Inorganic-organic hybrid compounds exhibiting both magnetic order and non-linear optical properties

Article abstract of DOI:10.1016/j.ssc.2009.03.033

Hybrid organic-inorganic framework compounds constitute an important class of materials whose properties, especially paired ones, have not been adequately investigated hitherto. In this communication, we report the non-linear optical properties of hybrid

Full text of DOI:10.1016/j.ssc.2009.03.033

Solid State Communications 149 (2009) 908–910
Contents lists available at ScienceDirect
Solid State Communications
journal homepage: www.elsevier.com/locate/ssc
Inorganic–organic hybrid compounds exhibiting both magnetic order and
non-linear optical properties
a
b
a,∗
H.S.S. Ramakrishna Matte , A.K. Cheetham , C.N.R. Rao
a
New Chemistry Unit and CSIR Centre of Excellence in Chemistry, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB2 3QZ, United Kingdom
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Hybrid organic–inorganic framework compounds constitute an important class of materials whose
properties, especially paired ones, have not been adequately investigated hitherto. In this communication,
we report the non-linear optical properties of hybrid compounds exhibiting interesting magnetic
properties.
Received 17 March 2009
Accepted 28 March 2009 by D.D. Sarma
Available online 5 April 2009
©
2009 Elsevier Ltd. All rights reserved.
PACS:
7
4
7
5.50.Ee
2.70.Nq
2.80.Ga
Keywords:
A. Hybrid compounds
D. NLO properties
D. Antiferromagnetism
∗
1. Introduction
(hmp = R-methyl-2-pyridinemethanol), which are reported to
be antiferromagnetic and ferroelectric [11]. (Lig)2Tb(H20)2ClO4
(lig =L-lactate), which crystallizes in the polar space group C2, also
appears to exhibit interesting ferroic properties [12]. The present
work explores hybrid materials that show long range magnetic or-
der combined with non-linear optical (NLO) properties such as sec-
ond harmonic generation (SHG).
Hybrid inorganic–organic framework compounds constitute
an important class of materials that has been studied exten-
sively over the last few years due to potential applications
in catalysis, gas separation and storage [1–3]. Other proper-
ties which draw attention to these materials include magnetic,
optical and electronic properties [4,5]. Recently a few hybrid
compounds with ferroelectric properties have been reported, ex-
hibiting ferroelectric hysteresis at room temperature [6,7]. For
example, {(HQA)(ZnCl2)(2.5H2O)}n (HQA = 6-methoxyl-(8S,9R)-
cinchonan-9-ol-3-carboxylic acid) is a one-dimensional com-
pound crystallizing in the non-centrosymmetric, polar space group
P1 with a high dielectric constant [8]. Although the magnetic,
optical and electronic properties of hybrid materials are of
considerable interest, there are very few studies on these as-
pects, particularly on paired properties. Of great current inter-
est are hybrid compounds possessing multiferroic properties [9].
Although SHG is reported in a few hybrid compounds, the coex-
istence of NLO properties with magnetic properties is not common.
We have, therefore, investigated the properties of several hybrid
framework compounds containing transition metal ions and crys-
tallizing in non-centrosymmetric space groups. All the compounds
0
3
are 3-D coordination polymers having I O (I, inorganic and O,
organic) connectivity [3]. Specifically, we have examined the prop-
erties of [Co3(2,6-NDC)
3
(bipy)1.5], (NDC = napahathalenedicar-
boxylate, bipy = bipyridine), I and [Ni3(2,6-NDC)
3
(bipy)1.5], II,
which are reported [13] to be non-centrosymmetric with the space
group C2. The magnetic and non-linear optical properties of I and
II have not been reported previously. We have also studied the NLO
properties of [Mn(1,4 BDC)(1,10 Phen)] (BDC = benzenedicarboxy-
late, Phen = phenanthroline), III, which is reported to crystallize in
the non-centrosymmetric polar space group Cc and order antifer-
romagnetically [14]. Finally, we have measured the NLO properties
of {[Ni(C4H4O5)(H2O)]·H2O}, IV, which is reported to be ferromag-
netic [15], with a polar space group, Cc. We have found that three of
the compounds, I–III, exhibit NLO properties in combination with
Known examples of such materials are [Mn3(HCOO)
6
](C2H5OH)
which exhibits a ferroelectric transition at 165 K and a fer-
rimagnetic transition at 8.5 K, [10] and the enantiomorphous
∗
∗
chiral complexes [Cu(R)-hmp (dca)]n and [Cu(S)-hmp (dca)]
n
∗
Corresponding author. Fax: +91 802 208 2760, +91 802 208 2761.
E-mail address: cnrrao@jncasr.ac.in (C.N.R. Rao).
0
038-1098/$ – see front matter © 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ssc.2009.03.033

H.S.S. Ramakrishna Matte et al. / Solid State Communications 149 (2009) 908–910
909
T = 5K
a
0
0
0
0
.24
.18
.12
.06
(
I)
0.8
I
1
000 Oe
FC
ZFC
0
.0
-
6
-4
-2
0
2
4
6
H (T)
-
0.8
b
0
50
100
150
T (K)
200
250
300
0
.02
II
Fig. 1. Temperature variation of the magnetization of I at 1000 Oe showing the ZFC
and FC data.
0.00
0.02
-
0.2
-0.1
0.0
0.1
0.2
interesting magnetic properties. We consider this observation to
be of interest.
H (T)
-
2. Experimental section
[
Co3(2,6-NDC)
3
(bipy)1.5], I, was prepared by taking a mixture
Fig. 2. Magnetic hysteresis for I and II at 5 K.
of Co(NO3
0
1
)
2
· 6H2O (0.100 g, 0.344 mmol), 2,6-NDCH2 (0.025 g,
.115 mmol), bipy (0.054 g, 0.344 mmol), benzene (1.53 ml,
0
.0016
7.18 mmol), and H2O (6 ml, 0.333 mol) in the molar ratio
0
0
0
0
.012
.010
.008
.006
1000 Oe
◦
of 3:1:3:150:2900 and heating at 180 C for 3 days. The black
(II)
crystalline product of [Co3(2,6-NDC)
3
(bipy)1.5] was collected by
0.0014
100 Oe
filtration.
ZFC
FC
To prepare [Ni3(2,6-NDC)
3
(bipy)1.5], II,
a
mixture of
0
0
0
0
.0012
.0010
.0008
.0006
Ni(NO3
)
2
· 6H2O (0.135 g, 0.403 mmol), 2,6-NDCH2 (0.100 g,
0
50 100 150 200 250 300 350 400
T (K)
0
0
.403 mmol), bipy (0.072 g, 0.403 mmol), and H2O (6.0 ml,
.333 mol) in the molar ratio of 1:1:1:600 was heated in a 23-ml
◦
capacity Teflon-lined reaction vessel at 180 C for 2 days and then
cooled to room temperature. The green crystalline product was col-
lected by filtration using, H2O (10 ml), ethyl alcohol (l5 ml), and
acetone (10 ml).
[
Mn(1,4-BDC)(1,10 Phen)], III, was prepared starting with the
mixture of MnCl2 · 4H2O (0.1 g, 0.5 mmol), 1,4-dicyanobenzene
(
(
0.07 g, 0.5 mmol), 1,10-phenanthroline (0.1 g, 0.5 mmol) and H2O
0
50
100 150 200 250 300 350 400
T (K)
16 ml) in the molar ratio of 1 : 1 : 1 : 1777 sealed in a 23 ml capacity
◦
Teflon-lined reaction vessel and heated 170 C for 72 h. The prism-
shaped yellow crystals were collected by filtration.
Fig. 3. Temperature variation of the magnetization of II at 100 Oe showing the ZFC
and FC data. Inset shows magnetization vs. temperature plot at 1000 Oe.
{
[Ni(C4H4O5)(H2O)] · H2O}, IV, was prepared from a mixture of
nickel(II) acetate tetrahydrate (0.30 g, 1.5 mmol), malic acid (0.20 g,
3
. Results and discussion
2
2
(
.1 mmol), 4,4-bipyridine dihydrate (0.10 g, 0.7 mmol), KOH (0.9 g
.24 mmol), distilled water (7 ml) and anhydrous ethyl alcohol
The temperature-dependence of the magnetization of I (Fig. 1)
7 ml). The mixture was stirred for 1 h and then heated under
shows divergence between the field-cooled (FC) and zero-field-
cooled (ZFC) data (at 1000 Oe). This behavior, also found at
a field of 100 Oe, is similar to that of a spin glass or a
frustrated magnetic system. I exhibits magnetic hysteresis at low
temperatures (<150 K). In Fig. 2(a) we show the hysteresis curve
at 5 K. We see that the magnetization approaches saturation
and the values of the remnant magnetization and coercive field
are 0.339 emu/g and 5500 Oe, respectively. From the high-
temperature inverse-susceptibility data recorded at 1000 Oe,
we estimate the Curie–Weiss temperature of I to be −300 K,
suggesting dominant antiferromagnetic exchange interactions.
In Fig. 3, we show the temperature-dependence of the
magnetization of II (at 100 Oe). II also exhibits divergence in
the FC and ZFC data and shows a peak in magnetization at low
◦
autogenous pressure at 160 C for three days in a 23 ml Teflon-
lined stainless steel vessel and finally cooled to room temperature.
Purplish-red crystals were filtered, washed with distilled water
and dried at ambient temperature.
Magnetic measurements were carried out with a vibrating
sample magnetometer in a PPMS instrument (Quantum Design).
We also measured the second order nonlinear optical intensity
relative to KDP (Kurtz powder test) by employing a pulsed
Q-switched Nd:YAG laser at a wavelength of 1064 nm with a
pulse width 8 ns and repetition rate of 10 Hz and beam energy of
.2 mJ/pulse. The backward scattered SHG light was collected using
a spherical concave mirror and passed through a Czerny–Turner
monochromator which transmits only 532 nm radiation.
2

9
10
H.S.S. Ramakrishna Matte et al. / Solid State Communications 149 (2009) 908–910
temperatures. This peak disappears when the data are recorded
at 1000 Oe, as can be seen from the inset of Fig. 3. Compound II
exhibits some magnetic hysteresis at low temperatures (Fig. 2(b)),
with small values of the remnant magnetization and coercive field
Acknowledgements
The authors thank Prof. P. K. Das, Indian Institute of Science, for
NLO measurements. AKC thanks the European Research Council for
an Advanced Investigator Award.
(
0.0027 emu/g and 210 Oe respectively). We also notice from
Fig. 2(b) the absence of a tendency for saturation. The magnetic
behavior of II can be considered to be that of a weak canted
antiferromagnet at low temperatures.
References
We have measured the second harmonic generation activity
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I, is 42% with respect to potassium dihydrogen phosphate (KDP),
while in the case of [Ni3(2,6-NDC) (bipy)1.5], II, it is 1.4% with
1
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[
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TN = 15 K) and we find that the SHG activity of this compound
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[
[
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Chem. Soc. 128 (2006) 15074.
In conclusion, we find significant SHG activity in the three
of the hybrid compounds I–III. All these three NLO compounds,
exhibit dominant antiferromagnetic interactions. They do not
show dielectric anomalies or hysteresis in the temperature range
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5462.
[
[
[
[
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(
2008) 77.
3
0–300 K. The ferromagnetic compound IV does not posses
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significant SHG activity. The observation of NLO activity in hybrid
compounds exhibiting long-range magnetic order is of interest
and suggests that it may be possible to find multiferroic hybrid
compounds as well.
(
2001).
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