Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

Abstract

SummaryThe pseudo five-component Sonogashira–Glaser cyclization synthesis of symmetrically 2,5-diaryl-substituted thiophenes is excellently suited to access thienyl-bridged oligophenothiazines in a one-pot fashion. Three thienyl-bridged systems were intensively studied by UV–vis and fluorescence spectroscopy as well as by cyclic voltammetry. The oxidation proceeds with lower oxidation potentials and consistently reversible oxidations can be identified. The Stokes shifts are large and substantial fluorescence quantum yields can be measured. Computational chemistry indicates lowest energy conformers with sigmoidal and helical structure, similar to oligophenothiazines. TD-DFT and even semiempirical ZINDO calculations reproduce the trends of longest wavelengths absorption bands and allow the assignment of these transitions to possess largely charge-transfer character from the adjacent phenothiazinyl moieties to the central thienyl unit.

Triazolyl Conjugated (Oligo)Phenothiazines Building Blocks for Hybrid Materials—Synthesis and Electronic Properties

“…Our synthesis of linear conjugated triazolylsubstituted (oligo)phenothiazine precursors for hybrid materials’ synthesis bearing triethoxylsilyl propyl groups commences from ethynylated (oligo)phenothiazines 1 [ 31 , 32 , 33 , 34 ]. Mono- and diethynylated (oligo)phenothiazines 1 undergo the CuAAC at room temp in DMF with (3-azidopropyl)tri-alkoxysilanes 2 [ 35 ] to give conjugated triazolylsubstituted (oligo)phenothiazines 3 in excellent yield as oils ( Scheme 1 ).…”

Multicomponent synthesis of chromophores – The one-pot approach to functional π-systems

“…The phenothiazine moiety has also been implemented in linear (Sailer et al, 2008) or cyclic (Memminger et al, 2008) oligomer topologies as well as diphenothiazinyl dumbbells linked by heterocycles (Franz et al, 2009;Hauck et al, 2010;Jahnke et al, 2014). The synthesis of symmetrical thienyl-bridged oligophenothiazine dumbbells 106 is feasible via a consecutive pseudo five-component Sonogashira-Glaser cyclization sequence (Scheme 20C) (Urselmann et al, 2016).…”

“…(B) One-pot sequence to synthesize disubstituted phenothiazine-triazine dyes 105 (Kloeters et al, 2022). (C) Pseudo five-component Sonogashira-Glaser cyclization synthesis of thienyl-bridged oligophenothiazines 106 (Urselmann et al, 2016). (D) One-pot LiForK synthesis of a 3,7-diacceptor substituted phenothiazine 107 (May and Müller, 2020).…”

Dithieno[1,4]thiazines and Bis[1]benzothieno[1,4]thiazines—Organometallic Synthesis and Functionalization of Electron Density Enriched Congeners of Phenothiazine

“…Phenothiazines exhibit, despite pronounced biological activity [15], fully reversible one-electron oxidations at low potentials [16], extraordinarily stable radical cations [17,18], and simultaneously luminescence, which is rather uncommon but nevertheless quite valuable for numerous applications. For instance, OLEDs [19][20][21] as well as redox switchable luminophores [10,22] have been developed based on phenothiazines. Moreover, phenothiazines are promising candidates for photovoltaics in efficient bulk-heterojunction solar cells and Grätzel-type solar cells (DSSC) [23][24][25][26][27].…”