Portraying the role of halo ligands and the auxiliary part of ligands of mononuclear manganese(iii)-Schiff base complexes in catalyzing phospho-ester bond hydrolysis

Article abstract of DOI:10.1039/c8nj02634c

Four mononucleating Schiff base ligands, namely HL1, HL2, HL3 and HL4, were prepared via condensation between 2-hydroxybenzaldehyde and 2-morpholinoethanamine, 2-(piperazin-1-yl)ethanamine, 2-(piperidin-1-yl)ethanamine and 2-(pyrrolidin-1-yl)ethanamine, r

Full text of DOI:10.1039/c8nj02634c

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PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
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Portraying the Role of Halo Ligands and Auxiliary Part of Ligands of
Mononuclear Manganese(III)-Schiff Base Complexes on Catalyzing
Phospho-ester Bond Hydrolysis
TonmoyChakraborty,aSanchariDasgupta,aEnnioZangrando*,b and Debasis Das*,a
aDepartment of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata 700009, India.
b
Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via L.
Giorgieri 1, 34127 Trieste, Italy.
Abstract:
Four mononucleating Schiff base ligands, namely HL1, HL2, HL3 and HL4,were prepared
via condensation between 2-hydroxybenzaldehyde and 2-morpholinoethanamine, 2-
(piperazin-1-yl)ethanamine, 2-(piperidin-1-yl)ethanamine and 2-(pyrrolidin-1-yl)ethanamine,
respectively. Then seven mononuclear manganese (III) complexes were synthesized using the
indicated ligands. Complexes 1-3 were prepared with ligand HL1 by using chloride, bromide
and iodide salts of manganese(II), respectively. On the other hand complexes 4, 5, 6 and 7
were prepared by reaction of manganese chloride followed by sodium thiocyanate with
ligands HL2, HL3, HL4, and HL1, respectively. All the complexes were characterized by
usual physicochemical techniques and their solid state structures were obtained from single
crystal X-Ray analysis. The phosphatase like activity of these complexes was studied in 97.5
% (v/v) N, N- dimethylformamide - water mixture using disodium salt of 4-
nitrophenylphosphate (4-NPP) as model substrate to evaluate the role of halo-anions and
auxiliary part of ligand backbone towards phosphatase like activity. Detailed experimental
findings proved that complex 2 is the most active catalyst among all seven complexes and the
complex bearing the morpholine ring is the highest active catalyst among complexes 4-7.
Introduction
Phosphatases are a group of hydrolysis enzymes containingtransition and post transition
metal ion(s) in their active sites. These enzymes catalyze the hydrolysis of phosphate-ester
(P-O) bond ofmono-, di-, tri-esters, fluorophosphates, fluorophosphonates, phosphoric
anhydrides and many other such kind of enzymes.1-12 The study of these enzymes is not only
related to biochemical processes such as DNA fragmentation, RNA replication, bone
metabolism, but also to application in medical field (use in chemotherapy, development of
1

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foot printing reagents etc.) and in agriculture (removal of phosphate containing pesticides).13-
16
Among transition metals, zinc(II) metal ion, having the highest Lewis acidity among the
divalent metal ions, is the obvious choice of nature in most of the active site of phosphatase
enzymes.17-19 But a number of purple acid phosphatase enzymes contain iron(III) and
insignificant amount of manganese(III) in their active sites. These phosphatases are mainly
isolated from plants and mammalian sources such as beef spleen and uterine fluid etc.20 Metal
ions play a major role in phosphate ester bond cleavage by influencing the following factors:
(i) stabilization of the transition-state by metal ion coordination, hydrogen-bonding or proton-
transfer, (ii) formation of metal coordinated hydroxide thatacts as a nucleophile, (iii)
stabilization of hydrolyzed product, (iv) formation of product and regeneration of
catalyst.21For more than 40 years, preparation of structural models as well as functional
models of phosphatase enzymes has been drawn great attention by bio-inorganic chemists.22
It has been already established that coordination of phosphate ester to dinuclear model
complexes increases the rate with respect to mononuclear mimicking models.23 The other
basic factors influencing the rate of phosphatase activity of model complexes are reaction
conditions, metal centres, stereochemistry and coordination environment of metal ions, ligand
backbone.24-26With the help of theoretical and experimental studies,our group has recently
established the role of coordination environment of metal ions,27 halo-ligands,28 para-
substituents in phenol based ligand systems29 and presence of electronegative atom on ligand
backbone30 using zinc(II) and nickel(II) based functional models. Herein, we report seven
mononuclear manganese(III)-Schiff base complexes (Fig. 1) with the aim to explore their
phosphatase activity using di-sodium salt of 4-nitrophenylphosphate (4-NPP) as model
substrate.Complexes 1-3 were prepared using altered manganese(II) halide salts as precursor
to unveil the effect of halo ligands on the phosphatase activity of these manganese(III) model
systems. Complexes 4-7 were synthesised from a class of Schiff base ligands bearing a
different hetero ring in their molecular structure with the purpose to explore the role of the
‘auxiliary part of ligand’31 on the phosphatase activity. Detailed experimental results prove
that out of seven manganese(III) complexes, complex 2 shows the highest activity and among
complexes 4-7 the highest activity is displayed by the latter with ligand bearing a morpholine
moiety (presence of oxygen as heteroatom).
2

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Fig.1 Synthetic route of Complexes 1-7
Experimental section
Materials and physical methods
All reagents and chemicals were purchased from Sigma and used without further purification.
Solvents used for spectroscopic studies were purified and dried by standard procedures before
use. UV-Vis spectra were recorded on SHIMADZU UV-2450 spectrophotometer. Solvent N,
N-dimethylformamide (DMF) used for UV-Vis study was of spectroscopy grade. The
concentration of solutions used for UV-Vis studies was kept in the range of ~5×10-3 (M) in
order to avoid precipitation. Samples for FT-IR study were prepared as KBr pellets, and
spectra were obtained in the 400-4000 cm-1 range using a Perkin-Elmer 1600 FTIR
spectrometer. Elemental analyses were performed on a Perkin-Elmer Model 2400 analyzer.
