Synthesis, crystal structure, bovine serum albumin binding studies of 1,2,4-triazine based copper(I) complexes

Article abstract of DOI:10.1016/j.molstruc.2020.127821

A series of new copper complexes have been synthesized and completely characterized by pivotal analytical techniques. The coordination geometry around copper(I) complex was best described as distorted tetrahedral geometry. The binding of bovine serum albumin with Cu(I) complexes are also been investigated. The Stern–Volmer analysis on quenching data exhibits the presence of the static quenching mechanism. The binding constants were calculated using modified Stern-Volmer, Lineweaver–Burk and Scatchard plots. All the complexes exhibit the binding constants in the order of 10⁴. Thus, these results can contribute to the development of Cu(I) based drugs.

Full text of DOI:10.1016/j.molstruc.2020.127821

Journal of Molecular Structure 1207 (2020) 127821
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: http://www.elsevier.com/locate/molstruc
Synthesis, crystal structure, bovine serum albumin binding studies of
1,2,4-triazine based copper(I) complexes
,
,
, *
Larica Pathaw a 1, Themmila Khamrang b 1, Arunkumar Kathiravan c
,
Marappan Velusamy a
,
**
a Department of Chemistry, North Eastern Hill University, Shillong, 793 022, Meghalaya, India
b C. I. College, Bishnupur, Manipur, 795126, India
c Department of Chemistry, Vel Tech Rangarajan Dr Sagunthala R & D Institute of Science and Technology, Avadi, Chennai, 600 062, Tamil Nadu, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of new copper complexes have been synthesized and completely characterized by pivotal
analytical techniques. The coordination geometry around copper(I) complex was best described as dis-
torted tetrahedral geometry. The binding of bovine serum albumin with Cu(I) complexes are also been
investigated. The SterneVolmer analysis on quenching data exhibits the presence of the static quenching
mechanism. The binding constants were calculated using modified Stern-Volmer, LineweavereBurk and
Scatchard plots. All the complexes exhibit the binding constants in the order of 104. Thus, these results
can contribute to the development of Cu(I) based drugs.
Received 26 December 2019
Received in revised form
28 January 2020
Accepted 29 January 2020
Available online 31 January 2020
Keywords:
Copper(I)
© 2020 Elsevier B.V. All rights reserved.
Crystal structure
BSA
Fluorescence
Stern-Volmer
1. Introduction
transition metal complexes are considered. Hence, multiple copper
complexes as drugs for cancer treatment were developed, which
Copper is an indispensable micronutrient encompassed in
foundational life processes. The redox nature of copper makes
active role in biological systems and act as a key component for
many important metalloenzymes and metalloproteins [1e3]. Thus,
copper has been accepted as a controlling factor for diversity of
processes connected to cancer development and progression,
mainly in cancer growth, angiogenesis and metastasis [4,5].
Furthermore, altered copper metabolism can also comprise a
capable target for cancer therapy [6]. In this edge, quite a lot of
copper complexes containing phosphanes, imidazoles, thio-
semicarbazones and carbenes have been recognized as prospective
anticancer agents [7e11]. Since, the commercialized drugs for
cancer treatment such as cisplatin, carboplatin and metvan have
shown detrimental side effects and toxicity [12]. Hence, investi-
gation for alternative drugs has become inevitability and thus
have shown excellent anticancer activities [13]. On the other hand,
there is another decisive face in the development of drugs that is
identification of drug-protein interactions to validate the specificity
of drug action [14]. Hence, drug-protein interaction study is indeed
important.
The most abundant proteins in blood are serum albumins and
they play an imperative role in the transportation/deposition of
many drug molecules [15]. Bovine serum albumin (BSA) has been
commonly selected as the protein model due to its solubility in
water/buffer [16], extraordinary binding properties [17], and
resemblance to human serum albumin [18,19]. Investigations based
on the binding of drugs with albumins may offer useful structural
information that decides the therapeutic effect of drugs. Therefore,
the studies on the binding of drugs with BSA is of crucial and great
significance in chemistry, life sciences, and clinical medicine
[20,21]. In this paper, in order to gain insight into the binding of
metal complexes with BSA, the copper(I) complexes were consid-
ered. Since, copper is vital for the execution of different enzymes
and proteins and betrothed in respiration and DNA synthesis [22].
For these motives, we are fascinated in the development of copper
complexes. In this context, [Cu(L)(PPh3)2]NO3 have been
* Corresponding author.
** Corresponding author.
E-mail addresses: akathir23@gmail.com (A. Kathiravan), mvelusamy@gmail.com
(M. Velusamy).
1
Both authors are equally contributed.
https://doi.org/10.1016/j.molstruc.2020.127821
0022-2860/© 2020 Elsevier B.V. All rights reserved.

2
L. Pathaw et al. / Journal of Molecular Structure 1207 (2020) 127821
synthesized and its BSA affinity properties have been investigated
by UVeVis absorbance and fluorescence spectroscopic techniques.
The solution was evaporated and the solid obtained was filtered off.
The residue was washed with diethyl ether (40 mL) and dried under
vacuum. The desired products were recrystallized from DCM:hex-
ane (1:2) solvent mixture to give yellow to orange coloured
microcrystals.
2. Experimental section
2.1. Materials
[Cu(L1)(PPh3)2]NO3 (1). Yellow solid; yield: 64%; 1H NMR
(400 MHz, CDCl3)
d
8.79e8.77 (d, 1H, J ¼ 8 Hz), 8.49 (1H, s),
All the chemicals were of analytical grade and were used as
received from commercial suppliers. All the solvents were distilled
and degassed according to the standard procedures. Benzil, 4, 40-
dimethoxybenzil, acenaphthenequinone, phenanthrenequinone, 2-
cyanopyridine, hydrazine, and analytical reagents grade chemicals
and solvents were obtained commercially and used without further
purification.
8.33e8.29 (m, 1H), 7.79e7.76 (m, 1H), 7.62e7.60 (d, 2H, J ¼ 8 Hz),
7.53e7.42 (m, 9H) 7.34e7.29 (m, 6H), 7.18e7.15 (m, 23H). 13CNMR
(400 MHz, CDCl3)
129.24, 129.00, 128.91, 128.88, 125.30. 31P {1H} NMR (300 MHz,
CDCl3,
, ppm): 3.88. FT-IR [KBr, cmꢀ1]: 1639, 1512, 1367, 697. Anal.
d: 150.05, 133.16, 132.25, 130.92, 130.35, 129.97,
d
found (calcd) for C56H44CuN5O3P2: C, 70.07 (70.03); H, 4.68 (4.62);
N, 7.34 (7.29). ESI-MS (m/z): 635.10 [MeNO3ePPh3]þ.
[Cu(L2)(PPh3)2]NO3 (2). Dark orange solid; yield: 68%; 1H NMR
2.2. Methods
(400 MHz, CDCl3):
d
9.35e9.33 (d, 1H, J ¼ 8 Hz), 9.20e9.18 (d, 1H,
J ¼ 8 Hz), 9.02e9.00 (d, 1H, J ¼ 8 Hz), 8.67e8.62 (t, 2H, J ¼ 10 Hz),
8.55e8.54 (m, 1H) 8.43e8.40 (t, 1H, J ¼ 10 Hz), 8.02e7.98 (m, 2H)
7.93e7.86 (m, 2H) 7.82e7.79 (t, 1H, J ¼ 6 Hz), 7.32e7.27 (m, 6H),
FT-IR spectra were recorded by KBr pellets on a PerkinElmer
Spectrum FT-IR spectrometer (RX-1). 1H NMR spectra were recor-
ded on an FT-NMR (Bruker Avance-II 400 MHz) spectrometer by
using CDCl3 and DMSO‑d6 as solvents. Mass spectra were obtained
on a JMS-T100LC spectrometer. UVeVisible absorption and fluo-
rescence spectra of the samples were recorded in a Shimadzu UV-
1800 spectrophotometer and Hitachi make fluorescence spec-
trometer (Model: F-4500), respectively. Single crystals suitable for
X-ray diffraction were obtained by slow diffusion of hexane in to a
solution of the complex in dichloromethane. The data collection
was fulfilled using an Oxford Diffraction Xcalibur (Eos Gemini)
diffractometer at ambient temperature with graphite-
7.19e7.15 (m, 24H). 13CNMR (400 MHz, CDCl3)
d: 149.91, 145.94,
143.52, 140.01, 134.40, 134.28, 133.15, 132.56, 132.20, 130.32, 129.20,
129.10, 128.88, 127.35, 126.51, 126.27, 125.22, 124.69, 123.75, 123.57.
