Comparison of pyridyl and pyridyl N-oxide groups as acceptor in hydrogen bonding with carboxylic acid

Article abstract of DOI:10.1039/c3ce42449a

Competition experiments between pyridyl and pyridyl N-oxide groups have been performed to find out which of these two groups is a better acceptor in hydrogen bonding with the carboxylic acid group. 4,4′-bipyridine N-monoxide, a rigid, conjugated, and linear molecule and 4,4′- trimethylenebipyridine N-monoxide, a flexible, non-conjugated between two aryl groups, and bent molecule, have been used to synthesize complexes with some carboxylic acid containing compounds. The study shows that although the occurrence of pyridyl...acid synthon is more than the corresponding pyridyl N-oxide...acid synthon, based on the distance criterion and energy calculation, the pyridyl N-oxide...acid synthon is slightly stronger than the pyridyl...acid synthon. Solubility studies also show that the pyridyl N-oxide compound may be a better choice as a coformer than the corresponding pyridyl derivative to increase the solubility of carboxylic acid containing compounds.

Full text of DOI:10.1039/c3ce42449a

CrystEngComm
View Article Online
View Journal | View Issue
PAPER
Comparison of pyridyl and pyridyl N-oxide groups
as acceptor in hydrogen bonding with
carboxylic acid†
Cite this: CrystEngComm, 2014, 16,
4715
Viswanadha G. Saraswatula, Mukhtar A. Bhat, Pradeep Kumar Gurunathan
*
and Binoy K. Saha
Competition experiments between pyridyl and pyridyl N-oxide groups have been performed to find out
which of these two groups is a better acceptor in hydrogen bonding with the carboxylic acid group.
4,4′-bipyridine N-monoxide, a rigid, conjugated, and linear molecule and 4,4′-trimethylenebipyridine
N-monoxide, a flexible, non-conjugated between two aryl groups, and bent molecule, have been used
to synthesize complexes with some carboxylic acid containing compounds. The study shows that
although the occurrence of pyridyl⋯acid synthon is more than the corresponding pyridyl N-oxide⋯acid
synthon, based on the distance criterion and energy calculation, the pyridyl N-oxide⋯acid synthon is
slightly stronger than the pyridyl⋯acid synthon. Solubility studies also show that the pyridyl N-oxide
compound may be a better choice as a coformer than the corresponding pyridyl derivative to increase
the solubility of carboxylic acid containing compounds.
Received 2nd December 2013,
Accepted 13th January 2014
DOI: 10.1039/c3ce42449a
www.rsc.org/crystengcomm
mixed halide–halometallate anions.7 Nangia et al. observed the
synthon competition and cooperation in the molecular salts of
Introduction
Synthons play a very important role in the fields of crystal
engineering and pharmaceutical cocrystals.1 Strong and
robust synthons2 are comparatively more reliable than the
weak interactions3 in the designing strategy of a cocrystal or
a desired network. In a given set of functional groups,
according to Etter's rule,4 the strong donating group would
prefer strong acceptor and weak donor would prefer weak
acceptor. There are several studies on competition experiment
for the preferred synthon available in a reacting medium.
Aakeröy et al. performed some competition experiments to
compare the donating ability of hydroxyl and halogen groups
(F, Cl and I) in the 1 : 1 cocrystals of 1-methyl-2-(4-pyridyl)
benzimidazole with halo substituted oximes.5 They also
have performed similar type of experiments using
3,3′-azobipyridine and 4,4′-azobipyridine, co-crystallized with
bi-functional donor molecules containing halogen-bond
donor (I or Br) as well as a hydrogen-bond donor (acid, phenol
or oxime) on the same backbone to compare hydrogen bond
and halogen bonds.6 Brammer et al. performed competition
experiments between nucleophiles for the hydrogen bond and
halogen bond formation in a series of halopyridinium salts of
hydroxybenzoic acids and aminopyridines.8 Reddy and
co-workers have performed competition experiments between
sulfoxy and pyrimidine groups in the course of studying
pharmaceutical cocrystals of sulfamethazine.9 Recently,
Jagadeesh and coworkers in their competition experiments,
using cytosine–carboxylic acid complexes, found that choice of
a synthon in crystal structure determination depends on the
strength of the acid coformer and the stoichiometry used for
it.10 In pharmaceutical cocrystal the solubility is an important
factor which could be tuned by changing the coformer.11
Generally, strong hydrogen bond donor or acceptor groups are
chosen as coformer to ensure complex formation. Carboxyl,
hydroxyl, etc. groups are known as strong hydrogen bond
donors and pyridyl, pyridyl N-oxide, sulfoxide, are known as
strong hydrogen bond acceptors. Pyridyl N-oxide group is not
as widely used functional group as the pyridyl group in the
formation of complexes with strong hydrogen bond donors.12
Herein, we have performed a competition experiment between
the pyridyl and pyridyl N-oxide groups as an acceptor in
hydrogen bonding with the carboxyl group.
Experimental
Department of Chemistry, Pondicherry University, Puducherry, 605 014, India.
E-mail: binoypu@yahoo.co.in
4,4′-bipyridine (BPY), 4,4′-trimethylenebipyridine, p-coumaric
acid (PCA), α-cyanoparacoumaric acid (CPCA), p-cyanobenzoic
acid (PCBA), and p-nitrobenzoic acid (PNBA) were purchased
from Sigma Aldrich and used as such without further purification.
† Electronic supplementary information (ESI) available: ORTEP diagram,
absorbance vs. wavelength plot, absorbance vs. concentration plot. CCDC
974283–974290. For crystallographic data in CIF or other electronic format see
DOI: 10.1039/c3ce42449a
This journal is © The Royal Society of Chemistry 2014
CrystEngComm, 2014, 16, 4715–4721 | 4715

View Article Online
Paper
CrystEngComm
p-hydroxybenzoic acid (PHBA) was purchased from Loba Chemie
and m-chloroperoxybenzoic acid was purchased from Himedia.
CDCl3 and mesitylene were purchased from Sigma Aldrich. All
other solvents were purchased from S D Fine-chem. 1H NMR
spectra were recorded on Bruker 400 MHz instrument.
4,4′-bipyridine N-monoxide (BPMO)13 and 4,4′-bipyridine
N,N′-dioxide (BPDO)14 were synthesized by following the
reported procedures.
BPMO·CPCA. Single crystals of this system were obtained
when methanol solution of equimolar amounts of BPMO and
CPCA was allowed to evaporate at room temperature.
X-ray crystallography
X-ray crystal data were collected on Xcalibur Eos Oxford
Diffraction Ltd. with Mo-Kα radiation (λ = 0.71073 Å). Empirical
absorption correction using spherical harmonics, implemented
in SCALE3 ABSPACK scaling algorithm were applied.15 Struc-
ture solution and refinement were performed with SHELXS16
and SHELXL17 respectively using Olex2-1.1 software package.18
Hydrogen atoms attached to carbon were placed in calculated
position using riding model. All the hydrogen atoms attached
to O atoms were refined with O–H = 0.85 Å and where
the hydrogen atoms attached to N atoms were refined with
N–H = 0.91 Å.
Synthesis of 4,4′-trimethylenebipyridine N-monoxide (TBPO)
TBPO was prepared by following a procedure similar to the
synthesis of BPMO.13 4,4′-trimethylenebipyridine (1 g, 5.05 mmol)
was taken in chloroform solvent (20 ml). To this solution, 70%
m-chloroperbenzoic acid (871.47 mg, 5.05 mmol) in 50 ml
chloroform was added and the resulting solution was allowed
to stir for three days at room temperature. Additional four
more portions of m-chloroperbenzoic acid (134.730 mg,
0.78 mmol) each in chloroform (15 ml) were added after every
24 hours and the reaction was allowed to stir for a total of
seventeen days. The crude mixture was filtered and solvent was
removed in vacuum. TBPO was separated by using column
chromatography and was found to be a yellow hygroscopic
compound. Yield 62%.
Solubility studies
Preparation of standard solution. For preparing the
calibration curve, known concentration of stock solutions
were prepared by taking 4.6 mg (0.299 mmol) of BPY and
5.0 mg (0.299 mmol) of PNBA individually and made up to
500 ml using double distilled water, and for BPDO 5.7 mg
(0.302 mmol) was taken and dissolved in 1 L of water.
