氨基-5-(2-羟基苯甲酰基)噻唑衍生物。这些化合物结构经核磁共振光谱、红外光谱和元素分析均予以证实。     

大气中HCO^+→COH^+异构化的理论分析

在从头算的基础上, 对标题反应进行了统计热力学和含Wigner校正的过渡态理论的动力学分析。给出了1.01325×10^5Pa及200-2500K温度下的反应物、产物和过渡态的热力学函数及该异构化的平衡常数、速率常数和A因子等一套较完整的热力学、动力学参数。     

芳香叔胺引发丙烯酰胺光聚合动力学及机理研究

研究了N,N-二甲基对甲苯胺(DMT)为引发剂时丙烯酰胺(AM)的光聚合。聚合速率与AM、DMT浓度的关系为: R_p∞[DMT]~(0.35)[AM]~(1.34)(水为溶剂) R_p∞[DMT]~(0.33)[AM]~(1.32)(二甲亚砜为溶剂)二甲亚砜为溶剂时,光聚合表观活化能为4.62千卡/克分子。 从光照下DMT与AM形成激发态电荷转移复合物的机制初步讨论了引发机理。     

Hyperbranching polymerization of aziridine on silica solid substrates leading to a surface of highly dense reactive amine groups

Silica solid substrates such as fused silica, silicon wafers with a natural oxide layer, and glass were treated with aziridine to produce reactive primary amine groups on the top surface. We found that the hydroxyl group on the substrate was able to initiate the ring-opening polymerization of aziridine, resulting in highly branched poly(ethyleneimine) on the surface. In dichloromethane, the thickness of the organic film reached 25 A in 20 h and the absolute density of the primary amine group on the surface was 23 amines/nm(2). Atomic force microscopy shows an embossed morphology after the polymerization in dichloromethane, while use of toluene gives a rather smooth surface. The resulting organic layer shows high thermal and pH stability.     

Anionic ligand effect on the nature of epoxidizing intermediates in iron porphyrin complex-catalyzed epoxidation reactions

We have studied an anionic ligand effect in iron porphyrin complex-catalyzed competitive epoxidations of cis- and trans-stilbenes by various terminal oxidants and found that the ratios of cis- to trans-stilbene oxide products formed in competitive epoxidations were markedly dependent on the ligating nature of the anionic ligands. The ratios of cis- to trans-stilbene oxides obtained in the reactions of Fe(TPP)X (TPP = meso-tetraphenylporphinato dianion and X(-) = anionic ligand) and iodosylbenzene (PhIO) were 14 and 0.9 when the X(-) of Fe(TPP)X was Cl(-) and CF(3)SO(3)(-), respectively. An anionic ligand effect was also observed in the reactions of an electron-deficient iron(III) porphyrin complex containing a number of different anionic ligands, Fe(TPFPP)X [TPFPP = meso-tetrakis(pentafluorophenyl)porphinato dianion and X(-) = anionic ligand], and various terminal oxidants such as PhIO, m-chloroperoxybenzoic acid (m-CPBA), tetrabutylammonium oxone (TBAO), and H(2)O(2). While high ratios of cis- to trans-stilbene oxides were obtained in the reactions of iron porphyrin catalysts containing ligating anionic ligands such as Cl(-) and OAc(-), the ratios of cis- to trans-stilbene oxide were low in the reactions of iron porphyrin complexes containing nonligating or weakly ligating anionic ligands such as SbF(6)(-), CF(3)SO(3)(-), and ClO(4)(-). When the anionic ligand was NO(3)(-), the product ratios were found to depend on terminal oxidants and olefin concentrations. We suggest that the dependence of the product ratios on the anionic ligands of iron(III) porphyrin catalysts is due to the involvement of different reactive species in olefin epoxidation reactions. That is, high-valent iron(IV) oxo porphyrin cation radicals are generated as a reactive species in the reactions of iron porphyrin catalysts containing nonligating or weakly ligating anionic ligands such as SbF(6)(-), CF(3)SO(3)(-), and ClO(4)(-), whereas oxidant-iron(III) porphyrin complexes are the reactive intermediates in the reactions of iron porphyrin catalysts containing ligating anionic ligands such as Cl(-) and OAc(-).