On‐Surface Reactions

Lindner, Robert; Kühnle, Angelika

doi:10.1002/cphc.201500161

Cited by 127 publications

(131 citation statements)

References 109 publications

(97 reference statements)

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“…[7,8] These surface-stabilized species can lead to compounds that are difficult or impossible to obtain via conventional synthetic procedures. [9][10][11][12] Herein, we combine both of the aforementioned features.…”

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confidence: 99%

On‐Surface Bottom‐Up Synthesis of Azine Derivatives Displaying Strong Acceptor Behavior

et al. 2018

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On-surface synthesis is an emerging approach to obtain, in asingle step,precisely defined chemical species that cannot be obtained by other synthetic routes.The control of the electronic structure of organic/metal interfaces is crucial for defining the performance of many optoelectronic devices.A facile on-surface chemistry route has now been used to synthesize the strong electron-acceptor organic molecule quinoneazine directly on aC u(110) surface,v ia thermally activated covalent coupling of para-aminophenol precursors. The mechanism is described using ac ombination of in situ surface characterization techniques and theoretical methods. Owing to astrong surface-molecule interaction, the quinoneazine molecule accommodates 1.2 electrons at its carbonyl ends, inducing an intramolecular charge redistribution and leading to partial conjugation of the rings,conferring azo-character at the nitrogen sites.Organicheterostructuresbasedonelectronacceptor-donor organic molecules on surfaces have become strategic materials owing to their huge technological impact in fields such as organic light-emitting diodes (OLEDs), organic field effect transistors (OFETs), or solar cell devices,amongst others.In electronic devices,o rganic layers are placed on metallic surfaces for electrical contact, and the structure of the metalorganic interface enormously affects the performance.[1] In particular,s ome molecules promote charge transfer at the interface with metal electrodes owing to their donor (acceptor) nature,which may induce energy level realignment that can be exploited to tune the transport properties of the system. [1][2][3][4][5] Despite the potential impact of this approach, only af ew molecules have been shown to efficiently donate (or accept) significant charge,t his quality being related to the presence of donor (acceptor) moieties in their structures.[6] A typical example is tetracyano-p-quinodimethane (TCNQ), as trong acceptor molecule that when deposited on Cu(100) accommodates around 1.6 electrons whereby almost one electron aromatizes the central hexagonal ring and the remaining fraction of the charge is accommodated in one of the peripheral nitrogen atoms of the cyano groups.[3]On the other hand, on-surface synthesis can generate unique molecules or extended molecular architectures that have been rationally formed via alternative synthetic routes to those available through solution-based chemistry. [7,8] These surface-stabilized species can lead to compounds that are difficult or impossible to obtain via conventional synthetic procedures. [9][10][11][12] Herein, we combine both of the aforementioned features. We show that the on-surface coupling reaction of two simple and inexpensive para-aminophenol (p-Ap) molecules can be employed to form aq uinonoid-like derivative,q uinoneazine (QAz). This molecule has been theoretically proposed for organic electrodes owing to their extreme redox voltages,and it can also be employed as an intermediate in the preparation of several chemically and biologically active ...

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On‐Surface Bottom‐Up Synthesis of Azine Derivatives Displaying Strong Acceptor Behavior

et al. 2018

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“…19). Therefore, it is of interest to determine whether dehydrogenation and homocoupling also take place in the case of FePc on Cu(111), at what temperatures these changes occur, and to understand the physics of the involved surface and reaction processes.…”

Section: Introductionmentioning

confidence: 99%

Iron phthalocyanine on Cu(111): Coverage-dependent assembly and symmetry breaking, temperature-induced homocoupling, and modification of the adsorbate-surface interaction by annealing

Snezhkova

Bischoff

et al. 2016

The Journal of Chemical Physics

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We have examined the geometric and electronic structures of iron phthalocyanine assemblies on a Cu(111) surface at different sub- to mono-layer coverages and the changes induced by thermal annealing at temperatures between 250 and 320 °C by scanning tunneling microscopy, x-ray photoelectron spectroscopy, and x-ray absorption spectroscopy. The symmetry breaking observed in scanning tunneling microscopy images is found to be coverage dependent and to persist upon annealing. Further, we find that annealing to temperatures between 300 and 320 °C leads to both desorption of iron phthalocyanine molecules from the surface and their agglomeration. We see clear evidence of temperature-induced homocoupling reactions of the iron phthalocyanine molecules following dehydrogenation of their isoindole rings, similar to what has been observed for related tetrapyrroles on transition metal surfaces. Finally, spectroscopy indicates a modified substrate-adsorbate interaction upon annealing with a shortened bond distance. This finding could potentially explain a changed reactivity of Cu-supported iron phthalocyanine in comparison to that of the pristine compound.

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“…In principle, many other components can be ‘wired’ up using analogous methods, through application of any number of different reactions, even exploiting recent advances in ‘on-surface’ synthesis, 71 to potentially create circuits with broader functionality. By modifying the conditions used to effect surface-based reactions, we demonstrate further the impact of intermolecular steric effects on in situ synthesized product yields, a factor not typically important to consider when conducting reactions in solution.…”

Section: Resultsmentioning

confidence: 99%