Exploring potentialities and limitations of stapled o‐oligo(phenyleneethynylene)s (o‐OPEs) as efficient circularly polarized luminescence emitters

Abstract

In this paper, we have studied the chiroptical properties of a family of o-oligo(phenyleneethynylene) (o-OPE) derivatives with different steric hindrance. Experimental results show high dissymmetry factors (g abs and g lum up to 1.1 × 10 −2 ) and very similar electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) for all the derivatives that make this basic o-OPE scaffold a robust pure organic emitter. Vibrational circular dichroism spectra are used to characterize conformational properties in solution. Density functional theory and time-dependent density functional theory calculations support experimental results also proving that ECD and CPL are almost exclusively linked to helical moiety and not to size or conformation of substituents. As chiroptical properties of these emitters are independent of substituents, this OPE scaffold can be used as basic skeleton for the design of sensing probes with high CPL efficiencies.

Pyrene-Containing ortho-Oligo(phenylene)ethynylene Foldamer as a Ratiometric Probe Based on Circularly Polarized Luminescence

“…A total bias of such equilibrium is desired in order to maximize the chiroptical responses as they mainly depend on the helix. An exploration of this effect in simple derivatives led us to conclude that the very robust g lum value around 10 –2 of ( P ,1 S ,2 S )- 1 was retained and was independent of any substitution in the diol . This observed relationship between the helix and the tether suggests that they were stereochemically coupled.…”

“…An exploration of this effect in simple derivatives led us to conclude that the very robust g lum value around 10 –2 of ( P ,1 S ,2 S )- 1 was retained and was independent of any substitution in the diol. 7 This observed relationship between the helix and the tether suggests that they were stereochemically coupled. That is, strong variations of the OPE helicity could, in principle, affect the spatial arrangement of a pyrene-functionalized tether and vice versa.…”

Recent Progress on Circularly Polarized Luminescent Materials for Organic Optoelectronic Devices

“…Additionally, each enantiomer exhibited mirror‐image CD spectra with clear cotton effects, and opposite CPL signals were observed with the g lum value about 1.7 × 10 −3 . Since unsymmetrical disilane‐bridged cyclophanes could produce strong emission through intramolecular charge transfer between the donor and the acceptor moieties, the enantiomer of 138 could be employed as the green‐emitting dopant in OLED device . The device with the structure as shown in Figure S4 (Supporting Information) was fabricated and possessed an EQE of 0.36% with the power of 90 µW cm −2 at a current density of 9 mA cm −2 , where α‐NPD, dPVBi, and BCP denote N , N′ ‐di‐1‐naphthyl‐ N , N′ ‐diphenylbenzidine, 4,4′‐bis(2,2′‐diphenylvinyl)‐1,1‐biphenyl, and bathocuproine, respectively.…”

Extended enantiopure ortho-phenylene ethylene (o-OPE)-based helical systems as scaffolds for supramolecular architectures: a study of chiroptical response and its connection to the CISS effect

“…Thus, we have developed two strategies to obtain enantiopure folded fully conjugated helical systems: the first based on the use of chiral sulfoxides [59][60] and, secondly, the use of chiral staples, demonstrating that enantiopure P/M helixes can be also prepared by an efficiently chirality transfer from a chiral staple to the o-OPE core, including even double staples to avoid racemization processes. [61][62][63][64] However, those later systems could be synthesized with only one turn and a half. 65 All the above approaches provide structures with remarkable chiroptical responses in ECD, CPL and VCD.…”