title: Self-assembly solid-state enhanced red emission of quinolinemalononitrile: optical waveguides and stimuli response.
abstract: The fluorescence of luminescent emitters is often quenched in the solid state, because of the typical aggregation-caused quenching (ACQ) effect, which is a thorny obstacle to high-performance organic optoelectronic materials. The exploration of solid-state enhanced long wavelength, red-emitting chromophores, especially possessing one-dimensional (1D) assembly features, is of great importance. Interestingly, an excellent solid-state enhanced red emission system (denoted as ED) based on quinolinemalononitrile has been developed via the delicate modification of the conventional ACQ dicyanomethylene-4H-pyran (DCM) derivative (denoted as BD) through crystal engineering. ED exhibits extraordinary self-assembly property in a variety of solvents, even realizing the "waving ribbons" with a length of 6 mm and a diameter of 10 μm. Crystal analysis shows that the CH···π and CH···N supramolecular interactions of ED contribute to the twisted self-assembly solid-state enhanced emission phenomenon. However, for BD, strong face-to-face stacking leads to fluorescence quenching in the solid state. Because of such easy assembly and strong solid-state emission properties, application for optical waveguides of ED is realized with a low optical loss. Stimuli-responsive behavior is also elaborated with color change between orange and red by grinding/fuming or pressing/heating.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai, People's Republic of China.
authors.forename: Chuanxing
authors.initials: C
authors.lastname: Shi
authors.forename: Zhiqian
authors.initials: Z
authors.lastname: Guo
authors.forename: Yongli
authors.initials: Y
authors.lastname: Yan
authors.forename: Shiqin
authors.initials: S
authors.lastname: Zhu
authors.forename: Yongshu
authors.initials: Y
authors.lastname: Xie
authors.forename: Yong Sheng
authors.initials: YS
authors.lastname: Zhao
authors.forename: Weihong
authors.initials: W
authors.lastname: Zhu
authors.forename: He
authors.initials: H
authors.lastname: Tian