Constructing Multicomponent Materials Containing Cavitands, and

of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia ... which are π-stacked through the calixarenes in a head-t...
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DOI: 10.1021/cg900710c

Constructing Multicomponent Materials Containing Cavitands, and Phosphonium and Imidazolium Cations

2009, Vol. 9 4497–4503

Irene Ling,† Yatimah Alias,*,† Alexandre N. Sobolev,‡ and Colin L. Raston‡ †

Chemistry Department, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia , and Centre for Strategic Nano-Fabrication, School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia

‡

Received May 13, 2009; Revised Manuscript Received August 12, 2009

ABSTRACT: Bis-imidazolium cations, 1,10 -[1,4-phenylenebis(methylene)]bis(3-R-1H-imidazolium-1-yl), (R = methyl or n-butyl), form discrete multicomponent complexes in water with various phosphonium cations, anionic p-sulfonatocalix[4]arene, and aquated gadolinium(III) ions. The terminal alkyl groups, R, reside in the cavities of the calixarenes, with two calixarenes either adjacent to each other, where they face the same direction and are in the same bilayer arrangement made of calixarenes and phosphonium cations, or where they face opposite directions. Here the calixarenes are similarly part of a bilayer arrangement, or they are part of an extended structure which can be regarded as being built from the assembly of supermolecules or “molecular capsules”, [(bis-imidazolium)⊂(p-sulfonatocalix[4]arene)2], which are π-stacked through the calixarenes in a head-to-tail fashion. The nature of the product depends on the length of the terminal alkyl group, and the choice of phosphonium cation.

Introduction Self-assembly involves molecular recognition events with some complementarity of inherently weak interactions, and is a paradigm in building new material. Water-soluble sulfonated calixarenes have been extensively investigated as supramolecular tectons (or building blocks) in crystal engineering, and supramolecular chemistry in general. p-Sulfonatocalix[4]arene is the smallest oligomer for these macrocycles and is usually in the cone conformation, where it often assembles in the solid state in the up-down antiparallel bilayer arrangement, simultaneously creating hydrophobic and hydrophilic environments.1 The bilayer arrangement serves as a platform in the construction of material that mimic the structure and properties of naturally occurring clays. p-Sulfonatocalix[4]arene can also assemble into more complex arrays, including icosahedral and cuboctahedral arrangements, with the cavities directed away from their surfaces,2,3 and “Russian doll” and “ferris wheel” type arrangements.4 These arrangements, and the bilayer arrangement, can include metal ions, and organic molecules, with the calixarene being versatile in binding a range of molecules of different sizes and shapes.4 The sulfonate groups in p-sulfonatocalixarenes in general provide anchoring points for the complexation of organic and inorganic guest molecules, as well as metal ions.5 A systematic study on the interplay of Ph4Pþ with p-sulfonatocalix[4]arene using a combinatorial approach generated an extensive library of compounds, depending on the ratio of the ions, pH, and the ionic strength of the solutions.6,7 Two major findings have been described: (i) the ability to form pseudopolymorphic phosphonium complexes with one of the phenyl groups of the cation residing in the cavity of the calixarene, and (ii) the arrangement of phenyl embraced phosphonium cations around the calixarene.8 Imidazolium cations feature extensively in ionic liquids, which are rapidly gaining prominence through their diversity

of applications in synthesis, materials science, and more.9 It is noteworthy that the amphiphilic nature of ionic liquids based on imidazolium cations results in their aggregation which is similar to the behavior of cationic surfactants, and long-chain imidazolium cations can self-organize to form micelles and lyotropic liquid crystals.10 Related to this is the organization of ionic liquids based on imidazolium cations whereby the anions and cations are arranged alternately.11 Solid-state structures of imidazolium ionic liquids themselves show an interesting interplay of the ions, forming both hydrophilic and hydrophobic channels associated with the arrangement of the alkyl groups.10,12 Recently, the synthesis of ionic liquids based on bis-imidazolium cations was reported.13 We have prepared such cations and show herein that they are flexible in building multicomponent ionic solids, in conjunction with p-sulfonatocalix[4]arene, and selected phosphonium cations, along with aquated gadolinium(III) ions. Specifically, we have prepared and structurally authenticated complexes containing the designer cations: 1,10 -[1,4-phenylenebis(methylene)]bis(3methyl-1H-imidazolium-1-yl) (2) and 1,10 -[1,4-phenylenebis(methylene)]bis(3-butyl-1H-imidazolium-1-yl) (3) and the phosphonium cations, 4-6, Scheme 1. We show that the terminal groups of the bis-imidazolium cations, 2 and 3, bind in the cavities of two calixarenes which are either facing each other and from adjacent bilayers, or face the same direction in the same bilayer; these type of arrangements are comparable to the inclusion of methyl and benzyl viologens in the p-sulfonatocalix[4]arene system.14 Results and Discussion

