Inhibiting copper(i) iodide aggregate assembly in the solid state via macrocyclic encapsulation

Article abstract of DOI:10.1039/c1dt10815h

Three CuI complexes of diimine-bearing macrocyclic ligands are described. Reaction of CuI with macrocycles of different ring size gives rise to differing degrees of aggregation of (CuI)_n in the solid state. X-Ray diffraction studies reveal that

Full text of DOI:10.1039/c1dt10815h

View Article Online / Journal Homepage / Table of Contents for this issue
This article is published as part of the Dalton Transactions themed issue entitled:
Self-Assembly in Inorganic Chemistry
Guest Editors Paul Kruger and Thorri Gunnlaugsson
Published in issue 45, 2011 of Dalton Transactions
Image reproduced with permission of Mark Ogden
Articles in the issue include:
PERSPECTIVE:
Metal ion directed self-assembly of sensors for ions, molecules and biomolecules
Jim A. Thomas
Dalton Trans., 2011, DOI: 10.1039/C1DT10876J
ARTICLES:
Self-assembly between dicarboxylate ions and a binuclear europium complex: formation of stable
adducts and heterometallic lanthanide complexes
James A. Tilney, Thomas Just Sørensen, Benjamin P. Burton-Pye and Stephen Faulkner
Dalton Trans., 2011, DOI: 10.1039/C1DT11103E
Structural and metallo selectivity in the assembly of [2 × 2] grid-type metallosupramolecular
species: Mechanisms and kinetic control
Artur R. Stefankiewicz, Jack Harrowfield, Augustin Madalan, Kari Rissanen, Alexandre N. Sobolev
and Jean-Marie Lehn
Dalton Trans., 2011, DOI: 10.1039/C1DT11226K
Visit the Dalton Transactions website for more cutting-edge inorganic and organometallic research
www.rsc.org/dalton

Dynamic Article Links
Dalton
Transactions
Cite this: Dalton Trans., 2011, 40, 12257
www.rsc.org/dalton
PAPER
Inhibiting copper(I) iodide aggregate assembly in the solid state via
macrocyclic encapsulation†
David J. Smith, Alexander J. Blake, Claire Wilson and Neil R. Champness*
Received 2nd May 2011, Accepted 2nd August 2011
DOI: 10.1039/c1dt10815h
Three CuI complexes of diimine-bearing macrocyclic ligands are described. Reaction of CuI with
macrocycles of different ring size gives rise to differing degrees of aggregation of (CuI)n in the solid
state. X-Ray diffraction studies reveal that whereas macrocycles with smaller ring sizes give rise to
simple mononuclear CuI diimine complexes, a macrocycle of larger ring size affords a dinuclear (CuI)2
moiety, encompassed within the ligand ring. Thus, the macrocycle can be seen to determine the extent
of CuI aggregation in the solid state.
oligomerisation determined by the incorporation of the (CuI)n
fragment within a macrocyclic cavity. We have utilised three macro-
cyclic ligands that contain diimine chelating ligands, either 1,10-
phenanthroline (L1, L2) or 2,2¢-bipyridine (L3) moieties. The size
of the macrocyclic ring varies, from the relatively small 24- or 22-
membered rings of L1 or L2, respectively, to the significantly larger
37-membered ligand L3 (Scheme 1). It was envisaged that the larger
macrocyclic cavity formed by L3 would allow the formation of
larger self-assembled oligomeric copper(I) iodide motifs following
coordination of the copper cation to the diimine ligand.
Introduction
Ligands capable of acting as bridges between metal centres can
be exploited to form self-assembled arrays in which ligand design
can be used in an attempt to control the resulting framework
structure.1,2 This strategy has been particularly successful in using
organic ligands, including bridging multi-dentate pyridine and
carboxylate systems, to prepare discrete cage structures1 as well
as coordination polymers and metal–organic frameworks.2
In contrast to organic bridging ligands that can be highly
designed to control geometry and coordination preferences, simple
inorganic ligands can be much harder to control in part because
they cannot be modified. Examples of such ligands include the
halide anions3 and pseudohalides such as thiocyanate.4 Over many
years, therefore, a range of systems has been studied in which
halides and pseudohalides adopt a large range of coordination
2
3
modes including h and h bridging modes, which can lead to
entirely different oligomeric and polymeric arrays of metal cations,
notably in the solid state.
One subset of such oligomeric structures comprises of those
formed by copper(I) halides (CuX)n (X = Cl, Br, I).3,5–8 In particular,
copper(I) iodide has been shown to form a range of oligomeric
species in the solid state through iodide bridging of copper(I)
cations: these include rhomboid dimers,5,6 cubane tetramers,5
and step tetramers,7 as well as a large variety of polymeric
arrays, ranging from simple chains6 and tubes8 to two-dimensional
sheets.6 Such structures have been shown to have interesting
photophysical properties9 but are extremely difficult to predict
and even more difficult to control.
Scheme 1 Macrocycles used in this study.
Results and discussion
Macrocycles L1 and L2 were prepared starting from the commer-
cially available 2,9-dimethyl-1,10-phenanthroline (neocuproine)
following previously described synthetic strategies.10,11 Thus, the
methyl substituents of neocuproine were readily functionalised
to the corresponding dialdehyde via oxidation with selenium(IV)
oxide,11 further oxidised to the dicarboxylic acid with concentrated
nitric acid and reacted on to form the more reactive acid chloride
using thionyl chloride.12 Reaction with either pentaethylene glycol
(L1) or 4,9-dioxadodecane-1,12-diamine (L2) using a Skraup-
type cyclisation10 gave the target macrocycles in reasonable yield
In this study we demonstrate that polymeric (CuI)n arrays and
larger oligomeric systems can be inhibited and the extent of
School of Chemistry, University of Nottingham, University Park, Not-
tingham, UK, NG7 2RD. E-mail: Neil.Champness@nottingham.ac.uk;
Fax: +44 115 951 3563; Tel: +44 115 951 3505
† CCDC reference numbers 824395–824397. For crystallographic data in
CIF or other electronic format, see DOI: 10.1039/c1dt10815h
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 12257–12264 | 12257
©

◦
˚
Table 1 Selected bond lengths (A) and bond angles ( ) in compounds 1,
2 and 3
(Scheme 2). The pre-organisation of the functional groups of
1,10-phenanthroline-2,9-dicarbonyl chloride allows cyclisation to
proceed in respectable yield without need of a template.
