Anion and cation triggered modulation of optical properties of a pyridyl-imidazole receptor rigidly linked to pyrene and construction of INHIBIT, OR and XOR molecular logic gates: A combined experimental and DFT/TD-DFT investigation

A pyridyl-imidazole based bifunctional receptor 10-pyridin 2 yl 9H 9,11 -diaza-cyclopenta[e]pyrene (HImzPPy), wherein a pyridyl-imidazole moiety linked to 1,6-position of pyrene, has been synthesized and characterized by standard analytical and spectroscopic techniques. Unambiguous structure of the compound in the solid state was determined by single crystal X-ray crystallography. The compound was crystallized in orthorhombic system with P 21 21 21 space group. The absorption and emission properties of the receptor were modulated by selective anions and transition metal cations. Based on the response profiles in terms of absorption and emission intensity and wavelength toward Zn2+ and F- or Cd2+ and Fions, we developed a molecular system capable of mimicking the functions of INHIBIT, OR and XOR logic gates. We have also optimized the geometries of the receptor and it is imidazole NH deprotonated form (ImzPPy) and the Zn2+ complex of HImzPPy (Zn(HImzPPy)(2)](2+)) in both ground and excited states. We then proceed to compute the absorption and emission spectral behaviors of the compounds in solution using a TD-DFT approach to understand the nature of the underlying excited states involved in the transition processes. The experimentally observed shifts in the absorption and emission bands of the receptor due to the interaction with selective anions and cations are also reproduced by our calculations. (C) 2014 Elsevier B.V. All rights reserved.