Ligand and solvent effects in the formation and self-assembly of a metallosupramolecular cage

Article abstract of DOI:10.1039/C6NJ03456J

Two bis-pyridyl-bis-urea ligands namely N,N′-bis-(3-pyridyl)diphenylmethylene-bis-urea (L1) and N,N′-bis-(3-picolyl)diphenylmethylene-bis-urea (L2) have been reacted with a Cu(ii) salt resulting in the formation of a metallosupramolecular cage [{Cu_2<

Full text of DOI:10.1039/C6NJ03456J

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ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
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Ligand and solvent effects in the formation and self-assembly of a
metallosupramolecular cage
N. N. Adarsh,a,b* Amarnath Chakrabortya,c* Màrius Tarrés,d Surjendu Dey,a,e Fernando Novio,b
Basab Chattopadhyay,f Xavi Ribas,d Daniel Ruiz-Molinab,*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Two bis-pyridyl-bis-urea ligands namely N,N’-bis-(3-pyridyl)diphenylmethylene-bis-urea (L1) and N,N’-bis-(3-
www.rsc.org/
picolyl)diphenylmethylene-bis-urea (L2) have been reacted with
a Cu(II) salt resulting in the formation of the
metallosupramolecular cage [{Cu2(μ-L1)4(DMSO)2(H2O)2}·SO4·X] (1) and the one dimensional coordination polymer
[{Cu(1)(μ-L2)2(H2O)2}{Cu(2)(μ-L2)2(H2O)2}·2SO4·9H2O.X]n (2) (where DMSO = Dimethysulfoxide, X = disorder lattice included
solvent molecules), respectively. The single crystal structures of 1 and 2 are discussed in the context of the effect of the
ligands, hydrogen bonding functionality of ligand on the supramolecular structural diversities observed in these metal
organic compunds. The supramolecular packing of the 1 is clearly influenced by the nature of the solvent and ligand used;
mixtures of DMSO/MeOH or DMSO/H2O lead to the obtaining of blue crystals or
a hydrogel, respectively.
Coordination geometry of the metal center (octahedral or
square planar) and the nature of the counter anions are
relevant factors to control the formation of M2L4 cages.8
Though, it often results difficult to predict the final outcome of
a properly pre-designed reaction to form M2L4 cages taking
into account exclusively the aforementioned parameters; for
this reason other factors must be considered.9 Among them,
systematic studies that allow for a proper and judicious ligand
and solvent selection represents one of the most challenging
matters.
Introduction
Metallosupramolecular cages (MSC) are formed by the
coordination driven supramolecular self-assembly of metal
ions and organic ligands, which depending on the
stoichiometric ratio can lead to different architectures.1
Among these, the family of MSCs termed as M2L4 (where M =
metal ion and L = organic ligand) has attracted the attention of
many researchers due to its simple and low symmetry
structurally related to that of cryptands.2 Moreover, the
nanoscopic cavities inside the cages of these materials have
already been successfully used for several potential
Herein we report a systematic study of two bis-urea-bis-pyridyl
ligands, namely N,N’-bis-(3-pyridyl)diphenylmethylene-bis-
urea (L1) and N,N’-bis-(3-picolyl)diphenylmethylene-bis-urea
(
L2), the last having two additional carbon atoms and different
applications
ranging
from
the
encapsulation
of
environmentally relevant anions3 or cancer drugs such as cis-
platin,4 to induce catalytic reactions,5 luminescence,6
separation techniques or the intracellular release of
photosensitizers.7
conformational isomers (see Scheme 1 and ESI, S1). We will
demonstrate how such minor modification strongly modifies
the outcome of the reaction. While ligand L1 leads to the
formation
of
a
binuclear
complex
[{Cu2(μ-
L1)4(DMSO)2(H2O)2}·SO4·X] (
1) with a M2L4 cage structure,
model ligand L2 used for comparison purposes, yields a
polymeric structure with general formulae [{Cu(1)(μ-
L2)2(H2O)2}{Cu(2)(μ-L2)2(H2O)2}·2SO4·9H2O·X]n
(2). Moreover,
the supramolecular organization of 1 is tuned, thanks to the
capability of ligand L1 to form hydrogen bonds through the
urea groups,10,11 representing such control an issue of
increasing relevance in crystal engineering.9 For instance, use
of DMSO/MeOH as solvent reaction leads to the formation of
blue single crystals while the use of DMSO/H2O results in the
formation of a hydrogel G1
.
Results and discussion
Ligand effect
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A methanolic solution of CuSO4·5H2O was layered over a The dark blue colored octahedral crystals of
1
crystallize in a
DMSO solution of L1 (details in experimental section) and kept centrosymmetric tetragonal space group I4/m (Table 1). The
at ambient condition for approximately one week. The asymmetric unit contains one fourth of a metal center Cu(II),
resulting crystalline material was subjected to various one fourth of a molecule of water (disorder over two
physicochemical studies including single-crystal X-ray positions), one fourth of a molecule of dimethyl sulfoxide
diffraction
(SXRD)
and
characterized
as
[{Cu2(μ- (DMSO) (both DMSO and water were coordinated to Cu(II)),
one fourth of a non-coordinated sulfate anion (all are located
on a four fold axis), a half molecule L1 (the central carbon
atom of the ligand L1 was positioned at the 2-fold symmetry
axis and as a result, therefore only half of the ligand was
located in the asymmetric unit) and some unaccounted
electron densities (1031 e/Å3 per unit cell) presumably coming
from disordered solvent molecules. The Cu(II) metal center
L1)4(DMSO)2(H2O)2}·SO4·X] (
1
).
displays a slightly distorted octahedral geometry [∠N–Cu–N =
89.831(10)°; N–Cu–O = 93.10(9)°]; the equatorial positions
∠
are occupied by the pyridyl N atoms of the L1 and the apical
positions are coordinated by the DMSO and water molecule
(water molecule is very weakly coordinated to the metal
center because of the disorder of water molecules over two
positions).
Scheme 1. Chemical structure of ligands L1 and L2
b)
a)
c)
Cu
N
C
H
O
S
d)
2-
Figure 1. Crystal structure illustration of 1 – a) metallosupramolecular cage (orange sphere represent the void space within the cage); b) interaction of SO4 (orange-red color
space-fill model) with urea moiety of four units of metallosupramolecular cage; c) and d) overall packing of 1 along the crystallographic axis “c” and “b”, respectively.
2 | J. Name., 2012, 00, 1-3
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The ligand L1 exhibits energetically more favorable syn-syn Alternatively, a methanolic solution of CuSO4·5H2O was also
conformation around the central methylene carbon atom and layered over a DMSO solution now of L2. After one week, a
keeping the urea >C=O groups syn to each other. The terminal pale blue colored crystalline material was obtained. The
pyridyl moieties which were coordinated to the Cu(II) metal resulting crystalline material was subjected to various
center were oriented in syn-syn fashion (relative to the physicochemical studies (see Experimental Section) including
adjacent urea >C=O) resulting in an angular ligating topology. single-crystal X-ray diffraction (SXRD) and characterized as
The conformational (syn-syn-syn – Figure S1) dependent [{Cu(1)(μ-L2)2(H2O)2}{Cu(2)(μ-L2)2(H2O)2}·2SO4·9H2O.X]n
(2).
angular ligating topology of the ligand L1, metal : ligand ratio The pale blue colored thin plate shaped crystals did not diffract
(1 : 2), and coordination mode of counter anion sulfate leads beyond a 2θ of 27º (even after repeated data collections),
to the formation of a dinuclear Cu(II) MSC. Interestingly, the reason why the structure was not anisotropically refined. The
MSC has an oval shaped cage [12.54 X 4.3Å by taking van der crystals belong to centrosymmetric triclinic space group P-1
Waals radii into account] wherein all the urea N–H moieties (Table 1). The asymmetric unit contains two Cu(II) centers
are pointed outwards and because of this reason the sulfate [Cu(1) and Cu(2)], two pairs of ligand L2, two pairs of water
anion recognition inside the cage space is not taking place. molecules (each pairs of ligands and water molecules were
Instead, the cage space was filled with metal bound DMSO coordinated to metal centers Cu(1) and Cu(2) and form two
molecules and other disordered lattice included solvent different crystallographically independent units and some
molecules. The sulfate counter anion is involved in hydrogen unaccounted electron densities (164 e/Å3 per unit cell)
bonding with the urea functionality of L1 [N…O = 2.893(5)– presumably coming from disordered solvents.