*To whom correspondence should be addressed. Fax: þ603-79674193. E-mail: [email protected].

The combinations of components, which afforded crystals of complexes I-IV, are summarized in Table 1. The complexes were grown using an equimolar amount of each component with excess of aquated gadolinium(III) ions (typically 3 mol equivalents). In all structures, the terminal parts of the dications reside in the cavities of two calixarenes and are selectively drawn into the space between the phenyl embraced layers of

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the phosphonium cations. Beyond electrostatic consideration, there is the complementarity of the termini of the dication with the cavity of the calixarenes, winning out over binding of a phenyl ring of the phosphonium cation. Such interaction of phosphonium cations is found in several structures.6 The choice of the bis-imidazolium dication predetermines the way the phosphonium cations interplay with themselves and the calixarenes. Assembling phosphonium cations at the back of the calixarene molecule has been established for the same type of interplay of the phosphonium cations, and also for more complex bis-phosphonium cations.6,15

Scheme 1. Component Structures of 1-6

Complexes I and II

Table 1. Summary of the Components 1-6 Affording Crystalline Complexes which Have Been Structurally Authenticated Components

complex I complex II complex III

1 √ √ √

2 √ √

3 √

4 √ √

5

6 √

Figure 1. Arrangements of sulfonated calixarenes and bis-imidazolium cations (blue) bridged by gadolinium metal ion for (a) complex I and (b) complex II.

The N-methyl bis-imidazolium derivatives have the coneshaped calixarene in the “up-down” bilayer arrangement with the termini of the cation residing in cavities of two calixarenes from different bilayers, Figure 1. This effectively creates molecular capsules made up of two calixarenes from adjacent bilayers with the equatorial plane containing aquated Gd3þ ions bridging the calixarenes through extensive hydrogen bonding. In complex I there are two aquated metal ions per capsule, whereas in complex II there is only one. For complex I, a mixture of different homoleptic coordinated water environments were identified for Gd3þ, either as eight or nine coordinated species. In complex II, a partially occupied chlorine atom was modeled close to a partially occupied aquated Gd3þ. It is interesting to note that the core of the molecular capsules which contains the N-methyl bis-imidazolium cation have different molecular configurations. The molecular capsules in complex I are skewed with the bisimidazolium cations in a trans-configuration. This capsule arrangement is common where there is a directing influence from molecules confined in the cavity as in complexes with crown ethers where the crown ether spans the bilayers.16 The bis-imidazolium cations in complex II take on the eclipsed cisconfiguration, being crystallographically imposed with the molecular capsules having a mirror plane bisecting the calixarenes. Within the unit cell of complex I, there are two centrosymmetric bis-imidazolium cations, with a similar trans-configuration of the imidazolium groups relative to the central

Figure 2. (a)(i) and (b)(i): Arrangement of bis-imidazolium cations residing in the cavities of calixarenes in complex I, showing nearest contacts. (a)(ii) and (b)(ii): Space filling showing only the lower portion of a bis-imidazolium cation.

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Figure 3. (i) Close contacts of the bis-imidazolium cation residing in the cavity of the calixarene in complex II, and (ii) space filling showing only the lower portion of the bis-imidazolium cation.

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Figure 5. Packing diagram (viewing along the c-axis) in complex II showing the arrangement of bis-imidazolium cations (blue) and phosphonium cations (purple) (water molecules are omitted for clarity).

