A smart optical probe for detection and discrimination of Zn2+, Cd2+ and Hg2+ at nano-molar level in real samples

Accepted Manuscript Title: A smart optical probe for detection and discrimination of Zn2+ , Cd2+ and Hg2+ at nano-molar level in real samples Authors: Mahuya Banerjee, Milan Ghosh, Sabysachi Ta, Jayanta Das, Debasis Das PII: DOI: Reference:

S1010-6030(19)30244-8 https://doi.org/10.1016/j.jphotochem.2019.04.002 JPC 11791

To appear in:

Journal of Photochemistry and Photobiology A: Chemistry

Received date: Revised date: Accepted date:

11 February 2019 25 March 2019 1 April 2019

Please cite this article as: Banerjee M, Ghosh M, Ta S, Das J, Das D, A smart optical probe for detection and discrimination of Zn2+ , Cd2+ and Hg2+ at nano-molar level in real samples, Journal of Photochemistry and amp; Photobiology, A: Chemistry (2019), https://doi.org/10.1016/j.jphotochem.2019.04.002 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

A smart optical probe for detection and discrimination of Zn2+, Cd2+ and Hg2+ at nano-molar level in real samples

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Mahuya Banerjee, Milan Ghosh, Sabysachi Ta, Jayanta Das and Debasis Das*

Department of Chemistry, The University of Burdwan, Burdwan, 713104, West Bengal, India. E-mail address: [email protected] (D Das)

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Graphical abstract

Highlights

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Report on discrimination of group 12 metal ions using a rhodamine derived smart optical probe (L). The L detects as low as 1.2 × 10−9 M Zn2+, 9.6×10-9 M Cd2+ and 1.5×10-10 M Hg2+. L determines Cd2+ and Hg2+ in sea fishes. Binary logic gate has been constructed. TD-DFT studies support experimental spectral properties of L and its cation adduct.

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

ABSTRACT

A multi-signaling optical probe (L) having rhodamine B spacer has been developed for rapid detection and discrimination of Zn2+, Cd2+ and Hg2+ at nano-molar level. L recognizes them

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through bare eye, absorption and emission spectroscopy. The probe detects as low as 1.2 × 10−9

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M Zn2+, 9.6×10-9 M Cd2+ and 1.5×10-10 M Hg2+ with corresponding binding constants, 2.1 × 104

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M-1, 6.5 ×105 M−1 and 3.4×106 M−1 respectively. The recognition mechanism involves PET-

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CHEF-FRET processes. TD-DFT studies reveal minimum energy optimized geometries of L and

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its’ adduct with the said cations. Theoretical calculations also support experimental spectral

water samples.

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properties. Interference free new method allows determination of said cations in sea fish and

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KEYWORDS: discrimination of Zn2+, Cd2+ and Hg2+, emission, bare eye, nano-molar, logic

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gate, sea fish.

Introduction

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Development of optical probes for recognition and discrimination of group 12 elements of the modern periodic table is long standing expectations [1]. Additionally, optical imaging of biorelevant elements is an attractive method for localizing and trafficking of intracellular metal ions over other popular techniques like atomic absorption spectroscopy [2], inductively coupled plasma-mass/ atomic emission spectroscopy (ICP-MS/ AES) [3] and voltammetry [4].

Moreover, detection of multi-analyte via distinct spectral shift/ change upon interaction of the optical probe with specific analyte allows a promising and vibrant method for their trace level determination and discrimination [5]. Thus, differentiating Zn2+, Cd2+ and Hg2+ using a single

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optical probe is challenging and demanding as they possess very similar chemical properties. Zinc, one of the most bio-compatible metals [6] plays vibrant role in living species viz. gene transcription, brain activity, immune function [7], radio-protective agents [8], tumor

photosensitizers, anti-diabetic insulin mimetic [9] and anti-bacterial or anti-microbial and anticancer agents. Its disorder leads several health diseases viz. prostate tumor, delayed sexual

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maturation and incapability [10a], amyotropic lateral sclerosis (ALS), [10b-10c] Wilson’s

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diseases, [10a] age-linked macular degeneration (AMD), Alzheimer’s disease [11], cerebral

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ischemia [12], epilepsy etc. On the other hand, cadmium, listed among top twenty Hazardous

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Substances Priority List by Agency for Toxic Substances and Disease Registry and US Environmental Protection Agency (EPA) [13] is widely used in electroplating, metallurgy,

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batteries[14] etc. It has adverse effects like renal dysfunction, calcium metabolism disorders,

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reduced lung capacity, increased incidence of certain forms of cancer [15] and serious health

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disorders [15b-15h]. Thus, trace level quantification of Cd2+ from environmental and biological samples has immense importance. Finally, mercury harms kidney, lung capacity and growth of

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living systems [16]. It also damages skin, respiratory system, central nervous system and many other organs [17]. Moreover, it damages various cognitive and motor nerves to cause Minamata

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disease [18].

Noteworthy that similar property of Zn2+ and Cd2+ make it hard to differentiate them by a single probe via different optical signaling. Very few fluorescence “turn on” probes for detection and discrimination between Zn2+ and Cd2+ have limitations like extremely narrow wavelength

difference [19-20]. A simple turn on probe [20c] for recognition of both Zn2+ and Cd2+ have restrictions like narrow wavelengths difference in fluorescence spectra (emission for Zn2+, 572 nm whereas for Cd2+, 565 nm) and low exposure limit. A simple amino-terpyridine based probe

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[20d] recognizes Zn2+ and Cd2+ (λEm, 535 nm) but fails to differentiate them. Das et al.19k have reported an optical probe for Zn2+, Cd2+ and Hg2+ where Al3+ interferes. Thus, above discussion demonstrates that detection and discrimination of these three elements, using a single probe is highly demanding and time worthy.

It is to be noted that molecular arithmetic that converts chemically programmed analysis (input)

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into optical signal (output) [21] is potentially interesting research area in modern unconventional

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computing system that insisted us to build a methodical logic gate using the developed probe.

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Rhodamine derivatives have extensively been used as fluorescence probe for having unique

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properties like visible light excitation and emission, bio-compatibility, high absorption coefficient, fluorescence quantum yield [21] and analyte induced structural changes from

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colorless non-fluorescent spiro-cyclic form to open ring colored and fluorescent form [22].

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Herein, a new rhodamine B derivative has been reported that detects Zn2+, Cd2+ and Hg2+ at

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different specific wavelengths involving PET-CHEF-FRET processes [23a-23c]. The developed method has applied successfully to determine Zn2+, Cd2+ and Hg2+ in real samples [23d].

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Experimental

Materials and procedures

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High-purity buffer HEPES, rhodamine B, iso-phthalaldehyde and bis-[bis-(2-aminoethoxy)ethoxy]ethylamine are procured from Sigma−Aldrich (India). 2-Hydroxy-5-methyl-benzene-1,3dicarbaldehyde is prepared following reported process [24-25]. All required salts (nitrate and acetate) are purchased from Merck (India). The spectroscopic grade solvents are used whenever

required. Milli-Q Millipore 18.2 MΩ cm−1 water is used during the work. A Shimadzu Multi Spec 2450 UV-Vis. spectrophotometer, a Hitachi F-4500 spectro-fluorimeter and Shimadzu FTIR (IR Prestige 21 CE) spectrometer have been used for compound characterization. Mass

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spectra are recorded with QTOF 60 Micro YA 263 mass spectrometer in ES positive mode. For pH measurement, a Systronics digital pH meter (model 335) is used. 1HNMR and 13CNMR

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spectra are measured with Bruker Advance 400 (400 MHz) and 300 (75 MHz) spectrometer.

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Scheme 1 Synthetic protocols of L and R1 Synthesis of L1

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2-[2-(2-Amino-ethoxy)-ethoxy]-ethylamine (6 mL, 10.64 mmol, ρ = 1.015 g mL-1) has been added drop-wise to 30 mL ethanol solution of rhodamine B (1 g, 2.08 mmol) with constant stirring. Then the mixture is refluxed for 4 days at 600C. Finally, the solution is cooled and allowed to evaporate the solvent slowly. Next, HCl (1 mol L−1) is added until the solution

becomes clear. Then, NaOH solution (1 mol L−1) is added slowly to adjust the solution pH between 9.0–10.0. The precipitate that appeared is filtered, washed with water and dried in vacuum to afford a red solid assigned as L1. The L1 is crystallized from methanol at room

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temperature. Yield is 95.5%. Anal. calcd. (%): C, 70.98; H, 7.76 and N, 9.79. found: C, 71.32; H, 7.80 and N, 9.72. QTOF–MS ES+ (Fig.S1, ESI): [M+H]+ = 573.68. FTIR (cm−1) (Fig.S2, ESI): υ (N-H, primary amine) 3358.07, υ (C-H, aromatic) 2968.45, 2868.15 υ (C=O, carbonyl) 1670.35, υ (C=C, aromatic, symmetric) 1608.63, υ (C=N) 1512.19, υ(C-H) 1463.97, υ (C-N) 1354.03, υ (C-O, xanthan ring) 1303.88, 1222.87.

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Synthesis of L

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Mixture of 2-hydroxy-5-methylisophthalaldehyde (0.250 g, 1.25 mmol) and L1 (0.87 g,

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1.25mmol) in methanol (10 mL) is refluxed at 60oC for 6 h (Scheme 1). The reddish product

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appeared after removal of the solvent is assigned as L (1.07 g, yield: 96%). Anal. calcd (%): C, 72.61; H, 7.28 and N, 8.80; found: C, 72.63; H, 7.27 and N, 8.78. QTOF–MS ES+ (Fig.S3, ESI):

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[M+H]+ = 1274.24, 1HNMR (Fig.S4, ESI) (400 MHz, DMSO-d6), δ (ppm): 13.163 (1H, s),

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9.337 (1H, s), 8.372-8.350 (2H, s, , J = 2), 8.137-7.918 (6H, m, J = 8.8), 7.819-7.069 (10H, m, J

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= 4), 6.472-6.122 (4H, m, J = 8.8), 3.277-1.137 (23H, m, J = 7.2). 13CNMR (Fig.S5, ESI) (75 MHz, CDCl3), δ (ppm): 187.18, 177.18, 164.65, 161.18, 158.64, 147.19, 137.22, 136.38, 129.22,

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124.67, 121.10, 120.76, 117.18, 111.10, 110.40, 100.06, 40.61, 40.40, and 39.10. FTIR (cm−1) (Fig.S6, ESI): υ (O-H) 3381.21, υ (C-H, aromatic) 2968.45, 2868.15 υ (CH=N, imine bond)

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1687.71, υ (C=C, stretch) 1614.42, υ (C=O, carbonyl) 1512.19, υ (C-N, stretch) 1465.90, υ (C-O, stretch) 1375.25, 1230.58. UV-Vis. (Fig. S7a, ESI): λ (nm) in MeOH/ H2O (4/1, v/v) (ε, M−1 cm−1), 240 nm (8.5×104), 314 nm (3.84×103), 403 nm (13×102). Excitation and emission spectra (Fig.S7b and S7c, ESI, λex = 366 nm, λem = 440 nm).

Synthesis of R1 A model compound (R1) is prepared by refluxing L1 (0.87 g, 1.25 mmol) with isophthalaldehyde (0.10 g, 1.25 mmol) in methanol for 6h at 600C (Scheme 1). After removal of the

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solvent, the obtained compound is assigned as R1 (1.015 g, yield, 95%). Anal. calcd (%): C, 73.54; H, 7.37 and N, 9.01. found: C, 73.48; H, 7.39 and N, 8.93. 1HNMR (Fig.S8, ESI) (400

MHz, DMSO-d6), δ (ppm): 8.546 (1H, s), 7.828-7.674 (7H, m, , J = 2), 7.497-7.191 (14H, m, J = 11.2), 7.047-6.028 (4H, m, J = 8), 3.370-1.060 (23H, m). 13CNMR (Fig.S9, ESI) (75 MHz, CDCl3), δ (ppm): 178.01, 166.66, 164.41, 158.64, 142.88, 134.05, 123.08, 122.32, 121.42,

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120.84, 114.61, 111.10, 110.76, 107.42, 102.42, 88.10, 87.10, 40.88, 40.64, 39.66 and 39.52.

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QTOF–MS ES+ (Fig.S10, ESI): [M+CH3OH+H]+ = 1275.41. FTIR (cm−1) (Fig.S11, ESI): υ (C-

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H, aromatic) 2922.16, υ (CH=N, imine bond) 1687.71, υ (C=C, stretch) 1614.42, υ (C=O,

Synthesis of [L -Zn2+] adduct

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carbonyl) 1546.91, υ (C-N, stretch) 1413.82, υ (C-O, stretch) 1018.41.

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Methanol solution of L (2.01 g, 4.73 mmol, 10 mL) is added drop-wise to aqueous solution of

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Zn(NO3)2.6H2O (0.3 g, 4.73 mmol, 1 mL) under stirring condition and the solution is stirred for

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4h. After filtration, the filtrate is allowed for slow evaporation while brown solid appeared after 3-4 days (83%, yield). Anal. calcd. (%): C, 61.40; H, 6.46 and N, 8.16; found: C, 61.54; H, 6.49

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and N, 8.10. QTOF–MS ES+ m/z (Fig.S12, ESI), 1542.12 (89%) is assigned to C79H99N9O15Zn2 indicating 1: 2 (mole ratio) stoichiometry between L and Zn2+ and peak value at 1596.18 (48%)

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also confirmed the formation of adduct [25b] C79H99N9O15Zn2. FTIR (cm−1) (Fig.S13, ESI): υ (O-H) 3450.65, 3354.21, υ (C-H, aromatic) 2970.38, υ (C=O, carbonyl) 1664.57, υ (C=N) 1612.41, υ (C=C, aromatic) 1514.12, υ (C-N) 1116.78. UV-Vis. (Fig.S14, ESI): λ (nm) in

CH3OH/H2O (4/1, v/v) (ε, M−1 cm−1), 412 nm (3.3×104). The emission spectrum is presented in Fig.S14 (ESI). Synthesis of [L -Cd2+] adduct

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To 10 mL methanol solution of L (1.0 g, 0.788 mmol), 1mL aqueous solution of Cd(OAC)2.4H2O (0.5 g, 0.788 mmol) is added drop-wise at room temperature under stirring

condition. Slow evaporation of solvent yielded light brown solid (80 %, yield). Anal. calcd. (%): C, 60.41; H, 6.34 and N, 7.05; found: C, 60.54; H, 6.49 and N, 6.99. The QTOF–MS ES+

(Fig.S15, ESI) at m/z, 1615.43 (95%) indicates 1: 2 (mole ratio) stoichiometry25b between L and

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Cd2+ whereas formation a peak at 1679.44 (32%) also presents L-Cd2+ adduct. FTIR (cm−1) Fig.

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S16, ESI: υ (C-H) 2941.44, υ (C=O, carbonyl) 1546.91, υ (C-O) 1413.82. UV-Vis. (Fig. S17,

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ESI): λ (nm) in MeOH/H2O, 4/1, v/v (ε, M−1 cm−1): 315 nm (6.2×103). Emission spectrum is

Synthesis of [L -Hg2+] adduct

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presented in Fig. S17 (ESI).

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To aqueous solution of Hg(NO3)2·6H2O (0.17 g, 0.524 mmol,1 mL), methanol solution of L

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(0.668 g, 0.0524 mmol, 10 mL) is added drop-wise under stirring condition for 2h. Slow

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evaporation of the solvent yielded blood red precipitate (Yield 89%). Anal. calcd. (%): C, 57.80; H, 6.31; Hg, 12.07 and N, 8.43; found: C, 57.79; H, 6.35 and N, 8.48. QTOF-MS ES+ (Fig. S18,

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ESI) at m/z, 1671.61 (92%) indicates 1:1 (mole ratio) stoichiometry between L and Hg2+. FTIR (cm−1) (Fig. S19, ESI): υ (C-H, stretch) 2926.01, υ (C=O, carbonyl) 1616.35, υ (C=C, aromatic)

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1521.84, υ (C-O, xanthan ring) 1381.03. UV-Vis. (Fig. S20, ESI): λ (nm) in MeOH/H2O, 4/1, v/v (ε, M−1 cm−1): 560 nm (1.02×106), 424 nm (4.76×103). Emission spectrum is presented in Fig. S20 (ESI). Results and discussion

L has weak emission at 440 nm (λex, 366 nm) in HEPES-buffered aqueous methanol (MeOH/ H2O, 4/1, v/v, pH 7.4), attributed to the emission from 2-hydroxy-5-methyl-benzene-1, 3-diimine unit to rhodamine unit (Fig. S7, ESI). In presence of Zn2+, Cd2+ and Hg2+, it emits deep red for

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Hg2+, green for Zn2+ and blue for Cd2+ upon UV light irradiation (Fig. 1). Interestingly, Hg2+ shows intense pink in bare eye (Fig. 1). The steady state emission spectrum of L is perturbed in presence of nano-molar Zn2+, Cd2+ and Hg2+ while other common cations viz. Na+, K+, Mg2+,

Ca2+, Al3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Ag+, Pd2+, Fe2+, Cr6+ and mix (Fig. 2, Fig. S21,

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ESI) remain silent (λex, 366 nm).

Fig. 1 Change of color of L under normal and UV light after addition of Zn2+, Cd2+ and Hg2+ in HEPES-buffered

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aqueous methanol (20 mM, MeOH/ H2O, 4/1, v/v, pH 7.4)

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The pH of the medium is optimized for best performance of the probe. Hence, Zn2+, Cd2+ and

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Hg2+ are mixed with L separately in different sets and adjusted different pH (pH 3.0 -12.0). Significant change of emission intensities of L in absence and presence of Zn2+, Cd2+ and Hg2+

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have been observed near physiological pH, 7.4 (Fig. S22, ESI). Hence, pH 7.4 is maintained

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through all studies using HEPES buffered aqueous methanol (20 mM, MeOH/ H2O, 4/1, v/v).

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Fig. 2 (a) Absorption and (b) emission spectra of L in presence of common metal ions (λex = 366 nm) in the mentioned media.

Among tested common cations, only Zn2+ red shifts the emission of L to bright green along with

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36 fold fluorescence enhancement (λem = 475 nm; λex = 366 nm). Though, Cd2+ enhances the

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emission of L to a little extent (Fig. S23, ESI, Fig. 3a). The quantum yield (Φ) for [L-Zn2+]

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adduct is 0.570 (λem, 475 nm, 7.12 fold enhancement). Gradual addition of Zn2+ to L enhances

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the emission intensity at 475 nm (Fig. 3b). The plot of emission intensity of L vs. [Zn2+] is shown in Fig. 3c. Absence of 581 nm emission band indicates non-interaction of rhodamine unit

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of L with Zn2+. Fig. S24 (ESI) shows 1: 2 (mole ratio) interaction between L and Zn2+, also corroborated from the mass spectrum of the [L -Zn2+] adduct (Fig. S12, ESI). Binding constant

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of L for Zn2+, determined using Hill equation is 2.1 × 104 M-1 (Fig. S25, ESI) [26]. L detects as

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low as 1.2 ×10−9 M Zn2+ (Fig. 3c, inset). UV-Vis. titration of L by Zn2+ is presented in Fig. 3d.

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Fig. 3 (a) Relative emission intensities of L in presence of common tested metal ions (λex = 366 nm, λem = 475 nm,

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red bar); (b) changes in the emission spectra of L (20 μM) with increasing [Zn2+] (0.0, 0.05, 0.1, 1.0, 2.0, 5.0, 10, 20, 30, 50, 75, 100, 200, 300, 500, 1000, 1600 and 1700 μM); (c) plot of emission intensities of L (20 μM) vs. added Zn2+ (0.05-1600 μM, blue balls); (d) changes in the absorption spectra of L (20 µM) with increasing [Zn2+] (same

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as above). Medium and pH are already mentioned above.

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Similarly, in presence of Cd2+, L shows bright blue fluorescence (λex = 366 nm). Other common metal ions remain reluctant, so far emission is concerned (Fig. 4a, Fig. S26, ESI). The emission

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intensity at 437 nm increases upon gradual addition of Cd2+ (Fig. 4b). Fluorescence titration with varying [Cd2+] (0.05 to 1700 µM) and [Cd2+] vs. emission intensity plot are shown in Fig. 4c. Absence of emission band at 581 nm clearly indicates non- interaction of rhodamine unit with Cd2+. Fig. 4c (inset) reveals that L detects as low as 9.6×10-9 M Cd2+. L interacts with Cd2+ in

1:2 (mole ratio) stoichiometry as evident from Job’s plot [27] (Fig. S27, ESI) while mass spectrum of [L -Cd2+] adduct also support this composition (Fig. S15, ESI). Cd2+ assisted blue shift of the emission band is accompanied by 31 fold fluorescence enhancement (λem, 437 nm).

