Combined solution-phase, solid-phase and phase-interface anion binding and extraction studies by a simple tripodal thiourea receptor

Article abstract of DOI:10.1002/ejic.201200776

Tris(2-aminoethyl)amine (tren) based 4-cyanophenyl-substituted tripodal L, tris{[(4-cyanophenyl)amino]ethyl}thiourea receptor, was synthesized and explored thoroughly for anion recognition in solution by NMR spectroscopy and isothermal titration calorimetry (ITC) as well as in the solid state by single-crystal X-ray diffraction studies. Anion recognition properties of L were further exploited toward the extraction of sulfate as well as fluoride from aqueous media using a liquid-liquid extraction technique. A solution-state anion binding study using NMR spectroscopy in [D₆]DMSO and ITC measurements in dry acetonitrile show a relatively higher association constant of L with halides (F^- and Cl^-) over oxyanions (H₂PO ₄^- and HSO₄^-). The single-crystal X-ray structural analysis of complex 1 reveals a monotopic encapsulation of fluoride in L through six N-H...F^- interactions with a distorted trigonal-prismatic geometry, whereas sulfate and carbonate induce dimeric assemblies of L in complexes 2 and 3, respectively. In the case of sulfate, a tight dimeric capsular assembly of ca. 9.5 A is observed through 15 N-H...O interactions, whereas carbonate forms a sandwich-like dimeric molecular aggregation through 14 N-H...O interactions. In the presence of tetrabutylammonium iodide as the phase transfer agent, L has shown ca. 70 % extraction of fluoride (based on L) and ca. 40 % extraction of sulfate (based on L) from aqueous solutions using an anion-exchange-based liquid-liquid extraction strategy. Extraction of these anions is unambiguously demonstrated by ¹H NMR, ¹⁹F NMR and FTIR spectroscopy, PXRD and single-crystal X-ray diffraction studies. A simple tripodal thiourea receptor can extract fluoride as well as sulfate from aqueous media by a liquid-liquid extraction technique using an anion-exchange strategy. Copyright

Full text of DOI:10.1002/ejic.201200776

FULL PAPER
DOI: 10.1002/ejic.201200776
Combined Solution-Phase, Solid-Phase and Phase-Interface Anion Binding and
Extraction Studies by a Simple Tripodal Thiourea Receptor
Purnandhu Bose,[a] Ranjan Dutta,[a] Saikat Santra,[a] Bijit Chowdhury,[a] and
Pradyut Ghosh*[a]
Keywords: Host-guest systems / Liquid-liquid extraction / ITC studies / NMR titrations / X-ray diffraction / Receptors
Tris(2-aminoethyl)amine (tren) based 4-cyanophenyl-substi-
tuted tripodal L, tris{[(4-cyanophenyl)amino]ethyl}thiourea
receptor, was synthesized and explored thoroughly for anion
recognition in solution by NMR spectroscopy and isothermal
titration calorimetry (ITC) as well as in the solid state by sin-
gle-crystal X-ray diffraction studies. Anion recognition prop-
erties of L were further exploited toward the extraction of
sulfate as well as fluoride from aqueous media using a li-
sulation of fluoride in L through six N–H···F– interactions with
a distorted trigonal-prismatic geometry, whereas sulfate and
carbonate induce dimeric assemblies of L in complexes 2 and
3, respectively. In the case of sulfate, a tight dimeric capsular
assembly of ca. 9.5 Å is observed through 15 N–H···O interac-
tions, whereas carbonate forms a sandwich-like dimeric mo-
lecular aggregation through 14 N–H···O interactions. In the
presence of tetrabutylammonium iodide as the phase transfer
agent, L has shown ca. 70% extraction of fluoride (based on
L) and ca. 40% extraction of sulfate (based on L) from aque-
ous solutions using an anion-exchange-based liquid–liquid
extraction strategy. Extraction of these anions is unambigu-
ously demonstrated by 1H NMR, 19F NMR and FTIR spec-
quid–liquid extraction technique.
A solution-state anion
binding study using NMR spectroscopy in [D6]DMSO and
ITC measurements in dry acetonitrile show a relatively
higher association constant of L with halides (F– and Cl–) over
–
oxyanions (H2PO4 and HSO4–). The single-crystal X-ray
structural analysis of complex 1 reveals a monotopic encap- troscopy, PXRD and single-crystal X-ray diffraction studies.
and synergized ion-exchange strategies for sulfate extrac-
Introduction
tion.[7c,7d] A neutral hexakis(urea) receptor for the extrac-
Extraction of anions like fluoride and sulfate from aque-
tion of sulfate from an aqueous environment using tetrabu-
ous media is one of the prime challenges in supramolecular
tylammonium chloride as a phase-transfer agent has been
chemistry owing to their high hydration energies (ΔGh
=
demonstrated by Wu et al.[8] Very recently, our group has
shown efficient and quantitative extraction of sulfate em-
ploying liquid–liquid extraction techniques utilizing a car-
bonate capsule of a tripodal tris(urea) receptor as an ex-
tractant.[9] Recent literature of anion coordination chemis-
try reveals the potential of tren-based tripodal urea and
thiourea receptors toward recognition, sensing, extraction
and transportation of various anions like fluoride, chloride,
sulfate and phosphate etc.[10–16] Morán et al. first employed
the tren-platform-based urea receptor for solution-state
phosphate binding studies.[11] The anion recognition
pattern, selectivity etc. can be influenced by varying the at-
tached moiety to the tren (N4) unit, because the electron-
withdrawing property of various functional groups can
modify the hydrogen-bonding ability differently. Custelcean
and co-workers have extensively used pyridyl-functionalized
urea-based metal–organic frameworks for selective separa-
tion of sulfate from aqueous media.[12] Our group has ex-
plored the pentafluorophenyl-substituted fluorinated tripo-
dal urea receptor for anion recognition, fixation of aerial
carbon dioxide as a carbonate capsule and extraction of
sulfate from water.[13] Very recently, Gale et al. have illus-
trated the involvement of a series of fluorinated urea/thio-
–465 kJmol–1 for fluoride and ΔGh = –1080 kJmol–1 for
sulfate).[1] Fluoride and sulfate are important targets in the
recognition as well as extraction studies because of their
pivotal role in environmental and biological aspects as well
as drinking-water purification processes.[2] Apart from some
chemodosimetric approaches for fluoride detection in
water,[3] extraction of fluoride from aqueous solution was
achieved recently by a charged phosphonium receptor by
Das et al.[4] Some heteroditopic receptors have also been
developed by Sessler et al. for the recognition and extrac-
tion of fluoride from an aqueous environment.[5] Our group
has recently demonstrated a dual-host approach for the li-
quid–liquid extraction of potassium fluoride from aqueous
media.[6] On the other hand, different approaches have been
employed for liquid–liquid extraction techniques of sulf-
ate.[7] Sessler and Moyer et al. have widely used dual-host
[a] Department of Inorganic Chemistry, Indian Association for the
Cultivation of Science,
2A & 2B Raja S. C. Mullick Road, Kolkata 700032, India
E-mail: icpg@iacs.res.in
Homepage: http://www.iacs.res.in/inorg/icpg/
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201200776.
Eur. J. Inorg. Chem. 2012, 5791–5801
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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P. Bose, R. Dutta, S. Santra, B. Chowdhury, P. Ghosh
FULL PAPER
urea-based tripodal anion receptors in transmembrane changes upon addition of different anions to the solution
anion transport as well as anticancer activity.[14] In cases of L are shown in Figure 1. In the case of F– the most
of (nitrophenyl)urea and thiourea receptors sulfate/water/ substantial change was observed for the thiourea protons,
–
–
sulfate assembly,[15a] dimeric assembly of sulfate[15c] and tri- whereas Cl–, Br–, HSO4 and H2PO4 showed appreciable
valent phosphate capsules,[15b] have also been achieved. Re- changes in the chemical shift of the thiourea NH protons.
cent reports by Hossain et al. on a tren-based tripodal (p- This indicates that the thiourea NH group of L provides
cyanophenyl)urea receptor LЈ have shown anion-binding the sites of interaction with these anions. In the case of I–
–
properties in solution.[16] Generally, ureas are less soluble and NO3 no such visible shift was noticed indicating an
in common organic solvents compared with corresponding energetically unfavourable interaction of these two anions
thioureas. To overcome the solubility problem of liquid– with L. Binding constants of five interacting anions (F–,
–
–
1
liquid extraction studies we have synthesized the tripodal Cl–, Br–, HSO4 , H2PO4 ) were determined by H NMR
(p-cyanophenyl)thiourea L and have established it as a neu- titration experiments of L with their tetrabutylammonium
tral anion receptor by extensive solution-phase, solid-state salts in [D6]DMSO at 298 K (Figure 2 and Figures S11–S14
structural studies. We have illustrated the monotopic encap- of the Supporting Information). Except for sulfate the ti-
sulation of fluoride (spherical) by the neutral receptor L, tration curve of all these investigated anions gives the best
sulfate (tetrahedral) assisted dimeric capsular assembly of fit for a 1:1 binding of host/guest, in agreement with Job’s
L and sandwich-type molecular aggregation of L upon car- plots indicating a maximum Δδ of around 0.5 = [L]/[L] +
bonate (planar) binding. Importantly, we have demon- [A]. The association constant was calculated using
strated L as a versatile receptor toward liquid–liquid extrac- EQNMR software. In the case of sulfate the Job’s plot
tion of fluoride and sulfate from aqueous media using tetra- analysis reveals a complex equilibrium with both 1:1 and
butylammonium iodide as an anion exchanger.
2:1 (host/guest) binding of sulfate to L (Figure S14, Sup-
porting Information). A representative titration profile of L
with Cl– is shown in Figure 2, and the stability-constant
results of all the anions are listed in Table 1. The binding-
constant values show that among all the investigated anions
L binds most strongly with the more basic F– with a logK
value of 3.57. However, Cl– also shows significant binding
to L (logK = 3.06), and weak binding is observed in the
Results and Discussion
The tripodal thiourea receptor L was synthesized in
quantitative yield by the reaction between tren and 3 equiv.
of 4-cyanophenyl isothiocyanate in dry dichloromethane as
the solvent (Scheme 1). Several attempts have been made to
obtain various anionic complexes of tetrabutylammonium
salts of L. We were able to isolate three complexes [L(F)]·
[nBu4N]·[CH3CN] (1), [2L(SO4)]·[nBu4N]2 (2) and
[2L(CO3)]·[nEt4N]2 (3) of L as crystals suitable for single-
crystal X-ray diffraction studies. All complexes were ob-
tained in good yield.
–
–
case of Br–. Surprisingly, oxyanions H2PO4 and HSO4
show relatively lower binding constants compared with F–
and Cl–. Thus, the receptor L follows the binding trend in
–
–
the order F– Ͼ Cl– Ͼ HSO4 Ͼ H2PO4 . The analogous
urea receptor LЈ follows the binding trend in the order F–
–
– [16]
Ͼ H2PO4 Ͼ Cl– ≈ HSO4 .
In general, urea/thiourea-
based tripodal receptors show a common trend of selectiv-
ity for oxyanions over halides.[13a,13b,14]
Scheme 1. Chemical structure of LЈ and L.
Solution-State Study
1H NMR Spectroscopic Studies
The solution-state binding properties of L with various
1
Figure 1. Partial H NMR spectra (300 MHz, [D6]DMSO, 298 K)
–
anions as their nBu4N+X– salts (X– = F–, Cl–, Br–, I–, NO3 ,
of L and downfield shift of thiourea NH proton signals upon ad-
–
–
HSO4 , H2PO4 ) were investigated by 1H NMR spectro-
dition of F–, Cl–, Br–, I–, HSO4 , H2PO4 and NO3 as their tetra-
–
–
–
scopic experiments in [D6]DMSO. The chemical shift butylammonium salts.
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Binding and Extraction Studies by a Simple Tripodal Thiourea Receptor
Figure 2. (a) Partial 1H NMR (300 MHz) spectral changes of L with added TBACl in [D6]DMSO (298 K) ([L]0 = 5.87 mm). Ratio of
concentration [Cl–]/[L]: (i) 0, (ii) 0.26, (iii) 0.39, (iv) 0.52, (v) 0.65, (vi) 0.78, (vii) 0.91, (viii) 1.03, (ix) 1.17, (x) 1.30, (xi) 1.43, (xii) 1.62,
(xiii) 1.81 and (xiv) 2.07. (b) Job’s plot for L with TBACl in [D6]DMSO ([L] is varied from 5.87 to 4.45 mm by the addition of aliquots
of 49.52 mm TBACl). (c) Plot showing change in the chemical shift of the NHa signal of L with increasing amounts of TBACl in [D6]-
DMSO at 298 K.
ments in dry acetonitrile at 298 K. Several attempts were
made to perform ITC titration experiments in a DMSO sol-
vent system, but we were unable to obtain any significant
heat change for the complexation of L with the various in-
vestigated anions. All the thermodynamic parameters are
tabulated in Table 2. Figure 3 represents the ITC titration
Table 1. Binding constants of L with various anions in [D6]DMSO
at 298 K.
