Synthesis and DNA-binding properties of a cationic seven-coordinate manganese(II) complex formed with the tripodal ligand Tris(Nmethylbenzimidazol- 2-ylmethyl)amine and salicylate

Article abstract of DOI:10.5560/ZNB.2012-0082

A ternary cationic Mn(II) complex with the tripodal ligand tris(2-(N-methyl) benzimidazylmethyl)amine (Mentb), salicylate and DMF as ligands and nitrate as counterion, [Mn(Mentb)(salicylate)DMF](NO₃), was synthesized and characterized by physico-chemical and spectroscopic methods. The crystal structure of the Mn(II) complex has been determined by single-crystal X-ray diffraction and revealed that the central Mn(II) atom is seven-coordinated. The DNA-binding properties of the Mn(II) complex were investigated by spectrophotometric methods and viscosity measurements, and the results suggest that the Mn(II) complex binds to DNA via an intercalation binding mode. Additionally, the complex exhibited potential hydroxyl radical scavenge properties in in vitro studies.

Full text of DOI:10.5560/ZNB.2012-0082

Synthesis and DNA-binding Properties of a Cationic Seven-coordinate
Manganese(II) Complex Formed with the Tripodal Ligand Tris(N-
methylbenzimidazol-2-ylmethyl)amine and Salicylate
Huilu Wu, Ying Bai, Jingkun Yuan, Hua Wang, Guolong Pan, Gangqiang Yu, and
Xingbin Shu
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070,
P. R. China
Reprint requests to Prof. Huilu Wu. E-mail: wuhuilu@163.com
Z. Naturforsch. 2012, 67b, 819 – 826 / DOI: 10.5560/ZNB.2012-0082
Received March 20, 2012
A
ternary cationic Mn(II) complex with the tripodal ligand tris(2-(N-methyl)
benzimidazylmethyl)amine (Mentb), salicylate and DMF as ligands and nitrate as counterion,
[Mn(Mentb)(salicylate)DMF](NO3), was synthesized and characterized by physico-chemical and
spectroscopic methods. The crystal structure of the Mn(II) complex has been determined by
single-crystal X-ray diffraction and revealed that the central Mn(II) atom is seven-coordinated. The
DNA-binding properties of the Mn(II) complex were investigated by spectrophotometric methods
and viscosity measurements, and the results suggest that the Mn(II) complex binds to DNA via an
intercalation binding mode. Additionally, the complex exhibited potential hydroxyl radical scavenge
properties in in vitro studies.
Key words: Manganese(II) Nitrate Complex, Crystal Structure, DNA-binding Properties,
Tris(2-(N-methyl)benzimidazolylmethyl)amine (Mentb)
Introduction
for their potential to poison DNA topoisomerases
or to stabilize complexes of DNA topoisomerases
DNA is generally the primary intracellular target that ultimately result in strand cleavage [9, 10].
of anticancer drugs. The interaction between small In previous work we reported on the perchlo-
molecules and DNA can often cause DNA damage in rate of a cationic Mn(II) complex with tris(2-(N-
cancer cells, blocking the division of cancer cells and methyl)benzimidazolylmethyl)amine (Mentb), salicy-
resulting in cell death [1, 2]. Transition metal com- late, and DMF as ligands [11, 12]. Now we give a full
plexes are used to bind and react at specific sequences account on the synthesis, crystal structure and DNA-
of DNA for finding novel chemotherapeutics, prob- binding properties of the respective nitrate salt of the
ing DNA and developing highly sensitive diagnostic Mn(II) complex.
agents [3, 4]. Manganese is an essential element in
the human body. It plays an important role in many
biological systems including photosystem II (water
oxidation), catalase (disproportionation of hydrogen
peroxide), and superoxide dismutase (dismutation of
superoxide radicals) [5 – 7]. Research on how Mn(II)
complexes interact with DNA is expected to help in
the development of relevant drugs.
Experimental Section
Materials and physical measurements
All chemicals used were of analytical grade. Ethidium
bromide (EB) and calf thymus DNA (CT-DNA) were pur-
chased from Sigma and used without further purification. All
the experiments involving interaction of the ligand and the
complex with CT-DNA were carried out in doubly distilled
water with a buffer containing 5 mM Tris and 50 mM NaCl
Benzimidazole can function as a ligand toward
transition metals in a variety of biologically im-
portant molecules [8]. Benzimidazoles are known and adjusted to pH = 7.2 with hydrochloric acid. A solution
c
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H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
of CT-DNA gave a ratio of UV absorbance at 260 and 280 nm 21.03. – UV/Vis: λ = 279, 289 nm. – FT-IR (KBr): ν = 1288
of about 1.8 – 1.9, indicating that the CT-DNA was suffi- (C–N); 1477 (C=N); 1614 (C=C) cm−1 [16, 17].
ciently free of protein [13]. The CT-DNA concentration per
Preparation of [Mn(Mentb)(salicylate)DMF](NO3)
nucleotide was determined spectrophotometrically by em-
ploying an extinction coefficient of 6600 L mol−1 cm−1 at
260 nm [14].
To a stirred solution of Mentb (0.449 g, 1 mmol) in hot
MeOH (10 mL) Mn(NO3)2 (0.358 g, 1 mmol) in MeOH
(5 mL) was added, and subsequently soldium salicylate
(0.160 g, 1 mmol) in hot MeOH (5 mL). A colorless prod-
uct formed rapidly. The precipitate was filtered off, washed
with MeOH and absolute Et2O, and dried in vacuo. The dried
precipitate was dissolved in DMF to form a colorless solution
into which Et2O was allowed to diffuse at room temperature.
Colorless crystals suitable for X-ray measurement were ob-
tained after three weeks. Yield: 0.454 g (47%). – Analysis for
C37H39MnN9O7: calcd. C 49.34, H 3.90, N 16.92; found C
50.47, H 4.08, N 16.76. – UV/Vis: λ = 260, 279 nm. – FT-IR
(KBr): ν = 1250 ν(C-N); 1458 ν(C=N); 1626 ν(C=C); 1593
C, H, and N contents were determined using a Carlo
Erba 1106 elemental analyzer. The IR spectra were recorded
in the 4000 – 400 cm−1 region with a Nicolet FI-VERTEX
70 spectrophotometer using KBr pellets. Electronic spec-
tra were taken on Lab-Tech UV Bluestar and Spectrumlab
722sp spectrophotometers. The fluorescence spectra were
performed on a LS-45 spectrofluorophotometer at room tem-
perature. Viscosity experiments were conducted on an Ubbe-
lodhe viscometer, immersed in a thermostated water bath
maintained at 25 ± 0.1 ◦C.
Preparation of
tris(2-(N-methyl)benzimidazylmethyl)amine (Mentb)
ν
as(O-C-O); 1488 νs(O-C-O); 1388 ν(N-O) cm−1
.
X-Ray crystal structure determination
Mentb was synthesized by literature methods [15]. Yield:
4.62 g (51%). M. p.: 215 – 217 ◦C. – Analysis for C27H27N7:
A suitable single crystal was mounted on a glass fiber.
calcd. C 72.14, H 6.05, N 21.81; found C 72.27, H 6.17, N The intensity data were collected on a Bruker Smart CMN
Table 1. Crystal and structure re-
[Mn(Mentb)(salicylate)DMF](NO3)
C37H39MnN9O7
776.71
finement
data
for
[Mn(Mentb)
Molecular formula
Molecular weight
Color
(salicylate)DMF](NO3).