1
2
Cu1–I1
Cu1–N1
2.5888(6)
2.155(3)
2.121(3)
Cu1–I1
Cu1–N1
Cu1–N10
Cu1–N1A
I1–Cu1–N1
I1–Cu1–N1A
I1–Cu1–N10
N1–Cu1–N1A
N1–Cu1–N10
N1A–Cu1–N10
2.6274(3)
2.0941(14)
2.0703(14)
1.9320(16)
102.57(4)
115.24(5)
106.36(4)
122.78(6)
81.91(5)
Cu1–N10
Cu1–N1A
I1–Cu1–N1
I1–Cu1–N1A
I1–Cu1–N10
N1–Cu1–N1A
N1–Cu1–N10
N1A–Cu1–N10
3
Cu1–I1
Cu1–I2
Cu1–N11
Cu1–N21
Cu2–I1
1.949(4)
108.20(9)
114.95(9)
104.52(10)
122.37(14)
79.29(11)
121.67(12)
122.31(6)
2.6352(11)
2.6577(11)
2.122(5)
I1–Cu1–I2
114.37(3)
102.76(14)
122.11(13)
126.04(13)
107.88(14)
80.9(2)
I1–Cu1–N11
I1–Cu1–N21
I2–Cu1–N11
I2–Cu1–N21
N11–Cu1–N21
I1–Cu2–I2
2.124(5)
2.5483(12)
2.5165(12)
1.956(6)
109.8(2)
127.0(2)
Cu2–I2
Cu2–N1A
I1–Cu2–N1A
I2–Cu2–N1A
122.86(3)
Scheme 2 Synthetic route to macrocycles L1 and L2.
of MeCN in the crystal lattice remains uncoordinated. The
coordination geometry is considerably distorted from a uniform
tetrahedron with bond angles around the copper centre ranging
from 79.29◦ to 122.37◦ (Table 1) with the smallest of these,
unsurprisingly, being the bite angle of the phenanthroline nitrogen
atoms. The flexible glycol linker of L1 curves away from the iodide
anion but space-filling models show that the CuI(MeCN) moiety
is predominantly encapsulated within the macrocyclic framework
(Fig. 1b).
Macrocycle L3 was prepared by a synthetic route slightly
modified from that originally described by Collin, Sauvage et al.13
(Scheme 3). Thus 2-bromo-6-(4-anisyl)pyridine was prepared in
45% yield by coupling 2,6-dibromopyridine with 4-bromoanisole
using Negishi conditions.14 Homo-coupling of 2-bromo-6-
(4-anisyl)pyridine using a heteroaryllithium coupling reaction
with thionyl chloride gave 6,6¢-di-(4-anisyl)-2,2¢-bipyridine in 47%
yield.15 Anisyl groups were then quantitatively deprotected by
refluxing 6,6¢-di-(4-anisyl)-2,2¢-bipyridine in pyridine hydrochlo-
ride to afford 6,6¢-di-(4-hydroxyphenyl)-2,2¢-bipyridine using the
previously described procedure.16 The other half of the target
macrocycle L3 was prepared using minor modifications of the pre-
viously described route.13 Thus 2,2¢-(bis-4-hydroxyphenyl)propane
was treated with 2-(2-chloroethoxy)ethanol to afford the target
diol. The pendant alcohol groups were converted to the corre-
sponding diiodide, via the tosylate, giving a molecule suitable
for cyclisation in combination with 6,6¢-di-(4-hydroxyphenyl)-2,2¢-
bipyridine, using caesium carbonate as a base, to afford L3 in 29%
yield.
Complex 2, Cu(L2)I(CH3CN), crystallises in the triclinic space
¯
group P1 as bright yellow tablets. A single-crystal X-ray diffrac-
tion experiment demonstrates that the copper(I) cation in 2 adopts
a similar arrangement and an analogous pseudo-tetrahedral
N2I(NCMe) coordination environment to that observed in 1
(Fig. 2a, Table 1). As in 1, the copper(I) cation in 2 displays
considerable distortion from a uniform tetrahedral coordination
geometry with bond angles ranging from 81.91◦, the geometrically
constrained bite angle of the chelating ligand, to 122.78◦ (Table 1).
In this instance the macrocycle, L2, adopts a relatively flat
conformation accommodating the CuI(NCMe) group within
the macrocyclic fragment (Fig. 2b). The conformation of the
macrocycle is affected by adoption of intramolecular hydrogen-
bonding interactions between the N–H groups of the macrocycle
backbone and the coordinated iodide anion (N17–H◦17 ◊ ◊ ◊ I1:
Copper(I) iodide coordination chemistry
Compounds 1–3 were prepared using analogous methods by react-
ing a slight excess of copper(I) iodide with the appropriate macro-
cycle L1 (1), L2 (2) or L3 (3) in acetonitrile solution. Slow diffusion
of diethyl ether into the resulting reaction solution gave crystals of
the products [Cu(L1)I(CH3CN)]·CH3CN 1, Cu(L2)I(CH3CN) 2,
or [Cu2(L3)(m-I)2(CH3CN)]·CH3CN 3, suitable for single crystal
X-ray diffraction studies and investigation of the solid state
structures.
Complex 1, [Cu(L1)I(CH3CN)]·CH3CN, crystallises as dark red
rods in the monoclinic space group P21/c. Refinement of the
structure reveals the copper(I) sitting in a pseudo-tetrahedral
coordination geometry (Fig. 1a, Table 1). The macrocyclic ligand
L1 coordinates to copper(I) via both phenanthroline nitrogen
atoms, an iodide anion and one MeCN ligand. A second molecule
˚
N ◊ ◊ ◊ I = 3.848(2); H ◊ ◊ ◊ I = 2.97 A; <N–H–I = 176 ; N20–
◦
˚
H20 ◊ ◊ ◊ I1: N ◊ ◊ ◊ I = 3.719(2); H ◊ ◊ ◊ I = 2.89 A; <N–H–I = 158 )
(Fig. 2c). In 1 and 2 the Cu(I) coordination spheres and bond
lengths are in agreement with related CuI compounds combined
with 1,10-phenanthroline based ligands.17
Complex 3, [Cu2(L3)(m-I)2(CH3CN)]·CH3CN, was prepared in
a similar manner to 1 and 2. 3 crystallises in the orthorhombic
space group P212121 as orange sphenoids. Structural refinement
revealed that 3 adopts a 1 : 2 ligand : metal ratio (Fig. 3, Table 1)
in which a copper(I) iodide dimer is formed. One pseudo-
tetrahedral copper(I) cation, Cu1, is coordinated by L3 through the
chelating phenanthroline donor with the remaining coordination
sites occupied by two iodide anions. The iodide anions bridge the
12258 | Dalton Trans., 2011, 40, 12257–12264
This journal is
The Royal Society of Chemistry 2011
©

Scheme 3 Synthetic pathway to L3.
19
˚
two copper centres, Cu1 and Cu2, to form the dimeric arrange-
ment, with Cu2 adopting a pseudo-trigonal planar geometry and
completing its coordination sphere with an MeCN ligand. CuI is
known to form a range of oligomeric species, but it can be seen
from the space filling diagram of the structure of 3 (Fig. 3b) that
the dimeric arrangement fits well within the macrocyclic cavity. It
is postulated that the cavity size of L3 allows the formation of the
dimeric (CuI)2 moiety but inhibits the formation of higher copper
iodide oligomers in this instance.
(2.03–2.11 A). Bond angles around the pseudo-tetrahedral Cu1
range from 80.9(2)◦, due to 2,2¢-bipyridine coordination, to
126.04(13)◦. Cu2–iodide bond lengths are considerably shorter
than Cu1–I bond lengths (Table 1), consistent with structural data
for three-coordinate copper(I) cations in copper iodide dimers.18
Cu2 has a slightly distorted trigonal planar coordination geometry
˚
(mean deviation from least-squares plane 0.0331 A), with bond
angles ranging between 109.8(2)◦ and 127.0(2)◦ (Table 1). The
iodide bridging arrangement results in a copper–copper separation
˚
The Cu–I bond lengths observed for Cu1 in 3 (Table 1) are
comparable with those reported for various copper(I) iodide
structures involving pyridine ligands.6,18 Similarly, the Cu–Npy
bond lengths in 3 are comparable to those observed for related
bis-(2,9-diphenyl-1,10-phenanthroline)–copper(I) cation systems
of 2.56 A, which is identical to the internuclear distance in metallic
copper and consistent with Cu ◊ ◊ ◊ Cu separations observed in other
(CuI)2 dimers with nitrogen-based ligands.6,18
The solid state structures were investigated further to probe
whether additional intermolecular interactions in the solid state
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 12257–12264 | 12259
©

Fig. 1 Views of the single crystal structure of 1: (a) as a displacement ellipsoid plot drawn at the 50% probability level; (b) the corresponding space-filling
model: nitrogen – blue, iodine – purple, oxygen – red, carbon – grey. The uncoordinated MeCN solvent molecule has been omitted from both parts of the
figure for clarity.
may stabilise the observed CuI motifs. Complexes 1 and 2 exhibit
favourable p–p stacking interactions between phenanthroline
moieties of adjacent molecules centroid ◊ ◊ ◊ centroid separations of
indicating that the aforementioned (CuI)2 dimer is unstable in
solution.
˚
˚
˚
˚
3.53 A (1) or 3.89 A (2) and an offset of 0.95 A (1) or 1.76 A (2) with
the formation of dimeric assemblies in the solid state. Complex 3
also adopts p–p stacking interactions, in this case between adjacent
2,2¢-bipyridyl groups, with centroid ◊ ◊ ◊ centroid separations of 3.86
Conclusion
In conclusion we have synthesised and characterised copper(I)
iodide complexes of three macrocyclic ligands incorporating
diimine ligands. Single-crystal X-ray diffraction studies revealed
that the two smaller macrocycles L1 and L2 both formed 1 : 1
complexes with CuI in which the copper(I) cation is tetrahedrally
coordinated by the chelating phenanthroline, an iodide anion and
an MeCN ligand. Conversely, compound 3 forms a (CuI)2 dimer
in which the larger macrocycle allows the aggregation of this larger
copper(I) iodide assembly. Hirshfeld surface analysis of the three
structures confirms that there are no significant intermolecular
interactions associated with the iodide anions and therefore
the degree of CuI aggregation in the solid state is determined
primarily by the macrocycle cavity size. Thus, for systems in
which aggregation of larger oligomeric inorganic systems, such
as copper(I) iodide, the use of a macrocyclic ligand system with
controllable cavity size is a realistic method of limiting the degree
of aggregation in the solid state.
˚
˚
or 4.09 A and offset of 1.09 or 1.76 A leading to the formation of
extended stacks of complexes (Fig. 4).
