Syntheses, Structures And Properties Of Heterometallic Cyano-bridged Coordination Framework With Microporous Frameworks

There are a lot of weak intermolecular interactions play a key rolefor the molecular recognition, self-assembly and crystallizationprocess, except for coordination bonding and strong hydrogenbonding. However, the origin, strength, or even existence of suchinteractions is highly controversial. With the large number ofsupramolecular system and the crystal structure have been reportedand theoretical research, it was found that the supramolecularinteraction not only affect the supramolecular structure but also cansignificantly change the various physical and chemical properties ofthe system. Unfortunately, how to test the nature of the interactionand energy have still been problem. As for cuprous cyanidesupramolecular isomers, people found that cyanide can be assembledinto zero to three dimensional structures, however, heterometalliccyano-bridged open framework with high dimension are less reported.For this reason, we have synthesized a series of heterometalliccyano-bridged open framework supramolecular isomers byintroduced various auxiliary ligand. Moreover, some argued problemssuch as Cu^I···Cu·Iweak interactions, template effect, chelate effect and supramolecular isomerism have been explored. The main resultsare as follows:1. In view of various coordination modes of Cu center, we havesuccessfully synthesized two3D pseudopolyrotaxane supramolecularisomers of [Cu₂（pyz）（CN）₂]·[CuCN]（1and2） under hydrothermalconditions by changing cyanide source and reaction temperature.Supramolecular isomer1is the first example unprecedentedShubnikov-type （5,34） sheets, which consists of linear, trigonal, andtetrahedral Cu（I） atoms and these sheets are penetrated by [Cu（CN）]∞chains via unsupported Cu^I···Cu·Iinteractions. In contrast, the[Cu₂（pyz）（CN）₂] sheets in isomer2can be viewed as a classical（6,3）-topological brick wall layer, which are also penetrated by[Cu（CN）]∞chains in the absence of cuprophilicity. Under thehydrothermal nonequilibrium crystallization conditions, the differentreleases of cyanide via hydrolysis of environmentally friendlyK₃[Fe（CN）₆] and K₄[Fe（CN）₆] may play a crucial role in the formation ofdifferent supramolecular isomers. Interestingly,1and2show strongphotoluminescence related to the various local coordinationgeometries of copper atoms and weak cuprophilic interactions.2. Chemical replication of Cairo tiling is of much interest because itrepresents a marriage between chemistry and art. By usingenvironmentally friendly K₂[Ni（CN）₄] as cyanide source, three newheterometallic cyano-bridged mixed-valence CuI/CuIIcoordinationpolymers with d8-d10three different electronic configurations,[Cu-2Ni（CN）₅（H₂O）₃]（3）,[Cu₂Ni（CN）₅（pn）H₂O]（4）, and [Cu₃Ni（CN）₆（pn）₂]（5）（pn=1,2-propane diamine）, have been synthesized by gradualincrease of the amount of pn. The water molecules located in meridianal positions of the octahedrally coordinated Cu（II） atom canbe replaced by chelate pn group, leading to three-connected T-shapednode and linear [Cu（NC）2（pn）2] unit, which further influence thechange of structures. Assembly of trigonal, T-shaped, andsquare-planar nodes in1:1:1ratio via cyanides resulted in2D （5,34）Cairo tiling sheets in3and4, while connection of trigonal andsquare-planar nodes in2:1ratio via cyanides and [Cu（NC_）2（pn）₂] unitsgenerated unprecedented3D twofold interpenetrated net in5. Thiswork clearly shows that chelate effect can be one of the importantfactors to affect the supramolecular structures of metal coordinationnetworks. Besides closed-shell Cu（I） atoms, the Ni（II） atoms with d8configuration also are diamagnetic. The antiferromagnetic couplingdominating by Cu（II） atoms.3. Crystallographic evidence for close Cu^I···Cu·Iinteractions is oftenambiguous because of bridging ligands or electrostatic interactions.Hence, we have successfully obtained two heterometalliccyano-bridged supramolecular isomers with unsupported Cu^I···Cu·Iinteractions [（H₂O）-4Cu₂Ni（CN）₄]（6and7） under