Experimental and theoretical studies of novel hydroxynaphthalene based chemosensor, and construction of molecular logic gates

Abstract

2-Hydroxynaphthalenyl-N(4)-cyclohexyl thiosemicarbazone (CHNT) was synthesized and characterized for selective sensing of fluoride, cyanide and copper ions. The interaction between CHNT with fluoride, cyanide and copper ions have been investigated through their absorption, fluorescence and electrochemical behavior, and binding constants of corresponding ions have been calculated, which is in order of Cu2+<CN−<F−. The 1H NMR titration study strongly support the deprotonation was takes place from the N2–H8 proton which is near to the naphthalene group. The fluoride and copper sensing mechanism of CHNT has been investigated by DFT and TDDFT methods The theoretical results indicate that the proton of the N2−H in thiosemicarbazone group is captured by the added fluoride ion and then deprotonated in excited state. The excited state proton transition mechanism was further confirmed with NBO and PES analysis. The CHNT found good reversibility character with the alternative addition of Ca2+ and F−. The multi ion detection of CHNT was used to construct the NOR, XNOR and NAND molecular logic gates.