Cyclodextrin-Based Supramolecular P,N Bidentate Ligands and their

Nov 29, 2010 - Université Lille Nord de France, F-59000 Lille, France .... Cyclodextrin-based PNN supramolecular assemblies: a new class of pincer-ty...
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Organometallics 2010, 29, 6668–6674 DOI: 10.1021/om100583p

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Cyclodextrin-Based Supramolecular P,N Bidentate Ligands and their Platinum and Rhodium Complexes Julien Patrigeon,†,‡,§ Frederic Hapiot,*,†,‡,§ Micha€el Canipelle,†, Stephane Menuel,†,‡,§ and Eric Monflier†,‡,§ Universit e Lille Nord de France, F-59000 Lille, France, ‡CNRS UMR 8181, Unit e de Catalyse et de Chimie du Solide, UCCS, §UArtois, F-62300 Lens, France, and ULCO, UCEIV, EA 4492, F-59140 Dunkerque, France )

†

Received June 15, 2010

We report the elaboration of supramolecular P,N bidentate ligands starting from mono-N,Ndialkylamino-β-cyclodextrins (CD) and an appropriate phosphane, namely the sodium salt of the bis(3-sodiosulfonatophenyl)(4-tert-butylphenyl)phosphane (2). The inclusion complexes stemmed from inclusion of 2 in the cavity of mono-N,N-diethylamino-β-CD (3) or monopyrrolidino-β-CD (4) have been characterized by NMR and isothermal titration calorimetry (ITC) measurements. A 1/1 stoichiometry was established for each complex, the phosphane entering the CD cavity by the primary face. High association constants of 65.000 ( 3.000 and 70.350 ( 7.000 M-1 were measured for supramolecular complexes 2⊂3 and 2⊂4, respectively. The coordination ability of these supramolecular P,N bidentate ligands with K2PtCl4 as a platinum precursor in water was demonstrated by NMR measurements. While phosphorus coordination on the platinum occurred rapidly at room temperature, heating the solution at 60 °C was required in order to access a κ2-P,N coordination mode. Complexes [κ2-P,N-Pt(2⊂3)Cl2] (5) and [κ2-P,N-Pt(2⊂4)Cl2] (6) were obtained quantitatively. Similarly, complexes [κ2-P,N-Rh(2⊂3)(acac)(CO)] (7) and [κ2-P,N-Rh(2⊂4)(acac)(CO)] (8) were synthesized by addition of an aqueous solution of 2⊂3 and 2⊂4 respectively on the Rh(CO)2(acac) rhodium precursor (acac=acetylacetonate). No variation in their 1H NMR spectra could be detected from 20 to 80 °C, suggesting that these supramolecular P,N chelate complexes are structure invariant over the temperature range.

Introduction Self-assembly has recently emerged as a highly promising strategy in catalysis to design new ligands. Early examples in the field emerge from the pioneering work of Reek and Breit who concurrently reported the elaboration of bidentates ligands by supramolecular means. Reek et al. developed a strategy based on metal-ligand interactions. They exploited the coordination ability of a nitrogen donor group on Zn(II)porphyrins to construct a library of supramolecular phosphorus-containing bidentate ligands whose catalytic properties were demonstrated in a rhodium-catalyzed hydroformylation of alkenes.1 Breit et al., for their part, focused their attention on noncovalent interactions. The self-assembly of the building blocks is then governed by hydrogen bonding and is strongly favored in aprotic solvents. Chemical assemblies were thus obtained by in situ dimerization of the tautomeric 2-pyridone/2-hydroxypyridine pair.2 From then on, Reek and Breit have expanded their respective supramolecular strategy to the preparation of a library of self-assembled bidentate ligands and studied their catalytic performances in *To whom correspondence should be addressed. E-mail: hapiot@ univ-artois.fr. Tel: þ33-321-791-773. Fax: þ33-321-791-755. (1) Slagt, V. F.; van Leeuwen, P. W. N. M.; Reek, J. N. H. Chem. Commun. 2003, 2474–2475. (2) Breit, B.; Seiche, W. J. Am. Chem. Soc. 2003, 125, 6608–6609. pubs.acs.org/Organometallics

Published on Web 11/29/2010

numerous catalytic reactions.3,4 In all cases, improvements in the performances of the catalytic system were observed, supporting the efficiency of these supramolecular approaches. Other strategies have also been developed via metal-directed self-assembly,5a-c through acid-base interaction,5d,e or via a pseudorotaxane molecule.5f (3) (a) Slagt, V. F.; R€ oder, M.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Reek, J. N. H. J. Am. Chem. Soc. 2004, 126, 4056–4057. (b) Reek, J. N. H.; R€oder, M.; Goudriaan, P. E.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Slagt, V. F. J. Organomet. Chem. 2005, 690, 4505–4516. (c) Sandee, A. J.; Reek, J. N. H. Dalton Trans. 2006, 3385–3391. (d) Jiang, X.-B.; Lefort, L.; Goudriaan, P. E.; de Vries, A. H. M.; van Leeuwen, P. W. N. M.; de Vries, J. G.; Reek, J. N. H. Angew. Chem., Int. Ed. 2006, 45, 1223–1227. (e) van Leeuwen, P. W. N. M., Ed. In Supramolecular Catalysis; Wiley-VCH: Weinheim, 2008. (f) Goudriaan, P. E.; Jang, X.-B.; Kuil, M.; Lemmens, R.; van Leeuwen, P. W. N. M.; Reek, J. N. H. Eur. J. Org. Chem. 2008, 6079–6092. (4) (a) Seiche, W.; Schuschkowski, A.; Breit, B. Adv. Synth. Catal. 2005, 347, 1488–1494. (b) Breit, B.; Seiche, W. Angew. Chem., Int. Ed. 2005, 44, 1640–1643. (c) Breit, B.; Seiche, W. Pure Appl. Chem. 2006, 78, 249–256. (d) Weis, M.; Waloch, C.; Seiche, W.; Breit, B. J. Am. Chem. Soc. 2006, 128, 4188–4189. (e) Chevallier, F.; Breit, B. Angew. Chem., Int. Ed. 2006, 45, 1599–1602. (f) Waloch, C.; Wieland, J.; Keller, M.; Breit, B. Angew. Chem., Int. Ed. 2007, 46, 3037–3039. (g) Birkholz, M.-N.; Dubrovina, N. V.; Jiao, H.; Michalik, D.; Holz, J.; Paciello, R.; Breit, B.; B€orner, A. Chem.;Eur. J. 2007, 13, 5896–5907. (h) Laungani, A. C.; Slattery, J. M.; Krossing, I.; Breit, B. Chem.;Eur. J. 2008, 14, 4488–4502.  (i) Laungani, A. C.; Breit, B. Chem. Commun. 2008, 844–846. (j) Smejkal, T.; Breit, B. Angew. Chem., Int. Ed. 2008, 47, 3946–3949. (k) Breuil, P.-A. R.; Patureau, F. W.; Reek, J. N. H. Angew. Chem., Int. Ed. 2009, 48, 2162– 2165. (l) Meeuwissen, J.; Sandee, A. J.; de Bruin, B.; Siegler, M. A.; Spek, A. L.; Reek, J. N. H. Organometallics 2010, 29, 2413–2421. r 2010 American Chemical Society

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Concurrently to the above strategies using organic solvents, we recently make use of a completely different strategy to develop supramolecular ligands in aqueous media, turning to good account, the hydrophobic interaction between the cavity of a monoamino-β-cyclodextrin (CD) (1) and an appropriate phosphane (2) (Figure 1).6 This strategy benefited from two main advantages. First, spontaneous assembly of monodentate ligands containing two different donor atoms led to the first example of a hydrosoluble supramolecular P,N heterobidentate ligand for which both the phosphorus and the nitrogen atoms were coordinated to the metal. Second, self-assembly occurred in water to give water-soluble Pt-complexes where the CD was considered as both a first and a second sphere ligand. Nevertheless, pure supramolecular bidentate complexes could only be isolated after purification of a mixture resulting from addition of 1 and 2 onto K2PtCl4 in water. Addition of methanol onto the aqueous solution was necessary to precipitate the catalytically active [κ2-P,N-Pt(2⊂1)Cl2] complex in a pure form. Herein we present the last developments on CD-based supramolecular P,N heterobidentate Pt- and Rh-complexes. The nature of the CD has especially been varied to control the basicity of the nitrogen and its coordination ability on metals. With N,N-dialkylamino-CD derivatives, pure complexes have been readily accessible with platinum and rhodium precursors. Throughout this study, we show that the use of hydrophobic effects constitutes a general method to access various self-assembled catalysts.

Figure 1. Monoamino-β-CD (1) and sodium salt of the bis(3-sodiosulfonatophenyl)(4-tert-butylphenyl)phosphane (2).

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Results and Discussion Synthesis of N,N-Dialkylamino-β-CDs. The synthesis of mono-N,N-diethylamino-β-CD (3) and monopyrrolidinoβ-CD (4) has been carried out in two steps from the monotosylated β-CD derivative as described in Scheme 1. Mono(6-O-tosyl)-β-CD is readily synthesized from native β-CD according to a procedure described in the literature.7 Subsequent reaction with diethylamine or pyrrolidine gave the monosubstituted amino-derivatives. Compounds 3 and 4 were easily isolated in 85 and 78% yields respectively after a classical

Figure 2. 2D T-ROESY spectrum or a 1/1 mixture of 2 and 3 at 25 °C in D2O.

Scheme 1. Synthesis of Mono-N,N-diethylamino-β-CD (3) and Mono-pyrrolidino-β-CD (4)

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Figure 3.

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P NMR spectrum of a 1:1 mixture of 2⊂3 and K2PtCl4 at 25 °C in D2O.

workup and characterized by NMR and MALDI-TOF mass spectrometry. The 1H NMR spectrum of 3 showed similar behavior to those classically obtained with CD derivatives. This corroborates previous studies on N-alkyl-N,N-dimethylammonium β-CD for which a magnetic inequivalence between the two ammonium methyl groups was indicative of a restrained motion of the ammonium residue, at least on the NMR time scale.8 Similarly, broadening of the 1H NMR signals were also observed for the pyrrolidine protons of 4. CD/Phosphane Inclusion Complexes. The formation of a 2⊂3 inclusion complex was first evidenced by a 2D T-ROESY NMR analysis on a 1/1 mixture of 2 and 3. A correlation was detected between the HA and HB phosphane protons and the CD inner protons H-3 and H-5, indicative of the phosphane inclusion in the CD cavity. Moreover, cross-peaks were detected between the t-Bu protons of 2 and H-3 and H-5. This observation clearly indicated the formation of a 2⊂3 supramolecular complex for which both the phosphorus and the nitrogen atoms were located on the same side of the CD (Figure 2). Correlations between the t-Bu protons and H-6 would have been detected for an inverse inclusion of 2 in the cavity of 3. Isothermal titration calorimetry (ITC) definitely confirmed the interaction between 2 and 3 (Supporting Information) in a 1/1 stoichiometry. The binding constant between 3 and 2 (KA=65.000 ( 3.000 M-1) was also calculated by ITC. The high KA value ensured the stability of the supramolecular complex. Upon inclusion, the phosphorus of 2 was downfield shifted from -7.18 to -7.22 ppm. Moreover, compound 3 has (5) (a) Takacs, J. M.; Reddy, D. S.; Moteki, S. A.; Wu, D.; Palencia, H. J. Am. Chem. Soc. 2004, 126, 4494–4495. (b) Takacs, J. M.; Chaiseeda, K.; Moteki, S. A.; Reddy, D. S.; Wu, D.; Chandra, K. Pure Appl. Chem. 2006, 78, 501–509. (c) Moteki, S. A.; Takacs, J. M. Angew. Chem., Int. Ed. 2008, 47, 894–897. (d) Kuil, M.; Goudriaan, P. E.; van Leeuwen, P. W. N. M.; Reek, J. N. H. Chem. Commun. 2006, 4679–4681. (e) Kuil, M.; Goudriaan, P. E.; Tooke, D. M.; Spek, A. L.; van Leeuwen, P. W. N. M.; Reek, J. N. H. Dalton Trans. 2007, 2311–2320. (f) Pignataro, L.; Lynikaite, B.; Cvengros, J.; Marchini, M.; Piarulli, U.; Gennari, C. Eur. J. Org. Chem. 2009, 2539–2547. (6) Machut, C.; Patrigeon, J.; Tilloy, S.; Bricout, H.; Hapiot, F.; Monflier, E. Angew. Chem., Int. Ed. 2007, 46, 3040–3042. (7) Melton, L. D.; Slessor, K. N. Carbohydr. Res. 1971, 18, 29–37. (8) Binkowski, C.; Hapiot, F.; Lequart, V.; Martin, P.; Monflier, E. Org. Biomol. Chem. 2005, 3, 1129–1133.

its 1H NMR spectra strongly modified upon inclusion of 2 in its cavity. For example, when the methyl group resonances of 3 remain unchanged, the methylene groups in the R-position with respect to the nitrogen splits into two signals (Supporting Information). The magnetic inequivalence between these protons indicated that the motion of the ethyl groups was restrained, at least according to the NMR time scale. To confirm this result, an inverse heteronuclear 1 H-13C correlation sequence was performed (Supporting Information). The HSQC spectrum of 2⊂3 revealed that both 1H resonances of the methylene of 3 correlated with only one 13C signal indicating that both methylene carbons were magnetically equivalent but that both protons on each methylene group had a different chemical environment. The COSY spectrum of 2⊂3 strongly supported this assertion since a correlation peak was detected between both methylene proton resonances (Supporting Information). Therefore, the presence of the phosphane in the CD cavity emphasizes the limited ability of the diethylamino to rotate freely around the nitrogen (see above). Here again, spectroscopically speaking, 4 behaves similarly to 3. As described above for 3, the high association constant value between 4 and 2 (KA =70.350 ( 7.000 M-1) reflected the stability of the supramolecular 2⊂4 complex. Only note that the methylene of the pyrrolidine cycle in the β-position with respect to the nitrogen overlaps with the protons of the t-Bu group of 2, rendering the interpretation of the spectrum more difficult. Platinum Complexes. Knowing that N,N-dialkylamino substituents on a β-CD could easily accommodate the phosphorus of 2 on the CD primary face, the chelating properties of the self-assembled P,N bidentate could be turned to account to coordinate organometallic species. To be compared with our previous results on 2⊂1 and its platinum complexes,6 the 2⊂3 supramolecular complex was first mixed with K2PtCl4 in D2O. Phosphorus coordination on the platinum occurred rapidly at room temperature as clearly indicated on the 31P NMR spectrum (Figure 3). Indeed, the phosphorus resonance was greatly affected by the coordination, shifting from -7.22 to 20.73 ppm after a 5 min reaction time. The Pt-P bond was characterized by two satellite peaks around the main phosphorus signal with a

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JPt-P coupling constant of 2617 Hz (33.7% natural abundance of 195Pt), consistent with a phosphorus trans to a chloride.9 Conversely, at room temperature, nitrogen coordination required a longer reaction time (>3 days). Nevertheless, this problem could be easily dealt with by elevating the reaction temperature. Indeed, the reaction proceeded in 30 min only if run at 60 °C (Supporting Information). Upon heating and κ2-P,N coordination on the platinum, both methylene and H-6 proton signals were downfield shifted as already observed in the literature (Figure 4).10 Moreover, the methylene protons of one of the two ethyl groups split into two broad distinct resonances, as clearly evidenced by the 1H and HSQC NMR spectra, suggesting a nonsymmetrical environment around the nitrogen. Similarly, during the course of the reaction, the signal relative to the methyls slowly evolved to give two distinct resonances consistent with two magnetically inequivalent -CH3. The nitrogen coordination did not significantly affect the phosphorus signal. The 13C NMR spectrum was indicative of the nitrogen coordination as the

Figure 4. 1H NMR spectra of a 1:1 mixture of 2⊂3 and K2PtCl4 at 25 °C in D2O (a) 5 min, (b) 12 h, (c) 1 day, (d) 2 days, and (e) 3 days after addition of 2⊂3 on K2PtCl4.

Figure 5.

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carbon resonances of the ethyl groups were shifted from 12.2 to 10.9 for the methyls and from 48.7 to 52.2 and 50.0 ppm for the methylenes (Figure 5). The inclusion of 2 in the cavity of 3 was confirmed by correlation peaks on a T-ROESY spectrum in D2O. Concurrently, upon coordination on the platinum, the aromatic protons HA and HB of the t-BuPh moiety were significantly shielded to higher fields (for example, from 7.10 ppm to 7.32 ppm for HB) (Supporting Information). The structure of the [κ2-P,N-Pt(2⊂3)Cl2] complex (5) is depicted in Figure 6. Thus, compared to previous studies on the 2⊂1 supramolecular complex for which a mixture of platinum complexes were obtained, the reaction between 2⊂3 and K2PtCl4 proceeded cleanly since only one product was detected by NMR measurements. This emphasizes the role of the nitrogen substituents. Indeed, the higher basicity of the ethyl-substituted nitrogen of 3 (compared to 1) favored the κ2-P,N coordination on the platinum, thus avoiding the formation of mixtures.11 Moreover, the binding constant between 3 and 2 (KA = 65.000 ( 3.000 M-1) is larger than that measured for the 2⊂1 supramolecular complex (KA = 40.600 ( 3.000 M-1), thus promoting the formation of a pure Ptcomplex. The supramolecular complex 2⊂4 behaves similarly to 2⊂3, leading to the complex [κ2-P,N-Pt(2⊂4)Cl2] (6) after coordination on the platinum (Figure 6). Just note that when the nitrogen of 4 coordinated the platinum, the methylenes of the pyrrolidine cycle that were in the β-position with respect to the nitrogen did not overlap anymore with the t-Bu signal on the 1H NMR spectrum since they were downfield shifted from 1.43 to 1.57 ppm and appeared as a broad resonance,

Figure 6. Structures of Pt-complexes 5 and 6.

C NMR spectra of 2⊂3 (up) and its platinum complex 5 (down) at 25 °C in D2O.

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Figure 7.

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P NMR spectrum of 7 at 25 °C in D2O.

suggesting a restrained motion of the pyrrolidine cycle. Here again, the nitrogen coordination was borne out by 13C and 31 P NMR spectrometry as shifts were detected for atoms in the direct environment of the coordination sites. Thus, as anticipated, the Pt-complexes derived from N,Ndialkyl amino β-CD were more easily obtained than those synthesized from 1. In a way, the basic and bulky characters of the alkyl substituents force the nitrogen to coordinate on the metal. Rhodium Complexes. Once the coordination on platinum was demonstrated and compared to previous results, the organometallic study was extended to rhodium complexes. Complex [κ2-P,N-Rh(2⊂3)(acac)(CO)] (7) (acac = acetylacetonate) was synthesized by addition at room temperature of an aqueous solution of 2⊂3 on the Rh(CO)2(acac) rhodium precursor. Only one doublet (JRh-P = 178 Hz) could be detected on the 31P NMR spectrum (Figure 7). The resonance was strongly shifted from -7.22 ppm (noncoordinated phosphane included in the CD cavity) to 48.68 ppm (included phosphane coordinated on the rhodium). The structure of 7 and the selectivity of the P,N chelation on the rhodium precursor were borne out by the 1H NMR spectrum since chemical shift variations were detected for the nitrogen-bounded methylene groups (Supporting Information). The CH3 protons of the ethyl groups were only slightly shifted, but chemical shift variation of the methyl carbon on the 13C NMR spectrum confirmed the nitrogen coordination to rhodium. The acac methyl groups appeared as two (9) Milton, H. L.; Wheatley, M. V.; Slawin, A. M. Z.; Woollins, J. D. Inorg. Chem. Commun. 2004, 7, 1106–1108. (10) J anosi, L.; Kegl, T.; Hajba, L.; Berente, Z.; Kollar, L. Inorg. Chim. Acta 2001, 316, 135–139. (11) Andrieu, J.; Camus, J.-M.; Richard, P.; Poli, R.; Gonsalvi, L.; Vizza, F.; Peruzzini, M. Eur. J. Inorg. Chem. 2006, 51–61.

