Review Article Anion recognition by simple chromogenic and chromo-fluorogenic salicylidene Schiff base or reduced-Schiff base receptors Sasanka Dalapati 1 , Sankar Jana, Nikhil Guchhait ⇑ Department of Chemistry, University of Calcutta, 92, A.P.C. Road, Kolkata 700009, India highlights  Structurally simple Schiff bases or reduced Schiff bases beneficial for selective anion recognition.  Receptor and anions weak interaction studied by simple colorimetry and spectroscopy.  Cheaper and user handling anion sensing test kits for useful practical applications. graphical abstract article info Article history: Received 22 October 2013 Received in revised form 3 March 2014 Accepted 18 March 2014 Available online 2 April 2014 Keywords: Anion sensors Test kits Schiff base Reduced Schiff base Chromogenic Chromo-fluorogenic abstract This review contains extensive application of anion sensing ability of salicylidene type Schiff bases and their reduced forms having various substituents with respect to phenolic AOH group. Some of these molecular systems behave as receptor for recognition or sensing of various anions in organic or aque- ous–organic binary solvent mixture as well as in the solid supported test kits. Development of Schiff base or reduced Schiff base receptors for anion recognition event is commonly based on the theory of hydro- gen bonding interaction or deprotonation of phenolic –OH group. The process of charge transfer (CT) or inhibition of excited proton transfer (ESIPT) or followed by photo-induced electron transfer (PET) lead to naked-eye color change, UV–vis spectral change, chemical shift in the NMR spectra and fluorescence spectral modifications. In this review we have tried to discuss about the anion sensing properties of Schiff base or reduced Schiff base receptors. Ó 2014 Elsevier B.V. All rights reserved. Contents Introduction........................................................................................................... 500 Types of anion receptors................................................................................................. 500 Chromogenic anion receptors ......................................................................................... 500 Chromo-fluorogenic anion receptors ................................................................................... 504 Summary and conclusions ............................................................................................... 505 http://dx.doi.org/10.1016/j.saa.2014.03.090 1386-1425/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +91 33 2350 8386; fax: +91 33 2351 9755. E-mail address: nguchhait@yahoo.com (N. Guchhait). 1 Present address: Institute for Molecular Science, National Institute of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki 444-8787, Japan. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 129 (2014) 499–508 Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa