Donor–Acceptor Functionalized Luminescent Hairpin Peptides: Electrochemiluminescence of Pyrene/Phenothiazine-Substituted Optically Active Systems

Abstract

Three electrochemiluminescent octapeptides containing pyrene and phenothiazine chromophores are investigated via their spectral and electrochemical properties. The measurements prove the formation of excimers and exciplexes, which are generated intramolecularly on photonic activation and intermolecularly on electrochemical activation. The molecules investigated are of interest for optoelectronical applications such as the fabrication of new biosensors.

ECL—Electrochemical luminescence

“…249 Donor-acceptor functionalized luminescent hairpin peptides containing pyrene/ phenothiazine-substituents display complex ECL including monomer, exciplex and excimer emission. 250 Two of the peptides showed intramolecular chromophorebased through space interactions resulting in excimer bands, while another displayed bands characteristic of exciplex formation. Since there was a relationship between structural features and signal response, it was proposed that these peptides might prove useful for probing molecular recognition events.…”

Oligo(phenothiazine)s: Twisted Intramolecular Charge Transfer and Aggregation-Induced Emission

“…Among numerous π systems suitable for optoelectronic applications, electron-rich moieties such as phenothiazine are of great interest for their high first oxidation potentials, 18 and the favorable electronic properties of phenothiazine have led to applications such as electrophore probes in supramolecular assemblies and sensor studie. 19,20 The rotation of divinylanthracene may contribute to the formation of ICT state in polar aggregation is not complete in the case. Nevertheless, the enhanced emission of the two compounds possessing ICT states possibly originate from the restraint of both intramolecular rotation and the formation of low fluorescent state, such as ICT state.…”

“…Here we introduced phenothiazines as electron donating groups to form the D−π–D structure in DSA backbone to get two AIE oligomers AnPHZ2 and AnPHZ4 (see Figure ). Among numerous π systems suitable for optoelectronic applications, electron-rich moieties such as phenothiazine are of great interest for their high first oxidation potentials, and the favorable electronic properties of phenothiazine have led to applications such as electrophore probes in supramolecular assemblies and sensor studie. , The rotation of divinylanthracene may contribute to the formation of ICT state in polar solvents. Indeed, the fluorescence spectra of both AnPHZ2 and AnPHZ4 exhibited obvious solvatochromism; i.e., in polar solvents (such as acetone, dimethylformamide (DMF), and acetonitrile) a red-shifted emission and severely decreased quantum yield (Φ F ) are observed in comparison to those in cyclohexane and toluene.…”

Novel Luminescent Ionic Adducts Based on Pyrene-1-sulfonate

“…Analogous to porphyrins, pyrene derivatives constitute a class of attractive and thoroughly investigated solvatochromic fluorophores widely applied in optoelectronics, biochemistry, and sensor fields. These compounds are characterized by long excited-state lifetime and, in concentrated solution and in the solid state, lead to characteristic excimers because of self-association phenomena. − Furthermore, pyrene acts as a probe for the local environment polarity because the intensity ratio of the first to third vibronic emission bands (I/III ratio) is very sensitive to the solvent polarity . On the basis of these considerations, pyrene sulfonate anions were chosen for the development of novel photoluminescent ILs.…”