Capturing the structural diversification upon thermal desolvation of a robust metal organic framework via a single-crystal-to-single-crystal transformation

Article abstract of DOI:10.1039/c5ce01116g

Using a new mixed polypyridyl-carboxylate ligand, a 2D neutral robust framework of Zn(ii), {[Zn(bpaipa)]·DMF·2H₂O}_n (1) (where H₂bpaipa = 5-(bis(pyridin-2-ylmethyl)amino)isophthalic acid), has been synthesized under solvot

Full text of DOI:10.1039/c5ce01116g

CrystEngComm
View Article Online
View Journal
COMMUNICATION
Capturing the structural diversification upon
thermal desolvation of a robust metal organic
framework via a single-crystal-to-single-crystal
transformation†
Cite this: DOI: 10.1039/c5ce01116g
Received 8th June 2015,
Accepted 21st July 2015
DOI: 10.1039/c5ce01116g
*
Sandeep Kumar and Sanjay K. Mandal
www.rsc.org/crystengcomm
Using a new mixed polypyridyl–carboxylate ligand, a 2D neutral
robust framework of ZnIJII), {[ZnIJbpaipa)]·DMF·2H2O}n (1) (where
H2bpaipa = 5-IJbisIJpyridin-2-ylmethyl)amino)isophthalic acid), has
been synthesized under solvothermal conditions in 71% yield. It
undergoes single-crystal-to-single-crystal transformation upon
thermal desolvation without a change in the topology of the
framework where the desolvated structure shows an orientation
change of an uncoordinated carboxylate oxygen atom and the
pyridyl groups of the ligand within the pores. Both structures have
been determined by single crystal X-ray analysis. Its high thermal
stability (>350 °C) and framework integrity towards many solvents
are also demonstrated by variable temperature powder X-ray dif-
fraction and thermogravimetric analysis.
within the frameworks are filled with solvent molecules.2,3 In
this respect, removal or exchange of guest molecules in the
host assemblies through solid-state transformations, such as
single-crystal-to-single-crystal transformation, is a difficult but
achievable route, where the formation of a stable porous
material is unique. If this structural transformation is revers-
ible in nature, then investigation of the desolvated and
resolvated species not only allows one to understand their for-
mation but more importantly provides an opportunity to use
them in various applications ranging from molecular recogni-
tion and separation to gas storage and sensing.1c However,
the daughter crystals obtained from the desolvation/
resolvation process are seldom found to be suitable for single
crystal structure determination.6–8,9a
In recent years, various strategies for the rational design of
metal organic frameworks (MOFs), also known as porous
coordination polymers (PCPs), have evolved due to their
structural diversity and intriguing molecular topology and
more importantly because of their potential applications in
the fields of gas storage, separation, catalysis, magnetism,
drug delivery, etc.1–5 One of the key features of these
frameworks is their permanent porosity demonstrating their
viability in certain applications. These frameworks are
constructed from a variety of metal ions/clusters (as nodes)
and multitopic organic ligands (as linkers). Through
judicious choice of the components in forming such
frameworks, it is possible in principle to generate materials
with tunable structures and properties. The pore size and
chemical functionality of a wide variety of open frameworks
can be modulated by the nature of the linkers. Based on their
synthesis via a one-pot self-assembly process under hydro/
solvothermal conditions, most of the time the available pores
As our effort to contribute to this field of research, we
have utilized
a three-component self-assembly approach
under ambient as well as hydrothermal conditions where the
importance of the ancillary ligands (mostly tri-, tetra- and
hexadentate polypyridyl ligands) as well as the multitopic
linkers (mostly carboxylates) is demonstrated.9 In continua-
tion of our work, we now focus on the mixed polypyridyl–car-
boxylate functionalities in a single organic component to
temporally connect with numerous di- and trivalent metal
ions. Herein, we report our effort in using a new ligand
H2bpaipa (where H2bpaipa
=
5-IJbisIJpyridin-2-ylmethyl)-
amino)isophthalic acid) to make a 2D robust neutral frame-
work of ZnIJII), {[ZnIJbpaipa)]·DMF·2H2O}n (1), under
solvothermal conditions. Like others, we targeted this frame-
work for gas and vapor adsorption studies with standard
pretreatment of the sample at a temperature (140 °C) close to
the boiling point of the solvent under dynamic vacuum con-
ditions for 24 h; however, preliminary but reproducible gas
adsorption studies indicating much lower than expected
values for nitrogen and methane (see Fig. S1, ESI†) prompted
us to look into the desolvated species more carefully via
single-crystal-to-single-crystal transformation for any struc-
tural change due to this pretreatment. Based on the single
crystal structure of the desolvated species, {[ZnIJbpaipa)]}n (2),
Department of Chemical Sciences, Indian Institute of Science Education and
Research Mohali, Sector 81, Manauli PO, S.A.S. Nagar, Mohali 140306,
Punjab, India. E-mail: sanjaymandal@iisermohali.ac.in
† Electronic supplementary information (ESI) available: Crystallographic data
CCDC 1405287–1405288. Scheme 1, Fig. S1–S13 and Tables S1 and S2. See DOI:
10.1039/c5ce01116g.
This journal is © The Royal Society of Chemistry 2015
CrystEngComm

View Article Online
Communication
CrystEngComm
it is clearly understood that there is no change in the topol-
ogy of the framework but an orientation change of an
uncoordinated carboxylate oxygen atom and the pyridyl
groups of the ligand within the pores has occurred reducing
the available pore size. Therefore, this finding is very impor-
tant in undertaking such adsorption studies, particularly
when the crystal structure of the desolvated species is diffi-
cult to obtain as mentioned above and only a few reports are
available in the literature;6–8,9a most of the time, it is
assumed on the basis of powder X-ray data that there is no
change in the framework due to pretreatment of a sample for
gas and vapor adsorption studies. We also demonstrate the
high thermal stability (>350 °C) and resistance to various
organic solvents of 1 through variable temperature powder
X-ray diffraction and TGA.
Compound 1 was synthesized via the solvothermal reac-
tion of ZnIJOAc)2·2H2O and H2bpaipa in a mixture of DMF
and water (1 : 1 ratio) with an excellent yield of 71%, as
shown in Scheme 1 (for further details see the experimental
section and Scheme S1, ESI†). In its FTIR spectrum (Fig. S2,
ESI†), the asymmetric and symmetric stretching bands of
the carboxylate group in the ligand appear at 1633 cm−1 and
1345 cm−1 (Δν = νasym − νsym = 288 cm−1), respectively, indi-
cating a monodentate binding mode to ZnIJII),10 which is
confirmed in its crystal structure discussed below. A peak at
1662 cm−1 indicates the presence of the lattice DMF molecule.
Compound 1 crystallizes in the monoclinic P21/n space
group (see Table S1, ESI†).11–14 The asymmetric unit consists
of one ZnII, one bpaipa ligand and lattice solvents (one mole-
cule of DMF and two molecules of water). Thus, the overall
framework is neutral. As shown in Fig. S3 (ESI†), the metal
lies in a distorted square-pyramidal environment formed by
three nitrogens of the ligand – two pyridyl nitrogens (dis-
tances: Zn–Npy, 2.089(3) Å and 2.059(3) Å) and one alkyl nitro-
gen (distance: Zn–Nalkyl, 2.400(3) Å) – and two oxygens of two
different carboxylates from two different ligands (distances:
2.062(2) Å and 1.989(2) Å). The degree of distortion from the
ideal geometry is reflected in the bond angles around the
0.22 for 1. Both carboxylate groups bind in a monodentate
fashion. The selected bond distances and angles for 1 are
listed in Table S1.† These Zn–N/O distances are very similar
to those reported for MOFs with similar ligands.16 With such
metal–ligand connectivity, an overall 2D framework is formed
in 1 having pores with dimensions of 14.715(2) Å × 9.586(2) Å
(defined by the distance between corner Zn2+ centers) as
shown in Fig. 1, top. Considering the added methylpyridyl
group in the H2bpaipa ligand compared to its parent Schiff
base or reduced Schiff base ligands reported by other
groups,16 the coordination environment of ZnII in 1 is differ-
ent with respect to its geometry and has no coordinated sol-
vent molecule.16 A schematic representation of 1 without
these solvent molecules (see Fig. S4, ESI†) provides the shape
of the large pores; PLATON (ref. 17) analysis shows that
about 33% of the unit cell volume is occupied by the solvent
molecules. Simplified topological analysis by TOPOS (ref. 18)
on 1 revealed that it is a uninodal 5-c net with the Schläfli
symbol {3^3.4^3.5^4} (Fig. S5, ESI†). The lattice water
metal center
(O1″–Zn1–N3
107.49IJ11)°,
N2–Zn1–N3
150.47IJ11)°, O1″–Zn1–N1 130.53IJ10)°, etc.). The τ parameter,
which is an indicator15 of the deviation from the ideal
square-pyramidal (τ = 0) and trigonal bipyramidal (τ = 1)
geometries of five-coordinated metal centers, is found to be
Fig. 1 Top: Crystal structure of 1 showing a large pore without the
solvent molecules; hydrogen atoms are not included for clarity.
