| As an emerging and developing science, supramolecular chemistry is one of the hot areas of research. In the field of supramolecular chemistry, nitrogen-containing heterocyclic ligands get the favor of the chemical workers for its diversity and strong coordination ability. In carboxylic acid ligands, the carboxyl is also a good functional group, and this type of ligands had be used in the supramolecular assembly which have novel structure and special features, so that the nitrogen-containing heterocyclic compounds and carboxylic acid compounds are excellent model in supramolecular chemistry research. In this paper, three kinds of pyrazine compounds and common organic acid ligands were chosen as the main object of study to synthesis a series of supramolecular compounds through controlling the reaction conditions and influencing factors with the conventional solution method at room temperature. Use a single crystal diffraction X-ray, elemental analysis, IR and TGA to characterize the supramolecular structural and properties. The paper is divided into four chapters:In chapter1, introduce the basic concepts of supramolecular chemistry and crystal engineering and their research methods. Reviews on the search status of supramolecular chemistry, synthetic methods and factors affecting the crystal growth.In chapter2, we chose2,3,5,6-tetramethylpyrazine and the following coformers that contain multifunctional groups:1,4-cyclohexanedicarboxylic acid,2,6-dihydroxybenzoic acid,2,6-pyridinedicarboxylic acid,2-hydroxy-6-naphthoic acid,3-nitrophthalic acid, o-phthalic acid and3-hydroxybenzoic acid as building blocks. Compounds18has been reported, but we use a different method to analysis and characterize it. Eight crystals of2,3,5,6-tetramethylpyrazine with carboxylic acids were as follows:(1)[(C8H12O4)·(C8H12N2)0.5] (2)[(C7H6O4)2·(C7H5O4)-·(C8H13N2)+·(C8H12N2)0.5](3)[(C7H5NO5)·(C8H12N2)0.5·H2O](4)[(C11H8O3)2·(C8H12N2)](5)[(C8H5NO6)·(C8H12N2)0.5·H2O](6)[(C8H6O4)·(C8H12N2)](7)[(C8H6O4)·(C8H12N2)0.5](8)[(C7H6O3)·(C8H12N2)1.5] These compounds were tested and analyzed the crystal structure and to study the effects of hydrogen bonding and supramolecular synthon for its structures. Focuses on the synthesis conditions of these supramolecular compounds, in directional adjustment of substituent effects, analyze supramolecular structure and formation patterns. And enrich the research of supramolecular chemistry of similar nitrogenous ligand with organic acid ligand at the same time.In chapter3, we chose2,3-dimethylpyrazine as a nitrogen containing ligand,2-hydroxy-6-naphthoic acid,3-nitrophthalic acid,5-chlorosalicylic acid, salicylic acid,2,3-dihydroxybenzoic acid and2,6-dihydroxybenzoic acid as acidic ligands to synthesis three-dimensional supramolecular network structure9-14:(9)[(C11H8O3)2·(C6H8N2)·(CH4O)·H2O](10)[(C8H5NO6)·(C8H8N2)](11)[(C7H5ClO3)·(C6H8N2)](12)[(C7H6O3)·(C6H8N2)0.5](13)[(C7H6O4)·(C6H8N2)](14)[(C7H5O4)·(C6H9N2)] It is realized that the supramolecular structures is diversity by changing the ratio of materials, solvents and reaction conditions. And characterized the structure, discussed the influence of the hydrogen bonding and supramolecular synthon for their structures.In chapter4, under general conditions, we chose2,6-dimethylpyrazine as a nitrogen containing ligand,2,5-dihydroxybenzoic acid,3-nitrophthalic acid, tetrafluoroterephthalic acid and5-nitroisophthalic acid as acidic ligands with the main line of designing and synthesizing of novel supramolecular structure to synthesis three-dimensional supramolecular network structure15-18:(15)[(C7H6O4)·(C6H8N2)](16)[(C8H5NO6)·(C6H8N2)](17)[(C8H2F4O4)·(C6H8N2)] (18)[(C8H5NO6)2·(C6H8N2)2·2H2O] And they were carried out structural analysis and characterization, and explore the influence of hydrogen bonds and supramolecular synthons for their structures. |
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