Preparation And Characterization Of Intercalated Complexes Of Proline、 Histidine、tryptophan LDH-MMT

The layered material is one of the hot spot of chemical research, due to its unique structure it has been widely used in many fields. Hydrotalcite, hydrotalcite-like compound and montmorillonite are typical of layered materials. Hydrotalcite and hydrotalcite-like compound layer board are mainly composed of metal hydroxides and interlayer anions; due to interlayer anionic exchangeability they have great potential in many fields such as catalysis and ion carriers. Montmorillonite is a kind of aluminum silicate clay mineral with exchangeable interlayer cation and has been widely used in the field of medicine and chemical industry. In order to study the structure of the layered material features, excavate the potential applications of the single layer material, we used the amino acids as the guest molecule to prepare bipolar layered compounds containing both characteristics of hydrotalcite and montmorillonite layer board.First we used co-precipitation methods to prepare Mg-Al hydrotalcite (LDH) and proline intercalated Mg-Al hydrotalcite (Pro- LDH), at the same time introducing proline to montmorillonite interlayer to prepare proline intercalated montmorillonite. All the samples were characterized by XRD, FT-IR, TG-DTA and SEM. XRD spectra showed that Pro-LDH 003 diffraction plane characteristic peak position with LDH 003 diffraction plane characteristic peak position had certain deviation, the LDH d003 experimental value was 0.79nm and the Pro-LDH was 0.81nm, the value of d003 is the layer board spacing, suggesting that proline was inserted into the LDH layer board. FT-IR and TG-DTA graphs characterized the characteristics of the proline intercalated LDH from the molecular groups characteristic peak and thermal stability. By comparing the XRD spectrum diagram of the single montmorillonite, proline intercalated montmorillonite layer spacing single montmorillonite increased, showing that proline was successfully inserted into montmorillonite layer board. The Pro-LDH and Pro-MMT was delaminated by formamide and deionized water. The delaminated solutions were mixed in different mass ratios and the products were characterized by XRD, FT-IR, TG-DTA and SEM. SEM results showed that when the LDH:MMT=4:1, the composite morphology was same to the MMT, with the increase of content of hydrotalcite, crimp morphology is reduced, the overall shape was close to the LDH. Hydrotalcite layer board thickness was 0.48 nm, montmorillonite layer board thickness was 0.91～0.95 nm. By parallel experiments, the results of XRD characterization indicated that when the mass ratio was 1:4 and 1:2, compound layer board spacing was 1.42 nm and 1.43 nm. Two kinds of composite product layer spacing was close to the sum of LDH and MMT single layer spacing, suggesting that product may be formed by hydrotalcite layer board and montmorillonite layer board, the connection between layer board were monolithic connections. When the mass ratio was 1:1,2:1 and 4:1, the compound layer board spacing was 1.63 nm, 1.64 nm and 1.76 nm, layer board spacing was big, suggesting that the body of the compound was montmorillonite; arrangement of the LDH between the layers was more complicated. When the mass ratio was 8:1, compound layer board spacing was 1.68 nm, the body was hydrotalcite, and compound layer board peak strength was weak. When the mass ratio was 10:1 and 15:1, the MMT 001 diffraction plane characteristic peak disappeared, indicating that the main part of product was LDH layer board. At the same time, lamella was in long-range disordered arrangement because of the influence of delamination.In order to explore the influence of other amino acids on intercalated layer structure, we used histidine and tryptophan as the interlayer ion to carry out parallel experiments. XRD characterization showed that the doo3 values of LDH, Pro-LDH, His-LDH, Trp-LDH, were 0.79,0.81,0.88, 0.92 nm, and that of MMT, Pro-MMT, His-MMT, Trp-MMT was 1.28, 1.36,1.35,1.49 nm, respectively. From the layer spacing of intercalation compound we could see that compared to proline, histidine and tryptophan had more obvious effect on the changes of the structure of layered materials. The d001 values of histidine and tryptophan compounds were between 1.46～1.54 nm, conforming to the layer spacing of double-layer plate layered compound. The results showed that three kinds of amino acids could be used as object ions into LDH and MMT lamella to prepare the double-layer layered compounds.