Separation of isomers of sulfophthalic acid by guest induced host framework formation with 4,4′-bipyridine

Article abstract of DOI:10.1039/c1cc11481f

The selective inclusion of aromatic guest molecules in host frameworks formed by 3-sulfophthalic acid or 4-sulfophthalic acid and 4,4′-bipyridine has been effectively utilized for the separation of sulfophthalic acid isomers.

Full text of DOI:10.1039/c1cc11481f

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COMMUNICATION
Separation of isomers of sulfophthalic acid by guest induced host
0
framework formation with 4,4 -bipyridinew
Goutam Mahata, Sandipan Roy and Kumar Biradha*
Received 15th March 2011, Accepted 4th May 2011
DOI: 10.1039/c1cc11481f
4
The selective inclusion of aromatic guest molecules in host
frameworks formed by 3-sulfophthalic acid or 4-sulfophthalic
sulfonated phthalocyanine dyes and for their applications.
Although some chromatographic methods are published for
the separation of these isomers, no simple and convenient
0
acid and 4,4 -bipyridine has been effectively utilized for the
5
separation method for these isomers has been reported. These
separation of sulfophthalic acid isomers.
isomers are of interest to us due to the potential of –COOH
The utility and uniqueness of supramolecular chemistry for the
separation of regioisomeric, geometric, diastereomeric and
enantiomeric mixtures have been well demonstrated in the
3
and –SO H groups to form supramolecular synthons with
pyridine derivatives. Both these isomers are indeed capable of
0
forming host networks when reacted with a 4,4 -bipyridine
1
6
7
literature. The supramolecular methods have been preferred
(BIPY) via synthons I and II. In the present report the
selective host formation was achieved by automatic choice of
guest molecules therefore paving the way for the separation of
these sulfophthalic isomers.
over traditional methods such as chromatography, selective
derivatisation and fractional distillation due to the cost
effectiveness and also due to the ease of separation. Generally,
traditional methods of separation are not feasible for the
separation of molecular isomers as they have almost
identical properties. The most successful and unconventional
methodology is that the host framework selectively chooses
one of the components in the mixture as a guest depending on
the size or shape selectiveness or the favorable interactions
with the host framework. For example, the separation of
several positional isomers has been reported by Nassimbeni
2
and Toda et al. by using diols as hosts. Ward et al. have also
3
demonstrated it but by using two component organic hosts.
Here we present a new methodology in which the separation
of isomers was achieved through selective formation of host
networks based on the presence of an aromatic guest molecule.
The sulfonation reaction of phthalic acid results in mixtures of
4
-sulfophthalic acid (4-H SPA) and 3-sulfophthalic acid
3
(
3-H SPA) due to the nonspecific nature of the reaction.
3
Aldrich sells a chemical with the label of 4-H SPA dissolved
3
in water (50% wt. average 4-sulfophthalic acid) and mentions
3
The 4-H SPA as purchased from Aldrich was crystallized with
1
3
-H
as purchased reveals that the 4-H
: 1 ratio. It was also found that the solution contains 2.5%
of H SO which was confirmed by BaSO estimation. The
3
SPA as a major impurity. The H NMR of this chemical
BIPY in the presence of aromatic guest molecules such as
naphthalene (NAP) and anthracene (ANT) at room temperature
in methanol. The single crystal analyses of the resulting crystals
3 3
SPA and 3-H SPA are in
4
reveal the formation of complexes [(4-HSPA)(H
(1) and [(3-H SPA) (H BIPY) (SO
]ꢀNAP, (2).
In the crystal structure of 1 the asymmetric unit contains
BIPY)]ꢀANT,
2
4
4
2
purity of these isomers is of importance for the syntheses of
2
2
2
3
4 2
)
0
8
one unit each of 4-HSPA, 4,4 -H
deprotonation of –SO H and –COOH which is para to –SO
was confirmed by comparing the S–O (1.488(6), 1.421(8) and
2
BIPY and anthracene. The
Department of Chemistry, Indian Institute of Technology,
Kharagpur-721302, India. E-mail: kbiradha@chem.iitkgp.ernet.in;
Fax: 91-3222-282252; Tel: 91-3222-283346
w Electronic supplementary information (ESI) available: Experimental
analysis and characterization of the compounds by HPLC analysis,
NMR spectra, IR spectra, DRS spectra, powder XRD patterns and
crystallographic information of the compounds explained in detail.
CCDC 817472–817473. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c1cc11481f
3
3
H
˚
˚
1.452(7) A) and C–O (1.245(10), 1.256(10) A) bond lengths.
Each 4-HSPA connected to two adjacent 4-HSPA units via
ꢁ
˚
–
COO ꢀ ꢀ ꢀHOOC charge assisted H-bonds (Oꢀ ꢀ ꢀO 2.560(8) A)
to form a zig-zag chain along the c-axis. These chains are
linked into 3-dimensional network by BIPY via
a
6
614 Chem. Commun., 2011, 47, 6614–6616
This journal is c The Royal Society of Chemistry 2011

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Fig. 1 Illustrations for the crystal structure of 1: (a) 3D hydrogen-bonded network (along c-axis); (b) hydrogen bonding pattern along c-axis;
(c) triply interpenetrated 3D-networks with guest inclusion (space fill mode); interactions involved between the interpenetrated networks; (d) view
2
in ab-plane; (e) view in bc-plane; (f) cation–p interaction between H BIPY and ANT represented in space fill mode (ANT shown in pink color).
+
˚
N –Hꢀ ꢀ ꢀO–C hydrogen bond (Nꢀ ꢀ ꢀO: 2.570(9) A) and synthon-
2
The cation–p charge transfer interaction between H BIPY
˚
˚
II (Nꢀ ꢀ ꢀO: 2.755(10) A and Cꢀ ꢀ ꢀO: 3.306(11) A) (Fig. 1(d) and (e)).
Three such 3D-networks interpenetrate such that there exist
continuous channels which are occupied by anthracene units.
The interpenetration of networks occurs through the plethora
of C–Hꢀ ꢀ ꢀO hydrogen bonds. Further anthracene units are
included such that they are sandwiched by bipyridinium ions
via charge-transfer cation–p interactions with a distance as
and ANT or NAP is confirmed from DRS studies (See ESI).
The DRS results indicate that the complexes 1 and 2 exhibit a
red shift of 168 nm and 81 nm, respectively, when compared
with the l values of guest molecules.
Furthermore the presence of guest molecules such as
phenanthrene or pyrene also resulted in crystals similar to 1
in which exclusively 4-H SPA functions as a host component.
3
+
˚
short as 3.392 A between N and a centroid of one of the
These crystals also exhibit similar coloration to those of 1. The
colors of the crystals are also helpful as colorimetric indicators
in the separation of these isomers. The crystals of 2 contain
lower guest accessible volume compared to those of 1. These
6
outer C rings of the ANT unit (Fig. 1f). As a result the
crystals exhibit an intense pink color (lmax: 560 nm).
The asymmetric unit in the crystal structure of 2 contains
2
4
ꢁ
one unit each of 3-H
2
SPA and SO
, one and a half units of
results demonstrate that 4-H
3
SPA-BIPY forms a host
9
BIPY and a half unit of naphthalene. The C–O (1.311(5)
H
2
framework for the inclusion of bigger guest molecules while
2ꢁ
˚
and 1.205(5) A; 1.332(5) and 1.196(5) A) and S–O bond
˚
3-H
3
SPA-BIPY-SO
4
forms a host framework for the
˚
distances (1.468(4), 1.438(4) and 1.447(4) A) indicate that the
inclusion of relatively smaller guest molecules. The bulk purity
1
13
–
–
COOH groups of 3-H SPA are not deprotonated and only
3
of these crystals has been verified by H NMR, C NMR,
elemental analysis and XRPD patterns. The isomers from the
crystals of 1 or 2 were recovered in the following way. The
aromatic guests were precipitated by treating the crystals with
aqueous NaOH, and BIPY was removed from the resultant
2
ꢁ
SO H is deprotonated. The presence of SO
3
ion in the
4
lattice further confirms the contamination of H SO in the
2
4
2
ꢁ
Aldrich sample. The SO4
-H SPA units to form two-dimensional layers via several
O–Hꢀ ꢀ ꢀO hydrogen bonds (Oꢀ ꢀ ꢀO: 2.534(6), 2.878(5) and
ions join the H BIPY and
2
3
2
3
filtrate by extracting with CHCl . The aqueous portion was
˚
˚
2
.542(5) A) and synthon-II (Oꢀ ꢀ ꢀN, Cꢀ ꢀ ꢀO: 2.665(6), 2.999(7) A)
treated with conc. HCl until the pH was 2 and water was
removed from it by heating the solution. The isomers were
recovered by extracting the resultant solid with MeOH. The
ꢁ
such that the –SO
the layer (Fig. 2a and b). Two such layers are interconnected
3
groups of 3-H SPA point at one side of
2
1
by H
(
2
BIPY units that sit on the inversion centre via synthon-II
˚
H NMR spectrum of 4-H
SPA and pure 3-H
3
3
SPA as purchased from Aldrich,
Oꢀ ꢀ ꢀN, Cꢀ ꢀ ꢀO: 2.740(7), 3.036(8) A) (Fig. 2c). As a result the
pure 4-H
in Fig. 3 (for details please see ESI).
