Supporting Information

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1 Supporting Information Wiley-VCH Weinheim, Germany

2 1 Calix[4]pyrrole: An old yet new ion-pair receptor Radu Custelcean, Lætitia H. Delmau, Bruce A. Moyer,* Jonathan L. Sessler,* Won-Seob Cho, Dustin Gross, Gareth W. Bates, Simon J. Brooks, Mark E. Light and Philip A. Gale* Solution studies: Figure S1 NMR spectra of 1 with TBACl and CsBPh 4 in acetone-d 6 /2%D 2 O (from top to bottom: 1, 1 +3TBACl, 1 + 3TBACl +2CsBPh 4, 1 + 3TBACl + 7CsBPh TBACl 1 + TBACl + 2 equiv. CsBPh TBACl + 7 equiv. CsBPh 4 NH CH Table S1 NH and CH resonances (ppm) for the spectra shown in Figure S1.

3 2 Addition of CsClO 4 to a complex of 1 and TBA-Cl gave rise to shifts that are in the direction back towards those of free 1. This is true for both the NH and beta-ch peaks. However, the extent of this "shifting back" is significantly larger for the CH than the NH (normalized to the total expected change one would expect if total chloride anion decomplexation were occurring). The effect therefore cannot be attributed to ion pairing (partial pulling away of a bound Cl - from the calix[4]pyrrole NH with accompanying changes for the beta-ch signals). Because of poor solubility of CsBPh 4, even in acetoned 6 containing 2% D 2 O (v/v), the exact quantity of CsBPh 4 was calculated based on a comparison of the integration of the pyrrolic CH and the CH from the phenyl of tetraphenylborate. Figure S2 Proton NMR spectra of a) 1 (10mM in nitrobenzene-d 5 ); b) equiv. TBACl; c) equiv. TBACl equiv. CsBPh 4 ; d) equiv. TBACl equiv. CsBPh 4 ; e) equiv. TBACl equiv. CsBPh 4

4 3 Peak Compound TBACl +1.0CsClO 4 % shift back -NH CH CH Table S2 NH, pyrrole CH and CH3 proton resonances for compound 1 (10mM) in nitrobenzene-d5 (1, TBACl, TBACl, TBACl CsBPh 4. The NMR of compound 1 in nitrobenzene-d 5 was measured ( MHz; C 6 D 5 NO 2, 23 C): δ 1.53 (24H, -CH 3 ), 5.85 (8H, J = 2.1 Hz, d, =CH), 7.78 (4H, -NH). Upon addition of a small stoichiometric excess of tetrabutylammonium chloride (about 1.2 times), the NH resonance shifts downfield by 4 ppm, in agreement with the hydrogenbonding of 1 to the chloride ion, and therefore a strong deshielding of the neighboring protons (Figure S2). The methyl groups remain equivalent at room temperature, indicating a fast molecular conversion compared to the NMR timescale. They, too, are shifted downfield by about 0.5 ppm. The CH signals are slightly shifted upfield, probably due to the larger polarization of the NH bond that leads to a larger electron contribution to the aromatic ring. Upon addition of approximately 1.0 equiv. CsBPh 4 to this solution, the pyrrole CH protons shifted back toward their initial resonance by 25% (Table S2) whilst the NH protons only shift back by approximately 1.49%. This finding again suggests that the cesium cation occupies the calixpyrrole cavity (and the shift back is not caused by sequestration of the bound chloride from the calixpyrrole complex).

