Thermochromic properties of acridine heterocyclic derivatives with a donor-acceptor configuration

We investigated the thermochromic properties of two donor-acceptor type fluorescent molecules 10-phenyl-10-(4-(7,7,13,13-tetramethyl-7,13-dihydro-5H-indeno[1,2-b]acridin-5-yl)phenyl)anthracene-9(10H)-one (DpAn-InAc) and 10-(4-(5,5-dimethylbenzofuro[3,2-c]acridin-13(5H)-yl)phenyl)-10-phenylanthracen-9(10H)-one (DpAn-BzAc). In its powder-state, DpAn-BzAc showed obvious thermochromic properties, transitioning from green at room temperature (RT) to blue at 200 degrees C under ultraviolet light and from yellow at RT to white at 200 degrees C under natural light. In the film-state, the emission wavelength of the DpAn-InAc film blue-shifted 23 nm at 200 degrees C when using high-polarity acetonitrile as the solvent for spin-coating. The thermochromic phenomena of the DpAn-BzAc powder were ascribed to the molecular buildup-induced phase change under annealing, and the low-polarity solvents toluene and chloroform could recover this molecular variation. The thermochromism of the DpAn-InAc film resulted from the gradual crystallization and stabilization processes under annealing. The class of bipolar acridine heterocyclic derivatives with a donor-acceptor configuration shows promising applications in the field of thermochromism.