3
SPA after separation are shown
˚
layer has dimension of 16.2 A and also contains channels
to include naphthalene units. The naphthalene units are
sandwiched by bipyridinium ions with somewhat longer
In a typical reaction, 882 mg of crystals of 1 were produced
from 1.292 g of Aldrich solution mixture that contains 503 mg
of 4-H SPA and 126 mg of 3-H SPA. Out of 503 mg of
+
˚
distance of 4.314 A between N and a centroid of one of
3
3
the C
6
rings of the NAP unit indicating a weaker cation–p
4-H
which nearly accounts for 75% of the total amount of
3
SPA, 374 mg have been included in the crystals of 1
interaction compared to that of complex 1 (Fig. 2d). The
crystals exhibit a greenish yellow color (lmax: 400 nm).
4-H
3
SPA in the reaction mixture. Using the above described
This journal is c The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 6614–6616 6615

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Fig. 2 Illustrations for the crystal structure of 2: (a) 2D hydrogen-bonded network and inclusion of naphthalene (space fill mode), hydrogen
bonding interactions involved in the network formation; (b) ab-plane and (c) bc-plane; (d) space fill representation of cation–p interaction between
H
2
BIPY and NAP (green).
2
(a) S. Apel, M. Lennartz, L. R. Nassimbeni and E. Weber,
Chem.–Eur. J., 2002, 8, 3678; (b) M. R. Caira, A. Horne,
L. R. Nassimbeni and F. Toda, J. Mater. Chem., 1997, 7, 2145;
(
c) S. A. Bourne, K. C. Corin, L. R. Nassimbeni and F. Toda, Cryst.
Growth Des., 2005, 5, 379; (d) A. Coetzee, L. R. Nassimbeni and
H. Su, J. Chem. Res. (S), 1999, 436; (e) L. R. Nassimbeni,
G. Ramon and E. Weber, J. Therm. Anal. Calorim., 2007, 90, 31;
(
f) M. R. Caira, L. R. Nassimbeni, F. Toda and D. Vujovic, J. Am.
Chem. Soc., 2000, 122, 9376; (g) M. R. Caira, T. I. Roex and
L. R. Nassimbeni, Chem. Commun., 2001, 2128; (h) F. Toda and
K. Tanaka, Chem. Commun., 1997, 1087; (i) F. Toda, Top. Curr.
Chem., 1987, 140, 43; (j) F. Toda, Supramol. Sci., 1996, 3, 13;
(
(
k) F. Toda and K. Tanaka, Tetrahedron Lett., 1988, 5, 551;
l) F. Toda, CrystEngComm, 2002, 4, 215.
3
4
(a) J. Kim, J. Yia, M. D. Ward and W.-S. Kim, Sep. Purif. Technol.,
009, 66, 57–64; (b) A. M. Pivovar, K. T. Holman and M. D. Ward,
Chem. Mater., 2001, 13, 3018.
2
(a) K. Sakamoto and E. Ohno-Okumura, Color. Technol., 2001,
1
17, 82; (b) M. Ganschow, D. Wohrle and G. Schultz-Ekloff,
J. Porphyrins Phthalocyanines, 1999, 3, 299; (c) S. Takeoka,
T. Hara, K. Fukushima, K. Yamamoto and E. Tsuchida, Bull.
Chem. Soc. Jpn., 1998, 71, 1471.
A. Weisz, E. P. Mazzola, C. M. Murphy and Y. Ito, J. Chromatogr.,
A, 2002, 966, 111.