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The quantum yield for [L-Cd2+] adduct is 0.408 (λem, 437 nm, Φ 5.1 fold enhancement). Binding constant of L for Cd2+ is 6.5×105 M−1 (Fig. S28, ESI) [26]. Two absorption peaks of free L, viz. 315 nm and 271 nm gradually increases with increasing [Cd2+] (Fig. 4d), indicating their interaction.

In presence of Hg2+, L strongly emits at 581 nm (λex = 366 nm) while other common tested

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cations remain reluctant (Fig. 5 (a)). Bare eye and UV light irradiated colors of L in absence and

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presence of common cations are shown in Fig. S21 (ESI). Common cations do not interfere (Fig.

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S29 and Fig S30, ESI). Addition of Hg2+ turns colorless L to deep red (Fig.1) while the emission

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intensity (λem =581 nm) gradually increases up to 71-fold in a ratiometric manner (emission intensity decreases at 438 nm) through an iso-emissive point at 468 nm (Fig. 5b). The quantum

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yield of L and its Hg2+ adduct are 0.08 and 0.851 respectively. The plot of emission intensities

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vs. [Hg2+] (λem = 581 nm) is linear up to 4 µM Hg2+ (Fig. 5c, inset) and useful for determination

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of unknown Hg2+concentration. The lowest detection limit for Hg2+ is 1.5×10-10 M. Importantly, the detection limit of L for Hg2+ is also calculated 5.6×10-10 M on the basis [26(c,d)] of 3σ/K

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formula. L binds to Hg2+ in 1:1 mole ratio, as evident from Job’s plot [27] (Fig. S31, ESI) and ESI−MS spectrum (Fig. S18, ESI) of the adduct. The binding constant of L for Hg2+ is 3.4×106

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M−1, determined from fluorescence titration using Hill equation [26] (Fig. S32, ESI). Fig.S33 (ESI) shows the ratiometric plot (F581/F438 vs. [Hg2+]). Interaction of L with Hg2+ has also been monitored by absorption spectroscopy. Two absorption peaks viz. at 424 nm and 560 nm of colorless free L gradually increases upon gradual addition of

Hg2+ while the solution turns deep pink, observed in bare eye (Fig. 5d). This suggests strong

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interaction of Hg2+ with L.

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Fig. 4 (a) Relative emission intensity of L in presence of common tested cations (λex = 366 nm, λem = 437 nm, red bar); (b) Changes in the emission spectra of L (20 μM) with increasing [Cd2+] (above mentioned concentration); (c)

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Plot of emission intensities of L (20 μM) vs. added [Cd2+] (0.05-1600 μM, blue balls); (d) Changes in the absorption spectra of L (20 µM) with added [Cd2+] (same as above).

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In presence of Hg2+, the emission maxima of L experiences red shift from 440 nm

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(characteristics of PET, from imine N-to conjugated DFP unit) to 581 nm (characteristics of rhodamine B, FRET) via an intermediate CHEF process having characteristic emission at 492

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nm. Significant overlap between emission maxima of donor unit (DFP) with the acceptor absorbance (open ring rhodamine unit) is responsible for the FRET process (Fig. S34, ESI)

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leading to strong emission at 581 nm.

Fig. 5 (a) Relative emission intensity of L in presence of common tested cations (λex = 366 nm, λem = 581 nm, red

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bar); (b) Changes in the emission spectra of L (20 μM) with increasing [Hg2+] (above mentioned concentration, λex = 366 nm); (c) Plot of emission intensities of L (20 μM) vs. added [Hg2+] (0.005-1700 μM, blue balls); (d) Changes

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in the absorption spectra of L (20 µM) with added [Hg2+] (same as above).

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The probable binding mechanism is further authenticated by control experiment using a supporting compound, R1 having lacks -OH functionality in the DFP unit. In presence of Hg2+, the emission spectrum of R1 is significantly different (Fig. S35, ESI) while the QTOF-MS spectrum support formation of the adduct (Fig. S36, ESI). Detection of an intermediate CHEF process is supported from observation of the absorption and emission spectra of R1, [R1-Zn2+]

and [R1-Cd2+] adduct (Fig. S37, ESI). The absence of absorption at 424 nm or emission at 492 nm in [R1-Hg2+] adduct establishes the necessity of –OH group of DFP for the CHEF process to occur (Fig. 5). The Hg2+ induced emission of R1 at 568 nm is ascribed to the spirolactam ring

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opening (λex, 344 nm, Fig. S35, ESI). As mentioned above, L chelates Zn2+/ Cd2+ leading to enhanced rigidity and consequently CHEF (at 475 nm/ 437 nm) is observed. Interestingly, a model compound R1, devoid of -OH group

from the DFP unit of L does not show Zn2+/Cd2+ assisted CHEF process (Fig. S37, ESI). This reveals the requirement of phenol -OH functionality for Zn2+/ Cd2+ sensing.

HNMR titration reveals the binding mode of L to Zn2+/ Cd2+. After addition of 0.5 equiv. Zn2+/

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Cd2+ to L, the alkyl protons up-field shifted from 3.26 to 3.22 ppm, indicating the connection of

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adjacent O donor to said ions. Upon addition of more Zn2+/ Cd2+ (1.0 equiv.), further downfield

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shift is observed. Moreover, the imine proton (CH=N), denoted as ‘s’ proton is downfield shifted from 9.37 ppm to 10.01 ppm (for Zn2+)/ 10.02 ppm (for Cd2+) while the ‘t’ proton disappeared

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from 13.16 ppm upon addition of 1.0 equiv. Zn2+/ Cd2+, indicating deprotonation of –OH of DFP

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moiety (Fig. S38, 39, ESI). Moreover, all aromatic ring protons have up-field shifted that

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indicates –OH unit of DFP moiety participates for Zn2+/ Cd2+ sensing. Besides, addition of 0.5 equiv. Hg2+ to L shifts alkyl protons up-field from 3.36 to 3.32 ppm,

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signifying interaction of adjacent O center with Hg2+. Upon addition of more Hg2+ (1.0 equiv.), those protons further up-field shifted to 2.58 ppm. Moreover, ring protons up-field shifted from

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6.12-8.21 ppm range to 6.00-7.95 ppm range indicating spirolactam ring opening. Fascinatingly, upon addition of 0.5 equiv. Hg2+ to L, ‘s’ proton is downfield shifted from 9.37 to 10.03 ppm due to close proximity of Hg2+ to the rhodamine B unit by Hg2+ induced folding of L. Further addition of Hg2+ (1 equiv.) shifted the ‘s’ proton more downfield. The ‘t’ proton of L remain

unchanged at 13.16 ppm upon addition of 0.5 equiv. Hg2+, indicating non-interaction of –OH donor with Hg2+ (Fig. S40, ESI). A table with all signals and their assignments is provided in Table S1 (ESI).

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A probable interaction mechanism of L with Zn2+, Cd2+ and Hg2+ is portrayed in Scheme 2. The proposed sensing mechanism (Fig. 6) is substantiated by fluorescence lifetime data. The average fluorescence lifetime of L is 0.2189 ns while the values for [L -Zn2+]/ [L -Cd2+] systems are

1.1437 and 1.4995 ns respectively. This indicates the higher stability of the metal ion adduct at excited state, supporting the CHEF process.

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After 5 min, upon addition of Hg2+ to L, the average lifetime for multi-exponential fits [28] of

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the [L -Hg2+] system measured at 492 nm (λem) increased to 0.6081 ns, accredited to the CHEF

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process (Fig. S30, ESI). Remarkably, the fluorescence life time of [L -Hg2+] system is much

M

higher, 1.6665 ns when measured at 581 nm (λem), attributed to the Hg2+ induced FRET process. The fluorescence life time decay and data fitting are shown in Fig.6 while corresponding values

D

are presented in Table S2 (ESI).

TE

A few single probes are available in literature that can detect and differentiate all the three metal

EP

ions, viz. Zn2+, Cd2+ and Hg2+. However, the most relevant and appropriate probes for each individual metal ion is compared with the present probe and presented in Table 1.

CC

Cd2+ shows greater affinity and binding constant over Zn2+ for L and hence, easily replaces Zn2+ from [L -Zn2+] complex leading to more stable [L -Cd2+] complex (Scheme 3). Thus, [L -Zn2+]

A

adduct also serve as Cd2+ sensor via displacement approach. Addition of Cd2+ to [L -Zn2+] adduct blue shifts the emission band from 475 nm to 437 nm along with fluorescence enhancement (Fig. 7).

U

SC RI PT EP

TE

D

M

A

N

Scheme 2 Proposed binding mechanism

A

CC

Fig. 6 Fluorescence life time of L and its adduct with Hg2+ (a), Zn2+ (b) and Cd2+(c)

SC RI PT U

EP

TE

D

M

A

N

Scheme 3 Facile displacement of Zn2+ by Cd2+ from [L -Zn2+] adduct

CC

Fig. 7(a) Emission intensity of L in presence of Zn2+ and mixture of Zn2+ and Cd2+ (λex = 366 nm, λem = 437 nm); (b) Absorbance of L in presence of Zn2+ and mixture of Zn2+ and Cd2+.

A

It is worth mentioning that addition of mixture of Zn2+, Cd2+ and Hg2+ to L results emission at 581 nm (Scheme 4). Addition of KI to this mixture blue shifted this emission band to that of [L Cd2+] moiety (at 437 nm) due to masking of Hg2+ by KI while KI has no effect to the emission profile of L. Further addition of Na2S shifts the emission to 475 nm (characteristics of the

emission of [L -Zn2+] adduct) by masking Cd2+. Scheme 4 shows the scope of determination and

SC RI PT

discrimination Zn2+, Cd2+ and Hg2+ ions individually from their mixture.

N

U

Scheme 4 Selective recognition and discrimination of Zn2+, Cd2+ and Hg2+ from their mixture by L using proper masking agents.

A

In order to have the optimized geometry of L and its Hg2+, Zn2+ and Cd2+ adduct (Fig. S41, ESI),

M

density functional theoretical (DFT) calculations have been performed using B3LYP/LanL2DZ basis set [29]. The GAUSSIAN-09 Revision C.01 program package is used for all geometries

D

design and energies findings. The geometries of all adducts in gas phase are fully optimized

TE

without restrictions of symmetry in singlet ground states for L, its adducts,

EP

[Zn2(L)(CH3O)2(H2O)(NO3)], [Cd2(L)(CH3O)3] and [Hg(L)(NO3)2(H2O)(CH3OH)] using the gradient-corrected density functional theory (DFT) level with three-parameter fit of exchange

CC

and correlation functional of Becke (B3LYP) [29]. The frontier molecular orbitals viz. HOMO and LUMO of L and adducts are shown in Fig. S42 (ESI). It is clear that Hg2+, Zn2+ and Cd2+

A

adduct are stabilized by 0.0178 eV, 0.0094 eV and 0.0151 eV respectively. In [L-Hg2+], HOMOs is existed to be majorly contained on the rodhamine moiety, while these are localized on the aldehyde moiety in the case of [L-Zn2+] and [L-Cd2+] adducts. Time-dependent Density Function Theory (TDDFT) is used for excited state connected calculations based on the optimized ground

state geometry in CPCM model. The favorable electronic energies transition calculated by TDDFT are shown as in Table S3-S6 (ESI). It is evident that metal ion adducts are stabilized over L.

SC RI PT

Discrimination between Zn2+ and Cd2+ by L allowed to construct a binary logic gate, useful in digital electronics (Fig. 8) [30]. For input, Zn2+/ Cd2+ defined as “1” state and absence of any as “0” state. The input signal X (Zn2+) and input Y (Cd2+) whereas the output signals symbolize the turn on emission at 475 nm for Zn2+ and 437 nm for Cd2+ as well as both ions. The observed

TE

D

M

A

N

U

fluorescence output either results OR gate or combination of OR and NOT gate.

Fig. 8 Truth table and logic gate illustration for instantaneous monitoring of Zn2+ and Cd2+ as input, and emission wavelength at 475 nm and at 437 nm are output.

EP

Applications in Test Strips

CC

For better understanding of the drastic change in fluorescence color of the probe L with ions (Zn2+, Cd2+, Hg2+), we have performed fluorescence imaging under test strips. At first, filter

A

paper is kept to absorb in the methanol/water (4/1) solution (5mM) of probe for 10-15 hrs. to confirm that the solution is evenly spread in paper and then the paper is dried in open air. This paper is used as test strips. After that, 5µL of each analyte (20mM) is applied in different test strips to get notable color change under UV light. Intense color change of probe with analytes are shown in Fig. 9.

SC RI PT

Fig. 9 Color change of L soaked filter paper in presence of Zn2+, Cd2+ and Hg2+ (0.1 µM) under hand held UV lamp.

The developed method is applied for analysis of Zn2+, Cd2+ and Hg2+ in real samples. To estimate the accuracy, recovery studies of the said ions have been performed at various concentration

levels and results are summarized in Tables 2-6 [24]. Details of sample analysis procedure are

U

presented in ESI. Results indicate excellent recoveries of said cations from tap water, industrial

A

N

water (collected from Asansol-Durgapur industrial zone, West Bengal, India) and zinc gluconate.

Probe type

cation

Medium

Quantu Life m yield Time (ns) 0.19 -

LOD

Reference

Naphthalimide-based

Zn2+

HEPES (50 mM,100 mM KNO3, 1% DMSO, pH 7.2)

57 nM

Chem. Commun. 2013, 49, 11430

Ratiometric, ICT

Zn2+

CH3CN/ H2O, 9/1, v/v)

1.2× 108

-

-

10 µM

EtOH

-

-

-

1.7 × 10−5 M

Chem.Commun. 2012, 48, 1039 Chem. Commun, 2011, 47, 5798 Chem. Commun, 2012, 48, 4764

Off-On type

Zn2+ Zn2+

(DMSO : 0.5M HEPES (pH 7.4, 5 : 95)

-

-

-

-

Zn2+

DMF

-

-

-

1.1×10-7 M

Chem. Commun., 2011, 47, 5431

Ratiometric probe

Zn2+

50 mM HEPES, 100 mM KNO3, pH 7.2

-

-

-

-

Chem. Commun., 2012, 48, 8365

A

TE

D

Binding constant (M-1) 3.8× 108

EP

M

Table 1 Comparison of probes

Pyrene derivative

Zn2+

CH3CN

1.8×106

-

-

-

Chem. Commun., 2011, 47, 8796

Ratiometric probe

Zn2+

HEPES buffer (0.1 M, DMSO/H2O (9/1, v/v, 0.1 M, pH 7.4

3.9×105

-

-

3.0× 10–9 M

Dalton Trans., 2016, 45, 599

CHEF based

CC

Coumarin-derivative

Zn2+

HEPES buffered (0.1 M, EtOH/H2O, 1/1, v/v, pH 7.4)

4.1×105

-

-

2.3× 10−8 M

Dalton Trans., 2015, 44, 11797

Ratiometric probe

Zn2+

10 mM Tris–HCl, 0.1 M KNO3, 50% CH3CN, pH, 7.14)

-

-

-

0.14 µM

Dalton Trans., 2011, 40,6367

Terphenyl-phenanthroline Zn2+ based sensor

THF

3.2×1010

0.25

-

100 nM

Dalton Trans., 2012, 41, 10182

Off−On type

Zn2+

CH3CN, 0.02 M HEPES buffer medium (pH, 7.3)

2.6×105

-

Quinoline based

Zn2+

Tris-HCl (50 mM, pH 7.54), THF/H2O (9/1, v/v)

2.8× 108

Turn-On type

Zn2+

50 mM PIPES + 100 mM KCl, pH 7.0)

Benzoimidazole based ratiometric probe

Zn2+

HEPES buffer (50 mM, pH 7.2, 0.1 M KNO3, DMSO/H2O) 1/9, v/v

Turn-on fluorescence

Zn2+

50 mM PIPES, 100 mM KCl, KOH, pH 7.0

CHEF, ICT mechanism

Zn2+

CH3CN

Bis(pyrrol-2-ylmethyleneamine) based ratiomatric probe Benzothiazole based, CHEF

Zn2+

THF

Zn2+

HEPES buffer (5 mM, MeOH/H2O, 7/3, v/v, pH 7.3

“Turn on” fluorescence

Zn2+

Solid state recognition

Zn2+

SC RI PT

Ratiometric detection

-

0.252 nM

Inorg. Chem. 2014, 53, 6655

0.045

-

-

Inorg. Chem. 2010, 49, 4002

0.22

-

-

Inorg. Chem. 2010, 49, 10753

0.075

-

-

Org. Lett. 2009,11, 795

0.877

-

0.7 nM

J. Am. Chem. Soc. 2000, 122, 5644

-

0.13

5.99

-

5.0×106

0.019

-

-

New J. Chem. 2010, 34, 2176 Sens. Actuators B 2004, 99, 511

1.3×104

-

-

6.5 × 10−7 M

Sens. Actuators B, 2014, 202, 788

-

-

-

0.20 µM

Org. Biomol. Chem. 2012, 10, 8753

HEPES buffered (0.1 M, H2O/MeOH, 97.5/2.5, v/v, pH 7.4)

-

-

0.1 nM

RSC Adv. 2015,53, 3878

Zn2+

CH3CN/H2O, 1/1, v/v, pH 7.2 (at 250C)

0.124

2.03

-

J. Lumin. 2014, 146, 480

Zn2+

CH3CN/H2O (6/4; v/v, pH 7)

8.3×107

0.280

4.15

4.22 × 10-7 M Analyst, 2013, 138, 2931

‘Turn on” reversible’ probe Zn 2+

MeOH

2.2×105

-

-

3.04×10−6 M

Analyst,2012, 137,4415

“Off-On” type

Zn 2+

CHCl3

-

0.025

-

-

J. Fluoresc. 2014, 24, 13

Selective ratiometric

Zn2+

HEPES buffer, 100 % aqueous 2.2× 104 solution (0.1 M, pH 7.4) M-1/2

0.438

-

2.79×10-8 M

J. Fluoresc. 2016, 26, 87

A

‘Turn on’ fluorescence

U N

A M D

TE CH3CN

EP

CC

‘Turn-on’ fluorescence

-

Zn2+

Genetically encoded FRET Zn2+ sensors

CH3CN

2.2×104

0.33

-

-

Chem. Asian J. 2013, 8, 1441

~1 µM protein in 150 mM HEPES, 100 mM NaCl, 10% (V/V) glycerol, 1 mM dithiothreitol (pH 7.1)

-

-

-

-

Nature, 2009, 6, 737

-

4.89× 10-8

Tetrahedron Letters 2012, 53, 5848 Inorg. Chem. Commun. 2011, 14, 463 Present work

Turn-on fluorescence sensor Coumarin based Schiffbase

Zn2+

EtOH–H2O (95:5 v/v)

1.2 × 107

-

Zn2+

THF

-

-

PET-CHEF-FRET based

Zn2+

ICT based

Cd2+

‘Off-On’

Cd2+

HEPES buffer (20 mM, 2.1× 104 MeOH /H2O, 4/1, v/v, pH 7.4) Tris-HCl (0.01 M, CH3COCH3/H2O, 9/1, v/v, pH 7.4) 7.2×103 Tris-HCl (0.02 M, H2O, pH 7.5)

Excimer–monomer conversion

Cd2+

2.1×105 HEPES buffer (0.1 M, (DMSO/H2O, 4/1, v/v, pH 7.4)

Multi-Sensing,

Cd2+

HEPES buffer, pH 7.6

“Turn on” fluorescence, atiometric

Cd2+

CH3CN

PET, CHEF

Cd2+

Ratiometric probe

Cd2+

Benzothiazole based, CHEF

Cd2+

100 ppb

0.570

1.14

1.2×10−9 M

0.59

-

-

J. Am. Chem. Soc. 2007, 129, 1500

0.3

-

-

J. Am. Chem. Soc. 2008, 130, 16160

-

1.8×10-8 M

Analyst,2012, 137, 3910

-

-

4.8 nM

Anal. Chem. 2014, 86, 5999

-

-

0.12 µM, 0.34 µM

Org. Biomol. Chem. 2012, 10, 8753

HEPES buffer (0.01 M, 6.4×108 CH3CN/H2O, 9/1, pH 7.4) at 25 °C HEPES buffer EtOH/H2O (50 5.8×105 mM, 1/9, v/v, pH 7.2).

0.388

-

1.9 × 10−12 mol L−1

Chem. Commun. 2015, 51, 14227

0.60

-

1.0 × 10-7 M

J. Org. Chem. 2007, 72, 3554

HEPES buffer (5 mM, MeOH/ 1.2×104 H2O, 7/3, v/v, pH 7.3

-

-

2.1 × 10−6 M

Sens. Actuators B, 2014, 202, 788

Cd2+

6.3×103 Phosphate buffer (MeOH/H2O, 1/1, v/v, pH 7.0)

-

-

-

Indian J. Chem., 2010, 49A, 1617

BODIPY-based

Cd2+

CH3CN

0.076

-

-

Chem Asian J. 2013, 8, 1441

-

-

-

Tetrahedron Letters. 2008, 49, 3380

A

N

0.079

TE

D

M

-

EP

Naphthyridine based, PET, Cd2+ ICT

A

-

U

-

CC

Fluorescein based, PET

SC RI PT

BODIPY-based

4.4×104

.75×105 Tris– HCl buffer (0.01 MeOH/H2O, 7/3, v/v, pH 7.0)

Optical discrimination, CHEF

Cd2+

CH3CN/H2O (1/1, v/v) at 25 °C

-

0.014

-

-

Dalton Trans. 2013, 42, 14516

Naphthalimide-based

Cd2+

EtOH/H2O (1/ 10, v/v, pH 7.14)

2.4×107

-

-

5.2× 10-7 mol/L-1

Dalton Trans. 2013, 42, 1827

0.22

-

2.38 × 10-6 M Org Lett. 2009,11, 3454

Ratiometric displacement, Cd2+ CHEF, PET

Buffer solution (10 mM Tris- HCl, 0.1 M KNO3, 50%

CH3CN, pH 7.4) Cd2+

HEPES buffer (20 mM, MeOH/H2O, 4/1, v/v, pH 7.4)

6.5×105

0.408

1.49

9.6× 10-9 M

Present work

Rhodamine-based

Hg2+

CH3CN/H2O (1/1 v/v)

2.6 ×106 M-1

0.4640.659

-

0.3–0.5× 10-6 M

Org. Biomol. Chem. 2011, 9, 4467

FRET-based ratiometric

Hg2+

CH3CN-HEPES buffer, 1/1, v/v, pH , 7.12 ± 0.1)

1.5×106

-

Protein assisted fluorescence

Hg2+

AcONa buffer (50 mM, pH, 6.7)

2.4×104

-

Porphyrin-quinoline conjugate

Hg2+

HOAc–NaOAc buffer (EtOH/ H2O, 2/1, v/v, pH 6.0)

-

Rhodamine-based

Hg2+

Na2HPO4–NaH2PO4 Buffer (MeOH/H2O, 30/70, 0.2 mol L−1, pH 7.0

-

-

Pyrene based

Hg2+

H2O/DMSO (9.5/ 0.5, v/v)

1.1×105

Pentaquinone based Schiff Hg2+ Base

HEPES buffer (THF/H2O (9.5/0.5, v/v), pH 7)

-

Methionine–pyrene hybrid Hg2+ probe

HEPES buffer (MeOH/H2O, 2/1, v/v)

2 µM

Org. Biomol. Chem. 2012, 10, 8076

-

10 ppb

Org. Biomol. Chem. 2011, 9, 5051

-

2.2 × 10−8 M

Spectrochim. Acta A 2009, 72, 1084

-

9.4 nmol L−1

Chemical Papers, 2009, 63, 261

-

8.0× 10-9 M

RSC Adv. 2012, 2, 9201

0.40

-

500 ppb

Dalton Trans. 2013, 42, 15063

7.6×104

0.076

0.72

0.056 g µL−1

J. Hazard Mater, 2011, 186, 738

U

-

A

N

-

Hg2+

HEPES buffer, pH 7.6

-

-

-

10 nM

Anal. Chem. 2014, 86, 5999

Malachite green based

Hg2+

aqueous solution

-

-

-

1.7 nM

Chem. Commun., 2011, 4, 6027

Interrupted PET, TBET

Hg2+

-

2ppb

Chem. Commun., 2012, 48, 9293

Carbon nano dots based probe

Hg2+

-

-

4.2 nM

Chem Commun., 2012, 48, 1147

HEPES buffer (MeOH/H2O, 1/1, v/v pH 7.2)

(6.5 ± 0.69 0.55) ×104

10 mM Tris–HCl buffer, pH 8.5. -

EP

“Turn-on”

D

Multi-Sensing, DNA interaction

TE

M

SC RI PT

PET-CHEF-FRET

Hg2+

H2O

-

-

-

3.2 nM

Chem. Commun., 2008, 6005

Hg2+

PBS buffer (1% CH3CN, pH 7.4)

-

-

-

20 ppb

Org Lett., 2011,13, 3422

Hg2+

HEPES buffer (THF/H2O, 9.5/0.5, v/v)

7.1×104

0.54

-

2×10-6 mol L-1 Org. Lett. 2011,13, 1422

Rhodamine based

Hg2+

HEPES buffer (50 mM, EtOH/H2O, 1/1, v/v, pH 7.0)

-

0.75

-

0.91 ppb

Org Lett. 2010,12, 476

Rhodamine-Cyclen conjugate

Hg2+

CH3CN

2.3×108

-

-

-

J. Org. Chem. 2008, 73, 8571

Rhodamine-based

Hg2+

HEPES buffer (20 mM, 5.8M-2 80%(v/v, H2O/DMSO pH 7.0

0.35

-

2 ppb

Dalton Trans. 2011, 40, 6382

CC

Reactive ratiometric

A

Rhodamine based, TBET OFF-ON

FRET-based ratiometric

Hg2+

HEPES buffer (1 mM, pH 7.4, 6.73×106 2% EtOH) at 25°C

Rhodamine based

Hg2+

HEPES buffer (0.1 M, EtOH/H2O, 1/1, v/v, pH 7.4).

Ratiomatric, ICT

Hg2+

Rhodamine pyrene conjugate

2.10

4.5x 10-7 M

RSC Adv. 2014, 4, 14919

1.3×104

0.048

-

1 × 10−9 M

J. Hazar. Mater. 2013, 261, 198

CH3CN /HEPES buffer (95/5, v/v; pH 7.2)

4.95×104

0.065

-

∼2.2 × 10−7 M New J. Chem. 2011, 35, 607

Hg2+

HEPES buffer (EtOH/H2O, 1/1, v/v, pH 7.0)

1.44×106

-

-

1.9× 10-5 M

Dyes Pigments 2013, 98, 339-346

Ferrocene and TriazoleAppended Rhodamine Based

Hg2+

CH3CN/HEPES buffer (10 μM, 2/8, v/v, pH 7.3)

5.07×104

0.73 0.34

-

2.28 ppb

Organometallics 2015, 34, 1147

PET-CHEF-FRET

Hg2+

HEPES buffer (20 mM, 3.4×106 MeOH/H2O, 4/1, v/v, pH 7.4)

0.851

0.61

1.5×10-10 M

Present work

U

N

Table 2 Determination of Zn2+ in real samples (n =3)

SC RI PT

0.43

Zn2+ added (µM) Emissive intensity (a. u.) Zn2+ obtained (µM) RSD (%) Recovery (%)

tap water

15

1.5

487

12.22

1.8

499

13.99

-

D

98 96

TE

zinc gluconate

8

14.77

M

Industry water

511

A

Samples

Table 3 Determination of Cd2+ in real samples (n =3)

tap water

Cd2+ added (µM) Emissive intensity (a. u.) Cd2+ obtained (µM) RSD (%) Recovery (%)

EP

Samples

CC

Industry water

10

502

9.22

7.8

92.2

15

536

14.78

1.4

98

A

Table 4 Determination of Hg2+ in real samples (n =3) Samples

Hg2+ added (µM) Emissive intensity (a. u.) Zn2+ obtained (µM) RSD (%) Recovery (%)

tap water

12

533

11.44

4.6

95.3

Industry water

15

589

14.82

1.2

98.8

Table 5 Determination of Cd2+ in sea fish samples (n =3) Fish name

Net weight of the Cd2+ (µg/g) obtained Emissive intensity (a. u.) RSD (%) fish samples

R1

Subgenus Thunnus

1.372

0.311

152

1.7

R2

Eleutheronema tetradactylum

0.231

-

-

-

R3

Loligo duvauceli

1.229

0.125

R4

Setipinna sp.

0.269

0.088

R5

Johnieops vogleri

1.211

0.241

R6

Stolephorus indicus

0.477

0.288

146

1.7

121

1.8

135

1.5

141

1.7

U

Table 6 Determination of Hg2+ in sea fish samples (n =3)

SC RI PT

Serial No

Fish Name

Net weight of Hg2+ (µg/ g) obtained Emissive intensity (a. u.) RSD (%) the fish samples

R1

Subgenus Thunnus

1.155

R2

Eleutheronema tetradactylum

0.321

R3

Loligo duvauceli

1.211

R4

Setipinna sp

R5

Johnieops vogleri

R6

Stolephorus indicus

1.66

-

-

0.150

143

1.5

0.332

0.281

151

1.6

1.19

0.12

132

1.6

0.569

0.289

158

1.7

A

176

TE

D

M

-

EP

Conclusion

1.72

N

serial No

A rhodamine B derived smart optical probe (L) has been explored for detection and

CC

discrimination of Zn2+, Cd2+ and Hg2+ at nano-molar level in aqueous-methanol. The sensing mechanism involves PET-CHEF-FRET processes. The method being very fast and highly

A

selective, allows their bare eye visualization at physiological pH. The probe detects as low as 1.2 × 10−9 M Zn2+, 9.6×10-9 M Cd2+ and 1.5×10-10 M Hg2+ with corresponding binding constants, 2.1 × 104 M-1, 6.5 ×105 M−1 and 3.4×106 M−1 respectively. The probe shows highest selectivity for Hg2+ ion among Zn2+, Cd2+ and Hg2+. Moreover, application of the developed method for

determination of Zn2+, Cd2+ and Hg2+ in real and sea fish samples have been successful. DFT and TD-DFT studies support experimental outcome.

SC RI PT

Acknowledgement M. Ghosh and M. Banerjee are grateful to CSIR (New Delhi) and BU for fellowship. We thank

A

CC

EP

TE

D

M

A

N

U

UGC- DAE – Kolkata and UGC-CAS (II) (B. U.) for partial financial support.

Reference

[1] (a) B. Valeur, I. Leray, Design principles of fluorescent molecular sensors for cation

SC RI PT

recognition, Coord. Chem. Rev. 205 (2000) 3-40; (b) J. P. Desvergne, A. W. Czarnik, Chemosensors of Ion and Molecule Recognition NATO ASI Series, Series C:

Mathematical and Physical Sciences; Dordrecht, London, 1997; (c) J.R. Lakowicz,

Principles of Fluorescence Spectroscopy, 2nd ed., New York, 1999; (d) E. M. Goldys, Fluorescence and applications in biotechnology and life sciences; New Jersey, 2009;

U

(e) B. N. G. Giepmans, S. R. Adams, M. H. Ellisman, R.Y. Tsien, The Fluorescent

N

Toolbox for Assessing Protein Location and Function, Science, 312 (2006) 217–224;

A

(f) A. Baker, Fluorescence Excitation-Emission Matrix Characterization of Some

M

Sewage- Impacted Rivers. Environ. Sci. Technol. 35 (2001) 948–953. [2] A. Ohashi, H. Ito, C. Kanai, H. Imura; K. Ohashi, Cloud point extraction of iron(III)

D

and vanadium(V) using 8-quinolinol derivatives and Triton X-100 and determination

TE

of 10-7mol dm-3 level iron(III) in riverine water reference by a graphite furnace

EP

atomic absorption spectroscopy, Talanta, 65 (2005) 525-530. [3] H. Suyani, J. Creed, T. Davidson, J. Caruso, Inductively Coupled Plasma Mass

CC

Spectrometry And Atomic Emission Spectrometry Coupled Tohigh-Performance

A

Liquid Chromatography For Speciation And Detection Of Organotin Compounds. J. Chromatogra. Sci. 27 (1989) 139-143.

[4] (a) S. K. Srivastava, V. K. Gupta, S. Jain, PVC-Based 2,2,2-Cryptand Sensor for Zinc Ions, Anal. Chem. 68 (1996) 1272-1275. (b) R. N. Goyal, V. K. Gupta, S. Chatterjee, Voltammetric biosensors for the determination of paracetamol at carbon nanotube

modified pyrolytic graphite electrode, Sens. Actuators B. 149 (2010) 252-258. (c) V.K. Gupta, A.K. Jain, P. Kumar, PVC-based membranes of N, N′-dibenzyl1,4,10,13-tetraoxa-7,16-diazacyclooctadecane as Pb(II)-selective sensor, Sens.

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Actuators B. 120 (2006) 259–265. (d) V.K. Gupta, A. K. Jain, G. Maheshwari, H. Lang, Z. Ishtaiwi, Copper (II)-selective potentiometric sensors based on porphyrins in PVC matrix, Sens. Actuators B. 117 (2006) 99–106. (e) V. K. Gupta, L.P. Singh, R. Singh, N. Upadhyay, S. P. Kaur, B. Sethi, A novel copper (II) selective sensor based on Dimethyl 4, 4′ (o-phenylene) bis(3-thioallophanate) in PVC matrix, Journal of

U

Molecular Liquids. 174 (2012) 11–16. (f) V. K. Gupta, N. Mergu, L. K. Kumawat, A.

N

K. Singh, Selective naked-eye detection of Magnesium (II) ions using a coumarin-

A

derived fluorescent probe, Sens. Actuators B., 207 (2015) 216–223. (g) A.K. Jain,

M

V.K. Gupta, L.P. Singh, J.R. Raisoni, A comparative study of Pb2+ selective sensors based on derivatized tetrapyrazole and calix [4] arene receptors, Electrochim. Acta,

D

51 (2006) 2547–2553. (h) R. Prasad, V. K. Gupta, A. Kumar, Metallo-

TE

tetraazaporphyrin based anion sensors: regulation of sensor characteristics through

EP

central metal ion coordination, Anal. Chim. Acta. 508 (2004) 61–70. (i) S. K. Srivastava, V. K. Gupta, M. K. Dwivedi, S. Jain, Caesium PVC–crown (dibenzo-24-

CC

crown-8) based membrane sensor, Anal. Proc. 32 (1995) 21-23. (j) R.N. Goyal, V.K.

A

Gupta, N. Bachheti, Fullerene-C60-modified electrode as a sensitive voltammetric sensor for detection of nandrolone—An anabolic steroid used in doping, Anal. Chim. Acta. 597 (2007) 82–89. (k) V. K. Gupta, R. Mangla, U. Khurana, P. Kumar, Determination of Uranyl Ions Using Poly(vinyl chloride) Based 4-tertButylcalix[6]arene Membrane Sensor, Electroanalysis, 11 (1999) 573-576. (l) V.K.

Gupta, S. Jain, S. Chandra, Chemical sensor for lanthanum (III) determination using aza-crown as ionophore in poly (vinyl chloride) matrix, Anal. Chim. Acta. 486 (2003) 199–207. (m) V. K. Gupta, A. Nayak, S. Agarwal, B. Singhal, Recent Advances on

SC RI PT

Potentiometric Membrane Sensors for Pharmaceutical Analysis, Comb Chem High Throughput Screen, 14 (2011) 284-302. (n) V. K. Gupta, S. Juin, U. Khuranu, A

PVC-based pentathia-15-crown-5 membrane potentiometric sensor for mercury(II), Electroanalysis, 9 (1997) 478 -480.

[5] (a) A. Chatterjee, M. Santra, N. Won, S. Kim, J. K. Kim, S. B. Kim, K. H. Ahn,

U

Selective Fluorogenic and Chromogenic Probe for Detection of Silver Ions and Silver

N

Nanoparticles in Aqueous Media, J. Am. Chem. Soc. 131 (2009) 2040-2041. (b) W.

A

T. Mason, Fluorescent and Luminescent Probes for Biological Activity, 2nd Ed.,

M

London, 1999. (c) Y. Kawanishi, K. Kikuchi, H. Takakusa, S. Mizukami, Y. Urano, T. Higuchi, T. Nagano, Design and synthesis of intramolecular resonance-energy

D

transfer probes for use in ratiometric measurements in aqueous solution, Angew.

TE

Chem. 39 (2000) 3438-3440. (d) J. Fan, M. Hu, P. Zhan, X. Peng, Energy transfer

EP

cassettes based on organic fluorophores: construction and applications in ratiometric sensing, Chem.Soc.Rev. 42 (2013) 29-43. (e) A. P. de Silva, H. Q. N. Gunaratne,

CC

Gunnlaugsson, Huxley, A. J. M.; McCoy, C. P.; Rademacher, J. T.; Rice, T. E., T.

A

Signaling, Recognition Events with Fluorescent Sensors and Switches; Chem. Rev. 97 (1997) 1515-1566. (f) J. P. Desvergne, A. W. Czarnik, Fluorescent Chemosensors for Ion and Molecule Recognition, Kluwer Academic Publishers, Dordrecht, The Netherlands, 1997; (g) B. Valeur, I. Leray, Design principles of fluorescent molecular sensors for cation recognition, Coord. Chem. Rev. 205 (2000) 3-40. (h) A. P. de

Silva, D. B. Fox, A. J. M. Huxley, T. S. Moody, Combining luminescence, coordination and electron transfer for signallingpurposes, Coord. Chem. Rev. 205 (2000) 41-57. (i) L. Prodi, F. Bolletta, M. Montalti, N. Zaccheroni, Luminescent

SC RI PT

chemosensors for transition metal ions, Coord. Chem. Rev. 205 (2000) 59-83. (j) V. Amendola, L. Fabbrizzi, C. Mangano, P. Pallavicini, Molecular machines based on metal ion translocation, Acc. Chem. Res. 34 (2001) 488-493. (k) V. Amendola, L.

Fabbrizzi, F. Foti, M. Licchelli, C. Mangano, P. Pallavicini, A. Poggi, D. Sacchi, A. Taglietti, Light-emitting molecular devices based on transition metals, Coord. Chem.

U

Rev. 250 (2006) 273-299. (l) L. Basabe-Desmonts, D. N. Reinhoudt, M. Crego-

N

Calama, Design of fluorescent materials for chemical sensing, Chem. Soc. Rev. 36

A

(2007) 993-1017. (m) A. W. Czarnik, Chemical communication in water using

M

fluorescent chemosensors, Acc. Chem. Res. 27 (1994) 302-308. (n) X. Guo, X. Qian, L. Jia, A Highly Selective and Sensitive Fluorescent Chemosensor for Hg2+ in Neutral

D

Buffer Aqueous Solution, J. Am. Chem. Soc. 126 (2004) 2272-2273. (o) H. Zhang,

TE

L.-F. Han, K. A. Zachariasse, Y.-B. Jiang, 8-Hydroxyquinoline Benzoates as Highly

EP

Sensitive Fluorescent Chemosensors for Transition Metal Ions, Org. Lett. 7 (2005) 4217-4220. (p) X. Zhang, Y. Xiao, X. Qian, A Ratiometric Fluorescent Probe Based

CC

on FRET for Imaging Hg2+ Ions in Living Cells, Angew. Chem. 47 (2008) 8025-

A

8029.

[6] (a) B. L. Vallee, A. Galdes, The metallobiochemistry of zinc enzymes, Adv. Enzymol. Relat. Areas Mol. Biol., 56 (1984) 283−430. (b) B. L. Vallee, D. S. Auld, Zinc: biological functions and coordination motifs, Acc. Chem. Res., 26 (1993) 543−551. (c) M. Hambidge, N. Krebs, Zinc, diarrhea, and pneumonia, J. Pediatr., 135

(1999) 661−664. (d) B. L. Vallee, D. S. Auld, Zinc: biological functions and coordination motifs, Acc. Chem. Res., 1993, 26, 543-551. (e) C. J. Frederickson, S. W. Suh, D. Silva, C. J. Frederickson, R. B. Thompson, Importance of Zinc in the

SC RI PT

Central Nervous System: The Zinc-Containing Neuron, J. Nutr., 130 (2000) 1471S1483S. (f) E. L. Que, D. W. Domaille, C. J. Chang, Metals in neurobiology: probing their chemistry and biology with molecular imaging, Chem. Rev. 108 (2008) 15171549.