colorless
Crystal size, mm3
Crystal system
Space group
0.40×0.38×0.30
triclinic
¯
P1
˚
a, A
10.468(5)
˚
b, A
12.564(6)
˚
c, A
15.209(8)
α, deg
β, deg
84.425(5)
76.049(5)
77.667(6)
1894.3(16)
2
γ, deg
3
˚
V, A
Z
Dcalcd., g cm−3
1.36
F (000)
810
θ range data collection, deg
hkl range (max / min)
Reflections collected / independent
Rint
2.19 – 26.00
−12 / 12, −15 / 14, −18 / 18
14309 / 7285
0.0381
Data / restraints / ref. parameters
Final R1 / wR2a[I > 2 σ(I)]
Final R1 / wR2 (all data)
Goodness-of-fit on F2 b
7285 / 29 / 493
0.0644 / 0.1697
0.1136 / 0.2005
1.024
−3
˚
Largest diff. peak / hole, e A
1.055 / −0.646
a
R1 = Σ||Fo| − |F ||/Σ|Fo|; wR2 = [Σw(Fo2 − F2)2/Σw(Fo2)2]1/2
,
w = [σ2(Fo2) +
c
c
(0.0963P)2 + 1.0515P]−1, where P = (Max(Fo2,0) + 2F2)/3; GoF = S = [Σw(Fo2
−
b
c
F2)2/(nobs − nparam)]1/2, where nobs is the number of data and nparam the number of re-
c
fined parameters.
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H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
821
˚
Table 2. Selected bond lengths (A)
and angles (deg) for [Mn(Mentb)
(salicylate)DMF](NO3).
Bond lengths
Mn–N1
Mn–N5
Mn–O1
Mn–O7
2.537(3)
2.294(3)
2.249(3)
2.285(4)
Mn–N3
Mn–N7
Mn–O2
2.201(4)
2.273(4)
2.420(3)
Bond angles
N3–Mn–O1
O1–Mn–N7
O1–Mn–O7
N3–Mn–N5
N7–Mn–N5
N3–Mn–O2
N7–Mn–O2
N5–Mn–O2
O1–Mn–N1
O7–Mn–N1
O2–Mn–N1
144.55(13)
90.41(13)
83.57(14)
100.27(13)
103.58(13)
89.90(12)
144.07(12)
89.54(12)
143.37(11)
120.10(14)
146.73(11)
N3–Mn–N7
N3–Mn–O7
N7–Mn–O7
O1–Mn–N5
O7–Mn–N5
O1–Mn–O2
O7–Mn–O2
N3–Mn–N1
N7–Mn–N1
N5–Mn–N1
119.52(13)
82.44(14)
82.11(14)
89.48(12)
171.08(14)
55.91(11)
81.95(14)
70.66(12)
68.07(12)
68.70(11)
diffractometer with graphite-monochromatized MoKα radia- trogen atoms to Mn(II). The complex shows two bands
at 1593 and 1488 cm−1 (∆ν = 105 cm−1) attributable
˚
tion (λ = 0.71073 A) at 293 K. Data reduction and cell re-
finement were performed using the program SAINT [18],
and an empirical absorption correction was performed using
to νas(O-C-O) and νs(O-C-O), indicating a bidentate
coordination [24 – 26] of the salicylate anion [27]. The
bands at 1388, 881 and 748 cm−1 indicate that a nitrate
SADABS [19]. The structure was solved by Direct Meth-
ods and refined by full-matrix least-squares against F2 us-
anion (D3h) is present [27].
ing SHELXTL [20]. All H atoms were found in difference
electron maps and were subsequently refined in a riding
model approximation with C–H distances ranging from 0.93
Molecular structure of the complex
˚
to 0.97 A and Uiso(H) = 1.2 Ueq(C). Crystal data and num-
The ORTEP plot of the [Mn(Mentb)(sali-
cylate)DMF] cation with the atom numbering
adopted is shown in Fig. 1.
bers pertinent to data collection and structure refinement are
given in Table 1. Selected bond lengths and angles are listed
in Table 2.
The asymmetric unit of the complex consists of
a [Mn(Mentb)(salicylate)DMF] cation and a nitrate
anion. The Mentb ligand forms a tripodal pyramidal
geometry with the manganese ion, and the remain-
ing coordination sites of the complex are occupied by
a chelating salicylate anion and a monodentate DMF.
The structure of the [Mn(Mentb)(salicylate)DMF]
CCDC 870603 contains the supplementary crystallo-
graphic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data request/cif.
Results and Discussion
The nitrate of the Mn(II) complex is soluble cation is similar to the previously reported one in
in DMF and DMSO, but insoluble in water and the perchlorate [11, 12]. The bond length between
organic solvents, such as methanol, ethanol, ben- the manganese ion and the apical nitrogen atom N1–
˚
˚
zene, petroleum ether, trichloromethane, etc. The Mn is 2.537(3) A which is about 0.281 A longer than
elemental analysis confirms its composition as the bond lengths between the manganese ion and
˚
[Mn(Mentb)(salicylate)DMF](NO3).
the basal nitrogen atoms (2.201(4) – 2.294(3) A, aver-
˚
The IR and UV spectra of the title complex are sim- age = 2.256 A). This significant elongation has been
ilar to that of the previously reported perchlorate salt observed in other manganese complexes with tripo-
of the Mn(II) complex [12]. The free ligand (Mentb) dal tetradentate ligands with a benzimidazolylmethyl
shows two strong bands at 1288 and 1477 cm−1, at- group [28]. The average bond angle NA–Mn–NB of
tributable to ν(C-N) and ν(C=N) [21 – 23], but two the axial nitrogen atoms (NA = N1), the manganese
strong bands are found for the complex at 1250 and ion, and◦the basal nitrogen atoms (NB = N3, N5, N7)
1458 cm−1. These bands are shifted to lower fre- is 69.14 , and the manganese ion is 0.801 A above the
˚
quencies by ca. 19 – 38 cm−1 upon complex formation trigonal basal plane. The oxygen atom of the monoden-
which implies direct coordination of the three imine ni- tate DMF is coordinated in trans position to the basal
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H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
Fig. 1. Molecular struc-
ture of [Mn(Mentb)(salicy-
late)DMF]NO3 with crys-
tallographic atom num-
bering adopted (hydrogen
atoms omitted for clarity)
and a representation of the
manganese
coordination
sphere (left).
N5 atom (N5–Mn–O7 = 171.08(14)◦). The oxygen the intense absorption bands observed in the ligand and
atoms of the chelating salicylate group are coordinated complex are attributed to intra-ligand π-π∗ transitions.
to the approximate trans positions of the remaining From the absorption titration data, the binding constant
two basal nitrogen atoms (O1–Mn–N3 = 144.55(13)◦, was determined using the following equation [30]:
O2–Mn–N7 = 144.07(12)◦). The additional ligands
are accommodated at the opened axial site without sig- [DNA]/(εa −εf) = [DNA]/(εb −εf)+1/Kb(εb −εf)
nificant change in the trigonal-pyramidal part of the
complex (N3–Mn–N7 = 119.52(13)◦). Steric crowd- where [DNA] is the concentration of DNA in base
ing of the ligands is avoided because the manganese(II) pairs, εa corresponds to the extinction coefficient ob-
ion is positioned slightly below the trigonal basal served (Aobsd/[M]), εf corresponds to the extinction
plane.
coefficient of the free compound, εb is the extinction
coefficient of the compound when fully bound to DNA,
and Kb is the intrinsic binding constant. The ratio of
slope to intercept in the plot of [DNA]/(εa− εf) vs
[DNA] gives the values of Kb. The absorption spec-
tra of the Mn(II) nitrate complex in the absence and
DNA-binding properties
Electronic absorption
The application of electronic absorption spec- presence of CT-DNA are given in Fig. 2.
troscopy in DNA-binding studies has proven to be one
With increasing DNA concentrations, the
of the most useful techniques [29]. Absorption titration hypochromisms is 45.9% at 260 nm for the Mn(II)
experiments were performed with fixed concentrations complex, suggesting that the Mn(II) complex in-
of the complex, while gradually increasing the concen- teracts with CT-DNA [31]. The Kb value of the
tration of DNA. While measuring the absorption spec- Mn(II) complex is 6.56 × 104 L mol−1 (R = 0.9988
tra, a proper amount of DNA was added to both the for 15 points). Therefore, by comparison of these
compound solution and the reference solution to elim- data with a DNA-intercalating ruthenium complex
inate the absorbance of DNA itself. In the UV region, (Kb = 1.1 × 104 − 4.8 × 104 L mol−1) [32] one can
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H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
823
Fig. 2. Electronic spectra of the complex in Tris-HCl buffer upon addition of CT-DNA. [Complex] = 3 × 10−5 L mol−1
,
[DNA] = 2.5 × 10−5 L mol−1. The arrow shows the emission intensity changes upon increasing DNA concentration (left).
Plots of [DNA]/(εa – εf) vs. [DNA] for the titration complex with CT-DNA (right).
conclude that the nitrate salt of the title Mn(II) com- sured using an excitation wavelength of 520 nm. The
plex most possibly binds to DNA in an intercalation emission range was set between 550 and 750 nm. The
mode.
Considering these experimental results, we specu- Volmer equation [34, 38]:
late that the charge transfer of the ligand, caused by the
spectra were analyzed according to the classical Stern-
coordination of the central Mn(II) atom, results in re- Io/I = I +Ksv[Q]
duction of the charge density of the planar conjugated
system. Therefore, the complex should bind to DNA where I0 and I are the fluorescence intensities at
more easily [33]. In addition, owing to the presence 599 nm in the absence and presence of the quencher,
of an electron deficient center in the charged Mn(II) respectively, Ksv is the linear Stern-Volmer quenching
nitrate complex, an additional interaction between the constant, and [Q] is the concentration of the Mn(II)
complex and the phosphate-rich DNA backbone may complex. The fluorescence quenching of EB bound to
be envisaged [34, 35].
CT-DNA by the complex is shown in Fig. 3.
In general, measurements of the ability of a complex
to affect the intensity of an EB fluorescence in the EB-
DNA adduct allow the determination of the affinity of
Fluorescence spectra
No luminescence was observed for the complex the complex for DNA, whatever the binding mode may
at room temperature in aqueous solution, in any or- be. If a complex can displace EB from DNA, the flu-
ganic solvent examined, or in the presence of calf thy- orescence of the solution will be reduced due to the
mus (CT-DNA). So the binding of the complex cannot fact that free EB molecules are readily quenched by
be directly observed in the emission spectra. The en- the solvent water [39]. For the nitrate salt of the Mn(II)
hanced fluorescence of Ethidium bromide (EB) in the complex, no emission was observed either alone or
presence of DNA can be quenched by the addition of in the presence of CT-DNA in the buffer. The agree-
a second molecule [36, 37]. To further clarify the inter- ment with the Stern-Volmer equation provides fur-
action of the complex with DNA, a competitive bind- ther evidence that the compound binds to DNA. The
ing experiment was carried out in a buffer by keeping Ksv value for the Mn(II) nitrate complex is 1.88 ×
[DNA]/[EB] = 1 and varying the concentrations of the 104 L mol−1 (R = 0.9935 for 16 points in the line
complex. The fluorescence spectra of EB were mea- part).
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824
H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
Fig. 3. Emission spectra of EB bound to CT-DNA in the presence of the complex (left). [Complex] = 3 × 10−5 L mol−1
[complex] ×105 (right).
;
λ
ex = 520 nm. The arrows show the intensity changes upon increasing the concentration of the complex (left). Plot I0/I vs.
Viscosity measurements
Hydrodynamic measurements that are sensitive to
changes in DNA length are regarded as the least am-
biguous and most critical tests of a binding model in
solution in the absence of crystallographic structural
data [40, 41]. In classical intercalation, the DNA he-
lix lengthens as base pairs are separated to accommo-
date the bound complex, leading to increased DNA
viscosity, whereas a partial, non-classical complex in-
tercalation causes a bend (or kink) of the DNA helix
and reduces its effective length and thereby its viscos-
ity [42]. Viscosity experiments were conducted with
an Ubbelohde viscometer, immersed in a water bath
maintained at 25.0 ± 0.1 ◦C. Titrations were performed
for the complex (3 – 30 µM), the compound being in-
troduced into the CT-DNA solution (42.5 µM) present
in the viscometer. Data were analyzed as (η/η0)1/3
Fig. 4. Effect of increasing amounts of the complex on the
relative viscosity of CT-DNA at 25.0 ± 0.1 ◦C.
vs. the ratio of the concentration of the compound to the complex can intercalate with CT-DNA [44]. The re-
CT-DNA, where η is the viscosity of CT-DNA in the sults of the viscosity experiments confirm the mode of
presence of the compound and η0 is the viscosity of Mn(II) complex intercalation into DNA base pairs al-
CT-DNA alone. Viscosity values were calculated from ready established through absorption and fluorescence
the observed flow time of CT-DNA-containing solu- spectral studies.
tions corrected for the flow time of buffer alone (t0),
η = (t −t0) [43].
Antioxidant activity
The effect of the Mn(II) complex on the viscosity
of CT-DNA are shown in Fig. 4. The viscosity of CT-
Hydroxyl radicals were generated in aqueous media
DNA increased steadily with increasing amounts of the through the Fenton-type reaction [13, 45]. The reaction
nitrate salt Mn(II) complex. It is further illustrated that mixture (3 mL) contained 1.0 mL of 0.10 mmol aque-
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H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
825
using the same method as reported in a previous pa-
per [47]. The 50% inhibitory concentration (IC50) val-
ues of mannitol and vitamin C are about 9.6×10−3 and
8.7×10−3
M
−1, respectively. According to the antiox-
idant experiments, the IC50 values of the nitrate salt of
the Mn(II) complex is 2.11×10−6
M
−1 (Fig. 5), which
implies that the complex exhibits better scavenging ac-
tivity than mannitol and vitamin C.
Conclusions
In previous work we reported on the mono-
cationic
seven-coordinate
Mn(II)
complex
[Mn(Mentb)(salicylate)DMF]+ as its perchlorate
containing tris(2-(N-methyl)benzimidazolylmethyl)
amine, salicylate and DMF as ligands. Based on that
work, the same Mn(II) complex was synthesized as
nitrate, and the binding modes of the Mn(II) complex
with CT-DNA were studied. Especially photophysical
and viscosity measurements indicated that the Mn(II)
complex interacts with CT-DNA through intercalative
binding, which may be due to charge transfer and
reduction of the charge density of the planar conju-
gated system upon coordination to the metal complex.
The hydroxyl radical scavenging potential of the
complex was also investigated, and the results show
that the Mn(II) complex exhibits effective scavenging
properties. These findings indicate that the Mn(II)
complex has many potential practical applications for
the development of nucleic acid molecular probes and
new therapeutic reagents for diseases on the molecular
level and warrants further in vivo experiments and
pharmacological assays.
Fig. 5. The inhibitory effect of the complex on OH· radicals;
the suppression ratio increases with the concentration of the
test complex.
ous safranin, 1 mL of 1.0 mmol aqueous EDTA-Fe(II),
1 mL of 3% aqueous H2O2, and a series of quantita-
tive microadditions of solutions of the test compound.
A sample without the tested compound was used as the
control. The reaction mixtures were incubated at 37 ◦C
for 30 min in a water bath. The absorbance was then
measured at 520 nm. All the tests were run in triplicate
and are expressed as the mean and standard deviation
(SD) [46]. The scavenging effect for OH· radical was
calculated from the following expression:
Scavenging ratio (%) = [(Ai −A0)/(Ac −A0)]×100
where Ai = absorbance in the presence of the test com-
pound, A0 = absorbance of the blank in the absence of
the test compound, Ac = absorbance in the absence of
the test compound, EDTA-Fe(II) and H2O2.
We compared the ability of the present compound
to scavenge hydroxyl radicals with those of the well-
Acknowledgement
The authors acknowledge the financial support and a grant
from ‘Qing Lan’ Talent Engineering Funds by Lanzhou Jiao-
tong University. A grant from ‘Long Yuan Qing Nian’ of
known natural antioxidants mannitol and vitamin C, Gansu Province also is acknowledged.
[1] V. S. Li, D. Choi, Z. Wang, L. S. Jimenez, M. S. Tang,
H. Kohn, J. Am. Chem. Soc. 1996, 18, 2326 – 2331.
[2] G. Zuber, J. C. Quada, Jr., S. M. Hecht, J. Am. Chem.
Soc. 1998, 120, 9368 – 9369.
[6] K. Wieghardt, Angew. Chem., Int. Ed. Engl. 1989, 28,
1153 – 1172.
[7] V. L. Pecoraro, M. J. Baldwin, A. Gelasco, Chem. Rev.
1994, 94, 807 – 826.
[3] J. K. Barton, Science 1986, 233, 727 – 734.
[4] K. E. Erkkila, D. T. Odom, J. K. Barton, Chem. Rev.
1999, 99, 2777 – 2795.
[8] R. J. Sundberg, R. B. Martin, Chem. Rev. 1974, 74,
471 – 517.
[9] D. S. Pilch, Z. Xu, Q. Sun, E. J. Lavoie, L. F. Liu,
N. E. Geacintov, K. J. Breslauer, Drug Des. Discov.
1996, 13, 115 – 133.
[5] V. L. Pecoraro (Ed.), Manganese Redox Enzymes, VCH
Publishers, New York 1992.
Unauthenticated
Download Date | 1/2/19 11:09 AM

826
H. Wu et al. · Synthesis and DNA-binding Properties of a Cationic Seven-coordinate Manganese(II) Complex
[10] B. Willis, D. P. Arya, Biochem. 2010, 49, 452 – 469.
[11] H. L. Wu, Y. Bai, X. C. Huang, X. Meng. B. L. Qi, Acta
Crystallogr. 2010, E66, m1252.
[28] M. S. Lah, H. Chun, Inorg. Chem. 1997, 36,
1782 – 1785.
[29] H. L. Wu, Y. C. Gao, Trans. Met. Chem. 2004, 29,
175 – 179.
[12] H. L. Wu, F. Jia, X. Meng, Q. Chen, B. Liu, Y. L. Lai.
F. Kou, J. Coord. Chem. 2010, 63, 3627 – 3634.
[30] Z. X. Su, Y. Q. Wan, H. L. Wu, Synth. React. Inorg.
Met. Org. Nano. Met. Chem. 2005, 35, 553 – 558.
[31] K. Byunghoon, W. C. Ki, P. Myungho, S. L. Myoung,
Inorg. Chim. Acta 1999, 290, 21 – 27.
[13] S. Satyanaryana,
Biochem. 1993, 32, 2573 – 2584.
[14] J. Marmur, J. Mol. Biol. 1961, 3, 208 – 218.
J. C. Dabrowiak,
J. B. Chaires,
[15] H. M. J. Hendriks, P. J. M. W. L. Birker, G. C. Ver- [32] J. K. Barton, A. Danishefsky, J. Goldberg, J. Am. Chem.
schoor, J. Reedijk, J. Chem. Soc., Dalton. Trans. 1982,
623 – 631.
[16] W. K. Dong, Y. X, Sun, C. Y. Zhao, X. Y. Dong, L. Xu,
Soc. 1984, 106, 2172 – 2176.
[33] H. L. Wu, F. Kou, F. Jia, B. Liu, J. K. Yuan, Y. Bai, J.
Photochem. Photobiol. B 2011, 105, 190 – 197.
[34] A. Wolfe, G. H. Shimer, Jr., T. Meehan, Biochem. 1987,
26, 6392 – 6396.
[35] J. Liu, T. X. Zhang, L. N. Ji, J. Inorg. Biochem. 2002,
91, 269 – 276.
[36] A. M. Pyle, J. P. Rehmann, R. Meshoyrer, C. V. Kumar,
N. J. Turro, J. K. Barton, J. Am. Chem. Soc. 1989, 111,
3051 – 3058.
[37] S. Yellappa, J. Seetharamappa, L. M. Rogers, R. Chitta,
R. P. Singhal, F. D’Souza, Bioconjugate Chem. 2006,
17, 1418 – 1425.
Polyhedron 2010, 29, 2087 – 2097.
[17] W. K. Dong, C. Y. Zhao, Y. X. Sun, X. L. Tang, X. N.
He, Inorg. Chem. Commun. 2009, 12, 234 – 236.
[18] SAINT, Bruker Analytical X-ray Instruments Inc.,
Madison, Wisconsin (USA) 2000.
[19] G. M. Sheldrick, SADABS, Program for Empirical Ab-
sorption Correction of Area Detector Data, University
of Go¨ttingen, Go¨ttingen (Germany) 2004.
[20] G. M. Sheldrick, SHELXTL, Siemens Analytical X-
ray Instruments Inc., Madison, Wisconsin (USA) 1996.
See also: G. M. Sheldrick, Acta Crystallogr. 2008, A64, [38] M. Shakir, M. Azam, M.-F. Ullah, S.-M. Hadi, J. Pho-
112 – 122. tochem. Photobiol. B. 2011, 104, 449 – 456.
[21] C. Y. Su, B. S. Kang, C. X. Du, Q. C. Yang, T. C. W. [39] B. C. Baguley, M. Le Bret, Biochem. 1984, 23,
Mak, Inorg. Chem. 2000, 39, 4843 – 4849. 937 – 943.
[22] T. J. Lane, I. Nakagawa, J. L. Walter, A. J. Kandathil, [40] J. R. Lakowicz, G. Webber, Biochem. 1973, 12,
Inorg. Chem. 1962, 1, 267 – 276. 4161 – 4170.
[23] A. W. Addison, H. M. J. Hendriks, J. Reedijk, L. K. [41] M. Chauhan, K. Banerjee, F. Arjmand, Inorg. Chem.
Thompson, Inorg. Chem. 1981, 20, 103 – 110. 2007, 46, 3072 – 3082.
[24] P. P. Hankare, S. R. Naravane, V. M. Bhuse, S. D. [42] J. B. LePecq, C. Paoletti, J. Mol. Biol. 1967, 27,
Deleker, A. H. Jaytap, Indian J. Chem. 2004, 43,
1464 – 1467.
87 – 106.
[43] M. Sethuraman, P. Mallayan, Inorg. Chem. 1998, 37,
[25] K. Nakamoto, Infrared and Raman Spectra of Inor-
693 – 700.
ganic and Coordination Compounds, Vol. 3, John [44] A. B. Tossi, J. M. Kelly, Photochem. Photobiol. 1989,
Wiley and Sons, Academic Press, New York, 1978,
pp. 200 – 201.
49, 545 – 556.
[45] C. P. Tan, J. Liu, L. M. Chen, S. Shi, L. N. Ji, J. Inorg.
[26] J. Catterick, P. Thornton, Adv. Inorg. Chem. 1977, 20,
291 – 362.
[27] S. Musumeci, E. Rizzarelli, S. Sammartano, A. Sem-
inaba, Z. Anorg. Allg. Chem. 1977, 433, 297 – 304.
Biochem. 2008, 102, 1644 – 1653.
[46] S. Satyanarayana, J. C. Dabrowiak, J. B. Chaires,
Biochem. 1992, 31, 9319 – 9324.
[47] T. R. Li, Z. Y. Yang, B. D. Wang, D. D. Qin, Eur. J.
Med. Chem. 2008, 43, 1688 – 1695.
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