The Electrospray mass spectra were recorded on a XEVO G2 SQ-TOF mass spectrometer. 2-
Hydroxybenzaldehyde, 2-morpholinoethanamine, 2-(piperazin-1-yl) ethanamine, 2-
(piperidin-1-yl) ethanamine, 2-(pyrrolidin-1-yl) ethanamine, (4-nitrophenyl) phosphate
(Sigma-Aldrich) were purchased from commercial source and used as received. All the
solvents were distilled prior to use.
Synthesis of [Mn (L1)2(H2O) Cl].H2O (1)
A methanolic solution (5 ml) of 2-morpholinoethanamine (0.260g, 2mmol) was added
dropwise to a methanolic solution (10 ml) of 2-hydroxybenzaldehyde (0.244g, 2 mmol) and
.
the resulting mixture was refluxed for 2 hours. Then a methanolic solution of MnCl2 3H2O
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(0.450g, 2.5mmol) was added and the resulting mixture was stirred for 6 hours. After
filtration the clear deep brown solution was kept in a CaCl2 desiccator. After few days needle
shaped brown crystals suitable for X-ray diffraction were obtained. Yield: 79%; Anal. Calcd.
for C26H40Cl1Mn1N4O7: C (51.11%); H (6.60%); N (9.17%); Found: C (51.02%); H (6.03%);
N (9.228%); FT-IR (KBr pellet):
UV/Vis (DMF): λmax
) = 368.19 nm (4000 L mol−1 cm−1), 316.40 nm (8980 L mol−1 cm−1),
ν ν
(C=N) 1617cm−1; (skeletal vibration) 1541 cm−1(Fig. S1);
(ε
264.93 nm (14000 L mol−1 cm−1) (Fig. S8).
Synthesis of [Mn (L1)2(H2O)2].Br (2)
Complex 2 was synthesized following the same procedure adopted for complex 1.
.
MnBr2 3H2O (0.536 g, 2 mmol) was used instead of chloride salt. After a few days, brown
block shaped crystals suitable for XRD analyses were obtained. Yield: 83%; Anal. Calcd. for
C26H38Br1Mn1N4O6: C (48.99%); H (6.01%); N (8.79%); Found: C (48.174%); H (6.335%);
N (8.992%); FT-IR (KBr pellet):
UV/Vis (DMF): λmax
) = 372.19 nm (1490L mol−1 cm−1), 315.39 nm (2440L mol−1 cm−1),
ν ν
(C=N) 1632cm−1; (skeletal vibration) 1566 cm−1(Fig. S2);
(ε
265.93 nm (4160 L mol−1 cm−1) (Fig. S8).
Synthesis of [Mn (L1)2(CH3OH)2].(I3)(3)
.
Complex 3 was synthesized by following same procedure as for complex 1 using MnI2 3H2O
.
(0.905 g, 2.5 mmol) instead of MnCl2 3H2O. After a few days, brown needle shaped crystals
suitable for XRD analyses were obtained. Yield: 78%; Anal. Calcd. for C28H42(I3)1Mn1N4O6:
C (34.80%); H (4.38%);N (5.80%); Found: C (34.34%); H (4.9%); N (5.09%); FT-IR (KBr
(C=N) 1617cm−1; (skeletal vibration) 1549 cm−1(Fig. S3); UV/Vis (DMF): λmax
pellet): ν ν (ε)
= 367.72 nm (2540 L mol−1 cm−1), 294.82 nm (5160 L mol−1 cm−1), 265.16 nm (4460 L mol−1
cm−1) (Fig. S8).
Synthesis of [Mn (HL2)2(SCN)2][Mn(HL2)2(Cl)(SCN)](SCN)1.63.Cl0.37.H2O(4)
A methanolic solution (5 ml) of 2-(piperazin-1-yl)ethanamine (0.130 g, 1mmol) was added
dropwise to a methanolic solution (10 ml) of 2-hydroxybenzaldehyde (0.122 g, 1mmol) and
.
the resulting mixture was refluxed for 2 hours. A methanolic solution of MnCl2 3H2O (0.179
g, 1mmol) was added and stirred for 30 min, and then an aqueous solution of NaSCN (0.162
g, 2 mmol) was added to the reaction mixture and stirred for an hour. After a few days, brown
cube shaped crystals suitable for XRD analyses were obtained. Yield: 78%; Anal. Calcd. for
C57H76Cl1Mn2N17O5S5: C (43.42%); H (5.06%); N (12.51%); Found: C (43.158%); H
(5.434%); N (12.123%); FT-IR (KBr pellet):
ν
(C=N) 1614cm−1;
) = 372.19 nm (714 L mol−1 cm−1),
ν(skeletal vibration) 1541
cm−1, (SCN) 2059 cm−1(Fig. S4); UV/Vis (DMF): λmax
ν
(ε
315.39 nm (6480 L mol−1 cm−1), 265.93 nm (4000 L mol−1 cm−1) (Fig. S8).
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Synthesis of [Mn (HL3)2(SCN)2](SCN).H2O(5)
A methanolic solution (5 ml) of 2-(piperidin-1-yl)ethanamine (0.130 g, 1mmol) was added
dropwise to a methanolic solution (10 ml) of 2-hydroxybenzaldehyde (0.122 g,1mmol) and
.
the resulting mixture was refluxed for 2 hours. A methanolic solution of MnCl2 3H2O (0.179
g, 1mmol) was added and stirred for 30 min; then a water solution of NaSCN (0.162g, 2
mmol) was added to the reaction mixture and stirred for an hour. After a few days, brown
needle shaped crystals suitable for XRD were obtained. Yield: 82%; Anal. Calcd. for
C31H42Mn1N7O3S3: C (52.31%); H (5.95%); N (13.77%); Found: C (52.08%); H (5.50%); N
(13.56%); FT-IR (KBr pellet):
ν
(C=N) 1612 cm−1;
ν ν(SCN)
(skeletal vibration) 1539 cm−1,
2059 cm−1(Fig. S5); UV/Vis (DMF): λmax
(ε
)= 376.18 nm (1440L mol−1 cm−1), 318.89 nm
(5640 L mol−1 cm−1), 263.37 nm (16120L mol−1 cm−1) (Fig. S8).
Synthesis of [Mn (HL4)2(SCN)2](SCN).H2O(6)
A methanolic solution (5 ml) of 2-(pyrrolidin-1-yl)ethanamine (0.130 g, 1mmol) was added
dropwise to a methanolic solution (10 ml) of 2-hydroxybenzaldehyde (0.122 g,1mmol) and
the resulting mixture was refluxed for 2 hours. Then a methanolic solution of MnCl2.3H2O
(0.179 g, 1mmol) was added and stirred for 30 min, followed by a water solution of
NaSCN(0.162 g, 2 mmol) and the reaction mixture was stirred for an hour. After a few days,
brown block shaped crystals suitable for XRD analyses were obtained. Yield: 79%; Anal.
Calcd for C29H38Mn1N7O3S3: C (50.94%); H (5.60%); N (14.34%); Found: C (55.08%); H
(5.50%); N (13.56%); FT-IR (KBr pellet):
ν
(C=N) 1620cm−1;
)= 373.40 nm (2040L mol−1 cm−1),
ν(skeletal vibration) 1552
cm−1, (SCN) 2056cm−1(Fig. S6); UV/Vis (DMF): λmax
ν
(ε
316.17 nm (12040L mol−1 cm−1), 265.70 nm (15660 L mol−1 cm−1) (Fig. S8).
Synthesis of [Mn (HL1)2(SCN) (H2O)].H2O (7)
A methanolic solution (5 ml) of 2-morpholinoethanamine (0.260 g, 2 mmol) was added
dropwise to a methanolic solution (10 ml) of 2-hydroxybenzaldehyde (0.122 g, 1mmol) and
the resulting mixture was refluxed for 2 hours. Then a methanolic solution of MnCl2.3H2O
(0.179 g, 1mmol) was added and stirred for 30 min, followed by aqueous solution of NaSCN
(2 mmol, 0.162g) and stirring was continued for an hour. After a few days, brown needle
shaped crystals suitable for XRD analyses were obtained. Yield: 85%; Anal. Calcd. for
C27H38Mn1N5O6S1: C (52.68%); H (6.22%); N (11.38%); Found: C (52.08%); H (6.50%); N
(11.56%); FT-IR (KBr pellet) :
ν
(C=N) 1620 cm−1;
ν ν(SCN)
(skeletal vibration) 1552 cm−1,
2056 cm−1(Fig. S7); UV/Vis (DMF): λmax
(ε
)= 373.40 nm (2040 L mol−1 cm−1), 316.17 nm
(12040 L mol−1 cm−1), 265.70 nm (15660 L mol−1 cm−1) (Fig. S8).
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X-ray Crystallographic data collection and refinement
Intensities data for crystal structure analyses of compounds 2-7 were collected on a Bruker
Smart Apex diffractometer equipped with CCD. In all cases measurements were conducted at
room temperature with Mo-Kα radiation (λ = 0.71073 Å). Cell refinement, indexing, and
scaling of the data sets were done using the programs Bruker Smart Apex, and Bruker Saint
packages.32 Experiment of compound 1 was performed at 100 K at the Elettra Synchrotron
(Trieste, Italy), with amonochromatic wavelength of 0.700 Å. The diffraction data were
indexed, integrated and scaled using XDS33All the structures were solved by direct methods
and subsequent Fourier analyses34 and refined by the full-matrix least-squares method based
on F2 with all observed reflections.34 In compound 4, one of the two independent complexes
shows the axial ligands disordered, being occupied by a chloride and SCN with occupancy of
0.56/0.44, respectively with the metal located on a centre of symmetry. Associated to the
chloro ligand the Fourier map evidenced a methanol molecule (occupancy of 0.56). In
addition the counter anion SCN in 4 is disordered over two positions (occupancy of
0.72/0.28). Hydrogen atoms, included in final cycles of refinement, were placed at calculated
positions (with exception of protonated NH groups of Schiff base ligands in 6 which were
located in the Fourier map) and those of water molecules. All calculations were performed
using the WinGX System, Ver2013.03.35 Crystal data and details of refinements are given in
Table S1 and S2.
Kinetic measurements of the Hydrolysis of 4-NPP in 97.5% (v/v) DMF-H2O
The reaction was followed by UV-Vis spectroscopy by using disodium (4-nitrophenyl)
phosphate (4-NPP) hexahydrate as model substrate. The course of the catalytic reaction was
monitored by the increment of the absorption band at λmax= 427 nm in presence of complexes
1-7 due to the hydrolyzed product of 4-NPP, i.e. 4-nitrophenolate ion (ε
=18500 M-1cm-1) in
aqueous DMF at 25°C. Initially, a series of solutions of substrate 4-NPP, having different
concentrations (from1×10-3 to 5×10-2mol dm3), was prepared from a concentrated stock
solution using DMF-H2O 97.5% (v/v)as solvent. Then 3 ml of the substrate solution was
poured into a 1 cm quartz cell kept in the spectrophotometer to equilibrate the temperature at
25°C, and 0.03 ml 5×10-3M of MnIII complex in DMF were quickly added and mixed
thoroughly. The final A∞ values for each set were obtained after one day. The determination
of the initial rates, as function of the concentration of 4-NPP, reveals saturation kinetics with
Michaelis-Menten like behaviour. The kinetic parameters (kcat, Vmax, kM) for the hydrolysis of
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phosphate-ester bond were determined using non-linear least square method and Michaelis-
Menten approach of enzyme kinetics was followed.
Results and discussion
Synthesis of ligands and complexes
All the complexes (1-7) were prepared by adopting template synthesis method; complexes 1-
3 were prepared using manganese(II) chloride/bromide/iodide salts added to the Schiff-base
ligand HL1, prepared in situ via condensation of 2-hydroxybenzaldehyde and 2-
morpholinoethanamine.On the other hand complexes 4-6 were prepared using manganese(II)
chloride followed by the addition of aqueous solution of sodium thiocyanate to the Schiff-
base ligands HL2, HL3 and HL4 respectively, synthesized in situ via condensation of 2-
hydroxybenzaldehydewith2-(piperazin-1-yl)ethanamine,2-(piperidin-1-yl)ethanamine, and 2-
(pyrrolidin-1-yl)ethanamine, respectively.
