Low-symmetry distortions in Extended Metal Atom Chains (EMACs): Origins and consequences for electron transport

Georgiev, Vihar P.; Mohan, P. J.; DeBrincat, Daniel; McGrady, John E.

doi:10.1016/j.ccr.2012.05.025

Cited by 73 publications

(45 citation statements)

References 90 publications

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“…45,[50][51][52][53] However, as discussed by McGrady in the context of pseudo-1D metal string complexes, efficient through-molecule conductance can be achieved through frontier orbitals which are distributed near, and energetically aligned with, the electrodes and need not be evenly distributed along the entire molecular backbone. 54,55 Recently, the molecular conductances of Pt(II) complexes trans- Through numerous studies of molecular junctions, the nature of the molecule-electrode contact has proven important, 57 and recognition of the role that anchor groups play in the electrical performance of the junction has led to the development of a wide range of contacting groups and electrode materials. [58][59][60][61][62][63] However, even well-known contacting groups such as thiolates bind to a range of surface sites, including terraces or near to adatoms as well as idealised pristine atomically flat terraces, giving rise to a range of molecular conductance signatures from a given molecular backbone.…”

Section: Introductionmentioning

confidence: 99%

Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions

et al. 2017

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and break-off distance data, we demonstrate that a PPh 3 supporting ligand in the platinum complexes can provide an alternative contact point for the STM tip in the molecular junctions, orthogonal to the terminal CuCSiMe 3 group. The attachment of hexyloxy side chains to the diethynylbenzene ligands, e.g. trans-Pt{CuCC 6 H 2 (Ohex) 2 CuCSiMe 3 } 2 (PPh 3 ) 2 (Ohex = OC 6 H 13 ), hinders contact of the STM tip to the PPh 3 groups and effectively insulates the molecule, allowing the conductance through the full length of the backbone to be reliably measured. The use of trialkylphosphine (PEt 3 ), rather than triarylphosphine (PPh 3 ), ancillary ligands at platinum also eliminates these orthogonal contacts. These results have significant implications for the future design of organometallic complexes for studies in molecular junctions.

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Section: Introductionmentioning

confidence: 99%

Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions

et al. 2017

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“…To examine Pd-Pd bonding nature, gas phase theoretical optimizations with DFT methods (B3LYP/LANL2DZ) [20] were performed on the model compounds [Pd 8 (M3), which correspond to the real structures of 1, 2, and 3, respectively, though the phenyl groups of the dpmppm ligands were replaced with H atoms (Figures S14-S15 and Table S8). The optimized structures are basically in agreement with the crystal structures besides systematic increases of the Pd-Pd distances.…”

Section: Methodsmentioning

confidence: 99%

“…Several groups have synthesized molecular EMACs by using linearly well-designed multidonor organic ligands as guiding templates, [3][4][5][6][7][8][9][10][11][12][13][14] establishing Ni 9 and Ni 11 chains supported by polypyridyl-and polynaphthyridylamide ligands, respectively, as the longest end of structurally characterized examples. [9,10] These compounds are promising building blocks for extending the metal atom chains, whereas the length of the molecular EMACs is still quite limited and entirely depends on the length of the organic ligands.…”

