2-Hydroxy-1-naphthaldehyde: A versatile building block for the development of sensors in supramolecular chemistry and molecular recognition

2-Hydroxy-1-naphthaldehyde is often used as an excellent functionalised fluorescent backbone for the synthesis of different fluorescent chemosensors. In this fluorophore, the OH moiety in 2-position acts as a hydrogen bond donor site and the aldehyde group and its derivatives in 1-position acts as hydrogen bond acceptor site. For this reason, here in this review we have presented different molecules in which the new transformations of the aldehyde group and the naphthyl-OH group create several sensors for different cations (Al3+, Zn2+, Fe3+, Hg2+, Cu2+, Na+, K+, Fe2+, Mg2+, Pb2+, Cr3+, etc), anions (AcO-, F-, CN-, PPi, I-, NO2-) as well as both cations and anions in a single platform. Furthermore the different chemodosimetric approaches for sensing different anions, toxic species (N2H4, H2S), reactive substrates (OCI-) and also the nerve agents have also been demonstrated in this review. The sensing phenomenon is based on different fluorometric pathways [ICT, ESIPT, CHEF, CHEQ, PET, CIFE, AIE] and various mechanistic pathways [NGP (Neighbouring group participation), strong hydorgen bonding interaction, C=N isomerisation, Michael addition, oxidation and reduction of different functionalities, spirocyclic ring opening, different analyte induced protection-deprotection techniques, complexation and de-complexation stategy, logic-gate, key-pad-lock etc]. The various sensing of naphthalene based different sensors has also been used in the biological assay. (C) 2017 Elsevier B.V. All rights reserved.