We report our investigation on the nanorods of two newly synthesized substituted pentacenes, d 4 -substituted (2,3-X 2 -9,10-Y 2 ) pentacene with X = Y = methoxy group (MOP) and X = F, Y = methoxy (MOPF), by using X-ray photoemission spectroscopy (XPS), near edge X-ray absorption fine structure (NEXAFS), and atomic force microscopy (AFM). The nanorods were deposited on Au(111) single crystals. Energy dependent photoemission spectra show complex features, including a rich satellite structure that we have analyzed in detail by using a bestfit procedure applying constraints based on stoichiometry, electronegativity, and bond strength. This analysis reveals the presence of surface core level shifts due to the high electronegativity of the fluorine atoms. The distinctive features of growth and morphology of the nanorods are subjected to a template effect by the substrate lattice geometry, leading to morphological well-organized assemblies. Fluorine atoms play an important role not only in the electronic structure but also in the morphology of the nanorod assemblies.

The thermal and photochemical syntheses of 2,3,9,10-tetrafluoropentacene (F4PEN) from 6,13-etheno bridged precursors were investigated computationally and experimentally. A computational study of the retro-Diels-Alder reaction to give 2,3,9,10-tetrasubstituted pentacenes and pyridazine revealed a linear correlation between barrier height and substituent constant (σ) indicative of an electronic effect that could diminish the yield of electron-poor 2,3,9,10-tetrasubstituted pentacenes in this reaction. The photochemical route from the corresponding bridged α-diketone yields F4PEN, which was characterized photophysically, electrochemically, and structurally. The compound crystallizes in a herringbone motif with quite short intermolecular F-F contacts that are, however, only very weakly bonding according to computations. The electrochemical and photophysical data show that the HOMO-LUMO gap of F4PEN is increased compared to that of PEN. This is due to an increase of the oxidation potential of F4PEN by 0.18 V in combination with an essentially unchanged reduction potential. The radical cation and dication of F4PEN could be generated in oxidizing solvents and characterized by optical spectroscopy and ESR or NMR, respectively. Both charged F4PEN species persist for days in solution.

The boron-nitrogen-boron (BNB) zigzag edged benzo[fg]tetracene is accessible from 4-butyl-2,6-diphenylaniline in four steps in good yields. The two mesityl groups stabilize the boron centers toward nucleophilic attack and result in two enantiomeric forms in the solid state. The title compound has a large optical gap, shows blue fluorescence, and is quite resistant toward oxidation and reduction.

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6,13-Bis[tri(isopropyl)silylethynyl]pentacene is a prototypical molecule for organic semiconductor and photovoltaic materials, which makes its electrochemical (redox) properties highly interesting. However, previous cyclic voltammetric studies have provided only limited information. Kinetic and persistence information and identification of the oxidation product(s) and their further reaction or oxidation have not been reported. Thus, an extended electrochemical and spectroscopic investigation of this compound was conducted in CH Cl and THF electrolytes at Pt electrodes. The electrochemically and chemically generated radical cation of the title compound was characterized by using ESR and UV/Vis/NIR spectroscopy and quantum-chemical modeling. In CH Cl , further oxidation to a dication with chemical reversibility at fast timescales but follow-up reactivity at slow timescales was observed. Pertinent parameters of the electron transfers (formal potentials E , electron transfer rate constants k , electron stoichiometry n) were determined. The diffusion coefficients, D, in the two electrolytes were estimated from electrochemical and pulse gradient spin echo (PGSE) NMR spectroscopy data. Simulations of cyclic voltammograms supported the proposed oxidation mechanism and allowed the estimation of further reaction parameters.