Two-Component Orderly Molecular Hybrids of Diphenylanthracene: Modulation of Solid-State Aggregation toward Tunable Photophysical Properties and Highly Enhanced Electrochemiluminescence

Development of high-efficiency solid-state electrochemiluminescence (ECL) devices plays an important role in illumination, chemical/biological trace detection, and clinical tests. However, effective molecular systems with high ECL output are still limited due to the requirements of high photoactivity and electron transfer ability. Herein, it is shown that the formation of two-component molecular hybrids of diphenylanthracene (DPA) can largely enhance the ECL properties. First, four new DPA-based cocrystals are prepared using a facile solid-state grinding method. The as-prepared samples (powder and single crystal) present tunable photophysical and photonic properties (such as alternations of wavelength, fluorescence lifetime, photoluminescence quantum yield, and two-photon emission). Moreover, the polarized fluorescence and 1D/2D optical waveguide behaviors can be obtained due to the orderly assembly of the molecular chromophores and regular crystal morphology. Second, the DPA-based cocrystals have been fabricated into solid-state electrodes, which present magnified ECL signal intensity (>20 fold) relative to the pristine DPA, as a result of alternation of molecular aggregation fashions and improved intermolecular electron transfer between DPA and the coassembled units as confirmed from experimental and computational views. The DPA-based solid-state electrode can be further used as an ECL sensor toward temperature response and nitrate detection with high selectivity and low detection limit. Therefore, this work not only develops new molecular hybrids with adjustable photophysical performances and potential ECL sensor applications but also supplies a detailed understanding on the relationship between molecular stacking and electron transfer within the orderly molecular donor/accepter solids.