Figure 4. Packing diagram (viewing along the a-axis) in complex I showing the arrangement of bis-imidazolium cations (blue) and phosphonium cations (purple) (water molecules are omitted for clarity).

phenyl ring, and a very similar interplay of the methyl groups within the cavities of the calixarenes, Figure 2. However, they differ significantly in the orientation of the five member rings such that one dication has an imidazolium C-H directed toward sulfonate groups, with the C 3 3 3 O distance at 3.14 (3) A˚, Figure 2a(i), whereas the other dication has methylene groups directed toward the sulfonate groups, with the C 3 3 3 O distance at 3.07(6) A˚, Figure 2b(i). Other close contacts of the dication to calixarene involve C-H 3 3 3 π interactions directed toward ring centroids, which are summarized in Figure 2. In complex II the dications reside on crystallographic mirror planes which bisect the central phenyl ring, thereby having a cis-configuration, Figure 3. Here the methylene groups are directed toward sulfonate groups and the orientation of the five member rings relative to the calixarene cavities is different to the orientations in complex I. Closest contact involves C-H 3 3 3 π (centroid) for methyl and C-H groups, 2.59 and 2.82 A˚, respectively, Figure 3, with the C 3 3 3 O distance for a sulfonate group at 3.30 (2) A˚. The aquated gadolinium(III) ion has close contacts to the sulfonate groups, with Gd-O 3 3 3 O at 2.78 (2) A˚. Angles between the planes defined by the four phenyl rings of a calixarene with respect to the basal plane of the calixarene, which is defined as the four O-atoms of the hydroxyl groups at the lower rim, for complex I are 72.2° (3), 57.3(4)o, 66.3(4)o, and 37.8(4)o for one calixarene, and 73.2(4)o, 51.0(4)o, 53.9(4)o, and 39.5(4)o for the other. In complex II, the corresponding angles are 62.6(4)o, 48.2(4)o, 38.6(3)o, and

Figure 6. Partial space filling of complex I showing the arrangement of phosphonium cations (purple) within a single bilayer.

Figure 7. Packing diagram of complex II showing the space filling for phosphonium cations within a single bilayer.

65.1(3)o. In both structures the calixarenes are therefore classified as close to having a pinched cone with two opposite phenyl rings directed toward the plane of the imidazolium moiety, with the other two phenyl rings splayed apart, Figures 2(a)(ii), 2(b)(ii), and 3(ii). The selectivity of inclusion of cations in different parts of the structures is consistent for both structures, with the bisimidazolium cations between the bilayers and the phosphonium cations embedded in between the back-to-back

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Figure 8. Arrangements of sulphonated calixarene and N-butyl bis-imidazolium cation (blue) in complex III (a), and complex IV (b).

and have CH 3 3 3 π (centroid) interactions involving C-atoms from calixarene methylene groups, with the C 3 3 3 π distances at 3.61 and 3.64 A˚. Phosphonium cations bearing a benzyl group in complex II have an offset face-to-face (off) interaction between molecules with the C 3 3 3 π (centroid) distance for a phenyl ring at 3.64 A˚. The phosphonium cations also have C-H 3 3 3 π interactions involving the H-atom to the calixarene centroid aromatic ring, with C 3 3 3 π at 2.95 A˚, and CH 3 3 3 π (centroid) interaction for a methylene bridge C-atom of calixarene to the phenyl group of a phosphonium cation, with C 3 3 3 π at 3.53 A˚. Complexes III and IV

Figure 9. Packing diagram (viewing along a-axis) in complex III showing the arrangement of bis-imidazolium cations (blue) shrouded by phosphonium cations (purple) (water molecules are omitted for clarity).

orientated calixarenes in the complex bilayer arrangement, Figures 2 and 3. This presumably relates to optimizing the interplay of hydrophobic components of the cations with the calixarenes, with the hydrophobic cavities binding the termini of the imidazolium cations, and the phosphonium cations associated through optimizing the hydrophobic interplay of the large cations with the aromatic rings of the calixarenes, exo- to their cavities. Beyond the hydrophobic-hydrophobic interactions, the electrostatics are important in the overall cohesion of complexes. The distance between the bilayers in complexes I and II, respectively, is 19.6 and 21.4 A˚, Figures 4 and 5. This is defined as the distance between the central planes of one bilayer relative to the central plane of the next. In the extended array of the “capsular packing”/bilayers, hydrophilic channels are filled with water molecules between the bilayers, for both structures. Despite the presence of different phosphonium cations, with one phenyl group replaced by a benzyl group for I relative to II, the packing of the calixarenes and phosphonium cations is in bilayers for both structures. This demonstrates the versatility of the calixarene to accommodate hydrophobic cations in forming bilayer structural motifs. The phosphonium cations fill the spaces between calixarenes in complex I, while in complex II, phosphonium molecules are closely arranged in a compact layer with common multiple embrace arrangements, Figures 6 and 7. Phosphonium molecules in complex I are closely packed in an edge-to-face (ef) manner,

Complexes III and IV contain the bis-imidazolium cation with terminal n-butyl chains, with each chain residing in the cavity of a calixarene, like in complexes I and II, but the structures are now distinctly different to these, and distinctly different with respect to each other. This relates to the new flexible and larger alkyl groups attached to the imidazolium cations, and presumably subtle changes in the nature of the phosphonium cations. The striking feature of the structure of III is the presence of two calixarenes facing each other, sharing a common bisimidazolium cation with the ends of the alkyl chains residing in the cavities of the calixarenes. This gives the appearance of a molecular capsule type arrangement of calixarene, with the phosphonium cations in the equatorial plane shrouding the central part of the dication, Figure 8a. These phosphonium cations are likely to circumvent the formation of bilayers, of the type found in the structures I and II, where the phosphonium cations are embedded in the bilayer, behind the calixarenes. The “molecular capsules” in III are connected via π-π stacking of the calixarenes, which are also surrounded by the phosphonium cations. There is a layer of cations, both imidazolium and phosphonium, running through the structure, Figure 9, and channels filled with water molecules. Partial occupancy of different homoleptic coordinated water environments are identified for Gd3þ, where it is either as an eight or nine coordinated species. There are two crystallographically independent centrosymmetric bis-imidazolium cations with very similar interplay of the butyl groups with the cavity of the calixarenes, Figure 10. For one of these cations the closest contact to the calixarene involves a H-atom from the imidazolium five member ring to an O-atom of a sulfonate group of the calixarene, with C 3 3 3 O at 2.99 (2) A˚, and the H-atom of the

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Figure 10. (a)(i) and (b)(i): Bis-imidazolium cations of different configurations residing in the cavity of the calixarene in complex III showing close contacts. (a)(ii) and (b)(ii): Corresponding space filling images, but not for all of the cations.

Figure 11. Space-filling diagram of complex III showing phosphonium cations in a single bilayer.

butyl group close to an O-atom of a sulfonate group at 3.15 (2) A˚. There are three C-H 3 3 3 π contacts associated with the Hatom of the butyl chain with C-H to centroid of the phenyl rings at 2.80, 2.81, and 2.97 A˚, Figure 10a(i). For the other bisimidazolium cation, there are close C-H 3 3 3 O distances for the C-atom from the imidazolium five member ring to an O-atom of a sulfonate group of the calixarene, with C 3 3 3 O at 3.10 (1) A˚ and 2.90 (1) A˚. Other close contacts involve the H-atom from the bis-imidazolium methylene bridge group to the O-atom of the sulfonate group with C 3 3 3 O at 3.45 (1) A˚. The angles between the planes of all four phenyl rings of calixarene with respect to the four O-atoms of the lower rim for complex III are 59.4(1)o, 66.3(1)o, 43.4(1)o, 56.3(2)o for one calixarene, and 46.6(2)o, 62.9(2)o, 46.4(2)o, 72.5(2)o for another configuration. These reflect the different arrangements of the alkyl groups, with the latter having a slightly more pinched cone where the terminal part of the alkyl chain is in the cavity, Figure 10a(ii) and (b)(ii). The phosphonium molecules are embraced in an ef manner, held closely with the methylene bridge of calixarenes, with C 3 3 3 π (centroid) distances at 3.52 A˚. There are also phosphonium cation contacts to the bis-imidazolium cation, with the C 3 3 3 π (centroid) distances between the centroid of a phenyl ring in bis-imidazolium cation and the C-atom of the phosphonium cation at 3.74 A˚. Water molecules are disordered in proximity to the aquated gadolinium cations and involved to form an extended hydrogen-bond network, as evidenced by the O 3 3 3 O distances.