2.954(5)Å;
∠N–H…O = 157.2–160.6°] and each sulfate anion is The Cu(II) metal center displays a slightly distorted octahedral
involved in such hydrogen bonding with other four different geometry; the equatorial positions are occupied by the pyridyl
MSCs leads to the formation of a three dimensional hydrogen N atoms of the L2 and the apical positions are coordinated by
bonded network structure (Figure 1, Table S1 - ESI†). Overall water molecule.
packing of the MSCs revealed the presence of channels
running along crystallographic axis “b” (Figure 1d). The
Crystal data
1
913699
C122H186Cu2N24O43S13
3220.81
0.32 x 0.24 x 0.18
Tetragonal
I4/m
17.3071(6)
17.3071(6)
28.5287(12)
2
913700
C108H146Cu2N24O37S2
2563.69
0.06 x 0.02 x 0.01
Triclinic
Pꢀ1
presence of unaccounted electron density peaks were CCDC Number
Empirical formula
observed within such channels during the final cycles of
Formula weight
Crystal size (mm)
Crystal system
Space group
a (Å)
refinement, which could not be model to any reasonable
solvent molecule. Thus SQUEEZE12 calculations were carried
out, which revealed that there were 515.5 electrons per
asymmetric unit, which were attributed to solvents used for
crystallization (8 DMSO, 7 MeOH and 5.35 molecules of H2O).
14.456(5)
20.541(7)
22.843(9)
73.881(9)
79.477(10)
88.620(9)
6404(4)
b (Å)
c (Å)
α (°)
β (°)
γ (°)
Thermogravimetric (TG) data of
1
indicated a weight loss of
C which could
30.9 % within the temperature range of 26-159
°
be attributed to the loss of lattice included and metal bound
solvent molecules [calcd. weight loss for 5.35 H2O (disordered)
+ 2 H2O (metal bound) + 8 DMSO (disordered) + 2 DMSO
(metal bound) + 7 MeOH = 35.4%)]. The difference in the
calculated and experimental result may be due to the fast
Volume (Å3)
8545.4(6)
2
1.252
3392
0.484
100(2)
Z
2
Dcalc.(g/cm3)
1.330
2696
0.451
100(2)
F(000)
ꢀ MoKα (mm–1)
Temperature (K)
escape of disordered lattice included MeOH molecules (weight Range of h, k, l
θ min/max
–18/19, –19/20, –32/32 –9/9, –13/13, –15/15
1.38/24.26
0.94/13.69
loss of 4.5 MeOH = 4.5%) before loading the sample for TG
Reflections
collected/unique/observed
experiment (Figure S3, ESI†). Thus the TG data corroborated
37895/3562/3154
3562/0/190
0.970
14199/3971/2892
3971/0/661
1.090
well with the SQUEEZE calculations (Figure S3 of the ESI).
Data/restraints/parameters
Goodness of fit on F2
Final R indices [I>2σ(I)]
R1 = 0.0677
wR2 = 0.1993
R1 = 0.0787
wR2 = 0.2113
R1 = 0.0964
wR2 = 0.2381
R1 = 0.1235
wR2 = 0.2596
R indices (all data)
Table 1: Crystal data for complexes 1 and 2
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a)
b)
c)
2-
Figure 2. Crystal structure illustration of 2 – a) 1D looped chain CP; b) two-dimensional hydrogen bonded sheet as a result of SO4 bridging of the 1D coordination polymeric
2-
looped chains (color code: Cu – magenta with space-fill model, O – red, 1D CP loops – orange and grey, SO4 – red-orange with space-fill model); c) overall packing of two
dimensional sheets (alternate sheets are shown in grey-orange with space-fill model and purple-green with ball and stick model) via various hydrogen
The ligand L2 exhibits energetically less favorable syn-syn resulted in the formation of a gel (G1) stable under ambient
conformation around the central methylene carbon atom and conditions for more than a week,13 with a minimum gelator
keeping the urea >C=O groups syn to each other (see ESI, concentration (MGC) of 5.1 wt %. Moreover, G1 did not show
Figure S2).
any thermo-reversible behavior indicating the coordination
polymeric nature of the gel network.
Solvent effect
As a representative example, the photographs of the hydrogel
As previously described, when the formation of complex
1
and single crystals obtained from reaction of CuSO4 with L1
takes place in a DMSO/MeOH mixture, blue color block shaped under the two different conditions are shown in Figure 3.
