1
Rhodamine based biocompatible chemosensor for Al3+
, Cr3+
and Fe3+
ions:
extraordinary fluorescence enhancement and precursor for future
chemosensors
Ankita Roy,a Soumi Das,
a Sukriti Sacher,
b Sushil Kumar Mandal
c and Partha Roy*
,a
a Department of Chemistry, Jadavpur University, Jadavpur, Kolkata 700032, India
E-mail: [email protected]; [email protected]
b Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi 110067, India
c Department of Ecological Studies and International Centre for Ecological Engineering (ICEE),
University of Kalyani, Kalyani, Nadia 741235 West Bengal, India
Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2019
2
Fig. s1 ESI mass spectrum of (A) HL-CHO, (B) Al3+
complex of HL-CHO, (C) Cr3+
complex of
HL-CHO and (D) Fe3+
complex of HL-CHO.
3
Fig. s2 FT-IR spectrum of (A) HL-CHO, (B) Al3+
complex of HL-CHO, (C) Cr3+
complex of
HL-CHO and (D) Fe3+
complex of HL-CHO.
4
Fig. s3 13
C NMR spectrum of (A) HL-CHO in DMSO-d6 and (B) HL-CHO in the presence of
Al3+
ion in DMSO-d6.
5
Fig. s4 (A) Fluorescence intensity of HL-CHO (40 µM) at 550 nm in the presence of one
equivalent of different trivalent metal ions in 10 mM HEPES buffer in water:methanol (1:9) (pH
7.4) at room temperature; (B) Same result represented as bar diagram. Here, HL denotes HL-
CHO.
550 600 650
0
1x106
2x106
3x106
4x106
(A)
Flu
ore
sc
en
ce
In
ten
sit
y (
a.u
.)
Wavelength (nm)
HL
HL+Fe3+
HL+Cr3+
HL+Al3+
HL+In3+
HL+La3+
0
1x106
2x106
3x106
4x106
(B)
HL HL+La3+
HL+In3+
HL+Cr3+
HL+Fe3+
HL+Al3+
F.I. (a
.u.)
at
55
0 n
m
6
Fig. s5 Fluorescence intensity of HL-CHO with (A) Al3+
, (B) Cr3+
and (C) Fe3+
ions in the
presence of five equivalent of other metal ions in 10 mM HEPES buffer.4 in H2O:methanol (1:9,
v/v) (pH 7) at room temperature.
0
1x106
2x106
3x106
4x106
5x106
(B)
Mn2+
Mg2+
Zn2+
Pb2+
Cd2+
Co2+Cu
2+Hg
2+
Ni2+
Ca2+
K+
Na+
Al3+
Fe3+
Cr3+
F. I. (
a.u
.) a
t 5
50
nm
HL-CHO+Mn+
HL-CHO+Cr3+
+Mn+
0
1x106
2x106
3x106
4x106
5x106
(A)
Fe3+
Cr3+
Mn2+ Zn
2+Pb
2+Cd
2+Co
2+Cu
2+Hg
2+Ni
2+Mg
2+Ca
2+K
+Na
+Al
3+
F. I. (
a.u
.) a
t 550 n
m
HL-CHO+Mn+
HL-CHO+Al3+
+Mn+
0
1x106
2x106
3x106
4x106
5x106
(C)
Ni2+
Hg2+
Cu2+
Co2+
Cd2+
Pb2+
Zn2+
Mn2+
Mg2+Fe
3+Ca
2+K
+Na
+Cr
3+Al
3+
F. I. (
a.u
.) a
t 5
50
nm
HL-CHO+Mn+
HL-CHO+Fe3+
+Mn+
7
Fig. s6 Job’s plot analysis with (A) Al3+
, (B) Cr3+
and (C) Fe3+
ions. Analysis shows 1:1 binding
with HL-CHO. Here, L denotes HL-CHO.
