Thermodynamics of host-guest interactions between methylpyridinium salts and phosphonate cavitands

Article abstract of DOI:10.1080/10610278.2010.506547

In this work, the properties of complexation of tetraphosphonate cavitands towards methylpyridinium guests were investigated via isothermal titration calorimetry (ITC). For this purpose, Tiiii[C₃H₇, CH ₃, Ph], Tiiii[C

Full text of DOI:10.1080/10610278.2010.506547

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Thermodynamics of host–guest interactions between
methylpyridinium salts and phosphonate cavitands
a
a
b
c
Daniela Menozzi , Elisa Biavardi , Chiara Massera , Franz-Peter Schmidtchen , Andrea
d
a
Cornia & Enrico Dalcanale
a
Dipartimento di Chimica Organica e Industriale & INSTM , Università di Parma , Viale G.P.
Usberti 17/A, 43124, Parma, Italy
b
Dipartimento di Chimica Generale e Inorganica, Chimica Analitica, Chimica Fisica ,
Università di Parma , Viale G.P. Usberti 17/A, 43124, Parma, Italy
c
Department Chemie , Technische Universität München , D-85747, Garching, Germany
d
Dipartimento di Chimica & INSTM , Università di Modena e Reggio Emilia , Via G. Campi
183, 41100, Modena, Italy
Published online: 24 Aug 2010.
To cite this article: Daniela Menozzi , Elisa Biavardi , Chiara Massera , Franz-Peter Schmidtchen , Andrea Cornia & Enrico
Dalcanale (2010) Thermodynamics of host–guest interactions between methylpyridinium salts and phosphonate cavitands,
Supramolecular Chemistry, 22:11-12, 768-775, DOI: 10.1080/10610278.2010.506547
To link to this article: http://dx.doi.org/10.1080/10610278.2010.506547
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Supramolecular Chemistry
Vol. 22, Nos. 11–12, November–December 2010, 768–775
Thermodynamics of host–guest interactions between methylpyridinium salts and phosphonate
†
cavitands
a
a
b
c
d
a
Daniela Menozzi , Elisa Biavardi , Chiara Massera , Franz-Peter Schmidtchen , Andrea Cornia and Enrico Dalcanale *
a
Dipartimento di Chimica Organica e Industriale & INSTM, Universit a` di Parma, Viale G.P. Usberti 17/A, 43124 Parma, Italy;
Dipartimento di Chimica Generale e Inorganica, Chimica Analitica, Chimica Fisica, Universit a` di Parma, Viale G.P. Usberti 17/A,
b
c
d
3124 Parma, Italy; Department Chemie, Technische Universit a¨ t M u¨ nchen, D-85747 Garching, Germany; Dipartimento di Chimica &
4
INSTM, Universit a` di Modena e Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy
(
Received 18 May 2010; final version received 24 June 2010)
In this work, the properties of complexation of tetraphosphonate cavitands towards methylpyridinium guests were
investigated via isothermal titration calorimetry (ITC). For this purpose, Tiiii[C , CH , Ph], Tiiii[C , H, Ph],
TSiiii[C H , H, Ph] hosts and three different methylpyridinium guests were synthesised. The role of the following
3
H
7
3
3 7
H
3
7
parameters in the host–guest complexation was investigated: (i) solvation, (ii) nature of the guest counterion, (iii) presence
of substituents in the apical positions of the receptor, and (iv) PvO versus PvS bridging units. The results showed that (i)
switching from dichloroethane to methanol leads to a decrease of the association constant due to the competitive nature of
the solvent, (ii) the guest counterion does not affect the thermodynamics of the process, (iii) the apical methyl groups
enhance the binding affinity of the receptor and (iv) the comparison between phosphonate and thiophosphonate hosts clearly
demonstrates that cation–dipole interactions are necessary for binding.
Keywords: tetraphosphonate cavitands; methylpyridinium salts; host–guest complexation; ITC
1
.
Introduction
methylpyridinium salts (11) and even higher for N,N-
methylalkylammonium salts (4).
