Supplementary Information
Synthesis
and
characterization
of
mononuclear
copper(II)
complexes of pyridine 2-carboxamide: Their application as catalyst
in peroxidative oxidation and antimicrobial agents
SUVENDU SAMANTA,a,* SHOUNAK RAY,a SUTAPA JOARDAR,b,* and SUPRIYA
DUTTAc
a
Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur,
Howrah 711 103, India
b
Department of Biotechnology, Neotia Institute of Technology, Management and Science,
Jhinga, Diamond Harbour Road, Amira, South 24 Parganas 743368, India
c
Department of Chemistry, Nistarini College, Deshbandhu Road, Purulia, West Bengal 723101,
India
e-mails: samanta.suvendu88@gmail.com (SS) and sutapajor@yahoo.co.in (SJ)
Table S1. Selected bond lengths [Å] and angles [º] for [Cu(HL)2(H2O)2]Cl2 (1)a.
1
Cu–N1
1.9600(20)
Cu–O1
1.9853(16)
Cu–O2
2.4190(20)
O1–Cu–O2
91.16(8)
O1–Cu–N1
82.35(8)
O2–Cu–N1
88.93(8)
O1–Cu–O2A
88.84(8)
O1–Cu–N1A
97.65(8)
O1A–Cu–O2
88.84(8)
O2–Cu–N1A
91.07(8)
O1A–Cu–N1
97.65(8)
O2A–Cu–N1
91.07(8)
O1A–Cu–O2A
91.16(8)
O1A–Cu–N1A
82.35(8)
O2A–Cu–N1A
88.93(8)
For 1: ‘A’ indicates atoms
at (-x, 1-y, 1-z).
a
Table S2. Selected bond lengths [Å] and angles [º] for [Cu(HL)2(ClO4)2] (2)a.
2
Cu1–N1
1.961(3)
Cu1–N1A
1.961(3)
Cu1–O1
1.940(2)
Cu1–O1A
1.940(2)
Cu1–O5
2.612(2)
Cu1–O5A
2.612(2)
O1–Cu1–O5
91.93(7)
O1–Cu1–N1
83.35(10)
O1–Cu1–O1A
180.00
O1–Cu1–O5A
88.07(7)
O1–Cu1–N1A
96.65(10)
O1A–Cu1–O5
88.07(7)
O5–Cu1–O5A
180.00
O5–Cu1–N1A
99.27(10)
O1A–Cu1–N1
96.65(10)
O5A–Cu1–N1
99.27(10)
N1–Cu1–N1A
180.00
O1A–Cu1–5A
91.93(7)
O1A–Cu1–N1A
83.35(10)
O5A–Cu1–N1A
80.73(10)
a
‘A’ indicates atoms at (1-x, 2-y, -z).
Table S3. Selected bond lengths [Å] and angles [º] for [Cu(HL)2(SCN)2] (3)a.
3
Cu–N1
1.9570(20)
Cu–O1
1.9761(19)
Cu–S1
2.8969(7)
S1–Cu–O1
89.79(6)
S1–Cu–N1
89.79(6)
S1–Cu–O1A
90.21(6)
S1–Cu–N1A
90.21(6)
O1–Cu–N1
82.58(8)
S1A–Cu–O1
90.21(6)
O1–Cu–N1A
97.43(8)
S1A–Cu–N1
90.21(6)
O1A–Cu–N1
97.42(8)
S1A–Cu–O1A
89.79(6)
S1A–Cu–N1A
89.79(6)
O1A–Cu–N1A
82.58(8)
For 3: ‘A’ indicates atoms
at (2-x, 2-y, -z).
a
Table S4. Crystallographic data for [Cu(HL)2(H2O)2]Cl2 (1), [Cu(HL)2(ClO4)2] (2) and
[Cu(HL)2(SCN)2] (3).
1
2
3
Empirical formula
C12H16Cl2N4O4Cu C12H12Cl2N4O10Cu C14H12N6O2S2Cu
M
414.73
506.700
423.96
T, K
296(2)
120(2)
296(2)
Crystal system
Monoclinic
Triclinic
Triclinic
Space group
P21/c
P-1
P-1
a/Å
6.3021(8)
5.7795(16)
6.5714(4)
b/Å
10.0611(12)
9.018(2)
7.3557(5)
c/Å
13.9582(16)
9.213(3)
9.6554(6)
α/°
90.00
90.00
96.749(3)
β/°
113.489(6)
93.796(6)
92.864(3)
γ/°
90.00
101.721(7)
109.313(3)
U/Å3
811.70(17)
442.3(2)
435.43(5)
Z
2
1
1
D/g cm-3
1.697
1.902
1.617
/mm-1
1.698
1.602
1.515
F(000)
422
255
215
Crystal size/mm
0.300.250.22
0.250.200.20
0.200.180.15
No. of measured reflections
9953
5338
6743
No. of observed reflections
1345
1712
2009
Parameters refined
118
133
123
No. of reflections [I >2σ (I)]
1177
1523
1678
Goodness of fit, S[a]
1.067
1.064
1.149
Final R1[b], wR2[c] [I >2σ (I)]
0.0348, 0.0806
0.0400, 0.1057
0.0318, 0.0840
R1[b], wR2[c] (all data)
0.0401, 0.0828
0.0453, 0.1117
0.0409, 0.0983
S = [∑w(Fo2 – Fc2 )/(N – P)]½ where N is the number of data and P the total number of
parameters refined. b R1(F) = ||Fo| – |Fc|||Fo|. c wR2(F2) = [w(Fo2 – Fc2)2/w(Fo2)2]1/2.