–
–
–
Anions
F–
Cl–
Br–
I–/NO3
HSO4
2.83
H2PO4
2.20
logK
3.57
3.06
1.73 no binding
–
profiles of L with interacting anions F–, Cl–, Br–, H2PO4
and HSO4– as their tetrabutylammonium salts. The titration
profiles with other noninteracting weakly basic anions (I–
Solution-State ITC Studies
–
and NO3 ) are shown in the Supporting Information (Fig-
The detailed kinetic and thermodynamic parameters for
the binding of receptor L with various anions (F–, Cl–, Br–,
ure S15). For all interacting anions, we observed a strong
exothermic titration isotherm profile. Except for dihydrogen
–
–
–
I–, NO3 , H2PO4 , HSO4 ) were examined by ITC measure-
Figure 3. ITC titration profiles of L (0.1 mm) in acetonitrile at 298 K with (a) TBAF (1.12 mm), (b) TBACl (1.04 mm), (c) TBABr
(1.20 mm), (d) TBAHSO4 (1.61 mm) and (e) TBAH2PO4 (1.32 mm) guest anions.
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P. Bose, R. Dutta, S. Santra, B. Chowdhury, P. Ghosh
–
FULL PAPER
phosphate, the ITC titration profiles of L with other inter- binding trend follows the order F– Ͼ Cl– Ͼ HSO4
Ͼ
–
acting anions show 1:1 (host/guest) binding, which is evi- H2PO4 . This trend of the binding constant, obtained from
1
dent from the stoichiometry (n) (1.12 to 0.73) of the experi- ITC experiments, is well supported by H NMR titration
mental data (Table 2). Among the halides the more basic studies, even though the solvent systems are different.
F– shows a higher association constant than Cl– and Br–.
The binding of F– and Cl– with L in acetonitrile are high-
Solid-State Studies
enthalpy- and moderate-entropy-driven processes, whereas
in the case of Br– both the enthalpic and entropic contri-
bution is almost equal. The dissociation of the self-aggre-
gated 1D polymeric form of the free receptor L (evident
from the single-crystal X-ray structure) to its monomeric
form upon halide incorporation may be a plausible reason
for the positive value of entropy changes (ΔS), i.e. the sys-
tem becomes more disordered. Moreover, F– usually exists
in the hydrated form in TBAF and can also be solvated
easily in the moisture of the system. During the recognition
process of this ion, the receptor has to overcome the high
hydration energy of F–, which increases the overall entropy
of the system by releasing water molecules from the hy-
drated fluoride–water clusters. This may further contribute
to the positive entropy change of the binding process. In
Structural Description of L
The free receptor L crystallizes in a triclinic crystal sys-
¯
tem with a P1 space group. The single crystals of L suitable
for X-ray diffraction analysis are grown from an acetone/
water (1:1) solvent system. It has been found that one of
the sulfur atoms of the thiourea moiety of the receptor L is
hydrogen-bonded with another receptor molecule through
N–H···S hydrogen-bonding interactions (N3···S3 3.23 Å).
Thus, the receptor molecule propagates an infinite 1D array.
In addition, one of the nitrile groups of L is hydrogen-
bonded with the thiourea NH moiety of an adjacent recep-
tor unit through an N–H···N hydrogen-bonding interaction
(N2···N10 2.985 Å). Among the three thiourea units of L,
two units are directed toward the inner side of the receptor,
whereas the remaining one is positioned in the outward di-
rection. Interestingly, in the crystal structure two L recep-
tors form a sandwich-like molecular arrangement through
an S···S interaction with a measurable distance of 3.38 Å
(Figure 4).
–
–
the case of the oxyanions H2PO4 and HSO4 a different
trend in thermodynamic parameters is observed (Table 2).
In the case of these two anions, very high enthalpy values
compensate the high unfavourable entropy. One of the ex-
planations for the high negative entropy values in these
cases could be the formation of the more ordered dimeric
assembly of L upon tetrahedral anion encapsulation (evi-
dent from the single-crystal X-ray structure). Among the
investigated anions, F– shows the highest binding constant
value (logK = 7.02) in the acetonitrile solvent, and the
Structural Description of Complex 1
The asymmetric unit of the fluoride complex [nBu4N]·
[L(F)]·[CH3CN] (1) consists of one thiourea receptor L, one
encapsulated fluoride anion, one tetrabutylammonium
counter cation and one cocrystallised acetonitrile molecule.
The crystal structure of 1 clearly shows that the F– ion is
perfectly swallowed by the tripodal C3v-symmetric cavity of
receptor L through six N–H···F– hydrogen-bonding interac-
tions with six NH protons (Figure 5). The hydrogen-bond-
ing parameters are listed in Table S1 of the Supporting In-
formation. A correlation of N–H···F angles vs. H···F dis-
tances (Figure S19 and Table S1 of the Supporting Infor-
mation) reveals that all the hydrogen bonds fall in the
Table 2. Thermodynamic parameters of L for the binding of the
different anions in acetonitrile at 298 K.
Guest
n
TΔS
ΔH
ΔG
logK
[kcalmol–1] [kcalmol–1] [kcalmol–1]
F–
Cl–
Br–
0.75
1.12
1.12
3.16
3.72
3.66
–7.89
–17.94
–6.43
–5.49
–3.71
–15.36
–24.67
–9.59
–9.21
–7.37
–7.47
–6.73
7.02
6.76
5.41
5.47
4.93
–
HSO4 – 0.73
H2PO4 0.33
Figure 4. (a) Ball-stick representation of receptor L. (b) Ball-stick representation depicting the receptor dimer (non-acidic hydrogen atoms
are omitted for clarity).
