Organometallic molecular wires as versatile modules for energy-level alignment of the metal–molecule–metal junction

Self Cite

What new scientific questions does this concept article raise? This concept article summarizes recent developments of the single-molecule conductance study.W hile many findings have been highlighted, al ot of scientific issues remain to be solved, for example, roles of metal ions for high-conductance, effects of the supporting ligands on metal centers, and impact of metal-metal interactions on conducting properties. Moreover,exploration of uncovered properties of inorganic and organometallic molecular wires is another important topic. What prompted you to investigate this field? The field of molecular wires is attractive for synthetic chemists not only because their properties can be finely tuned by modulation of the molecular structures, but because the field is the playground of many scientists across different disciplines involving chemists, physicists and theoreticians. Discussions with scientists of different fields are stimulating and give us ideas for the new design of molecular wires. What other topics are you working on at the moment? Besides the single-molecule conductance study of organometallic molecular wires, we are interested in electron-transfer and charge-delocalization behaviors of organometallic mixed-valence complexes. Recently we found at wo-dimensional highly charge-delo-calized system over an anometer dimension (see Chem. Eur.J. 2017, 23,2 067), which would be useful for molecule-based nano-devices. Invited for the cover of this issue is the group of Y. Tanaka and M. Akita at the Tokyo Institute of Technology.T he image depicts the jigsaw puzzle of inorganic and organometallic molecularw ires, in which their functionality can be easily tuned by changing their transition metal centers.Read the full text of the article at

Section: Organometallic Metal–acetylide Systems For Highly Conductingmentioning

confidence: 96%

Inorganic and Organometallic Molecular Wires for Single‐Molecule Devices

Tanaka

Kiguchi

Akita

2017

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“…This yieldedavalue of E F ÀE takes place through non-resonant tunneling. [42][43][44] Ta ble 1 shows ac omparison between experimental and theoretical conductances, along with other relevant junction parameters.…”

Section: Resultsmentioning

confidence: 98%

“…Ak ey factor governing the conductance of am olecular junctioni st he position of the Fermi level of am etal electrode withr espect to the molecular HOMO and LUMO levels.I nt urn, this energy alignment is sensitive to the chemical nature of the contacting groups,w hich bind the molecule to the electrode, and also the precise configuration of the metal electrode-molecule contact. [37][38][39][40][41][42] To determine E F ,t he predicted conductance values of all molecules were compared with the experimental values and as ingle common value of E F was chosen, which gave the closesto verall agreement. This yieldedavalue of E F ÀE takes place through non-resonant tunneling.…”

Section: Resultsmentioning

confidence: 99%

Constructive Quantum Interference in Single‐Molecule Benzodichalcogenophene Junctions

Baghernejad

Yang

Al‐Owaedi

et al. 2020

Heteroatom substitution into the cores of alternant, aromatich ydrocarbons containing only even-membered rings is attracting increasing interesta samethod of tuning their electrical conductance.H ere, the effect of heteroatom substitution into molecular cores of non-alternant hydrocarbons, containing odd-membered rings,i se xamined. Benzodichalcogenophene (BDC) compounds are rigid, planar p-conjugated structures,w ith molecular cores containing five-membered rings fused to as ix-membered aryl ring. To probe the sensitivity or resilience of constructive quantumi nterference (CQI) in these non-bipartite molecular cores,t wo C 2 -symmetric molecules (I and II) and one asymmetric molecule (III) were investigated. I( II) contains S( O) heteroatoms in each of the five-membered rings, while III containsa nSin one five-membered ring anda nOin the other.D ifferences in their conductances arise primarily from the longerS ÀCa nd shorterO ÀCb ond lengths compared with the CÀCbond and the associatedc hangesint heir resonancei ntegrals. Although the conductanceo fI II is significantlyl ower than the conductances of the others, CQI was found to be resilientand persist in all molecules.[a] Dr.

“…In seeking to enhance the wire‐like response, significant attention was turned to ruthenium bis(alkynyl) complexes, which are generally thought to offer more significant d–π orbital mixing in the occupied frontier molecular orbitals . The thioacetate complex trans ‐[Ru(C≡CC 6 H 4 SAc‐4) 2 (dppm) 2 ] (dppm=1,1‐bis(diphenylphosphino)methane) has been assembled into monolayers and studied within a scanning tunnelling microscope break junction (STM‐BJ), with a comparison made to the oligo(phenyleneethynylene) (OPE) compound 1,4‐(4‐AcSC 6 H 4 C≡C) 2 C 6 H 4 as a benchmark.…”

Section: Introductionmentioning

confidence: 99%

“…The higher conductance has been attributed to both the shorter molecular length and the extensive Ru(d)−C≡C(π) mixing in the metal complex . These concepts have been extended to other examples of organometallic wires based on group 8 metal centres and the trans ‐bis(alkynyl) motif, with topics of interest including the exploration of surface contacting groups, the inclusion of multiple metal centres along the molecular back‐bone and electronic function beyond that of a simple wire, such as charge storage and gated transistor‐like response …”

Section: Introductionmentioning

confidence: 99%

Single‐Molecule Conductance Studies of Organometallic Complexes Bearing 3‐Thienyl Contacting Groups

Bock

Al‐Owaedi

Eaves

et al. 2017

The compounds and complexes 1,4‐C6H4(C≡C‐cyclo‐3‐C4H3S)2 (2), trans‐[Pt(C≡C‐cyclo‐3‐C4H3S)2(PEt3)2] (3), trans‐[Ru(C≡C‐cyclo‐3‐C4H3S)2(dppe)2] (4; dppe=1,2‐bis(diphenylphosphino)ethane) and trans‐[Ru(C≡C‐cyclo‐3‐C4H3S)2{P(OEt)3}4] (5) featuring the 3‐thienyl moiety as a surface contacting group for gold electrodes have been prepared, crystallographically characterised in the case of 3–5 and studied in metal|molecule|metal junctions by using both scanning tunnelling microscope break‐junction (STM‐BJ) and STM‐I(s) methods (measuring the tunnelling current (I) as a function of distance (s)). The compounds exhibit similar conductance profiles, with a low conductance feature being more readily identified by STM‐I(s) methods, and a higher feature by the STM‐BJ method. The lower conductance feature was further characterised by analysis using an unsupervised, automated multi‐parameter vector classification (MPVC) of the conductance traces. The combination of similarly structured HOMOs and non‐resonant tunnelling mechanism accounts for the remarkably similar conductance values across the chemically distinct members of the family 2–5.