Construction,Magnetic And Fluorescent Sensing Properties Of Novel Metal-triazole Coordination Frameworks

During the last two decades,rational design and syntheses of novel coordination frameworks have attracted much interest due to their promising applications for gas storage/separation,catalysis,luminescence,drug delivery,sensors and magnetic materials.Generally,the preparation of such MOFs can be influenced by many factors,such as the nature of organic ligands,the crystallization conditions,metal/ligand ratio,reaction solvent system and so onAccording to above,the main contributions in this work are blow:1.A new flexible multi-dentate 1-(4-aminobenzyl)-1,2,4-triazole(abtz)ligand has been designed and synthesized,a series of two-dimensional(2D)triazole-functionlized metal-organic frameworks have been isolated.Firstly,when abtz and corresponding cadmium(?)salts are employed,the new rectangular-grid 2D coordination frameworks containing free ClO4-or SiF62-anions,1 and 2 can be isolated.Further in 1 weakly H-bonded ClO4-anions present within the voids can be partly exchanged by HSO4-anions to generate the anion exchanged crystalline product 3 in single-crystal-to-single-crystal(SC-SC)manner.On the other hand,1 can be used as a precursor to react with NH4NCS to obtain the 2D bilayer framework 4 under hydrothermal conditions.This also presents a novel example of structural transformation with bond rupture/formation from a mono-layer framework 1 to a 2D bi-layer framework 4.Further when AgClO4 is used to replace Cd(ClO4)2 in the reaction system,another 2D layer framework 5 with unique(2,4,5)connected topology can be isolated.The solid state luminescent properties and PXRD patterns of 1-5 have been investigated.Additionally,luminescent measurements illustrate that complexes 4 and 5 represent the novel examples as luminescent probes of new sensing materials.4 shows highly sensitive response to acetone and Fe3+.Besides,5 is the first report of multidimensional polymers based on triazole derivatives as luminescent response to small biological molecules such as vitamin C in the water solutions.2.A flexible multi-dentate trans-4,4'-azo-1,2,4-triazole(atrz)ligand has been employed,a series of novel coordination polymers have been isolated.6 and 7 present 1D polymorphic iron(II)-triazole frameworks,in which bicycle-pedal motion in the azo moieties of atrz can be observed.While 11 presents a 3D cation Cull nano-porous framework with dimensionality of 11.709(1)A×12.201(1)A.Interestingly,11 exhibits guest induced single-crystal-to-single-crystal(SC-SC)structural transformation to obtain the dehydrated compound 12,which presents another 3D nano-porous framework with dimensionality of 11.621(6)A×16.674(1)A.13 presents a 2D cation Cu? framework constructed by infinite zigzag(CuO)n chains and unique ?4-bridging atrz ligands.Further when Zn(NCS)2 is used in the reaction system,14 can be isolated which exhibits guest induced SC-SC transformation to obtain the dehydrated compound 15,accompanied by a color change from red(14)to pale pink(15).Variable temperature magnetic susceptibility reveals weak anti-ferromagnetic interactions between the central Iron(II)ions for 6-10.Anion exchange experiment indicates an anion-induced structural transformation from the 3D Cu? framework 11 to the 2D Cu? framework 13 confirmed by PXRD patterns.