Pre‐Planarized Triphenylamine‐Based Linear Mixed‐Valence Charge‐Transfer Systems

Abstract

Three linear dimers with two redox‐active planarized triphenylamines were synthesized and their structures verified by X‐ray crystallography. Their radical cations, which exhibit electron self‐exchange between the two redox centers, are of great interest. This process was thoroughly investigated by means of electron paramagnetic resonance spectroscopy, absorption spectroscopy, and (time‐dependent) density functional theory calculations. A comparison of the key parameters of electron transfer with non‐planarized nitrogen‐centered building blocks emphasizes the impact of using redox centers with low internal reorganization energies. However, the distance‐dependence attenuation factor of the super‐exchange mechanisms remains similar.

Control of Electron Transfer Processes in Multidimensional Arylamine-Based Mixed-Valence Compounds by Molecular Backbone Design

“…They have been exploited as fundamental components in diverse optoelectronic and biological applications, such as organic light-emitting diodes (OLED), , organic field-effect transistors (OFET), electrochromic and electrofluorochromic devices (ECDs and EFCDs), − and fluorescent probes in bioimaging field. − In particular, a large variety of organic molecules have been synthesized for being used as hole-transporting materials (HTM) in organic photovoltaics as dye-sensitized solar cells (DSSCs) , and perovskite solar cells (PKSC). − Organic mixed-valence systems (MVs) constitute excellent examples to study the basic aspects of charge-transfer reactions and their implication in the field of molecular electronics. To this purpose, it is indeed crucial to (i) devise molecules allowing an intramolecular electron or hole transfer between at least two redox sites linked by a bridge and (ii) establish rules for the prediction and control of the electron propagation through this bridge. , Arylamine fragments are the most used redox centers in the construction of promising HTMs. − They exhibit a well-defined N •+/0 process in a relatively low potential region, good stability of radical species, and the ability to transport positive charge efficiently. In the last years, different studies have considered arylamine-based linear MVs as versatile molecular models for investigating the basic electron- and/or charge-transfer (ET/CT) phenomena and the strength of the intramolecular electron coupling between two redox centers. − On the contrary, charge-transfer phenomena in arylamine-based multidimensional MVs have not been much studied, − although a large number of these molecular structures have been synthesized and used as HTMs in various optoelectronic devices. ,, …”

A Chiral Molecular Cage Comprising Diethynylallenes and N‐Heterotriangulenes for Enantioselective Recognition

“…We observe two reversible oxidation waves at +0.41 and +0.44 V (vs. ferrocene/ferrocenium (Fc/Fc + )), respectively, which can be attributed to the formation of the double radical cationic species (Figure S12). [49] In comparison to parent unsubstituted N ‐HTA ( S1 ), with an oxidation wave centered at +0.34 V, an anodic shift in cage ( M ) 6 ‐ 3 appears as a result from the moderate EWG effect of the DEA units. These finding holds considerable promise for this system to be employed as a potential redox sensing agent.…”

“…[40][41][42][43][44][45] Besides exploring uncharted waters, N-HTA are also of interest given their solid candidacy for next-generation optoelectronic materials, [46][47][48] and properties such as reversible redox chemistry. [49] Here we present the synthesis and full characterization of an organic covalent chiral cage composed of enantiopure DEAs and electron-rich dimethylmethylene-bridged N-HTAs together with the evidence for its enantioselective sensing ability in solution.…”

“…[ 40 , 41 , 42 , 43 , 44 , 45 ] Besides exploring uncharted waters, N ‐HTA are also of interest given their solid candidacy for next‐generation optoelectronic materials,[ 46 , 47 , 48 ] and properties such as reversible redox chemistry. [49] …”

Vorplanarisierte Triphenylamin‐basierte lineare gemischtvalente Ladungstransfersysteme

“…ORTEP-Diagramm des DTA( oben), des DTB (Mitte) und des DTT (unten;t hermische Ellipsoide mit 50 %W ahrscheinlichkeit; Wasserstoffe sind nicht dargestellt). [36] Übersichtd er vorhandenen Torsionswinkel C und AEC-N-C/(a, b, g)-Winkel. [32] grçßer als die Hyperfeinaufspaltung,was deren Beobachtung verhindert.…”