0.2 0.4 0.6 0.8 1.0
0
1x106
2x106
3x106 (A)
F.I. (a
. u
.) a
t 550 n
m
CAl
3+/(CL+ C
Al3+)
0.2 0.4 0.6 0.8 1.0
0.0
8.0x105
1.6x106
2.4x106
(B)
F.I
. (a
. u
.) a
t 5
50
nm
CCr
3+/(CL+ C
Cr3+)
0.3 0.4 0.5 0.6 0.7 0.8 0.9
0.0
4.0x105
8.0x105
1.2x106
(C)
F.I. (a
. u
.) a
t 550 n
m
CFe
3+/(CL+ C
Fe3+)
8
Fig. s7 Fluorescence spectrum of HL-CHO in solid state and in solution (HEPES buffer)
550 600 650 700
0.0
2.0x104
4.0x104
6.0x104
8.0x104
1.0x105
Flu
ore
sc
en
ce
In
ten
sit
y
Wavelength (nm)
Solid state
40 M in HEPES buffer
9
Fig. s8 Non-linear plot of fluorescence intensity (at 550 nm) vs. (A) [Al3+
], (B) [Cr3+
] and (C)
[Fe3+
]
0.00 1.50x10-5
3.00x10-5
4.50x10-5
0.0
7.0x105
1.4x106
2.1x106
2.8x106
(C)
F.
I. (
a.
u.)
at
55
0 n
m
[Fe3+
] in M
0.00 1.50x10-5
3.00x10-5
4.50x10-5
0.00
1.50x106
3.00x106
4.50x106
(A)
F.I. (a
. u
.) a
t 550 n
m
[Al3+
] in M
0.00 1.50x10-5
3.00x10-5
4.50x10-5
0.0
5.0x105
1.0x106
1.5x106
2.0x106
2.5x106
(B)
F.I. (a
. u
.) a
t 550 n
m
[Cr3+
] in M
10
Fig. s9 Excited state fluorescence decay behavior of HL-CHO and its complex with Al3+
, Cr3+
and Fe3+
ions in 10 mM HEPES buffer.4 in H2O:methanol (1:9, v/v) (pH 7) at room temperature.
Here, HL denotes HL-CHO.
Determination of LOD of HL:
Limit of detection (LOD) for our probe has been determined by 3σ method by the following
equation: DL = K* Sb1/S
where K = 2 or 3 (3 in this case); here Sb1 is the standard deviation of the blank HL-CHO
solution; and S is the slope of the calibration curve obtained from Linear dynamic plot of F.I. vs
[M3+
] in M. From the calculated high LOD values, it can be concluded that HL is a very good
sensor for all the cations.
11
Fig. s10 Determination of Sb1 of the blank, HL-CHO solution.
Fig. s11 Linear dynamic plot of F.I. (at 550 nm) vs. [Al3+
] for the determination of S (slope)
0 10 20 30 40
6.0x103
8.0x103
1.0x104
1.2x104
A=5165.33333
B=159.34848
R=0.98686
SD=335.13611
Flu
ore
scen
ce In
ten
sit
y (
a.u
.)
[HL-CHO] in µM
1.0x10-5
2.0x10-5
3.0x10-5
0
1x106
2x106
3x106
4x106
A=-79322.17582
B=1.44266E11
SD=130835.39171
R=0.99462
F.
I. (
a.
u.)
at
55
0 n
m
[Al3+
] in M
12
Fig. s12 Linear dynamic plot of F.I. (at 550 nm) vs. [Cr3+
] for the determination of S (slope)
Fig. s13 Linear dynamic plot of F.I. (at 550 nm) vs. [Fe3+
] for the determination of S (slope)
0.0 1.0x10-5
2.0x10-5
3.0x10-5
4.0x10-5
0
1x106
2x106
A=10841.07018
B=6.36175E10
SD=47633.76899
R=0.99792
F. I. (
a.
u.)
at
550 n
m
[Cr3+
] in M
0.0 1.0x10-5
2.0x10-5
3.0x10-5
4.0x10-5
0
1x106
2x106
3x106
A=-201092.98596
B=7.17893E10
SD=50768.93473
R=0.99814
F.
