| Metal-Organic Frameworks (MOFs) are a class of hybrid materials composed of metal ions jointed by a variety of organic ligands through strong non-covalent bonds. MOFs have the merits of the shape and size of the pores as well as they can be designed by ligand modification the organic ligands. They have shown high potential applications in diverse fields, such as gas adsorption, storage and separation, nonlinear optics, catalysis and biomedical applications.Recently, the applications of MOFs in the detection of biomolecules have received considerable attentions. Nevertheless for practical application, moisture stability and water solubility are the prerequisite for MOFs to be used in the basic in vivo environment. These requirments, however, moisture instability and water insolubility contrast the intrinsic characteristics of dominant amount of MOFs, and limit their further application.In this thesis, we synthesized three types of water-soluble quaternized carboxylates, and their corresponding 22 MOFs. We also investigated their activity for the recognition of HIV DNA. The obtained results are summarized below.Part 1:We synthesized a new zwitterionic dicarboxylic ligand of 1-(3,5-dicarboxybenzyl)-4,4’-bipyridinium bromide (H2dcbbBr) and isolated two-dimensional structure of {[Na(dcbb)(H2O)]}n (1). Then, we synthesized four water soluble copper(Ⅱ) complexes from the transmetalation reaction of complex 1 in the presence of 5-fluorouracil (5-FU), namely,{[Cu(dcbb)2(H2O)2]·10H2O}n (2), [Cu(dcbb)2]n (3),{[Cu(dcbb)2(H2O)][Cu(dcbb)2]2}n (4) and{[Cu2(dcbb)2(OH)2 (H2O)6]·2H2O}n (5). All these Cu(Ⅱ) complexes were characterized by IR, elemental analyses and single crystal X-ray crystallography. Amongst these four Cu(Ⅱ) complexes,1 and 3 show a two two-dimensional structure, whereas 2 is a one-dimensional structure, compound 4 is a cocrystal form of 2 and 3, compound 5 has a dinuclear structure. Among these complexes, compound 3 can be used as an efficient biosensor for the detection of HIV DNA with the quenching efficiency (QE%) towards the probe DNA approaching 61.8%, the recovery efficiency (RE) of 0.52 and the detection limit of 1.42 nM. These results indicate that complex 3 can be used as a sensing platform with good specificity for the detection of HIV ds-DNA in vitro.Part 2:Based on the results described in part one, in order to improve the moisture stability and water solubility of MOFs, we synthesized a quaternized zwitterionic tricarboxylic ligand, H3CbdcpBr (Cbdcp= N-(4-carboxybenzyl)-(3,5-dicarboxyl) pyridinium) and obtained polynuclear sodium salt-aggregate {Na3[Na9(Cbdcp)6(H2O)18]}n (6). We synthesized a family of water stable and soluble Zn(Ⅱ) complexes from the transmetalation reaction of 6, in the presence of aspirin, 5-fluorouracil (5-FU) or additional auxiliary ligands. Accordingly, we obtained twelve novel Zn(Ⅱ)-based coordination polymers, namely, {Na3[Na9(Cbdcp)6(H2O)18]}n (6) (3D),{[Zn5(Cbdcp)4(OH)2(H2O)8]}n (7) (2D), {[Zn2(Cbdcp)2(H2O)6]·2H2O}n (8) (ID), [Zn(Cbdcp)(H2O)3·H2O]n (9) (ID), {[Zn(bipy)(H2O)4](Cbdcp)·3H2O}n (10) (ionic complex), [Zn(Cbdcp)(pbz)(H2O)2]n (11) (1D),{[Zn(Cbdcp)(bpe)1/2·2H2O]}n (12) (3D),{[Zn(Cbdcp)(bpea)1/2]·2H2O}n (13) (3D),{[Zn(Cbdcp)(azopy)1/2·3H2O]}n (14) (3D),{[Zn(HCbdcp)2]·H2O}n (15) (2D),{[Zn(Cbdcp)(bpe)1/2]·2H2O}n (16) (2D),{[Zn(Cbdcp)(bpea)1/2]·2H2O}n (17) (2D) and{[Zn(Cbdcp)(azopy)1/2]·2H2O}n (18) (3D). Complexes 6,12,13,14 and 18 with 3D structure have the void volume, which is 1359.6 A3 (37.4%),549.4 A3(13.2%),429.7 A3(10.3%),322 A3(14.3%) and 550 A3(13.2%), respectively. All these Zn(II) complexes were characterized by IR, elemental analyses and single crystal X-ray crystallography. Amongst these complexes, compound 15 can be used for ds-DNA detection. The quenching efficiency (QE%) of compound 15 towards the probe DNA is 73.2% and the recovery efficiency (RE%) is 1.57 with a detection limit of 10 pM (S/N=3SD/k). These results indicate that compound 15 may form electrostatic,π-stacking, or hydrogen bonding interactions with probe DNA with its aromatic rings and the protonated free carboxylic acid groups. Compound 15 can thus be used as an effective fluorescent sensing platform for HIV ds-DNA detection and is capable of distinguishing complementary ds-DNA from mismatched target sequences, showing high selectivity and sensitivity.Part 3:Based on the previous two parts, we synthesized a zwitterionic tricarboxylic acid ligand N-carboxymethyl-(3,5-dicarboxyl)pyridinium) bromide (H3CmdcpBr) and its four moisture stable and water soluble zinc(II) complexes in the presence of auxiliary ligands 2,2’-bipyridine (2,2’-bipy),1,10-phenanthroline (phen) and 2-(4-pyridyl)benzimidazole (pbz), that is,{Zn(Cmdcp)(H2O)}n (19) (2D), {[Zn2(Cmdcp)(2,2’-bipy)2(H2O)5](NO3)2·3H2O}n (20) (ID),{[Zn(phen)(H2O)4] [Cmdcp]} (21) (ionic complex) and {[Zn(Cmdcp)(pbz)][pbz]·H2O}n (22) (2D). All these Zinc(II) complexes were characterized by IR, elemental analyses and single crystal X-ray crystallography. Amongst these complexes, compound 20 can be used as an efficient biosensor for the detection of HIV DNA. The quenching efficiency (QE%) of compound 20 towards the probe DNA is 65.7%, with the recovery efficiency (RE) been 0.99 and the detection limit of 7.4 nM. These results indicate that the sensing platform performs favorably with good specificity for the detection of HIV ds-DNA in vitro. We can further conclude that compound 20 can be used for HIV DNA detection with good specificity from the experiment of G4-DNA (G4-DNA as the mismatched target sequences). |
PDF Full Text Request