Demonstration of Multiple Logic Operations in a Heteroditopic Pyrene–Phenylimidazole–Terpyridine Conjugate Based on Optical Responses by Selective Anions and Cations: An Experimental and Theoretical Investigation

Combined experimental and density functional theory (DFT) and time-dependent density functional theory (TD-DFT) studies were carried out to investigate the structural and electronic properties of a terpyridyl-phenylimidazole system covalently linked to pyrene, 10-(4-[2,2′:6′,2″-terpyridine]­terpyridin-4′-yl-phenyl)-9H-9,11-diazacyclopenta­[e]­pyrene (tpy-HImzPy). X-ray crystal structure determination shows that the compound crystallized in monoclinic form with the space group P21/c. The anion and cation sensing properties of tpy-HImzPy were thoroughly studied in dimethyl sulfoxide and in mixed dimethyl sulfoxide–water medium through different channels such as absorption, steady-state and time-resolved emission, and 1H NMR spectroscopic methods. In this work, by grafting the pyrene moiety into the terpyridyl chelating unit, an intraligand-charge-transfer sensitive chromophore has been developed whose absorption and emission behaviors are highly sensitive to selective anions and cations, and the response profiles in terms of absorption or emission intensity and wavelength toward the tested ions varied quite a lot. On the basis of these observations, we developed a unique molecular system capable of performing multiple logic functions such as INHIBIT, OR, XOR, NOR, and XNOR by simply varying the combination and level of various ionic inputs in a systematic manner. In this work, we will also be particularly interested to see the effect of selective anion and cation on the optical properties of receptor by means of computational studies and correlate them with the experimentally observed data.