a
Table S5. Metrical parameters for H-bonding, C–H···π, π···π interactions in compound 4.
D–H···A
H- bonding
π···π
D–H
distance (Å)
0.970(12)
0.71(6)
0.74(4)
0.86(4)
0.82(5)
0.90(6)
0.802(6)
0.84(2)
0.96(6)
0.864(3)
0.822(2)
0.864(3)
0.822(2)
0.818(3)
0.895(7)
H···A
distance (Å)
2.090(12)
2.22(6)
2.06(4)
1.91(4)
1.95(5)
2.05(6)
2.008(6)
2.31(6)
1.72(5)
1.940(4)
2.153(6)
1.817(4)
2.150(6)
1.951(4)
2.317(10)
D···A
D–H···A
distance (Å)
angle (deg)
O(11)–H(11B)···O(8)
2.862(6)
135(2)
O(5)–H(5B)···O(12)
2.859(5)
150(1)
O(7)–H(7A)···O(6)
2.777(4)
166(1)
O(7)–H(7B)···O(5)
2.719(4)
157(1)
O(10)–H(10A)···O(7)
2.748(4)
158(1)
O(10)–H(10B)···O(8)
2.772(5)
136(1)
O(6)–H(6WA)···O(11)
2.784(5)
163(2)
O(12)–H(12A)···O(11)
2.868(5)
124(1)
O(11)–H(11A)···O(1)
2.678(3)
178(2)
O(5)–H(5A)···O(2)
2.795(3)
171(1)
O(9)–H(9A)···O(2)
2.950(5)
163(1)
O(8)–H(8WA)···O(3)
2.744(3)
160(1)
O(9)–H(9B)···O(3)
2.897(5)
159(1)
O(6)–H(6WB)···O(4)
2.762(3)
171(1)
O(12)–H(12B)···O(4)
2.963(5)
129(1)
π···πa atoms
π···π, distance (Å)
πN(1)···C(5)···πN(5)···C(17)
3.701
πN(3)···C(11)···πN(5)···C(17)
3.693
a
π designates the centroid of the aromatic ring.
symmetry code
x,1+y,z
-x,1-y,1-z
x,1+y,z
1+x,y,z
symmetry code
x,-1+y,z; -x,1-y,1-z
x,-1+y,z; 1-x,-y,-z
Table S6. UV–Vis and deconvoluted absorption peaks for complexes 1–4 in methanol.
max/nm
Deconvulated
(/ M1 cm1)
peaks (nm)
[Cu(HL)2(H2O)2]Cl2 (1)
756 (86)
688, 788, 942
[Cu(HL)2(ClO4)2] (2)
748 (115)
645, 718, 864
[Cu(HL)2(SCN)2] (3)
672 (60)
696, 788, 853
[CuL2]·8H2O (4)
570 (80)
548, 616, 655
Compound
Table S7. Electrochemical dataa for complexes 1–4.
Compound
E1/2b(mV)
ΔEpc
1
435
133
2
57.5
115
3
387.5
135
4
-573 (Ep,a)
-
a
All the potentials are against
Ag/AgCl
reference
electrode,
solvent: dimethyl formamide (dmf),
sacn rate: 100 mV s1.
b
E1/2 values are the average of
those
obtained
from
cyclic
voltammetric and square wave
voltammetric measurements, which
are within ±5 mV.
c
ΔEp refers to the peak to peak
separation at a scan rate of 100 mV
s 1 .
Synthesis of Pyridine 2–carboxamide (HL)
The synthesis of ligand pyridine 2-carboxamide was carried out following the method
reported earlier [26]. It was recrystallized from methanol. Anal. Calcd. for C6H6N2O: C, 59.09;
H, 5.82; N, 22.99. Found: C, 59.01; H, 4.75; N, 22.94. FT–IR (KBr, ν/cm−1): 3342 br, w, 3056 w,
br, 1680 s, 1588 s, 1567 s, 1469 s, 1446 s, 1386 m, 1288 m, 1155 m, 1116 s, 1078 w, 1039 m,
979 s, 885 s, 792 s, 771 s, 719 m, 653 m, 621 w. 1H NMR (500 MHz, (CD3)2SO): δH 8.508 (d,
1H, Ar, J = 5.0), 8.140 (d, 1H, J = 8.0), 7.806–7.773 (m, 2H), 7.38 (dd, 1H, J = 5.5, 2), 5.767 (s,
br, 2H).
