Coordination polymer

About: Coordination polymer is a research topic. Over the lifetime, 11988 publications have been published within this topic receiving 212219 citations.

A Combined Top‐Down/Bottom‐Up Approach for the Nanoscale Patterning of Spin‐Crossover Coordination Polymers

Abstract: Molecular spin-crossover complexes of 3d–3d transitionmetal ions have been the focus of many researchers’ work because of their fascinating properties associated with the bistability of their electronic states (high spin (HS) or low spin (LS)). Although the origin of the spin-crossover phenomenon is purely molecular, the macroscopic behavior of these systems in the solid state is strongly determined by the interactions, of mainly elastic origin, between the transition-metal ions. Recently, remarkable progress has been made in the area of spin-crossover complexes with infinite one-, two-, or three-dimensional (1D, 2D, 3D) networks, the so-called coordination polymers. The purpose of this approach was the enhancement and fine tuning of cooperative properties by the strong covalent links between the metallic centers in the polymers. Indeed, a number of highly cooperative polymer systems have been reported in the recent literature that display hysteretic behavior (thermal and piezo), in some cases even at room temperature. In addition to this, we have recently demonstrated that 3D coordination polymers represent an attractive platform for growth of surface thin films with spin-crossover properties. In fact, the 3D network structure allows the sequential assembly, via stepwise adsorption reactions, of multilayer films based entirely on intraand interlayer coordination bonds. These films have opened up possibilities for investigating size-reduction effects, optical and dielectric properties, and device applications of spin-crossover materials. A further step in this direction is the generation of microand nanometer-sized lateral patterns. In fact, the multilayer sequential assembly (MSA) process (also called directed assembly or layer-by-layer assembly in the literature) has become increasingly popular not only for fabricating thin films but also many efforts have been devoted to generating distinct patterns of the multilayer films. Various lithographic and nonlithographic methods—such as deposition on chemically patterned surfaces, inkjet printing, lift-off processes, etching, direct photopatterning, and microcontact printing—have been explored with this aim. Each method has, of course, different merits, but the lift-off process remains an industry standard owing to its simplicity and reliability. Furthermore, when combined with electron-beam lithography (EBL), it allows patterns to be obtained in a wide size range down to the sub10 nm limit, and the alignment of the patterns is also possible with respect to structures that may already exist on the substrate. In this Communication, we report on a process for nanoand microscale assembly of the 3D spin-crossover coordination polymer Fe(pyrazine)[Pt(CN)4] (1) (Scheme 1) by using a combination of top-down (lift-off) and bottom-up (MSA) methods. We call attention to the 3D polymer nature of this system, which is the key aspect for 1) obtaining room-temperature hysteresis, 2) assembling multilayers, and 3) performing C O M M U N IC A IO N

Tuning the Dimensionality of the Coordination Polymer Based on Polyoxometalate by Changing the Spacer Length of Ligands

Abstract: Through tuning the spacer length of flexible bis(triazole) ligands, three Keggin anion-based coordination polymers with different dimensionalities, [Cu4(H2O)4(bte)2(HPMoVI10MoV2O40)]·2H2O (1) (bte = 1,2-bis(1,2,4-triazol-1-yl)ethane), [Cu(btb)][Cu2(btb)2(PMo12O40)] (2) (btb = 1,4-bis(1,2,4-triazol-1-y1)butane), and [Cu5(btx)4(PMoVI10MoV2O40)] (3) (btx = 1,6-bis(1,2,4-triazol-1-y1)hexane), were synthesized and structurally characterized. Compound 1 exhibits a ladder-like chain, in which the polyoxometalate (POM) anions act as the “middle rails” of the ladder. The bte ligand with shortest spacer length acts as not only the bridging linker but also the chelator, which terminates the dimensional extension. Compound 2 exhibits a 2D POM-based framework, containing POM/Cu/btb grid-like layers. In compound 3, there exist three sets of (123)(121)2 2D Cu-btx frameworks to generate a 3-fold interpenetrating structure, into which the hexadentate POM anions are inserted to construct a 3D structure. The structural anal...

