Urothermal Synthesis, Structure And Characterization Of Functional Coordination Polymers

Designing and synthesizing metal-organic coordination polymers of their potential application in the catalysis, gas storage, optics, electricity and magnetism have been the hot research field in coordination chemistry and material chemistry. The synthetic methods play an important role in the metal coordination polymer self-assembly process. Here, an urothermal synthesis based on the use of various urea derivatives as solvents has been used for synthesizing a variety of metal coordination polymers. The urothermal synthesis derives from the conventional solvothermal synthesis.Nine metal-organic coordination polymers with novel structre have been synthesized by the urothermal method. The structures of all coordination polymers have been determined by X-ray diffraction. Some of these coordination polymers have been characterized by element analysis, XRD, TGA, solid fluorescence and gas adsorption. They can be divided into two groups according to solvent used:I. Metal coordination polymers based e-urea {Zn3[(sip)2(temdpy)2(e-urea)4(H2O)2](e-urea)}n (1) [Zn(HFPPB)(e-urea)]n (2) [Cd2(5-Hisp)2(e-urea)2]n (3) [Cd(5-Nisp)(e-urea)]n (4) [Cd2(2-Abdc)2(e-urea)2]n (5) [Cd(BDC)(e-urea)]n (6) {[Cd3(BTC)2(e-urea)4](e-urea)2}n (7) [Mn(BTC)CI(e-urea)3]n (9)II. Metal coordination polymers based DMPU [Cd(HBTC)(DMPU)2]n (8)Complex 1 is a one-D chain with ladder-like structure, complex 2 is a one-D complex with double-chain, and complex 9 is two-D layer. Such three complexes were connected to three-D net work through rich hydrogen bonds provided from solvent of e-urea.Four novel complexes, complexes 3,4,5 and 6 were obtained by the assembly reactions of Cd salt with corresponding ligand under urothermal condition. Interes-tingly, such four complexes were connected to three-D net work with one-D metal chains. In these complexes, contain one-D channels in framework blocked by coordinational solvent.The self-assembly of cadmium with 1,3,5-Benzene-tricarboxylic acid in different solvent of urea derivatives under the same condition, we got two type complexes:complex 7 and complex 8. Complex 7 was a 3D network with trinuclear cadmium units as secondary building units (SBUs). Solvent of e-urea has three patterns in complex 7:containμ2-O connected with metal; terminal ligand in coordination; noncoordinated ligand in pore space. We also studied property of gas adsorption of complex 7. Noncoordinated solvent molecules were removed after the crystallization to generate porosity. The N2 and CO2 sorption studies on 7 at 77K and 273K reveal the Langmuir surface area of 7 was 35.56 m2 g-1 and The maximum CO2 uptakes of 7 was 17.5 cm3 g-1.Complex 8 is two-D layer. The fluorescence properties of complexes 1,3,5,7 have been studied.As demonstrated by these complexes, e-urea as solvent has several advantages. The most important one is the integration of four different roles:(1) as solvent dissolve precursor, (2) as a terminal ligand, (3) extra-framework noncoordinated ligand which is useful for the generation of additional pore space, (4) provide rich hydrogen bonds involve in building the framwork. Demonstrating the urothermal method was great potential method for the development of novel crystalline solids.