Syntheses, Structures and Properties of the Coordination Polymers Based on1,10-phenanthroline Derivatives Ligand
|Course||Clean energy and environmental protection|
|Keywords||Coordination Polymers 1,10-Phenanthroline Derivatives Anionic Crystal Structure Adsorption|
The design of coordination polymers is not only because of their charming structure, but also has potential applications in optical, electricah magnetic. So the researchers have synthesized an increasing number of new coordination polymers. However, the property of the coordination polymer is dependent on its crystal structure. Each polymer has its unique property. Accordingly, to control the structure and dimension of the coordination polymers is very important. Therefore, in this paper, we explore an effective method to control the structure.The first part, we have selected the rigid2-(4-methoxyphenyl)-imidazo[4,5-f][l,10]phenanthroline(MOPIP) as neutral ligand, the2,5-pyridine dicarboxylic acid,2,6-pyridine dicarboxylic acid,2,3-pyridine dicarboxylic acid,1,3-benzenedicarboxylic acid and1,4-benzenedicarboxylic acid as the bridge ligands. Eight novel transition metal coordination complexes [Cd2(MOPIP)2(2,5-pydc)2]n (1),[Cu2(MOPIP)2(2,5-pydc)2]·H2O (2),[Mn(MOPIP)2(2,5-pydc)]·3H2O (3),[Cd(MOPIP)2(2,6-pydc)]·3H2O (4),[Cd2(MOPIP)2(2,3-pydc)2·H2O]n (5),[Co(1,3-bdc)(MOPIP)2·H2O]·H2O (6),[Pb(1,3-bdc)(MOPIP)2]n·H2O (7) and [Pb(1,4-bdc)(MOPIP)]n (8) have been hydro thermally synthesized. By changing the position of the carboxyl group, the structure of coordination polymers can be changed from two-dimensional network(1), zero-dimensional configuration(4) to one-dimensinal chain(5). The coordination number and geometry of the metal ion can be different, such as:seven-coordinated pentagonal bipyramidal geometry(7)、 six-coordinated pentagonal pyramidal geometry(8), owing to the different position of the carboxyl group. To control the metal center, we can get the coordination complexes with different nuclear structure, such as dinuclear(2), mononuclear(3), and different dimension just as zero-dimensional configuration(6), one-dimensional zigzag chain(7).The second part, we have selected the rare earth ions as metal center, possessing a conjugate group MOPIP as ligand,1,3-benzenedicarboxylic acid and1,4-benzenedicarboxylic acid as the bridge ligands. Nine novel rare earth metal coordination polymers [Eu(1,3-bdc)1.5(MOPIP)]n·1/2nH2O (9),[Sm2(1,3-bdc)3(MOPIP)2]n·nH2O (10),[Nd2(1,3-bdc)3(MOPIP)2]n·nH2O (11),[Pr2(1,3-bdc)3(MOPIP)2]n·nH2O (12),[Ce2(1,3-bdc)2(1,3-Hbdc)2(MOPIP)2]n·3/2nH2O (13),[Gd2(1,3-bdc)3(MOPIP)2]n·nH2O (14),[Gd(1,4-bdc)1.5(MOPIP)]n (15),[Yb(1,4-bdc)1.5(MOPIP)]n (16) and [Sm(1,4-bdc)1.5(MOPIP)]n (17) have been synthesized. The influence of the metal ion of the same cycle to construct the different structure is small. So, the complexes (9)-(12) and (14), complexes (15)-(17) are isomorphous. The transition of the structure from one-dimensional chain (14) to six-connected three-dimensional network with (412-63) topology (15) is achieved by changed the position of the carboxyl group. Fluorescence analysis shows that the fluorescence of rare earth coordination polymers has been enhanced, owing to the addition of the conjugated MOPIP ligand. The electrochemical activity center of complex (9) is the central ion Eu(Ⅲ). The electrochemical process is one-electron redox process.The third part, we chose the2-methyldipyrido[3,2-f:2’,3’-h]quinoxaline (MEDPQ) as new ligand,2,5-pyridine dicarboxylic acid,1,3-benzenedicarboxylic acid and1,4-benzenedicarboxylic acid as the bridge ligands. Four novel transition metal coordination complexes [Cd(2,5-pydc)(MEDPQ)]n (18),[Cd(1,3-bdc)(MEDPQ)]n·2nH2O (19),[Co(1,3-bdc)(MEDPQ)]n·2nH2O (20) and [Pb2(1,4-bdc)2(MEDPQ)2]n·nH2O (21) were obtained under hydrothermal condination. By changing the neutral ligand, the three-dimensional structure of the complex (18) is different to that of the complex (1). The structure can be changed from grid-like structure (18) to a ladder-like structure (19) by changed the organic carboxylic acid. We also examined the chelating ability of the MEDPQ ligand. We modified the hydrogel with the MEDPQ to remove the metal ions Cu(Ⅱ) in water. The result shows that the hydrogel modified by MEDPQ ligand has a good adsorption to Cu(II) ions. That is also provided a method for the design of a new type hydrogel absorbent, which can be applied to adsorb and remove the heavy metal ions in waste water. It also has a positive significance for the prevention of water pollution and environment protection.