FT-IR and UV-Vis spectra of the Complexes
All the complexes were initially characterised by FT-IR spectroscopy. For all the complexes
FT-IR band was observed at around 1610-1635 cm-1due to the presence of C=N stretching
and the bands signature of skeleton vibrations are present in the region of 1535-1566 cm−1.
For complexes 4,5,6,7 an additional band for the SCN- ion coordinated to the metal centre,
appears at around 2055-2060 cm-1, and the observed split band is probably due to the
presence of coordinated as well as free SCN− ions,as confirmed by single crystal X-ray
analysis (vide infra). FT-IR spectra of complexes 1-7 are presented in Supporting
Information(Fig. S1-S7).
The electronic spectra of complexes 1-7 were recorded in DMF medium (Fig.S8) showing
absorption bands at λmax ~ 371 nm due to charge-transfer transitions from their plane p
orbital of phenolate to the half-filled d * orbital of manganese(III), and higher energy bands
near 315 nm due to
* transitions involving the phenolate moieties of the complexes.36
Electrospray Ionization Mass Spectral study
π
π
π-π
The electrospray ionization mass (ESI-MS positive) spectra of complexes 1-7 were recorded
in acetonitrile solution to access their composition in solution phase. All complexes showed
monopositive species in solution. For complexes 1, 2, 3, 7 the base peak at m/z = 521.202
+
amu (calcd. m/z = 521.1960 amu) is consistent with a molecular formula of C26H34MnN4O4 .
The base peak for complex 4 appears at m/z =259.0234 amu (calcd. m/z =259.614amu)
consistent with a molecular formula of C26H36MnN6O22+ and for complexes 5 and 6 the peaks
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at m/z = 517.2513 amu (calcd. m/z = 517.2375 amu) and 489.2091 amu (calcd. m/z
=
489.2062 amu) are the most abundant in agreement with molecular formula of
+
+
C28H38MnN4O2 and C28H36MnN2O2 , respectively. The ESI-MS spectra of complexes 1-7 are
given in S.I file (Fig. S9-S15)
X-ray crystal structure determination
In all the structurally characterized complexes two Schiff base ligands coordinate the
manganese atom in the equatorial positions of the octahedral environment by chelating the
metal through the phenol oxygen and the imino nitrogen donors in trans configuration. Thus
the appended heterocycles of chelating ligands, namely morpholine (in 1, 2, 3 and 7),
piperazine (4), piperidine (5) and pyrrolidine (6) are far apart from the metal centre and result
not coordinating.
In complex 1 the Cl-Mn-OH2 axial fragment, which completes the octahedral coordination
geometry, is positioned on a two-fold axis. On the other hand in 2 and 3 the manganese atom
is located on a crystallographic inversion centre completing the coordination sphere through
two symmetry related aquo ligands in 2 and methanol molecules in 3. Ortep drawings of
these complexes are shown in Figs.2-4, and a selection of bond lengths and angles is reported
in Table 1. The geometrical data for these complexes show close comparable Mn-
O(phenoxo) and Mn-N(1) bond lengths falling in the range 1.864(3)-1.8757(12) Å, and
2.036(4) - 2.0490(14) Å, respectively and bond angles of coordination geometry close to
ideal values. The axial distances in 1 are significantly longer, Mn-O(1w) of 2.236(3)Å and
Mn-Cl(1) of 2.6038(13)Å, as well as the two symmetry related bond lengths Mn-O(1w) in 2
and Mn-O(methanol) in 3 that are of 2.2038(13) and 2.256(4) Å, respectively. For these
halide complexes only the chloride is bound to the metal in 1, while in 2 and 3 the bromide
−
and iodide (as I3 ) act as counter anions and do not participate in coordination.
In each case the crystal packing is affected by the formation of H-bonds involving the water
molecules (Table 5). In complex 1 the water ligand O(1w) is bound to the lattice water
molecule O(2w)(O…O distance of 2.719(4) Å), and in turn O(2w) act as donors towards N(2)
andCl(1) of symmetry related complexes (O(2w)…N(2) = 2.781(4) Å; O(2w)…Cl(1) =
3.216(3) Å) to form a 2D supramolecular arrangement (Fig. S16). The complex structure of 2
is reinforced by an intra H-bond between the aquo O(1w)and the morpholine nitrogen
(Ow…N(2) = 2.7075(19) Å) and in addition is connected to a bromide ion (Ow…Br(1) =
3.2829(14) Å) with formation of a polymeric chain (Fig. S17). In complex 3 the methanol
OH group forms a hydrogen bond with morpholine oxygen O(2) of a symmetry related
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complex (O(3)…O(2) = 2.684(6) Å) and vice versa to form dimeric complex species (Fig.
S18).
Fig. 2 ORTEP drawing (ellipsoid probability 35%) of complex 1 with atom labels of the
crystallographic independent unit.
Fig.3 ORTEP drawing (ellipsoid probability 35%) of complex cation 2 with indication of
intramolecular H-bond and of atom labels of the crystallographic independent unit.
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Fig.4 ORTEP drawing (ellipsoid probability 35%) of complex cation 3 with atom labels of
the crystallographic independent unit.
Table 1Selected coordination bond distances (Å) and angles (°) for complexes1-3.
1
2
3
Mn-O(1)
Mn-N(1)
Mn-O(1w)
Mn-Cl(1)
1.873(2)
2.043(3)
2.236(3)
2.6038(13)
Mn-O(1)
Mn-N(1)
Mn-O(1w)
1.8757(12) Mn-O(1)
2.0490(14) Mn-N(1)
2.2038(13) Mn-O(3)
1.864(3)
2.036(4)
2.256(4)
O(1)-Mn-N(1)
O(1)-Mn-N(1)#1 89.17(11) O(1)-Mn-N(1)#1
O(1)-Mn-O(1w) 85.37(8) O(1)-Mn-O(1w)
91.12(11) O(1)-Mn-N(1)
90.43(6)
89.57(6)
90.23(6)
O(1)-Mn-N(1)
O(1)-Mn-N(1)#1 89.76(15)
O(1)-Mn-O(3) 90.86(15)
90.24(15)
O(1)-Mn-O(1)#1 170.74(15) O(1)-Mn-O(1w)#1 89.77(6)
O(1)-Mn-O(3)#1 89.14(15)
N(1)-Mn-O(3)#1 91.58(14)
O(1)#1-Mn-O(3) 89.14(15)
N(1)#1-Mn-O(3) 91.58(14)
O(1)-Mn-Cl(1)
N(1)-Mn-O(1w)
94.63(8)
91.83(7)
N(1)-Mn-O(1w)#1 90.64(5)
O(1)#1-Mn-O(1w) 89.77(6)
N(1)-Mn-N(1)#1 176.35(14) N(1)#1-Mn-O(1w) 90.64(5)
N(1)-Mn-Cl(1) 88.17(7) N(1)-Mn-O(1w) 89.36(5)
O(1w)-Mn-Cl(1) 180.0
Symmetry codes: #1 = -x+1,y,-z+3/2 for 1; -x+1,-y,-z+1 for 2; -x+1,-y+2,-z+1 for 3.
N(1)-Mn-O(3)
88.42(14)
In complex 4 there are two independent complexes with the metal located on a centre of
symmetry, but in one case, a positional disorder is detected in the crystal, being the metal
Mn(1) bound to a chloride and thiocyanate anion of ca. half occupancy each. Associated to
this disordered derivative, the Fourier map shows a lattice methanol molecule in concurrence
with the presence of the chloride ligand, leading to
a
formulation of
.
[Mn(HL2)2(SCN)2][Mn(HL2)2(Cl)1.12(SCN)0.88](SCN)2 1.12(CH3OH). The two complex
cations are depicted in Fig.5, and a selection of bond distances and angles is reported in Table
2. The thiocyanate anions are bound to metal Mn(1) with a C-N-Mn angle of 148.7(13)°,
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while at Mn(2) are practically linearly coordinated (174.3(2)°). The Mn-N and Mn-O bond
distances of the chelating Schiff bases fall within the range found in 1-3. The axial distances
of Mn(1) are affected by the disorder (Mn(1)-N(4) = 2.415(16), Mn(1)-Cl(1) = 2.630(4) Å),
the former at low accuracy. On the other hand the Mn(2)-N(8) is of 2.258(2)Å. Here the
Schiff base ligands are neutral having the piperazine fragments protonated at piperazine
nitrogen and the complex cations are counterbalanced by lattice SCN anions. The protonated
+
piperazine NH2 groups are involved in H-bonds (Table 5) although some interactions
include disordered atoms.
Table 2 Selected coordination bond distances (Å) and angles (°) for the two independent
complex cations of4.
Mn(1)a
Mn(2)
Mn(1)-O(1)
Mn(1)-N(1)
Mn(1)-N(4)
Mn(1)-Cl(1)
1.8571(14)
2.0494(16)
2.415(16)
2.630(4)
Mn(2)-O(2)
Mn(2)-N(5)
Mn(2)-N(8)
-
1.8682(17)
2.0607(17)
2.258(2)
-
O(1)-Mn(1)-N(1)
O(1)-Mn(1)-N(1) '
O(1)-Mn(1)-N(4)
O(1)-Mn(1)-N(4) '
N(1)-Mn(1)-N(4) '
N(1)-Mn(1)-N(4)
C(14)-N(4)-Mn(1)
90.47(6)
89.52(6)
87.9(5)
92.1(5)
93.1(5)
86.9(5)
148.7(13)
O(2)-Mn(2)-N(5) ''
O(2)-Mn(2)-N(5)
O(2)-Mn(2)-N(8) ''
O(2)-Mn(2)-N(8)
N(5)-Mn(2)-N(8)
N(5)-Mn(2)-N(8) ''
C(15)-N(8)-Mn(2)
90.32(7)
89.68(7)
90.95(9)
89.05(9)
90.59(8)
89.41(8)
174.3(2)
Symmetry codes: (') -x+1,-y+1,-z+1; ('') -x+1,-y+1,-z+2.
a)Axial ligands at Mn(1) are disordered having a SCN and a Cl at ca. half occupancy (see
experimental section). Bond angles relative to Cl(1) not reported.
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Fig.5 ORTEP drawing (ellipsoid probability 35%) of the two independent complex cations of
compound 4, in the former ligands SCN and Cl (with associated MeOH molecule) are
disordered at the axial positions being Mn1 located on an inversion centre.
The diffraction analysis of complexes 5 and 6 shows similar independent units comprising
one complex cation, one lattice SCN anion and one water molecule. The Schiff base ligands
chelate the manganese atom at the equatorial positions with a trans arrangement as observed
in other complexes reported, and the coordination sphere is completed by two SCN anions
bound through nitrogen as shown in Fig.s 6 and 7. Due to the low accuracy of X-ray
diffraction data obtained for complex 5, we do not report and discuss data of this compound.
Coordination bond distances of 6 (Table 3) follow the trend previously observed in other
complexes with coordination bond angles close to the ideal octahedral values. The
thiocyanates in 6 are significantly bent upon coordination with C-N-Mn angles of 168.3(2)
and 144.6(2)°). It is worth of note the orientation of chelating Schiff bases, forming a
dihedral angle of ca. 30° in 5 and of 34.95° and 6, contrary to the almost coplanar orientation
detected in other complexes (Fig.8). The protonated N atoms of pyrrolidine and lattice water
molecule (in 6) form H-bonds with the SCN anions to form polymeric chains developed
along axis c (Table 4, Fig. S19).
Table 3 Coordination bonddistances (Å) and angles (°) for the complex cationof 6.
Mn-O(1)
Mn-O(2)
Mn-N(1)
1.8748(16)
1.8781(15)
2.0593(17)
Mn-N(3)
Mn-N(5)
Mn-N(6)
2.0403(17)
2.238(2)
2.281(2)
O(1)-Mn-O(2)
O(1)-Mn-N(1)
O(2)-Mn-N(1)
O(1)-Mn-N(3)
O(2)-Mn-N(3)
N(1)-Mn-N(3)
O(1)-Mn-N(6)
O(2)-Mn-N(6)
O(1)-Mn-N(5)
178.06(7)
90.52(7)
91.36(7)
88.65(7)
89.47(7)
179.16(7)
92.96(9)
86.67(8)
90.78(9)
O(2)-Mn-N(5)
N(1)-Mn-N(5)
N(3)-Mn-N(5)
N(1)-Mn-N(6)
N(3)-Mn-N(6)
N(5)-Mn-N(6)
C(15)-N(5)-Mn
C(16)-N(6)-Mn
89.71(8)
88.89(7)
91.08(7)
87.63(7)
92.45(7)
174.92(8)
168.3(2)
144.6(2)
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Fig.6 Molecular structure of complex cation 5.
Fig.7 ORTEP drawing (ellipsoid probability 35%) of complex cation 6.
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Fig.8 Perspective view of complexes 5 and 6, showing the mean planes through the Schiff
base ligands.
The crystallographic independent unit of complex 7 comprises one Mn complex and one
lattice water molecule, the molecular structure (Fig.9) being similar to that of 1, by
substituting the chloride with a SCN anion. The coordination bond distances and angles
(Table 4) reflect the trend observed in other complexes herein reported. The coordinated
water molecule O(1w) forms a weak hydrogen bond with water molecule O(2w), and both
water species act as H-acceptor with respect to the protonated morpholine nitrogen atoms
(O(1w)…N(4) = 2.839(3),O(2w)…N(3) 2.815(3) Å) to form a 1D chain in the crystal
packing (Fig. S20).
Table 4 Selected coordination distances (Å) and angles (°) for complex7.
Mn-O(1)
Mn-O(2)
Mn-N(1)
1.8616(17)
1.8708(17)
2.043(2)
Mn-N(2)
Mn-N(5)
Mn-O(1w)
2.047(2)
2.218(3)
2.320(2)
O(1)-Mn-O(2)
O(1)-Mn-N(1)
O(2)-Mn-N(1)
O(1)-Mn-N(2)
O(2)-Mn-N(2)
N(1)-Mn-N(2)
O(1)-Mn-N(5)
O(2)-Mn-N(5)
176.93(9)
90.65(8)
89.75(8)
89.70(8)
89.55(8)
173.30(8)
91.38(10)
91.64(9)
N(1)-Mn-N(5)
N(2)-Mn-N(5)
O(1)-Mn-O(1w)
O(2)-Mn-O(1w)
N(1)-Mn-O(1w)
N(2)-Mn-O(1w)
N(5)-Mn-O(1w)
C(14)-N(5)-Mn
93.07(9)
93.61(9)
89.56(8)
87.43(8)
86.82(8)
86.49(8)
179.06(9)
172.7(3)
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Fig.9 ORTEP drawing (ellipsoid probability 50%) of complex 7.
Table 5 Hydrogen bond parameters.
Complex 1
D-H
d(D-H)
0.69(6)
0.84(7)
0.87(6)
d(H..A)
2.08(6)
1.95(6)
2.37(6)
<DHA
156(6)
171(6)
164(6)
d(D..A)
2.719(4)
2.781(4)
3.216(3)
A
O2w
N2
Symmetry code of A
O1w-H11
O2w-H21
O2w-H22
1-x,1-y,1-z
x,1+y,z
Cl1
Complex 2
D-H
O1w-H11
O1w-H12
d(D-H)
0.85(2)
0.77(3)
d(H..A)
2.48(2)
1.95(3)
<DHA
158(2)
174(3)
d(D..A)
3.2829(14) Br1
2.7075(19) N2
A
Symmetry code of A
x,-1+y,z
Complex 3
D-H
O3-H20
d(D-H)
0.81(10)
d(H..A)
1.87(9)
<DHA
175(12)
d(D..A)
2.684(6)
A
O2
Symmetry code of A
2-x,1-y,1-z
Complex 4
D-H
N3-H3a
N3-H3b
N7-H7a
N7-H7b
d(D-H)
0.89
0.89
0.89
0.89
d(H..A)
1.89
2.24
2.78
1.86
<DHA
164
152
128
168
d(D..A)
2.752(8)
3.052(7)
3.400(5)
2.739(7)
A
Symmetry code of A
-1+x,y,z
-1+x,y,z
N9
Cl1 a
S3a
1-x,-y,-z
O1w a x,y,-1+z
a) Disordered atoms (see exp Section);S3 sulfur of lattice thiocyanate.
Complex 6
D-H
d(D-H)
0.90(3)
0.86(3)
0.85
d(H..A)
1.86(3)
2.04(2)
2.12
<DHA
164(2)
163(2)
172
d(D..A)
2.743(3)
2.873(3)
2.967(3)
3.233(2)
A
Symmetry code of A
-1+x,1/2-y,1/2+z
N2-H2n
N4-H4n
O1w-H1b
O1w-H1a
O1w
N7
N7
S3
-
-
0.85
2.39
175
x,1/2-y,-1/2+z
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Complex 7
D-H
O1w-H11C
O1w-H11D
O2w-H12C
d(D-H)
0.82(2)
0.75(3)
0.85(3)
d(H..A)
<DHA
173(2)
172(4)
166(4)
d(D..A)
A
Symmetry code of A
2.02(2)
2.10(3)
1.98(3)
2.841(3)
2.839(3)
2.815(3)
O2w
N4
N3
1-x,1-y,1-z-
-x,1-y,1-z-
Phosphatase like activity
The phosphatase like activity of the mononuclear manganese(III) complexes was studied in
aqueous DMF (DMF: water = 97.5:2.5) using disodium salt of (4-nitrophenyl)-phosphate
hexahydrate (4-NPP) as model substrate. The hydrolytic behaviour of the complexes was
investigated spectrophotometrically by monitoring the formation of p-nitrophenolate ion (λmax
= 424 nm) with time in aqueous DMF, where the substrate catalyst molarratio in the reaction
mixture was 1:20. The spectral change of complexes 2 and 7 having the highest activity
among complexes 1-3(dependency of halo ligand) and complexes 4-7 (dependency of ligand
backbone), respectively, is shown in Fig.10, as representative of all mononuclear complexes.
Figs. S21-S25 show the spectral change behaviour and kinetics plot forall other complexes.
(a) (b)
Fig. 10 Wavelength scan for the hydrolysis of 4-NPP in the absenceand presence of (a)
complex 2 and (b) complex 7 (substrate:catalyst =20:1) in 97.5% DMFrecorded at 25 °C at
intervals of 5 min for 2 h.
Kinetic Studies of the Hydrolysis of 4-NPP in 97.5% (v/v) DMF-H2O:
The kinetic study of complexes 1-7 was performed by initial slope method following the rate
of increasein absorption of the band at λmax ~ 427 nm, corresponding to the rise of 4-
nitrophenolate concentration in aqueous DMF solution. To determine the dependence of rate
constants on substrate concentration, complexes1-7 were treated with five different
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concentrations of substrate. The kinetic parameters (Vmax, KM, kcat) for the catalyzed reactions
were determined by applying non-linear least square method of Michaelis-Menten treatment
of enzymatic kinetics. All the kinetic parameters are summarized in Table 6. From the kinetic
data the rate order is as follows 2>3>1>7>4>6>5 according to the kcat value. The plots of
enzymatic kinetic for complexes 2 and 7 are reported in Supporting Information (Fig. S26),
while those of other complexes 1, 3, 4, 5 and6 are depicted in Figs. S21-S25
Table 6 First-order kinetic parameters for phosphatase activity obtained by non-linear least
square method of complexes 1-7.
kcat(sec-1)
Vmax
KM
S.D.
Complex
8.128
4.064×10-4
3.79×10-3
1.26×10-4
1
10.168
9.766
7.450
3.610
3.980
7.862
5.048×10-4
4.883×10-4
3.725×10-4
1.805×10-4
1.890×10-4
3.931×10-4
2.38×10-3
3.15×10-3
1.64×10-3
7.34×10-4
1.23×10-3
1.80×10-3
2.62×10-5
1.08×10-4
4.61×10-5
6.70×10-6
1.73×10-5
4.83×10-5
2
3
4
5
6
7
Mechanistic implications
To investigatethe mechanistic pathway of manganese(III) complexes, these were divided into
two sections, the former comprising complexes 1-3 (change in halo anion), and the second 4-
7(change in ligand backbone). During phosphatase activity the substrate molecule binds the
complex as a nitrophenylphosphate ester monoanion and this intermediate species was
trapped by ESI-MS spectroscopy (Table 7). In both groupsof complexesthe rate determining
step in the mechanistic pathway is thatwhere the labile ligand(s) gets dissociated from the
metal centre (Fig.11) after the addition of 4-NPP as reported in our earlier studies.29,30,37 The
actual binding mode of 4-NPP cannot be accessed from ESI-MS study. The earlier studies
help us to assume that binding in a bidentate fashion is most likely. Then the next step is
carried out by the nucleophilic attack of water molecule to the phosphorus atom (Fig. 11). In
complexes1, 2, and 7 the water molecule is already coordinated to the Mn(III) centre, hence
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the rate of the reaction is likely to be higher than for rest of the complexes. However complex
4, which exists as a co-crystal, shows dipositive charge in solution; hence approach of mono-
anion is more feasible than for 5 and 6. Moreover for complexes 4-7 electronegative atoms
present in the hetero-ring also plays a major role. Complex 7 containing oxygen atom in
hetero ring (morpholine) shows the highest catalytic activity followed by complex 4
(piperazine), complex 6 (pyrrolidine) and complex 5 (piperidine). The result is well in
agreement with previous reports.30 Fig.11 shows the mechanistic pathway for complexes 4-7,
where Y denotes the auxiliary part of ligand, whilemechanistic pathway for complexes 1-3 is
shown in Fig. S27.
Table 7Exact mass and molecular formula of intermediate species determined by ESI-MS
study.
Complex
Mass of intermediate species (m/z)
Molecular formula
Fig.
Observed(amu)
779.6785
Calculated(amu)
780.1818
1-3,7
C32H41MnN5O11P+Na+
C34H45MnN5O9P+Na+
C32H40MnN7O8P+Na+
C32H41MnN5O9P+Na+
S28
S29
S30
S31
773.1155
776.2233
4
5
6
756.6451
758.4865
748.5391
748.1920
Fig.11 Proposed mechanism for catalytic cycle of complexes 4-7 in 97.5% DMF-H2O.
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Conclusions
The presence of water or hydroxyl group in the coordination sphere of the catalyst is crucial
in controlling the catalytic efficiency towards the phosphor-ester bond hydrolysis, and the
present study verifies that very concept. Complex 2 having two water molecules coordinated
to the metal centre shows the highest catalytic efficiency, but halo counter ion has different
influence in complexes with water in the inner sphere and in turn in controlling the catalytic
efficacy. Role of auxiliary part of the ligand has further been verified in this study. The
complex with auxiliary part comprising of more electronegative atom shows higher
phosphatase activity, as we noticed earlier [using X=(CH2)2-O-(CH2)2 and (CH2)2-CH2-
(CH2)2] and here the concept is confirmed with a wider range using additionally X = (CH2)2-
NH-(CH2)2 and (CH2)2-(CH2)2. Some of the intermediates of the proposed mechanistic
pathway have been characterized by ESI-MS study, thus it may be stated that catalysts work
most probably by following the proposed mechanism.
Acknowledgements
The authors wish to thank University of Calcutta for providing the facility of ESI-MS
spectrophotometer from the DST-PURSE program. T.C is thankful to UGC,India [Ref. No:
21/06/2015(i) EU-V] for providing fellowship. S.D is thankful to CSIR, India (CSIR Grant
No: 09/028(1023)/2018-EMR-I) for providing fellowship. Financial assistance from DST-
WB (Sanction memo no. 681(sanc)/ST/P/S&T/15G-8/2016 dt 09/11/2016) to DD has been
duly acknowledged.
Supporting information
FT-IR spectra, UV-Vis spectra, CCDC number of crystals, ESI-MS study of complexes, Plot
of enzymatic kinetics, ESI-MS study of intermediates, crystal packing of complexes 1-3, 6,
and 7 are present in Supporting Information.
Author information
Corresponding Author
E-mail: dasdebasis2001@yahoo.com
E-mail: ezangrando@units.it
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References
1
2
F. J. Farrell, W.A.Kjellstrom, Spiro, T. G. Science (Washington,D.C.)1969, 164, 320.
B.Anderson, R. M. Milburn, J.M.Harrowfield, G.B.Robertson,A.M.Sargeson,J. Am.
Chem. Soc. 1977,99, 2652.
