Synthesis And Properties Of Nanometer Amino Acid-Heteropoly Acid Charge-transfer Compounds By Low-heating Solid-state Chemical Reaction

Heteropoly compounds have attracted considerable interest for their applicationprospects in many fields of catalysis, antiviral activity, nolinear optical and magneticmaterials owing to their unique structure. Heteropoly anions are suitable to be acceptorsof new-style charge-transfer compounds in view of their firm size and conformation,multi-electron reduction capacity. So, heteropoly compounds can be good photochromicmaterials. At present, study on synthesis of nanometer heteropoly compounds is a frontierproblem in materials field. Especially, little attention is paid to the preparation ofheteropoly compounds with 1D nanotubular structure. The reported methods for preparing1D nanomaterials usually require rigorous conditions including high reactiontemperatures, tedious procedures and long synthesis time. Therefore, the development ofmild and convenient methods for synthesizing nanotubular materials is a currentchallenge. As one of synthesis methods for nanomaterials, low-heating solid-statechemical reaction has advantage of free of solvent, lack of pollution, high efficiency,good selectivity and convenient operation, so it shows enormous potential on thepreparation of nanomaterials. In this paper, low-heating solid-state chemical reaction,which is a novel approach of preparing nano powder was applied to synthesize nanometerheteropoly compounds. A series of amino acid -heteropoly acid compound nanotubes andnanoparticles were synthesized from Keggin-type, Dawson-type heteropoly acid andamino acids. The photochromic and electrochemical properties of products were stuided.The main content of this paper is divided into four chapters.In the first chapter, amino acid -heteropoly acid charge-transfer compound nanotubeswere synthesized from four Keggin-type heteropoly acids and aromatic series aminoacid ―tyrosine (Tyr) by one-step solid-state chemical reaction at room temperature. Thecompositions of products were determined by means of elemental analysis, IR, TG-DTAand XRD. The tube-like morphology of products was observed by TEM. Thephotochromism of products was studied by UV. Results show that the products preparedfrom Keggin-type molybdenum heteropoly acids possess photochromism, but thephotochromism of products prepared from Keggin-type tungsten heteropoly acids arevery weak. The photochromism of products prepared from Keggin-type molybdenumheteropoly acids are irreversible. The electrochemical properties of the products werecharacterized by CV. The results show that the redox properties of products are similar tothose of corresponding Keggin-type heteropoly acids, the potential value of products isclose to that of heteropoly acids, which indicates tyrosine cation's coming intocounterbalance position has little effect on the redox properties of heteropoly compounds.Heteropoly anions are active species of electrochemical reduction in solution. In the second chapter, a series of nanometer amino acid -heteropoly acidcharge-transfer compounds were synthesized from four Keggin-type heteropoly acids andaromatic series amino acids ―phenylalanine (Phe), fatty series amino acid ―threonine(Thr), and heterocycle series amino acid ―tryptophane (Trp) by one step solid statereaction at room temperature. The compositions of products were determined by means ofelemental analysis, IR, TG-DTA and XRD. The morphology of products was observed byTEM. Comparing to the first chapter, we found that the structure of organic donor has aneffect on the morphology of Keggin-type heteropoly compounds. When different organicdonor reacted with the same heteropoly acid, the morphology of the products is obviouslydifferent. We speculate that we can control the morphology of heteropoly compounds bychanging structure of organic donor. The photochromism of products were studied by UV.The effect on the photochromism of products by organic donor and heteropoly acidacceptor was discussed. Results indicate that the photochromism of heteropolycompounds is in relation to either capacity of electron acceptance by heteropoly acids orcapacity of electron donation by organic donor. When heteropoly acids are same, thebetter capacity of electron donation organic donors possess, the stronger photochromismproducts possess. When organic donors are same, the better capacity of electronacceptance heteropoly acids possess, the stronger photochromism products possess. Wealso found by UV that the charge-transfer interaction of organic donors which have anamino-group at the benzene ring and molybdenum heteropoly acids would be occurredduring the procedure of reaction. In the third chapter, Dawson-type heteropoly charge-transfer compound nanotubeswere synthesized from two Dawson-type heteropoly acids and aromatic series aminoacid ―tyrosine (Tyr) by one-step solid-state reaction at room temperature. Thecompositions of products were determined by means of elemental analysis, IR, TG-DTAand XRD. The tube-like morphology of products was observed by TEM. Thephotochromism of products were studied by UV. Results show that the product fromDawson-type molybdenum heteropoly acids possesses photochromism, but the...