Figure 8. Structures of Rh-complexes 7 and 8.

distinct signals, indicative of an unsymmetrical structure. Correlations relative to two different acac carbonyls on the HSQC spectrum corroborated this analysis (Supporting Information). Here again, the presence of the t-Bu-C6H4 group in the CD cavity of 2 was confirmed by T-ROESY experiment. The infrared spectrum of 7 revealed a CO band at 1981 cm-1 indicative of a CO in trans position with respect to the nitrogen.12 Note that, once 7 was synthesized, no variation in its 1H NMR spectrum could be detected from 20 to 80 °C, suggesting that the supramolecular P,N chelate complex is structure invariant over the temperature range. The structure of 7 is depicted in Figure 8. Similarly, the supramolecular 2⊂4 complex reacted in water on the Rh(CO)2(acac) rhodium precursor to give the complex [κ2-P,N-Rh(2⊂4)(acac)(CO)] (8) in quantitative yield (Figure 8). Chemical shift variation was indicative of the coordination of both the phosphorus and the nitrogen on the rhodium (Supporting Information). (12) (a) Andrieu, J.; Richard, P.; Camus, J.-M.; Poli, R. Inorg. Chem. 2002, 41, 3876–3885. (b) Phillips, A. D.; Bola~no, S.; Bosquain, S. S.; Daran, J.-C.; Malacea, R.; Peruzzini, M.; Poli, R.; Gonsalvi, L. Organometallics 2006, 25, 2189–2200.

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Conclusion The experiments reported above have shed light on CDbased supramolecular P,N heterobidentates, featuring 2⊂3 and 2⊂4 in a chelate κ2-P,N coordination mode when coordinated to Pt- and Rh-complexes. The choice of the aminoβ-CD is crucial in the self-assembling process of supramolecular Pt-complexes as it strongly determines the ease with which the nitrogen coordinates the metal. In this context, basic diethylamino and pyrrolino secondary substituents appeared much more attractive than the primary amino substituent, the former leading to pure complexes when mixtures were obtained with the latter. Rh-complexes, for their part, were readily accessible in a pure form by mixing 2⊂3 and 2⊂4 with the Rh(CO)2(acac) rhodium precursor at room temperature. Hence, self-assembly in water of organometallic complexes through noncovalent complementary interactions and metal coordination appears a versatile strategy to design new water-soluble bidentate ligands.

Experimental Section General Methods. All chemicals were purchased from Acros and Aldrich Chemicals in their highest purity. All solvents were used as supplied without further purification. Distilled water was used in all experiments. NMR spectra were recorded on a Bruker DRX300 spectrometer operating at 300 MHz for 1H nuclei, 75 MHz for 13C nuclei, and 121.49 MHz for 31P nuclei. DMSO-d6 (99.80% isotopic purity) and D2O (99.92% isotopic purity) were purchased from Euriso-Top. Signals are recorded in terms of chemical shifts and are expressed in parts per million (δ), multiplicity, coupling constants (in Hz, rounded to one decimal place), integration, and assignments in that order. The correct assignments of the chemical shifts were confirmed when necessary by two-dimensional correlation measurements attained by 1H1 H COSY, 1H-13C HSQC, or 1H-13C HMBC experiments. Mass spectra were recorded on a MALDI-TOF/TOF Bruker Daltonics Ultraflex II in positive reflectron mode with 2,5-DHB as matrix. An isothermal calorimeter (ITC200, MicroCal Inc., USA) was used for determining simultaneously the formation constant and the inclusion enthalpy and entropy of the studied complexes (2⊂1, 2⊂3, 2⊂4). General Procedure for the Synthesis of Mono-N,N-dialkyl-βCDs. Mono(6-O-tosyl)-β-CD (5.0 g, 3.9 mmol) in freshly distilled amine (150 mL) was stirred at 70 °C for 16 h. After total evaporation of the amine, the crude product was dissolved in minimum distilled water and heated at 60 °C. Cooling the solution to rt resulted in the precipitation of white crystalline needles. Filtration on a glass filter and subsequent drying under vacuum gave the expected compound. Mono-(6-deoxy-6-(N,N-diethylamino))-β-cyclodextrin (3). 85% yield. 1H NMR (300.13 MHz, DMSO-d6, 298 K): δ 5.9-5.6 (m, 14 H, OH(2) and OH(3)), 4.80 (s, 7 H, H(1)), 4.45 (m, 6 H, OH(6)), 3.9-3.4 (m, 26 H, H(3), H(5) and H(6)), 3.4-3.1 (m, 14 H, H(2) and H(4)), 2.74 (m, 1 H, H(6)sub), 2.47 (overlapped with DMSO and determined by COSY and HSQC experiments, 5 H, H(6)sub and CH2 ethyl), 0.86 (t, 3JH-H=7.1 Hz, 6 H, CH3 ethyl). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 103.1 (C(1)), 85.2 (C(4)sub), 82.4-81.8 (C(4)), 74.2-72.0 (C(2), C(3) and C(5)), 61.0 (C(6)), 55.2 (C(6)sub), 47.8 (CH2 ethyl), 12.4 (CH3 ethyl). MS: m/z calcd for [C46H79NO34]þ 1190.63, obsd 1190.11; calcd 1212.09 for [C46H79NO34 þ Na]þ, obsd 1212.60; calcd 1228.20 for [C46H79NO34 þ K]þ, obsd 1228.58. Mono-(6-deoxy-6-(N-pyrrolidinyl))-β-cyclodextrin (4). 78% yield. 1H NMR (300.13 MHz, DMSO-d6, 298 K): δ 5.8-5.6 (m, 14 H, OH(2) and OH(3)), 4.80 (s, 7 H, H(1)), 4.5-4.4 (m, 6 H, OH(6)), 3.7-3.5 (m, 26 H, H(3), H(5) and H(6)), 3.4-3.2 (m, 14 H, H(2) and H(4)), 2.69-2.63 (m, 2 H, H(6)sub), 2.42 (bs, 4