31P {1H} NMR (300 MHz, CDCl3, , ppm): 3.22. FT-IR [KBr, cmꢀ1]:
d
1642, 1515, 1379, 1434, 696. Anal. found (calcd) for C56H42Cu-
N5O3P2: C, 70.21 (70.18); H, 4.48 (4.42); N, 7.33 (7.31). ESI-MS (m/z):
633.18[MeNO3ePPh3]þ.
[Cu(L3)(PPh3)2]NO3 (3). Dark orange solid; yield: 73%; 1H NMR
(400 MHz, DMSO‑d6):
d
8.90e8.88 (d,1H, J ¼ 8 Hz), 8.64e8.62 (d,
1H, J ¼ 8 Hz), 8.46e8.44 (d, 1H, J ¼ 8 Hz), 8.37e8.35 (d, 1H, J ¼ 8 Hz),
monochromated Mo-K
a
radiation (
l
¼ 0.71073 Å). Data reduction
8.30e8.23 (m, 3H), 7.98e7.95 (m, 2H), 7.64e7.61 (m, 1H), 7.24 (m,
and processing were carried out using the CrysAlisPro (Agilent
Technologies Ltd, Yarnton, UK) suite of programmes. The structure
was solved by direct methods and subsequently refined by full-
matrix least squares calculations with the SHELEXL-2014 software
package [23]. All non-hydrogen atoms were refined anisotropically
while hydrogen atoms were placed in geometrically idealized po-
sitions and constrained to ride on their parent atoms. The graphics
interface package used was PLATON, and the figures were gener-
ated using the ORTEP 3.07 generation package [24].
7H), 7.14 (m, 23H). 13CNMR (400 MHz, CDCl3)
d: 150.24, 149.76,
139.67, 134.16, 133.26, 132.20, 130.22, 130.03, 129.77, 129.48, 128.82,
128.41, 127.37, 127.17, 125.20, 124.64. 31P {1H} NMR (300 MHz,
CDCl3, d
, ppm): 3.33. FT-IR [KBr, cmꢀ1]: 1637, 1518, 1384, 1434, 695.
Anal. found (calcd) for C54H40CuN5O3P2: C, 69.51 (69.56); H, 4.38
(4.32); N, 7.55 (7.51). ESI-MS (m/z): 607.21 [MeNO3ePPh3]þ.
[Cu(L4)(PPh3)2]NO3 (4). Orange solid; yield: 69%; 1H NMR
(400 MHz, CDCl3):
d
8.78e8.76 (d, 1H, J ¼ 8 Hz), 8.44 (m, 1H),
8.32e8.28 (t, 1H, J ¼ 8 Hz), 7.74e7.68 (m, 3H), 7.48e7.46 (d, 2H,
J ¼ 8 Hz), 7.33 (m, 6H), 7.17 (m, 24H), 7.00e6.94 (m, 4H), 3.93e3.90
2.3. Synthesis of ligands
(d, 6H, J ¼ 12 Hz). 13CNMR (400 MHz, CDCl3)
d: 163.11, 161.74,
156.38, 156.29, 155.81, 149.83, 149.57, 139.76, 133.18, 131.92, 130.66,
130.27, 128.84, 126.48, 126.19, 125.04, 114.53, 114.42, 55.66, 55.57.
N0-aminopyridine-2-carboximidamide and metal precursor
[Cu(PPh3)2NO3] were prepared as previously described [25,26]. The
ligands 5,6-diphenyl-3-pyridin-2-yl-[1,2,4]triazine (L1), 3-pyridin-
2-yl-phenanthro[9,10-e][1,2,4]triazine (L2), 9-pyridin-2-yl-7,8,10-
triaza-fluoranthene (L3) and 5,6-bis-(4-methoxy-phenyl)-3-
pyridin-2-yl-[1,2,4]triazine (L4) were prepared by refluxing equi-
molar ethanolic solutions containing the desired diketone and N0-
aminopyridine-2-carboximidamide for 3 h as reported elsewhere
(Scheme 1) [27].
31P{1H} NMR (300 MHz, CDCl3, , ppm): 3.00. FT-IR [KBr, cmꢀ1]:
d
1639, 1502, 1380, 1435, 695. Anal. found (calcd) for C58H48Cu-
N5O5P2: C, 68.31 (68.26); H, 4.81 (4.74); N, 6.81 (6.86). ESI-MS (m/
z): 695.26 [MeNO3ePPh3]þ.
3. Results and discussion
3.1. Synthesis and characterization of copper complexes
2.4. Synthesis of complexes
The 3-pyridin-2-yl- [1,2,4]triazine based bidentate ligands (L1-
L4) were synthesized by condensing pyridyl-2-amidrazone with
corresponding diketone in ethanol solution. The ligands were
characterized by 1H NMR spectra. Mononuclear heteroleptic cop-
per(I) complexes [Cu(N,N)(PPh3)2]NO3(1e4) have been prepared by
treating 1 equivalent of the corresponding ligand with metal pre-
cursor [Cu(PPh3)2NO3] in chloroform as solvent. The products were
isolated as nitrate salts in good yields. The complexes have been
isolated as yellow to orange coloured powders. The complexes
were stable to air and non-hygroscopic in nature and were
adequately soluble in acetonitrile, chloroform, dichloromethane,
DMF and DMSO and insoluble in water. Based on elemental anal-
ysis, 1H, 13C NMR(Figs. S1eS8)and ESI-MS (Figs. S9eS12) the
The [Cu(L)(PPh3)2]NO3 complexes 1e4 were prepared by
essentially following the same procedure and an illustrative
example is provided below for 1 (Scheme 2). Triphenylphosphine
(0.05 g, 0.2 mmol) and [Cu(PPh3)2NO3] (0.12 g, 0.2 mmol) were
suspended in CHCl3 (20 mL) and stirred at room temperature for
1 h. After complete dissolution of the triphenylphosphine, the
corresponding N,N chelating ligand (0.08 g, 0.2 mmol) dissolved in
CHCl3 (10 mL) was added dropwise to the reaction mixture. After
complete addition of the ligand, the colourless solution immedi-
ately turned yellow and then intense orange in colour and the re-
action mixture was allowed to stir at room temperature overnight.

L. Pathaw et al. / Journal of Molecular Structure 1207 (2020) 127821
3
Scheme 1. Synthesis of ligands (L1-L4).
Scheme 2. General synthesis of complexes 1e4.
complexes were formulated as [Cu(N,N)(PPh3)2]NO3, and the stoi-
chiometry of 1 is further confirmed by single crystal X-ray structure
determination. The ESI-MS data reveal that the complexes retain
their identity even in solution, which is supported by values of
molar conductivity in DMSO (LM/Uꢀ1 cm2 molꢀ1: 66e72), falling
in the range for 1:1 electrolytes. They are stable in the solid state as
well as in solution.