single crystals are obtained. For comparison purposes, the Morphological characterization by FE-SEM revealed the
reaction was repeated using now a DMSO/H2O mixture. presence of a rough material with voids and wrinkles arising
Replacement of MeOH by H2O from the DMSO mixture from agglomeration (Figure 4). Rheological response of G1
4 | J. Name., 2012, 00, 1-3
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using dynamic rheology was tested, displaying a typical gel-like morphologies: I) flakes, for samples obtained upon re-
rheological response. Note that G´ is independent of frequency dispersion in H2O and related mixtures (CH3CN-H2O or MeOH-
and considerably higher than G´´ over the range of frequencies H2O) and II) mixtures of nanoparticles and flakes for organic
(see ESI, Figure S6). Worth to mention, Steed and coworkers solvents such as CH3CN and CH3OH. Energy dispersive X-ray
reported the tuning nature of rheological property of Cu(II) (EDX) revealed the presence of copper metal ions for both
and AgI gels derived from L1 based on the crystal structure of flakes and nanoparticles, exhibiting in both cases a good match
the gelator.14 In fact it is proved from the single crystal X-ray (see ESI, Figure S4). PXRD revealed that samples containing
structure analysis study that the interaction of metal ions exclusively flake material exhibit the same crystalline pattern
(Cu(II) and AgI) with pyridyl urea ligands induce gelation that the as-synthesized G1 sample.
through metal cross-linked urea tape motif, or a metal cross-
linked combination of urea tape and urea anion/urea solvent
interactions.14b The crystal structures that we reported here
also showed a directional hydrogen bonding interactions
through urea…sulfate anion. Finally, indexing of the powder
diffraction pattern of G1 using the program DICVOL0615
showed a orthorhombic unit cell with a = 29.71 (3), b =
18.89(2), c = 15.73(1)Å; Vol = 8825.63Å3, related though
different to the tetragonal (ESI, Figure S5).
Figure 3. Photographs of the single crystals 1 (a) and gel G1 with the characteristic
tube inversion (b). FE-SEM micrograph of the xerogel of G1 (c)
Solvent-tuned morphology
Finally, since the effect of solvent on the morphology of G1
was studied at room temperature and under air conditions
using a 1 mol% colloidal suspension of G1 treated with
different solvents. For this, first aliquots of G1 were first
dispersed in different solvent mixtures (H2O, CH3CN-H2O,
MeOH-H2O, CH3CN and CH3OH) and analyzed by SEM, TEM,
and PXRD. Some of the results are shown in Figure 4. SEM
images reveal that all the materials can be grouped into two
Figure 4. SEM pictures of the xerogel catalyst G1 obtained after reaction in various
solvents - a) H2O, b) H2O-MeOH, c) H2O-CH3CN, d) CH3CN, e) MeOH, f) TEM image of
xerogel catalyst G1 obtained from MeOH displaying the nanoparticles; g) PXRD patterns
of G1 under various conditions – color codes: red – as synthesized; orange and blue –
obtained from MeOH and CH3CN respectively; green, magenta and brown - obtained
from H2O, H2O-MeOH and H2O-CH3CN respectively.
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In the case of sample re-dispersion in CH3CN and CH3OH, 262ºC. Anal. Calcd for C25H25N6O2 (%): C, 68.48; H, 5.06; N,
1
additional Bragg peaks are observed most likely arising from 19.17. Found: C, 64.40; H, 5.22; N, 18.67. H NMR (300 MHz,
the nanoparticles though this fact cannot be fully confirmed DMSO-d6): δ = 8.76 (2H, s, urea N-H), 8.69 (2H, s, urea N-H),
since, in spite several different solvent mixtures were assayed, 8.57 (2H, s, Py-H), 8.16-8.15 (2H, d, J = 3.0 Hz, Py-H), 7.92-7.90
in none of the cases a sample containing the material (2H, d, J = 6.0 Hz, Py-H), 7.36-7.32 (2H, d, J = 12.0 Hz, Ar-H),
nanostructured as pure nanoparticles was obtained. FT-IR 7.29-7.26 (2H, dd, J = 3.0, 6.0 Hz, Py-H), 7.12-7.08 (2H, d, J =
confirm the chemical integrity of the cage
solvents (Figure S7, ESI).
1
the different 12.0 Hz, Ar-H), 3.80 (2H, s, -CH2-) ppm. 13C NMR (300 MHz,
DMSO-d6): 153.2 (C), 143.4 (CH), 140.6 (CH), 137.9 (C), 137.0
(C), 136.0 (C), 129.5 (CH), 125.7 (CH), 124.2 (CH), 119.3 (CH),
40.6 (CH2) ppm. FT-IR (KBr pellet): 3302 (s, urea ν N-H), 3178w,
3036 (m, aromatic ν C-H), 2937w, 1691w, 1651 (s, urea ν C=O),
1599 (s, urea δ N-H), 1558s, 1531s, 1512s, 1481m, 1419s,
1408m, 1300m, 1286m, 1253m, 1234w, 1219w, 1188w,
Conclusions
In summary, we have demonstrated the supramolecular
structural diversities as a function of the conformation of two
1118w, 1022w, 902w, 864w, 773m, 702m, 632w, 619w cm-1.