Five standard solutions were prepared from each of these
stock solutions by taking 1, 3, 5, 7 and 9 ml from these
solutions and then made up to 10 ml individually by adding
double distilled water and these solutions were used for
UV-Visible experiments.
1H NMR (CDCl3, 400 MHz): δ (ppm) 8.512 (d, J = 5.6 Hz, 2H),
8.142 (d, J = 9 Hz, 2H), 7.101 (d, J = 5.6 Hz, J = 2H),
7.098 (d, J = 9 Hz, 2H), 2.657 (t, J = 7.2 Hz, 2H), 2.637 (t, J =
7.2 Hz, 2H), 1.971 (qn, J = 7.6 Hz, 2H).
Crystallization
TBPO·PNBA. TBPO and PNBA (1 : 1) were dissolved in
methanol solvent. Single crystals were formed after two days
through slow evaporation of the solvent.
TBPO·PCBA. Equimolar amounts of TBPO and PCBA were
dissolved in methanol solvent. Slow evaporation of the solvent
after three days resulted in good quality single crystals.
TBPO·PHBA. 1 : 1 mixture of TBPO and PHBA was dissolved
in a methanol–mesitylene (2 : 1) solvent mixture. The solution
was allowed to evaporate at room temperature and after a
period of eight days, single crystals were obtained.
Preparation of saturated solution. Individual saturated
solutions of BPY (300 mg, 19.20 mmol), PNBA (200 mg,
11.96 mmol), BPDO (500 mg, 26.57 mmol), BPY·PNBA
cocrystal (700 mg, 14.27 mmol), and BPDO·PNBA cocrystal
(700 mg, 13.40 mmol) were prepared by stirring each of the
compounds for 48 hours in 5 ml of double distilled water.
The solutions were then filtered and further diluted by adding
water as follows to study the UV-Visible spectrum.
PNBA. 1 ml saturated solution was taken and made up
to 100 ml.
TBPO·CPCA. Single crystals of this system were obtained
when a methanolic solution of TBPO and CPCA (1 : 1) was
allowed to evaporate at room temperature.
BPY. 0.5 ml of saturated solution was taken and made
up to 100 ml. 30 ml of this solution was further diluted
to 100 ml.
BPMO·PHBA·H2O. BPMO and PHBA (1 : 1) were dissolved
in a 1 : 1 mixture of water and methanol. The solution was
allowed to evaporate slowly at room temperature and
diffraction quality single crystals were obtained after five days.
BPMO·PHBA. 1 : 1 mixture of BPMO and PHBA was
dissolved in ethanol. The solution was allowed to evaporate
slowly at room temperature and diffraction quality single
crystals were obtained after four days.
BPMO·PCA. Equimolar amounts of BPMO and PCA were
dissolved in methanol. The hot solution was allowed to
evaporate slowly at room temperature and diffraction quality
single crystals were obtained after three days.
BPDO. 0.5 ml of saturated solution was taken and made
up to 100 ml. 10 ml of this solution was further diluted to
500 ml.
BPY·PNBA. 0.5 ml saturated solution was taken and made
up to 100 ml.
BPDO·PNBA. 0.5 ml saturated solution was taken and
made up to 200 ml.
Five solutions were prepared from each of the above
mentioned solutions by taking 1, 3, 5, 7 and 9 ml from these
solutions and then made up to 10 ml individually by adding
double distilled water and these solutions were used for
UV-Visible experiments.
4716 | CrystEngComm, 2014, 16, 4715–4721
This journal is © The Royal Society of Chemistry 2014

View Article Online
CrystEngComm
Paper
to mention here that the BPMO·CPCA acid crystal lattice is
noncentrosymmetric and made of closely parallel hydrogen
bonded chains of the highly polar coformers. Therefore, it is
expected to show a good second harmonic generation (SHG)
property. On the other hand, a reverse trend has been
Results and discussion
Crystal structures and hydrogen bonds
In this work we have intended to find out which of the two
groups, pyridyl or pyridyl N-oxide, is a better hydrogen bond
acceptor in their heterosynthons with carboxylic acid group.
