Synthesis and Electronic Properties of Sterically Demanding N-Arylphenothiazines and Unexpected Buchwald−Hartwig Aminations

Abstract

Phenothiazine is coupled under Buchwald-Hartwig conditions with bromo anthracenes and perylene as substrates to give phenothiazine-anthracene and phenothiazine-perylene dyads and triads. Investigation of the electronic properties of these sterically demanding N-aryl phenothiazines by absorption and emission spectroscopy, cyclic voltammetry, and DFT calculations revealed that the individual chromophores are decoupled in the electronic ground state but show unique electronic communication in the excited state. For the anthracenyl-bridged diphenothiazine an intense electronic coupling of the phenothiazinyl units is detected upon oxidation. Besides, attempts to synthesize phenothiazine compounds with even more sterically demanding aryl substituents in the 10-position under N-arylation conditions gave rise to the formation of quite unexpected products of arylation and/or oxidative coupling. The folding angle of the phenothiazine in a consanguineous series correlates well with the first oxidation potential.

Synthesis, Electronic, and Electro‐Optical Properties of Emissive Solvatochromic Phenothiazinyl Merocyanine Dyes

“…In addition, modular strategies have enabled straightforward accesses to structurally well-defined monodisperse electronically coupled oligophenothiazines with direct 3,7-ligation (Scheme 1) of the units. [14a, 24] Interestingly, the emission behavior of phenothiazine derivatives such as cyanoA C H T U N G T R E N N U N G (oligo)-phenothiazines, [14b] and diphenothiazine dumbbells bridged by carbo- [25] and heterocycles, [14c] and cruciforms [26] reveals enormous Stokes shifts and, thus, has aroused our interest for a deeper understanding of the excited-state structure and properties. Here, we report the syntheses and investigation of ground-and excited-state electronic properties of various phenothiazinyl merocyanines with tunable emission and redox properties.…”

Exciton Coupling Model for the Emergence of Second Harmonic Generation from Assemblies of Centrosymmetric Molecules

“…Based on a previously published crystal structure, TAQ forms a centrosymmetric, SHG-inactive crystal structure of symmetry, in which every monomer is in exactly the same orientation within the lattice and each monomer is centrosymmetric. 30 Considering a dimer formed from two monomers of identical orientation, the wave functions for the sum states will simply be identical but rescaled, and all of the difference states will be zero-valued. As such, the SHG activity of the TAQ dimer and crystal is interesting to interpret within the context of the exciton coupling model.…”

Macrocycles embedding phenothiazine or similar nitrogen and/or sulphur containing heterocycles

“…Due to these interesting properties phenothiazine derivatives are widely used for the obtaining of new materials such as: electroactive polymers [28][29][30], dyads and triads [31][32][33][34], cruciform fluorophores [35], molecular wires [36] or ligands for surface modifications [37][38][39]. Innovative redox-active materials were obtained with compounds showing two or more (up to seven) phenothiazines directly connected to each other [40][41][42][43] or via ethynyl or aryl units [44][45][46][47].…”