Rational design of red AIEgens with a new core structure from non-emissive heteroaromatics.

Ming Chen,Nelson L C Leung,Ryan T K Kwok,Junkai Liu,Herman H Y Sung,Baixue Li,Ben Zhong Tang,Jacky W Y Lam,Ian D Williams,Tsz Shing Cheung,Lucia Viglianti,Anjun Qin,Xianglong Hu

doi:10.1039/c8sc02810a

Abstract

The development of new aggregation-induced emission (AIE) systems is a hot research topic, from which functional materials with diversified structures and properties are derived. Here, based on rare, non-emissive and highly electron-withdrawing heteroaromatics of 1,4,5,8-tetraazaanthracene (TAA), experimental and theoretical studies reveal that attaching phenyl rotors to TAA is crucial to creating a new N-type AIE core structure. Furthermore, by covalent attachment of electron-donating aromatic amines to the peripheries of the AIE core, red AIEgens could be obtained readily, which exhibit excellent photostability for long-term lysosome tracking. This work not only provides a new strategy to design heterocycle-containing AIEgens from non-emissive heteroaromatics but also stimulates more their applications as bio-imaging materials.

Highlights

The exploitation of aggregation-induced emission luminogens (AIEgens) is both of great academic and practical importance and can stimulate rapid development in the areas of optoelectronics, bio-imaging, nanoscience, etc.[1,2] To date, hundreds of AIEgens have been developed
Since the bondstretching vibration only takes places with a distance of ca. 1 Aalong the bond axis, which is relatively insensitive to the aggregation environment, the contribution from the changes of the dihedral angle decreased from 32% to 24% upon aggregation into the crystal state, which was considered as the main contributor affecting non-radiative decay channels between the two states. All these results indicated that the restriction of rotation of the phenyl ring of TAA-4P played an important role in determining the crystallizationinduced emission (CIE) effect
Our study proved that: (1) attaching TAA with phenyl rotors can change the transition component from the n / p* transition to the p / p* transition, increasing the irradiative transition component of TAA derivatives and (2) the introduction of phenyl rotors into TAA facilitated the rotation of molecules in solution to dissipate energy a er excitation non-radiatively, while the motion was suppressed to open up the irradiative transition channel upon aggregation, endowing the derivatives with AIE activity

Summary

Introduction

The exploitation of aggregation-induced emission luminogens (AIEgens) is both of great academic and practical importance and can stimulate rapid development in the areas of optoelectronics, bio-imaging, nanoscience, etc.[1,2] To date, hundreds of AIEgens have been developed. Because TAA shows strong electron-withdrawing ability, it can help to construct a novel N-type AIE core to build red-emissive AIEgens via rational structural design.

Results

Conclusion