Complex IV, has a bilayer structure, as in complexes I and II, but with the bis-imidazolium cation associated with two adjacent calixarenes in the same bilayer. Thus, the key difference between the structures of III and IV is the presence of “molecular capsules” in III shrouded by phosphonium cations, in the absence of a bilayer, presumably because of the hydrophobic pull by the large imidazolium cation spanning two calixarenes in opposite directions. In IV the imidazolium cation interacts with the cavities of two adjacent calixarenes, and now the bilayer is seemingly able to form. The hydrophobic central part of the imidazolium cation is associated with other such cations which are not involved in a host-guest interplay with the cavities of calixarenes. In I and II the small methyl group on the imidazolium cation is unable to reside in two cavities of calixarenes within the same bilayer, and the assembly of molecular capsule is favored with the calixarenes in different bilayers. In IV one of the N-butyl bis-imidazolium cations is aligned in between two calixarenes vertically, joining two hydrophobic layers of phosphonium at the end of the chain of the bis-imidazolium cation. Separation of hydrophobic and hydrophilic layers are clearly found in the bilayers with clusters of water molecules disordered in the hydrophilic region bridged by aquated Gd3þ ions. Spanning two adjacent calixarenes in the same bilayer also has mechanistic implications on the formation of the complex. Close contacts of the bis-imidazolium cation spanning two calixarenes are shown in Figure 12a, and include (i) the H-atom from the methylene group close to the imidazolium ring and an O-atom of the sulfonate group of a calixarene, with C 3 3 3 O at 2.92 (3) A˚, (ii) H-atom from a butyl group and O-atom of a sulfonate, with C 3 3 3 O at 2.82 (4) A˚, (iii) C-H 3 3 3 O contact, involving the C-atom of the five member ring to the O-atom of a sulfonate group, at 3.04 (2) A˚, and (iv) C-H 3 3 3 π (centroid) contacts, with the distance ranging from 2.45 A˚ to 2.94 A˚. Angles between the plane defined by all four phenyl rings of calixarene with respect to the four hydroxyl groups at the lower rim for complex IV are (i) 57.6(6)o, 57.6(6)o, 46.9(5)o, and 64.9(5)o, and (ii) 41.8(4)o, 58.7(5)o, 51.7(7)o, 68.3(4)o. These reflect a slightly pinched cone conformation. The phosphonium cations assemble into a grid with the calixarenes residing within the grid network, Figure 13, the lower rim of the calixarenes being arranged back-to-back at the van der Waals limit, Figure 14. The distance between the central planes of the bilayers is 19.9 A˚, which is comparable to that in complex I. A pair of phosphonium cations in III are

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Figure 12. (a) Closest contacts of bis-imidazolium cation and calixarene in complex IV, and (b) space filling of the bis-imidazolium residing in the cavities of the calixarenes.

Figure 13. Partial space-filling diagram for complex IV along the b-axis showing the calixarenes in the crevasses of the grid built-up from the phosphonium cations.

arranged in an ef embrace with C 3 3 3 π (centroid) distances at 3.65 A˚, and close to the calixarene with C 3 3 3 π (centroid) contacts at 3.87 A˚ associated with the H-atom from the methylene bridge of the calixarene. The calixarene to phosphonium cation interplay in complexes III and IV is different from the interplay of the components in the bilayers in structures I and II. In complex III, the phosphonium cations are linked to each other with common embraces as part of a grid network, with the imidazolium cations in the openings, Figure 11. In complex IV, the phosphonium cations similarly interact within the bilayer, also forming a grid, which now incorporates the calixarenes, Figure 13. It is noteworthy that the methoxy group in the phosphonium molecule has close contacts with the calixarene, and presumably the presence of this group affects the resulting interplay of the cations. Conclusions We have successfully established the utility of bis-imidazolium cations, which were recently featured as a components in ionic liquids,13 as versatile building blocks in forming multicomponent materials with water-soluble p-sulfonatocalix[4]arene, aquated gadolinium(III) ions, and a range of phosphonium cations. The ability to prepare complexes based on the assembly of four distinctly different species is noteworthy, as is the interplay of the species in the structures depending on the nature of the phosphonium ions, and the

Figure 14. Partial space-filling diagram (viewing along the a-axis) for complex IV showing the bilayer arrangement with an N-methyl bis-imidazolium cation incorporated into two adjacent calixarenes (blue) and N-methyl bis-imidazolium cation aligned in between calixarene (orange). (Water molecules and second parts of disorder are omitted for clarity.)

length of the terminal alkyl groups on the imidazolium cations, that is, methyl versus butyl. A feature of all complexes is that the cavity of each calixarene is occupied exclusively by the termini of an imidazolium cation, with the phosphonium cations assembling in packed layers, grids, or linear arrays around the aromatic rings of the calixarene, or in the case of the structure which does not form a bilayer of calixarenes and such cations, complex III, they are arranged around a bis-imidazolium cation spanning two calixarenes in the form of a molecular capsule type arrangement. The interplay of the phosphonium cations depends on subtle changes of one substituent on these cations, which also controls building in the back-to-back arrangement of calixarenes, or circumventing the formation of close contact of these components from either face of a bilayer. This chemistry establishes a route to prepare multicomponent systems of higher complexity than previously reported for p-sulfonated calixa[4]arene, with the ability to vary the nature of the different cations. The scene is now set to translate the methodology to larger ring size calixarenes, as well as to using different metal ions, and other imidazolium cations. Experimental Section General Procedure. p-Sulfonatocalix[4]arene (1),17 1,10 -[1,4-phenylenebis(methylene)]bis(3-methyl-1H-imidazolium-1-yl) (2), and 1,10 -[1,4-phenylenebis(methylene)]bis(3-butyl-1H-imidazolium-1-yl) (3)13 were synthesized according to the literature procedures.

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)

)