Competition experiments could be performed by dissolving
equimolar quantities of an acid, pyridine and pyridine
N-oxide molecules in a suitable solvent to check which
synthon is formed in the resulting cocrystal (Table 1).19 But
there could be a drawback in this process. Apart from the
synthon stability, the solubility also could play a very important
role in the outcome of the crystallization product, which
might mislead the conclusion. Therefore, in our experiments
we have introduced both of the groups, pyridyl as well as the
pyridyl N-oxide, in the same molecule to overcome the solubility
difference of the acceptor moieties.
We have chosen two different types of molecules, BPMO, a
rigid, conjugated, and linear molecule, and TBPO, a flexible,
non-conjugated between the two aryl groups, and bent molecule,
for this study (Scheme 1). On the other hand, we have selected
some simple compounds, including drugs, which contain a
COOH group as hydrogen bond donor (Scheme 1). Then the
occurrence of the heterosynthons and bond distances were
analyzed to understand the most favourable heterosynthon of
the two. Solubility studies using UV absorption experiments on
two cocrystals containing these heterosynthons were also
performed to investigate whether the idea of replacement of
pyridyl entity with the pyridyl N-oxide would give any solubility
advantage in pharmaceutical cocrystal research.
¯
observed in the cocrystals of the BPMO·PHBA·H2O (P1, 1 : 1 : 1)
¯
and BPMO·PCA (P21/n, 1 : 1) systems. Where, the carboxylic
acid groups prefer the pyridyl N-oxide group over the pyridyl
group of the BPMO molecule (Fig. 1g, h). Hence, there are
four carboxyl⋯N-oxide synthons and six carboxyl⋯pyridine
synthons in these eight complexes reported here. Therefore,
the occurrence of the carboxyl⋯pyridine synthons is higher
than the carboxyl⋯N-oxide synthons. On the other hand, the
average O⋯O bond distance (2.561 Å) in the carboxyl⋯N-oxide
synthons is much shorter (by 0.479 Å) than the van der Waals
sum of the oxygens (3.04 Å) compared to the average O⋯N
bond distance (2.633 Å) in the carboxyl⋯pyridine synthons
which is shorter only by 0.437 Å than the van der Waals sum
(3.07 Å) of the oxygen and nitrogen atoms. Hydrogen bond
distances are given in Table 2.
Energy calculation
We also have performed theoretical energy calculation on
these two synthons. Geometry optimization of individual
molecules and their corresponding hydrogen bonded
complexes were performed using M06-2X20 density functional.
M06-2X is shown to be accurate in computing hydrogen
bonding interactions with the mean unsigned error (MUE)
less than 1 kcal mol−1.20 Harmonic vibrational frequencies
were computed and were used for applying zero-point
vibrational energy correction. The DFT calculations using
Gaussian-0921 package with M06-2X/6-31+G(d,p) level of
theory shows that after considering the BSSE and ZPE correc-
tions, the carboxyl⋯N-oxide synthon between the benzoic
acid and pyridine N-oxide (−13.47 kcal mol−1) is slightly more
stable than the carboxyl⋯pyridine synthon between benzoic
acid and pyridine molecules (−11.84 kcal mol−1). According to
the independent studies by Berthelot22 and Nangia,23 the
pyridine N-oxide group is shown to be a better hydrogen
bond acceptor than the pyridyl N when the donor group is
phenolic OH or carboxamide respectively.
A 1 : 1 cocrystallization of the TBPO with PNBA and PCBA
molecules resulted into the 1 : 2 cocrystals of the TBPO·PNBA
¯
acid (P1) and TBPO·PCBA acid (P21/c) systems. The carboxylic
groups are hydrogen bonded to both of the acceptors of the
TBPO molecule (Fig. 1a, b). The strong hydrogen bond
accepting nature of the pyridyl and pyridyl N-oxide groups
and due to decrease in selectivity owing to the presence of
strong electron withdrawing groups (nitro or cyano) in the
acid molecule, the resultant complex ratio is 1 : 2 rather than
the intended 1 : 1 product. Hence no preference, based on the
occurrence of the synthons, could be observed in these two
experiments. Therefore, we have introduced an electron
donating protic functional group (OH) in the acid molecule,
expecting that it would increase the selectivity by decreasing
the acidity of the carboxylic acid group as well as being rela-
tively a weaker donor it would satisfy the weaker acceptor
through hydrogen bond formation. Both of the 1 : 1 complex
of TBPO·PHBA and 1 : 2 complex of TBPO·CPCA crystallize in
Solubility study
The main aim of the solubility study in this case was to
compare the solubility of the acid in acid·pyridine and
acid·pyridine N-oxide complexes. We prepared 1 : 2 complexes
of PNBA with BPY and BPDO.24 In both the complexes the
acid group forms heterosynthons with pyridine or pyridine
N-oxide hydrogen bond acceptor. The usual way to find out
the concentration of a compound in a saturated solution
using Lambert–Beers law is by calculating the extinction
coefficient (ε) of the compound from the absorption vs.