(a) G. R. Desiraju, Crystal engineering; The Design of Organic
Solids, Elsevier, New York, 1989; (b) G. R. Desiraju, Angew. Chem.,
Int. Ed. Engl., 1995, 34, 2311; (c) C. V. K. Sharma and
1
Fig. 3 H NMR (in D
6
DMSO, 200 MHz) spectra of (a) 4-H
3
SPA as
purchased from Aldrich, (b) pure 4-H
-H SPA after separation.
3
SPA after separation, (c) pure
5
6
3
3
workup procedure 97% of the isomer from the crystals of 1
was recovered. On the other hand, only 32% of 126 mg of
3
-H SPA has been included in the crystals of 2.
In summary, we have shown that the hydrogen bonded host
3
M.
(
J.
Zwarotko,
Chem.
Commun.,
d) P. Vishweshwar, A. Nangia and V. M. Lynch, J. Org. Chem.,
1996,
2655;
2
2
002, 67, 556; (e) K. K. Arora and V. R. Pedireddi, J. Org. Chem.,
003, 68, 9177; (f) S. H. Dale, M. R. J. Elsegood, M. Hemmings and
frameworks of complexes 1 and 2 are selectively chosen by
the guest molecules. Using this selectivity, the isomers of
sulfophthalic acid were separated with ease. The presence of
sulfate ion plays a significant role in the formation of complex 2.
We acknowledge the DST, New Delhi, India, for financial
assistance, DST-FIST for a single crystal X-ray diffractometer
and G. Mahata wishes to acknowledge the UGC, New Delhi,
India for financial support.
A. L. Wilkinson, CrystEngComm, 2004, 6, 207; (g) S. Roy,
G. Mahata and K. Biradha, Cryst. Growth Des., 2009, 9, 5006;
(
(
h) R. Santra and K. Biradha, Cryst. Growth Des., 2009, 9, 4969;
i) D. Weyna, R. T. Shattock, P. Vishweshwar and
M. J. Zaworotko, Cryst. Growth Des., 2009, 9, 1106.
7 (a) L. J. Barbour and J. L. Atwood, Chem. Commun., 2001, 2020;
(
(
b) K. Biradha and G. Mahata, Cryst. Growth Des., 2005, 5, 51;
c) C. B. Smith, M. Makha, C. L. Ratson and A. N. Sobolev, New J.
Chem., 2007, 31, 535.
8
Crystal data for 1: C32
a = 17.683(8) A, b = 11.118(5) A, c = 13.547(6) A, b =
H
24
N
2
O
7
S, M = 580.59, monoclinic, Cc,
˚
Notes and references
˚
˚
3
˚
9
5.469(13)1, V = 2651(2) A , T = 293(2) K, Z = 4; 2364 reflections
1
(a) F. Toda and R. Bishop, Separations and Reactions in Organic
Supramolecular Chemistry: Perspectives in Supramolecular Chemistry,
Wiley, Chichester, 2004; (b) J. W. Steed and J. L. Atwood, Supra-
molecular Chemistry, John Wiley & Sons, UK, 2009; (c) M. Pawloska,
D. Sybilska and J. Lipkowski, J. Chromatogr., A, 1979, 1, 1;
out of 3764 (Rint = 0.0750) with I 4 2s(I), R
and wR = 0.2082 (all data), Flack parameter = 0.5(2).
9 Crystal data for 2: C56 , M = 1285.24, triclinic, P1,
1
= 0.0789 (I 4 2s(I))
2
ꢀ
48 6 22 4
H N O S
˚
˚
˚
a = 8.345(4) A, b = 10.533(5) A, c = 16.280(8) A, a = 10.425(13)1;
3
˚
(d) P. Starzewski, W. Zielenkiewicz and J. Lipkowski, J. Inclusion
b = 93.061(15)1; g = 93.425(13)1; V = 1391.7(12) A , T = 293(2)
K, Z = 1; 2915 reflections out of 4613 (Rint = 0.0472) with
I 4 2s(I), R = 0.0778 (I 4 2s(I)) and wR = 0.2308 (all data).
1 2
Phenom., 1984, 1, 223; (e) P. Starzewski and J. Lipkowski, Pol. J.
Chem., 1979, 53, 1869.
6
616 Chem. Commun., 2011, 47, 6614–6616
This journal is c The Royal Society of Chemistry 2011