Contents lists available at ScienceDirect Microchemical Journal journal homepage: www.elsevier.com/locate/microc A highly selective novel multiple amide based Schif base optical chemosensor for rapid detection of Cu 2+ and its applications in real sample analysis, molecular logic gate and smart phone Amit Kumar Manna a , Meman Sahu a , Kalyani Rout a , Uttam K. Das b , Goutam K. Patra a, ⁎ a Department of Chemistry, Guru GhasidasVishwavidyalaya, Bilaspur, C.G, India b Department of Chemistry, Mahatma Gandhi Central University, Motihari, India ARTICLEINFO Keywords: Amide Schif base Colorimetric sensor Cu 2+ sensor Logic gate Smart-phone ABSTRACT A novel multiple amide based Schif base chemosensor L has been designed rationally for selective colorimetric detection of Cu 2+ ion in CH 3 OHeH 2 O (1:1 v/v, tris HCl bufer 10 µM, pH = 7.2) solution. The colour change (colourless to yellow) is so prominent to be visible in bare eye. From the absorption titration, job's plot mea- surement and ESI-MS revealed that receptor-analyte binding occurs in a 2:1 fashion and the binding sites were confrmed by the X-ray single crystal structure of host-guest complex. Solvent dependent crystal structure from a homoleptic monomer to 2D polymer was observed. The detection limit was found to be 1.8 µM with the asso- ciationconstantvalue1.3×10 2 M −1/2 whichishighlydesirablefor2:1complexes.ThechemosensorLhasbeen applied for construction of binary logical device, recovery of contaminated water samples and smart-phone based analysis. 1. Introduction Sensing of less biodegradable heavy metal ions like Hg 2+ , Cu 2+ , Ni 2+ ,Pb 2+ andZn 2+ by efcient chemosensors is of growing interest in the feld of supra-molecular chemistry not only for the essential role of these ions, but also their toxic nature towards the environmental and biological processes [1,2]. In heavy metal series, Cu is one of the major pollutants depending on concentration, despite of being an essential constituent of several important protein and enzymes like cytochrome c-oxidase, super oxide dismutase, ceruloplasmin, tyrosinase and nu- clease [3,4]. It also helps in various biological processes e.g. formation of haemoglobin and iron utilisation in the body [5,6]. Thus it can be considered as 3rd most essential trace element after Fe and Zn in bio- logical system. However the existence of unregulated Cu 2+ ion in the body causes toxicity due the formation of harmful reactive oxygen species. As a result, major syndromes like Parkinson's disease, Wilson's disease, Meknes syndrome, Alzheimer's disease and central nervous system disorder take place, which causes liver and kidney damage [7–13]. Although several conventional techniques like chromatography [14], inductively coupled plasma mass spectroscopy (ICPMS) [15], atomic absorption spectroscopy (AAS) [16], inductively coupled plasma emission spectroscopy (ICP-ES) [17] and several other methods [18–20] are available to detect and quantify Cu 2+ ions, but most of them are associated with serious drawbacks like requirement of ex- pensive and sophisticated instruments, high operating cost, careful operation procedure, skilled operator, low selectivity and time con- suming process thus these methods are inadaptable for on-site de- termination [21]. Due to operational simplicity, easy visualisation, high selectivity and short time response optical sensor has much more at- traction in current feld of research in sensing technology. Since during the last two decades, Schif base organic frameworks have been extensively used in optical sensing due to their suitable geometrical and electronic arrangements, thus improve selectivity as well as sensitivity. The ligand metal charge transfer (LMCT) and in- tramolecular charge transfer (ICT) has crucial role for colorimetric sensing. Amongst the optical methods, colorimetric sensing is especially attractive due to its simplicity, real time analysis and cost efective in comparison to fuorometric sensing, where more sophisticated instru- ments and UV radiation source are used [22].AlsoforCu 2+ ion, due to its paramagnetic nature quenching process predominates in the host- guest complex which makes difcult to fuorometric analysis. Although somepreviousreportbasedoncolorimetricSchifbasechemosensorare available, but thorough characterisation as well as isolation of host- guest complex in the form of single crystal is still scanty in the litera- ture. As a part of our ongoing research [23–25], herein we have https://doi.org/10.1016/j.microc.2020.104860 Received 27 February 2020; Received in revised form 21 March 2020; Accepted 21 March 2020 ⁎ Corresponding author. E-mail address: patra29in@yahoo.co.in (G.K. Patra). Microchemical Journal 157 (2020) 104860 Available online 18 April 2020 0026-265X/ © 2020 Elsevier B.V. All rights reserved. T