concentration plots of some solutions with known concentration
of the compound (standard solutions) and then by measuring
¯
P1 space group. The carboxylic acid groups of the PHBA and
the CPCA in these complexes prefer hydrogen bonding with
the pyridyl group, while the phenolic O–H groups form
hydrogen bonds with the pyridyl N-oxide group of the TBPO
molecule (Fig. 1c, d). Similar results were also observed in
the cocrystals of these two molecules with BPMO (Fig. 1e, f).
These two 1 : 1 complexes of BPMO·PHBA and BPMO·CPCA
¯
crystallize in P1 and Cc space groups respectively. It is worth
This journal is © The Royal Society of Chemistry 2014
CrystEngComm, 2014, 16, 4715–4721 | 4717

View Article Online
Paper
CrystEngComm
4718 | CrystEngComm, 2014, 16, 4715–4721
This journal is © The Royal Society of Chemistry 2014

View Article Online
CrystEngComm
Paper
Scheme 1 Compounds used in the complex formation in this study.
the absorption of the saturated solution.25 Unfortunately, the
absorbance of the acid and the co-former in each of these two
complexes were overlapping (Fig. 2) and hence solubility of
the acid in the saturated solutions could not be determined
by the usual way, i.e. from the absorption at λmax of the
saturated solutions. There are some experimental techniques
e.g. NMR, HPLC, etc. used to find out the concentration of a
component in saturated solution in these cases.26 But these
methods involve expensive equipment, hazardous solvents
etc. Here, we have used a simple and less expensive method,
explained below, to resolve the overlapping problem.
A saturated solution of the PNBA·BPY complex was diluted
to five different concentrations and their absorptions were
plotted against wavelength. Similarly, five standard solutions
were prepared from each of the individual compounds
and absorption vs. wavelength was plotted. Then two wave-
lengths, λ1 (260 nm) and λ2 (274 nm), were selected at which
absorptions vs. concentration plots for the two individual
compounds solutions as well as the saturated cocrystal
solution show good linear fittings. Two extinction coefficients,
ε1′ and ε2′ have been calculated at these two wavelengths, λ1
and λ2, respectively from the absorption vs. concentration
plots of standard solutions of PNBA. Similarly, two extinction
coefficients, ε1″ and ε2″ have been calculated at those two
wavelengths, λ1 and λ2, from the plots of standard solutions of
BPY. Then absorptions, A1 and A2 have been measured from
the linear absorption vs. concentration plots for the saturated
solution of the PNBA·BPY complex at λ1 and λ2 respectively.
Solving two linear equations (eqn (1) and (2)) produces
the values of the concentrations of PNBA (c′) and BPY (c″) in
the particular diluted solutions prepared from the saturated
solution of the complex.
A1 = ε′1c′ + ε1″c″ at λ1 nm …
A2 = ε′2c′ + ε2″c″ at λ2 nm …
(1)
(2)
In a similar way, the concentrations of PNBA and BPDO in
the saturated solution of the 1 : 2 complex of PNBA·BPDO
have been calculated at 293 nm and 298 nm. Calculation
Fig. 1 Hydrogen bond interactions in (a) TBPO·PNBA, (b) TBPO·PCBA,
(c) TBPOP·PHBA, (d) TBPO·CPCA, (e) BPMO·PHBA, (f) BPMO·CPCA, (g)
BPMO·PHBA·H2O, and (h) BPMO·PCA.