Phosphonate cavitands have established themselves as one
of the most promising classes of molecular receptors (1),
thanks to their diversified complexation properties,
spanning from cationic species such as ammonium,
methylpyridinium and inorganic salts to neutral guests
such as alcohols. In particular, their complexation prowess
towards methylpyridinium salts has been exploited in the
generation of functional surfaces (2, 3) and supramole-
cular polymers (4). The key player of the whole class is the
tetraphosphonate cavitand Tiiii (5, 6), presenting all four
PvO bridging groups oriented inward with respect to the
cavity (7) (see Chart 1). Its peculiar complexation ability is
the result of three interaction modes, which can be
activated either individually or in combination by the host
according to the following guest requirements: (i) multiple
ion–dipole interactions between the inward-facing PvO
groups and the positively charged guests (8); (ii) single or
multiple H-bonding involving the PvO groups (9) and
An understanding of the intimate features of the host–
guest interactions and their thermodynamic signatures is
essential in order to optimise selectivity and strength in
3
1
guest uptake. In this case, P NMR is a diagnostic tool to
assess complexation in solution due to the presence on the
host of four interacting PvO units. However, in the case
of methylpyridinium guests, the association constants
exceed the upper limit revelation of the NMR
4
21
(
10 , Kass , 10 M ). In this situation, isothermal
titration calorimetry (ITC) represents the best alternative
because it can determine association constants within the
2
range 10 , K , 10 M
7
21
(12, 13), and it provides
ass
directly the thermodynamic parameters in the form of Kass,
DH, DS, DG and DCp.
This article reports an ITC study of the influence of
the following parameters on the properties of complexa-
tion of the four tetraphosphonate/thiophosphonate
cavitands reported in Chart 1 towards methylpyridinium
guests: (i) solvation, (ii) nature of the guest counterion,
(iii) presence of substituents in the apical positions of the
receptor and (iv) PvO versus PvS bridging units.
(iii) CH –p interactions between an acidic methyl group
3
present on the guest and the p-basic cavity of the host (10).
Depending on the type and number of interactions
activated, the measured K in non-polar solvents can
ass
2
vary from 10 M for short-chain alcohols to 10 M for
21
7
21
*
Corresponding author. Email: enrico.dalcanale@unipr.it
†
Dedicated to the memory of Dmitry Rudkevich.
ISSN 1061-0278 print/ISSN 1029-0478 online
q 2010 Taylor & Francis
DOI: 10.1080/10610278.2010.506547
http://www.informaworld.com

Supramolecular Chemistry
769
O
O O
O
O
O O
O
P
O
P
P
P
O
P
P
P
O
P
O
O
O
O
O
O
O
O
O
O
O
O
O
Tiiii[C H , CH , Ph]
Tiiii[C H , H, Ph]
3 7
3
7
3
S
S S
S
P
O
P
P
P
O
O
O
O
O
O
O
TSiiii[C H , H, Ph]
3
7
HO
O
O
O
O
HO
OH
N+
N+
N+
I–
I–
–
PF6
CH3
CH3
CH3
1
2
3
Chart 1. Cavitand hosts and methylpyridinium guests utilised in the present work.
2
.
Results and discussion
solid state is proven by the crystal structure of Tiiii[C H ,
3 7
CH , Ph]·(C H INO )·5CH CN complex (Figure 1).
3
The preparation of cavitand Tiiii[C H , CH , Ph] has
3
3
10 16
3
7
3
The presence of the four apical methyl substituents does
not change stoichiometry and complexation mode with
respect to the parent Tiiii[C H , H, Ph] cavitand (2).
