Schiff Base Derived from 4,4'-methylenedianiline and p-anisaldehyde: Colorimetric Sensor for Cu2+, Paper Strip Sensor for Al3+ and Fluorescent Sensor for Pb2

Abstract

The condensation product (L) of 4,4'-methylenedianiline and p-anisaldehyde acts as colorimetric sensor for Cu2+ and Pb2+ ions. On interaction with Cu2+, ethanolic solution of L changes its color to brown while it becomes light pink on interaction with Pb2+. Interaction of Al3+ with L coated paper strip emits bright blue fluorescence. Metal ions like Mg2+, Cu2+, Li+, K+, Na+, Mn2+, Al3+, Hg2+, Co2+, Pb2+, Ni2+, Cd2+, Zn2+, Fe3+ do not interfere the paper strip sensor. The fluorescent intensity of L in ethanol is quenched 25 times by Pb2+ ion. The interaction between L and Pb2+ is reversible and the detection limit of Pb2+ is 10-6 M. The binding constant and stoichiometry of binding between L and Pb2+ was calculated to be 104.8 and 1:2. Theoretical calculations show that the binding of the metal ions to L are favorable and the fluorescence of L is due to π → π* transition.

Full text

ORIGINAL ARTICLE
Schiff Base Derived from 4,4′-methylenedianiline
and p-anisaldehyde: Colorimetric Sensor for Cu
2+
, Paper Strip Sensor
for Al
3+
and Fluorescent Sensor for Pb
2+
Diganta Kumar Das
1
&Satyapriya Deka
1
&Ankur Kanti Guha
2
Received: 18 July 2019 /Accepted: 10 September 2019 / Published online: 30 November 2019
#Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract
The condensation product (L)of4,4′-methylenedianiline and p-anisaldehyde acts as colorimetric sensor for Cu
2+
and Pb
2+
ions.
On interaction with Cu
2+
, ethanolic solution of Lchanges its color to brown while it becomes light pink on interaction with Pb
2+
.
Interaction of Al
3+
with Lcoated paper strip emits bright blue fluorescence. Metal ions like Mg
2+
,Cu
2+
,Li
+
,K
+
,Na
+
,Mn
2+
,
Al
3+
,Hg
2+
,Co
2+
,Pb
2+
,Ni
2+
,Cd
2+
,Zn
2+
,Fe
3+
do not interfere the paper strip sensor. The fluorescent intensity of Lin ethanol is
quenched 25 times by Pb
2+
ion. The interaction between Land Pb
2+
is reversible and the detection limit of Pb
2+
is 10
−6
M. The
binding constant and stoichiometry of binding between Land Pb
2+
was calculated to be 10
4.8
and 1:2. Theoretical calculations
show that the binding of the metal ions to Lare favorable and the fluorescence of Lis due to π→π*transition.
Keywords 4,4′-methylenedianiline .P-anisaldehyde .Fluorescence .Sensor .Paper strip .Gaussian
Introduction
Naked eye sensing of hazardous metal ions in water is gaining
importance because of its applicability among common peo-
ple. Colorimetry (change in color) [1] and fluorescence
(change in color under UV lamp) [2–5] are two methods use-
ful for naked eye sensing. Compared to solution, paper strips
[6] are more efficient for naked eye detection of an analyte.
Development of new colorimetric and fluorescent sensors for
lead (Pb
2+
) is of great demand because even in very low con-
centration Pb
2+
may cause serious health issues [7].
Neurological, cardiovascular, and developmental disorders
can be linked to the exposure to Pb
2+
even at nano level [8,
9]. Children may undergo mental retardation due to Pb
2+
tox-
icity [10].ThereasonbehindtoxicityofPb
2+
is believed to be
due to its soft acidic nature, which prompts easy binding to the
sulfhydryle groups of enzymes. The common methods for
detection of Pb
2+
includes - inductively coupled plasma mass
spectroscopy [11,12], reversed phase high performance liquid
chromatography [13], anodic stripping voltametry [14], atom-
ic absorption/emission spectroscopy [15] etc. Although the
efficiency of these methods are of high order they are expen-
sive, time consuming and requires sophisticated apparatus.
Highly sensitive, easily operable, real time detectable, less
expensive fluorescence spectroscopy has received immense
interest in the detection of Pb
2+
[16–18]. Huan-Tsung Chang
et. al introduced DNAzymes for fluorescent detection of Pb
2+
ions [19]. Fluorescent sensor for Pb
2+
based on
bis(napfthalimide) derivative has been reported [20]. Au-
nanoparticles, anthracene derived chalcone, Pb
2+
stabilized
G-quadruplex have also been used for fluorescent detection
of Pb
2+
ions [21–24].
Copper ion (Cu
2+
) is involved in many biological processes
but its excess accumulation or deficiency in human body may
cause serious health issues like Wilson’s, Menken’sand
Parkinson’s disease, retardation of growth and defective ner-
vous system [25,26]. Fluorescence spectroscopy has been
used widely for sensing Cu
2+
but most of the reported sensors
are based on fluorescent quenching [27–29]. Fluorescent cop-
per sensor has been reported recently based on naphthalene
conjugate Bodipy dye [30] and coumarine derivatives [31].
Das et. al reported colorimetric sensor for Cu
2+
[32].
*Diganta Kumar Das
diganta_chem@gauhati.ac.in
1
Department of Chemistry, Gauhati University, Guwahati, Assam Pin
781014, India
2
Department of Chemistry, Cotton University, Panbazar,
Guwahati, Assam Pin 781001, India
Journal of Fluorescence (2019) 29:1467–1474
https://doi.org/10.1007/s10895-019-02443-8
Content courtesy of Springer Nature, terms of use apply. Rights reserved.