[Cu(HL)2(H2O)2]Cl2 (1)
The thermal ellipsoid representation of the cation [Cu(HL)2(H2O)2]2+ is shown in Figure
2 and the selected bond lengths and bond angles are listed in Table 1. The copper is 6-coordinate
with N2O4 donor environment, the basal plane of which is formed by the pyridine nitrogens
N(1)/N(1A) and the amide oxygens O(1)/O(1A), while the oxygen atoms O(2)/O(2A) of the two
water molecules occupy the axial positions. In the equatorial plane, the bond length of Cu–
N(1/1A) [1.9600(20) Å] is almost identical to that of Cu–O(1/1A) [1.9853(16) Å]. The FeO(water) distance [2.4190(20) Å] is significantly longer relative to the Fe-O(amide) distance
[1.9853(16) Å]. The cis angles involving the metal centre range from 82.35(8)º to 97.65(8)º.
Thus, the overall coordination geometry of copper(II) is slightly distorted octahedral.
An interesting feature of the molecular structure of 1 is the occurrence of three
intermolecular hydrogen bonds involving metal-coordinated water molecules, ligand amide
moieties and uncoordinated chloride atoms. The oxygen atoms of the coordinated water
molecules and nitrogen atoms of amide groups act as donors and the chloride anion as the
acceptors. The donor–acceptor D····A distances lie between 3.213(3) and 3.286(2) Å and the D–
H····A angles range from 161(3)º to 170(3)º, indicating that the hydrogen bonds are strong
enough. As shown in Figure S2, these intermolecular hydrogen bonds form a two dimensional
network.
Cu(HL)2(SCN)2] (3)
The molecular structure of the complex [Cu(HL)2(SCN)2] is shown in Figure 3 and the
relevant bond distances and angles are given in Table 1. The coordination environment around
the six-coordinated metal centre [CuN2O2S2] may be considered as slightly distorted octahedral.
The basal plane of octahedron is formed by the pyridine nitrogens N(1)/N(1A) and the amide
oxygens O(1)/O(1A), while the oxygen atoms S(1)/S(1A) of the two thiocyanate anion occupy
the axial positions. In the equatorial plane, the bond length of Cu–N(1/1A) [1.9570(20) Å] is
almost identical to that of Cu–O(1/1A) [1.9761(19) Å]. The cis angles involving the metal centre
range from 82.58(8)º to 97.43(8)º, which indicates the overall coordination geometry of
copper(II) is slightly distorted octahedral.
Two N–H····N hydrogen bonds, involving amide moieties and nitrogen atoms of
thiocyanate anions, link the components into a two-dimensional framework (Figure S3). The
nitrogen atoms of amide groups act as donors and the nitrogen atoms of thiocyanate anion as the
acceptors.
Figure S1. An ORTEP representation of the molecule [Cu(HL)2(ClO4)2] (2) showing 50%
probability displacement ellipsoids. Hydrogen atoms in the crystal lattice are omitted for clarity.
Figure S2. An ORTEP representation of the cation [Cu(HL)2(H2O)2]2+ in 1 showing 50%
probability displacement ellipsoids. Hydrogen atoms and non-coordinated anions in the crystal
lattice are omitted for clarity.
Figure S3. An ORTEP representation of the molecule [Cu(HL)2(SCN)2] (3) showing 50%
probability displacement ellipsoids. Hydrogen atoms in the crystal lattice are omitted for clarity.
Figure S4. A perspective view of the 2-D network developed by intermolecular hydrogen
bonding involving the coordinated perchlorate anions and amide (–NH2) hydrogens in compound
[Cu(HL)2(ClO4)2] (2).
Figure S5. A perspective view of the 2-D network developed by intermolecular hydrogen
bonding involving the coordinated water molecules, chloride anions and amide (–NH2)
hydrogens in compound [Cu(HL)2(H2O)2]Cl2 (1).
Figure S6. A perspective view of the 2-D network developed by intermolecular hydrogen
bonding involving the coordinated thiocyanate anions and amide (–NH2) hydrogens in compound
[Cu(HL)2(SCN)2] (3).
Figure S7. A perspective view of the 3-D network of water channels developed by
intermolecular hydrogen bonding involving the lattice water and amide (–NH2) hydrogens of
[Cu(L)2]·8H2O (4). Red balls represent the array of water channels.
a
c
b
d
Figure S8. Cyclic voltammograms of (a) [Cu(HL)2(H2O)2]Cl2 (1); (b) [Cu(HL)2(ClO4)2] (2); (c)
[Cu(HL)2(SCN)2] (3); [Cu(L)2]·8H2O (4) in acetonitrile and at a scan rate of 100 mV s1.
Figure S9. pH titration curves of 10.0 mM [Cu(HL)2(H2O)2]Cl2 (1) in 25 mL of water.
Scheme S1. Probable mechanistic pathway of catalytic reactions