Dual-State Emission (DSE) in Organic Fluorophores: Design and Applications

Abstract

Organic luminescent materials have attracted significant attention in the past few years due to their fascinating photophysical properties. Implementing these emissive organic compounds is now being actively pursued in many applications in solution (i.e., sensors, bioimaging) or their solid forms (i.e., optoelectronic devices or data encryption). Despite significant advances in the development of emissive compounds, there has been an increasing quest in the past decade for materials where the emission is preserved in both states, dual-state emission (DSE). These compounds are expected to detonate a myriad of applications in the future. On this nascent topic, this work addresses several factors that increase the probability of obtaining the dual-state emission property based on the precedent reports showing this phenomenon. Therefore, this review identifies and organizes the different structural characteristics useful to obtain these compounds. In addition, it has been devised to motivate the discussion in the materials science community and hopefully incentivize the efforts of many research groups around the world toward the synthesis of new dual-state emitters.

Ionic Rigid Organic Dual-State Emission Compound With Rod-Shaped and Conjugated Structure for Sensitive Al3+ Detection

“…Recently, a rational molecular design strategy has been presented based on triphenylamine via theoretical calculation and practical verification by the Gong group ( Zou et al, 2022 ). However, although many efforts including various physical and chemical methods have been contributed to designing and exploring new DSE compounds, the research of DSE luminogens remains preliminary with relatively limited examples in the literatures ( Belmonte-Vázquez et al, 2021 ). There still exists a serious lack of a universal molecular design strategy for DSE luminogens.…”

D–A–D structured triphenylamine fluorophore with bright dual-state emission for reversible mechanofluorochromism and trace water detection

“…S4†). The relatively weak absorption at around 310 nm in the selected solvents except for acetonitrile (Ace) could originate from the locally excited π–π* transition of TPA units 26 and the major absorption at around 350 nm should correspond to the ICT transition between the TPA unit and the benzaldehyde core. 45 The ICT absorption in solvents remains unchanged with the change of solvent polarity, whereas the fluorescence exhibits obvious solvent-dependent emission.…”

The locations of triphenylamine and tetraphenylethene on a cyclohexyl ring define a luminogen as an AIEgen or a DSEgen

“…19 In this regard, π units are often coupled in a conjugated fashion to tune the electronic structures of the molecules, conferring high quantum yields and adjustable emission wavelength on DSEgens. 20 Interestingly, Liu et al reported a tetrahydropyrimidine (THP) compound by connecting multiple isolated aryl arms to a non-conjugated stator and observed strong solid-state emission, despite the absence of effective conjugation between those isolated aryl pendants. 21 We also achieved strong aggregate emission by attaching triphenylamine (TPA) and other aryl groups onto a saturated cyclohexyl ring.…”