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H, CH2R partially hidden by DMSO peak), 1.59 (bs, 4 H, CH2β). 13 C{1H} NMR (75.47 MHz, D2O, 298 K): δ 102.9 (C(1)), 82.5 (C(4)), 74.0-73.0 (C(2), C(3), C(5)), 60.9 (C(6)), 56.4 (determined by HSQC experiment, C(6)sub), 55.7 (CH2R), 24.2 (CH2β). MS: m/z calcd 1188.09 for [C46H77NO34]þ, obsd 1188.34; calcd 1210.07 for [C46H77NO34 þ Na]þ, 1210.45; calcd 1226.18 for [C46H77NO34 þ K]þ, obsd 1226.41. General Procedure for the Preparation of the Supramolecular Complexes. A mixture of mono-N,N-dialkylamino-β-CD (23.80 mg, 0.02 mmol) and 2 (10.45 mg, 0.02 mmol) in D2O was stirred for 10 min providing an aqueous solution of the inclusion complex. Supramolecular Complex 2⊂3. 1H NMR (300.13 MHz, D2O, 298 K): δ 7.98 (d, 3JH-P =7.7 Hz, 2 H, Ho0 ), 7.93 (d, 3JH-H = 8.0 Hz, 2 H, Hp), 7.65 (br t, 2 H, Hm), 7.48 (br q, 2 H, Ho), 7.31 (d, 3 JH-H=7.6 Hz, 2 H, HA), 7.10 (t, 3JH-H ≈ 3JH-P=7.6 Hz, 2 H, HB), 5.03 (m, 7 H, H(1)), 4.0-3.3 (m, 40 H, H(2), H(3), H(4), H(5) and H(6)), 2.76 (m, 2 H, H(6)sub), 2.47 (m, 2 H, CH2 ethyl), 2.22 (m, 2 H, CH2 ethyl), 1.43 (s, 9 H, t-Bu), 0.76 (t, 3JH-H = 6.7 Hz, 6 H, CH3 ethyl). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 156.0 (C-ipso[t-Bu]), 146.4 (C-ipso[SO3Na]), 139.1 (Cipso[P](Ph-SO3Na)), 138.9 (Co), 135.6 (C-ipso[P](Ph-t-Bu)), 135.2 (CB), 133.9 (Co0 ), 132.5 (Cm), 129.9 (Cp), 128.1 (CA), 105.0 (C(1)), 87.3 (C(4)sub), 83.2 (C(4)), 76.1-74.6 and 71.4 (C(2), C(3), C(5)), 62.1 (C(6)), 56.5 (C(6)sub), 48.7 (CH2 ethyl), 37.5 (t-Bu quaternary C), 34.0 (CH3 t-Bu), 12.2 (CH3 ethyl). 31 P{1H} NMR (121.49 MHz, D2O, 298 K): δ -7.22 (s). Supramolecular Complex 2⊂4. 1H NMR (300.13 MHz, D2O, 298 K): δ 7.98 (m, 2 H, Ho0 ), 7.93 (m, 2 H, Hp), 7.64 (t, 2 H, 3JH-H= 7.7 Hz, Hm), 7.43 (t, 2 H, 3JH-H ≈ 3JH-P=6.9 Hz, Ho), 7.33 (d, 2 H, 3JH-H =7.7 Hz, HA), 7.15 (t, 2 H, 3JH-H ≈ 3JH-P =7.7 Hz, HB), 5.03 (m, 7 H, H(1)), 4.0-3.2 (m, 40 H, H(2), H(3), H(4), H(5) and H(6)), 2.86 (m, 1 H, H(6)sub), 2.58 (m, 1 H, H(6)sub), 2.34 (bs, 2 H, CH2R), 2.16 (bs, 2 H, CH2R), 1.43 (bs, 13 H, CH3 t-Bu and CH2β). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 156.2 (C-ipso[t-Bu]), 146.4 (C-ipso[SO3Na]), 139.3 (C-ipso[P](Ph-SO3Na)), 138.6 (Co), 135.7 (CB), 135.2 (C-ipso[P](Ph-tBu)), 133.9 (Co0 ), 132.4 (Cm), 129.8 (Cp), 128.1 (CA), 105.1 (C(1)), 87.3 (C(4)sub), 83.4 (C(4)), 76.0-74.4 and 72.5 (C(2), C(3), C(5)), 62.1 (C(6)), 59.0 (C(6)sub), 56.9 (CH2R), 37.5 (t-Bu quaternary C), 34.0 (CH3 t-Bu), 25.2 (CH2β). 31P{1H} NMR (121.49 MHz, D2O, 298 K): δ -7.29 (s). General Procedure for the Synthesis of Platinum Complexes. A mixture of mono-N,N-dialkylamino-β-CD (23.80 mg, 0.02 mmol) and 2 (10.45 mg, 0.02 mmol) in degassed D2O was stirred for 10 min in a Schlenk tube. The solution was added dropwise under N2 on K2PtCl4 (8.30 mg, 0.02 mmol). The reaction mixture was stirred at 60 °C for 30 min. After evaporation, a gray powder was obtained in quantitative yield. Complex [K2-P,N-Pt(2⊂3)Cl2] (5). Quantitative yield. 1H NMR (300.13 MHz, D2O, 298 K): δ 8.54 (br s, 1 H, Ho0 ), 8.36 (br s, 1 H, Ho0 ), 8.16 (br s, 2 H, Ho), 8.09 (br s, 2 H, Hp), 7.88 (br s, 2 H, Hm), 7.32 (br s, 2 H, HB), 7.25 (br s, 2 H, HA), 4.99 (m, 7 H, H(1)), 4.1-3.2 (m, 42 H, H(2), H(3), H(4), H(5) and H(6)), 2.96 (m, 2 H, CH2 ethyl), 2.81 (m, 1 H, CH2 ethyl), 2.55 (m, 1 H, CH2 ethyl), 1.35 (s, 9 H, CH3 t-Bu), 0.98 (br s, 3 H, CH3 ethyl), 0.72 (br s, 3 H, CH3 ethyl). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 158.0 (Cipso[t-Bu]), 146.6 (C-ipso[SO3Na]), 140.4 (Co), 138.7 (C-ipso[P](Ph-SO3Na)), 136.7 (CB), 134.6 and 133.8 (Co0 ), 134,1 (C-ipso[P](Ph-t-Bu)), 132.7 (Cm), 132.0 (Cp), 127.4 (CA), 105.0 (C(1)), 86.0 (C(4)sub), 83.7-83.0 (C(4)), 76.2-74.0 and 69.6 (C(2), C(3), C(4) and C(5)), 62.5 (C(6)), 55.3 (C(6)sub), 52.2 and 50.0 (CH2 ethyl), 37.8 (t-Bu quaternary C), 34.0 (CH3 t-Bu), 10.9 (CH3 ethyl). 31 P{1H} NMR (121.49 MHz, D2O, 298 K): δ 20.73 (s þ d, 1JP-Pt= 2617 Hz). Anal. Calcd for C64H92Cl2Na2NPO40S2Pt 3 4H2O: C, 38.54; H, 5.05; N, 0.70. Found: C, 38.45; H, 5.26; N, 0.97. Complex [K2-P,N-Pt(2⊂4)Cl2] (6). Quantitative yield. 1H NMR (300.13 MHz, DMSO-d6, 298 K): δ 8.57 (br s, 1 H, Ho0 ), 8.37 (br s, 1 H, Ho0 ), 8.18-8.09 (br s, 4 H, Ho þ Hp), 7.90 (br s, 2 H, Hm), 7.26 (br s, 4 H, HB þ HA), 4.98 (m, 7 H, H(1)), 4.1-3.2 (m, 44 H, H(2), H(3), H(4), H(5), H(6) and CH2R pyrrolidine), 2.68 (m, 1 H,