Bottom: Display of DMF and H2O lattice solvent molecules (in space
filling representation) in the pores of 1.
Scheme 1 Solvothermal synthesis of 1.
CrystEngComm
This journal is © The Royal Society of Chemistry 2015

View Article Online
CrystEngComm
Communication
molecules form a zigzag chain with the coordinated oxygens
of the carboxylate groups and the DMF molecules situated in
the large pores as shown in the space filling representation
(Fig. 1, bottom). Based on these hydrogen bonding interac-
tions, a 3D network is established in 1. The phase purity of
the bulk 1 was studied by powder X-ray diffraction studies
which showed good agreement with simulations based on
the single crystal structure (see Fig. S6, ESI†).
unit cell parameters and volume of 2 compared to 1. While
the length of both b and c axes was shortened by 2 Å in each
case, the value of β increased by 2.3°. Also, the reduction of
the unit cell volume (567.3 Å3; 24.7%) at 100 K (similar values
are obtained at 200 K and 296 K) is much more than
expected for the loss of four DMF and eight water molecules
per unit cell. This is unexpected unless other changes
occurred due to the desolvation process. Such an event with
24.7% reduction in cell volume can be compared to a rele-
vant case7d with 35.1% reduction in cell volume.
In order to understand the thermal stability and its struc-
tural
variation
as
a
function
of
temperature,
thermogravimetric analysis (TGA) was conducted for the
single-phase polycrystalline sample of 1. The TGA scan shown
in Fig. S7 (ESI†) between 25 and 500 °C indicates that the
continuous loss of all solvent molecules occurs up to 200 °C
and then it becomes stable up to 350 °C (vide infra), after
which subsequent decomposition of the product(s) occurs.
This desolvation process (see Fig. S8, ESI†) was further moni-
tored with variable temperature FTIR data (see Fig. S9, ESI†)
which suggested that a complete loss of all solvent molecules
can be achieved at 170 °C based on the disappearance of the
peak at 1662 cm−1 due to loss of DMF. Thus, the single crys-
tals of 1 were heated at 140 °C under dynamic vacuum condi-
tions using a vacuum oven for 1 h.