already been reported (11). Cavitands Tiiii[C H , H, Ph]
3
7
and TSiiii[C H , H, Ph] were prepared via a two-step
3
7
procedure. The acid-catalysed condensation between
resorcinol and butyraldehyde led to the propyl-footed
resorcinarene Res[C H , H], which was then bridged with
2
5
The reported crystal structure evidences the different
synergistic interactions between the tetraphosphonate
cavitand Tiiii[C H , CH , Ph] and guest 1 (see Figure 1,
3
7
dichlorophenylphosphine and oxidised in situ either with
hydrogen peroxide or with S to give Tiiii[C H , H, Ph]
and TSiiii[C H , H, Ph], respectively (Scheme 1). The
3
7
3
left). The inclusion of 1 in the cavity is driven by dipolar
interactions between the positively charged nitrogen atom
and two PvO groups at the upper rim of the cavitand
8
3
7
3
7
methylpyridinium guests 1–3 reported in Chart 1 were all
prepared via alkylation of the corresponding pyridine
precursors with methyl iodide, followed by anion
exchange with NH PF in the case of guest 3.
þ
˚
(PvOzzzN : 3.056(3) and 3.116(3) A). One of these PvO
moieties is also involved in a hydrogen bond with an OH
˚
group of the guest (OzzzOvP 2.992(4) A and OZH OvP
4
6
The determination of the thermodynamic data from the
ITC curves requires the knowledge of the binding
stoichiometry of the formed complex. In our case, clearly
evident 1:1 binding was in the solid state (2), and in
solution (11) for ester derivatives 2–3 with the Tiiii hosts.
For triol-substituted guest 1, the 1:1 stoichiometry in the
170.4(2)8). Further stabilisation is provided by three
CZH· · ·p interactions between the methyl hydrogens of
the cation and three aromatic rings of the cavity (the
C–H· · ·centroid distances are 2.667(4), 2.828(3) and
˚
3.129(2) A, with angles 126.44(3), 136.15(2) and
166.64(1)8, respectively). The iodide counterion is located

7
70
D. Menozzi et al.
Ph
O
P
Ph
O
P
O
O
O
O
R
R
R
R
Tiiii[C H , H, Ph]
3
7
HO
OH
HO
HO
OH
OH
O
O
O
O
R
R
R
R
P
P
O
O
Ph
Ph
HO
OH
Res[C H , H]
Ph
O
P
Ph
O
P
3
7
S
S
O
O
R
R
R
R
TSiiii[C H , H, Ph]
3
7
O
S
O
S
P
P
O
O
Ph
Ph
Scheme 1. Synthesis of Tiiii[C H , H, Ph] and TSiiii[C H , H, Ph] cavitands.
3
7
3 7
˚
below the cavity at 1.808(2) A from the least-square plane
˚
to 3.1674(5) A. The iodide ion also forms two hydrogen
bonds (one stronger and one weaker) with two OH groups
2
defined by the four CH carbons, roughly in the middle of
2
the four alkyl chains at the lower rim. This position is
2
of the guest of a neighbouring complex (O· · ·I 392(2) and
2
3.563(4) A; O–H· · ·I 166.8(1) and 165.9(2)8, respect-
˚
stabilised by four C–H· · ·I interactions with the first CH
2
groups of the chains, which range in length from 2.9985(5)
ively). This influences the crystal packing which shows a
3 7 3 3 3
Figure 1. Crystal structure (left) and crystal packing (right) of Tiiii[C H , CH , Ph]·(C10H16INO )·5CH CN complex. Colour code:
I, purple; P, orange; O, red; C, grey; H, white. H-bonding, green line; CH –p interactions, blue line. Hydrogen atoms, except for the
3
triol, and acetonitrile solvent molecules are omitted for clarity.

Supramolecular Chemistry
771
d
d

7
72
D. Menozzi et al.
typical columnar disposition along the a-axis of the unit
2
cell (see Figure 1, right). The distance between I and the
entropy driven. As shown in Table 1 (entries III and IV),
the thermodynamic parameters of Tiiii[C H , H, Ph]
3
7
˚
positive nitrogen of the guest is 7.679(3) A. All the above
complexation in DCE are not influenced by the
counterions, confirming the results reported for the
parent Tiiii[C H , CH , Ph].
values are in good agreement with similar complexes
reported in the literature (2, 14).