[7] C. Andreini, L. Banci, I. Bertini, A. Rosato, Zinc through the three domains of life, J.

U

Proteome Res., 5 (2006) 3173-3178. (b) C. Andreini, L. Banci, I. Bertini, A. Rosato,

N

Counting the zinc-proteins encoded in the human genome, J. Proteome Res., 5 (2006)

A

196-201.

M

[8] S. Emami, S. J. Hosseinimehr, S. M. Taghdisi, S. Akhlaghpoor, Kojic acid and its manganese and zinc complexes as potential radioprotective agents, Bioorg. Med.

D

Chem. Lett., 17 (2007) 45-48.

TE

[9] A. Nakayama, M. Hiromura, Y. Adachi, H. Sakurai, Molecular mechanism of

EP

antidiabetic zinc–allixin complexes: regulations of glucose utilization and lipid metabolism, J. Biol. Inorg. Chem. 13 (2008) 675-684. Z. Dai, J.W. Canary, Tailoring tripodal ligands for zinc sensing, New J. Chem. 31

CC

[10]

A

(2007) 1708-1718. (b) M. P. Cuajungco, G. J. Lees, Zinc Metabolism in the Brain: relevance to Human Neurodegenerative Disorders, Neurobiol. Dis., 4 (1997) 137– 169. (c) J. Y. Koh, S. W. Suh, B. J. Gwag, Y. Y. He, C. Y. Hsu, D. W. Choi, The role of zinc in selective neuronal death after transient global cerebral ischemia, Science, 272 (1996) 1013–1016.

[11]

(a) A. I. Bush, W. H. Pettingell, M. D. Paradis, R. E. Tanzi, The amyloid beta-

protein precursor and its mammalian homologues. Evidence for a zinc-modulated heparin-binding superfamily, J. Biol. Chem. 1994, 269, 22618-22621. (b) S.

SC RI PT

Goswami, A. K. Das, K. Aich, A. Manna, S. Maity, K. Khanra, N. Bhattacharyya, Ratiometric and absolute water-soluble fluorescent tripodal zinc sensor and its

application in killing human lung cancer cells, Analyst, 138 (2013) 4593-4598. [12]

J.Y. Koh, S. W. Suh, B. J. Gwag, Y. Y. He, C. Y. Hsu, D. W. Choi, The role of

zinc in selective neuronal death after transient global cerebral ischemia, Science, 272

(a) Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE,

N

[13]

U

(1996) 1013–1016.

A

Atlanta, GA 30341. (b) M. B. Yim, J. H. Kang, H. S. Yim, H. S. Kwak, P. B. Chock,

M

E. R. Stadtman, A gain-of-function of an amyotrophic lateral sclerosis-associated Cu, Zn-superoxide dismutase mutant: An enhancement of free radical formation due to a

D

decrease in Km for hydrogen peroxide, Proc. Natl. Acad. Sci., 93 (1996) 5709-5714.

TE

(c) J. A. Rodriguez, J. S. Valentine, D. K. Eggers, J. A. Roe, A. Tiwari, Jr. R. H.

EP

Brown,; L. J. Hayward, Familial amyotrophic lateral sclerosis-associated mutations decrease the thermal stability of distinctly metallated species of human copper/zinc

CC

superoxide dismutase, J. Biol. Chem., 277 (2002) 15932-15937. (d) C. T. Chasapis,

A

A. C. Loutsidou, C. A. Spiliopoulou, M. E. Stefanidou, Zinc and human health: an update , Arch. Toxicol., 86 (2012) 521-534.

[14]

(a) S. Satarug, M. R. Moore, Adverse health effects of chronic exposure to low-

level cadmium in foodstuffs and cigarette smoke, Environ. Health Perspect., 112 (2004) 1099-1103. (b) M. Waisberg, P. Joseph, B. Hale, Molecular and cellular

mechanisms of cadmium carcinogenesis, Toxicology, 192 (2003) 95-117. (c) R. A. Goyer, J. Liu, M. P. Waalkes, Cadmium and cancer of prostate and testis, Biometals, 17 (2004) 555-558. (a) S. Goswami, K. Aich, S. Das, A. K. Das, A. Mannaa, S. Halder, A highly

SC RI PT

[15]

selective and sensitive probe for colorimetric and fluorogenic detection of Cd2+ in aqueous media, Analyst, 138 (2013) 1903-1907. (b) United States Environmental Protectioin Agency, http:// water.epa.gov/drink; (c) World Health Organization, Avenue Appia 20, 1211 Geneva

U

27,Switzerland,http://wwwwho.int/water_sanitation_health/dwq/chemicals/cadmium/

N

en/.USA;http://www.atsdr.cdc.gov/cercla/ 07list.html. (d) G. Jiang, L. Xu, S. Song, C.

A

Zhu, Q. Wu, L. Zhang, L. Wu, Effects of long-term low-dose cadmium exposure on

M

genomic DNA methylation in human embryo lung fibroblast cells, Toxicology. 244 (2008) 49-55. (e) T. Jin, J. Lu, M. Nordberg, Toxicokinetics and biochemistry of

D

cadmium with special emphasis on the role of metallothionein, Neurotoxicology. 19

TE

(1998) 529-535. (f) S. Satarug, J. R. Baker, S. Urbenjapol, M. Haswell-Elkins, P. E.

EP

B. Reilly, D. J. Williams, M. R. Moore, A global perspective on cadmium pollution and toxicity in non-occupationally exposed population, Toxicol. Lett. 137 (2003) 65-

CC

83. (g) M. Waisberg, P. Joseph, B. Hale, D. Beyersmann, Molecular and cellular

A

mechanisms of cadmium carcinogenesis, Toxicology. 192 (2003) 95-117. (h) R. K. Zalups, S. Ahmad, Molecular handling of cadmium in transporting epithelia, Toxicol. Appl. Pharmacol. 186 (2003)163-188.

[16]

(a) P. Grandjean, P. Weihe, R. F. White, F. Debes, Cognitive Performance of

Children Prenatally Exposed to “Safe” Levels of Methylmercury, Environ. Res. 77

(1998) 165-172. (b) T. Takeuchi, N. Morikawa, H. Matsumoto, Y. Shiraishi, A pathological study of Minamata disease in Japan, Acta Neuropathol, 2 (1962) 4057.(c) H. H. Harris, I. J. Pickering, G. N. George, The Chemical Form of Mercury in

SC RI PT

Fish, Science 301 (2003) 1203. (d) Z. Zhang, D. Wu, X. Guo, X. Qian, Z. Lu, Q. Zu, Y. Yang, L. Duan, Y. He, Z. Feng, Visible Study of Mercuric Ion and Its Conjugate

in Living Cells of Mammals and Plants, Chem. Res. Toxicol. 189 (2005) 1814-1820. (e) M. Jaishankar, T. Tseten, N. Anbalagan, Mathew, B. B.; Beeregowda, K. N.,

Toxicity, mechanism and health effects of some heavy metals, Interdiscip Toxicol. 7

U

(2014) 60–72. (f) N. Pirrone, S. Cinnirella, X.R. Feng, B. Finkelman, H. R. Friedli, J.

N

Leaner, R. Mason, A. B. Mukherjee, G. B. Stracher, D. G. Streets, K. Telmer, Global

A

mercury emissions to the atmosphere from anthropogenicand natural sources, Atmos.

M

Chem. Phys. 10 (2010) 5951–5964. (g) S. Yoon, E. W. Miller, Q. He, P. H. Do, C. J. Chang, A bright and specific fluorescent sensor for mercury in water, cells, and

D

tissue, Angew. Chem Int. Ed. 46 (2007) 6658–6661. (h) S. Voutsadaki, G. K.

TE

Tsikalas, E. Klontzas, G. E. Froudakis, H. E. Katerinopoulos, A “turn-on” coumarin-

EP

based fluorescent sensor with high selectivity for mercury ions in aqueous media, Chem. Commun. 46 (2010) 3292–3294. (i) G. J. He, Y. G. Zhao, C. He, Y. Liu, C. Y.

CC

Duan, “Turn-On” fluorescent sensor for Hg2+ via displacement approach, Inorg.

A

Chem. 47 (2008) 5169–5176. (j) L. Praveen, V. B. Ganga, R. Thirumalai, T. Sreeja, M. L. P. Reddy, R. L. Varma, A new Hg2+-selective fluorescent sensor based on a 1, 3-alternate thiacalix [4] arene anchored with four 8-quinolinoloxy groups, Inorg. Chem. 46 (2007) 6277–6282.

[17]

D. W. Boening, Ecological effects, transport, and fate of mercury: a general

review, Chemosphere 40 (2000) 1335−1351. [18]

(a) C. M. L. Carvalho, E.-H. Chew, S. I. Hashemy, J. Lu, A. Holmgren, Inhibition

SC RI PT

of human thioredoxin system a molecular mechanism of mercury toxicity, J. Biol. Chem. 283 (2008) 11913-11923. (b) T. W. Clarkson, L. Magos, G. J. Myers, The

Toxicology of Mercury-Current Exposures and Clinical Menifestations, New Engl. J. Med. 2003 (349) 1731-1737. [19]

(a) X. Liu., N. Zhang, J. T. Zhou, C. Chang, D. Fang, A turn-on fluorescent

U

sensor for zinc and cadmium ions based on perylene tetracarboxylic diimide. Analyst,

N

138 (2013) 901-906. (b) H. He, K. P. Ng. Dennis, Differential Detection of Zn2+ and

A

Cd2+ Ions by BODIPY-Based Fluorescent Sensors. Chem. Asian J. 8 (2013) 1441–

M

1446. (c) D. Chao, Highly selective detection of Zn2+ and Cd2+ with a simple aminoterpyridine compound in solution and solid state. J. Chem. Sci. 128 (2016) 133–139.