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Binding and Extraction Studies by a Simple Tripodal Thiourea Receptor
Figure 5. (a) Ball-stick representation of complex 1 depicting the encapsulation of F– inside L. (b) The distorted trigonal-prismatic geome-
try around F–. (c) Space-filling representation of complex 1 (non-acidic hydrogen atoms and tetrabutylammonium counter cations are
omitted for clarity).
strong hydrogen-bonding interaction region of dH···F
Ͻ
Structural Description of Complex 2
2.2 Å and dN···F Ͻ 3.0 Å. The geometry around the encap-
sulated F– ion is distorted trigonal-prismatic. The torsional
angles are N5–Cg1–Cg2–N6 –2.28°, N2–Cg1–Cg2–N3
–1.58° and N8–Cg1–Cg2–N9 –1.03°, where Cg1 and Cg2
are the centroids of the plane containing the nitrogen atoms
N2, N5, N8 and N3, N6, N9, respectively (Figure S16 of
the Supporting Information). The average twist angle of
complex 1 is only –1.63°, which is close to the regular trigo-
nal-prismatic arrangement (ideal twist angle 0°). On the
other hand, our previous report of distorted trigonal-pris-
matic geometries around F– showed an average twist angle
of 4.28°.[13b] The N6F coordination sphere can be described
as two triangles constituted by (N2, N5, N8) and (N3, N6,
N9) with an average side (s) of 4.28 Å. The intertriangular
separation of the centroids of these two N3 triangles is
2.19 Å (h) (Figure S16 of the Supporting Information).
Thus, the s/h ratio of complex 1 is 1.95, which indicates an
elongation compared with an ideal trigonal prism (s/h =
1).[17]
The sulfate complex of the receptor L crystallizes as
[nBu4N]2·[2L(SO4)] (2) in the triclinic crystal system with a
P1 space group. Two units of L form a cavity that encapsu-
¯
lates a tetrahedral sulfate in its centre through hydrogen
bonding with six NH protons (Figure 6). There are a total
of 15 hydrogen-bonding interactions between the 12 NH
groups of two L units and four O atoms of the encapsulated
2–
SO4 ion. Three of the oxygen atoms, O1, O3 and O4, ac-
cept four hydrogen bonds each, and the remaining oxygen
atom (O2) forms three N–H···O contacts with the thiourea
protons of L. Thus, the tetrahedral sulfate anion induces a
tight dimeric capsular assembly of L, with an apical nitro-
gen distance measured as 9.51 Å (N···N). This type of sulf-
ate-assisted discrete tight capsular assembly of the tripodal
urea/thiourea-based receptor has previously been reported
with apical nitrogen distances (N···N) ranging from 9.18 Å
to 10.06 Å.[13b,14,15c] A correlation of the N–H···O angle vs.
H···O distance shows that in the strong hydrogen-bonding
Figure 6. (a) Ball-stick representation of complex 2 depicting the encapsulation of SO42– inside the receptor L. (b) Space-filling representa-
tion of complex 2 (non-acidic hydrogen atoms and tetrabutylammonium counter cations are omitted for clarity).
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P. Bose, R. Dutta, S. Santra, B. Chowdhury, P. Ghosh
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2–
Figure 7. (a) Ball-stick representation of complex 3 depicting the encapsulation of CO3 inside L. (b) Space-filling representation of
complex 3 (non-acidic hydrogen atoms and tetraethylammonium counter cations are omitted for clarity).
interaction region of dH···O Ͻ 2.5 Å and dN···O Ͻ 3.2 Å there nique. A recent report also shows the addition of an excess
are 12 contacts (Figure S20 of the Supporting Information). of TBACl with a tripodal hexakis(urea) receptor to extract
All the hydrogen-bonding interactions are listed in Table S2 SO42– from water using a liquid–liquid extraction process.[8]
of the Supporting Information. Out of 12 contacts only one In our typical extraction experiment, L (1 mmol) and TBAI
contact has an N–H···O angle smaller than 140°, which is (1 equiv.) were dissolved in a CHCl3 (5 mL) solution, fol-
N9–H9A···O4 with an N–H···O angle of 138°, and dN···O is lowed by the addition of a distilled water solution (5 mL)
2.21 Å. There are three more hydrogen-bonding interac- containing KF (10 equiv.). The biphasic solution was then
tions present in complex 2 in the weak interaction zone (2.5 stirred for 3 h and allowed to settle for 0.5 h. The separated
Ͻ dH···O Ͻ 2.80 Å and 3.2 Ͻ dN···O Ͻ 3.50 Å).
organic layer was then passed through silicone-treated
Whatmann 1PS filter paper. The organic layer was concen-
trated to dryness to obtain a white solid, which was further
Structural Description of Complex 3
Complex 3 crystallizes in the triclinic crystal system with washed several times with diethyl ether in order to get rid
¯
a P1 space group. The asymmetric unit of complex 3 con- of excess tetrabutylammonium iodide. This was then dried
tains two units of receptor L, one carbonate anion and under reduced pressure to obtain the extracted solid mass.
three tetraethylammonium counter cations, two of which The extracted solid was then characterized by several spec-
occupy special positions and thus contribute one unit of troscopic techniques e.g. 1H NMR and 19F NMR spec-
positive charge overall. The guest carbonate is embedded as troscopy as well as a single-crystal X-ray structural study
a sandwich aggregation of the receptor through 14 N–H···O of the crystals isolated from the extracted solid upon
interactions (Figure 7). The sandwich assembly of complex crystallization. Figure 8 represents the 1H NMR spectro-
3 is very much similar to that of the sandwich assembly of scopic studies performed on receptor L, the extracted mass
1
the free receptor molecules, with a slight difference in cavity and complex 1. The H NMR spectrum of the extracted
space. Two of the oxygen atoms (O1 and O3) of carbonate mass shows appreciable downfield chemical shifts of the
accept five hydrogen bonds each, while O2 accepts four N– thiourea NH protons (Δδ = 1.67 and 0.89 ppm) with respect
H···O bonds, resulting in a total of 14 hydrogen-bonding to receptor L, which is the same for complex 1. The 1:1
interactions. A correlation of the N–H···O angle vs. H···O complexation of L with tetrabutylammonium fluoride in
e
distance shows that 11 out of the 14 hydrogen bonds are in the extracted mass was confirmed by calculating the CH2
f
the strong hydrogen-bonding interaction region of dH···O
Ͻ
or CH2 integration of L to the δ protons of the tetrabut-
2.5 Å and dN···O Ͻ 3.2 Å (Figure S21 of the Supporting In- ylammonium counter cation (Figure S17 of the Supporting
1
formation). All hydrogen-bonding parameters are tabulated Information). In fact, the H NMR spectrum of complex 1
in Table S3 of the Supporting Information
perfectly matches that of the extracted mass in all respects.