Hirshfeld surface analysis20 of the structures of 1–3 was used to
explore further intermolecular interactions in the three structures
(Fig. 5). In particular we were interested to evaluate interactions
with the iodide anions to assess whether the observed structures
were purely a solid state phenomenon arising from strong and
specific intermolecular interactions stabilising particular (CuI)n
arrangements. It is notable that the Hirshfeld surface analysis
does not reveal significant interactions between the iodide ligands
and other groups, and indicates that interactions such as halogen
bonding21 are not significant in the observed structures. In the case
of 1 an interaction is observed in the Hirshfeld surface analysis
between the iodide ligand and a MeCN solvent molecule (C ◊ ◊ ◊ I =
˚
˚
4.04 A, H ◊ ◊ ◊ I = 3.18 A), however this is unlikely to be a particularly
strong hydrogen bonding interaction.22 No significant interactions
associated with the iodide anions are revealed by the Hirshfeld
surface analysis of 2 and 3. Thus it can be concluded that the solid
state structures of the (CuI)n moieties in 1–3 are not significantly
affected by intermolecular interactions. This indicates that the
degree of CuI aggregation is influenced predominantly by the
nature of the macrocyclic ring size.
Experimental
All reagents and solvents were purchased from Sigma Aldrich,
Alfa Aesar or Fisher Scientific UK, and used without further
purification unless otherwise stated. 1,10-Phenanthroline-2,9-
dicarbonyl chloride12 was prepared from 1,10-phenanthroline-
2,9-dialdehyde11 using literature methods. In cases where ligand
precursors have been previously13 reported we have not included
complete characterisation data here. Elemental microanalyses
were carried out by Stephen Boyer at the Microanalysis Service,
London Metropolitan University, UK. Infrared spectra were
measured as pure solids using a Nicolet Avatar 320 ATR FT-
IR spectrometer over the range 400–4000 cm-1. 1H and 13C NMR
spectra were measured using a Jeol 270 MHz spectrometer. Mass
In solution, the three complexes exhibit quite different be-
haviour. Electrospray ionisation mass spectrometry of 1 is con-
sistent with retention of the CuI(L1) fragment, the peak at 771.25
corresponding to [(L1)CuI/NH4]+. Corresponding mass spectra
for 2 indicated that the complex does not remain intact, with
loss of iodide from the copper coordination sphere. The mass
spectrum of 3 also displayed no peaks consistent with the solid
state structure, with a peak at 771.25 consistent with [(L3)63Cu]+,
12260 | Dalton Trans., 2011, 40, 12257–12264
This journal is
The Royal Society of Chemistry 2011
©

Fig. 3 Views of the single crystal structure of 3: (a) as a displacement
ellipsoid plot drawn at the 50% probability level; (b) the corresponding
space-filling model: nitrogen – blue, iodine – purple, copper – orange,
oxygen – red, carbon – grey. The uncoordinated MeCN solvent molecule
has been omitted from both parts of the figure for clarity.
Fig. 2 Views of the single crystal structure of 2: (a) as a displacement
ellipsoid plot drawn at the 50% probability level; (b) the corresponding
space-filling model and (c) intramolecular N–H ◊ ◊ ◊ I hydrogen bonds
between the macrocycle amide units and the iodide ligand: nitrogen –
blue, iodine – purple, oxygen – red, carbon – grey, hydrogen bond shown
in light blue. The uncoordinated MeCN solvent molecule has been omitted
from the figures for clarity.
spectrometry measurements were performed by the University of
Nottingham Mass Spectrometry Service using a Micromass LCT
instrument (ES-MS) or a VG Autospec instrument (FAB-MS).
Synthesis of L1
Under an inert atmosphere, to a refluxing solution of 1,10-
phenanthroline-2,9-dicarbonyl chloride12 (0.5 g, 1.64 mmol) in
dry, degassed toluene (1000 mL) was added, dropwise during 2 h,
a solution of pentaethylene glycol (0.34 g, 0.3 mL, 1.42 mmol) in
dry toluene (250 mL). Heating was continued for 5 h. The solution
was allowed to cool and filtered and the filtrate concentrated in
vacuo. The residue was recrystallised from hot MeOH to afford
L1 as a white solid (0.41 g, 0.87 mmol, 61%). 1H NMR [CDCl3]:
d 8.52–8.49 (d, 2H, H3 and H8), 8.45–8.42 (d, 2H, H4 and H7),
7.96 (s, 2H, H5 and H6), 4.73–4.69 (m, 4H), 4.11–4.07 (m, 4H),
3.89–3.84 (m, 4H), 3.76–3.71 (m, 4H); 13C NMR [CDCl3]: d 166.0,
148.1, 137.8, 130.8, 128.4, 124.1, 100.0, 71.1, 70.9, 69.3, 65.5; Anal.
Calc’d for C22H22N2O7: C 61.97, H 5.20, N 6.57; found: C 61.65, H
Fig. 4 View of the single crystal structure of 3 demonstrating the
p–p stacking interactions observed between adjacent 2,2¢-bipyridyl units
leading to the formation of extended arrays: nitrogen – blue, iodine –
purple, copper – orange, oxygen – red, carbon – grey. The uncoordinated
MeCN solvent molecule has been omitted from the figure for clarity.
5.29, N 6.71; I.R. (ATR): 3559w, 3507w, 2968m (br), 2900m (br),
1724s, 1710s, 1637w, 1437w, 1369m, 1347m, 1301m, 1276s, 1161s,
1121s, 1096s, 1082s, 1026m, 950m, 874m, 815w, 720s.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 12257–12264 | 12261
©

2340s (br), 1719s, 1359m, 1323m, 1256w, 1158w, 1107s, 1085m,
961m, 880w, 715m.
