z Biological Chemistry & Chemical Biology A Single and Simple Receptor as a Multifunctional Chemosensor for the Al 3 + /Cu 2 + ions and Its Live Cell Imaging Applications. Arumugam Senthil Murugan, [a] Mohan Pandi, [b] and Jamespandi Annaraj* [a] A simple and smart chemosensor (DSA) has been developed using Schiff base ligand for highly sensitive and selective colorimetric detection of Al 3 + / Cu 2 + in partial aqueous DMSO mixture (1:1) as a solvent medium. It showed a rapid fluorescence response (~ 10 Sec) with Al 3 + as greenish yellow from weak orange fluorescence while, Cu 2 + ions affords yellow colour from fade orange colour and it can be sensed even by naked eyes. Besides showing great selectivity, the probe gives a lower sensitivity of 20 nM for Al 3 + and 0.27 mM for Cu 2 + in the fluorescence and UV-vis. spectral studies respectively. The solid state colorimetric and fluorescence changes of the probe were examined in silica supported TLC plates. The sensing mecha- nism of the proposed probe in the presence of Al 3 + and Cu 2 + was determined with the support of a job’s plot, 1 H-NMR, ESI- Mass and theoretical (DFT) analysis. Based on the observed results from the absorbance and fluorescence spectroscopic studies, a logic circuit was designed with the combination of OR, NOT and AND logic gates. Moreover, the probe DSA has been employed for live cell imaging to detect Al 3 + ions in C6 glioma cells and it showed a good cell permeability and efficiency in the detection of Al 3 + ions. Introduction The design and synthesis of chemosensor for qualitative detection of the chemical and biological species, such as Zn 2 + , Fe 3 + , Al 3 + and Cu 2 + , by a simple absorbance and fluorescence enhancement (turn-on) or quenching (turn-off) response has been received an immense attention due to their advantages of high selectivity and sensitivity even at very low concen- tration in short time. In addition, fabrication of colorimetric chemosensor for the naked-eye detection of cations has gain much more interest without the necessity of spectroscopic instrumentations. Recently, many capable colorimetric and fluorescent sensors for the detection of transition metal ions have been developed. [1–6] Aluminium is the third most predom- inant metallic element on the earth crust and its soluble ionic form (Al 3 + ) is highly toxic for the living system (human health and plants growth) at biological conditions. [7–9] Its excess deposition in brain is of high risk, can cause Parkinson’s disease, Alzheimer’s disease and dialysis encephalopathy. [10–12] Therefore, the development of fluorescent chemosensors for the detec- tion and live-cell imaging of Al 3 + is of much prominence. It also increases the acidic nature of the soil, the acidified lake soil containing higher concentration of free Al 3 + ions in the surroundings and surface water is deadly to growing plants and aquatic craniate animals. [13–19] Copper, as a trace element which holds third rank in our biological system [20] due to its excellent electrochemical behaviour, also functions as a co- catalyst in many fundamental physiological reactions in living organisms. [21–24] However, lavish of copper ions in human system is highly toxic [25] and large intake of copper could cause, high blood pressure, lethargy, etc. Many researchers have connected to the cellular toxicity of the Cu 2 + ions to consequential diseases including Alzheimer diseases, [26] Indian childhood cirrhosis [27] (liver diseases), Perkins diseases, [28] Menkes diseases [29] (copper transport disease) and Wilson diseases. [30] In the modern world, the usage of the copper is very excessive, it is used in batteries, vessels, making of alloys and electrical wires due to its good electrical conductivity and malleability, these circumstances induces more possibility to intake copper in human body than its average concentration level in blood (15.7-23.6 mM). [31] In order to detect Al 3 + or Cu 2 + ions, a number of colorimetric and fluorescent chemosensors have been reported [32–35] as excellent alternate to the conven- tional techniques. [36–44] However, most of the previously reported fluorescent chemosensors may selectively sense only one ion. Chemosensors of differential responses to dual or multiple ions are cost-effective and would be valuable in practical applications. Though, developing of such sensors with multiple ions recognition ability is a big challenging task. Generally, the research community shows much attention on the Schiff’s base receptors due to their interesting proper- ties as good fluorescent receptors for metal ions. Therefore, Schiff base derivatives integrated with fluorescent moiety are appealing tools for optical sensing of metal ions. Many of the [a] A. S. Murugan, Dr. J. Annaraj Department of Materials Science, School of Chemistry Madurai Kamaraj University Madurai-625 021, (India) E-mail: annaraj.chem@mkuuniversity.org [b] Dr. M. Pandi School of Biotechnology Madurai Kamaraj University Madurai-625 021 (India) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/slct.201601646 Full Papers DOI: 10.1002/slct.201601646 375 ChemistrySelect 2017, 2, 375 – 383 # 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim