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Synthesis, Formation Mechanism and Properties of Chiral Mesoporous Materials

Author: QiuHuiBin
Tutor: CheShunAi
School: Shanghai Jiaotong University
Course: Applied Chemistry
Keywords: Mesoporous Chiral Spiral Supramolecular Self-assembly Chiral imprinting
CLC: TB383.4
Type: PhD thesis
Year: 2010
Downloads: 634
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Abstract


Chirality is one of the basic properties of the substance, is widely found in nature. Design and synthesis of chiral compounds, chiral supramolecular aggregates and chiral functional materials has become an important research projects in the field of natural sciences. The last ten years, ordered mesoporous materials because of a high specific surface area, large pore volume, adjustable aperture, multi-functional advantages of universal concern by scientists. Chiral mesoporous material is a highly ordered two-dimensional hexagonal chiral mesoscopic structure of porous materials, since the first reported in 2004, our group has carried out a detailed and in-depth research in this area. This paper systematically summarizes the synthesis of chiral mesoporous materials for more than five years, the formation mechanism and performance and other aspects of the research work conducted and from the research. The thesis is divided into eight chapters, Chapter Summary, the second to the fourth chapter is a study of the synthesis control and formation mechanisms, Chapters 5 and 6 are mainly derived materials synthesis, Chapter VII of the performance study The final chapter concludes with progress. In the second chapter, by the effects of temperature, alkalinity and amino acid surfactants chiral sites on the chiral purity of the substituted groups, we elaborated chiral mesoporous silica chiral purity of the regulation mechanism. The surface active agent to the amino acid having a bulky substituent as templating agent, in the low-temperature synthesis conditions, we get the ee value of more than 90% of the mesoporous silica chiral. The study showed that the formation of the source power of the chiral mesoscopic structure may be from helical stacking of the rod-like micelles of surfactant, while the temperature and the size of the substituent group for the influence of the chiral purity of chiral mesoporous silica can be attributed conformation changes in surfactant molecules. At the same time, the chapter on the ee value with changes in temperature and molecular structure detailed thermodynamic analysis. In addition, was found in the C16-L-Phe-synthesis system as the template agent, low alkalinity is beneficial for the purity of the synthetic master chiral mesoporous silica. For having a larger substituted group of the amino acid surfactant steric intermolecular and intramolecular steric, may also strongly affect the changes in the molecular conformation, thus controlling the stacked direction and chiral surfactant molecular helix The chiral purity of the mesoporous silica. Chapter III, to a variety of non-chiral cationic and anionic surfactant as the template agent, we have synthesized a series of racemic chiral mesoporous silica formed systematically investigated the achiral surfactant guide Mechanism chiral mesoporous silica, the chiral purity of the decision-making mechanism and the helical degree of control mechanisms. The diversity of the molecular structure of the templating agent in a non-chiral and chiral template molecules structural similarity asymmetric molecular forms may be driven non-chiral surfactant guide the fundamental power of the chiral mesoscopic structure is formed. The Mechanical Analysis showed that the chiral mesoporous silica helical cycle length and the crystal diameter is proportional to the torque generated by helical micelles inversely proportional to this torque and the molecular structure of the surface active agent is closely related. In addition, by adding isobutyl charge chiral surfactant, the non-chiral templating agent can be efficiently directed to the formation of the non-racemic chiral mesoporous silica. In the fourth chapter, the study found - octadecyl - bromo-3 - methylimidazole (C18MIMBr), the template agent mesoporous silica synthesis system by precisely adjust the system alkaline, chiral mesoscopic phase can be gradually transformed into a two-dimensional the Quartet p2gg mesoscopic phase, and finally to the layered mesoscopic. , Two-dimensional the Quartet p2gg mesoscopic phase in mesoporous materials are first reported, corresponding to mesoporous silica with elliptical cross section through channels, and arranged in a two-dimensional hexagonal array. In the fifth chapter, chiral anionic surfactant C16-L-Ala and non-chiral anionic surfactant SDS as template BTEE, and BTEB of inorganic precursor, by co-structure-directing agent method, we successfully synthesized methylene and phenylene bridged chiral mesoporous organic silicon oxide, disposable realized the mesopore wall interior and surface bifunctionally. Wherein C16-L-Ala, the ee value of the templating agent synthesized sample can reach 40%, In addition, through a solid diffuse reflection the circular dichroism can be confirmed, the hole wall in the phenylene group may be helically stacked. In the sixth chapter, we introduce a very simple chiral supramolecular porphyrin aggregates assembled into chiral mesoscopic ordered porphyrin - silica composite. This method is unique in that the introduction of a cationic the organosiloxane (TMAPS), it can effectively be a water-soluble anionic porphyrin, for example, four sulfonic acid porphyrin (TPPS), assembled into a columnar spiral stacked body, and then with the other inorganic precursor were assembled to form chiral mesoscopic ordered porphyrin - silica compound material. The experiments show that in these non-chiral synthesis system was added some of the chiral dopant, for example, (R) - and (S) -1,1 '-Bi-2-naphthols, said composite material can be greatly improved hand sexual purity (ee), and reflects the very considerable chiral amplification. In Chapter 7, the solid circular dichroism characterization results confirmed that the extraction of chiral mesoporous silica can be effectively induced by the non-linear chiral anionic conjugated polymer and dish conjugate molecules chiral conformation occurs chiral accumulation, thus indicating the pore walls of the mesoporous silica chiral chiral imprint with supramolecular. In the process of the formation of the chiral mesoporous silica the common structure directing agent (TMAPS) on the quaternary ammonium cation group and the head of the chiral surfactant with the negatively charged carboxyl mutual electrostatic interaction, since the pairing effect, quaternary ammonium salt group may be formed together with the helical micelles helical arrangement, which effectively copy the assembled structure of helical micelles spiral; When the removal of the chiral surfactant quaternary ammonium salt group, the helical arrangement of the array by a covalent bond effectively retained in the wall of the hole, forming a supramolecular chiral imprinting. This chiral blot also chiral molecules such as B-DNA can be identified by.

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