Vibrational modes and changing molecular conformation of perfluororubrene in thin films and solution

Anger, F.; Scholz, Reinhard; Gerlach, Alexander; Schreiber, Frank

doi:10.1063/1.4922052

Cited by 5 publications

(8 citation statements)

References 57 publications

(81 reference statements)

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“…The observed equal absorption signals at all angles for the F 14 -RUB and PF-RUB films indicate that the molecules do not exhibit a distinct orientation but are disordered or polycrystalline within the film. This is in good agreement with previous results from PF-RUB and F 14 -RUB thin films. , …”

Section: Resultssupporting

confidence: 93%

“…Similarly to RUB, thin films of fluorinated rubrene have been shown to grow disordered on silicon, , which allows oxygen to penetrate all films. Thus, a stabilizing mechanism due to molecular ordering as it occurs particularly in the bulk of RUB single crystals, where it leads to a reduction of the susceptibility to oxidation due to sterical hindrance, can be neglected.…”

Section: Resultsmentioning

confidence: 99%

“…In order to verify these considerations and gain further insights into the actual nature of the signature of the PF-RUB NEXAFS resonances, we performed DFT-computations using the StoBe package, which allows the reliable simulation of polycyclic aromatic hydrocarbons and their derivatives . Since in mature PF-RUB thin films molecules with both planar and twisted tetracene backbones may occur, isomers in both D 2 (twisted) and C 2 h (planar) symmetry , were considered for the computations. As these results show that the computed spectra of the different species are virtually identical (for details see the Supporting Information), we do not distinguish between the different conformations in the following.…”

Section: Resultsmentioning

confidence: 99%

“…This is in good agreement with previous results from PF-RUB and F 14 -RUB thin films. 24,38 In general, in the absence of a distinct dichroism it cannot directly be discriminated between statistically oriented molecules and molecules with a uniform orientation of 55°, 45 which represents the so-called magic angle where the dichroism disappears. 44 However, since the tetracene backbone and the phenyl side groups exhibit relative twists between each other and both of them yield resonances with different transition dipole moment (TDM) orientation, this allows their individual orientation analysis.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Enhanced Stability of Rubrene against Oxidation by Partial and Complete Fluorination

et al. 2016

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We report on the oxidation potential of partially fluorinated (C42F14H14, F14-RUB) and perfluorinated rubrene (C42F28, PF-RUB) studied by cyclic voltammetry (CV) in solution as well as by spectroscopic ellipsometry and near edge X-ray absorption fine structure (NEXAFS) spectroscopy in thin films in combination with density functional theory computations. Due to their different electronic structure, the fluorinated derivatives have a higher oxidation potential and are more stable than rubrene (C42H28, RUB).

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Enhanced Stability of Rubrene against Oxidation by Partial and Complete Fluorination

et al. 2016

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“…It was proposed that this conformational mismatch is the reason why growth of epitaxial rubrene on top of an adsorbed rubrene monolayer is not possible, thus explaining why only polycrystalline thin films are obtained on most surfaces . Optical measurements of hydrogenated rubrene and both fully and partially fluorinated rubrene thin films on SiO 2 suggest a predominance of the twisted conformation. − Scanning tunneling microscopy (STM) studies of rubrene adsorption hint at similar conclusions, although most studies were performed at low temperature and could result in significantly different outcomes. − …”

Section: Introductionmentioning

confidence: 98%

Rubrene Versus Fluorine-Functionalized Rubrene Molecules on a Metal Surface: Self-Assembly, Electronic Structure, and Energy Alignment of a Monolayer on Ag(100)

et al. 2019

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The geometric and electronic structures of a monolayer of rubrene and of a fluorinated rubrene derivative (FM-rubrene), adsorbed on a Ag(100) surface, were determined using scanning tunneling microscopy (STM), ultraviolet photoemission spectroscopy (UPS), and inverse photoemission spectroscopy (IPS) to study the influence of fluorinefunctionalization on self-assembly, molecular energy levels, and energy-level alignment. STM images at room temperature reveal that the molecules form different molecular assemblies at the monolayer coverage and have the tetracene backbones nearly parallel to the surface, with strongly splayed phenyls. While the assemblies are highly ordered, the molecular orientation and intermolecular spacings differ from those of the respective molecular crystals and thus do not act as templates for the epitaxial growth of ordered multilayer molecular films. UPS and IPS measurements indicate that the frontier orbitals of an adsorbed FM-rubrene molecular layer are shifted downward with respect to the Ag(100) Fermi level by 0.2 eV as compared to those of a rubrene monolayer. Moreover, the intrinsic molecular dipole of FM-rubrene contained in the first layer leads to an interface dipole of 0.2 eV, further shifting added molecular layers to higher energies. Comparison of the adsorption of rubrene to that of FM-rubrene on Ag(100) provides valuable insights into the nature of the molecule surface and intermolecular interactions that drive self-assembly and energy-level alignment, as well as their effects on the potential growth of ordered molecular multilayers.

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Perfluorinated and Half-Fluorinated Rubrenes: Synthesis and Crystal Packing Arrangements

Sakamoto

Suzuki

2017

J. Org. Chem.

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Perfluororubrene (PF-RUB) has been synthesized by cycloaddition of perfluorinated 1,3-diphenylisobenzofuran and 1,4-diphenyl-2,3-didehydronaphthalene followed by reductive deoxygenation. This method was easily applied for the synthesis of half-fluorinated rubrene (F-RUB). The electrochemical measurements and DFT calculations indicate that perfluorination strongly lowers the HOMO and LUMO energies. Recrystallization and sublimation of PF-RUB gave two different crystals with planar and twisted conformations, respectively. In both cases, perfluorination leads to the formation of short C-F and F-F contacts and completely disrupts face-to-face π interactions. Single crystals of F-RUB were grown by sublimation, and twisted molecules display the two-dimensional π-stacking with a face-to-face distance of 3.54 Å.

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Vibrational modes and changing molecular conformation of perfluororubrene in thin films and solution

Cited by 5 publications

References 57 publications

Enhanced Stability of Rubrene against Oxidation by Partial and Complete Fluorination

Enhanced Stability of Rubrene against Oxidation by Partial and Complete Fluorination

Rubrene Versus Fluorine-Functionalized Rubrene Molecules on a Metal Surface: Self-Assembly, Electronic Structure, and Energy Alignment of a Monolayer on Ag(100)

Perfluorinated and Half-Fluorinated Rubrenes: Synthesis and Crystal Packing Arrangements

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