Efficient modification of pyrene-derivative featuring third-order nonlinear optics via the click post-functionalization

A series of pyrene derivatives featuring nonplanar structures of N,N-didodecylanilino-substituted donor and TCNE/TCNQ adduct acceptors have been efficiently synthesized via formal [2+2] cycloaddition. As the efficient click by TCNE and TCNQ, the products show strong charge-transfer (CT) bands in the visible (near-IR region), potent redox activities, and related photophysical properties. UV/vis spectra and electrochemical studies show that the CT properties of these systems are readily tunable by strong cyano acceptor introduction on the nucleophile, which have a larger effect on the lowest unoccupied molecular orbital (LUMO). In particular, compared with the adduct of TCNE, the product clicked with TCNQ possessed a stronger D-A conjugation and bulkier π spacers. The TCNQ product also has a larger third-order nonlinear optical property which was characterized by Z-scan experiments. This could point to potentially interesting applications of the new pyrene derivatives in optoelectronic devices and develop the new modification process for the design of different pyrene-based molecular electronic devices.