The construction of a multicolored mechanochromic luminogen with high contrast through the combination of a large conjugation core and peripheral phenyl rings

Abstract

Through the combination of a large conjugation core and peripheral phenyl rings, one mechanochromic (MC) luminogen (3) with multicolored and high contrast emission is facilely obtained. Luminogen 3 shows aggregation-induced emission (AIE) and crystallization enhanced emission (CEE). The emission of 3 can be switched between deep blue (432 nm, Φ_F = 42.2%), green (492 nm, Φ_F = 59.3%), and orange (584 nm, Φ_F = 0.4%) with high contrast in both color and efficiency through morphology tuning by heating, mechanical stimuli, and solvent fuming. The multicolored and high contrast MC emission of 3 affords its potential application in optical recording. A single luminogen of 3 can form a green or deep blue emissive background on a piece of weighing paper, and weak orange emissive letters could be obtained through writing on both backgrounds. Letters on the green background transfer to deep blue upon fuming with methanol, and those on the deep blue background transfer to green upon fuming with acetone. All the letters could be erased through grinding or heating at 160 °C.