3
7
3
The first set of ITC measurements was made to assess
the solvent effect on the complexation. For this purpose,
dichloroethane (DCE) and methanol were chosen. The
former does not compete for the cavity due to its size and
its low propensity to form hydrogen bonds with the PvO
units of the cavitand. Vice versa, in the case of methanol,
crystal structures showed its inclusion in the cavity of Tiiii
receptors (10), driven by the synergistic action of
In order to probe the contribution of cation–dipole
interactions on the overall binding, tetrathiophosphonate
cavitand TSiiii[C H , H, Ph] was prepared (Scheme 1). It
3
7
is structurally identical to the corresponding tetrapho-
sphonate Tiiii[C H , H, Ph], except for the presence of
3
7
four inward-facing PvS instead of four PvO bridging
units. The PvS group is more polarisable than the PvO
counterpart, but it has a much smaller dipole moment (16).
Its larger size does not preclude the insertion of methyl
groups into the cavity (17); therefore, the introduction of
four PvS bridges has little influence on CH–p
interactions. As a corollary, this substitution should
decrease substantially the cation–dipole interactions
with the charged methylpyridinium guests. The ITC
results were beyond our expectations: the affinity of the
cavitand for guests 2 and 3 was completely shut off (Table
1, entries V and VI). Therefore, the cation–dipole
interactions are indispensable for binding methylpyridi-
nium guests. Without PvO, the complexation is
negligible, well below the detection limit of ITC.
H-bonding with the phosphonates and CH –p interactions
3
with the cavity. The different affinity of the two solvents
for the cavity is clearly reflected in the complexation of
guests 2 and 3 by Tiiii[C H , CH , Ph]. A decrease of the
3
7
3
association constant of two orders of magnitude was
determined for both guests by moving from DCE to MeOH
(
Table 1, entries I and II). In both cases, the reduced
affinity in MeOH is mainly enthalpic in origin, with the
DH reduction attributable to the solvent competition for
the cavity and the electrostatic stabilisation of the cationic
guest by the more polar solvent. Interestingly, the
counterion does not influence complexation, leading to
comparable values of DG and K . Such unexpected
ass
silence in impact may be attributed to the preferential
2
positioning of both iodide and PF within the alkyl chains,
6
3
.
Conclusions
as was proven in NMR studies in chloroform (14). Yet, the
absence of evidence of a role for the counterions in the
binding process can also arise from an adventitious
cancellation of enthalpic and entropic effects of com-
plexation at the less structured, well-solvated and solvent-
like site of the host compound.
The selective complexation of methylpyridinium salts by
tetraphosphonate cavitands relies on two interactions,
namely cation–dipole and CH –p, which operate
3
synergically. The crystal structure of the reported
complex clearly evidences this synergy in the solid
state. Using ITC, the thermodynamic profile in the
formation of several host–guest complexes was deter-
mined. They all are driven both by enthalpy and entropy
(18, 19), reflecting the importance and substantial
participation of solvent interactions for the binding
process. The relative weights of the two direct mutual
interaction modes have been dissected by changing two
structural parameters on the cavitands. The dominant role
of cation–dipole interactions was revealed by substituting
the PvO bridges with the PvS ones, which completely
suppressed complexation. The relevance of CH–p
interactions was highlighted by the removal of the four
methyl groups in the cavity apical positions, which led to
the decrease of one order of magnitude in the Kass of both
2 and 3. On the guest side, the counterion does not play a
significant role in complexation, which can be due to an
adventitious cancellation of effects, but may also emerge
from the basic lack of binding. The solvent instead affects
the binding significantly, particularly when the solvent
competes with the guest for the cavity space, like in the
case of methanol.
Next, the role of the cavity structure on complexation
was investigated. The presence of four methyl groups in
the apical positions of Tiiii[C H , CH , Ph] deepens the
3
7
3
cavity and enhances its p-basic character. Their removal
should reduce the complexation efficiency of the receptor.