3
4
D. R. Jones, L. F. Lindoy, A. M. Sargeson, J. Am. Chem. Soc.1983, 105,7327.
J. M. Harrowfield, D. R. Jones, L. F. Lindoy, A. M. Sargeson, J. Am. Chem.
Soc.1980,102,7733.
5
6
7
8
9
D. R. Jones, L. F. Lindoy, A. M. Sargeson, J. Am. Chem. Soc.1984, 106, 7807.
P. Hendry, A. M. Sargeson, Aust. J. Chem. 1986, 39, 1177.
S. H. Gellman, R. Petter, R. Breslow, J. Am. Chem. Soc.1986, 108,2388-2394
V. Scheller-Krattiger, H. Siegel, Inorg. Chem 1986, 25, 2628.
.
.
H. Sigel, F. Hofstetter, R. B. Martin, R. M. Milburn, J.Scheller-Krattiger, K. H. Scheller,
J. Am. Chem. Soc.1984, 106,7935.
10 G. P. Haight, Jr.Coord. Chem. Rev.1987, 79,293.
11 R. N. Bose, R. D. Cornelius, R. E.Violo, Inorg. Chem.1985, 24, 3989-3996.
12 P. R. Norman, R. D. Cornelius, J. Am. Chem. Soc.1982, 104, 2356.
13 J. D. Sreedhara, J. A. Freed , J. A. Cowan, J. Am.Chem. Soc. 2000, 122,8814.
14 F.Manicin, P.Scrimin, P.Tecilla, U.Tonellato, Chem.Commun. 2005, 2540.
15 D. S. Sigman,Biochemistry 1990, 29, 9097.
16 P. U. Maheswari, S. Roy, H. Dendulk, S. Barends, G. V. Wezel, J. Reedijk, J. Am. Chem.
Soc. 2006, 128, 710.
17 E. Kimura, T. Koike,Adv.Inorg. Chem. 1997, 44, 229.
18 J. E. Coleman,Curr. Opin. Chem. Biol. 1998, 2, 222.
19 B.Bauer-Siebenlist, F. Meyer, E. Farkas, D. Vidovic, S. Dechert,Chem.Eur. J. 2005, 11,
4349.
20 S. K. Hefler, B. A. Averill,Biochem. Biophys. Res. Commun. 1987,146,1173-1177.
21 S.K. Barman,T. Mondal, D. Koley, F. Lloret, R. Mukherjee,Dalton Trans.2017, 46,4038.
22 (a)P. Karsten, A. Neves, A. J. Bortoluzzi, M. Lanznaster,V. Drago, Inorg. Chem.,2002,
41, 18. (b) S. Bosch, P. Comba, L. R. Gahan, G. Schenk, Inorg. Chem. 2014, 53, 9036-
9051. (c) V. K. Bhardwaj, A. Singh, Inorg. Chem. 2014, 53, 10731-10742. (d) J. Chen, X.
Wang, Y. Zhu, J. Lin, X. Yang, Y. Li, Y. Lu, Z. Guo, Inorg. Chem. 2005, 44, 10. (e) N.A.
Rey, A. Neves, A. J. Bortoluzzi, C. T. Pich, H. Terenzi, Inorg. Chem. 2007, 46, 2. (f)J. J.
Boruah,D. Kalita,S. P. Das,S. Paul, N. S. Islam, Inorg. Chem. 2011,50, 8046-8062. (g)M.
20

Page 21 of 22
New Journal of Chemistry
View Article Online
DOI: 10.1039/C8NJ02634C
A. Camargo,A. Neves,B. Szpoganicz, A. J. Bortoluzzi, F. L. Fischer, H. Terenzi, E. E.
Castellano, Inorg. Chem.,2010,49, 3057-3063.(h)M. Lanznaster,A. Neves,A. J.
Bortoluzzi,B. Szpoganicz, E. Schwingel, Inorg. Chem.,2002,41, 5641-5643.
23 H. Sigel, F. Hofstetter,Eur. J. Biochem.1983, 13 ,569.
2
24 M. Jarenmark, S. Kappen, M. Haukka, E. Nordlander, Dalton Trans. 2008, 993-996.
25 M. Jarenmark, E. Csapó, J. Singh, S. Wöckel, E. Farkas,F. Meyer, M. Haukka, E.
Nordlander, Dalton Trans. 2010, 8183.
26 B. Bauer-Siebenlist, F. Meyer, E. Farkas, D.Vidovic, S. Dechert,Chem.Eur. J.2005, 11,
4349.
27 R. Sanyal, A. Guha, T. Ghosh, T. K. Mondal, E. Zangrando, D. Das, Inorg. Chem.2014,
53, 85.
28 R. Sanyal, X. Zhang, P. Kundu, T. Chattopadhyay, C. Zhao, F. A. Mautner , D. Das,
Inorg. Chem. 2015, 54, 2315.
29 R.Sanyal, X. Zhang, P. Chakraborty,C. Zhao, F. A. Mautner , D. Das, RSC
Advances,2016,6, 73534.
30 J. Adhikary, I. Majumdar,P. Kundu, H. Kornweitz, H. Kara, D. Das,
ChemistrySelect2018, 3, 1445.
31 I. Majumdar,P. Chakraborty, J. Adhikary, H. Kara, E. Zangrando, A. Bauzá, A. Frontera,
D. Das, ChemistrySelect,2016, 3, 615.
32 SAINT. SMART, Software Reference Manual;Bruker AXS Inc.: Madison, WI,2000.
33 W. Kabsch, XDS.ActaCryst.D. 2010,66,125.
34 G. M. Sheldrick, ActaCrystallogr. Sect. D2008, 64,112-122.
35 L. J. Farrugia, J. Appl. Crystallogr.1999,32, 837.
36 A.Chakraborty, S. Dasgupta, S. Chatterjee, M.I. Menendez, D. Das, T. Chattopadhyay,
Chemistry select.2017, 2, 8686.
37 P. Chakraborty,J. Adhikary, R. Sanyal, A. Khan , K. Manna, S. Dey , E. Zangrando, A.
Bauzá , A. Frontera, D. Das,Inorg.Chim. Acta.2014, 421, 364.
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Table of Contents
The influences of auxiliary part of ligands and halo ligands have been explored towards
phosphatase like activity using a series of manganese(III)-Schiff base complexes as catalysts.