Synthesis of 2
Complex 2 was prepared in an identical manner to 1 with L2
replacing L1 in the synthetic procedure. FAB-MS: m/z 499.1, 501.2
((M-I-CH3CN)+); Anal. Calc’d for C26H31CuIN5O4: C 46.75, H
4.68, N 10.48; found: C 46.71, H 4.65, N 10.39; I.R. (ATR): 3676w,
3660w, 3278w, 2989s, 2972s (br), 2901s (br), 2366w, 1671m, 1656s,
1539m, 1498m, 1407w, 1394w, 1312w, 1242m, 1162m, 1085s, 1066s,
1047s, 886m, 808m.
Synthesis of 2-bromo-6-(4-methoxyphenyl)pyridine
◦
n
At -78 C under an inert atmosphere, BuLi (2.5 M solution in
hexanes, 12.0 mL, 29.55 mmol) was added dropwise to a stirred
solution of 4-bromoanisole (5.52 g, 3.70 mL, 29.51 mmol) in
dry THF (100 mL). A solution of ZnCl2 (4.03 g, 29.55 mmol)
in dry THF (100 mL) was cooled to 0 ◦C and added to the
resultant 4-lithioanisole solution and the mixture allowed to
warm to room temperature. A solution of 2,6-dibromopyridine
(7.0 g, 29.55 mmol) and tetrakis(triphenylphosphine) palladium(0)
(1.75 g, 1.51 mmol) in dry THF (50 mL) was added dropwise
to the reaction mixture, which was subsequently heated at reflux
for 20 h, allowed to cool and the solvent removed in vacuo. The
crude mixture was taken up in CH2Cl2 (200 mL) and washed with
two portions of a saturated aqueous solution of ethylenediamine
tetraacetic acid (disodium salt) (200 mL) and one portion of 5 M
aqueous sodium hydroxide solution (200 mL). The organic phase
was retained and the solvent removed in vacuo. The crude product
was purified by column chromatography on silica (eluent 1% ethyl
acetate in hexane) to yield the product as a white solid (3.41 g,
12.91 mmol, 44%). 1H NMR [CDCl3]: d 7.97–7.93 (d, 2H), 7.64–
Fig. 5 Hirshfeld surface analysis of (a) 1, (b) 2, (c) 3. Areas shown in red
indicate interactions with adjacent molecules. It is notable that the iodide
anions do not participate in significant intermolecular interactions.
Synthesis of L2
Under an inert atmosphere, to a room temperature solution of
1,10-phenanthroline-2,9-dicarbonyl chloride12 (0.5 g, 1.64 mmol)
in dry, degassed THF (1000 mL) was added, dropwise during 3 h,
a solution of 4,9-dioxadodecane-1,12-diamine (0.38 g, 0.4 mL,
1.85 mmol) and NEt3 (2.1 eq., 0.39 g, 0.5 mL, 3.89 mmol) in
dry THF (200 mL) and subsequently stirred at room temperature
for 48 h. Solvent was removed in vacuo and the residue taken
up in CHCl3 (100 mL) and washed with 3 portions of water
(100 mL). The organic phase was dried over MgSO4 and the
solvent removed in vacuo. The crude product was purified by
column chromatography on silica (eluent 3% MeOH in CH2Cl2)
to afford L2 as a white solid (0.40 g, 0.92 mmol, 56%). 1H NMR
[CDCl3]: d 9.05–9.00 (m, 2H, NH), 8.62–8.58 (d, 2H, H3 and H8),
8.44–8.41 (d, 2H, H4 and H7), 7.90 (s, 2H, H5 and H6), 3.74–3.50
(m, 12H); 13C NMR [CDCl3]: d 164.8, 150.5, 144.4, 138.0, 130.7,
127.9, 122.0, 70.5, 67.6, 37.0, 29.2, 26.6; ESI-MS: m/z 437 (MH+),
459 (MNa+), 895 (2MNa+); Anal. Calc’d for C24H28N4O4: C 66.04,
H 6.47, N 12.84; found: C 65.84, H 6.50, N 12.83; I.R. (ATR):
3484w (br), 3423w, 2946m (br), 2856m (br), 1675s, 1545s, 1500s,
1400w, 1377w, 1291w, 1266w, 1175m, 1124m, 1105s, 1081s, 1053m,
1016w, 872s, 717s.
7.50 (m, 2H), 7.30–7.38 (d, 1H), 7.00–6.96 (d, 2H), 3.87 (s, 3H); 13
C
NMR [CDCl3]: d 161.6, 158.1, 142.0, 139.0, 130.3, 128.4, 125.5,
118.2, 114.2, 55.5, 42.8, 30.0; ESI-MS: m/z 264.0, 266.0 (MH+)
Anal. Calc’d for C12H10BrNO: C 54.57, H 3.82, N 5.30; found: C
54.59, H 3.90, N 5.33.
Synthesis of 6,6¢-di-(4-hydroxyphenyl)-2,2¢-bipyridine
◦
n
At -78 C under an inert atmosphere, BuLi (2.5 M solution in
hexanes, 3.0 mL, 7.6 mmol) was added dropwise to a stirred so-
lution of 2-bromo-6-(4-methoxyphenyl)pyridine (2.0 g, 7.6 mmol)
in dry diethyl ether (40 mL) and the mixture stirred for 1 h. A
solution of thionyl chloride (0.3 g, 0.2 mL, 2.52 mmol) in dry
diethyl ether (30 mL) was added dropwise and the beige-coloured
solution stirred for 1.5 h, allowed to warm to room temperature
and treated with water (10 mL). The organic phase was separated
and washed with water (30 mL) and the solvent removed in vacuo
to give the crude product as a pale brown solid. The product
was purified by column chromatography on silica (eluent 5% ethyl
acetate in hexane) to afford the product as a white solid (0.66 g,
Synthesis of 1
L1 (0.02 g, 0.04 mmol) and CuI (0.01 g, 0.05 mmol) were dissolved
in dry MeCN (10 mL) and the mixture heated at reflux for 10 min.