A single crystal from the batch used for the variable tem-
perature FTIR experiment was chosen for single crystal struc-
ture analysis of the desolvated species, which was confirmed
to be {[ZnIJbpaipa)]}n (2). Compound 2 also crystallizes in the
monoclinic P21/n space group (see Table S1, ESI†)11–14 with
the same asymmetric unit found in 1 except that there were
no solvent molecules and thus forms a 2D framework (see
Fig. S10, ESI†). However, there are noticeable changes in the
This can be understood if the overall change of the frame-
work shown in Fig. 2c and f is carefully considered. With a
close-up view (Fig. 2b and d) of the pores in 1 and 2, it is
clear that the changes in positions of the uncoordinated oxy-
gen O2 of a carboxylate group and one of the pyridyl groups
(that containing N2) of the ligand are the effects of the
desolvation process. This has caused a change around the
metal center which is reflected by a large shift in the angle
between the planes defined by the metal center and carboxyl-
ate groups in the ligand IJ32.75IJ3)° in 1 and 55.51IJ3)° in 2), as
shown in Fig. 2a and e. Like 1, ZnII in 2 lies in a distorted
square-pyramidal environment formed by three nitrogens of
the ligand – two pyridyl nitrogens and one alkyl nitrogen –
and two oxygens of two different monodentate carboxylates
from two different ligands. The τ parameter is found to be
0.15 for 2. Comparing the bond distances and angles around
ZnII for 2 (listed in Table S2, ESI†) with those for 1, it can be
noted that except one of the Zn–Npy (Zn1–N2) distances (the
one which moved further into the pores) which lengthened
by 0.06(2) Å, all other distances become shorter by 0.05IJ2)–
0.06IJ2) Å in 2. For the same reason, the angles involving
Fig. 2 Schematic representation of the desolvation process of 1 to 2: an overall change in the network is shown in (c) and (f) while the change
within the large pore due to loss of solvent molecules is shown in (b) and (d) and the change around the metal centers is shown in (a) and (e).
This journal is © The Royal Society of Chemistry 2015
CrystEngComm

View Article Online
Communication
CrystEngComm
Fig. 3 Change in the orientation of an oxygen atom (O2) of the
carboxylate group and pyridyl groups of the ligand within the pore
during the desolvation of 1 to 2. Symmetry codes for equivalent
positions are: ′ = −x, −y + 1, −z + 2 for 1 and ′ = −x, −y, −z + 1 for 2.
Fig. 4 Variable temperature powder diffraction patterns (top: heating
from 25 °C to 350 °C; bottom: cooling back to 25 °C) indicating
retention of crystallinity in 1 (due to loss of lattice solvents) up to 350 °C.
carboxylate oxygen O1 (the other oxygen in this group is O2)
and pyridyl nitrogen N2 are affected the most. Upon further
consideration of this structural change as shown in Fig. 3, it
can be seen that the O2 atom moved into the pores for the
conversion of 1 to 2 (O2⋯O2′ distance: 9.002(2) Å in 1 vs.
6.901(2) Å in 2). This has resulted in lower pore accessibility
in 2 compared to 1 even though the pore dimensions in 2 are
15.565(2) Å × 8.72(2) Å (based on the distance between corner
Zn2+ centers, as was considered for 1). The topology of the
framework in 2 remained the same as that of 1 (see Fig. S11, ESI†).
Based on the distinct thermal behavior, compound 1 was
further investigated to provide insight into its crystalline
properties at different temperatures (with a heating profile
from 25 °C to 350 °C and then cooling back to 25 °C). As can
be seen from Fig. 4 where the patterns for each step are
found to be similar except for a small change due to loss of
solvent molecules, compound 1 retains its crystallinity and
overall structure up to 350 °C which corroborates well with
the thermogravimetric analysis.
losing its crystallinity. The TGA data (Fig. S12, ESI†) for four
solvates indicate that methanol was absorbed the most (2.5
molecules) while toluene the least (0.14 molecule), per mole-
cule of the framework. This observation will be exploited to
undertake other host–guest chemistry studies in the future.
In conclusion, we have designed and synthesized a new
mixed polypyridyl–carboxylate ligand, 5-IJbisIJpyridin-2-
ylmethyl)amino)isophthalic acid to construct a 2D neutral
In order to demonstrate the stability of 1 in different
organic solvents, six sets of crystals of 2 generated through
the desolvation of 1 as described above and confirmed by
TGA were immersed in different solvents (acetonitrile,
dichloromethane, hexane, methanol, tetrahydrofuran and tol-
uene) for two days and filtered to obtain various solvates of
1. As can be seen from Fig. 5, the PXRD patterns of all these
solvates are similar to each other and match well with that of
1. This confirms that the framework in 1 is robust enough to
undergo such
a
desolvation/resolvation process without
Fig. 5 PXRD patterns of various solvates of 1.
