Quantitative estimation of the antiferromagnetic interaction between Cu(II) and Sm(III) in two dimensional heterometallic coordination polymer with isonicotinic acid as tectons

Article abstract of DOI:10.1016/j.inoche.2013.08.032

The syntheses structure and magnetic property of a novel two dimensional 3d-4f coordination polymer.

Full text of DOI:10.1016/j.inoche.2013.08.032

Inorganic Chemistry Communications 36 (2013) 212–215
Contents lists available at ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Quantitative estimation of the antiferromagnetic interaction between
Cu(II) and Sm(III) in two dimensional heterometallic coordination
polymer with isonicotinic acid as tectons
a,
a
a
b
c
Sandip Saha ⁎, Debabrata Biswas , Partha Pratim Chakrabarty , Dieter Schollmeyer , Atish Dipankar Jana ,
d
e
Hiroshi Sakiyama , Masahiro Mikuriya
Department of Chemistry, Acharya Prafulla Chandra College, New Barrackpur, Kolkata 700131, India
Institut fur Organische Chemie, Universit at Mainz, Duesbergweg 10-14, 55099 Mainz, Germany
Department of Physics, Behala College, Parnasree, Kolkata 700 060, India
Department of Material and Biological Chemistry, Faculty of Science, Yamagata University, 1-4-12, Kojirakawa, Yamagata 990-8560, Japan
Department of Chemistry and Research Center for Coordination Molecule-based Devices, School of Science and Technology, Kwansei Gakuin University, Gakuen 2-1, Sanda 669-1337, Japan
a
b
c
d
e
a r t i c l e i n f o
a b s t r a c t
Article history:
The syntheses, structure and magnetic property of a novel two dimensional 3d–4f coordination polymer
Received 17 July 2013
Accepted 29 August 2013
Available online 5 September 2013
2
2−
∞
[CuSmL(NO
3
)
2
(IN)], 1 (L
= N, N′- propylenedi (3-ehoxysalicylideneiminato), the dianion of the
Schiff base obtained from the 2:1 condensation of 3-ethoxysalicylaldehyde with 1,3-propanediamine,
−
IN = the isonicotinate ion) has been reported. The heterobinuclear units are connected through exo-
−
bidentate ligands IN , leading to an extended 2D structure. A fit of the magnetic susceptibility data yields
Keywords:
Heterometallic
Coordination polymer
Two dimensional
Antiferromagnetic interaction
−
1
−1
g
Cu = 2.109, gSm =0.476, JCuSm = −0.893 cm , θ = −3.37 K, and TIP = 0.001257 emu K mol with
5
a good discrepancy factor of R
tiferromagnetic interaction between Cu(II) and Sm(III) ions to the best of our knowledge.
= 4.4 × 10− . This is the first quantitative estimation of the strength of the an-
χ
© 2013 Elsevier B.V. All rights reserved.
The node-and-spacer approach is a widely used strategy for the
construction of a large variety of 3d–4f coordination polymers
1–3]. It relies upon the strong directionality of the coordination
with one or two carboxylato oxygen atoms [7,9]. From the magnetic
view-point, the understanding of the magnetic properties of complexes
that involve 4f ions is still far from being satisfactory. The magnetic
properties of the most rare-earth ions are strongly influenced by the or-
bital component of the magnetic moment. The ligand-field effects and
the exchange interactions between the magnetic centers become rele-
vant at the same temperature's range. This makes the analysis of the
magnetic behavior of such compounds very difficult [13]. Until now,
the generality of Cu–Gd ferromagnetic coupling has been correlated
with the large occurrence of approximate pseudo-C2v geometry of
these complexes due to the metal ions linked by two phenoxo bridges
[14]. The quantitative description of the magnetic properties of Cu(II)
and Sm(III)-containing heterometallic complexes is not an easy task be-
cause of the ligand-field effect and spin–orbit coupling of the Sm(III) ion
[6,15]. A qualitative approach and a semi-quantitative approach have
been taken to investigate the magnitude of exchange interaction be-
tween Cu(II)–Sm(III) containing 3d–4f coordination polymers [6,15].
In this communication we report on the synthesis [16], crystal struc-
ture and first time quantitatively estimated antiferromagnetic interac-
tion between Cu(II) and Sm(III) ions of a novel 2-D coordination
[
bonds established between the metal ions (nodes and connectors)
and the exodentate ligands (spacers and linkers) [1–3]. Coordination
polymers can be constructed from oligonuclear nodes as well [4–9].
The metal ions interact with the divergent ligand through their easily
accessible coordination sites. The presence of two or more metal
ions confers a higher geometrical flexibility to the node. Moreover, the
metal–metal intra- and inter-node interactions can lead to new redox,
electric, or magnetic properties. The exodentate ligands with oxygen
donor atoms are supposed to interact preferentially with the oxophilic
4
f cations, while the exodentate ligands bearing nitrogen atoms will pre-
fer the Cu(II) ions. Indeed, various network topologies were obtained by
employing spacers with only oxygen, only nitrogen, or both oxygen and
nitrogen donor atoms [1–9].
A quite interesting tecton in constructing extended structures is the
−
isonicotinate anion, IN , an unsymmetrical divergent ligand bearing, at
one end, the nitrogen atom and, at the other one, the oxygen atoms
from the carboxylato group [7,9–12]. It can coordinate to a metal ion
mainly 3d) through the nitrogen atom and to a metal ion (mainly 4f)
(
polymer 2
the green colored copper complex [Cu(L )(CH
∞ 3 2
[CuSmL(NO ) (IN)], 1 which has been obtained by reacting
2
−
3
OH)] with Samarium
2−
nitrate and Sodium isonicotinate [L = N, N′- propylenedi(3-
ehoxysalicylideneiminato), the dianion of the Schiff base obtained
from the 2:1 condensation of 3-ethoxysalicylaldehyde with 1,3-
⁎
Corresponding author. Tel.: +91 33 25373297.
E-mail address: sandipsaha2000@yahoo.com (S. Saha).
1387-7003/$ – see front matter © 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.inoche.2013.08.032

