5‐(Hetero)aryl‐Substituted 9‐Hydroxyphenalenones: Synthesis and Electronic Properties of Multifunctional Donor–Acceptor Conjugates

Abstract

5-(Hetero)aryl-substituted 9-hydroxyphenalenones (9-HP) can be readily synthesized by Suzuki coupling of 5-bromo 9-HP with (hetero)aryl boronic acid (derivatives) without protection of the hydroxyl functionality in moderate to excellent yields (57-94 %). A library of 5-(hetero)aryl substituted 9-HP with broad substituent variation was studied with respect to their electronic properties (absorption and emission spectroscopies and cyclic voltammetry) and their computed electronic structures. All compounds show reversible reductive potentials between -1230 and -1110 mV and the donor-substituted representatives possess irreversible oxidation potentials around 600 mV. Compounds with electron-rich donors even show reversible oxidation potentials. Especially the donor-substituted 9-HPs display emission bands between 466 and 567 nm with quite large Stokes shifts (up to 4100 cm ). TD-DFT calculations nicely reproduce the spectroscopic data and Hammett correlations underline a pronounced resonance substituent influence on the photophysical properties.

Synthesis and Physical Properties of Trioxotriangulene Having Methoxy and Hydroxy Groups at α-Positions: Electronic and Steric Effects of Substituent Groups and Intramolecular Hydrogen Bonds

“…Since the methyl groups were removed from 2a – , the TOT skeleton was planar, and the O α and O α′ atoms were located on the π-plane (Figure d). C–O bond lengths of the oxo groups in 2a – and 2b – were 1.239–1.259 Å and 1.288–1.296 Å, respectively (Table S4), and the latter of which are close to those of 9-hydroxyphenalenone and its derivatives forming intramolecular H bonds between two oxygen atoms. It should be noted that these systems may exhibit interesting dielectric properties originating from the dynamic properties of protons between the two oxygen atoms. , In the crystal packing of 2a – salt, the molecules did not form any π-stacking structures due to the steric effect of the MeO groups (Figure S7).…”

Room‐Temperature Reversible σ‐Dimerization of a Phenalenyl Radical

“…Commercially available reagents were purchased and used upon arrival. Bis(pentafluorophenyl)boron chloride [ 14 ] and 5‐bromo‐9‐ hydroxy‐1 H ‐phenalen‐1‐one [ 15 ] were synthesized according to the reported procedures. Cyclic voltammetry was performed on a CHI660E electrochemical workstation with platinum as the working electrode and Ag/AgNO 3 (0.1 mol/L in CH 3 CN) as the reference, and the measurement was carried out under a nitrogen atmosphere.…”

Preservation of the donor–acceptor character of a carbazole–phenalenone dyad upon adsorption on Pt(111)

“…15,16 Recently 5-(hetero) aryl substituted conjugated 9-HP dyads were successfully synthesized in a modular fashion and their ensemble electronic ground and excited state properties were studied in detail. 17 However, here the delocalized donor and acceptor p-systems of the studied 5-[4-(9H-carbazol-9-yl)benzyl]-9-hydroxy-1H-phenalen-1-one (CBHP) are separated electronically by an aliphatic methylene bridge which introduces a twist angle between acceptor and donor and breaks the conjugation. In the following, single CBHP molecules will be analyzed on the Pt(111) surface by high-resolution STM in order to reveal their exact conformation and thus, their adsorption behavior.…”