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

Abstract

The mechanochromic properties of two acridine heterocyclic derivatives with a donor-acceptor configuration, 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), were investigated. The effect of different grinding time (10 and 20 min) and pre-heating temperature (−10, 100, and 120 °C) on the mechanochromic performance of DpAn-InAc and DpAn-BzAc were analyzed. The average red shift of the emission peak was 18 nm for DpAn-InAc powder under grinding stimuli, with the long grinding time (20 min) bringing the greatest shift, while both the highest (120 °C) and the lowest (−10 °C) pretreat temperature brought a greater impact on the luminescent peak. On the contrary, the ground DpAn-BzAc preheated at 100 °C showed the maximum wavelength shift, which was ascribed to the lower glass transition temperature of DpAn-BzAc. Meanwhile, the discolored sample could be recovered by ethanol fumigation, proving that the discoloration was reversible. X-ray diffractograms revealed that under the anisotropic force, the microcrystalline structure of DpAn-InAc and DpAn-BzAc were destroyed, resulting in the shift of the fluorescence peak. The fluorescence shift of DpAn-BzAc was more obvious than that of DpAn-InAc, while its recovery was inferior compared to DpAn-InAc, which was due to its looser molecular structure. Finally, DpAn-InAc and DpAn-BzAc were applied in delivering rewritable encrypted information and both of the two molecules have shown capabilities in transmitting coded information. This work sheds light on using the molecule with donor-acceptor molecular structure in the stimuli-responsive field, and shows their potential application in transmitting encrypted information.