Reversible colorimetric switching of thiophene hydrazone based on complementary IMP/INH logic functions

Abstract

We have synthesized a thiophene hydrazone (receptor 1) that acts as a colorimetric receptor showing a reversible color switching (ON and OFF) function induced by anion and cation recognition. This remarkable color switching is based on two-input complementary IMP/INH logic functions. The (ON and OFF) process of this molecular switch is triggered by an anion (CH₃COO⁻, C₆H₅COO⁻, HCOO⁻, H₂PO₄⁻ or F⁻), while it is quenched by any one M^II ion of 3d (d⁵–d¹⁰) as well as Cd^II and Hg^II. A DMSO solution of receptor 1 underwent a bathochromic shift from 407 to 505 nm upon adding any one of the above-mentioned anions, while switch OFF was achieved by the addition of any one of the above-mentioned cations to regenerate a band at 407 nm.