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CH2R pyrrolidine), 2.48 (m, 1 H, CH2R pyrrolidine), 1.57 (br s, 4 H, CH2β pyrrolidine), 1.35 (s, 9 H, CH3 t-Bu). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 157.9 (C-ipso[t-Bu]), 146.4 (Cipso[SO3Na]), 140.3 (Co), 138.6 (C-ipso[P](Ph-SO3Na)), 136.3 (CB), 134.8 and 133.7 (Co0 ), 134,0 (C-ipso[P](Ph-t-Bu)), 132.7 (Cm), 131.9 (Cp), 127.3 (CA), 104.9 (C(1)), 85.6 (C(4)sub), 83.4 (C(4)), 75.9-74.5 and 70.3 (C(2), C(3), C(4), and C(5)), 62.5-61.9 (C(6)), 59.1 (C(6)sub), 57.5 and 57.0 (CH2R pyrrolidine), 37.6 (tBu quaternary C), 33.9 (CH3 t-Bu), 25.5 and 24.8 (CH2β pyrrolidine). 31P{1H} NMR (121.49 MHz, D2O, 298 K): δ 20.94 (s þ d, 1JP-Pt = 2612 Hz). Anal. Calcd for C68H98Cl2Na2NPO40S2Pt 3 3H2O: C, 40.22; H, 5.16; N, 0.69. Found: C, 40.32; H, 5.38; N, 0.94. General Procedure for the Synthesis of Rhodium Complexes. A mixture of mono-N,N-dialkylamino-β-CD (23.80 mg, 0.02 mmol) and 2 (10.45 mg, 0.02 mmol) in degassed D2O was stirred for 10 min in a Schlenk tube. The solution was added dropwise under N2 on Rh(acac)(CO)2 (5.16 mg, 0.02 mmol). The reaction mixture was stirred at room temperature for 1 h. After evaporation, a gray powder was obtained in quantitative yield. Complex [K2-P,N-Rh(2⊂3)(acac)(CO)] (7). Quantitative yield. 1 H NMR (300.13 MHz, D2O, 298 K): δ 8.20 (br t, 3JH-H ≈ 3 JH-P =10.5 Hz, 2 H, Ho0 ), 7.96 (br d, 2 H, Hp), 7.60 (m, 4 H, HB þ Hm), 7.44 (br t, 3JH-H ≈ 3JH-P=9.0 Hz, 2 H, Ho), 7.34 (br d, 3JH-H=7.6 Hz, 2 H, HA), 5.00 (m, 7 H, H(1)), 4.0-3.2 (m, 41 H, H(2), H(3), H(4), H(5), H(6) and CH(acac)), 2.91 (m, 2 H, H(6)sub), 2.57 (m, 2 H, CH2 ethyl), 2.42 (m, 2 H, CH2 ethyl), 2.05 (s, 3 H, CH3(acac)), 1.66 (s, 3 H, CH3(acac)), 1.40 (s, 9 H, CH3 t-Bu), 0.75 (br s, 6 H, CH3 ethyl). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 191.6 and 191.1 (CdO (acac)), 158.5 (Cipso[t-Bu]), 146.3 (C-ipso[SO3Na]), 138.2 (Co), 136.9 (CB), 134.6 (Co0 ), 133.8 (C-ipso[P](Ph-SO3Na)), 132.6 (C-ipso[P](Ph-t-Bu)), 132.1 (Cm), 131.3 (Cp), 127.9 (CA), 105.0 (C(1)), 86.8 (C(4)sub), 83.2 (C(4)), 76.1-74.6 and 70.8 (C(2), C(3), C(4), C(5)), 62.1 (C(6)), 56.0 (C(6)sub), 49.5 (CH2 ethyl), 37.8 (t-Bu quaternary