Phosphonium salts 4-6 were purchased from Sigma Aldrich. A hot solution of 3-fold GdCl3 3 6H2O in water (0.5 mL) was added to a hot solution of equimolar ratios of bis-imidazolium salt and phosphonium salt with p-sulfonatocalix[4]arene in a mixture of THF and water (1:1, 2 mL, pH 1.7-3.0). The prepared solutions were left to cool and slowly evaporate, affording colorless crystals of complexes which were suitable for X-ray diffraction studies after several days. X-ray Crystallography. The X-ray diffracted intensities were measured from single crystals of the title compounds on an Oxford Diffraction Xcalibur or Gemini CCD diffractometers. Data were corrected for Lorentz and polarization effects and absorption correction applied using multiple symmetry equivalent reflections. The structures were solved by direct method and refined on F2 using the SHELX-97 crystallographic package18 and X-seed interface.19 A full matrix least-squares refinement procedure was used, minimizing w(Fo2 - Fc2), with w = [σ2(Fo2) þ (AP)2 þ BP]-1, where P = (Fo2 þ 2Fc2)/3. Agreement factors (R1 = Σ Fo| - |Fc /Σ|Fo|, wR2 = {Σ[w(Fo2 - Fc2)2]/Σ[w(Fo2)2]}1/2 and GOF = {Σ[w(Fo2 Fc2)2]/(n - p)}1/2. Non-hydrogen nondisordered atoms were refined anisotropically. The positions of hydrogen atoms were calculated from geometrical consideration and their atomic parameters were constrained to the bonded atoms during the refinement. No hydrogen atoms were located for the included water molecules. CCDC deposition numbers 725251-725254. Crystal Data for Complex I. 2(C28H20O16S44-), 2(C24H20Pþ), C16H20N42þ, Gd3þ, Naþ, 24(H2O), C120H148GdN4NaO56P2S8, M = 3041.08, colorless prism, 0.44  0.32  0.26 mm3, triclinic, space group P1 (No. 2), a = 14.6966(2), b = 23.2019(4), c = 24.7174(4) A˚, R = 112.758(2), β = 90.418(1), γ = 104.350(1)°, V = 7479.3(2) A˚3, Z = 2, Dc = 1.350 g/cm3, μ = 0.665 mm-1, F000 = 3154, MoKR radiation, λ = 0.71073 A˚, T = 100(2)K, 2θmax = 50.0°, 117862 reflections collected, 26324 unique (Rint = 0.0544). Final GOF = 1.069, |ΔFmax| = 7.1(2) e A˚-3, R1 = 0.1500, wR2 = 0.3651, R indices based on 17881 reflections with I > 2σ(I) (refinement on F2), 1610 parameters, 260 restraints. Crystal Data for Complex II. C28H20O16S44-, 3(C28H21O16S43-), 8(C25H22Pþ), 2(C16H20N42þ), 0.67(Gd3þ), Cl-, 74(H2O), C344H439ClGd0.67N8O138P8S16, M = 7795.56, colorless needle, 0.32  0.14  0.07 mm3, monoclinic, space group P21/m (No. 11), a = 14.8754(2), b = 42.7788(9), c = 17.7690(2) A˚, β = 97.073(1)°, V = 11221.3(3) A˚3, Z = 1, Dc = 1.154 g/cm3, μ = 2.332 mm-1, F000 = 4099, CuKR radiation, λ = 1.54178 A˚, T = 100(2)K, 2θmax = 134.6°, 101425 reflections collected, 20066 unique (Rint = 0.1245). Final GOF = 1.138, |ΔFmax| = 1.8(1) e A˚-3, R1 = 0.1415, wR2 = 0.3404, R indices based on 9066 reflections with I > 2σ(I) (refinement on F2), 1159 parameters, 45 restraints. Crystal Data for Complex III. 2(C28H20O16S44-), 3(C24H20Pþ), C22H32N42þ, Gd3þ, 30(H2O), C150H162GdN4O62P3S8, M = 3519.48, colorless prism, 0.57  0.46  0.22 mm3, triclinic, space group P1 (No. 2), a = 14.3260(1), b = 22.7655(2), c = 28.1062(3) A˚, R = 112.813(1), β = 91.721(1), γ = 97.864(1)°, V = 8335.28(13) A˚3, Z = 2, Dc = 1.402 g/cm3, μ = 0.617 mm-1, F000 = 3646, MoKR radiation, λ = 0.71073 A˚, T = 100(2)K, 2θmax = 64.0°, 120 439 reflections collected, 53426 unique (Rint = 0.0255). Final GOF = 1.005, |ΔFmax| = 7.5(2) e A˚-3, R1 = 0.1236, wR2 = 0.3270, R indices based on 36151 reflections with I > 2σ(I) (refinement on F2), 1955 parameters, 41 restraints. Crystal Data for Complex IV. 4(C28H21O16S43-), 4(C25H22OPþ), 3(C22H32N42þ), 0.67Gd3þ, 28(H2O), C278H324Gd0.67N12O96P4S16, M = 6111.17, colorless needle, 0.23  0.13  0.09 mm3, triclinic,

4503

space group P1 (No. 2), a = 14.3665(4), b = 19.1493(6), c = 29.3847(9) A˚, R = 85.046(2), β = 76.231(2), γ = 86.048(2)°, V = 7812.6(4) A˚3, Z = 1, Dc = 1.299 g/cm3, μ = 2.835 mm-1, F000 = 3203, CuKR radiation, λ = 1.54178 A˚, T = 100(2)K, 2θmax = 125.9°, 137 482 reflections collected, 24 522 unique (Rint = 0.0816). Final GOF = 1.001, |ΔFmax| = 1.5(1) e A˚-3, R1 = 0.1850, wR2 = 0.3004, R indices based on 8521 reflections with I > 2σ(I) (refinement on F2), 1550 parameters, 340 restraints.

Acknowledgment. We would like to thank the University of Malaya for financial support from Science Fund grant (03001-03-SF0286), university research grant PS 192/2008A, University of Malaya Centre for Ionic Liquids grant (TA009/ 2008A), The University of Western Australia, and the Australian Research Council for supporting this work. Supporting Information Available: Crystallographic information files (CIF). This information is available free of charge via the Internet at http://pubs.acs.org/.

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