Toward New Organic/Inorganic Superlattices:  Keggin Polyoxometalates in Langmuir and Langmuir−Blodgett Films

Clemente‐León, Miguel; Agricole, B.; Mingotaud, Christophe; Gómez‐García, Carlos J.; Coronado, and Eugenio; Delhaès, P.

doi:10.1021/la960576v

Cited by 196 publications

(141 citation statements)

References 32 publications

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“…2). [14] The lamellar structure so obtained consists of monolayers of the polyoxoanions alternating with bilayers of the organic surfactant (centrosymmetric LB film, see Fig. 1), as deduced from infrared linear dichroism and X-ray diffraction experiments.…”

Section: Lb Films Incorporating Polyoxometalate Clustersmentioning

confidence: 95%

Hybrid Organic/Inorganic Langmuir-Blodgett Films. A Supramolecular Approach to Ultrathin Magnetic Films

Coronado¹,

Mingotaud²

1999

Adv. Mater.

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Section: Lb Films Incorporating Polyoxometalate Clustersmentioning

confidence: 95%

Hybrid Organic/Inorganic Langmuir-Blodgett Films. A Supramolecular Approach to Ultrathin Magnetic Films

Coronado¹,

Mingotaud²

1999

Adv. Mater.

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“…[8] Because of this fundamental limitation, we opted to examine the stability and functionality of a {Mo 154 } ring encapsulated by dimethyldioctadecylammonium (DODA) cations (Scheme 1), because the DODA cation, with a length of about 2.5 nm, introduces amphiphilic-like properties into the POM-cation hybrid, and POM-DODA hybrids have shown some interesting properties, for example, for formation of Langmuir-Blodgett films. [9,10] Further, we hypothesized that encapsulation by DODA will also help to increase the stability of the nanoscale wheel cluster. Not only will nanoscale molecular assembly of the hybrid material be controlled by electrostatic interactions between the {Mo 154 }-ring polyanion and DODA cations, hydrophobic interactions between the alkyl chains should contribute to stabilization of the hybrid material in the solid state.…”

mentioning

confidence: 99%

Adsorption and Catalytic Properties of the Inner Nanospace of a Gigantic Ring‐Shaped Polyoxometalate Cluster

et al. 2009

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Porous materials with structurally well-defined nanoscale cavities (e.g., carbon nanostructures, zeolites, mesoporous silica, and coordination compounds) [1][2][3] are of great interest because of their unique properties such as adsorption, separation, exchange, and catalysis, which are all associated with the presence of a functional nanospace. In this respect, polyoxometalate clusters, which are nanosized metal-oxide macroanions built from molecular precursors with a range of unique redox and acidic properties, are ideally suited for the development of functional nanospaces but have not yet been thus explored.[ [5f-j]) The diameter of the POM ring and inner void space are about 3.9 and 1.7 nm, respectively, while the height of ring is about 1.8 nm.[7] Despite the great potential of ringshaped POMs to form porous materials, POM clusters have been greatly under-utilized and -investigated, probably due to poor stability. [8] Because of this fundamental limitation, we opted to examine the stability and functionality of a {Mo 154 } ring encapsulated by dimethyldioctadecylammonium (DODA) cations (Scheme 1), because the DODA cation, with a length of about 2.5 nm, introduces amphiphilic-like properties into the POM-cation hybrid, and POM-DODA hybrids have shown some interesting properties, for example, for formation of Langmuir-Blodgett films.[9, 10] Further, we hypothesized that encapsulation by DODA will also help to increase the stability of the nanoscale wheel cluster. Not only will nanoscale molecular assembly of the hybrid material be controlled by electrostatic interactions between the {Mo 154 }-ring polyanion and DODA cations, hydrophobic interactions between the alkyl chains should contribute to stabilization of the hybrid material in the solid state. As reported previously, [9] the POM-DODA hybrid shows high stability in CHCl 3 solution, while the ring structure of 1 is not robust in aqueous solution and the solid state (see Figures S1-S4, Supporting Information).Here we report on the inner nanospace functionality of POM-DODA hybrid (DODA) 23 [Mo 154 O 462 H 5 ]·n H 2 O (2). [11] Initially, dynamic light scattering (DLS) experiments were conducted to confirm the presence of the {Mo 154 } ring of 2 in solution and showed that the particle diameter in a solution in THF is about (4.0 AE 0.6) nm, similar to the size of the {Mo 154 } ring ( Figure S5, Supporting Information). Hence, these data are consistent with the hypothesis that the {Mo 154 } ring is stabilized after reaction of 1 with DODA, whereby the DODA cations effectively encapsulate the outer part of the ring, as shown in Scheme 1. Thermogravimetric analysis of 2 shows a weight loss of 4.7 % in the temperature range from 298 to 440 K ( Figure S6, Supporting Information), which corresponds to about 95 H 2 O molecules. To confirm removal of all H 2 O molecules, the temperature dependence of the IR spectrum was measured. The OH stretching and OH bending bands at 3400 and 1620 cm À1 , respectively, are observed at Scheme 1. Protection of {Mo 154 } ring b...

