Research paper 1,10-Phenanthroline based colorimetric and fluorescent sensor for Hg 2+ in water: Experimental and DFT study Yi-Wun Sie a , Chia-Lin Li a , Chin-Feng Wan b , Jie-Hong Chen a , Ching-Han Hu a , An-Tai Wu a,⇑ a Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan b Department of Medical Applied Chemistry, Chung Shan Medical University, Taichung City 40201, Taiwan article info Article history: Received 18 August 2017 Received in revised form 13 September 2017 Accepted 14 September 2017 Available online 21 September 2017 Keywords: Chemosensor B3LYP method Colorimetric abstract A novel colorimetric probe (L) was prepared and its metal ion sensing properties were investigated. Probe L exhibited obvious colorimetric response toward Hg 2+ in water. The association constant for probe L- Hg 2+ in water containing 0.5% DMSO (v/v) was determined as 1.77  10 5 M 1 . The detection limit of probe L for the analysis of Hg 2+ was determined as 21.72 ppb. Moreover, probe L can be used for selective sensing of Hg 2+ based on the obvious color changes in real samples. Further, the interaction between the probe L and Hg 2+ was investigated by 1 H NMR titration and the probable structure of probe L-Hg 2+ com- plex was predicted by B3LYP method. Ó 2017 Elsevier B.V. All rights reserved. 1. Introduction Mercury and its derivatives are significant environmental pollu- tants with inherent high toxicity. In the marine environment, Hg 2+ ion is converted by bacteria into toxic methylmercury, a highly potent neurotoxin, and is passed up the food chain to accumulate in humans, causing serious threat to human health [1]. Therefore, the development of simple methods for monitoring Hg 2+ in the environment and biological system is critical. Fluorescent sensors are highly selective, highly sensitive, low-cost, and suitable for real-time monitoring. Although, a large number of colorimetric and fluorescent sensors for Hg 2+ have been reported [2–10]. How- ever, there are a number of limitations in these probes, such as their complicated synthesis, low water solubility and lack of sensi- tivity. Therefore, for practical applications, a water soluble probe for the detection of Hg 2+ is still in great demands. Multidentate ligands have been widely used as a metal-binding reagent in most aspects of coordination chemistry [11–15]. Com- plexes of the 1,10-phenanthroline derivatives have been prepared https://doi.org/10.1016/j.ica.2017.09.040 0020-1693/Ó 2017 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: antai@cc.ncue.edu.tw (A.-T. Wu). Scheme 1. Synthesis of probe L. Fig. 1. UV/vis spectra of probe L (30 lM) recorded in H 2 O (0.5% DMSO) after addition of 5 equiv of various metal ions. Inorganica Chimica Acta 469 (2018) 397–401 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica