Supramolecular Assemblies Comprised of One-Dimensional Mixed Valence Platinum Complex and Anionic Amphiphiles in Organic Media

Kimizuka, Nobuo; Oda, N.; Kunitake, Toyoki

doi:10.1246/cl.1998.695

Cited by 40 publications

(29 citation statements)

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“…The spectral shift observed for reassembled [Pt(en) 2 ][PtCl 2 (en) 2 ] complex reflects changes in the LUMO-HOMO band gap, i.e., 1D electronic structure of chloro-bridged mixed valence chains. It is sensitive to molecular structure of anionic lipids and their molecular organization [3,4,7].…”

Section: Resultsmentioning

confidence: 99%

“…However, covalent polymers are devoid of reversible polymerization/de-polymerization properties, and hence they do not provide conjugated electronic structures which are formed in response to selfassembly. To develop self-assembling molecular wires, we devised supramolecular strategies to disperse linear metal complexes as nanowires in organic media [3][4][5][6][7][8][9][10][11][12][13]. Quasi-1D, halogen-bridged metal complexes [M(en) 2 ][M 0 X 2 (en) 2 ] (ClO 4 ) 4 (M, M 0 ; Pt, Pd, Ni, X; Cl, Br, I, en; 1,2-diaminoethane) are attracting much interest due to their d-p conjugated electronic structures with charge density wave state [14] and large nonlinear optical susceptibilities [15].…”

Section: Introductionmentioning

confidence: 99%

“…4 complexes display aggregate morphology and charge transfer (CT, Pt II -Pt IV ) absorption characteristics which vary depending on metal ions [5,7], bridging halogen ions [8], solvents [9] and lipid chemical structures [3,4,7]. Some of the complexes display supramolecular thermochromism, as a result of reversible dissociation and reassembly of coordination chains in solution [4][5][6][7][8][9][10][11] and self-assembly of molecular wires in organic media, giving a new research field of neuromorphic nanomaterials.…”

Section: Introductionmentioning

confidence: 99%

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Supramolecular solvatochromism. Effect of solvents on the self-assembly and charge transfer absorption characteristics of lipid-packaged, linear mixed-valence platinum complexes

Kuroiwa

Oda

Kimizuka

2006

Science and Technology of Advanced Materials

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Lipid-packaged, mixed-valence linear platinum complexes are dispersed in chloroform, chlorocyclohexane and in methylcyclohexane. They show indigo-colors, which are identical to solid samples. These lipid-complexes display supramolecular thermochromism, resulting from heat-induced dissociation and recovery of coordination chains. Unexpectedly, reassembled samples show altered CT absorption spectra. In chloroform, the reassembled complex gives indigo-color, while the chlorocyclohexane and methylcyclohexane dispersions show blue and red-colors, respectively. These color changes indicate enhanced solvation of lipid-packaged platinum complexes after the heat treatment. The thermal re-assembly also affects the aggregate morphology, and leads to the formation of nanowires, nanofibers and nanoparticles depending on the solvents employed. The conversion of pseudo one-dimensional (1D) inorganic complexes to lipophilic supramolecular assemblies thus gives solvatochromic properties, which are elements not existing in the conventional solid-state inorganic chemistry.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Supramolecular solvatochromism. Effect of solvents on the self-assembly and charge transfer absorption characteristics of lipid-packaged, linear mixed-valence platinum complexes

Kuroiwa

Oda

Kimizuka

2006

Science and Technology of Advanced Materials

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“…[9,10] The introduction of lipid counteranions to cationic mixed-valence compounds can lead to the dispersion of nanowires in organic media, resulting in the emergence of functionality not available in the solid state. [9][10][11] In this study, we first focus on the self-assembly of discrete mixed-valence complexes with lipid amphiphiles. It is wellknown that the lipid amphiphiles make it possible to aggregate and self-assemble functional coordination polymers.…”

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confidence: 99%

Self‐Assembly of Tubular Microstructures from Mixed‐Valence Metal Complexes and Their Reversible Transformation by External Stimuli

et al. 2011

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Controlled self-assembly of metal complexes is of high scientific and technological importance for the development of multi-functional materials and devices. Among various types of metal complexes, mixed-valence complexes have attracted much attention because of their wide range of interesting physical and chemical properties from chargetransfer interactions between metal ions linked via bridging ligands. [1][2][3] In particular, low-dimensional assembly of such mixed-valence complexes gives rise to specific electronic, [4a] magnetic, [4b,c] and optical properties.[4d] Moreover, the assembly of discrete binuclear mixed-valence complexes has been suggested as a basis for forming molecular communication system such as quantum cellular automata.[5] Ideally, the characteristics of such systems would be tunable by controlling the spatial arrangement of the mixed-valence complexes, resulting in electric interaction among metal complexes without covalent or coordinative linkage.In this context, supramolecular strategies have been developed to construct nanoassemblies of coordination compounds, such as one-dimensional (1D), [6] two-dimensional (2D), [7] and three-dimensional (3D) metal complexes. [8] However, studies to date have focused on the conversion of crystalline coordination polymers to nanowires, nanosheets, and nanoparticles, which can be regarded as isolation of lowdimensional structures from 3D solids (Scheme 1a). In contrast, there exist no reports on the reversible and hierarchical self-assembly of discrete mixed-valence metal complexes (which could not interact with each other) into 1D nanowires, 2D nanosheets, or 3D nanoarchitectures, a concept which would lie at the very heart of bottom-up nanotechnology (Scheme 1 b). However, we have developed selfassembled nanowires by amphiphilically modifying such Scheme 1. Schematic illustrations of the a) isolation and b) integration approaches for constructing nanoassemblies of coordination compounds. c) Chemical structures of lipids and ruthenium complexes.

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“…Indeed, in halogen-bridged mixed-valence platinum-chain compounds, molecules with long alkyl chains, such as alkyl sulfosuccinates, have been used as lipophilic counter ions, which enable these compounds to be dispersed in organic solvents without disrupting their chain structures. [11] The compound [Ni(L) 2 Br]Br 2 (L: 1,2-diaminohexadecane), in which a long alkyl chain (C 14 H 29 ) is introduced in the ligand molecule L, has been synthesized for the first time in the present study. Each ligand molecule has two amino groups as well as a long alkyl chain.…”

mentioning

confidence: 99%

Ultrafast Optical Switching by using Nanocrystals of a Halogen‐Bridged Nickel‐Chain Compound Dispersed in an Optical Polymer

et al. 2007

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As the development of optical communication networks progresses, the demand for ultrafast optical switching with terahertz operation is rising. Nonlinear optical (NLO) materials with large third-order nonlinear susceptibility v (3) [1] and a small relaxation time t 1 of the photoexcited states are indispensable to these devices. Recently, it has been reported that 1D Mott insulators of halogen-bridged Ni-chain compounds exhibit large v (3) [2] and small t 1 . [3] For the application of these Ni compounds to ultrafast optical switching devices using, for example, optical waveguides, fabrication of a thin film is a most important issue. Here, we report a method for the fabrication of high-quality thin films, in which nanocrystals of a Ni compound with alkyl chains are dispersed in an optical polymer, PMMA (poly(methyl methacrylate)). In these films, terahertz repetition of optical switching by two-photon absorption (TPA) processes is demonstrated. The present approach represents a new strategy for the application of transitionmetal compounds to optical switching devices. Figure 1a shows the crystal structure of [Ni(chxn) 2 Br]Br 2 (chxn=cyclohexanediamine), [4] which is representative of the halogen-bridged Ni-chain compounds. In this compound, the Ni 3+ and Br -ions are arranged alternately along the b-axis.Four N atoms of the amino groups in two chxn molecules coordinate a Ni 3+ ion in a plane normal to b and produce a strong ligand field, so that the Ni 3+ ion is in a low-spin state and an unpaired electron exists in the d z 2 orbital. The d z 2 orbitals of Ni 3+ and the p z orbitals of Br -form a purely 1D electronic state. Due to the large electron-electron Coulomb repulsion (U) on the Ni site, a Mott-Hubbard gap is opened in the Ni 3d-band. As shown in Figure 1f, the occupied Br p-band is located between the Ni 3d upper-Hubbard (UH) band and the lower-Hubbard (LH) band, so that the chargetransfer (CT) transition from Br to Ni corresponds to the optical gap.[5]Previous electroreflectance (ER) and third-harmonic generation (THG) spectroscopic studies have revealed that [Ni(chxn) 2 Br]Br 2 shows the largest v (3) among 1D semiconductors; the maximum values of Imv(-x;0,0,x) and v (3) (-3 x;x,x,x) were 9 × 10 -5 esu (1 esu = 3.335641 × 10 -10 C) and 4 × 10 -8 esu, respectively. [2,6,7] These measurements were performed on single crystals (Fig. 1c) because the fabrication of film samples has not been successful, owing to the low solubility in organic solvents as well as the difficulty of vapor deposition. One way of fabricating an optical thin film in such cases is to disperse nanocrystals in optically transparent polymers. This method has been employed for the fabrication of good optical films of single-wall carbon nanotubes, using gelatin, polyvinyl alcohol, and carboxymethylcellulose as matrices.[8-10] Before we can apply this method to a Ni compound, its affinity to organic solvents should be improved. An effective method for this is to introduce alkyl chains. Indeed, in halogen-bridged mixed-valence plati...

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Supramolecular Assemblies Comprised of One-Dimensional Mixed Valence Platinum Complex and Anionic Amphiphiles in Organic Media

Cited by 40 publications

References 10 publications

Supramolecular solvatochromism. Effect of solvents on the self-assembly and charge transfer absorption characteristics of lipid-packaged, linear mixed-valence platinum complexes

Supramolecular solvatochromism. Effect of solvents on the self-assembly and charge transfer absorption characteristics of lipid-packaged, linear mixed-valence platinum complexes

Self‐Assembly of Tubular Microstructures from Mixed‐Valence Metal Complexes and Their Reversible Transformation by External Stimuli

Ultrafast Optical Switching by using Nanocrystals of a Halogen‐Bridged Nickel‐Chain Compound Dispersed in an Optical Polymer

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