Study On The Interaction Between Quinazoline And Coumarin Derivatives And Heavy Metal Ions

Heavy metal pollution has severe impact on ecological environment and human health. To detect heavy metal ions in complicated aqueous environment accurately and instantly are of great importance for environmental chemistry and bio-medicinal research. Therefore, organic fluorescent probe has a broad application prospect in the field of detecting metal ions due to its advantages of simple synthesis, high sensitivity, good selectivity, and rapid response. In this thesis, we designed and synthesized multiple series of organic ligands based on the fluorophore of quinazoline and coumarin derivatives, and tested their fluorescence sensing properties and biocompatibilities, and studied on the interaction between quinazoline and coumarin derivatives and heavy metal ions, such as copper(II)、zinc(II)、nickel(II)、cobalt(II)、manganese(II), and discussed the feasibility of these new organic ligands as the cation detection reagent. The main results are as below:1. Six quinazolines derivatives were designed and synthesized, on the basis of experimental results, a plausible reaction mechanism for the formation of quinazolines-type ligand was proposed. Six new quinazoline derivatives have been synthesized by the reaction of o-aminoacetophenone oxime with 3, 5-dichlorosalicylaldehyde, 3, 5-dibromosalicylaldehyde, 4-bromosalicylaldehyde, 2, 4-dichloro benzaldehyde, 2-pyridyl formaldehyde, 3-pyridyl formaldehyde, respectively. Six quinazoline derivatives are:2-(3, 5-dichloro-2-hydroxyphenyl)-4-methyl-1, 2-dihydroquinazoline 3-oxide(HL1), 2-(3, 5-dibromo-2-hydroxyphenyl)-4-methyl-1, 2-dihydroquinazoline 3-oxide(HL2), 2-(4-bromo-2-hydroxyphenyl)-4-methyl-1, 2-dihydroquinazoline 3-oxide(HL3), 2-(2, 4-dichlorophenyl)-4-methyl-1, 2-dihydroquinazoline 3-oxide(HL4), 2-(2-pyridyl)-4-methyl-1, 2-dihydroquinazoline 3-oxide(HL5), 2-(3-pyridyl)-4-methyl-1, 2-dihydroquinazoline 3-oxide(HL6). All the ligands have been characterized by 1H NMR and mass spectrum and also solubility experimental analysis. HL1 and HL2 have been determined by X-ray single crystal diffraction. HL1 and HL2 adopt a V-shaped configuration, in which the benzene rings are approximately perpendicular. In the crystal structure, with the help of one pair of intermolecular N1-H1···O1 hydrogen bond and two pairs of C-H···π(C5-H5···Cg3, C15-H15B···Cg2) interactions, HL1 formed an infinite 3-D supramolecular network along c-axis. Molecules of HL2 are connected by two pairs of intermolecular N2-H2A···O1 and O2-H2···Br1 hydrogen bonding, C11-H11···Cg(2), and π(ph)···π(ph) stacking interactions such as C5-Br2···Cg(3) and Cg(2)···Cg(2), which play an important role in stabilizing the structure of the crystal. In conclusion, with the help of hydrogen bonds and other weak interactions, adjacent molecular units are linked together by interactions to give an infinite 2-D chain supramolecular structure along a-axis.2. Selected the ligand HL1 to recognize other metal ions, such as Hg2+,Pb2+,Cu2+,Zn2+,Cd2+,Ni2+,Co2+,Ba2+,Cr3+,and Mg2+ in methanol solution, and react with different transition metal salts, for example, Co(CH3COO)2·4H2O, Zn(CH3COO)2·2H2O, Ni(CH3COO)2·4H2O and obtained three metal complexes by using the natural evaporation method. HL1 and its corresponding Co(III), Zn(II), Ni(II) complexes were analyzed using IR, UV-Vis, and emission spectroscopy, elemental analysis and single-crystal X-ray crystallography. The spectroscopic data of the Co(III), Zn(II), Ni(II) complexes were compared with the ligand HL1. The electrochemical properties of the metal complexes were determined by cyclic voltammetry. In addition, SOD-like activities of HL1 and Ni(II) complex were also investigated. The geometries and electronic properties of both the ligand HL1 and the metal complexes were studied by DFT calculation. Moreover, the calculated HOMO and LUMO energies show the character of the ligand HL1 and the metal complexes.3. Selected the ligand HL2 to recognize other metal ions, such as Hg2+,Pb2+,Cu2+,Zn2+,Cd2+,Ni2+,Co2+,Ba2+,Cr3+,and