Monitoring Shape Transformation from Nanowires to Nanocubes and Size-Controlled Formation of Coordination Polymer Particles

Abstract: Infinite coordination polymers in which metal ions or metal clusters are connected bymolecular building blocks consisting of organic molecules or organometallic complexes have received a great deal of attention due to their useful applications in gas storage, catalysis, optics, recognition, and separation. Rationalization of their chemical and physical properties from structural studies is of fundamental interest in the field of coordination polymer materials. Similarly, microand nanostructured materials are essential in many different areas, such as catalysis, optics, biosensing, medical diagnostics, and data storage, and their size, shape, and composition are the key parameters that dictate chemical and physical properties. Recently, a synthetic strategy for the preparation of microand nanoparticles made from infinite coordination polymers has been demonstrated by several groups. This new class of materials promises to advance nanoparticle science into the realm of infinite coordination polymers, and thereby circumvent the nominal composition limitations generally ascribed to nanoparticles. Control of the composition of nanoparticles generated from functionally defined precursors is a promising research area due to the fundamental interest in materials that have practical applications in chemistry, biology, physics, and related interdisciplinary fields. Coordination polymer particles (CPPs) made from functional metalloligand building blocks have been shown to have a high degree of tailorability. The development and application of CPP materials requires an understanding of how the particles are formed, and the ability to control their size and shape. Herein we describe a solvothermal approach for the synthesis of CPPs made from transition-metal ions and metallosalen (salen= N,N’-bis(salicylidene)ethylenediamine) building blocks. We also describe an interesting nanoparticle wire-to-cube morphological transformation, and the utilization of this transformation process to control CPP formation. In a typical synthesis, fluorescent cubic nanoparticles were prepared by the following simple procedure (Scheme 1): carboxy-functionalized salen ligand N,N’-phenylenebis(salicylideneimine)dicarboxylic acid (1, 3 mg) was dissolved in DMSO (1 mL), and the solution was added to DMF (2 mL) containing two equivalents Zn(OAc)2. One equivalent of Zn coordinates to the salen pocket to give Zn-metalated salen (Zn-MS) complex. The other Zn ion acts as a node that connects to the Zn-MS metalloligands through the carboxylate groups to form coordination polymer (Zn-MSZn); when one equivalent Zn is used, the coordination polymer does not form. The resulting solution was heated at 120 8C for 60 min. During this time, formation of particles was observed. The reaction mixture was cooled to room temperature, and the precipitate was collected by centrifugation and washed several times with DMSO and methanol. The resulting particles were found to be stable in organic solvents (methanol, acetone, DMF, DMSO, and nonpolar solvents), water, and in the dried state. The morphology was characterized by field-emission scanning electron microscopy (SEM; Figure 1). The images show cubic particles with an average size of (308 36) nm. Dynamic light scattering (DLS) measurements on a colloidal Scheme 1. Preparation of Zn-MS-Zn coordination polymers as nanowires and their subsequent transformation into nanocubes.

Pyridine substituted N-heterocyclic carbene ligands as supports for Au(I)-Ag(I) interactions: formation of a chiral coordination polymer.

Abstract: Reaction of 1,3-bis(2-pyridinylmethyl)-1H-imidazolium tetrafluoroborate, [H(pyCH2)2im]BF4, with silver oxide in dichloromethane readily yields [Ag((pyCH2)2im)2]BF4, 1·BF4 1·BF4 is converted to the analogous Au(I)-containing species, [Au((pyCH2)2im)2]BF4, 3, by a simple carbene transfer reaction in dichloromethane Further treatment with two equivalents of AgBF4 produces the trimetallic species [AuAg2((pyCH2)2im)2(NCCH3)2](BF4)3, 4, which contains two silver ions each coordinated to the pyridine moieties on one carbene ligand and to an acetonitrile molecule in a T-shaped fashion Monometallic [Ag((py)2im)2]BF4, 5, and [Au((py)2im)2]BF4, 6, are made analogously to 1·BF4 and 3 starting from 1,3-bis(2-pyridyl)-imidazol-2-ylidene tetrafluoroborate, [H(py)2im]BF4 Addition of excess AgBF4 to 6 yields the helical mixed-metal polymer, {[AuAg((py)2im)2(NCCH3)](BF4)2}n, 7 which contains an extended Au(I)−Ag(I) chain with short metal−metal separations of 28359(4) and 29042(4) A Colorless, monometallic [Hg((pyCH2