This journal is © The Royal Society of Chemistry 2014
CrystEngComm, 2014, 16, 4715–4721 | 4719

View Article Online
Paper
CrystEngComm
Table 2 Hydrogen bond parameters
Hydrogen bonds
d/Å
D/Å
θ/°
TBPO·PNBA
TBPO·PCBA
O1–H1⋯O5
O1–H1⋯N2
O6–H6⋯N3
O1–H1⋯O5
O1–H1⋯N4
O3–H3A⋯N3
O1–H1⋯N1
O3–H3⋯O4
O1–H1⋯O5
N3–H3⋯O4
O3–H3B⋯O6
O6–H6A⋯O7
O6–H6A⋯N4
O1–H1⋯N1
O3–H3⋯O4
O1–H1⋯N1
O3–H3⋯O4
O1–H1⋯O4
O3–H3⋯O5
O5–H5A⋯O4
O5–H5B⋯N1
O1–H1⋯O4
O3–H3⋯N1
1.67(3)
2.55(3)
1.77(4)
1.55(2)
2.51(2)
1.76(2)
1.79(3)
1.86(3)
1.62(3)
1.80(6)
1.90(4)
1.66(7)
2.54(8)
1.76(3)
1.75(2)
1.66(2)
1.76(2)
1.75(2)
1.80(2)
1.88(2)
2.00(2)
1.74(2)
1.83(2)
2.528(3)
3.364(4)
2.624(5)
2.531(3)
3.543(3)
2.620(3)
2.644(4)
2.676(4)
2.491(5)
2.687(6)
2.716(7)
2.494(7)
3.281(7)
2.620(4)
2.596(4)
2.574(2)
2.611(2)
2.624(2)
2.668(2)
2.752(2)
2.834(2)
2.570(2)
2.689(2)
172(3)
159(2)
176(4)
155(1)
174(1)
173(3)
176(2)
159(3)
175(8)
166(7)
162(8)
167(9)
146(7)
175(3)
175(2)
174(2)
175(2)
169(2)
172(2)
175(2)
166(2)
165(3)
175(2)
TBPO·PHBA
TBPO·CPCA
BPMO·PHBA
BPMO·CPCA
BPMO·PHBA·H2O
BPMO·PCA
shows that the concentration of the acid in its saturated solu-
tion is 2.3 × 10−3 M, whereas it is 3.4 × 10−3 M and 4.1 × 10−3
M
in the PNBA·BPY and PNBA·BPDO complexes respectively.
On the other hand, the solubility of BPY in its saturated
solution is 3.3 × 10−2 M and that in the PNBA·BPY complex is
8.1 × 10−3 M. Similarly, the solubility of BPDO in its saturated
solution is 2.4 × 10−1 M, but that in the saturated solution of
the PNBA·BPDO complex is 8.8 × 10−3 M. A comparison of
the concentrations of the acid in its saturated solution and in
the saturated solutions of the two complexes suggests that
solubility of PNBA increases by ~1.5 times in the PNBA·BPY
complex and by ~1.8 times in the PNBA·BPDO complex. It
has been noticed that owing to the higher polarity, the BPDO
compound is ~7 times more soluble than BPY. Therefore, the
ability of BPDO to retain the acid compound in solution is
more than that of BPY.
Fig. 2 Absorbance vs. wavelength plots for (a) BPY (blue), PNBA (red),
BPY·PNBA (magenta) complex and (b) BPDO (blue), PNBA (red),
BPDO·PNBA complex (magenta).
of the pyridine N-oxide⋯acid complex could be due to the
much higher solubility of the pyridine N-oxide compound
compared to that of the corresponding pyridine compound.
This synthon preference and increase in solubility suggest
that pyridine N-oxide compound could be a better choice than
the pyridine compound in the preparation of pharmaceutical
cocrystals with acid compounds.
Conclusions
In this work we have studied a series of acid⋯pyridine and
acid⋯pyridine N-oxide complexes. The propensity of occurrence
of the acid⋯pyridine synthon is more than that of
acid⋯pyridine N-oxide synthon, but bond distance analysis
shows that the latter is relatively a stronger synthon than the
former. Energy calculation also suggests that the acid⋯pyridine
N-oxide is slightly stronger than the acid⋯pyridine synthon.
The higher propensity of the acid⋯pyridine synthon could be
attributed to the salt formation tendency of this particular
synthon. The solubility study shows that the acid compound is
more soluble in the presence of pyridine N-oxide compared to
in the presence of a pyridine compound. The higher solubility
Acknowledgements
B.K.S. thanks Council of Scientific and Industrial Research,
India (no. 02(0026)/11/EMR-II) for financial support, DST-FIST
for single crystal X-ray Diffractometer and CIF, Pondicherry
University for NMR facility, V.G.S. thanks UGC and M. A. B.
thanks Pondicherry University for a fellowship.
4720 | CrystEngComm, 2014, 16, 4715–4721
This journal is © The Royal Society of Chemistry 2014

View Article Online
CrystEngComm
Paper
P. Sanphui, N. R. Goud, U. B. R. Khandavilli and A. Nangia,
Cryst. Growth Des., 2011, 11, 4135; S. Aitipamula, A. B. H. Wong,
P. S. Chow and R. B. H. Tan, CrystEngComm, 2012, 14, 8515.
12 C. B. Aakeroy and D. J. Salmon, CrystEngComm, 2005, 7, 439;
L. S. Reddy, N. J. Babu and A. Nangia, Chem. Commun.,
2006, 1369; A. V. Trask, W. D. S. Motherwell and W. Jones,
Cryst. Growth Des., 2005, 5, 1013; T. R. Shattock, K. K. Arora,
P. Vishweshwar and M. J. Zaworotko, Cryst. Growth Des.,
2008, 8, 4533; S. Roy and K. Biradha, Cryst. Growth Des.,
2013, 13, 3232; C. B. Aakeroy, A. M. Beatty and B. A. Helfrich,
J. Am. Chem. Soc., 2002, 124, 14425.
13 D. J. Hoffart, N. C. Habermehl and S. J. Loeb, Dalton Trans.,
2007, 2870.
14 P. G. Simpson, A. Vinciguerra and J. V. Quagliano, Inorg.
Chem., 1963, 2, 282.
15 CrysAlisPro, Version 1.171.33.66; Oxford Diffraction Ltd.:
Abingdon, U.K., 2010.
16 G. M. Sheldrick, SHELXS, Acta Crystallogr., Sect. A: Found.
Crystallogr., 2008, 64, 112.
Notes and references
1 G. R. Desiraju, Angew. Chem., Int. Ed. Engl., 1995, 34, 2311;
G. R. Desiraju, J. Am. Chem. Soc., 2013, 135, 9952; A. Nangia,
Cryst. Growth Des., 2008, 8, 1079; M. L. Cheney, D. R. Weyna,
N. Shan, M. Hanna, L. Wojtas and M. J. Zaworotko, Cryst.
Growth Des., 2010, 10, 4401; S. Basavoju, D. Bostrom and
S. P. Velaga, Cryst. Growth Des., 2006, 6, 2699; P. Sanphui,
S. S. Kumar and A. Nangia, Cryst. Growth Des., 2012, 12, 4588;
P. M. Bhatt, Y. Azim, T. S. Thakur and G. R. Desiraju, Cryst.
Growth Des., 2009, 9, 951; S. Roy, R. Quiñones and
A. J. Matzger, Cryst. Growth Des., 2012, 12, 2122; D. Maddileti,
S. K. Jayabun and A. Nangia, Cryst. Growth Des., 2013, 13,
3188; P. Vishweshwar, J. A. McMahon, J. A. Bis and
M. J. Zaworotko, J. Pharm. Sci., 2006, 95, 499; G. R. Desiraju,
Angew. Chem., Int. Ed., 2007, 46, 8342; G. Bolla, S. Mittapalli
and A. Nangia, CrystEngComm, 2014, 16, 24; S. Aitipamula,
A. B. H. Wong, P. S. Chow and R. B. H. Tan, CrystEngComm,
2013, 15, 5877.
