Flapping Peryleneimide as a Fluorogenic Dye with High Photostability and Strong Visible‐Light Absorption

Abstract

Flapping fluorophores (FLAP) with a flexible 8π ring are rapidly gaining attention as a versatile photofunctional system. Here we report a highly photostable “flapping peryleneimide” with an unprecedented fluorogenic mechanism based on a bent‐to‐planar conformational change in the S1 excited state. The S1 planarization induces an electronic configurational switch, almost quenching the inherent fluorescence (FL) of the peryleneimide moieties. However, the FL quantum yield is remarkably improved with a prolonged lifetime upon a slight environmental change. This fluorogenic function is realized by sensitive π‐conjugation design, as a more π‐expanded analogue does not show the planarization dynamics. With strong visible‐light absorption, the FL lifetime response synchronized with the flexible flapping motion is useful for the latest optical techniques such as FL lifetime imaging microscopy (FLIM).

Fluorescent Flippers: Small‐Molecule Probes to Image Membrane Tension in Living Systems

“…Probes that deplanarize by bending rather than twisting, referred to as flappers, [135–138] papillons [139, 140] and the like, report on membrane organization by changes of the ratio of dual emission (Figure 13Cc, Ce), that is the viscosity‐dependent kinetics of excited‐state planarization (Figure 13Cd). Flipper‐like ground‐state planarization in equilibrium by physical compression was conceivable also for the bent counterparts but so far not observed, presumably because energy demands are too high (Figure 13Cf) [135, 139, 140] …”

Anthrazoline Photocatalyst for Promoting Esterification and Etherification Reactions via Photoredox/Nickel Dual Catalysis

“…[ 13 ] Large polycyclic heteroaromatics containing imine nitrogens have shown special merits in photocatalysis. Their extended planar π‐conjugation could result in: (1) improved electron affinity; [ 14 ] (2) substantial improvement in thermostability and photostability; [ 15 ] (3) ability to tune the electronic and optoelectronic properties by protonation or metal ion complexation. [16] Recently, we developed a series of anthrazoline‐derived chromophores as highly efficient photosensitizers, by the merger of Ni(II) complex in promoting C—N bond formation.…”

Flapping motion as a fluorescent probe for assembly process involving highly viscous liquid-like cluster intermediates during evaporative crystallization

“…The environment-dependent fluorescence color changes can be utilized as fluorescence probes for viscosity and free volume in the medium. Previously, micro-viscosity probes for viscous mediums [10], the resin polymerization process [8], compression of a monolayer at an air-water interface [11], liquid-crystal phase transition [12], and polymer-free volume [13] have been reported.…”

“…In addition to the fluorescence monitoring, the energy diagram in the ground and excited states and their ultrafast dynamics were evaluated by the computational calculations and time-resolved spectroscopies. [8,10,23] In this study, we observed the fluorescence spectral changes of a FLAP during the solvent evaporation process to monitor the nano-environment changes, using a conventional multi-channel spectrometer and HSC imaging. [18,24] An HSC is a camera used to obtain spectral information at each pixel together with spatial distribution, which enables the observation of the molecular aggregation dynamics of the evaporative crystallization process in realtime.…”