Coordination polymers channels

S. Subramanian, M. J. Zaworotko, "Porous solids by design IZn(4,4 -bpy)2(SiF6)]n-xDMU a single framework octahedral coordination polymer with large square channels , Angew. Chem, Int. Ed. Engl 1995,34,2127-2129. 

Belcher, W. J., Longstaff, C. A., Neckenig, M. R., Steed, J. W., Channel-containing ID coordination polymers based on a linear dimetallic spacer. Chem. Commun. 2002, 1602-1603. 

The same group also explored the reactivity of the two asymmetric dithioether ligands with cyclohexyl (L45) and phenyl (L46) end groups toward Cul.164 Reaction of 2 (cyclohexylmethylthio)-l-thiomorpholinoethanone L45 with copper(I) iodide afforded a ID channel-type coordination polymer [Cu4I4(L45)2]n 45, interconnected by cubane-like tetranuclear Cu4I4 cluster units (Scheme 24). The mean Cu-Cu distance within the cluster cubes amounts to 2.749 A at 173 K. 

Figure 34 Cross-linking of Ni(p,-SCN)2L2 n coordination polymer via carboxyl-carboxyl hydrogen bonds between isonicotinic acid ligands (L) to give a sheet structure which stacks providing channels that can accommodate polycyclic aromatic hydrocarbon guest molecules, here anthracene [80], Oxygen, nitrogen and key hydrogen atoms are shaded nickel thiocyanate polymer and anthracene guest molecules shown in wireframe style.

Several functional properties can be expected from the materials of coordination polymers owing to their extended nature and high thermal stability and the existence of cavities and channels. Here we describe some of the properties that have been explored using above-described layered structures. 

Bilayer architectures formed in M2(2)3(N03)4 n (where M = Co, Ni and Zn) were one of the first systems of coordination polymers to be shown as porous materials [43]. The bilayer architectures interdigitate with each other leaving small channels in the crystal lattice which were occupied by solvated water molecules. Powder X-ray studies indicate that the water molecules can be removed from the network without causing any distortion or decomposition of the network. The adsorption studies of water removed and dried sample indicated that the material is capable of adsorbing CH4, N2 and 02. About 2.3 mmol of CH4 and 0.80 mmol of N2 or 02 are adsorbed per gram of anhydrous material. The adsorption-readsorption followed the same isotherm, indicating the stability of the network throughout the process. Further, the isotherms for the adsorption-readsorption can be classified as type I in the IUPAC classification [48]. 

These principles of crystal engineering and supramolecular synthesis have thus far been used to design, isolate, and characterize network structures from relatively small molecular components. In the context of coordination polymer networks, a recent review indicates how wide the range of chemical components and accessible network motifs has become.48b However, the scale of these structures is such that cavities and channels are on the order of 1 nm and, to date, each cavity is identical. Careful selection of appropriate substrates or components and ever more control over crystal packing will offer the potential for rational design of an even more extensive array of modular (i.e. binary, ternary, or even higher order) structures than those that are currently available. In particular, judicious choice of supermolecules... 

Figure 3.16 The structure of [Tb(bpdc)i 5(H2O)] 0.5nDMF. (a) The paddle-wheel building block, (b) The 3D-framework showing the large rhombic channels (Tb, black O, grey C, white H, omitted DMF guest molecules in (b) have been removed for clarity). (Redrawn from the CIF file of X. Guo et al., Synthesis, structure and luminescent properties of rare earth coordination polymers constructed from paddle-wheel building blocks, Inorganic Chemistry, 44 (11), 3850-3855, 2005 [75].)...

Chen and coworkers have reported that a series of multidimensional porous polymers with 3d f mixed metals could recognize some specific cations. For example, two 3d-4f het-erometallic coordination polymers ([Ln(L15)3Mni.5(H20)3]-3.25 HyOlco [L15=pyridine-2,6-dicarboxylic acid Ln = Eu (Eu-15) Ln = Tb (Tb-15)] with ID-channels could recognize Zn + to some extent [38]. The emission intensity of Eu-15 gradually increased upon addition of... 

Zhao, B., Chen, X.Y., Cheng, R, et al. (2004) Coordination polymers containing ID channels as selective luminescent probes. Journal of the American Chemical Society, 126, 15394-15395. 

TMA can coordinate to not only Cu2+ to form the typical 3-D framework polymer but also to Co2+ to form a porous host-guest compound Co(TMA) (py) with a different structure. The guest pyridine molecules in this compound may be removed from the channels without the collapse of the framework, and the pyridine-removed porous material adsorbs other guest molecules.[187] Polymerization of TMA with a Ni2+ macro-cyclic complex leads to a porous coordination polymer with a unique structure. In the... 

The reaction of 4,4, 4"-benzene-l,3,5-triyltribenzoic acid (denoted BTB) and cop-per(II) nitrate in a mixed solvent of ethanol, DMF, and water at 65 °C for 1 d gives rise to an interwoven coordination polymer Cu3(BTB)2(H20)3 (DMF)9(H2O)2.[190] This compound possesses channels with a diameter of 1.6 nm (Figure 9.28), and the channels contain guest DMF and water molecules. Upon removal of the guest molecules, the compound exhibits excellent adsorption properties. 

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