Experimentally, a decrease of the Kass of one order of
magnitude was observed for the titration of methyl-
depleted cavitand Tiiii[C H , H, Ph] with guests 2 and 3
3
7
in DCE, as compared to the original ones (Table 1,
compare entry I with entry III, and entry II with entry IV).
A large enthalpic drop was determined, only partially
compensated by an entropic gain. This is ascribed to the
reduced contribution of CH –p interactions (15) to the
3
overall binding and to the enhanced solvation of the more
open cavity of the demethylated host Tiiii[C H , H, Ph].
3
7
The latter origin is also suggested by the entropic
outcome which testifies to more dramatic cavity
desolvation and guest mobility in the case of Tiiii[C3-
H , H, Ph] upon binding, while the guest desolvation is
7
comparable in the two cases. It is worth noting that the
methylpyridinium binding remains both enthalpy and

Supramolecular Chemistry
773
1
4
.
Experimental
H NMR (300 MHz, CDCl ): d (ppm) 8.09 (m, 8H,
3
POArH ); 7.61 (m, 4H, POArH ); 7.52 (m, 8H, POArH );
o
4
.1 General methods
p
m
7.13 (s, 4H, ArHdown); 6.51 (s, 4H, ArH ); 4.81 (t, 4H,
up
All commercial reagents were ACS reagent grade and
were used as received, except for 4-picoline which was
purified by fractional distillation before use. Solvents were
J ¼ 7.4 Hz, ArCH); 2.34–2.20 (m, 8H, CH CH CH );
2
2
3
1
.41 (m, 8H, CH CH CH ); 1.04 (t, 12H, J ¼ 7.4 Hz,
2
2
3
3
1
CH CH CH ). P NMR (162 MHz, CDCl ) d (ppm): 4.02
(
1
2 2 3 3
dried and distilled using standard procedures. H NMR
s, 4P). ESI-MS: m/z 1167.3 [M þ Na]þ.
spectra were recorded on Bruker Avance 300 (300 MHz)
and on Bruker FT-DPX b200 NMR spectrometers. All
chemical shifts (d) were reported in parts per million
4.3 Cavitand TSiiii[C H , H, Ph]
3 7
(
ppm) relative to proton resonances resulting from
3
1
To a solution of resorcinarene Res[C H , H] (2.26 g,
3
incomplete deuteration of NMR solvents. P NMR
spectra were recorded on AMX-400 (162 MHz), and all
chemical shifts were reported to external 85% H PO at
7
3.5 mmol) dissolved in 20 mL of freshly distilled pyridine,
dichlorophenylphosphine (1.93 mL, 14.3 mmol) was
slowly added at room temperature. The mixture was
stirred for 3 h at 808C and then cooled to room
3
3
0
ppm. Electrospray ionisation mass spectrometry (ESI-
MS) experiments were performed on a Waters ACQUI-
LITY UPLC SQ Detector. ITC measurements were
performed with a fully computer-operated MicroCal
ITC-MCS instrument at 303 K by adding 2–10 mL
aliquots of the guest solution into the thermostated
solution of the host compound present in about 10-fold
lower concentration in the calorimetric cell (1.35 mL).
To obtain a good quality data output, it is essential to
choose the best experimental conditions. One adjustable
parameter that needs optimal setting is the c parameter:
temperature. S (0.72 g, 2.81 mmol) was added and left
8
stirring for 1 h at 508C. The solvent was removed in
vacuum followed by the addition of 50 mL of water, and
the yellow suspension was filtered. Purification by column
chromatography on silica gel with CH Cl :hexane (9/1
2
2
v/v) yielded the product (2.62 g, 62%).
1
H NMR (300 MHz, CDCl ): d (ppm) 8.19 (m, 8H,
3
POArH ); 7.60 (m, 4H, POArH ); 7.51 (m, 8H, POArH );
o
p
m
7.21 (s, 4H, ArHdown); 6.50 (s, 4H, ArH ); 4.72 (t, 4H,
up
J ¼ 7.8–Hz, ArCH); 2.31 (m, 8H, CH CH CH ); 1.40 (m,
2
2
3
8
H, CH CH CH ); 1.02 (t, 12H, J ¼ 7.2–Hz, CH CH -
2
2
3
2
2
3
1
c ¼ n £ ½AꢀKass;
CH ). P NMR: (172 MHz, CDCl ): d (ppm) 72(s, 4P).
