Tuning Electrochemiluminescence Color Through Single Molecular Crystals

ABSTRACT Tuning electrochemiluminescence (ECL) color is of great interest for multicolor imaging and multiplexed bioanalysis. While existing methods largely rely on synthesizing multiple luminophores, here we demonstrate a novel strategy that modulates ECL emission through a molecular crystal (MC) waveguide, achieving color control with just one luminophore. Through the integration of a rod‐shaped MC with a gold‐coated micropipette electrode (MPE), a controllable electronic‐photonic device was fabricated, enabling precise regulation of light propagation from MPE orifice (i.e., ECL input) to MC terminal (i.e., ECL output). Red ECL generated from tris(2,2’‐bipyridyl)ruthenium (Ru(bpy) 3 2+ ) undergoes longitudinal propagation through the MC waveguide and exits from its terminal with negligible change in color. It is thus termed “Red Input/Red Output”. While replacing Ru(bpy) 3 2+ with a luminol analogue, 8‐amino‐5‐chloro‐7‐phenylpyrido[3,4‐d]pyridazine‐1, 4(2H, 3H)‐dione (L012), it produces blue ECL at MPE orifice, which can be regulated by MC waveguide and converted to green output at MC terminal, thus achieving dual‐color ECL emission from one luminophore via the so‐called “Blue Input/Green Output” mode. On the other hand, MC can also function as a long‐pass filter that allows the transmission of red light while blocking blue light. This color variation controlled by the MC waveguide demonstrates the promise for developing micro‐spectral filters and multicolor ECL biosensors.