2 G. R. Desiraju, Chem. Commun., 1997, 1476; R. Banerjee,
R. Mondal, J. A. K. Howard and G. R. Desiraju, Cryst. Growth
Des., 2006, 6, 999; V. R. Thalladi, B. S. Goud, V. J. Hoy, F. H. Allen,
J. A. K. Howard and G. R. Desiraju, Chem. Commun., 1996, 401;
S. Bhattacharya, J. Stojakovi, B. K. Saha and L. R. MacGillivray,
Org. Lett., 2013, 15, 744; M. Garai, R. Santra and K. Biradha,
Angew. Chem., Int. Ed., 2013, 52, 5548; S. Subramanian and
M. J. Zaworotko, Coord. Chem. Rev., 1994, 137, 357.
3 K. M. Dethlefs and P. Hobza, Chem. Rev., 2000, 100, 143;
G. R. Desiraju and T. Steiner, In The Weak Hydrogen Bond in
Structural Chemistry and Biology, Oxford University Press,
1999; R. Banerjee, G. R. Desiraju, R. Mondal and
J. A. K. Howard, Chem.–Eur. J., 2004, 10, 3373; S. K. Nayak,
M. K. Reddy, T. N. Guru Row and D. Chopra, Cryst. Growth
Des., 2011, 11, 1578; A. Nangia, CrystEngComm, 2002, 4, 93;
R. Santra, K. Banerjee and K. Biradha, Chem. Commun.,
2011, 47, 10740; S. Bhattacharya and B. K. Saha, Cryst.
Growth Des., 2013, 13, 3299; G. R. Desiraju, Acc. Chem. Res.,
1991, 24, 290; P. Munshi, K. N. Venugopala, B. S. Jayashree
and T. N. Guru Row, Cryst. Growth Des., 2004, 4, 1105.
4 M. C. Etter, Acc. Chem. Res., 1990, 23, 120.
5 C. B. Aakeröy, M. Fasulo, N. Schultheiss, J. Desper and
C. Moore, J. Am. Chem. Soc., 2007, 129, 13772.
6 C. B. Aakeröy, S. Panikkattu, P. D. Chopade and J. Desper,
CrystEngComm, 2013, 15, 3125.
7 F. Zordan, S. L. Purver, H. Adams and L. Brammer,
CrystEngComm, 2005, 7, 350.
8 B. Sarma, N. K. Nath, B. R. Bhogala and A. Nangia, Cryst.
Growth Des., 2009, 9, 1546.
9 S. Ghosh, P. P. Bag and C. M. Reddy, Cryst. Growth Des.,
2011, 11, 3489.
10 B. Sridhar, J. Nanubolu and K. Ravikumar, CrystEngComm,
2012, 14, 7065.
11 M. K. Stanton, S. Tufekcic, C. Morgan and A. Bak, Cryst.
Growth Des., 2009, 9, 1344; M. K. Stanton and A. Bak, Cryst.
Growth Des., 2008, 8, 3856; L. Rajput, P. Sanphui and
G. R. Desiraju, Cryst. Growth Des., 2013, 13, 3681;
17 G. M. Sheldrick, SHELXL, Acta Crystallogr., Sect. A: Found.
Crystallogr., 2008, 64, 112.
18 O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard
and H. Puschmann, OLEX2: A complete structure solution,
refinement and analysis program, J. Appl. Crystallogr., 2009,
42, 339.
19 E. Corradi, S. V. Meille, M. T. Messina, P. Metrangolo and
G. Resnati, Angew. Chem., Int. Ed., 2000, 39, 1782.
20 Y. Zhao and D. G. Truhlar, Theor. Chem. Acc., 2008, 120, 215.
21 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone,
B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng,
J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao,
H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin,
V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari,
A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi,
N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross,
V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts,
R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli,
J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski,
G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich,
A. D. Daniels, Ö. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski,
and D. J. Fox, Gaussian, Gaussian, Inc., Wallingford CT, 2009.
22 C. Laurence and M. Berthelot, Perspect. Drug Discovery Des.,
2000, 18, 39.
23 L. S. Reddy, N. J. Babu and A. Nangia, Chem. Commun.,
2006, 1369.
24 J. R. Bowers, G. W. Hopkins, G. P. A. Yap and K. A. Wheeler,
Cryst. Growth Des., 2005, 5, 727.
25 T. Higuchi and K. A. Connors, Adv. Anal. Chem. Instrum.,
1965, 4, 117; N. R. Goud, K. Suresh and A. Nangia, Cryst.
Growth Des., 2013, 13, 1590.
26 M. Lin, M. Tesconi and M. Tischler, Int. J. Pharm., 2009, 47,
369; D. B. Albert and C. S. Martens, Mar. Chem., 1997, 56, 27.
This journal is © The Royal Society of Chemistry 2014
CrystEngComm, 2014, 16, 4715–4721 | 4721