Cyanocomplexes with one-dimensional structures: preparations, crystal structures and magnetic properties

We report a conceptually new method for the synthesis of Prussian blue (PB) nanoshells with tunable size using miniemulsion periphery polymerization (MEPP). The process of MEPP involves the preparation of miniemulsion droplets using organometallic surfactants, followed by a coordination polymerization at the periphery of the droplets. The organometallic polymers with nanoshell structure were confirmed by using FT-IR, UV−vis, TEM, SEM, and AFM. WAXD measurements indicated that the shell structure suppressed the crystallization of the polymers. We also discovered that the nanoshell structure can significantly enhance the thermal stability of the materials. The hollow structures plus inherent magnetic properties of PB render the materials potential useful as multifunctional capsules.

Synthesis and Characterization of Organometallic Coordination Polymer Nanoshells of Prussian Blue Using Miniemulsion Periphery Polymerization (MEPP)

A series of new heterometallic coordination polymers has been prepared from the reaction of metal−ligand cations and KAg(CN)2 units. Many of these contain silver−silver (argentophilic) interactions, analogous to gold−gold interactions, which serve to increase supramolecular structural dimensionality. Compared to [Au(CN)2]- analogues, these polymers display new trends specific to [Ag(CN)2]-, including the formation of [Ag2(CN)3]- and the presence of Ag···N interactions. [Cu(en)2][Ag2(CN)3][Ag(CN)2] (1, en = ethylenediamine) forms 1-D chains of alternating [Ag(CN)2]- and [Ag2(CN)3]- units via argentophilic interactions of 3.102(1) A. These chains are connected into a 2-D array by strong cyano(N)−Ag interactions of 2.572(3) A. [Cu(dien)Ag(CN)2]2[Ag2(CN)3][Ag(CN)2] (2, dien = diethylenetriamine) forms a 1-D chain of alternating [Cu(dien)]2+ and [Ag(CN)2]- ions with the Cu(II) atoms connected in an apical/equatorial fashion. These chains are cross-linked by [Ag2(CN)3]- units via argentophilic interactions of 3...

Heterobimetallic Coordination Polymers Incorporating [M(CN)2]- (M = Cu, Ag) and [Ag2(CN)3]- Units: Increasing Structural Dimensionality via M−M‘ and M···NC Interactions

Reaction of a Langmuir monolayer of an amphiphilic pentacyanoferrate(3+) complex with Ni(2+) ions from the subphase results in the formation of a two-dimensional iron-nickel cyanide-bridged network at the air-water interface. The network can be transferred to various supports to form monolayer or multilayer lamellar films by the Langmuir-Blodgett (LB) technique. The same network does not form from homogeneous reaction conditions. Therefore, the results demonstrate the potential utility of an interface as a structure director in the assembly of low dimensional coordinate covalent network solids. Characterization of the LB film extended networks by X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy, SQUID magnetometry, X-ray absorption fine structure (XAFS), and grazing incidence synchrotron X-ray diffraction (GIXD) revealed a face-centered square grid structure with an average domain size of 3600 A(2). Magnetic measurements indicated that the network undergoes a transition to a ferromagnetic state below a T(c) of 8 K.

Supramolecular assembly at interfaces: formation of an extended two-dimensional coordinate covalent square grid network at the air-water interface.

Substitution of the weakly binding aqua ligand in [Cu(tren)OH2]2+ and [Cu(tpa)OH2]2+ (tren = tris(2-aminoethyl)amine; tpa = tris(2-pyridylmethyl)amine) by a cyano ligand on ferricyanide results in the assembly of heteropolynuclear cations around the cyanometalate core. In water, the reduction of the FeIII core to FeII generates complexes that feature heteropolycations in which ferrocyanide is encapsulated by the CuII moieties:  [{Cu(tpa)CN}6Fe][ClO4]8·3H2O 1, [{Cu(tren)CN}6Fe][ClO4]8·10H2O 2, [{Cu(tren)CN}6Fe][Fe(CN)6]2[ClO4]2·15.8H2O 3, and [{Cu(tren)CN}6Fe][{Cu(tren)CN}4Fe(CN)2][Fe(CN)6]4·6DMSO·21H2O 4. The formation of discrete molecules, in preference to extended networks or polymeric structures, has been encouraged through the use of branched tetradentate ligands in conjunction with copper(II), a metal center with the propensity to form five-coordinate complexes. Complex 3 crystallizes in the monoclinic space group P21/c (#14) with a = 14.8674(10), b = 25.9587(10), c = 27.5617(10) A, β = 100.8300(10)...

The encapsulation of ferrocyanide by copper(II) complexes of tripodal tetradentate ligands. Novel H-bonding networks incorporating heptanuclear and pentanuclear heterometallic assemblies.

Xiu-ying Zhang

Papers

The design, assembly, properties and crystal structure of one-dimensional polymeric cyanide-bridged nickel(II):nickel(II) complexes