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confidence: 99%

Self‐Alignment of Low‐Valent Octanuclear Palladium Atoms

Nakamae¹,

Takemura²,

Kure³

et al. 2014

Angewandte Chemie

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A linear tetraphosphine, meso-bis [(diphenylphosphinomethyl)phenylphosphino]methane (dpmppm) was used to synthesize linear octapalladium-extended metal atom chains as discrete molecules of 4 ](BF 4 ) 4 (1) and 4 L 2 ](BF 4 ) 4 (L = 2,6-xylyl isocyanide (XylNC; 2), acetonitrile (3), and N,N-dimethylformamide (dmf; 4)), which are stable in the solution states and show interesting temperature-dependent photochemical properties in the near IR region. Variable temperature NMR studies demonstrated that at higher temperature T % 140 8C the Pd 8 chains were dissociated into Pd 4 fragments, which were thermodynamically self-aligned to restore the Pd 8 chains at lower temperature T < 60 8C. The coldspray ionization mass spectra suggested a possibility for further aggregation of the linear tetrapalladium units.Metallic materials have widely been utilized in a variety of electronic devices, and their downsizing into nanoscaled fabricates is extremely desired in modern industries from the viewpoint of saving energy and resources to establish sustainable future systems. [1] Among the motifs of nanostructures, one-dimensional arrays of metal atoms (meso-to nanowires) have attracted rapidly growing attention as nanoscaled multifunctional devices. This has been promoted by the synthetic developments, e.g., the electrodeposition of metal atoms on step-edges of crystalline substrates into nanochannels and between nanogaps as well as physical manipulations with scanning probe microscopy, electron-beam lithography, and break junction techniques. [2] Along this line, the ultimately thinnest electric wire that may consist of a single-metal-atom chain sheathed with insulating materials, so-called "extended metal atom chains" (EMACs), is one of the most theoretically important and challenging targets, because the anisotropically confined electrons in a single metallic chain would be predicted to exhibit fundamentally different transport properties, conceptually corresponding to the transition from atomic to bulk electronic behavior.Although their reproducible synthesis is extremely difficult at present, one of the promising strategies involves a procedure of molecular chemistry that constructs linearly ordered multinuclear metal complexes as discrete molecular EMACs. Several groups have synthesized molecular EMACs by using linearly well-designed multidonor organic ligands as guiding templates, [3][4][5][6][7][8][9][10][11][12][13][14] establishing Ni 9 and Ni 11 chains supported by polypyridyl-and polynaphthyridylamide ligands, respectively, as the longest end of structurally characterized examples. [9,10] These compounds are promising building blocks for extending the metal atom chains, whereas the length of the molecular EMACs is still quite limited and entirely depends on the length of the organic ligands. We have studied linearly ordered metal complexes supported by a triphosphine, bis(diphenylphosphinomethyl)phenylphosphine (dpmp), and reported that linear Pt 2 M trinuclear complexes, [Pt 2 M(m-dpmp) 2 L 2 ] 2+ (M = Pt, Pd, L = ...

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“…In particular,aseries of linear transition metal complexes based on oligopyridylamide ligandsh ave established the so-called extended metal atom chains (EMACs), which are highly attractive since they potentially serve as conducting wires in molecular microelectronics. [2] The world record of the longest linear arrangemento ft ransition metal ions in ad iscrete molecule is currently held by such ac hain complex with eleven mixed-valent Ni II/III centers. [3] Although as eries of these chain-like transition metal complexes (homo-polynuclear:C r, Co, Ni, Ru, Rh;h etero-polynuclear also Mn, Fe, Zn, Mo, W, Pd, Pt) has been explored, [2a,c,d] significantly less attention has been devoted to EMAC-type and related copper arrays in both Cu oxidation states + 1a nd + 2.…”

Section: Introductionmentioning

confidence: 99%

Linear Copper Complex Arrays as Versatile Molecular Strings: Syntheses, Structures, Luminescence, and Magnetism

Stollenz

2019

Chemistry A European J

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The defined linear arrangement of metal atoms in discrete coordination complexes or polymers is still one of the most intriguing challenges in synthetic chemistry. These chain arrangements are of fundamental importance, because of their potential applications as molecular wires and single molecule magnets (SMM) in microelectronic devices on a molecular scale. Oligonuclear Group 11 metal complexes with suitable bridging ligands, specifically those that are based on copper as the first choice of a cheap precursor coinage metal, are of particular interest in this regard. This is due to the superior luminescence properties of these linear clusters that often show d10⋅⋅⋅d10 interactions in their molecular structures. The combination of CuI with heavier coinage metal ions results in tunable emissive arrays that are also stimuli‐responsive. Thus, both linear multinuclear CuI and linear heteropolymetallic CuI/AgI as well as CuI/AuI clusters are excellent candidates for applications in molecular/organic light‐emitting devices (OLEDs). Alternatively, paramagnetic multinuclear cupric arrays are prominent as potential molecular wires with enhanced magnetic properties through multiple coupled d9 centers. This Review covers the whole range of linear multinuclear assemblies of cuprous and cupric ions in complexes and coordination polymers, their syntheses, photophysical behavior, and magnetic properties. Moreover, recent advances in the rapidly progressing field of hetero‐CuI/AgI and CuI/AuI molecular strings are also discussed.

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Low-symmetry distortions in Extended Metal Atom Chains (EMACs): Origins and consequences for electron transport

Cited by 73 publications

References 90 publications

Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions

Insulated molecular wires: inhibiting orthogonal contacts in metal complex based molecular junctions

Self‐Alignment of Low‐Valent Octanuclear Palladium Atoms

Linear Copper Complex Arrays as Versatile Molecular Strings: Syntheses, Structures, Luminescence, and Magnetism

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