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“…The latter were performed by employing the MM3 force field as implemented in the The LB experiments were carried out with a laboratory-made trough [23]. Surface pressure was measured with a Pt Wilhelmy plate.…”

Section: Methodsmentioning

confidence: 99%

Towards Organization of Molecular Machines at Interfaces: Langmuir Films and Langmuir–Blodgett Multilayers of an Acid–Base Switchable Rotaxane

et al. 2006

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The design and synthesis of nanoscale species capable of performing controllable mechanical movements, that is, molecular machines, [1][2][3] is a topic of growing interest. Appealing examples of chemical compounds that have movable component parts are suitably designed catenanes, rotaxanes, and pseudorotaxanes. [4] In the past few years, several prototypes of artificial molecular machines based on these types of interlocked systems have been synthesized and subsequently investigated in the solution phase. [1][2][3] However, it is reasonable that, before functional supramolecular assemblies can find applications as nanoscale machines, they have to be interfaced with the macroscopic world by ordering them in some way. The next generation of molecular machines will need to be organized at interfaces, [5] deposited on surfaces, [6] or immobilized into membranes [7] or porous materials [8] so that they can behave coherently and can be addressed on the nanometer scale. Indeed, the preparation of modified electrodes [9] represents one of the most promising ways to achieve this goal. Solid-state electronic devices containing functional rotaxanes and catenanes are also being developed.[10]In this context we investigated, for the first time, the organization of a non-amphiphilic tricationic switchable rotaxane and its dumbbell-shaped component into Langmuir films and Langmuir-Blodgett (LB) multilayers by using a cospreading strategy. The Langmuir films have been characterized by surface pressure-area (P-A) isotherms, and subsequently transferred onto indium tin oxide (ITO) or CaF 2 supports to form LB multilayers, which were then studied by infrared (IR) and UV-vis spectroscopy, and voltammetric techniques. We found that the LB films exhibit a reversible switching behavior when exposed cyclically to bases and acids, and therefore are capable of transducing a chemical input signal into an electrical output signal, although we could not relate such a switching behavior to ring shuttling. The structures of the rotaxane 1, its dumbbell-shaped and ring components 2, dibenzo[24]crown-8 (DB24C8), and the anchor lipid hydrogen dihexadecylphosphate (HDHP) are represented in Scheme 1.The rotaxane 1, whose dumbbell-shaped component 2 comprises [11] two different recognition sites-namely, a dialkylammonium center and a 4,4′-bipyridinium unit-and an anthracene unit as one of the stoppers, was selected for this study because of its capability to function [12,13] as an acid-base-controllable molecular shuttle (Scheme 2). In a CH 3 CN solution COMMUNICATIONS

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Toward New Organic/Inorganic Superlattices: Keggin Polyoxometalates in Langmuir and Langmuir−Blodgett Films

Cited by 196 publications

References 32 publications

Hybrid Organic/Inorganic Langmuir-Blodgett Films. A Supramolecular Approach to Ultrathin Magnetic Films

Hybrid Organic/Inorganic Langmuir-Blodgett Films. A Supramolecular Approach to Ultrathin Magnetic Films

Adsorption and Catalytic Properties of the Inner Nanospace of a Gigantic Ring‐Shaped Polyoxometalate Cluster

Towards Organization of Molecular Machines at Interfaces: Langmuir Films and Langmuir–Blodgett Multilayers of an Acid–Base Switchable Rotaxane

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