S. Saha et al. / Inorganic Chemistry Communications 36 (2013) 212–215
213
The heterobinuclear 2-D complex belonging to the hexadentate
Schiff base containing 3d–4f family has some common features
[
(
17,18]: the copper(II) ion is hosted within the inner compartment
site) of the organic ligand, leading to the [Cu(L2 )(CH
−
OH)]
4
cavity
the N O
2 2
3
moiety, which is then coordinated through the empty outer O
H
N
N
H
to the Sm(III) ion (two oxygen atoms arise from the phenoxo groups,
the two others from the ethoxy ones). The nitrato ions act as bidentate
ligands toward the Sm(III) ion. When one nitrato ligand is replaced with
one isonicotinato group, the desired 2-D compound results. The same
strategies were employed in earlier two cases to obtain these types of
complexes [7,9]. By slow evaporation of the resulting mixture, the
OH HO
green crystals of the compound with the formula 2
were obtained. The crystals were suitable for X-ray diffraction analysis
19]. The infrared spectrum of 1 shows the characteristic bands of
∞ 3 2
[CuSmL(NO ) (IN)],
[
−
1
both nitrato (1384 cm ) and carboxylato groups (νas = 1470 cm−
1
O
O
−
1
s
and ν = 1308 cm ), indicating the substitution of one nitrato ion
by isonicotinato anion.
The crystal structure of 1 is in line with our expectations. Indeed, a
two dimensional coordination polymer is generated out of the binuclear
[
CuSm] units due to the use of isonicotinate ligand. Isonicotante
H2L
gereatestetranuclear [CuSm] units (Fig. 1) by the syn–syn bridging
2
mode of the carboxylato group connecting two Sm(III) ions from the ad-
jacent dinuclear [CuSm] units. Sm(III) occupies the center of inversion
and is doubly bridged by two isonicotinate ligands. Each isonicotinate
also binds to the Cu center of another symmetry related dinuclear
[Cu–Sm] unit. This binding to Cu is in axial direction of the square pyra-
midal coordination environment of Cu. This two way bridging action of
isonicotinate gives rise to a two dimensional coordination polymer
(Fig. 2). The coordination layer is the (−101) plane. Each Sm(III)
Scheme 1. Schematic presentation of the Schiff base used in the synthesis.
propanediamine] (Scheme 1). Any group have not reported on the var-
iable temperature magnetic study of these particular types of two di-
−
mensional 3d–4f coordination polymers containing IN to the best of
our knowledge.
Fig. 1. The ORTEP diagram (30% ellipsoidal probability) of the tetranuclear unit of 1 with atom numbering scheme (* = 1−x,1−y,1−z).