CrystEngComm
This journal is © The Royal Society of Chemistry 2015

View Article Online
CrystEngComm
Communication
robust framework of ZnIJII), {[ZnIJbpaipa)]·DMF·2H2O}n (1),
under hydrothermal conditions. Upon thermal desolvation of
1 via single-crystal-to-single-crystal transformation without
loss of the framework topology, the resulting structure shows
an orientation change of an oxygen atom through the rota-
tion of coordinated carboxylate groups and one of the pyridyl
groups within the pores. Based on the PXRD and TGA data,
the parent compound shows high thermal stability and
appears to be stable in different organic solvents. Further
development of several new derivatives of 1 to study their
gas/vapor adsorption and sensing applications is in progress.
Yield: 71% (38 mg) based on Zn2+ ion. Anal. Calc. (%) for
C23H30N4O9Zn (MW 571.89): C, 48.30; H, 5.29; N, 9.80. Found:
C, 47.86; H, 4.67; N, 8.97. Despite our numerous efforts, the
CHN data fit with one DMF and four water molecules. Selected
FTIR peaks (KBr, cm−1): 3344(br), 1662(m), 1633(s), 1607(s),
1567(s), 1443(s), 1345(s), 1297(m), 783(m), 725(m).
Acknowledgements
Sandeep Kumar is grateful to MHRD, India for a research fel-
lowship. The authors would like to thank Dr. Sadhika Khullar
for conducting the gas adsorption study and providing critical
review of the manuscript. Funding for this work was provided
by IISER, Mohali. The X-ray and NMR facilities at IISER,
Mohali are gratefully acknowledged.
Experimental section
Synthesis of H2bpaipa
In step 1, 5-IJbisIJpyridin-2-ylmethyl)amino)isophthalic acid
was prepared with some modifications in the reported proce-
dure.19 To a methanolic solution of 5-aminoisophthalic acid
(1.81 g (10 mmol) in 10 mL of methanol) in a 50 mL RBF, tri-
ethylamine (2 mL) was added and stirred for 15 min. Subse-
quently, 2-pyridinecarboxaldehyde (0.98 mL, 10 mmol) was
added and stirred for 8 h. An excess of sodium borohydride
(2 equiv.) was added slowly to the above solution at 0 °C and
stirred for another 10 h. Upon evaporation of most of the sol-
vent under reduced pressure, the resulting slurry was poured
into 20 mL of ice cold water followed by addition of a few
drops of acetic acid to make the pH 5–6. A yellowish white
precipitate (1.35 g, 52%) was isolated after evaporation of the
solvent. Its melting point and 1H NMR data were matched
with the literature values, confirming its identity and purity.
This was used in the next step without any purification.
In step 2, to an aqueous solution (8 mL) of the reduced
Schiff base obtained in step 1 (0.5 g, 0.002 mol), picolyl chlo-
ride hydrochloride (0.32 g, 0.002 mol) was added and the
mixture was stirred for 5 min. After adding sodium hydroxide
solution (0.16 g in 1 mL of water) dropwise over a period of
20 min, the mixture was stirred for 24 h at room tempera-
ture. The aqueous reaction mixture was washed 3–4 times
with chloroform followed by the addition of 1 mL of dil. HCl.
A yellowish solid was formed. Further work-up to remove
NaCl using dry MeOH provided the desired product. Yield:
583 mg (85%). See Scheme S1, Fig. S13 and S14, ESI.† 1H
NMR (D2O): δ 8.33 (d, 2H), 7.65 (d, 2H), 7.48 (s, 1H), 7.21 (d,
2H), 7.19 (d, 2H), 4.76 (s, 4H). 13C NMR (D2O): δ 169.03,
152.29, 147.27, 146.13, 141.94, 131.88, 126.06, 125.23, 121.90,
118.39, 52.26. HRMS (ESI-TOF): m/z calcd for M + H+,
364.1252; found, 364.1284.
Notes and references
1 (a) J. L. C. Rowsell and O. M. Yaghi, Angew. Chem., Int. Ed.,
2005, 44, 4670; (b) X. Lin, J. Jia, X. Zhao, K. M. Thomas, A. J.