Patrigeon et al. C), 34.0 (CH3 t-Bu), 29.3 and 29.1 (CH3(acac)), 11.7 (CH3 ethyl). 31P{1H} NMR (121.49 MHz, D2O, 298 K): δ 48.68 (d, 1 JP-Rh=178 Hz). Anal. Calcd for C70H105Na2NPO43S2Rh 3 3H2O: C, 43.33; H, 5.45; N, 0.72. Found: C, 43.48; H, 5.52; N, 0.85. Complex [K2-P,N-Rh(2⊂4)(acac)(CO)] (8). Quantitative yield. 1 H NMR (300.13 MHz, D2O, 298 K): δ 8.23 (dd, 1 H, 3JH-H = 12.1 Hz and 3JH-H =6.8 Hz, Ho0 ), 7.99 (br d, 2 H, Hp), 7.64 and 7.63 (m, 4 H, Hm and HB respectively), 7.44 and 7.39 (m, 4 H, Ho and HA respectively), 5.00 (m, 7 H, H(1)), 4.0-3.2 (m, 41 H, H(2), H(3), H(4), H(5), H(6) and CH(acac)), 2.97 (br s, 1 H, H(6)sub), 2.77 (br s, 1 H, H(6)sub), 2.53 (m, 2 H, CH2R), 2.40 (m, 2 H, CH2R), 2.08 (s, 3 H, CH3(acac)), 1.67 (s, 3 H, CH3(acac)), 1.43 (s, 13 H, CH3 t-Bu and CH2β). 13C{1H} NMR (75.47 MHz, D2O, 298 K): δ 192.1 and 191.4 (CdO (acac)), 158.5 (C-ipso[t-Bu]), 146.3 (C-ipso[SO3Na]), 138.2 (Co), 136.9 (CB), 134.5 (Co0 ), 134.0 (C-ipso[P](Ph-SO3Na)), 132.7 (C-ipso[P](Ph-t-Bu)), 132.1 (Cm), 131.4 (Cp), 127.9 (CA), 105.1 (C(1)), 86.9 (C(4)sub), 83.3 (C(4)), 76.2-74.8 and 72.4 (C(2), C(3), C(4), C(5)), 62.2 (C(6)), 58.8 (C(6)sub), 57.3 (CH2R), 37.8 (t-Bu quaternary C), 34.0 (CH3 t-Bu), 29.3 and 29.1 (CH3(acac)), 25.5 (CH2β). 31P{1H} NMR (121.49 MHz, D2O, 298 K): δ 48.9 (d, 1JP-Rh=177 Hz). Anal. Calcd for C74H111Na2NPO43S2Rh 3 3H2O: C, 44.86; H, 5.60; N, 0.70. Found: C, 44.41; H, 5.58; N, 0.88.

Acknowledgment. This work was supported by the Centre National de la Recherche Scientifique (CNRS) and the Ministere de l’Enseignement Superieur et de la Recherche. Roquette Freres (Lestrem, France) is gratefully acknowledged for generous gifts of cyclodextrins. Supporting Information Available: NMR and IR spectra and isothermal titration calorimetry details. This material is available free of charge via the Internet at http://pubs.acs.org.