I. (
a.
u.)
at
55
0 n
m
[Fe3+
] in M
13
Fig. s14 Fluorescence intensities of HL-CHO + M3+
(1 : 1) in the presence of Na2-EDTA for
several cycles. Fluorescence spectra monitored at 550 nm. Here, HL denotes HL-CHO.
0 1 2 3 4 5 6 7 8 9 10
0.0
2.0x106
4.0x106
(A)
HL
+A
l3++
ED
TA
HL
+A
l3++
ED
TA
HL
+A
l3++
ED
TA
HL
+A
l3++
ED
TA
HL
+A
l3+
HL
+A
l3+
HL
+A
l3+
HL
+A
l3+
HL
F. I. (
a.u
.) a
t 550 n
m
No. of Cycles
0 1 2 3 4 5 6 7 8 9 10
0
1x106
2x106
(B)
HL
+C
r3++
ED
TA
HL
+C
r3++
ED
TA
HL
+C
r3++
ED
TA
HL
+C
r3++
ED
TA
HL
+C
r3+
HL
+C
r3+
HL
+C
r3+
HL
+C
r3+
HL
F. I. (
a.u
.) a
t 5
50
nm
No. of Cycles
0 1 2 3 4 5 6 7 8 9 10
0
1x106
2x106
3x106
(C)
HL
+F
e3
++
ED
TA
HL
+F
e3
++
ED
TA
HL
+F
e3
++
ED
TA
HL
+F
e3
++
ED
TA
HL
+F
e3
+
HL
+F
e3
+
HL
+F
e3
+
HL
+F
e3
+
HL
F. I. (
a.u
.) a
t 5
50
nm
No. of Cycles
14
Table S1 Elemental analysis of HL-CHO and its complexes with Al3+
, Cr3+
and Fe3+
Species Type C H N
HL-CHO
(C37H38N4O4)
Calculated 73.73 6.35 9.30
Found 73.65 6.26 9.23
HL-CHO + Al3+
([Al(L′)NO3])
(C37H35AlN5O7)
Calculated 64.53 5.12 10.17
Found 64.42 4.93 10.12
HL-CHO + Cr3+
([Cr(L′)(H2O)]NO3)
(C37H37CrN5O8)
Calculated 60.73 5.10 9.57
Found 60.66 5.02 9.45
HL-CHO + Fe3+
([Fe(L′)(H2O)]NO3)
(C37H37FeN5O8)
Calculated 60.42 5.07 9.52
Found 60.30 4.98 9.40
0
20
40
60
80
100
120
0 1 10 50 100
% C
ell
Via
bilit
y
HL-CHO Concentrations (µM)
Fig. s15 % cell viability of human neuroblastoma SH-SY5Y cells incubated with different
concentrations (1 µM-100 µM) of HL-CHO for 12 h as determined by MTT assay. Results are
expressed as mean S.E of three independent experiments.
15
Table S2 Comparison of a few aspects of some recently published related rhodamine based chemosensors
Entry Probe Excitation (nm)/
Emission (nm)
Fluorescence Enhancement
(fold)
Concerned Cations
LOD Binding Constant (Ka) or Dissociation Constant (Kd)
Cell Imaging
Ref.
1.
500/552 98 (Al3+) 50 (Cr3+) 38 (Fe3+)
Al3+, Cr3+, Fe3+ 1.18 nM (Al3+),
1.80 nM (Cr3+),
4.04 nM (Fe3+)
Kd= 5.20±0.39 µM (Al3+) = 4.07±0.13 µM (Fe3+) = 6.49±0.21 µM (Cr3+)
No 22
2. 502/558 31 (Al3+) 26 (Cr3+) 41 (Fe3+)
Al3+, Cr3+, Fe3+ 1.34 µM (Al3+),
2.28 µM (Cr3+),
1.28 µM (Fe3+)
Ka= (1.34±0.1)×104 M−1 (Al3+) = (0.94±0.01)×104 M−1 (Fe3+) = (0.87±0.01)×104 M−1 (Cr3+)
Yes 15c
3.