214
S. Saha et al. / Inorganic Chemistry Communications 36 (2013) 212–215
1
7
6
1
6
5
6
6
whereg2 ¼ − g
þ
gSm andg
3
¼
gCu
þ
gSm. The H state of Sm(III)
6
Cu
6
6
6
6
6
6
splits into six states – H5/2, H7/2, H9/2, H11/2, H13/2, and H15/2from
the lower energy – due to the spin–orbit coupling, and the second low-
est H7/2 state is ~700 cm (7λ/2) higher than the lowest H5/2 state
20]. Therefore, the interaction was considered between Cu(II) ion
Cu = 1/2) and the lowest 6
5/2 state of Sm(III) ion (J = 5/2), and
6
−1
6
[
(S
H
6
the effect of the second lowest
shown in the following equations:
H7/2 state was included in TIP as
TIP ¼ TIPCu þ TIPSm
ꢂ
ꢃꢂ
ꢃ
2
2
Nβ g −1 g −2
J
J
TIPSm
¼
:
3
λ
The best-fitting parameters are gCu = 2.109, gSm = 0.476, JCuSm
=
Fig. 2. The two dimensional coordination polymer of 1 by the two way bridging action of
the isonicotinate ligand. For the clarity of the picture, besides the isonicotinate ligand only
coordinated atoms to the metal centers are shown. Sm is magenta and Cu is yellow.
−
1
−1
−0.893 cm , θ = −3.37 K, and TIP = 0.001257 emu K mol with
−
5
a good discrepancy factor of R
χ
= 4.4× 10 . If TIPCu is assumed to be
−
1
−1
0
.000060 emu K mol , TIPSm will be 0.001197 emu K mol and λ
−
1
will be calculated as 207.6 cm , which is normal for Sm(III) complex
20]. The gSm value of 0.476 is noteworthy; it corresponds to (5 g )/
= 10/21 (~0.476) in the cubic ligand field [21] where the g
[
3
J
J
exhibits a coordination number of 10 (Figure S1), the coordination
sphere being formed by oxygen atoms. Four of them arise from the
two chelating nitrato ligands, four others from the compartmental li-
gand (two phenoxo and two ethoxy oxygen atoms), and two oxygen
atoms from the bridging carboxylato groups donated by two isoni-
cotinate ligand. The square pyramidal coordination environment of Cu
is satisfied by two O atoms and three N atoms. The chelating Schiff base
ligand forms the basal plane of the square pyramid of Cu with two O
and two N atoms. This axial coordination is by the isonicotinate N atom.
The Sm–Sm distance in a tetranuclear unit is 5.588 Å. Sm1–O35 and
Sm1–O36 distances are 2.3859(19) Å and 2.342(2) Å, respectively.
Other relevant bond distances and angles are given in Table S1 and
Table S2. The coordination layers which are the (−101) planes succes-
sively stack (Figure S2).
value for Sm(III) ion is 2/7 (~0.286). It is generally difficult to deter-
mine JCuSm and θ correctly when both are in the same sign; however,
the discrepancy factor became a minimum with the best-fitting
parameters.
Consequently, the slow decrease in χ
M
T from 300 K to 20 K is due to
the TIPSm caused by the excited H7/2 state, and the rapid drop below
0 K is due to the intramolecular antiferromagnetic interaction be-
6
2
tween Cu(II) and Sm(III) ions and the intermolecular antiferromagnetic
interactions including Sm(III) · · · Sm(III) interaction. Similar behavior
was reported earlier [15], however, the antiferromagnetic interaction
was not estimated at that time. The interdimer interaction was consid-
ered using theta. So, the interaction through the bis-isonicotinato bridge
is included in theta. Actually, the observed interdimer antiferromagnet-
ic interaction (minus theta) is larger than usual, so the interaction
through the bis-isonicotinato bridge is also expected as antiferromag-
netic. In our analysis, exchange interaction (JCuSm) can be estimated be-
tween Cu(II) and Sm(III) ions, using an equation for 1/2–5/2 system.
Any other groups have not used this approach before for magnetic
data fitting of these types of systems. Therefore, it also precludes its
comparison with those of the other known Cu(II)–Sm(III) systems
The magnetic data of 1 was recorded from 4.5 to 300 K under 0.1 T
−
1
field. The χ
at 300 K to 0.427 emu K mol
M
T value for 1 decreases slowly from 0.868 emu K mol
−
1
at 20 K and then more rapidly to
at 4.5 K. A fit of the data (Fig. 3) was calculated
using the following equation:
−
1
0
.197 emu K mol
ꢀ
ꢁ
2
2
2 JCuSm
[6,15].
2
10 g2 þ 28 g2 exp
Nβ
kðT−θÞ
kT
In conclusion, we have synthesized a novel two dimensional 3d–4f
χ ¼
ꢀ2 J
ꢁ
þ TIP;
CuSm
coordination polymer. With the choice of Cu as one of the metals it gen-
erally gives rise to square planar Cu coordination environment with
hexadentate Schiff bases and suitable choice for the second metal can
give rise to various functional materials especially magnetic one. In
the present study with an intention of designing higher dimensional
magnetic systems we deliberately used Sm as the second metal and
5
þ 7 exp
kT
−
isonicotinate ligand (IN ) as the co-ligand which is suitable for bridging
metal nodes. Additionally, it can also be concluded that further exten-
sion of the approach used for magnetic data fitting will afford to esti-
mate the magnetic interaction in various heterometallic coordination
polymers.
Acknowledgments
Financial support from DST [Sanction no. SR/FT/CS-060/2009] and
UGC [Sanction no. F.38-5/2009 (SR)], New Delhi to S. S. are gratefully
acknowledged.
Appendix A. Supplementary material
M
Fig. 3. Temperature dependence of the χ T versus T for 1 plot is shown with data repre-
sented by open circles and the solid-line fit obtained using the parameters described in
the text.
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.inoche.2013.08.032.