After cooling, undissolved material was removed by filtration.
The resultant saturated solution (0.5 mL) was diluted with dry
MeCN (0.5 mL) and the complex 1 crystallised by slow diffusion
of diethyl ether. FAB-MS: m/z 533.2, 535.3 (M-I-CH3CN)+), 678.2
((M+NH4-CH3CN)+), 683.1, 685.1 ((M+Na-CH3CN)+); Anal.
Calc’d for C28H32CuIN4O8: C 45.26, H 4.34, N 7.54; found: C
45.16, H 4.23, N 7.39; I.R. (ATR): 3853w, 3629w, 2360s (br),
1
1.79 mmol, 47%). H NMR [CDCl3]: d 8.57–8.53 (d, 2H), 8.16–
8.12 (d, 4H), 7.94–7.84 (t, 2H), 7.74–7.69 (d, 2H), 7.07–7.03 (d,
4H), 3.90 (s, 6H); ESI-MS: m/z 369.2 (MH+).
Synthesis of 2,2¢-(bis-4-phenoxyethoxy-ethanol)propane
Under an inert atmosphere, a solution of 2,2-bis(4-hydroxy-
phenyl)propane (5.0 g, 21.9 mmol), K2CO3 (~6 g, excess) and
12262 | Dalton Trans., 2011, 40, 12257–12264
This journal is
The Royal Society of Chemistry 2011
©

a catalytic amount of 18-crown-6 (0.1 g, 0.34 mmol) in dry
MeCN (100 mL) was heated to reflux for 1 h. A solution of
2-(2-chloroethoxy)ethanol (6.83 g, 5.8 mL, 54.75 mmol) in dry
MeCN (100 mL) was added dropwise with stirring to the refluxing
reaction mixture. Heating and stirring were continued for 72 h.
The solvent was removed in vacuo and the residue taken up in
CHCl3 (200 mL) and washed with water (2 ¥ 200 mL). The
organic phase was retained, dried over MgSO4 and the solvent
removed in vacuo. The crude oily residue was purified by column
chromatography on silica (gradient elution 1% up to 3% MeOH
in CH2Cl2) affording 2,2¢-(bis-4-phenoxyethoxy-ethanol)propane
caesium carbonate (1.89 g, 5.8 mmol) in DMF (500 mL) stirred
at 60 ◦C. At the end of the addition, stirring and heating were
continued for 48 h. DMF was removed in vacuo and the residue
taken up in a 1 : 1 mixture of water and CH2Cl2 (500 mL). The
aqueous layer was extracted with CH2Cl2 (3 ¥ 150 mL). The
organic fractions were combined and the solvent removed in vacuo.
The crude brown residue was purified by column chromatography
on silica (eluent CH2Cl2), affording L3 as an off-white solid (0.38
1
g, 0.54 mmol, 29.2%). H NMR [CDCl3]: d 8.18–8.15 (d, 4H),
7.85–7.71 (m, 6H), 7.10–7.03 (dd, 8H) 6.78–6.74 (d, 4H), 4.27–
4.22 (m, 4H), 4.09–4.03 (m, 4H), 3.96–3.90 (m, 4H), 3.88–3.83
(m, 4H), 1.61 (s, 6H); 13C NMR [CDCl3]: d 160.4, 156.6, 156.1,
143.2, 137.7, 132.0, 128.4, 127.6, 119.9, 119.1, 115.3, 114.2, 70.1,
69.8, 67.7, 41.9, 30.9, 29.7; ESI-MS: m/z 709.3 (MH+); I.R. (ATR):
2923m (br), 2852m (br), 1732w (br), 1606m, 1563m, 1509s, 1435m,
1305w, 1251s, 1182s, 1127m (br), 1065s, 946w, 834m, 797s.
1
as a colourless oil (4.7 g, 11.5 mmol, 53%). H NMR [CDCl3]:
d 7.14–7.10 (d, 4H), 6.83–6.79 (d, 4H), 4.13–4.09 (m, 4H), 3.86–
3.81 (m, 4H), 3.78–3.73 (m, 4H), 3.70–3.64 (m, 4H), 1.62 (s, 6H);
ESI-MS: 405.2 (MH+), 422.3 (M(NH4)+), 427.2 (MNa+).
Synthesis of 2,2¢-(bis-4-phenoxydiethoxy-p-tosylate)propane
Synthesis of 3
Under an inert atmosphere,
a
solution of 2,2¢-(bis-4-
phenoxyethoxy-ethanol)propane (4.7 g, 11.5 mmol), triethy-
lamine (6.9 mL, 68.3 mmol) and a catalytic amount of 4-
(dimethylamino)pyridine (DMAP) in dry CH2Cl2 (150 mL) was
cooled with stirring to 0 ◦C. A solution of 4-toluenesulfonyl
chloride (6.5 g, 34.3 mmol) in dry CH2Cl2 (150 mL) was added
dropwise over 1.5 h and the mixture stirred at 0 ◦C for 3 h before
warming to room temperature. The reaction mixture was washed
with water (2 ¥ 300 mL), dried over MgSO4 and the solvent
removed in vacuo. The crude residue was purified by column
chromatography on silica (eluent CH2Cl2) to afford 2,2¢-(bis-4-
phenoxydiethoxy-p-tosylate)propane as a pale yellow solid (5.16
g, 7.23 mmol, 63%). 1H NMR [CDCl3]: d 7.82–7.78 (d, 4H), 7.31–
7.27 (d, 4H), 7.16–7.11 (d, 4H), 6.80–6.76 (d, 4H), 4.20–4.17 (m,
4H), 4.04–3.99 (m, 4H), 3.79–3.72 (m, 8H), 2.41 (s, 6H), 1.64 (s,
6H); ESI-MS: m/z 730.3 (M(NH4)+); Anal. Calc’d for C37H44O10S2:
C 62.34, H 6.22, N 0.00; found: C 62.32, H 6.25, N 0.00.
L3 (0.02 g, 0.03 mmol) and CuI (0.01 g, 0.05 mmol) were dissolved
in dry MeCN (10 mL) and the mixture heated at reflux for 10 min.
After cooling, undissolved material was removed by filtration. The
resultant saturated solution (0.5 mL) was diluted with dry MeCN
(0.5 mL) and the complex [Cu2(L3)(m-I)2(CH3CN)]·CH3CN, 3,
crystallised by slow diffusion of diethyl ether. FAB-MS: m/z 771.2,
773.3 ((M-Cu)+); Anal. Calc’d for C47H47Cu2I2N3O6: C 49.92, H
4.19, N 3.72; found: C 49.82, H 4.08, N 3.68; I.R. (ATR): 1607w,
1514w, 1448w, 1305m, 1233s, 1178m, 1124s, 982m, 793m, 749w.
Crystallography
All single-crystal X-ray experiments were performed either on
a Bruker SMART1000 CCD or a Bruker SMART APEX
CCD equipped with an Oxford Cryosystems open flow cryostat,
˚
[graphite monochromated Mo-Ka radiation (l = 0.71073 A);
w scans]. Absorption corrections, if necessary, were applied by
a semi-empirical approach. All of the single crystal structures
were solved by direct methods using SHELXS97,23 and all
non-H atoms were located using subsequent difference-Fourier
methods.23 Methyl H atoms were located in difference Fourier
maps and thereafter refined as part of rigid rotating groups;
other H atoms were placed in calculated positions and allowed
to ride on their parent atoms. In the structure of 3, extensive
disorder was encountered in the 2,2¢-diphenoxypropyl region of
the macrocyclic ligand. The occupancies of the major and minor
disorder components refined to 0.576(7) and 0.424(7), respectively,
following the application of extensive similarity restraints to
the geometric parameters and of rigid-bond restraints to the
displacement parameters.
Synthesis of 2,2¢-(bis-4-phenoxydiethoxyiodide)propane
NaI (4.3 g, 28.92 mmol) was added with stirring to a so-
lution in acetone (125 mL) of 2,2¢-(bis-4-phenoxydiethoxy-p-
tosylate)propane (5.16 g, 7.23 mmol) and the mixture heated at
reflux for 2 h. After cooling to room temperature, the mixture was
filtered to remove sodium 4-toluenesulfonate, and concentrated
in vacuo. The pale yellow residue was dissolved in diethyl ether
(125 mL) and washed with water (125 mL). The aqueous phase
was washed twice with diethyl ether (75 mL). The combined
organic fractions were decolourised with 20% aqueous sodium
thiosulfate solution and the solvent removed in vacuo to afford 2,2¢-
(bis-4-phenoxydiethoxyiodide)propane as a colourless oil (4.14 g,
6.63 mmol, 91.7%). 1H NMR [CDCl3]: d 7.15–7.12 (d, 4H), 6.84–
6.80 (d, 4H), 4.14–4.10 (m, 4H), 3.88–3.80 (m, 8H), 3.31–3.26 (m,
4H), 1.64 (s, 6H); Anal. Calc’d for C23H20I2O4: C 44.25, H 4.84;
found: C 44.16, H 4.89.
Crystal data for 1: C26H29CuIN3O8·C2H3N. Monoclinic, space
group P21/c (No.◦14), a = 11.7823(9), b = 27.558(2), c = 9.8575(8)
3
˚
˚
A, b = 109.276(2) , V = 3021.3(7) A , T = 150(2) K, Z = 4, Dc =
1.633 g cm-3, m = 1.799 mm-1, F(000) = 1496. A total of 19 276
reflections were collected, of which 7080 were unique, with Rint
0.040. Final R1 (wR2) = 0.0469 (0.0956) with GOF = 1.05.
Crystal data for 2: C26H31CuIN5O4. Triclinic, space group P1
=
Synthesis of L3
¯
Under an inert atmosphere, 6,6¢-di-(4-hydroxyphenyl)-2,2¢-
bipyridine (0.63 g, 1.85 mmol) and 2,2¢-(bis-4-phenoxy-
diethoxyiodide)propane (1.25 g, 2.00 mmol) were dissolved in dry,
degassed DMF (100 mL) and added over 24 h to a suspension of
˚
˚
(No. 2), a = 9.4406(5), b = 11.3913(6), c = 12.9336(7) A, a =
◦
3
94.923(1), b = 96.118(1), g = 97.922(1) , V = 1362.6(2) A , T =
150(2) K, Z = 2, Dc = 1.623 g cm-3, m = 1.975 mm-1, F(000) = 672.
This journal is
The Royal Society of Chemistry 2011
Dalton Trans., 2011, 40, 12257–12264 | 12263
©

A total of 11 731 reflections were collected, of which 6202 were
unique, with Rint = 0.012. Final R1 (wR2) = 0.0217 (0.0566) with
GOF = 1.04.
5 A. J. Blake, N. R. Brooks, N. R. Champness, M. Crew, D. H. Gregory,
P. Hubberstey, M. Schro¨der, A. Deveson, D. Fenske and L. R. Hanton,
Chem. Commun., 2001, 1432–1433.
6 F. The´bault, S. A. Barnett, A. J. Blake, C. Wilson, N. R. Champness
Crystal data for 3: C47H47Cu2I2N3O6·C2H3N. Orthorhombic,
and M. Schroder, Inorg. Chem., 2006, 45, 6179–6187.