D

(d) M. Li, H.-Y. Lu, R.-L. Liu, J.-D. Chen, C.-F. Chen, Turn-On Fluorescent Sensor

TE

for Selective Detection of Zn2+, Cd2+, and Hg2+ in Water. J. Org. Chem. 77 (2012)

EP

3670–3673; (e) P. G. Mahajan, D. P. Bhopate, G. B. Kolekar, S. R. Patil, N-methyl isatin nanoparticles as a novel probe for selective detection of Cd2+ ion in aqueous

CC

medium based on chelation enhance fluorescence and application to environmental

A

sample. Sens. and Actuators B. 220 (2015) 864-872; (f) S. Sarkar, T. Mondal, S. Roy, R. Saha, A. K. Ghosh, S. S. Panja, A multi-responsive thiosemicarbazone-based probe for detection and discrimination of group 12 metal ions and its application in logic gates. New J. Chem. 42 (2018) 15157-15169; (g) J. Hua, M. S. Elioff, Detection of Zn2+, Cd2+, Hg2+, and Pb2+ ions through label-free poly-Lglutamic acid. Talanta

188 (2018) 552–561; (h) M. Li, H. -Y. Lu, R. -L. Liu, J. -D. Chen, C. –F. Chen, TurnOn Fluorescent Sensor for Selective Detection of Zn2+, Cd2+, and Hg2+ in Water. J. Org. Chem. 2012, 77, 3670−3673; (i) P. G. Mahajan, N. C. Dige, B. D. Vanjare, Y.

SC RI PT

Han, S. J. Kim, S.-K. Hong, K. H. Lee, Intracellular Imaging of Zinc ion in Living cells by Fluorescein based organic nanoparticles. Sens. and Actuators B. 267 (2018) 119-128; (j) P. G. Mahajan, N. C. Dige, B. D. Vanjare, A. R. Phull, S. J. Kim, K. H. Lee, Gallotannin mediated silver colloidal nanoparticles as multifunctional Nano

platform: Rapid colorimetric and Turn-On fluorescent sensor for Hg2+, Catalytic and

U

In vitro anticancer activities. J. Lumin. 206 (2019) 624-633; (k) M. Ghosh, S. Ta, M.

N

Banerjee, M. Mahiuddin, D. Das, Exploring the Scope of Photo-Induced Electron

A

Transfer–Chelation-Enhanced Fluorescence–Fluorescence Resonance Energy

M

Transfer Processes for Recognition and Discrimination of Zn2+, Cd2+, Hg2+, and Al3+

4262–4275.

(a) M. E. McMenamin, J. Himmelfarb, T. D. Nolin, Simultaneous analysis of

TE

[20]

D

in a Ratiometric Manner: Application to Sea Fish Analysis. ACS Omega, 3 (2018)

EP

multiple aminothiols in human plasma by high performance liquid chromatography with fluorescence detection, J. Chromatogr. B: Anal. Technol. Biomed. Life Sci. 877

CC

(2009) 3274–3281. (b) C. Hwang, A. J. Sinskey, H. F. Lodish, Redox state changes in

A

density-dependent regulation of proliferation, Science, 257 (1992) 1496–1502. (c) H. He, K. P. Ng. Dennis, Differential Detection of Zn2+ and Cd2+ Ions by BODIPYBased Fluorescent Sensors. 8 (2013) 1441–1446. (d) D. Chao, Highly selective detection of Zn2+ and Cd2+ with a simple amino-terpyridine compound in solution and solid state. J. Chem. Sci. 128 (2016) 133–139.

[21]

(a) S. Adhikari, A. Ghosh, M. Ghosh, S. Guria, D. Das, Ratiometric sensing of

Fe3+ through PET-CHEF-FRET processes: Live cell imaging, speciation and DFT studies, Sens. and Actuators B 251 (2017) 942-950. (b) S. Ozlem, E. U. Akkaya,

SC RI PT

Thinking outside the silicon box: molecular and logic as an additional layer of selectivity in singlet oxygen generation for photodynamic therapy. J. Am. Chem. Soc. 131 (2009) 48-49. [22]

(a) S. Bae, J. Tae, Rhodamine-hydroxamate-based fluorescent chemosensor for

Fe (III), Tetrahedron Lett. 48 (2007) 5389–5392; (b) Y. Xiang, A. Tong, A new

U

rhodamine-based chemosensor exhibiting selective FeIII-amplified fluorescence, Org.

N

Lett. 8 (2006) 1549–1552. (c) J. L. Bricks, A. Kovalchuk, C. Trieflinger, M. Nofz, M.

A

Buschel, A. I. Tolmachev, J. Daub, K. Rurack, On the Development of Sensor

M

Molecules that Display FeIII-amplified Fluorescence, J. Am. Chem. Soc. 127 (2005) 13522–13529. (d) M. Zhang, Y. Gao, M. Li, M. Yu, F. Li, L. Li, M. Zhu, J. Zhang, T.

D

Yi, C. Huang, A selective turn-on fluorescent sensor for Fe III and application to

TE

bioimaging, Tetrahedron Lett. 48 (2007) 3709–3712. (e) Y. K. Yang, K. J. Yook, J.

EP

Tae, A rhodamine-based fluorescent and colorimetric chemodosimeter for the rapid detection of Hg2+ ions in aqueous media, J. Am. Chem. Soc. 127 (2005) 16760–

CC

16761.

A

[23]

(a) S. Goswami, K. Aich, S. Das, C. Das Mukhopadhyay, D. Sarkar, T.

K.Mondal, A new visible light excitable ICT-CHEF mediated fluorescence ‘turn on’ probe for the selective detection of Cd2+ in mixed aqueous system with live cell imaging, Dalton. Trans., 00 (2013) 1-3. (b) S. Goswami, K. Aich, D. Sen, Acridinebased Switching on Fluorescence Sensor for Cd2+ Functioning in Absolute Aqueous

Media, Chem. Lett., 41 (2012) 863-865. (c) K. Aich, S. Goswami, S. Das, C. Das Mukhopadhyay, C. K. Quah, H. K. Fun, Cd2+ triggered the fret “on”: a new molecular switch for the ratiometric detection of Cd2+ with live-cell imaging and bound X‑ ray

SC RI PT

structure, Inorg. Chem., 54 (2015) 7309−7315. (d) M. Ghosh, S. Mandal, S. Ta, D. Das, Detection and discrimination of Al3+ and Hg2+ using a single probe: Nano-level determination, human breast cancer cell (MCF7) imaging, binary logic gate

development and sea fish sample analysis, Sens. Actuators B 249 (2017) 339-347. [24]

S. Nandi, D. Das, Smart Probe for Multianalyte Signaling: Solvent Dependent

(a) D. A. Denton, H. Suschitzky, Synthetic uses of poly phosphoric acid. J.

N

[25]

U

Selective Recognition of I, ACS Sens. 1 (2016) 81−87.

A

Chem. Soc. 0 (1963) 4741-4743. (b) J. Wang, B. Liu, X. Liu, M. J. Panzner, C.

M

Wesdemiotis, Y. Pang, A binuclear Zn (II)–Zn (II) complex from a 2hydroxybenzohydrazide-derived Schiff base for selective detection of pyrophosphate,

(a) M. Ghosh, A. Ghosh, S. Ta, J. S. Matalobos, D. Das, ESIPT-Based

TE

[26]

D

Dalton Transactions 43 (2014) 14142-14146.

EP

Nanomolar Zn2+ Sensor for Human Breast Cancer Cell (MCF7) Imaging, Chemistry Select 2 (2017) 7426–7431. (b) B. Kumari, S. Lohar, M. Ghosh, S. Ta, A. Sengupta,

CC

P.P. Banerjee, A. Chattopadhyay, D. Das, Structurally Characterized Zn2+ Selective

A

Ratiometric Fluorescence Probe in 100 % Water for HeLa Cell Imaging: Experimental and Computational Studies, J. Fluoresc. 26 (2016) 87–103; (c) A. Ghorai, J. Mondal, R. Chandra, G. K. Patra, A reversible fluorescent-colorimetric imino-pyridyl bis-Schiff base sensor for expeditious detection of Al3+ and HSO3− in aqueous media. Dalton Trans. 44 (2015) 13261-13271; (d) A. Ghorai, J. Mondal, S.

Bhattacharya, G. K. Patra, A ‘chromogenic’ and ‘fluorogenic’ bis-Schiff base sensor for rapid detection of hydrazine both in solution and vapour phases. Anal. Methods 7 (2015) 10385-10393. A. Ghosh, S. Ta, M. Ghosh, S. Karmakar, A. Banik, T.K. Dangar, S. K.

SC RI PT

[27]

Mukherjee, D. Das, Dual mode ratiometric recognition of zinc acetate: nanomolar detection with in vitro tracking of endophytic bacteria in rice root tissue, Dalton Trans. 45 (2016) 599-606. [28]

(a) J. M. Bruchez, M. Moronne, P. Gin, S. Weiss, A. P. Alivisatos, Semiconductor

U

Nanocrystals as Fluorescent Biological Labels. Science, 281(1998), 2013-2016; (b)

N

W. C. W. Chan, S. Nie, Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic

A

Detection. Science, 281(1998), 2016-2018.; (c) A. Sahana, A. Banerjee, S. Lohar, B.

M

Sarkar, S. K. Mukhopadhyay. D. Das, Rhodamine-Based Fluorescent Probe for Al3+ through Time-Dependent PET–CHEF–FRET Processes and Its Cell Staining

D

Application. Inorg. Chem. 52 (2013) 3627–3633; (d) M. Ghosh, S. Ta, S. Lohar, S.

TE

Das, P. Brandão, V. Felix, D. Das. Exploring aggregation-induced emission through

EP

tuning of ligand structure for picomolar detection of pyrene, J Mol Recognit. 4 (2018) e2771.

(a) S. Adhikari, S. Mandal, A. Ghosh, P. Das, D. Das, Strategically Modified

CC

[29]

A

Rhodamine–Quinoline Conjugate as a CHEF-Assisted FRET Probe for Au3+: DFT and Living Cell Imaging Studies. J. Org. Chem. 80 (2015) 8530–8538; (b) C. Lee, W. Yang, R. G. Parr, Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. Sect. B, 37 (1988) 785-789; (c) P.J.

Hay and W.R. Wadt, Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. J. Chem. Phys., 82 (1985) 270-295. [30]

A. Ghosh, D. Das, X-ray structurally characterized sensors for ratiometric

SC RI PT

detection of Zn2+ and Al3+ in human breast cancer cells (MCF7): development of a

A

CC

EP

TE

D

M

A

N

U

binary logic gate as a molecular switch, Dalton Trans. 44 (2015) 11797-11804.