S. Saha et al. / Inorganic Chemistry Communications 36 (2013) 212–215
found: C: 56.00; H: 6.55; N: 6.40%. IR (KBr pellets, cm−1): ν(CH
215
References
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(0.113 g, 0.25 mmol) with constant stirring for 2 hrs. Then 10 ml water solution
of sodium isonicotinate (0.037 g, 0.25 mmol) was added in the previous mixture.
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isolated. On slow evaporation of the resulting green colored solution the green
block shaped single crystals of the complex 1 was separated out in a few days.
The crystals were filtered and washed with methanol and dried in air.Complex 1:
[
[
[
[
[
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H28CuN SmO12: C: 39.11; H: 3.37; N:
5
−
1
8.44%. found: C: 39.12; H: 3.39; N: 8.41%.IR (KBr pellets, cm ): ν(C = N) 1628,
−
−
3 s
ν(NO ) 1384, νas(COO ) 1470, ν (COO ) 1308.
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1
[19] Crystal Data for 1: F W, 828.43; monoclinic, Space group P2 /n; Unit cell dimensions
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a = 12.0007(5) Å, b = 15.5179(5) Å, c = 16.1233(6) Å, β = 100.2352(12); cell vol-
ume, 2954.79 Å ; Z = 4; D = 1.862 g/cm ; μ = 2.761 mm ; T = 293 K, Reflec-
c
tions collected: 7021; Independent reflections: 5946; Final R indices: R = 0.0237,
wR2 = 0.0641. The crystallographic data for 1 was collected on a STOE IPDS 2 T device
3
3
−1
[
[
[
with a STOE detector equipped with graphite monochromated MoK
α
radiation
(
0.074 ml, 1.0 mmol) with 3-ethoxy salicylaldehyde (0.332 g, 2.0 mmol) in metha-
(λ = 0.71073 Å). CCDC-937393 contains the supplementary crystallographic data for
this compound. These data can be obtained free of charge for the Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam. ac.uk/data_request/cif. CIF file for 1. This mate-
rial is available free of charge via the Internet at http://pubs.acs.org. The atomic
coordinates for these structures have also been deposited with the Cambridge Crys-
tallographic Data Centre. They can be obtained, upon request, from the Director,
Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, U.K.
[20] O. Kahn, Molecular Magnetism, VCH, New York, 1993. 46.
nol (10 mL) for two hrs. The ligand was not isolated; instead the resulting yellow
methanolic solutions were subsequently used for complex formation. A clear solu-
tion of Cu(CH3COOH)2. H2O (0.199 g, 1.0 mmol) in methanol (10 mL) was added
to a 10 mL methanolic solution of the L, and the mixed solution was stirred for
0
.5 h. The green colored complex [Cu(L2−)(CH3OH)] was isolated and this com-
plex was further used for the complex preparations L2− = N, N′-propylenedi(3-
2−
ehoxysalicylideneiminato, the dianion of the Schiff base).Complex [Cu(L
)
(
CH OH)]: Yield 65%. Anal.: Cacld.for C22 28CuN : C: 56.95; H: 6.04; N: 6.04%.
3
H
2
O
5
[21] W.M. Walsh Jr., E. Bucher, L.W. Rupp Jr., L.D. Longinotti, AIP Conf. Proc. 24 (1975) 34.