A ratiometric chemosensor for Al3+ based on naphthalene-quinoline conjugate with the resultant complex as secondary sensor for F−: Interpretation of molecular logic gates

Abstract

1-((quinolin-3-ylimino)methyl)naphthalen-2-ol (HL) has been synthesized by one step Schiff-base condensation reaction between 2-hydroxy-naphthaldehyde and 3-aminoquinoline in 1:1 ratio in acetonitrile and characterized by elemental analysis and different spectroscopic techniques. Emission spectrum of HL shows peak at 412nm with high intensity in methanol when it is excited at 350nm. In the presence of Al3+ ion, emission intensity of the Schiff-base at 412nm decreases and a new peak at 464nm emerges indicating HL as a ratiometric chemosensor for the Al3+ ion. Other metal ions are not able to change the fluorescence intensity or peak position significantly. Job’s plot analysis indicates 1:1 binding with the formation of complex (complex 1) which is supported by mass spectral measurement. Emission intensity of complex 1 at 464nm (excitation at 350nm) decreases with the gradual addition of F− ion with the concomitant development of a peak at 412nm with fast increasing intensity. Small LOD value of HL suggests it is sensitive towards Al3+. Based on change in fluorescence intensity of HL in the presence of Al3+ and F− ions at 412 and 464nm, INHIBIT and IMPLICATION molecular logic gates have been constructed and interpreted.