7 P. C. Healy, J. D. Kildea, B. W. Skelton and A. H. White, Aust. J. Chem.,
1989, 42, 79.
¨
space group P212121 (No. 19), a = 7.673(2), b = 18.734(4), c =
3
-3
˚
˚
35.572(7) A, V = 5113(3) A , T = 150(2) K, Z = 4, Dc = 1.522 g cm ,
m = 2.088 mm-1, F(000) = 2336. A total of 25 567 reflections were
collected, of which 10 188 were unique, with Rint = 0.038. Final
R1 (wR2) = 0.0435 (0.0994) with GOF = 1.03. Flack parameter =
0.01(2).
8 A. J. Blake, N. R. Brooks, N. R. Champness, P. A. Cooke, A. M.
Deveson, D. Fenske, P. Hubberstey, W.-S. Li and M. Schro¨der, J. Chem.
Soc., Dalton Trans., 1999, 2103–2110.
9 P. C. Ford, Coord. Chem. Rev., 1994, 132, 129–140.
10 C. O. Dietrich-Bu¨checker, P. A. Marnot and J.-P. Sauvage, Tetrahedron
Lett., 1982, 23, 5291; C. J. Chandler, L. W. Deady and J. A. Reiss, J.
Heterocycl. Chem., 1986, 23, 1327–1330.
11 C. J. Chandler, L. W. Deady and J. A. Reiss, J. Heterocycl. Chem., 1981,
18, 599.
Acknowledgements
12 C. J. Chandler, L. W. Deady, J. A. Reiss and V. Tzimos, J. Heterocycl.
Chem., 1982, 19, 1017.
13 J.-P. Collin, D. Jouvenot, M. Koizumi and J.-P. Sauvage, Inorg. Chem.,
2005, 44, 4693–4698.
14 A. O. King, N. Okukado and E. Negishi, J. Chem. Soc., Chem.
Commun., 1977, 683; A. P. Smith, S. A. Savage, J. C. Love and C.
L. Fraser, Organic Syntheses, 2004, 10, 517.
We would like to gratefully acknowledge the support of the
Engineering and Physical Sciences Research Council for funding.
N.R.C. gratefully acknowledges the receipt of a Royal Society
Leverhulme Trust Senior Research Fellowship.
15 Y. Uchida, N. Echikawa and S. Oae, Heteroat. Chem., 1994, 5, 409.
16 T. J. Curphey, E. J. Hoffman and C. McDonald, Chem. Ind., 1967,
1138.
References
1 M. D. Ward, Chem. Commun., 2009, 4487–4499.
17 Y.-J. Shi, S.-J. Chen, B. Huang, X.-T. Chen, Y. Zhang and X.-Z. You,
J. Mol. Struct., 2003, 650, 27; P. C. Healy, C. Pakawatchai and A. H.
White, J. Chem. Soc., Dalton Trans., 1985, 2531.
18 M. Munakata, T. Kuroda-Sowa, M. Maekawa, A. Honda and S.
Kitagawa, J. Chem. Soc., Dalton Trans., 1994, 2771.
19 B. Wu, P. Yang, X. Huang, Y. Liu, X. Liu and C. Xia, Z. Anorg.
Allg. Chem., 2006, 632, 684–688; M. T. Miller, P. K. Gantzel and T. B.
Karpishin, Inorg. Chem., 1998, 37, 2285–2290.
2 N. R. Champness, Dalton Trans., 2006, 877–880; B. F. Hoskins and
R. Robson, J. Am. Chem. Soc., 1990, 112, 1546; M. Eddaoudi, D. B.
Moler, H. L. Li, B. L. Chen, T. M. Reineke, M. O’Keeffe and O. M.
Yaghi, Acc. Chem. Res., 2001, 34, 319; A. J. Blake, N. R. Champness, T.
L. Easun, D. R. Allan, H. Nowell, M. W. George, J. Jia and X.-Z. Sun,
Nat. Chem., 2010, 2, 688–694; S. Kitagawa and K. Uemura, Chem. Soc.
Rev., 2005, 34, 109–119; T. Uemura, N. Yanai and S. Kitagawa, Chem.
Soc. Rev., 2009, 38, 1228–1236.
20 M. A. Spackman and D. Jayatilaka, CrystEngComm, 2009, 11, 19–32;
M. A. Spackman, J. J. McKinnon and D. Jayatilaka, CrystEngComm,
2008, 10, 377–388.
21 G. Cavallo, P. Metrangolo, T. Pilati, G. Resnati, M. Sansotera and G.
Terraneo, Chem. Soc. Rev., 2010, 39, 3772–3783.
22 G. R. Desiraju and T. Steiner, The Weak Hydrogen Bond in Structural
Chemistry and Biology, Oxford University Press, 1999.
23 G. M. Sheldrick, Acta Crystallogr., Sect. A, 2008, 64, 112.
3 A. J. Blake, N. R. Brooks, N. R. Champness, L. R. Hanton, P.
Hubberstey and M. Schro¨der, Pure Appl. Chem., 1998, 70, 2351–2357.
4 S. A. Barnett, A. J. Blake, N. R. Champness and C. Wilson, Chem.
Commun., 2002, 1640–1641; A. J. Blake, N. R. Brooks, N. R. Champ-
ness, M. Crew, L. R. Hanton, P. Hubberstey, S. M. Parsons and M.
Schro¨der, J. Chem. Soc., Dalton Trans., 1999, 2813–2817; A. J. Blake,
N. R. Champness, M. Crew, L. R. Hanton, S. Parsons and M. Schro¨der,
J. Chem. Soc., Dalton Trans., 1998, 1533–1534.
12264 | Dalton Trans., 2011, 40, 12257–12264
This journal is
The Royal Society of Chemistry 2011
©