[30,31]. The absorption spectra of Cu(I) complexes 1e4 were
investigated in acetonitrile solutions, and the pertinent spectra are
depicted in Fig. 1. In the absorption spectra, all the complexes
exhibit intense bands in the range 370e550 nm, which probably
originates from the p/p* and n/p* transitions [32,33] located in
the bidentate ligands and triphenylphospine moieties (Fig. 1). In
addition, a low-energy broad absorption band is observed for all
the complexes, which is characteristic of metal-to-ligand charge-
The FTIR spectra of the complexes 1e4 in KBr pellets consists of
characteristics peak for
n
C]C,
n
C]N in the range of
transfer (dp(Cu) /p*(L) (MLCT) transitions.
1641e1502 cmꢀ1, the
n
NO3 vibrations for nitrate anion in all the
complexes falls in the range of 1367e1384 cmꢀ1. Peaks in the range
of 1434e1436 cmꢀ1and 695-697 cmꢀ1 in all the four complexes are
assigned to the presence of triphenylphosphine similar to those
Cu(I)-PPh3 complexes [28,29]. The 31P{1H} NMR spectra
(Figs. S13eS16) of the complexes 1-4 exhibited a signal corre-
3.2. Crystal structure of [Cu(L)(PPh3)2]NO3. (1)
Suitable crystals of complex 1 were obtained from the slow
diffusion method. The complex crystallizes in the monoclinic space
group P21/c with unit cell parameters of
a
¼
13.8524(5),
¼ 90 and
sponding to coordinated PPh3 in the range of
d 3.0e3.88 ppm
b ¼ 18.0692(7), c ¼ 19.8042(7), ¼ 90, ¼ 94.862(3),
a
b
g

4
L. Pathaw et al. / Journal of Molecular Structure 1207 (2020) 127821
Table 1
Crystallographic data and structure refinement parameters for
1.
Formula
C56H44CuN5O4P2
crystal system
space group
a (Å)
b (Å)
c (Å)
Monoclinic
P21/c
13.8524(5)
18.0692(7)
19.8042(7)
90
94.862(3)
90
4939.2(3)
4
0.559
1.313
R1 ¼ 0.0499
wR2 ¼ 0.1239
0.0817
a
b
g
(deg)
(deg)
(deg)
V (Å3)
Z
m
(mmꢀ1
)
rcalcmg/mm3
final R indices
a
R1
b
wR2
0.1428
a
R1 ¼ S||Fo| ꢀ |Fc||/S|Fo|.
b
wR2 ¼ {Sw[(F2oꢀ F2c)2]/Sw[(Fo2)2]}1/2
.
Fig. 1. Normalized absorption spectra of copper (I) complexes in acetonitrile.
binding strength between drug and albumin has significant
research. BSA is the most widely studied protein owing to its
structural homology with human serum albumin. BSA contains
amino acid residues such as tryptophan, tyrosine and phenylala-
nine. Among the residues, tryptophan exhibits superior fluores-
cence intensity than other two residues [35,36]. Most importantly,
the fluorescence of tryptophan is highly sensitive to the sur-
rounding environment. Hence, the sensitive character of trypto-
phan is extensively utilized as endogenous fluorescent probe to
understand the interaction of albumin with complexes and organic
molecules. In this esteem, fluorescence quenching is an imperative
method to study the interaction of drug with BSA.
z ¼ 4. The molecular structure of the complex with a mono cation
including the atom numbering scheme is depicted in Fig. 2. The
structure refinement details and selected bond lengths and bond
angles are listed in Tables 1 and 2 respectively. The asymmetric unit
of complex contains a complex cation, and one nitrate as the
counter ion. Copper(I) cation exhibits a distorted tetrahedral ge-
ometry by the binding of two phosphorous atoms of the PPh3
ligand and two nitrogen atoms of the bidentate ligand. The
N1eCueN2 and P1eCueP2 bond angles are 78.20(10)ꢁ, 127.91(3)ꢁ,
respectively, which are far away from the ideal value of 109.5ꢁ
indicating severe distortion around copper (I). The significant de-
viation from the ideal tetrahedral geometry is due to the restricted
bite angle of the bidentate ligands. The Cu-Npy, Cu-Ntri and CueP
distances fall within the ranges [34] expected (Cu-Npy ¼ 2.100(3)
Cu-P 2.2528 Å and Cu-Ntri 2.074(2) Å).
A solution of BSA (5
mM) was titrated with different concen-
trations of complexes (0ꢀ7
m
M) by quenching method upon
excitation at 280 nm. Fig. 3 depicts the fluorescence quenching of
BSA with 4. Other complexes (1e3) were also shows the similar
type of quenching and spectra were shown in Figs. S17aec. Fluo-
rescence intensity quenching data was then evaluated according to
SterneVolmer equation (1):
3.3. BSA-binding studies
Serum albumins are noteworthy blood proteins which have the
ability to transport the drugs. Therefore, the understanding of
I0 ¼ 1 þ KSV ½Qꢂ
(1)
=
I
where, I0 and I are the fluorescence intensities of BSA in the absence
and presence of complexes (1e4) respectively, KSV is the
SterneVolmer constant and [Q] is the concentration of the com-
plexes (1e4). SterneVolmer plots, where the intensity ratio (I0/I) is
plotted vs. the concentration of complexes are presented in Fig. 4.
As can be seen, the curves in Fig. 4 are linear which indicate the
quenching may due to dynamic process. To substantiate this
quenching process, the KSV and kq values were calculated from the
linear regressions of the SterneVolmer plots and are shown in
Table 3. Note that, the quenching rate constant (kq) can be calcu-
lated from KSV and excited state lifetime of BSA using the following
equation (2):
kq ¼ KSV
(2)
=
t0
where, t0is the fluorescence lifetime of BSA (6.05 ns) in the absence
of complexes. In general, maximum collisional quenching rate
constant (kq) in water medium is 2.0 ꢃ 1010
M
ꢀ1sꢀ1 [37]. Obviously,
the rate constant (~1012
M
ꢀ1sꢀ1) we have calculated is greater than
the limiting diffusion constant. This discrepancy in kq supports the
quenching process purely due to static.
Fig. 2. ORTEP view of complex 1, showing the atom labels and 40% of the probability of
ellipsoids. Anion and hydrogen atoms are omitted for clarity.

L. Pathaw et al. / Journal of Molecular Structure 1207 (2020) 127821
5
Table 2
Selected bond lengths (Å) and angles (ꢁ) for 1.
Bond lengths
Bond angles
Cu1eN2
Cu1eN1
Cu1eP2
Cu1eP1
2.074(2)
2.100(3)
2.2398(8)
2.2658(9)
N2eCu1eN1
N2eCu1eP2
N1eCu1eP2
N2eCu1eP1
N1eCu1eP1
P2eCu1eP1
78.20(10)
111.52(7)
116.43(7)
102.33(7)
108.24(7)
127.91(3)
Assuming, the quenching process is mainly static, the quenching
constant or the binding constant can be evaluated from modified
SterneVolmer (MSV) equation (3) [38].
I0
1
faKa
1
Q
1
fa
¼
þ
(3)
DI
where, DI is the difference in fluorescence intensity (i.e. I0eI) in the
absence (I0) and the presence (I) of the complexes at concentration
[Q], fa is the fraction of the BSA that is initially available to com-
plexes and Ka is the binding constant, by assuming that quenching
results due to the binding of complexes with BSA. Fig. 5a shows the
modified SterneVolmer plot and the binding constants (Table 4) for
all the complexes (1e4) have been found from the ratio of the
intercept to the slope of the linear MSV plot. A good linear MSV plot
again confirms that quenching mechanism between complexes and
BSA belongs to the static quenching.
Further, LineweavereBurk analysis has been made to obtain the
binding constant for the BSA-copper complexes. This analysis
(equation (4)) is based on a double reciprocal plot and is somewhat
similar to the MSV-equation.
Fig. 3. Fluorescence spectrum of BSA with different concentrations of 4.
1
1
1
Q
1
I0
¼
þ
(4)
I0 ꢀ I I0Ka
where, I0 and I are the fluorescence intensities in the absence and in
the presence of the complexes at concentration [Q]. Ka is the
binding constant and is calculated from the ratio of the intercept to
the slope of the straight line obtained from the LineweavereBurk
plot. This analysis provides binding constant for BSA-complexes
interaction (Fig. 5b) and the magnitude is almost same as that
obtained from MSV analysis.
Lastly, Scatchard method of analysis is based on Scatchard’s
equation (5) has been made, from which we can calculate the
binding constant and number of binding sites.
.
r
¼ nKa ꢀ rKa
(5)
Cf
where r (r ¼
DI/I0) is the moles of complex bound per mole of BSA,
Cf is the molar concentration of the free copper complex, n is
number of binding sites and Ka is the binding constant. Unlike the
MSV and LWB plots, the Scatchard plot (Fig. 6) shows a negative
slope as indicated by the sign in equation (5). The binding constant
for BSA-complexes interaction is the slope obtained from the
respective Scatchard plots. The magnitude of Ka values is compa-
rable with that of the binding constant obtained from MSV and LWB
analyses (Table 4).The number of binding sites has been calculated
from the ratio of the intercept to the slope obtained from the linear
plot.
Fig. 4. Stern-Volmer plot for the quenching of BSA by complexes (1e4).
Table 3
SterneVolmer quenching constants and quenching rate constants for BSA with 1e4.
Complexes
Ksv ꢃ 105 Mꢀ1
kq ꢃ 1013 Mꢀ1sꢀ1
4. Conclusion
1
2
3
4
1.37
1.52
0.77
1.64
2.26
2.51
1.27
2.71
We present here the preparation and characterization of a series
of four [Cu(NN)(PPh3)2]NO3 complexes with sterically hindered

6
L. Pathaw et al. / Journal of Molecular Structure 1207 (2020) 127821
Fig. 5. Determination of binding constant from (a) modified SterneVolmer plot and (b) LineweavereBurk plot.
bovine serum albumin and Cu(I) complexes were calculated using
modified Stern-Volmer, LineweavereBurk and Scatchard plots. All
the complexes exhibit the binding constants in the order of 104.
Table 4
Binding constants and binding sites for the interaction of BSA with 1e4.
Complexes
aKa ꢃ 104 Mꢀ1
bKa ꢃ 104 Mꢀ1
cKa ꢃ 104 Mꢀ1
n
1
2
3
4
3.47
9.32
6.96
13.36
3.47
9.33
6.98
12.63
7.05
9.05
1.99
17.31
1.54
1.36
1.47
0.97
CRediT authorship contribution statement
Larica Pathaw: Conceptualization, Methodology, Data curation,
Formal analysis, Writing - original draft. Themmila Khamrang:
Conceptualization, Methodology, Data curation, Formal analysis.
Arunkumar Kathiravan: Conceptualization, Methodology, Data
curation, Formal analysis, Writing - original draft, Writing - review
& editing. Marappan Velusamy: Data curation, Formal analysis,
Writing - original draft, Writing - review & editing.
a
from modified Stern-Volmer plot.
from LineweavereBurk plot.
from Scatchard plot.
b
c
Acknowledgements
M.V acknowledges Science and Engineering Research Board
(SERB), New Delhi EMR/2016/007955, Dated: 12. 03. 2018 for the
financial support.
Appendix A. Supplementary data
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.molstruc.2020.127821.
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