Synthesis, characterization, and DNA-binding studies of lanthanide(III) complexes Ln(H2L) · (HL) · 0.5(bipy)·nH 2O1

Article abstract of DOI:10.1080/15533174.2012.762380

A series of lanthanide(III) complexes Ln(H₂L) · (HL) · 0.5(bipy)·nH₂O (where Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, and H₃L = N-(2-propionic acid)-salicyloyl hydrazone, bipy = 2,2′-dipyridine) have been synthesized in ethanol-water mixture and characterized. The DNA-binding properties of these complexes were searched for the interaction with CT-DNA by electronic absorption titration and emission titration. The results showed that the interaction between Nd(III) complex and CT-DNA by surface/electrostatic binding, while all the other complexes can bind to calf-thymus DNA mainly by intercalation mode. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15533174.2012.762380

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Synthesis and Reactivity in Inorganic, Metal-Organic,
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Synthesis, Characterization and DNA-Binding Studies
of Lanthanide(III) Complexes Ln (H L) · (HL) ·
2
1
0
.5(bipy)·nH O
2
a
b c
b
b
Yingjuan Wang , Fingying Chen
, Wangting Wu & Shuiying He
a
College of Life science , Northwest University and Ministry of Education Key Laboratory
of Resouree Biology and Bioteechnology in western China, Northwest University;Xi’ an ,
Shaanxi , 710069 , P.R. China
b
College of Chemistry and Material Science , Northwest University and Key Laboratory
of Synthetic and Natural Functional Molecule Chemistry of Ministry Education, Xi’ an ,
Shaanxi , 710069 , P.R. China
c
Department of Chemistry , Shangluo University , Shangluo , 72600 , P.R. China
Accepted author version posted online: 13 May 2013.
To cite this article: Yingjuan Wang , Fingying Chen , Wangting Wu & Shuiying He (2013): Synthesis, Characterization and DNA-
1
Binding Studies of Lanthanide(III) Complexes Ln (H L) · (HL) · 0.5(bipy)·nH O , Synthesis and Reactivity in Inorganic, Metal-
2
2
Organic, and Nano-Metal Chemistry, DOI:10.1080/15533174.2012.762380
To link to this article: http://dx.doi.org/10.1080/15533174.2012.762380
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Synthesis, Characterization and DNA-Binding Studies of
1
Lanthanide(III) Complexes Ln (H
2
L) · (HL) · 0.5(bipy)·nH O
2
a
b,c
b
b*
Yingjuan Wang , Fingying Chen , Wangting Wu , Shuiying He
a. College of Life science , Northwest University and Ministry of Education Key Laboratory of
Resouree Biology and Bioteechnology in western China, Northwest University ;Xi’an, Shaanxi
710069, P.R. China
b College of Chemistry and Material Science, Northwest University and Key Laboratory of
Synthetic and Natural Functional Molecule Chemistry of Ministry Education, Xi’an, Shaanxi
7
10069, P.R. China
c Department of Chemistry Shangluo University, Shangluo 72600,P.R. China
e-mail: xdchemistry411@126.com
Abstract---A series of lanthanide (III) complexes Ln (H L) · (HL) · 0.5(bipy)·nH
Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb and H L=N-(2-propionic acid)-salicyloyl hydrazone,
*
2
2
O (where Ln
=
3
bipy= 2, 2 '-dipyridine) have been synthesized in ethanol-water mixture and characterized. The
DNA-binding properties of these complexes were searched for the interaction with CT-DNA by
electronic absorption titration and emission titration. The results showed that the interaction
between Nd(III) complex and CT-DNA by surface/electrostatic binding, while all the other
complexes can bind to calf thymus DNA mainly by intercalation mode.
Key words: Lanthanide(III) Complexes, DNA-binding, hydrazone
INTRODUCTION
1
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The DNA-binding metal complexes have been extensively studied as DNA structural probes,
DNA-dependent electron transfer probes and so on during the past decade [1-4]. DNA-binding
small molecules have since long attracted interest because of their interference with important
mechanisms in the cell, some inducing mutations and cancer, while others have found use as
cancer therapeutics [5]. Small molecules recognizing specific DNA sequences have attracted
great interest for gene-targeted drugs, which may alter the local structure of DNA to inhibit
access of activators or repressors to regulate ultimate gene expression processes [6]. The
interaction of lanthanide complexes, containing multidentate aromatic ligands, with DNA has
recently gained much attention following the important biological and medical roles [7, 8].
Aromatic ring stacking between nucleobases is considered to be a major driving force that leads
to binding. The size, electron density of the interacting aromatic rings and the combined effect of
hydrophobic and hydrophilic interactions determine the extent of binding [9-11]. Thus by using
mixed ligand complexes, it is possible to systematically vary parameters of interest hence
changing the properties of the intercalating groups without altering the chemical nature of the
intercalating moiety [12, 13]. In the previously published works [14], the crystal structure and
fluorescence properties of Dy(H
2
L)(HL)(bipy)·5H
2
O had been studied. This work is a
L)(HL)(bipy)·nH O (Ln=Ce, Pr,
continuation of our studies on mixed ligand complexes Ln(H
2
2
Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb). DNA binding properties of these complexes are studied by
electronic absorption titration and emission titration.
EXPERIMENTAL
Calf thymus DNA (CT-DNA) was purchased from Sigma (USA). Pyruvic acid was a
biochemical reagent. All the other chemicals used were of analytical grade.
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The C, H, and N analyses were taken with a Perkin Elmer model 2400 elemental analyzer. The
metal ion was determined by titration. Molar conductance measurement was made in DMF using
a
1
The article is published in the original.
DDS–11A conductivity meter. TG-DTG curves were measured by TG-209 gravitational thermal
analyzer. X-ray powder diffraction was performed using a D/max-III X-ray powder diffraction
apparatus. The UV spectra were recorded on a Lambda 40P UV-vis spectrophotometer.
Fluorescence measurements were made on a Hitachi F-4500 pectrophotometer.
Synthesis of the complexes. The Ln(NO
3
)
3
·nH
2
O, H L and bipy in 1:2:2 molar ratio were
3
dissolved in a mixed solution of water-ethanol, respectively, and then mixed. The resultant
solution was refluxed in 80°C in a water bath for 3 h, then cooled to room temperature, filtrated
and dried under vacuum.
DNA binding experiments The interaction of the complex with CT-DNA was studied in a
doubly distilled water buffer containing of tris(hydroxymethyl)aminomethane (Tris) (5 mmol),
0
.4% DMSO, and NaCl (5 mmol). The system was adjusted to pH 7.2 with hydrochloric acid. In
order to eliminate the absorbance of nucleic acid itself, an equal amount of CT-DNA was added
to the sample and the reference cell, respectively. Spectrometric titrations were performed
according to References [16–18].
RESULTS AND DISCUSSION
Composition of the Complexes
3
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The results of element analysis for all the complexes are listed in Table 1 along with their
formulae. From the data of table 1, it can be seen that the compositions of the complexes the
complexes are very similar except water molecular number. At the same time, the molar
conductivity in DMF of the complexes was also measured and the value was around 27.49–43.76
-1
2
-1
Ω ·cm ·mol , which shows that all the complexes are non-electrolytes in DMF [19].
Infrared Spectra
The important IR frequencies of the ligand and its complexes along with their relative
assignments are recorded in Table 2. IR spectra of the complexes and the (H
3
L) are identified
according to the literature [20, 21]. The bands appearing in the infrared spectra of the free ligand
�
1
(
H L) at 3291, 1642, 1756 cm are assigned to νN-H, νC=N and νCOOH respectively. All complexes
3
�
1
show a strong band in 1522-1538 cm assigned to ν(C=N) vibration, which indicates that the
-1
C=N (N atom) was coordinated. The absorption band at 1756 cm of free ligand H L(νCOOH) has
3
�
1
� 1
been replaced by two new bands around 1598-1612 cm and 1337-1358 cm in all the
complexes, which were assigned to νas, COO, and νs, COO respectively. The � ν (νas� ν ) is more than
00 cm which indicates that COO is coordi- nated with the lanthanide ion in the form of one
s
�
1
�
2
�
1
dentate[22]. The bands at 742-765 and 579-587 cm in all the complexes are assigned to the in-
plane and out-of-plane vibration of water which are associated with the coordinated water.
UV Spectra
UV Spectra of the ligand and the complexes were obtained in DMF solution with DMF as a
reference. The data are listed in Table 3. There are two bands at 273 and 313 nm in the ligand,
which is the π-π* transition of the salicyloyl group. They red shift to 284-302 and 325-331nm in
the complexes show that the coordination of the ligands.
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Fluorescence Properties
The emission spectrum of H L and Dy(III) complex were measured in the solid state at room
3
temperature. The excitation wavelength of the ligand and Dy(III) complex are 300 nm and 350
nm respectively. The fluorescence spectrum of the ligand and the complex are shown in Fig. 1.
The free ligand H
3
L shows two broad bands around 407 and 453 nm. Spectra exhibit a broad
band around 430 nm, attributed to the ligand and dipy. Three other peaks at 480, 575 and 645 nm
4
6
4
6
4
6
can be attributed to F9/2→ H15/2, F9/2→ H13/2 and F9/2→ H11/2 transitions of Dy(III),
respectively [24]. The fluorescence enhancement of Dy(III) reflects efficient energy transfer
3
+
from the conjugated π-electron system of the ligand to the Dy ion, as compared to Dy(NO
3
)
3
·
5
H
2
O under the same conditions. These observations suggest that the Dy(III) complex could be
anticipated as a potential fluorescent material.
X-Ray Powder Diffraction
The results of the X-ray powder diffraction for the salt (Gd(NO
3
)
3
·6H
2
O), ligand (H L), and the
3
complexes are shown in Table 4. The X-ray powder diffraction data on the salt were carried out
according to standard card no. 30-0553: Quality. From Table 4, it can be seen that X-ray power
diffraction of the complexes is obviously different from the ligands and the salt, and the complex
is not a simple lap joint of the ligands and the salt either. It can be deduced that a new complex is
formed.
Thermal Analysis of the Complexes
The typical TG-DTG analysis and DSC for the three selected samples (Pr(III) complex,
Gd(III) complex and Er(III) complex) were performed from 20 to 1000� at a heating rate of
-
1
1
0� ·min under N
2
atmosphere and the thermal decomposed procedure are deduced as Scheme
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1
. Theoretical and experimental mass loss data (%) for the thermal decomposition of the
complexes are listed in table 5. Upon heating under nitrogen, the complex undergoes three major
stages of weight loss. The first stage(20-280� )is connected with the loss of water from the
complexes; the second stage(280-340� ) is the loss of bipy ligand, and the last stage is the
decomposition of the ligands H L
3
Crystal structure
The structure of Dy(III) complex [14] and Eu(III) complex [15] showed in Fig.2. The
coordination environment around Eu and Dy are very similar. The metal atom is nine-
coordinated by two tridentate ligands and three water molecules in each complex.
DNA binding studies
Before reacting of the complexes with CT-DNA, their solution behaviors in a buffer solution at
room temperature were monitored by UV-vis spectroscopy for 24 h. No liberation of the ligand
was observed under these conditions. These suggest that all the complexes are stable under the
conditions studied.
Absorption spectral studies
The application of electronic absorption spectroscopy in DNA-binding studies is one of the
most useful techniques [24, 25]. The absorption spectra of all the complexes in the absence and
presence of DNA are shown in Fig. 3 and the values of the DNA binding are shown in table 6.
Upon increasing concentrations of DNA, all of the absorption bands of the complexes displayed
hypochromicities. The addition of DNA resulted in hypochromism ΔH% (ΔH%=100 (Afree
-
Abound)/Afree) for the π-π* absorption at about 280 nm of 64%, 53%, 33%, 61% and 35% for
Ce(III) complex, Eu(III) complex, Gd (III)complex, Tb(III)complex and Yb(III) complex,
6
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respectively. As reported previously [26], the hypochromism of 26% was obtained upon the
2
+
addition of DNA to [Ru(bpy) (pip)] implied the interaction of the complex with DNA by an
2
intercalative mode. So these five complexes interact with calf thymus DNA quite probably by
intercalating the ligand into the base pairs. While for the other complexes, the hypochromism of
the absorption bands are all less than 26%, so the interaction modes of these complexes with
DNA need to confirm by further experiments.
Emission spectral studies
The emission spectra of the complexes in the absence and presence of DNA are illustrated in
–
6
–6
–6
–6
–6
Fig. 4. We used [DNA] = 0, 10 × 10 , 20×10 , 30 ×10 , 40×10 and 50×10 mol/L. Arrow
shows the absorbance changes upon increasing DNA concentration. All of the complexes can
emit strong luminescence in Tris buffer. For Ce(III) complex, Eu (III)complex, Gd (III)complex,
Tb(III) complex and Yb(III) complex, the emission intensities at maximum wavelength increase
about 1.15-1.85 times with increasing concentrations of CT-DNA. The results of the emission
titrations also indicate that the complexes are protected from solvent water molecules by the
hydrophobic environment inside the DNA helix. This implies that the complexes can insert
between DNA base pairs, which also agrees with those observed for the UV. For Er complex, the
F/F0=1.40. This phenomenon also implies that the complex is protected by DNA, so the
interaction mode between Er complex and DNA may probably be an intercalative mode.
�
Luminescence Quenching by K
Steady-state emission quenching experiments using K
used to gauge the DNA binding properties of Pr(III) complex, Nd (III)complex, Sm (III)complex
4
[Fe(CN)
6
]
4
[Fe(CN) ] as the quencher were also
6
and Dy(III) complex. Anionic quenchers such as K
4
[Fe(CN) ], very efficiently quench the
6
7
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emission of complexes which are free in solution due to ion pairing [27] but poorly quench the
emission of complexes which are closely bound to the DNA polyanion. The emission quenching
spectra of the four complexes in the absence and presence of DNA are shown in Fig. 5. Figure 6
shows Stern Volmer plots for the emission quenching of these four complexes by K
4
[Fe(CN)
6
] in
the absence and presence of DNA. For Nd (III)complex, with increasing K [Fe(CN)
4
6
] quencher
concentrations, the system of the complex and complex-DNA causes obvious reduction in the
emission intensity, but the emission intensity of complex in the absence of DNA is higher than
that in the presence of DNA under the same K
DNA can not protect Nd(III) complex from quenching by K
between Nd(III) complex and DNA may probably be surface/electrostatic binding. For Pr(III)
complex, Sm(III) complex and Dy(III) complex, with increasing K [Fe(CN) ] quencher
4
[Fe(CN)
6
] quencher concentration, indicating that
4
[Fe(CN) ]. So the interaction mode
6
4
6
concentrations, the system of these complexes and complex-DNA causes obvious reduction in
the emission intensity, but the emission intensity of complex in the absence of DNA are less than
that in the presence of DNA under the same K
4
[Fe(CN)
6
] quencher concentration, indicating
[Fe(CN) ] quencher in the presence
that the complex binds to DNA and is protected from the K
4
6
of DNA..
ACKNOWLEDGMENTS
The work was supported by the impotant item 13115 of Shaanxi Province science and
technology office (No. 08ZDKG-12), National Science Foundation of China (No. 30970308) and
the National Science Foundation of China (No. 21273171).
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4
3
5.0
7.5
450
400
350
300
250
200
150
30.0
22.5
15.0
7
.5
.0
0
350
400
450
500
550
400.0 450.0 500.0 550.0 600.0 650.0
Wavelength(nm)
Wavelength/nm
Fig.1 Fluorescence spectra of H
3
L (left) and Dy(III) complex (right) in the solid state.
1
0
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Fig. 2. Perspective view of coordination for Eu(III) complex (left) and Dy(III) complex (right),
where H atom are omitted for clarity
1
0
0
0
.0
.9
.8
.7
.6
.5
.4
.3
.2
.1
.0
0
.6
Pr(III)complex
+DNA
ce(III) complex
DNA
0.5
+
0.4
0.3
0
0
0
0
0
0
0
0
.2
.1
0.0
0
2
50 275 300 325 350 375 400
250 275 300 325 350 375 400
wavelength(nm)
wavelength (nm)
0
.6
0.5
.4
.3
.2
0.1
.0
1
.5
.2
.9
.6
.3
.0
Nd(III) complex
Sm(III) complex
+DNA
1
0
+DNA
0
0
0
0
0
0
0
2
50 275 300 325 350 375 400
280
320
360
400
wavelength(nm)
Wavelength(nm)
1
1
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0
.6
.5
.4
.3
.2
.1
.0
0.9
.8
.7
0.6
.5
.4
0.3
.2
.1
0.0
0
0
Eu(III) complex
DNA
Gd(III) complex
DNA
0
0
+
+
0
0
0
0
0
0
0
0
2
50 275 300 325 350 375 400
250 275 300 325 350 375 400
wavelength (nm)
wavelength(nm)
1
.2
.0
.8
.6
.4
.2
.0
0
.7
0.6
.5
0.4
.3
.2
0.1
.0
1
Dy(III) complex
+DNA
Tb(III) complex
DNA
0
0
+
0
0
0
0
0
0
0
2
50 275 300 325 350 375 400
2
50 275 300 325 350 375 400
wavelength (nm)
wavelength(nm)
0
0
0
0
0
0
0
.6
.5
.4
.3
.2
.1
0.9
0
.8
.7
Er(III) complex
+DNA
0
Yb(III) complex
DNA
0.6
+
0
0
0
0
0
0
.5
.4
.3
.2
.1
.0
2
.0
2
50 275 300 325 350 375 400
wavelength (nm)
50
300
wavelength (nm)
350
400
–
4
Fig. 3. Electronic spectra of Ln (H
2
L) · (HL) · 0.5(bipy)·nH O (1.0×10 mol/L) in the presence
2
–
6
–6
–6
–6
–6
of increasing amounts of CT-DNA, [DNA] = 0, 10×10 , 20×10 , 30 ×10 ,40×10 and 50×10
mol/L.
1
2
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1
000
1800
1600
Ce(III) complex
F/F0=1.15
Pr(III) complex
F/F0=1.13
8
00
00
00
00
1
400
200
000
00
00
00
00
1
+DNA
6
4
2
1
+DNA
8
6
4
2
300
350
400
wavelength (nm)
450
500
3
25 350 375 400 425 450 475 500 525
wavelength (nm)
1
800
600
400
200
000
00
00
00
00
1
400
200
1000
00
00
00
00
1
Nd(III) complex
F/F0=1.10
1
1
Sm(III) complex
F/F0=1.12
1
+DNA
+DNA
1
8
8
6
6
4
4
2
2
0
3
0
300
00
350
400
450
500
350
400
450
500
wavelength (nm)
wavelength(nm)
1
200
000
00
00
00
00
1400
200
1000
00
00
00
1
1
Gd(III) complex
F/F0=1.30
Eu(III) complex
F/F0=1.85
8
8
6
+
DNA
+DNA
6
4
4
2
200
0
3
0
3
00
350
400
450
500
00
350
400
wavelength (nm)
450
500
wavelength (nm)
1
3
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2
00
80
60
40
20
00
1200
000
800
00
400
00
1
Tb(III) complex
F/F0=1.32
1
Dy(III) complex
F/F0=1.09
1
+DNA
1
1
+DNA
6
1
8
0
6
0
2
4
0
20
300
0
300
350
400
wavelength (nm)
450
500
350
400
450
500
wavelength (nm)
2
800
400
000
600
200
00
00
1600
400
200
000
00
00
00
00
1
2
Er(III) complex
F/F0=1.40
Yb(III) complex
F/F0=1.15
1
2
1
1
+DNA
+DNA
8
1
6
8
4
4
2
0
3
0
300
00
350
400
wavelength (nm)
450
500
350
400
450
500
wavelength (nm)
–
4
Fig. 4. The emission enhancement spectra of the complexes (1.0 × 10 mol/L) in the presence
–
6
–6
–6
–6
–6
of 0, 10 × 10 , 20 × 10 , 30 ×10 ,40×10 and 50×10 mol/L
2
00
5
00
00
00
00
00
Pr(III) complex
+K4[Fe(CN)6]
Pr(III) complex-DNA
K4[Fe(CN)6]
4
150
+
3
100
2
5
0
1
0
0
3
00
350
400
450
500
3
00
350
400
450
500
wavelength/nm
Wavelength/nm
1
4
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
1
20
00
300
50
00
50
00
Nd(III) complex-DNA
K4[Fe(CN)6]
Nd(III) complex
K4[Fe(CN)6]
2
1
+
+
2
8
6
4
2
0
0
0
0
1
1
50
0
500
500
510
520
530
540
550
510
520
530
540
550
wavelength/nm
Wavelength/nm
1
20
100
80
60
40
20
0
1
20
00
Sm(III) complex-DNA
+K4[Fe(CN)6]
Sm(III) complex
K4[Fe(CN)6]
1
+
8
6
4
2
0
0
0
0
0
3
00
350
400
450
500
300
350
400
450
500
wavelength/nm
Wavelength/nm
2
50
00
50
00
50
1
00
Dy(III) complex-DNA
K4[Fe(CN)6]
2
8
6
4
2
0
0
0
0
0
Dy(III) complex
+
+K4[Fe(CN)6]
1
1
5
00
510
520
530
540
550
500
510
520
530
540
550
wavelength(nm)
wavelength/nm
Fig.5. Emission quenching spectra of complexes and complex-DNA (b) with increasing of
–4
–3
concentration of the K
4
[Fe(CN)
6
] quencher. c complex= 1.0 × 10 mol/L, c K4[Fe(CN)6] = 0, 1× 10 ,
–
3
–3
–6
2
× 10 and 3× 10 mol/L, and c DNA = 40 × 10 mol/L.
1
5
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
6
5
4.5
.0
.5
.0
2.5
.0
.5
.0
0.5
4
3
4
3
Pr(III) complex
Nd(III) complex-DNA
3
2
2
1
1
Pr(III) complex-DNA
1
Nd(III) complex
0
0
-
3
-3
-3
-3
-3
-3
.0
0.0
1.0x10
2.0x10
3.0x10
1
.0x10
2.0x10
K4[Fe(CN)6]
3.0x10
c
cK4[Fe(CN)6]
4
.0
.5
.0
.5
.0
.5
.0
.5
10
8
3
3
Dy(III) complex
Sm(III) complex
6
2
2
4
1
Sm(III) complex-DNA
2
1
Dy(III) complex-DNA
0
0.0
0
-
3
-3
-3
-
3
-3
-3
1.0x10
2.0x10
3.0x10
0.0
1
.0x10
2.0x10
K4[Fe(CN)6]
3.0x10
c
c
K4[Fe(CN)6]
Fig.6. Stern–Volmer plot of complexes for the steady-state emission quenching by K
4
[Fe(CN) ].
6
Scheme 1.
20-280�
281-343�
Ln
Ln
2
-nH O
-0.5bipy
344-996�
Ln (H
2
L)(HL)
Ln
2
O
3
/Ln
6
O11+n
Table 1 Element analysis data and molar conductance for the complexes
-
m
Λ /Ω
complexes
C%
H%
N%
Ln%
1
2
-1
·
cm ·mol
Ce(H
2
L)(HL)·0.5(bipy)·8 37.33(37. 4.66(4. 8.55(8.7 17.66(17.
29.34
1
6
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
H
2
O
36)
40.95(40. 3.89(3. 10.06(9. 19.53(19.
99) 99) 56) 24)
38.85(38. 3.94(3. 9.59(9.5 19.55(19.
91) 99) 6) 24)
38.41(38. 3.99(4. 9.00(9.0 19.58(l9.
60) 28) 0) 33)
38.45(38. 4.20(4. 8·75(8.9 19.15(19.
52) 27) 8) 49)
39.33(39. 4.27(4. 9.06(9.1 20.33(20.
16) 07) 3) 51)
37.66((37 4.31(4. 8.52(8.7 20.00(19.
.32) 39) 1) 75)
38.90(38. 4.36(4. 9.34(9.0 21.03(21.
89) 05) 7) 05)
36.81(36. 4.35(4. 8.62(8.6 20·26(20.
94) 34) 2) 58)
35.99(35. 4.29(4. 8.37(8.3 20.48(20.
89) 46) 7) 68)
64)
1)
43)
Pr(H
bipy)·4H
Nd(H L)(HL)·0.5
bipy)·6H
Sm(H L)(HL)·0.5
bipy)·6H
Eu(H L)(HL)·0.5
bipy)·6H
Gd(H L)(HL)·0.5
bipy)·5H
Tb(H L)(HL)·0.5
bipy)·7H
Dy(H L)(HL)·0.5
bipy)·5H
Er(H L)(HL)·0.5
bipy)·7H
Yb(H L)(HL)·0.5
bipy)·8H
2
L)(HL)·0.5
3
3
3
3
4
3
3
3
2
2.56
4.29
5.67
7.09
3.76
0.59
6.02
6.47
7.49
(
2
O
2
(
2
O
2
(
2
O
2
(
2
O
2
(
2
O
2
(
2
O
2
(
2
O
2
(
2
O
2
(
2
O
�
1
Table 2 Important Infrared Spectra Data of the Complexes(cm )
1
7
ACCEPTED MANUSCRIPT

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as
s
ν
COO
H
ν
COO
ν
COO
ν
C=N
ρ
O-H
ω
O-H
samples
ν
C=N
ν
N-H
-
-
(bipy)
—
(H
2
O)
(H O)
2
329
H
3
L
1756
—
—
—
—
1642
—
—
—
—
—
1
bipy
—
1458
1453
—
323
5
Ce(H
2
L)(HL)·0.5(bipy
—
1612 1342 1530
754
579
)
·8H
L)(HL)·0.5
bipy)·4H
Nd(H L)(HL)·0.5
bipy)·6H
Sm(H L)(HL)·0.5
bipy)·6H
Eu(H L)(HL)·0.5
bipy)·6H
Gd(H L)(HL)·0.5
bipy)·5H
Tb(H L)(HL)·0.5
bipy)·7H
Dy(H L)(HL)·0.5
bipy)·5H
Er(H L)(HL)·0.5
2
O
Pr(H
2
327
7
—
—
—
—
—
—
1616 1357 1531 ,1454
765
758
750
761
753
763
582
581
583
583
585
587
(
2
O
2
326
8
1602 1358 1522
1600 1341 1538
1611 1344 1530
1608 1337 1536
1598 1338 1526
1454
1456
1454
1454
1455
(
2
O
2
325
3
(
2
O
2
325
4
(
2
O
2
328
4
(
2
O
2
324
8
(
2
O
2
325
2
—
—
1608 1339 1533
1610 1341 1537
1454
1454
742
762
583
586
(
2
O
2
323
1
8
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
(
bipy)·7H
Yb(H L)(HL)·0.5
bipy)·8H
2
O
5
324
5
2
—
1610 1341 1536
1453
761
586
(
2
O
Table 3 Ultraviolet Spectral Data for the Ligand and Complexes
5
-1
�
�
c×10 (mol·l )
λ (π-π*) (nm)
H
3
L
9.01
313
325
273
302
Ce (H
0.5bipy·8H
Pr (H L)(HL)
0.5bipy·4H
Nd (H L)(HL)
2
L)(HL)
1.81
·
2
O
2
2.13
1.55
1.59
1.00
1.41
1.54
1.65
326
331
327
327
326
327
328
301
284
289
287
288
302
289
·
2
O
2
·
0.5bipy·6H
2
O
Sm (H L)(HL)
2
·
0.5bipy·6H
2
O
Eu (H L)(HL)
2
·
0.5bipy·6H
2
O
Gd (H L)(HL)
2
·
0.5bipy·5H
2
O
Tb (H L)(HL)
2
·
0.5bipy·7H
2
O
Dy (H L)(HL)
2
1
9
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
·
0.5bipy·5H
Er (H L)(HL)
0.5bipy·7H
Yb (H L)(HL)
0.5bipy·8H
2
O
2
1.80
1.79
326
329
301
302
·
2
O
2
·
2
O
Table 4 Data of X-ray for the ligand, salt, and complex
X-ray powder diffraction data
sample
I/I
0
100
70
40
40
25
25
25
20
Gd(NO
3
)·4H O
2
d/nm 0.792 0.540 0.547 0.260 0.614 0.515 0.387 0.377
I/I 100 82 73 61 55 46 40 I/I
0
0
H
3
L
d/nm 0.3601 0.3386 0.3684 0.5611 0.5764 0.6021 0.4691 d/nm
I/I 100 85 67 59 50 40 35 34
Gd(III)
0
d/nm 1.4430 1.2405 0.5933 0.6146 0.5528 0.5181 0.4721 0.8434
complex
Table 5 Theoretical and experimental mass loss data (%) for the thermal decomposition of the
three complexes
sample
fragment
loss%
fragment
loss%
fragment
loss%
residue
residue%
1
H
2
O
O
2.92(2.
46)
11.0 2C
6
H
5
O
41.1 Pr
2
6
O
1
bipy
27.30
(27.0
7)
Pr(III)
complex
3H
2
2
+ 4CO
1
2
80~34
30~28 8.03(7.
37)
(10.6 340~39 (40.6 +3C
6) 2� 8) 995.1
0
�
0
�
2
0
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
�
2
3
H
H
2
2
O
O
4.96(4.
69)
Gd O
2
1
0.9
24.2
6
bipy
2C
6
H
5
O
3
25.79
(25.1
7)
Gd(III)
8
3
0~28 7.13(7. 280~34
343~52
+C
896.2
�
complex
(10.1
(24.2
6)
0
�
04)
3�
5�
8
)
4
H
2
2
O
O
8.06(8.
86)
22.8 Er
+2C
(23.2 994.5
6)
2
O
3
bipy
9.61 2C
6
H
5
O
27.03
(26.4
8)
Er(III)
3H
8
2
28~34 (10.8 342~54
complex
32~22 7.02(6.
64)
2
�
1) 5�
8
�
�
Table 6 Absorption spectroscopic properties of Ln(III) complexes on binding to CT-DNA
λmax (nm)
Change in
absorbance
Red shift
(nm)
ΔH(
%)
58,
64
compound
free
bound
Ce(H
0.5bipy·8H
Pr (H L)(HL)
0.5bipy·4H
Nd(H L)(HL)
2
L)(HL)
281, 330
1, -3
2
2
2
81, 330
80, 331
81, 332
Hypochromism
Hypochromism
Hypochromism
·
2
O
2
280, 334
281, 333
0, 3
0, 1
0, 5
13,
23
·
2
O
2
5, 0
7, 4
·0.5bipy·6H
2
O
Sm(H
2
L)(HL)
281, 325 281, 330 Hypochromism
2
1
ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
·
0.5bipy·6H
Eu(H L)(HL)
0.5bipy·6H
Gd(H L)(HL)
0.5bipy·5H
Tb(H L)(HL)
0.5bipy·7H
Dy(H L)(HL)
0.5bipy·5H
Er (H L)(HL)
0.5bipy·7H
Yb(H L)(HL)
0.5bipy·8H
2
O
2
285, 335
286, 335
4, 5
3, 9
53,
30
2
2
2
2
2
2
81, 330
83, 326
Hypochromism
Hypochromism
·
2
O
2
33,
47
·
2
O
2
3, 5
61,
65
81, 331 284, 336 Hypochromism
283, 326
·
2
O
2
1, -3
0, -2
1, -1
17,
20
82, 329
83, 331
82, 331
Hypochromism
Hypochromism
Hypochromism
·
2
O
2
283, 329
283, 330
13,
21
·
2
O
2
35,
48
·
2
O
2
2
ACCEPTED MANUSCRIPT