ESI-MS: m/z: 1231.3 [M þ Na] .
3
3
þ
where n is the stoichiometric factor, [A ] is the
concentration of the titrate compound in the cell (M) and
2
1
4.4 2-(Hydroxymethyl)-2-(pyridin-4-yl)-
,3-propanediol (I)
Kass is the affinity constant (M ). In order to obtain a
sigmoidal output curve from which the Kass, the
stoichiometric factor n and the DH are derived, the c
parameter should be set within the range 5–500. Adjusting
the titrate concentration is the key factor to reach a good
shaped curve.
1
The following procedure (Scheme 2) improves the method
proposed by Koenigs and Happe (21). 4-Picoline (2.00 g,
21.5 mmol) was refluxed in 37% aqueous formaldehyde
(27 mL, 360 mmol) for 24 h. The solvent and excess
formaldehyde were removed under reduced pressure at
508C. Methanol (50 mL) was added to the residue and
removed under vacuum at 508C, and the procedure was
repeated. The crude product was subjected to prolonged
vacuum pumping (1 mmHg, 3 h), and purified by column
Cavitand Tiiii[C H , CH , Ph] (11), resorcinarene
3
7
3
Res[C H , H] (20), and guests 2 (3) and 3 (11) were
3
7
prepared following a published procedure.
4
.2 Cavitand T [C H , H, Ph]
iiii
chromatography (CH
2
Cl
2
:CH
3
OH 8/2 v/v) to afford the
3
7
To a solution of resorcinarene Res[C H , H] (517 mg,
3
7
0
.80 mmol) in freshly distilled pyridine (20 mL), dichlor-
HO
ophenylphosphine (0.447 mL, 3.39 mmol) was added
slowly at room temperature. After 3 h of stirring at 808C,
the solution was allowed to cool to room temperature, and
HO
HO
OH
CH3
HO
OH
O
8
mL of a mixture of 35% H O and CHCl (1:1) was
2 2 3
added. The resulting mixture was stirred for 30 min at
room temperature; then, the solvent was removed under
reduced pressure and water was added. The precipitate
obtained in this way was collected by vacuum filtration,
and purified by recrystallisation (H O:CH CN 8:2). The
CH3I
Acetone
H
H
N+
H O, CH3OH
2
I–
N
N
CH3
I
1
2
3
product is a fine white powder (870 mg, 95%).
Scheme 2. Synthesis of triol guest 1.

7
74
D. Menozzi et al.
desired compound as a white crystalline solid (2.25 g,
7%).
in Table 2. Intensity data and cell parameters were
recorded at 173 K on a Bruker AXS Smart 1000 single-
crystal diffractometer (employing a MoK radiation and a
5
1
H NMR (200 MHz, CD OD): d (ppm) 3.93 (s, 6H,
3
a
CH ); 7.54 (m, 2H, CH meta to N); 8.45 (m, 2H, CH ortho
2
CCD area detector). The raw frame data were processed
using SAINT and SADABS to yield the reflection data file
to N).
(
SIR97 program (23), and refined on F by full-matrix
22). The structure was solved by direct methods using the
2
o
4
1
.5 4-[1,3-Dihydroxy-2-(hydroxymethyl)propan-2-yl]-
-methylpyridinium iodide (1)
least-squares procedures using the SHELXL-97 program
(24). The PLATON/SQUEEZE procedure (25) was used to
treat regions of diffuse solvent, which could not be
sensibly modelled in terms of atomic sites. Their
contribution to the diffraction pattern was removed, and
Compound I (0.100 g, 0.546 mmol) was suspended in
acetone (3 mL), and MeI (50 mL, 0.80 mmol) was added.
The mixture was stirred overnight at 40–458C in a closed
glass tube, cooled down to room temperature and
concentrated. The off-white solid so obtained was
separated by filtration and dried under vacuum (163 mg,
2
modified F was written on a new HKL file. The 275
o
electrons per unit cell thus located are included in the
formula, formula weight, calculated density, m and F(000).
This residual electron density was assigned to 12
molecules of acetonitrile per unit cell. All non-hydrogen
atoms were refined with anisotropic atomic displacements
with the exception of one acetonitrile molecule. The
hydrogen atoms were included in the refinement at
9
2%).
1
H NMR (200 MHz, CD OD): d (ppm) 3.97 (s, 6H,
3
CH ); 4.38 (s, 3H, CH ); 8.23 (m, 2H, CH meta to N); 8.80
2
3
(
m, 2H, CH ortho to N).
˚
idealised geometry (CZH 0.95A) and refined ‘riding’ on
the corresponding parent atoms.
The weighting schemes used in the last cycle of
4.6 Crystal structure determination of the Tiiii[C H ,
CH , Ph]·(C H INO )·5CH CN complex
3 7
3
10 16
3
3
2
2
2
refinement were w ¼ 1=½s F þ ð0:0848PÞ þ 1:4464Pꢀ,
o
The molecular structure of the inclusion compound
Tiiii[C H , CH , Ph]·(C H INO )·5CH CN was deter-
2
2
where P ¼ ðF þ 2F Þ=3. Molecular geometry calcu-
o
c
3
7
3
10 16
3
3
lations were carried out using the PARST97 program
26). Drawings were obtained using ORTEP3 in the
WinGX suite (27) and Mercury (28). Crystallographic data
excluding structure factors) for the structure reported
mined by single-crystal X-ray diffraction methods.
Crystallographic and experimental details are summarised
(
(
Table 2. Crystallographic data and refinement details for
compound Tiiii[C H , CH , Ph]z(C H INO )z5CH CN.
have been deposited with the Cambridge Crystallographic
Data Center as supplementary publication no. CCDC-
3
7
3
10 16
3
3
777331, and can be obtained free of charge on application
to the CCDC, 12 Union Road, Cambridge CB2 1EZ,
Tiiii[C H , CH , Ph]·
3
7
3
(
C
10
H
16INO
3
)·5CH
3
CN
UK. [Fax: þ44-1223/336-033; deposit@ccdc.cam.ac.uk].
Formula
C
88
H
1731.51
6 15 4
99IN O P
Formula weight
Crystal system
Space group
Monoclinic
P21/c
Acknowledgement
˚
a (A)
15.479 (3)
37.943 (6)
16.352 (3)
113.988 (2)
8775 (2)
4
1.311
3608
0.504
1.07, 28.56
71,985
We thank the German–Italian exchange Program (Vigoni
Program) for financial support.
˚
b (A)
˚
c (A)
b (8)
3
˚
V (A )
Z
D (g cm
References
2
3
)
c
(
1) Dutasta, J.-P. Top. Curr. Chem. 2004, 232, 55–91.
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1
31, 7447–7455.
19711 (Rint ¼ 0.0384)
(
(
(
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R
R
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¼ 0.0484, wR
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¼ 0.1296
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¼ 0.075, wR
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¼ 0.1420
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˚
/e A
Dr
S
21.097, 0.827
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R1 ¼ SkFoj 2 jFck=SjFoj, wR2 ¼ ½SwðF 2 F Þ =SwF ꢀ1=2.
2
o
2
c
2
4
o
b
2
2
c
2
1=2
Goodness-of-fit S ¼ ½SwðF 2 F Þ =ðn 2 pÞꢀ , where n is the number
o
of reflections and p is the number of parameters.
9325–9328.

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(
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999.
(
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(
(
(
(
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(
(
17) The crystal structure of TSiiii[C
acetonitrile included in the cavity has been determined
S. Geremia, M. Melegari, E. Dalcanale. unpublished results).
3 7 3
H , H, Ph]·CH CN with
1
(