| China is one of the six biggest lead reserves countries all over the world.Lead plays an important role in the battery,cable shield,alloy,X-ray sheath and catalyst industries.However,it is also a heavy metal which is harmful to human health.Most of lead in environment will transfer into the soil.Hence,it becomes a popular problem to treatment the soil lead pollution.At present,the most promising method is chelate-assist phytoextraction in soil.Here we studied the coordination modes of lead ions with the aminopolycarboxylatechelating agents:ethylenediaminetetraacetic acid,1,3-propanediaminetetraacetic acid and low molecular organic acid ligands:citric acid.Moreover,we investigated the solubleness and stablilities for the products by full characterizations of them.The results are significative to make the chelate-assist phytoextraction strategy in the view of coordination chemisty.Besides,we use the ethylenediaminetetraacetic acid chelate with lanthanide and the other doped metal ions to construct a series of novel complexes which make a contribution to metal organic framework materials.Here a series of complexes 1?22 have been synthesized:[Pb2?edta??H20?]2n?1?,[Pb4?edta?2]n-2nH20?2?,Pbn[Pb?edta?Pb?H2O?Cl]2n·2nH2O?3?,Pbn[Pb?edta?Pb?H2O?Br]2n·2nH2O?4?,{K4[Pb2?1,3-pdta?2]·6H2O}n?5?,{[Pb?1,3-H2pdta??H2O?]·2H2O}n?6?,{[Pb2?1,3-pdta??H2O?4]-4H2O}n?7?,[Pb2?1,3-pdta??H2O?2]n?8?,[Ca?1,3-H4pdta??N03?2?H20?2]n?9?,[Ca?1,3-H2pdta?]n·nH2O?10?,K4n[Ca2?1,3-pdta?2]n·2nH2O·2nCH3OH?11?,[?Pb2Hcit?2?C2O2?]n?12?,[K?H2O?]n[Pb?Hcit??H2O?]n·nH2O?13?,[Pb2cit]n?14?.[Ca?H2O?3]2n[Laedta?H2O?]2n·2nCl·2nH2O?15?,[Sr?NO3??H2O?2]n[Laedta?H2O?3]n·nH2O?16?,[Ba?NO3??H2O?2]n[Laedta?H2O?3]n·1.5nH2O?17?,Na12n[Laedta?SO3?]4n·8nNaCl·4nH2O?18?,[La?H2O?4]2n[Coedta?H2O?]3n·12nH2O?19?,[La?H2O?4]2n[Mnedta?H2O?]3n·12nH2O?20?,[Ce?H2O?4]2n[Mnedta?H2O?]3n·12nH2O?21?,[Pr?H2O?4]2n[Mnedta?H2P?]3n·2nH2O?22??The main results are summarized as follows:1.The reaction of ethylenediaminetetraacetic acid with Pb?NO3?2 resulted in complexes 1?4.With the comparison of synthesis,we found that EDTA seems not suitable for solubilizing lead with the existence of halide and low pH.The optimal condition is in the neutral solution which offers some theoretical basis in coordination chemistry for the chelate-assist phytoextraction strategy.2.The reaction of 1,3-propanediaminetetraacetic acid with Pb?NO3?2 resulted in complexes 5?8.The results show that pH = 9.0 is the optimal condition for 1,3-PDTA to solubilize lead.The soluble product complex 5 can convert to insoluble products 7 and 8 in suitable conditions.It deals with the problem where occurred in the use of EDTA that the soluble products will lanch to environment lead to secondary pollution.This is the first studied of lead 1,3-propylenediaminetetraacetates research.It is noteworthy that complex 7 may potentially apply in the selective adsorption of methanol due to its unique 5.2 A pore and?H2O?26 water cluster.3.The research of the competitiveness of lead and calcium ions in chelating with 1,3-propanediaminetetraacetic acid resulted in complexes 9?11.The ligands will coordinate to calcium ions in pH = 5.0?8.0.4.The reaction of citrit acid with Pb?NO3?2 resulted in complexes 12?14.Citrit acid has not as strong coordination ability as aminopolycarboxylic acids which lead to the low yield of lead?II?citrates.The systhesis suggest that alkaline-earth metals such as potassium and sodium can solubilize lead in neutral condition which may improve the lead absorbtion of plants.5.The reaction of ethylenediaminetetraacetic acid with lanthanide and alkaline earth metals,transition metals or inorganic molecules resulted in complexes 15?22.The stabilities of complexes are increasing whih the improve of the alkaline earth metallic radius.The lanthanide contraction is owersed in comparison of the bond distances in complexes 19?22. |
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