Control of electronic properties of triphenylene by substitution

Thiessen, Alexander; Wettach, Henning; Meerholz, Klaus; Neese, Frank; Höger, Sigurd; Hertel, Dirk

doi:10.1016/j.orgel.2011.10.005

Cited by 16 publications

(12 citation statements)

References 57 publications

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“…Molecular precursors 1 and 2 (Figure b) featuring iodide and bromide substituents respectively were prepared following literature procedures. , The Au(111) single crystal substrate was cleaned by cycles of sputtering and annealing. 1 and 2 were deposited onto the clean Au(111) surface from a homemade Knudsen cell evaporator held at 160 and 215 °C, respectively.…”

Section: Experimental Methodsmentioning

confidence: 99%

Iodine versus Bromine Functionalization for Bottom-Up Graphene Nanoribbon Growth: Role of Diffusion

et al. 2017

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Deterministic bottom-up approaches for synthesizing atomically well-defined graphene nanoribbons (GNRs) largely rely on the surface-catalyzed activation of selected labile bonds in a molecular precursor followed by step growth polymerization and cyclodehydrogenation. While the majority of successful GNR precursors rely on the homolytic cleavage of thermally labile CBr bonds, the introduction of weaker C-I bonds provides access to monomers that can be polymerized at significantly lower temperatures, thus helping to increase the flexibility of the GNR synthesis process. Scanning tunneling microscopy (STM) imaging of molecular precursors, activated intermediates, and polymers resulting from stepwise thermal annealing of both Br and I substituted precursors for chevron GNRs reveals that the polymerization of both precursors proceeds at similar temperatures on Au(111). This observation is consistent with diffusionlimited polymerization of the surface-stabilized radical intermediates that emerge from homolytic cleavage of either the C-Br or the C-I bonds.3

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Section: Experimental Methodsmentioning

confidence: 99%

Iodine versus Bromine Functionalization for Bottom-Up Graphene Nanoribbon Growth: Role of Diffusion

et al. 2017

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“…The synthesis of 1 has been reported elsewhere. , Precursor 2 was obtained through monoiodination of 9,10-phenanthrenequinone followed by bromination to yield 2-bromo-7-iodophenanthrene-9,10-dione in 13% yield. Knoevenagel condensation with 1,3-diphenyl acetone followed by a Diels–Alder reaction with 2-ethynyl-1,1′-binaphthalene ( 6 ) afforded 2 in 47% yield as an inseparable 1:1 mixture of regioisomers with respect to the position of the I/Br substituents at the C6/C11 position of the triphenylene core (Figure a).…”

Section: Hierarchical On-surface Synthesis Of Controlled Gnr Heteroju...mentioning

confidence: 99%

Hierarchical On-Surface Synthesis of Graphene Nanoribbon Heterojunctions

et al. 2018

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Bottom-up graphene nanoribbon (GNR) heterojunctions are nanoscale strips of graphene whose electronic structure abruptly changes across a covalently bonded interface. Their rational design offers opportunities for profound technological advancements enabled by their extraordinary structural and electronic properties. Thus far, the most critical aspect of their synthesis, the control over sequence and position of heterojunctions along the length of a ribbon, has been plagued by randomness in monomer sequences emerging from step-growth copolymerization of distinct monomers. All bottom-up GNR heterojunction structures created so far have exhibited random sequences of heterojunctions and, while useful for fundamental scientific studies, are difficult to incorporate into functional nanodevices as a result. In contrast, we describe a hierarchical fabrication strategy that allows the growth of bottom-up GNRs that preferentially exhibit a single heterojunction interface rather than a random statistical sequence of junctions along the ribbon. Such heterojunctions provide a viable platform that could be directly used in functional GNR-based device applications at the molecular scale. Our hierarchical GNR fabrication strategy is based on differences in the dissociation energies of C-Br and C-I bonds that allow control over the growth sequence of the block copolymers from which GNRs are formed and consequently yields a significantly higher proportion of single-junction GNR heterostructures. Scanning tunneling spectroscopy and density functional theory calculations confirm that hierarchically grown heterojunctions between chevron GNR (cGNR) and binaphthyl-cGNR segments exhibit straddling Type I band alignment in structures that are only one atomic layer thick and 3 nm in width.

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“…In particular, over the past few decades, polycyclic aromatic systems (PASs) have become the workhorse of organic electronics. 1,2 This is due to the molecular properties that characterize these systems: they are πconjugated, which allows for conductance, 1,3 yet are relatively stable, as compared to other conjugated systems, e.g., polyenes; 4 they tend to pack closely, 5,6 which is important for charge mobility; 7 and they can be relatively easily modified through substitution with functional groups or annulation, which allows for tuning their electronic properties, [8][9][10] as well as other attributes, e.g., solubility. 11,12 The ability to tune their electronic properties is one of the greatest advantages of PASs as organic electronics because, in order to perform in such a capacity, the molecule must meet certain requirements.…”

Section: Introductionmentioning

confidence: 99%

Predicting bond-currents in polybenzenoid hydrocarbons with an additivity scheme

Paenurk

Feusi

Gershoni‐Poranne

2021

The Journal of Chemical Physics

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We report on the construction and application of a new bond-current additivity scheme for polybenzenoid hydrocarbons. The method is based on identification of the smaller substructures contained in the system, up to tricyclic subunits. Thus, it enables the prediction of any cata-condensed unbranched polybenzenoid hydrocarbon, using a library consisting of only four building blocks. The predicted bond-currents can then be used to generate NICS values, the results of which validate previous observations of additivity with NICS-XY-Scans. The limitations of the method are probed, leading to clearly delineated and apparently constant error boundaries, which are independent of the molecular size. It is shown that there is a relationship between the accuracy of the predictions and the molecular structure and specific motifs that are especially challenging are identified. The results of the additivity method, combined with the transparent description of its strengths and weaknesses, ensure that this method can be used with well-defined reliability for characterization of polybenzenoid hydrocarbons. The resource-efficient and rapid nature of the method make it a promising tool for screening and molecular design.

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Control of electronic properties of triphenylene by substitution

Cited by 16 publications

References 57 publications

Iodine versus Bromine Functionalization for Bottom-Up Graphene Nanoribbon Growth: Role of Diffusion

Iodine versus Bromine Functionalization for Bottom-Up Graphene Nanoribbon Growth: Role of Diffusion

Hierarchical On-Surface Synthesis of Graphene Nanoribbon Heterojunctions

Predicting bond-currents in polybenzenoid hydrocarbons with an additivity scheme

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