hydrothermalcondition by controlling reaction temperature. The supramolecularisomers6and7possess identical chemical compositions andsimilar pentagonal [Cu₂Ni（CN）₄] ribbon, but the15-membered[Cu（1）₂Cu（₂）₂Ni（1）（CN）₅] ring of7is a little distorted. The pentagonalribbons are extended via Cu^I···Cu·Iinteractions into a double layerframework in6and7. It needs to be mentioned that compound7contains two types of Cu^I···Cu·Iinteractions with identical distance2.736, which has littler shorter than only2.835in compound6.The minor different may be responsible for similar supramolecular arrays for the whole framework. The Cu^I···Cu·Iinteractions is notassociated with ligand-bridged, hydrogen-bonded, electrostatic-attracted, or π-π stacked effects, indicating genuine unsupportedCuI···CuIcontacts. Meanwhile, separable isomers6and7, asconfirmed by powder X-ray diffraction patterns. The two isomersdisplayed similar magnetic properties related to their identicalchemical composition. The compound [（H₂O）3Cu3（CN）5]（8） exhibitsmixed-valence CuI/CuIIcoordination polymers with supportedCuI···CuIcontacts. Variable-temperature magnetic susceptibilitymeasurements reveal antiferromagnetic coupling in threecompounds.4. By using environmental friendly K₃[Co（CN）₆]] or K2[Ni（CN）4] as acyanide source, hydrothermal reactions of CuCl2and differentamines ligands resulted in one monometallic and13heterometalliccyano-bridged open frameworks supramolecular isomers, namely[Co（Hpip）（H₂O）2Co（CN）₆]（9）,[H₂me2pip][Cu₂Co（CN）₇]（10）,[H₂DABCO][H₂O][Cu₂Co（CN）₇]（11）,[HNH3·H₂O]₂[Cu₂Co（CN）₇]（12）,[H₂dmpa][Cu₂Co（CN）₇]（13）,[H₂O]4[（Pyz）Cu₂Co（CN）₆]（14）,[H₂dmpa][Cu₂Co（CN）₆]（15）,[Hmeim][Cu₂Co（CN）₆]（16）,[H_1.5DABCO]₂[Cu3Co2（CN）12]（17）,[（Hpyz）（H₂O）0.5Cu₂Co（CN）₆]（18）,[（tta）₅Cu₄Co（CN）₆]（19）,[N（CH3）4][Cu2Ni（CN）5]（20）,[N（CH3）4][CuNi（CN）4]（21）,[N（C4H9）4][Cu2Ni（CN）5]（22）. Thesesupramolecular isomers contain seven known topology and fiveunknown topological structures. Firstly, the different types oforganic diamines ligand as template or linker play a crucial role inthe formation of9-19products: from uninodal nets, dinodal nets,trinodal nets to tetranodal nets. Compound9shows monometallic 2D Shubnikov tetragonal plane net. The compounds10-19are Cu/Coheterometallic cyano-bridged open framework supermolecularisomers. All compounds10,11,12,13, and14show3-D binodal（4,6）-connected open frameworks constructed by4-connected Cucenter and6-connected Co center, in which the node ratio of4-connected to6-connected is2:1. Isomorphic10,11, and12showfsh-like archetypes. Complex13shows FeS2-like archetype.Compound14shows an unprecedented topological framework viapyrazine as linker. Complex15and16show3-D （3,6）-connectedpyr-like and rtl-like archetype, respectively, in which ratio of3-connected node to6-connected nodes is2:1. Complex17shows a3-D trinodal （4,6,6）-connected bixbyite-like open networkconstructed by4-connected Cu center and two types of6-connected Co center with ratio of6:1:3. Complex18shows anunprecedented （4,4,6）-connected open framework with{4⁴.5⁶.6².7².8}{4⁴.6²}{5⁴.6.8} topology. The only example19shows anunprecedented {3¹⁰.4¹⁶.5¹⁶.6³}{3³.4⁷.5⁴.6}{3⁴.4¹⁰.5⁶.6}2{4¹².6³}topological tetranodal （6,6,7,10）-connected open framework. Inaddition, the compounds20,21, and22are Cu/Ni heterometalliccyano-bridged open framework supermolecular isomers via tuninginorganic ammonium cation as template. Various inorganicammonium cations are responsible for the structural change from2D layer to3D open framework. Complex20shows anunprecedented （3,4）-connected2D sheet. Complex21shows a3-D（4,4）-connected PtS-like open network. Complex22shows anunprecedented （3,4,4）-connected open framework with{6.7²}4{6².7².10²}{7².8².10²} topology, in which ratio of two types of 4-connected nodes to6-connected nodes is4:1:1. In addition, herein,we report the structural analysis and SEM-EDS properties of allthese complexes and the thermogravimetric analyses of thecomplexes10,11,12,14,15, and17. Interestingly, compound14show high selectivity adsorption for CO₂over N₂and H₂at273K.