Synthesis And Nonlinear Optics Property Of Chiral Camphoric Metal-Organic Frameworks

Metal-Organic Frameworks (MOFs) is one kind of new hybrid organic-inorganic materials connected by coordination bonds between metals or metal-based points (second building units) as nodes and organic ligands as linkers. Now MOFs has attracted great attention these years and has many potential applications in the fields of energy resources, environment and biology, such as gas storage, heterogeneous catalysis, medical diagnosis and drug transportation, etc.This paper designed and synthesized four highly stable Metal-Organic Frameworks built from camphoric derivatives'ligands, Zn2+and Cd2+ions. Discuss the relationship between structures and properties, and study their properties, such as nonlinear optics, optical catalysis and small molecule sensors according to their structures. The research results accumulated practice and theory experience for the design and synthesis of functional Metal-Organic frameworks.Based on the chirality of camphoric acid and conjugation structure of pyridinamine, design and synthesize two chiral conjugated organic ligands L1((1R,3S)-1,2,2-trimethyl-3-(pyridin-4-ylcarbamoyl)cyclopentanecarboxylic acid) and L2((1R,3S)-1,2,2-trimethyl-3-(pyridin-3-ylcarbamoyl)cyclopentanecarboxylic acid). Then four Metal-Organic frameworks including ZnLl2(H2O)2 (MOF1), CdLl2(H2O)2 (MOF2), ZnL22(MeOH)2 (MOF3) and Zn2L22BDC (BDC=1,4-benzenedicarboxylic acid) (MOF4) were synthesized by solvothermal methods.Study demonstrates that two colorless crystals MOF1 and MOF2 were synthesized by chiral conjugated structure Ll, Zn2+and Cd2+respectively. Single crystal X-ray diffraction analysis shows two MOFs belong to chiral space group C2. Powder second harmonic generation (SHG) test shows that MOF1 and MOF2 display SHG efficiencies that are approximately 2.8 and 2.6 times than that of inorganic nonlinear optical crystal potassium dihydrogen phosphate (KDP), respectively, proving the probability and feasibility of structure design.Colorless crystal MOF3 was synthesized by another chiral camphoric derivatives' ligand L2 and Zn2+.Single crystal analysis shows that MOF3 has space group P43212 with three-dimensional network structure. Powder SHG test displays MOF3 has no SHG efficiencies, due to less parallel arrangement of conjugated structure in MOF3 than that in MOF1.In order to investigate second building units'structures in MOFs, MOF4 was synthesized by L2, BDC and Zn2+. Single crystal analysis shows MOF4 has space group P-1 with two-dimensional structure. MOF4 shows potential sensors for small molecule. MOF4 displays fluorescence increase effect to alcohol compounds such as methanol, ethanol and isopropanol, while MOF4 displays fluorescence decrease effect to phenyl compounds such as nitrobenzene, phenol,1,3-dichlorobenzene.