Blake, G. S. Walker, N. R. Champness, P. Hubberstey and M.
Schröder, Angew. Chem., Int. Ed., 2006, 45, 7358; (c) S.
Kitagawa, R. Kitaura and S. Noro, Angew. Chem., Int. Ed.,
2004, 43, 2334.
2 See issue no. 5 of the 38th volume of Chem. Soc. Rev.
(2009).
3 See issue no. 2 of the 112th volume of Chem. Rev. (2012).
4 Representative examples: (a) R. E. Morris, Nat. Chem.,
2011, 3, 347; (b) J. R. Li and H. C. Zhou, Nat. Chem., 2010, 2,
893; (c) R. Makiura, S. Motoyama, Y. Umemura, H.
Yamanaka, O. Sakata and H. Kitagawa, Nat. Mater., 2010, 9,
565; (d) S. S. Y. Chui, S. M. F. Lo, J. P. H. Charmant, A. G.
Orpen and I. D. Williams, Science, 1999, 283, 1148.
5 Representative examples: (a) K. C. Stylianou, J. Rabone, S. Y.
Chong, R. Heck, J. Armstrong, P. V. Wiper, K. E. Jelfs, S.
Zlatogorsky, J. Bacsa, A. G. McLennan, C. P. Ireland, Y. Z.
Khimyak, K. M. Thomas, D. Bradshaw and M. J. Rosseinsky,
J. Am. Chem. Soc., 2012, 134, 20466; (b) K. L. Mulfort and
J. T. Hupp, J. Am. Chem. Soc., 2007, 129, 9604; (c) B. Chen, C.
Liang, J. Yang, D. S. Contreras, Y. L. Clancy, E. B. Lobkovsky,
O. M. Yaghi and S. Dai, Angew. Chem., Int. Ed., 2006, 45,
1390; (d) M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J.
Wachter, M. O'Keeffe and O. M. Yaghi, Science, 2002, 295,
469.
6 (a) R. Sen, D. Saha, S. Koner, P. Brandao and Z. Lin, Chem. –
Eur. J., 2015, 21, 5962; (b) D. L. Reger, D. M. Smith, G. J.
Long and F. Grandjean, Inorg. Chem., 2011, 50, 686; (c) D. L.
Reger and M. D. Smith, Inorg. Chem., 2011, 50, 11754; (d) A.
Aijaz, P. Lama and P. K. Bharadwaj, Inorg. Chem., 2010, 49,
5583; (e) C.-C. Wang, C.-T. Yeh, K.-Yi. Cheng, P.-C. Chand,
M.-L. Hp, G.-H. Lee, H.-S. Shih and H.-S. Sheu, Inorg. Chem.,
2011, 50, 597; ( f ) A. Michaelides and S. Skoulika, Cryst.
Growth Des., 2005, 5, 529.
Synthesis of {[ZnIJbpaipa)]·DMF·2H2O}n (1)
A mixture of ZnIJOAc)2·2H2O (22 mg, 0.1 mmol) and H2bpaipa
(36.3 mg, 0.1 mmol) in DMF/H2O (1 mL/1 mL) was heated in
a 5 mL capacity Teflon-lined stainless-steel reactor at 120 °C
for 48 h and then cooled to room temperature in 24 h. Color-
less block-shaped crystals were collected via filtration and
washed with a 1 : 1 mixture of acetonitrile and toluene to
remove the acetic acid by-product followed by drying in air.
7 (a) H. Li, M. Eddaoudi, M. O'Keeffe and O. M. Yaghi, Nature,
1999, 402, 276; (b) C. J. Kepert and M. J. Rosseinsky, Chem.
Commun., 1999, 375; (c) D. Bradshaw, J. E. Warren and M. J.
This journal is © The Royal Society of Chemistry 2015
CrystEngComm

View Article Online
Communication
Rosseinsky, Science, 2007, 315, 977; (d) M. P. Suh, J. W. Ko
CrystEngComm
426.72, T = 100 K, monoclinic P21/n, a = 8.485(5) Å, b =
14.529(9) Å, c = 14.073(8) Å, α = 90°, β = 94.11IJ3)°, γ = 90°, V
and H. J. Choi, J. Am. Chem. Soc., 2002, 124, 10976.