MS calcd for C15H18N6O2 [M+H]+: 439.18; found: 439.13.
analogous bis-urea-bis-pyridyl ligands L1 and L2
. Minor
L2 (N,N’-bis-(3-picolyl)diphenylmethylene-bis-urea): To
a
differences in the nature of the ligands have been shown to
strongly influence the final outcome of the reaction. While
stirring solution of diphenylmethane-4,4'-isocyanate (2 g, 7.9
mmol) in dry dichloromethane solution, a solution of 3-
picolylamine (1.7 g, 15.8 mmol) in dry dichloromethane was
added dropwise. The white colored turbid solution became a
thick white precipitate, which was further stirred at room
temperature for 24 h. After filtration, the precipitate was
washed with dichloromethane and air dried. The crude
product thus obtained was then dissolved in DMF, and further
addition of distilled water gave L2 as a gelly precipitate, which
was then filtered and air dried (800 mg, 70% yield). mp 196ºC.
Anal. Calcd for C27H26N6O2·2H2O (%): C, 64.53; H, 6.02; N,
ligand L1 yields to the formation of the metallocage 1, ligand
L2 leads to the formation of a 1-D coordination polymer.
Moreover, the ability of ligand L1 to form supramolecular
bonds through π-π interactions, but mainly hydrogen bonds,
has been afterwards used to obtain polymorphs with different
morphologies, from single crystals to a gel or microcrystalline
powder made of flakes and/or nanoparticles.
Experimental
1
16.72. Found: C, 64.82; H, 5.92; N, 16.42. H NMR (300 MHz,
Materials and method
DMSO-d6): δ = 8.49 (2H, s, urea N-H), 8.48 (2H, s, Py-H), 8.42
(2H, s, urea N-H), 7.68-7.66 (2H, d, J = 6.0 Hz, Py-H), 7.34-7.30
(2H, dd, J = 3.0, 6.0 Hz, Py-H), 7.28-7.26 (2H, d, J = 6.0 Hz, Ar-
H), 7.03-7.01 (2H, d, J = 6.0 Hz, Ar-H), 6.61-6.59 (2H, d, J = 6.0
Hz, Py-H), 4.29-4.28 (4H, d, J = 3.0 Hz, -CH2-), 3.73 (4H, s, -CH2-)
ppm. 13C NMR (300 MHz, DMSO-d6): 155.9 (C), 149.3 (CH),
148.6 (CH), 138.8 (C), 136.5 (C), 135.5 (C), 135.1 (CH), 129.4
(CH), 124.0 (CH), 118.6 (CH), 41.1 (CH2), 40.6 (CH2) ppm. FT-IR
(KBr pellet): 3304 (s, urea ν N-H), 3032 (m, aromatic ν C-H),
2875w, 1635 (s, urea ν C=O), 1593 (s, urea δ N-H), 1566s,
1510s, 1481s, 1465s, 1427s, 1408s, 1301s, 1240s, 1230s,
1190m, 1178w, 1105m, 1057m, 1028m, 810m, 773m, 756m,
711s, 661m, 524w cm-1. MS calcd for C15H18N6O2 [M+H]+:
467.22; found: 467.14.
All chemicals were commercially available (Aldrich) and used
without further purification. The ligand N,N’-bis-(3-
pyridyl)diphenylmethylene-bis-urea L1 was previously
reported by Steed et al.14 and the ligand N,N’-bis-(3-
picolyl)diphenylmethylene-bis-urea L2 was prepared by mixing
3-picoly amine and diphenylmethane-4,4'-isocyanate. The
elemental analysis was carried out using a Perkin-Elmer 2400
Series-II CHN analyzer. FT-IR spectra were recorded using
Perkin-Elmer Spectrum GX and TGA analyses were performed
on a SDT Q Series 600 Universal VA.2E TA instrument. X-ray
Powder Diffraction (PXRD) patterns were recorded on a Bruker
AXS D8 Advance Powder (Cu Kα1 radiation, λ = 1.5406 Å) X-ray
diffractometer. Scanning electron microscopy (SEM) was
recorded in a JEOL, JMS-6700F, Field Emission Scanning
Electron Microscope. Rheology experiments were performed
in SDT Q Series Advanced Rheometer AR 2000.