330/582 (Al3+) 330/376 (Cr3+,Fe3+)
62 (Al3+) 1.7 (Cr3+) 1.47 (Fe3+)
Al3+, Cr3+, Fe3+ 1.74 nM (Al3+),
2.36 µM (Cr3+),
2.90 µM (Fe3+)
Ka= 1×104 M−1 (Al3+) = 1.2×102 M−1 (Fe3+) = 2.6×102 M−1 (Cr3+)
No 15a
4.
500/552 630 Al3+ 2.8 nM Kd = 4.88 (±0.18) µM Yes 23
5.
500/550 (Al3+) 370/454 (Zn2+)
650 (Al3+) 7 (Zn2+)
Al3+, Zn2+ 10.98 nM (Al3+)
76.92 nM (Zn2+)
Ka = 9.38×103 M−1 (Al3+) = 4.75 × 104 M−1 (Zn2+)
Yes 24
16
6.
528/552 ----- Fe3+ ----- ----- Yes 19b
7.
528/552 ----- Fe3+ ----- ----- Yes 19b
8.
528/552 ----- Fe3+ ----- ----- Yes 19b
9.
528/552 ----- Fe3+ ----- ----- Yes 19b
10.
528/552 ----- Fe3+ ----- ----- Yes 19b
O
N
NHHN
O N
HO NO2
O2N
17
11.
528/552 ----- Fe3+ ----- ----- Yes 19b
12.
510/555 14 (Al3+) 10 (Cr3+) 21 (Fe3+)
Al3+, Cr3+, Fe3 0.34 µM (Al3+),
0.31 µM (Cr3+),
0.29 µM (Fe3+)
Ka = 8.2×104 M−1 (Al3+) = 6.7×104 M-1 (Fe3+) = 6.0×104 M−1 (Cr3+)
Yes 15b
13.
525/556 18 Fe3+ 0.030 µM ----- Yes 32a
14.
500/556 ----- Hg2+ 0.5-10 µM 3.5×106 (Stability Constant) No 21
15.
525/581 ----- Hg2+ 2.5×10-8 M Ka = 2.1×107 M−1 Yes 32b
O
N
NHHN
O N
HO
NN
N
O(Et)2N N(Et)2
O
NH
ONO O
18
16.
525/581 ----- Hg2+ 4.2×10-8 M Ka = 4.4×105 M-1 Yes 32b
17.
525/581 ----- Al3+ 2.9×10-8 M Ka = 3.9×105 M-1 Yes 32b
18.
554/583 ----- Al3+, Hg2+ 1.4×10−7 M (Hg2+)
1.1×10−8 M (Al3+)
Ka = 7.0×103 M−1 (Hg2+) = 4.5×104 M−1(Al3+)
No 32c
19.
554/583 ----- Al3+, Hg2+ 1.89×10−8 M (Hg2+)
1.64×10−7 M (Al3+)
Ka = 1.49×1010 M−2 (Hg2+) = 8.0×109 M−2 (Al3+)
No 32c
20.
520/570 13 (Fe3+) 3 (Cu2+)
Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
69 µM (Cu2+)
100 µM (Fe3+)
Ka = 1.65×103 M−1 (Cu2+) = 9.75×102 M−1 (Fe3+)
No 32d
21.
570/593 ----- Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
48 nM (Cu2+) 3.9 nM (Fe3+)
Ka = 5.80×104 M−1 (Cu2+) = 6.50×104 M−1 (Fe3+)
No 32e
N
O
NH
S
N N
O
N
O
HN
S
N
N
O
NN
NN
O NN
O O
19
22.
510/572 ----- Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
18 nM (Cu2+) 33 nM (Fe3+)
Kd = 13.99×10-2 M (Cu2+) = 1.3×10-2 M (Fe3+)
Yes 32f
23.
560/578 90 (Fe3+) Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
----- ----- No 32g
24.
550/582 ----- Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
38 nM (Cu2+) 92 nM (Fe3+)
Ka = 7.1×105 M−1 (Cu2+) = 7.4×104 M−1 (Fe3+)
No 32h
25.