This result clearly indicates the presence of pure F–-encap-
sulated L in the extracted mass. 19F NMR spectroscopy was
also employed in order to verify the chemical environment
of the fluoride in the extracted mass as well as in complex
1. Figure 9(i) describes the 19F NMR spectrum of only the
TBAF (δ = –109 ppm) solution in [D6]DMSO. A significant
downfield shift of about 32.4 ppm of the free F– signal is
observed when 1 equiv. of L is added to the above solution
containing 1 equiv. of TBAF salt. This huge change in the
Anion Extraction Studies
Fluoride Extraction Studies
The extraction of fluoride from an aqueous solution by
L was achieved by solubilizing L in CHCl3 in the presence
of TBAI as an anion exchanger (which also acts as a phase-
transfer agent) followed by a liquid–liquid extraction tech-
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Binding and Extraction Studies by a Simple Tripodal Thiourea Receptor
chemical shift clearly indicates a strong hydrogen-bonding nance signal (at δ = –76 ppm) observed for the 1:1 solution-
interaction of F– with the NH protons of L [Figure 9(ii)]. state complexation (Figure 9). This set of data further sup-
Further, the 19F NMR spectra of the extracted mass as well ports the F– complexation as well as the purity of the ex-
as that of complex 1 perfectly coincide with the F– reso- tracted mass. The solution-state extraction phenomenon of
F– is unambiguously verified by a single-crystal X-ray dif-
fraction study of the crystals obtained from the extracted
mass, which exactly matches with the crystallographic pa-
rameters of complex 1. Finally, the extraction efficiency was
calculated by weighing the pure extracted mass and verified
in triplicate. Repeated extraction experiments show 66–69%
extraction of fluoride (based on L) from aqueous solutions
(Table 3). In order to verify the extraction ability of L in
the presence of 1 equiv. of F– the above extraction method
was repeated in the presence of a 1:1 stoichiometric ratio of
L/KF. The average extraction efficiency of L toward fluo-
ride is estimated to be ca. 61% from three repetitive extrac-
tion experiments (Table 4).
Sulfate Extraction Studies
Similar to the fluoride extraction experiment, L (1 mmol)
and TBAI (1 equiv.) were dissolved in a CHCl3 solution
Figure 8. Partial 1H NMR spectra of (i) the free receptor L; (ii) the
extracted mass and (iii) complex 1 in [D6]DMSO at 298 K. α, β, γ
and δ denote the protons of the nBu4N cation in the extracted mass
and in complex 1.
(5 mL), followed by the addition of a distilled water solu-
tion (5 mL) containing K2SO4 (10 equiv.). The aqueous-or-
ganic biphasic solution was then stirred for 3 h after which
it was allowed to settle for 0.5 h. The separated organic
layer was then passed through silicone-treated Whatmann
1PS filter paper. The organic layer was concentrated to dry-
ness under reduced pressure and washed with diethyl ether
(20 mL, 3 times) and dried. The extracted mass was sub-
jected to various studies, e.g. 1H NMR and FTIR spec-
troscopy, PXRD and single-crystal X-ray diffraction studies
to establish whether the liquid–liquid extraction of sulfate
1
was successful. Figure 10 depicts the combined H NMR
1
spectra of L, the extracted mass and complex 2. H NMR
spectroscopic studies of the extracted mass show a signifi-
cant downfield chemical shift of the signals of both NH
protons (Δδ = 0.77 and 0.94 ppm) with respect to L. Signifi-
cant changes in chemical shifts of the signals of the NH
protons suggest encapsulation/binding of sulfate in the trip-
odal cleft of L through strong hydrogen-bonding interac-
tions. Similar downfield shifts of the signals of the thiourea
NH protons are also encountered in the 1H NMR spectrum
Figure 9. Partial 19F NMR spectra of (i) the TBAF solution;
(ii) TBAF in L solution (1:1); (iii) extracted mass and (iv) complex
1 in [D6]DMSO at 298 K (hexafluorobenzene as the external stan-
dard).
Table 3. Calculation of percentage of fluoride extraction (L/KF = 1:10).
No. of experiment Weight of L Weight of TBAI Weight of KF
Weight of extracted mass L·TBAF
% of extraction
(from extracted mass)
[mg]
[mg]
[mg]
[mg]
1
2
3
30.70
35.20
34.10
18.10
20.74
20.20
28.50
32.62
31.60
30.00
33.20
32.60
68.9
66.5
67.4
Table 4. Calculation of percentage of fluoride extraction (L/KF = 1:1).
No. of experiment
Weight of L Weight of TBAI Weight of KF Weight of extracted mass L·TBAF
% of extraction
(from extracted mass)
[mg]
[mg]
[mg]
[mg]
1
2
3
32.00
36.80
35.10
19.00
21.50
20.90
2.80
3.51
3.26
28.08
31.48
30.48
61.8
60.5
61.1
Eur. J. Inorg. Chem. 2012, 5791–5801
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5797

P. Bose, R. Dutta, S. Santra, B. Chowdhury, P. Ghosh
2–
FULL PAPER
of complex 2 [Figure 10(iii)], which clearly affirms the same precipitating SO4 from the CHCl3 solution of the ex-
2–
chemical environment around SO4 in the extracted mass. tracted mass as BaSO4 using an aqueous BaCl2 solution.
It is important to note that the integration of CH2e or CH2
Upon vigorous stirring, a white suspension is formed from
f
of L and the δ protons of the tetrabutylammonium cation the precipitation of BaSO4. The percentage of sulfate ex-
indicate a 2:1 involvement of L/sulfate in the extracted solid traction is calculated gravimetrically from the weight of the
(Figure S18 of the Supporting Information). To check the isolated BaSO4 (Table 5). From the gravimetric analysis it
bulk purity of the extracted mass we have performed pow- has been found that the average quantitative extraction of
der X-ray diffraction (PXRD) studies and compared the
data with the simulated diffraction pattern of the single
crystal of complex 2. The patterns of the extracted mass
show trends that are similar to that of the simulated pattern
of the single crystal of complex 2 (Figure 11), suggesting
that the bulk purity of the extracted solid corresponds to
2L·(TBA)2SO4. The comparative FTIR spectroscopy ex-
periments of complex 2 and the extracted mass show a
characteristic absorption peak at 1100 cm–1 (symmetric
stretching frequency of sulfate) in both cases (Figure 12).
The quantification of sulfate extraction is performed by
Figure 11. (a) PXRD pattern of the extracted mass (experimental
pattern) and (b) PXRD pattern of complex 2 (simulated).
Figure 10. Partial 1H NMR spectra of (i) the free receptor L;
(ii) the extracted mass and (iii) complex 2 in [D6]DMSO at 298 K.
α, β, γ and δ denote the protons of the nBu4N cation in the ex-
tracted mass and in complex 2.
Figure 12. FTIR analyses of L (red), complex 2 (green) and the
extracted mass (blue) using KBr discs.
Table 5. Calculation of the percentage of extracted sulfate from both the extracted mass and BaSO4 precipitation with respect to L
(gravimetrically) (L/K2SO4 = 1:10).
No. of experi- Weight
Weight of
TBAI
[mg]
Weight of ex-
tracted mass
[mg]
% of extraction (from
extracted mass)
Weight of
K2SO4
[mg]
Weight of % of extraction (from
ments
of L
[mg]
BaSO4
[mg]
BaSO4 mass)
1
2
3
34.40
36.25
34.20
20.20
21.35
20.20
29.50
30.20
28.20
44.6
43.2
42.7
96.50
100.90
95.20
5.50
5.75
5.00
42.8
42.5
39.2
Table 6. Calculation of percentage of extracted sulfate from both extracted mass and BaSO4 precipitation with respect to L (gravimetri-
cally) (L/K2SO4 = 1:1).
No. of experi-
ments
Weight
of L
[mg]
Weight of
TBAI
[mg]
Weight of ex-
tracted mass
[mg]
% of extraction (from
extracted mass)
Weight of
K2SO4
[mg]
Weight of
BaSO4
[mg]
% of extraction (from
BaSO4 mass)
1
2
3
34.80
35.50
35.20
20.80
20.90
20.70
23.14
23.52
23.10
34.3
34.4
34.1
9.67
9.85
9.76
4.20
4.35
4.26
32.3
32.8
32.4
5798
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5791–5801

Binding and Extraction Studies by a Simple Tripodal Thiourea Receptor
298 K in freshly dried acetonitrile solvent. In a typical ITC experi-
ment a solution of 0.1 mm of receptor L prepared in acetonitrile
was loaded in the measuring cell. This solution was then titrated
with 30 injections of 10 μL of ca. 1.5 mm tetrabutylammonium salts
sulfate by receptor L is 41.5% (based on L) observed from
three repeated experiments. Furthermore, the extraction
2–
efficiency of L towards SO4 in the presence of 1 equiv. of
2–
SO4 was repeated in the presence of a 1:1 stoichiometric
of F–, Cl–, Br–, I–, NO3 HSO4 and H2PO4 solutions prepared in
acetonitrile solvent. In all cases the anion under study was titrated
into the host solution. An interval of 220 s was allowed between
each injection, and the stirring speed was set at 329 rpm. The ob-
tained data were processed using the Origin 7.0 software supplied
with the instrument and fitted to a one-site binding model. The
initial study of the effect of the various salts was repeated three
times with L and showed good reproducibility. A blank titration of
tetrabutylammonium salts into a plain solvent was also performed
and subtracted from the corresponding titration to remove any ef-
fect from the heat of dilution from the titrant. In general, the stoi-
chiometry (n), association constants (K), change in enthalpy (ΔH)
and change in entropy (ΔS) values determined by these experiments
were within experimental error limits.
–
–
–
ratio of L/K2SO4. The average extraction efficiency of L
towards SO42– is estimated to be ca. 32.5% from gravimetric
analysis (Table 6). Thus, the liquid–liquid extraction tech-
nique has been successfully employed for the extraction of
2–
F– and SO4 by an anion-exchange strategy.
Conclusions
A simple tripodal thiourea receptor L displays different
modes of binding depending upon the topology of the in-
coming anionic guest. The receptor shows 1:1 encapsulation
of spherical fluoride, a dimeric sandwich assembly for the
planar carbonate (2:1) and tight dimeric capsular assembly
for tetrahedral sulfate (2:1). Interestingly, the tris(thiourea)
receptor shows a higher binding affinity toward spherical
halides over tetrahedral oxyanions in the solution state. Im-
portantly, this receptor has shown potential in the liquid–
liquid extraction of two biologically and environmentally
important anions, fluoride and sulfate, from aqueous solu-
tions using an anion-exchange strategy. Fluoride and sulfate
extraction were performed separately, and moderate extrac-
tion efficiencies of fluoride and sulfate were achieved.
X-ray Crystallography: A single crystal of suitable size was selected
from the mother liquor, immersed in paratone oil, then mounted
on the tip of a glass fibre, and cemented using epoxy resin. Intensity
data for these crystals were collected using Mo-Kα (λ = 0.7107 Å)
radiation with a Bruker SMART APEX II diffractometer equipped
with a CCD area detector. Reflections were measured from a hemi-
sphere of data collected with each frame covering 0.5° in ω. The
data integration and reduction were processed with the SAINT[18]
software provided with the software package SMART APEX II.
An empirical absorption correction was applied to the collected
reflections with the program SADABS.[19] The structures were
solved by direct methods using SHELXTL[20] and were refined on
F2 by the full-matrix least-squares technique using the SHELXL-
97[21] program package. Graphics were generated using
PLATON[22] and MERCURY 2.3.[23] In all cases, the non-hydrogen
atoms were refined anisotropically until convergence. All the hydro-
gen atoms were geometrically positioned and treated as riding
atoms.
Experimental Section
Materials and Methods: Tris(2-aminoethyl)amine, 4-cyanophenyl
isothiocyanate and all tetraalkylammonium salts were purchased
commercially and used without further purifications. All NMR
spectra were recorded with a Bruker 300 MHz and 500 MHz FT-
NMR spectrometer (model: DPX-300) in [D6]DMSO at 298 K.
HRMS measurements were carried out with a QTof-Micro YA 263
instrument. Elemental analyses were performed with a CHN 2400
Synthesis of L: 4-Cyanophenyl isothiocyanate (2.6 g, 20 mmol) was
dissolved in dry dichloromethane (DCM, 25 mL) under ice-cold
conditions in a 2-neck round-bottomed flask (100 mL) equipped
1
Ser II Elemental Analyzer. Chemical shifts for H and 13C NMR
with
a
dropping funnel. Tris(2-aminoethyl)amine (1.0 mL,
spectra are reported in parts per million (ppm), calibrated to the
residual solvent peak set, with coupling constants reported in Hertz
(Hz). Hexafluorobenzene was used as an external standard for all
19F NMR spectroscopic experiment.
6.5 mmol) was dissolved in dry DCM (25 mL) and was added drop-
wise with constant stirring. The resulting solution was stirred under
N2 at 0 °C for another 1 h. The clear solution was then stirred at
room temperature for 24 h. The white precipitate formed was fil-
tered off and washed with DCM twice and finally with diethyl
ether. The collected white precipitate was air-dried. The yield of L
was 98%. A single crystal of L suitable for X-ray diffraction analy-
sis was obtained by slow concentration of an acetone/water (1:1)
solution. 1H NMR (300 MHz, [D6]DMSO): δ = 2.77 (t, 6 H,
NCH2), 3.61 (t, 6 H, NCH2CH2), 7.70 (s, 12 H, aromatic H), 8.03
(s, 3 H, NHb), 9.99 (s, 3 H, NHa) ppm. 13C NMR (125 MHz, [D6]-
1H NMR Spectroscopic Studies: Binding constants were obtained
by 1H NMR (300 MHz Bruker) titrations of L with [nBu]4N+A–
(A = F, Cl, Br, HSO4, H2PO4) in [D6]DMSO at 298 K. The initial
concentration of L and anions were ca. 5 mm and 50 mm, respec-
tively. Tetramethylsilane (TMS) in [D6]DMSO was used as an in-
ternal reference, and each titration was performed by 15–24 mea-
surements at room temperature. All proton signals were referenced
to TMS. The association constant, K values, were calculated by
fitting the change in the NH and aryl CH chemical shifts with a
1:1 association model with nonlinear least-squares analysis for F–,
DMSO):
δ = 42.3, 52.2, 105.2, 119.6, 121.8, 133.3, 144.5,
180.5 ppm. HRMS (ESI-TOF): calcd. for C30H30N10S3 [M + Na+]
649.1817; found 649.1714. C30H30N10S3 (626.81): calcd. C 57.48, H
4.82, N 22.35; found C 57.42, H 4.80, N 22.41.
–
–
Cl–, Br–, H2PO4 and HSO4 . The equation Δδ = [([A]0 + [L]0
+
1/K) Ϯ {([A]0 + [L]0 + 1/K)2–4[L]0[A]0}1/2]Δδmax/2[L]0 was used to
determine the K values. All 19F NMR spectra were recorded at
500 MHz. Chemical shifts in ppm are relative to an external stan-
dard of hexafluorobenzene in [D6]DMSO at 298 K.
Synthesis of Complex 1: L (75 mg, 0.12 mmol) was dissolved in
MeCN (5 mL) in a beaker (25 mL). nBu4N+F– (ca. 94 mg, 3 equiv.)
was added to this solution, and the mixture was stirred and slightly
warmed for a few minutes. The resulting solution was filtered, and
the solvent was allowed to evaporate at room temperature. Colour-
less hexagonal crystals of the fluoride complex, [nBu4N]·[L(F)]·
[CH3CN] (1), suitable for X-ray diffraction studies were obtained
Isothermal Titration Calorimetric (ITC) Studies: The isothermal ti-
tration calorimetric (ITC) experiments were performed with a
MicroCal VP-ITC instrument. All titrations were carried out at
Eur. J. Inorg. Chem. 2012, 5791–5801
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5799

P. Bose, R. Dutta, S. Santra, B. Chowdhury, P. Ghosh
Crystallographic Data for Complex 2: C92H132N22O4S7, Mr
(300 MHz, [D6]DMSO): δ = 0.921 (t, 12 H, NCH2CH2CH2CH3), 1834.62 gmol , triclinic, space group P1, a = 13.818(4) Å, b =
1.23–1.33 (m, H, NCH2CH2CH2CH3), 1.55 (m, H, 13.844(6) Å, c = 15.842(5) Å, α = 92.917(12)°, β = 106.547(8)°, γ =
NCH2CH2CH2CH3), 2.67 (s, H, NCH2), 3.14 (m,
H, 119.914(7)°; V = 2449.3(14) Å3, Z = 1, ρcalcd. = 1.244 gcm–3, μ =
NCH2CH2CH2CH3), 3.58 (s, 6 H, NCH2CH2), 7.64 (d, J = 8.1 Hz, 0.222 mm–1, T = 170(2) K, 8550 reflections, 2605 independent (Rint
FULL PAPER
after 3 d. The isolated yield of complex 1 was 80 %. 1H NMR
=
–1
¯
8
8
8
6
6 H, aromatic-Hd), 7.83 (d, J = 9.0 Hz, 6 H, aromatic-Hc), 8.83
= 0.0886) and 1770 observed reflections [IՆ2σ(I)], 572 refined pa-
(br., 3 H, NHb), 11.52 (br., 6 H, NHa) ppm. 13C NMR (125 MHz, rameters, R1 = 0.0531, wR2 = 0.1341, GOF = 1.022.
[D6]DMSO): δ = 14.1, 19.8, 23.7, 40.8, 50.7, 58.2, 104.4, 119.8,
Crystallographic Data for Complex 3: C153H160N45O6S12, Mr
=
120.6, 133.2, 145.5, 180.4 ppm. 19F NMR (500 MHz, [D6]DMSO):
–1
¯
3109.98 gmol , triclinic, space group P1, a = 14.010(2) Å, b =
14.174(2) Å, c = 25.178(4) Å, α = 84.894(5)°, β = 74.556(4)°, γ =
64.294(4)°, V = 4340.6(12) Å3, Z = 1, ρcalcd. = 1.190 gcm–3, μ =
0.215 mm–1, T = 150(2) K, 28969 reflections, 9539 independent
(Rint = 0.0992) and 6189 observed reflections [IՆ2σ(I)]; 978 refined
parameters; R1 = 0.0584, wR2 = 0.1542, GOF = 1.040.
δ = –76.27 ppm. C46H66FN11S3·H2O (906.29): calcd. C 60.96, H
7.56, N 17.00, S 10.61; found C 61.02, H 7.80, N 16.77, S 10.42.
Synthesis of Complex 2: Complex 2 was synthesized by treating L
with nBu4N+HSO4 . L (ca. 75 mg, 0.12 mmol) was dissolved in
–
DMSO (10 mL) in a beaker (25 mL), and nBu4N+HSO4 (ca.
–
122 mg, 3 equiv.) was added. The mixture was then stirred at room
temperature for 5 min and warmed at 60 °C for 10 min. After cool-
ing to room temperature, the resulting solution was filtered and
the complex allowed to crystallize at room temperature. Colourless
crystals of the sulfate complex of L, [2(nBu)4N]·[2L(SO4)] (2), suit-
able for an X-ray diffraction study were obtained after 1 week. The
isolated yield of complex 2 was 60 %. 1H NMR (300 MHz, [D6]-
DMSO): δ = 0.92 (t, 12 H, NCH2CH2CH2CH3), 1.25–1.33 (m, 8
H, NCH2CH2CH2CH3), 1.55 (m, 8 H, NCH2CH2CH2CH3), 2.64
(s, 6 H, NCH2), 3.14 (m, 8 H, NCH2CH2CH2CH3), 3.54 (s, 6 H,
NCH2CH2), 7.60 (d, J = 9.3 Hz, 6 H, aromatic Hd), 7.85 (d, J =
8.4, Hz, 6 H aromatic Hc), 8.93 (br., 3 H, NHb), 10.72 (br., 6 H,
NHa) ppm. 13C NMR (125 MHz, [D6]DMSO): δ = 13.5, 19.3, 23.1,
42.0, 53.2, 57.6, 104.1, 119.3, 121.4, 132.3, 144.8, 179.9 ppm.
C92H132N22O4S7 (1834.62): calcd. C 60.23, H 7.25, N 16.80, S
12.23; found C 60.11, H 7.16, N 16.72, S 12.32.
CCDC-875997 (for L), -875998 (for 1), -875999 (for 2) and -876000
(for 3) contain the supplementary crystallographic data for this pa-
per. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Supporting Information (see footnote on the first page of this arti-
cle): All the characterization data, 1H NMR titration data, ITC
titration data and all the crystallographic parameters.
Acknowledgments
P. G. gratefully acknowledges the Department of Science and Tech-
nology (DST), New Delhi, India for financial support through a
Swarnajayanti Fellowship. P. B., R. D., S. S. and B. C. would like
to acknowledge the Council of Scientific and Industrial Research
(CSIR), New Delhi, India for research fellowships. The X-ray crys-
tallographic study was performed at the DST-funded National Sin-
gle-Crystal X-ray Diffraction Facility at the Department of Inor-
ganic Chemistry, IACS.
Synthesis of Complex 3: Complex 3 was synthesized by treating L
–
with Et4N+HCO3 . L (ca. 75 mg, 0.12 mmol) was dissolved in
–
DMSO (10 mL) in a beaker (25 mL). Et4N+HCO3 (ca. 68 mg,
3 equiv.) was added to the solution. The mixture was then stirred
at room temperature for 5 min and warmed to 60 °C for 10 min.
After cooling to room temperature, the resulting solution was fil-
tered, and the complex was allowed to crystallize under ambient
conditions. From the solution colourless crystals of the carbonate
complex of L, [2Et4N]·[2L(CO3)] (3), suitable for X-ray diffraction
studies were obtained after 1 week. The isolated yield of complex
[1] a) F. Hofmeister, Arch. Exp. Pathol. Pharmakol. 1888, 24, 247–
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1
3 was 50 %. H NMR (300 MHz, [D6]DMSO): δ = 1.50 (t, 12 H,
NCH2CH3), 2.64 (s,
6 H, NCH2), 3.17–3.21 (m, 8 H,
NCH2CH2CH3), 3.55 (s, 6 H, NCH2CH2), 7.57 (d, J = 8.5 Hz, 6
H, aromatic Hd), 7.81 (d, J = 7.0 Hz, 6 H, aromatic Hc), 9.23 (br.,
3 H, NHb) ppm. 13C NMR (125 MHz, [D6]DMSO): δ = 7.6, 42.2,
52.1, 52.8, 104.4, 119.9, 122.0, 132.7, 145.7, 180.4 ppm.
C77H100N22O3S6 (1574.14): calcd. C 58.75, H 6.40, N 19.58, S
12.22; found C 58.60, H 6.27, N 19.44, S 12.05.
[3] a) R. Hu, J. Feng, D. Hu, S. Wang, S. Li, Y. Li, G. Yang,
Angew. Chem. 2010, 122, 5035; Angew. Chem. Int. Ed. 2010,
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uly, A. Das, Chem. Commun. 2011, 47, 7398–7400.
Crystallographic Data for L: C30H30N10S3, Mr = 626.82 gmol–1,
¯
[5] a) J. L. Sessler, S. K. Kim, D. E. Gross, C.-H. Lee, J. S. Kim,
V. M. Lynch, J. Am. Chem. Soc. 2008, 130, 13162–13166; b) A.
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[7] a) B. A. Moyer, P. Bronnesen, Physical Factors in Anion Separa-
tions, in the Supramolecular Chemistry of Anions (Eds.: A. Bian-
chi, K. Bowman-James, E. García-España), VCH, Weinheim,
Germany, 1997, chapter 1, pp. 1–44; b) B. A. Moyer, R. P.
Singh, Fundamental and Application of Anion Separation,
Kluwer Academic/Plenum, New York, 2004; c) L. R. Eller, M.
triclinic, space group P1, a = 10.2239(13) Å, b = 12.635(2) Å, c =
13.4504(13) Å, α = 70.203(3)°, β = 70.124(2)°, γ = 70.677(2)°, V =
1491.1(3) Å3, Z = 2, ρcalcd. = 1.396 gcm–3, μ = 0.289 mm–1, T =
150(2) K, 15699 reflections, 6126 independent (Rint = 0.0584), and
4780 observed reflections [IϾ2σ(I)], 388 refined parameters, R1 =
0.0408, wR2 = 0.0899, GOF = 1.031.
Crystallographic Data for Complex 1: C48H69FN12S3, Mr
=
–1
¯
929.36 gmol , triclinic, space group P1, a = 12.7662(7) Å, b =
13.0257(8) Å, c = 18.5609(15) Å, α = 103.861(2)°, β = 94.501(2)°, γ
= 119.300(1)°, V = 2542.5(3) Å3, Z = 2, ρcalcd. = 1.214 gcm–3, μ =
0.195 mm–1, T = 150(2) K, 24172 reflections, 9289 independent
(Rint = 0.0492) and 8887 observed reflections [IՆ2σ(I)], 564 refined
parameters, R1 = 0.0374, wR2 = 0.1031, GOF = 1.017.
5800
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 5791–5801

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Received: July 11, 2012
Published Online: October 9, 2012
Eur. J. Inorg. Chem. 2012, 5791–5801
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