8 (a) T. K. Maji, K. Uemura, H.-C. Chang, R. Matsuda and S.
Kitagawa, Angew. Chem., Int. Ed., 2004, 43, 3269; (b) C.-D.
Wu and W.-B. Lin, Angew. Chem., Int. Ed., 2005, 44, 1958.
9 (a) S. Khullar and S. K. Mandal, Cryst. Growth Des., 2012, 12,
5329; (b) S. Khullar and S. K. Mandal, Cryst. Growth Des.,
2013, 13, 3116; (c) S. Khullar and S. K. Mandal,
CrystEngComm, 2013, 15, 6652; (d) S. Khullar, V. Gupta and
S. K. Mandal, CrystEngComm, 2014, 16, 5705; (e) S. Khullar
and S. K. Mandal, Cryst. Growth Des., 2014, 14, 6433; ( f ) S.
Khullar and S. K. Mandal, RSC Adv., 2014, 4, 39204.
10 (a) G. B. Deacon and R. J. Phillips, Coord. Chem. Rev.,
1980, 33, 227; (b) K. Nakamoto, Infrared and Raman Spectra
of Inorganic and Coordination Compounds, 5th Edn, John
Wiley and Sons, New York, 1997.
11 Crystal data for 1 and 2 that were collected with the use of a
Bruker Kappa APEX II diffractometer equipped with a CCD
detector and sealed-tube monochromated MoKα radiation (λ
= 1730.4(17) Å3, Z = 4, Dc = 1.638 g cm−3, μ = 1.454 mm−1
,
Rint = 0.138, final R1 = 0.0817, wR2 = 0.1894 for 1399 unique
reflections (I > 2σ). Full details are summarized in Table S1.†
12 APEX2, SADABS and SAINT, Bruker AXS inc: Madison, WI,
USA, 2008.
13 G. M. Sheldrick, Acta Crystallogr., Sect. A: Found. Crystallogr.,
2008, 64, 112.
14 C. F. Macrae, I. J. Bruno, J. A. Chisholm, P. R. Edginton, P.
McCabe, E. Pidocck, L. Rodriguez-Monge, T. Taylor, J. Van
de Streek and P. A. Wood, J. Appl. Crystallogr., 2008, 41, 466.
15 A. Addison, T. Rao, J. Reedijk, J. van Rijn and G. Verschoor,
J. Chem. Soc., Dalton Trans., 1984, 1349.
16 (a) H.-W. Kuai, X.-C. Cheng, L.-D. Feng and X.-H. Zhu, Z.
Anorg. Allg. Chem., 2011, 11, 1560; (b) X.-C. Cheng, X. Hong
and H.-W. Kuai, Z. Anorg. Allg. Chem., 2013, 68, 1007; (c) X.
Liu, M. Oh and M. S. Lah, Cryst. Growth Des., 2011, 11,
5064.
= 0.071073 Å) are as follows. For 1: C23H26N4O7Zn, Mr
=
17 A. L. Spek, PLATON, Version 1.62, University of Utrecht, 1999.
18 V. A. Blatov, A. P. Shevchenko and V. N. Serezhkin, J. Appl.
Crystallogr., 2000, 33, 1193, TOPOS software is available for
download at http://www.topos.ssu.samara.ru.
19 M. C. Das and P. K. Bharadwaj, J. Am. Chem. Soc., 2009, 131,
10942.
535.85, T = 100 K, monoclinic P21/n, a = 8.7542(8) Å, b =
16.4242IJ15) Å, c = 15.9879IJ15) Å, α = 90°, β = 91.709IJ2)°, γ =
90°, V = 2297.7(4) Å3, Z = 4, Dc = 1.549 g cm−3, μ = 1.122
mm−1, Rint = 0.0467, final R1 = 0.0443, wR2 = 0.1123 for 3076
unique reflections (I > 2σ). For 2: C20H15N3O4Zn, Mr
=
CrystEngComm
This journal is © The Royal Society of Chemistry 2015