Revealing Crystallization-Induced Blue-Shift Emission of a Di-Boron Complex by Enhanced Photoluminescence and Electrochemiluminescence.

Elucidating the effects of crystallization-induced blue-shift emission of a newly synthesized di-boron complex (DBC) by enhanced photoluminescence (PL) and electrochemiluminescence (ECL) in the annihilation pathway was realized for the first time. The 57 nm blue-shift and great enhancement in the crystalline lattice relative to the DBC solution were attributed to the restriction of intramolecular rotation (RIR) and confirmed by PL imaging, X-ray diffraction, as well as DFT calculations. It was discovered that ECL at crystalline film/solution interfaces can be further enhanced by means of both co-reactant route and RIR. The RIR contributions with co-reactant increased ECL up to 5 times more. Very interestingly, the co-reactant system was found to give off a red-shifted light emission. Mechanistic studies reveal that a difference between location of the ECL in the co-reactant route and that in the annihilation pathway leads to an alternative emission wavelength.