Self-revealing kinetically captured self-assembly of a N,N′-diphenyl-dihydrodibenzo[a,c]phenazine derivative

Abstract

Real-time, in situ, and visual characterization of non-equilibrium self-assembly processes is of great interest because of its importance, but it is challenging because of its complexity. Herein, we construct an adduct of vibration-induced emission (VIE)-active N,N′-diphenyl-dihydrodibenzo[a,c]phenazine (DPAC) and a cysteine derivative, i.e., di-tert-butyl 3,3′-disulfanediylbis(2-formamidopropanoate) (Cys^tBu), where DPAC functions as both a hydrophobic motif and fluorescent reporter while Cys^tBu acts as a hydrophilic group and hydrogen-bonding moiety. The resulting adduct DPAC-Cys^tBu-DPAC is capable of self-assembly and gradually transforming from a non-equilibrium non-dissipative metastable state to a thermodynamically stable state over time. By virtue of the conformation-dependent emission feature of the VIE fluorogen, the whole self-assembly process can be self-monitored by the continuous fluorescence changes from orange-red to blue, in an in situ, real-time, and visual fashion. Moreover, benefiting from the chirality of Cys^tBu and the conformation-flexibility of DPAC, circularly polarized luminescence (CPL) with an asymmetry factor (g_lum) of up to 7.1 × 10⁻² is induced as the kinetically-captured aggregates are transformed into columnar assemblies in a thermodynamically stable state. This work not only opens a new avenue for the real-time and in situ characterization of the self-assembly processes, helping to pave the way for the preparation of complex out-of-equilibrium supramolecular functional systems, but also provides a new type of CPL material.