Mg2+ in methanol solution, and react with different transition metal salts, for example, Cu(NO3)2·3H2O, Ni(CH3COO)2·4H2O, Co(CH3COO)2·4H2O, Mn(CH3COO)2·4H2O and obtained three metal complexes by using the natural evaporation method. HL2 and its corresponding Cu(II), Ni(II), Co(II), Mn(II) complexes were analyzed using IR, UV-Vis, and emission spectroscopy, elemental analysis and single-crystal X-ray crystallography. The spectroscopic data of the Cu(II), Ni(II), Co(II), Mn(II) complexes were compared with the ligand HL2. The electrochemical properties of the metal complexes were determined by cyclic voltammetry. In addition, SOD-like activities of HL2 and Ni(II) complex were also investigated. The geometries and electronic properties of both the ligand HL2 and the metal complexes were studied by DFT calculation. Moreover, the calculated HOMO and LUMO energies show the character of the ligand HL2 and the metal complexes.4. Urea derivatives with coumarin ring were designed and synthesized, mutiple series of substituted asymmetric semicarbazides were synthesized by reactions of cinnamoyl isocyanate, which was prepared from cinnamoyl azide by Curtius rearrangement, with acid hydrazides under microwave irradiation using a one-pot procedure. Compared to conventional methods, this method has the advantages of mild conditions, easy handling, and high yields. The products have been characterized by analytical and spectral(IR and 1H NMR) data. N-(coumarin-3-yl)-N′-(2-amino-5-phenyl-1, 3, 4-thiadiazol-2-yl) urea of the crystal structure has been determined by single-crystal X-ray diffraction. DMSO is one of the most powerful readily available organic solvents. The structure of the DMSO molecule is a trigonal pyramid in shape. A self-assembling 3-D supramolecular structure is formed through intermolecular hydrogen bonds and π···π stacking interactions. Moreover, the compound emits strong fluorescence in blue region having abnormally high Stokes shifts.5. Four new Schiff base ligands with coumarin ring were designed and synthesized, also the recognition of various metal ions was studied. Heterocyclic schiff base type compounds with coumarin ring and other through the nitrogen atoms from carbon-nitrogen double bond and the adjacent a lone pair electrons oxygen and sulfur atoms chelate with metal ions, play significant roles in the synthesis, structure and interaction between metal ions and schiff base ligands, improving investigation for the mechanism of the biological activity and stability. Hopefully, these receptors show a fine prospect of application in the analysis and detection of specific heavy metal ions.6. Optimized geometries and corresponding molecule orbitals(MOs) energy for the ligand HL1, HL2, and cobalt(III), copper(II), zinc(II), nickel(II), cobalt(II), manganese(II) complexes were carried out using the Density Functional Theory method at the B3 LYP level using Gaussian 09 program package with the aid of the Gauss View 5.0 visualisation program. With the aid of theoretical calculation, the geometries of the metal complexes were optimised in singlet state by the DFT method with the B3 LYP correlation function. Vertical electronic excitations based on the DFT-B3 LYP optimised geometry were calculated using the Time-Dependent Density Functional Theory(TD-DFT) formalism in CH2Cl2 using conductor-like polarisable continuum model(CPCM). Multiwfn program was used to calculate the fractional contributions of the ligand to zinc(II) and manganese(II) complexes. The TDDFT calculations have been done on the optimised geometries to understand the electronic structure and spectral transition in the ligand and the metal complex. To understand the electronic structures of the ligand HL1, HL2 and the metal complexes Density Functional Theory(DFT) calculations have been carried out and for better understanding of the electronic transitions TDDFT calculations have been done on the DFT optimised geometries. The energy and compositions of some selected molecular orbits for the ligand HL1, HL2 and the metal complexes are summarised.