Multiemission tunability with ultralong and time–dependent room-temperature phosphorescence from isophthalic acid-decorated carbazole by coordination–induced crystallization

Abstract

Two building blocks with triplet exciton generation of carbazole and isophthalic acid were integrated together to yield CzIP, and the strategy of coordination-induced crystallization was adopted, two supramolecular coordination frameworks 1 and 2 were synthesized with CzIP as ligand. Interestingly, several stacking types of CzIP molecules could be tuned and achieved, these compounds not only generate efficient fluorescence, but also exhibit the long room temperature phosphorescence (RTP), the afterglow lifetime is up to 0.76 s of compound 1 with phosphorescence quantum yield (9.5%). Significantly, compound 1 and 2 not only exhibit the single-phased white emission, but also present the time-dependent afterglow color, showing the greatly promising for anti-counterfeiting application. Experimental results and theoretical calculations reveal that the molecule stacking play a leading role in the optical properties and coordination bonds show the strong power to regulate the conformation and arrangement of organic molecules, and C–H···π bond can also play a significant role in the generation of long persistent phosphorescence. Importantly, integrating two phosphorescent chromophores with intermolecular charge transfer in a single–component organic molecular opens an efficient way to design the time-dependent room–temperature phosphorescence.