Structure Simulation And Host-guest Interaction Of Histidine,Tryptophan Intercalated Hydrotalcite-montmorillonite Complex

Inorganic functional materials have received widespread attention because of their special structure and properties.The inorganic intercalated complex material is a unique layered material formed by different inorganic laminates and guest layers between layers.The guest has a diversity,so the intercalated complex becomes an effective carrier for many molecules.The paper focuses on the interactive intercalation of two layers of hydrotalcite(LDHs)and montmorillonite(MMT)lamellae,and the histidine and tryptophan are used for the interlayer guest.Firstly,based on the experimental data of LDHs and MMT structure,the His-LDHs-MMT and Trp-LDHs-MMT complex structures were constructed by using the computational chemistry software Material Studio 8.0.According to density functional theory of quantum chemical,the DMol3 code and DND basis of GGA/PW91 were used to optimize the space structure of the complex and compare the system energy of different structures.The stable configurations of three His-LDHs-MMT and two Trp-LDHs-MMT were obtained.The results showed that histidine or tryptophan was bound in a nearly flat form between the hydrotalcite and the montmorillonite lamellae,and there was a certain hydrogen bond and electrostatic interaction with the lamellae.In addition,the XRD patterns of the two complexes were theoretically simulated.The XRD patterns are similar because the amino acids did not change the structure of the lamellae,but different intercalation methods result in different interlayer spacing in the complexes.The characteristic peaks of the XRD shift toward small angles as the layer spacing increases.The(001)characteristic diffraction peak of the montmorillonite layer in the complexes appeared between 20 = 6.5-7.80.The(003)and(110)characteristic diffraction peaks of the LDHs laminae appeared at about 20=11.7,60�,respectively.The study on the intercalated hydrotalcite-montmorillonite complexes provided reference basis for the preparation and application of intercalated composites in the future.The density of States of the complexes showed that the 2p orbitals of oxygen and the ls orbit of hydrogen were dominant near the Fermi level,which indicated the formation of hydrogen bonds in the complex.The charge density data displayed the density field of histidine and tryptophan carboxylic acid anion overlapped with that of hydrotalcite layer,indicating that a strong electrostatic interaction existed between amino acid and hydrotalcite.The analysis of electrostatic potential of complex indicates that the electrostatic interaction between histidine and MMT is obviously stronger than that of LDHs.In order to understand the microstructure of the hydrotalcite-montmorillonite composite,the binding energy of histidine to LDHs and MMT lamellae was calculated by using MS8.0 and Gaussian 09 respectively.The host-guest interactions in the complexes were studied.The calculation results showed that there were specific interactions between the host lamella and the interlayer guest,which are the combination of hydrogen bonding and electrostatic interaction.In the paper,the microstructure of histidine(tryptophan)intercalated hydrotalcite montmorillonite complex was explored.The crystal structure and bonding parameters of the complex were determined by quantum chemical method.The XRD spectrum of the composite crystal was simulated,which provided a theoretical reference for the preparation of the complex.The interaction between histidine and hydrotalcite-montmorillonite lamellae was analyzed by electron density.The paper provided a theoretical basis for the further development of the amino acid intercalated complex materials.