We designed and synthesized the mono bay functionalized perylenediimide (PDI) derivative PDI-DMEA which undergoes self-assembly to form a nanorod morphology. The diameter of these nanorods is in the range of 150-300 nm and the length extended up to the mm range. These nanorods on interaction with Cu2+ ions transformed into spherical aggregates having a diameter of 350-600 nm in accordance with DLS studies. In solution, PDI-DMEA shows a blue shift of the internal charge transfer (ICT) absorption band from 605 to 570 nm along with a hyperchromic effect at 570 nm, in the presence of 0.7 equivalents of Cu2+ ions. The addition of 2 equivalents of Cu2+ ions results in complete disappearance of the ICT band at 570 nm and appearance of a normal absorption band of PDI at 515 nm (a visual colour change from colourless to yellow). On the other hand PDI-DMEA shows a strong fluorescence 'turn-on' response at 537 and 573 nm on addition of higher equivalents of Cu2+ ions. Thus, PDI-DMEA represents several examples of molecular switches such as 'OFF-ON-OFF' and 'ON-OFF-ON' at 570/515 nm (Cu2+, absorbance), and 'OFF-ON' at 570 nm (Fe2+, absorbance) and 537 nm (Cu2+, fluorescence) and thus offers the possibility for developing NOR, OR, INH and TRANSFER logic and complimentary logic circuits. Moreover, PDI-DMEA and the PDI-DMEA-Cu2+ complex show fluorosolvatochromism which helps to develop a colour array for differentiating organic solvents. The detailed mechanism of interaction of Cu2+ and Fe2+ with PDI-DMEA, confocal laser scanning microscopic studies, dynamic light scattering, H-1 NMR titration and reversibility are discussed.