1
: An aqueous methanolic solution of CuSO4·5H2O (11.4 mg,
0.0455 mmol) was layered over a DMSO solution of L1 (40 mg,
0.091 mmol). After four days, dark blue colored octahedral
shaped crystals of metalla-macro-tricylic cryptand
1 was
Synthesis
obtained. Yield: 23 mg (41%) Anal. data calc. for
C102H104N24O22Cu2S2.8H2O.2DMSO: C, 50.73; H, 5.30; N, 13.39;
S, 5.11 Found: C, 50.74; H, 5.22; N, 13.20; S, 5.01 FT-I.R (KBr,
cm-1): 3276 (sb, urea ν N-H), 3064 (sb, aromatic ν C-H), 1703s,
1664 (s, urea ν C=O), 1604, 1591 (s, urea δ N-H), 1514s, 1523s,
1485s, 1427s, 1298s, 1242s, 1207s, 1116 (s, sulfate ν S=O),
1064s, 1020s, 952w, 912w, 806m, 700m, 649w, 611w, 501w
cm-1.
L1 (N,N’-bis-(3-pyridyl)diphenylmethylene-bis-urea): To
a
stirring solution of diphenylmethane-4,4'-isocyanate (2 g, 7.9
mmol) in dry dichloromethane solution, a solution of 3-
aminopyridine (1.48 g, 15.8 mmol) in dry dichloromethane was
added dropwise. The white colored turbid solution became a
thick white precipitate, which was further stirred at room
temperature for 24 h. After filtration, the precipitate was
washed with dichloromethane and air dried. The crude
product thus obtained was then dissolved in DMF, and further
addition of distilled water gave L1 as a precipitate, which was
then filtered and air dried (3.2g, 70% yield). Decomposed at
2
: An aqueous methanolic solution of CuSO4·5H2O (13.4 mg,
0.0535 mmol) was layered over a DMSO solution of L2 (50 mg,
0.107 mmol). After one week, pale blue colored plate shaped
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crystals of
ARTICLE
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were obtained. 2: Anal. data calc. for
C54H60N12O16Cu2S2.8H2O: C, 44.17; H, 5.22; N, 11.45 Found: C,
44.47; H, 5.02; N, 11.84. FT-I.R (KBr, cm-1): 3410 (sb, water ν O-
H), 3315 (sb, urea ν N-H), 3086 (sb, aromatic ν C-H), 2910m,
1691 (s, urea ν C=O), 1618 (s, urea δ N-H), 1560s, 1489s,
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1095s 1051s, 802m, 698m cm-1.
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1 was collected using Mo Kα (λ =
0.7107 Å) radiation on a SMART APEX II diffractometer
equipped with CCD area detector. Data collection, data
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using the software package of SMART APEX II. Synchrotron
4
5
J. E. M. Lewis, E. L. Gavey, S. A. Cameron and J. D. Crowley,
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keV at the Australian Synchrotron, Australia. All structures
were solved by direct method and refined in a routine manner.
In most of the cases, non-hydrogen atoms were treated
anisotropically. In most of the cases, hydrogen atom positions
were generated by their idealized geometry and refined using
a riding model; whenever possible, the hydrogen atoms
associated with the lattice included solvents or metal-
coordinated solvents were located and refined. Graphics were
generated with MERCURY 2.3 and Diamond Version 3. CCDC
5
6
7
8
9
codes of 1 and 2 are 913699 and 913700, respectively.
Acknowledgements
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3039-3060
,
We thank Department of Science & Technology (DST), New
Delhi, India for financial support. This work was also supported
by project MAT2012-38318-C03-02 (to DR) and CTQ-2013-
43012-P (to XR) from the Spanish Government and by FEDER
funds. ICN2 acknowledges support from the Severo Ochoa
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support and help with the initial results. B.C. kindly
acknowledges financial support from the FRS-FNRS (Belgian
National Scientific Research Fund) for the POLYGRAD Project
22333186. B.C is a FRS-FNRS Research Fellow. Single crystal X-
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1 was performed at the DST-funded National
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†
1
Electronic Supplementary Information (ESI) available:
Hydrogen bonding parameters of Conformational
possibilities for ligands L1 and L2, TGA of crystals of
Rheology, SEM, TEM and EDX of xerogel G1 FT-IR
comparison plot and crystallographic data in CIF format. See
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,
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A metallosupramolecular cage and a one dimensional coordination polymer have been
synthesized and structurally characterized by single crystal X-ray diffraction.