530/582 1098 (Fe3+) Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
6.82×10-2
µmol/L (Cu2+)
17 nmol/L (Fe3+)
Ka = 7.1×105 M−1 (Cu2+) = 7.4×104 M−1 (Fe3+)
No 32i
26.
x=9
515/572 (Cu2+) 515/580 (Fe3+)
20 (Cu2+) 14 (Fe3+)
Cu2+, Fe3+ -----
----- No 32j
27.
500/573 (Cu2+) 500/575 (Fe3+)
----- Cu2+, Fe3+ 10 nM (Cu2+)
164 nM (Fe3+)
Ka = 4.22×105 M-1 (Cu2+) = 2.94×103 M-1 (Fe3+)
No 32j
O
N
NHHN
O
N
NHO
20
28.
500/552 ----- Cu2+
(Colorimetric), Fe3+ (Fluorimetric)
250 nM (Cu2+) 90 nM (Fe3+)
Ka = 1.9×104 M-1 (Cu2+) = 1.5×105 M-1 (Fe3+)
No 32l
29. 521/586 ----- Cu2+
(Colorimetric), Hg2+ (Fluorimetric)
5.92×10-7 M (Cu2+)
2.85×10-6 M (Hg2+)
Ka = 5.38×104 M-1 (Cu2+) = 1.63×105 M-1 (Hg2+)
No 32m
30.
550/580 ----- Fe3+ 5µM Ka = 4.52×105 M-1 Yes 32n
31.
500/554 90 Hg2+ In ppb level Ka = 8.0×105±0.1 M-2 Yes 32o
32.
530/586 100 (Hg2+) Cu2+
(Colorimetric), Hg2+ (Fluorimetric)
3.37 µM (Cu2+)
150 nM (Hg2+)
Ka = 2.2×103 M-1 (Cu2+) = 1.3×104 M-1 (Hg2+)
No 32p
33.
552/582 80 (Hg2+) Cu2+ (Colorimetric), Hg2+ (Fluorimetric)
----- ----- No 32q
21
34.
450/582 259 (Hg2+) Cu2+ (Colorimetric),
Hg2+ (Fluorimetric)
1.63 µM (Cu2+)
2.36 µM (Hg2+)
Ka = 1.61×105 M-1 (Cu2+) = 3.28×105 M-1 (Hg2+)
Yes 32r
35.
520/580 132 Cu2+ 1 nM Ka = 1.36×105 M-1 Yes 32s
36.
520/582 ----- Hg2+ 0.11 µM Ka = 3.03×104 M-1 Yes 32t
37.
500/545 27 Hg2+ 26.3 nM Ka = 3.39×104 M-1 Yes 32u
38.
520/580 100 Cr3+ 7.5 nM Ka = 3.4×104 M-1 Yes 4a
39.
560/582 100 Fe3+ 0.067 µM Ka = 2.70×104 M-1 Yes 32v
40.
560/582 100 Fe3+ 0.345 µM Ka = 1.97×104 M-1 Yes 32v
N
O
N
N
O
N
O
N
N
O
22
41.
540/578 ----- Al3+ 0.16 µM Ka = 6.9×104 M-1 Yes 3e
42.
530/561 ----- Fe3+ 0.29 µM Ka = 1.4×1010 M-2 No 32w
43.
525/586 75 Hg2+ 2.1 nM Ka = 1.05×105 M-1 Yes 32x
44.
510/556 ----- Fe3+ 0.29 µM Ka = 1.17(±0.50)×104 M-1 No 32y
45
500/550 1465 (Al3+) 588 (Cr3+) 800 (Fe3+)
Al3+, Cr3+, Fe3+ 6.97 nM (Al3+),
15.80 nM (Cr3+),
14.00 nM (Fe3+)
Ka = 1.47 × 105 M-1 (Al3+) = 6.24 × 104 M-1 (Cr3+) = 8.74 × 104 M-1 (Fe3+)
Yes Present study