5 4 Figure S3 NMR spectra of a) meso-octamethylcalix[4]pyrrole (1); b) 1-n-butyl-3- methylimidzolium chloride (2); c) 1-n-butyl-3-methylimidzolium tetrafluoroborate; d) meso-octamethylcalix[4]pyrrole (1) equiv. tetrabutylammonium chloride; e) mesooctamethylcalix[4]pyrrole (1) equiv. 1-n-butyl-3-methylimidzolium chloride (2); f) meso-octamethylcalix[4]pyrrole (1) equiv. 1-n-butyl-3-methylimidzolium tetrafluoroborate;(g) meso-octamethylcalix[4]pyrrole (1) equiv. 1-n-butyl-3- methylimidzolium tetrafluoroborate equiv. tetrabutylammonium chloride; h) mesooctamethylcalix[4]pyrrole (1) equiv. 1-n-butyl-3-methylimidzolium chloride (2) equiv. tetrabutylammonium chloride in CD 2 Cl 2.

6 5 Proton NMR experiments were carried out on solutions of 10mM mesooctamethylcalix[4]pyrrole in deuterated dichloromethane in the absence and presence of 1.0 equivalents of tetrabutylammonium chloride, 1-n-butyl-3-methylimidzolium chloride (2) and 1-n-butyl-3-methylimidzolium tetrafluoroborate (BMIMBF 4 ) (Figure S3). The addition of the tetrafluoroborate salt to the calixpyrrole caused only insignificant changes to the 1 H NMR spectrum. Upon addition of tetrabutylammonium chloride, the NH resonance of the calix[4]pyrrole shifted downfield to 8.95ppm. Similarly upon addition of 1-n-butyl-3-methylimidzolium chloride to the calix[4]pyrrole, the calix[4]pyrrole NH resonances shifted downfield to ppm. However, in contradistinction to the results obtained upon addition of the tetrafluoroborate salt to 1, addition of 2 led to upfield shifts of the imidzolium protons in the 2-, 4- and 5- positions (to 7.26, 6.42 and 6.11ppm). These shifts may be caused by shielding due to inclusion of the imidazolium cation in the electron rich cavity of the calix[4]pyrrole. This is not observed upon addition of BMIMBF 4 as in this case the innocent tetrafluoroborate anion does not interact with the macrocycle and hence does not pre-organise the cavity. An alternate explanation for the shifts of imidazolium cation in 2 upon addition to the calix[4]pyrrole solution might be that the calix[4]pyrrole is competing with the imidazolium cation for the chloride in solution and hence the macrocycle is diminishing the interaction between the ion-pair leading to changes in the imidazolium NMR resonances. However, the fact that innocent tetrafluoroborate salt of the same cation has imidazolium CH resonances at 8.83 and 7.21 ppm suggests that this upfield shift upon addition of 2 to 1 is not caused by perturbations of the interaction between the imidazolium chloride ion pair but rather by inclusion of the cation in the calix[4]pyrrole cavity in solution. Upon addition of 1.0 equivalents of tetrabutylammonium chloride to a solution of the macrocycle in the presence of 1.0 equiv. BMIMBF 4, upfield shifts of the imidazolium cation are again observed consistent with the added chloride pre-organising the cavity of the macrocycle so triggering inclusion of the cation.

7 6 The solid state: Figure S4 Complex 1-2. Thermal ellipsoids drawn at the 35% probability level

8 7 Figure S5 Side (above) and top (below) view of a space filling representation of imidazolium (shown in red) inclusion in the cavity of the meso-octamethylcalix[4]pyrrole chloride complex in 1-2. The calix[4]pyrrole chloride complex is rendered translucent in the side view to show penetration of the imidazolium in the calix[4]pyrrole cavity.

9 8 Figure S6 An alternate space filling representation of the coordination chain in 1-2. The imidazolium cations are shown in red. The non-acidic hydrogen atoms on the calix[4]pyrrole and the solvent are omitted for clarity. Figure S7 Diagram showing the binding of the chloride in 1-2 via strong N-H Cl hydrogen bonds and weaker C-H Cl contacts. The dichloromethane and water molecules and certain hydrogen atoms are omitted for clarity.

10 9 Figure S8 The coordination chain in 1-2. Figure S9 Complex 1-3. Thermal ellipsoids drawn at the 30% probability level

11 10 Figure S10 The coordination chain in 1-3. Figure S11 Space filling representation of the coordination chain in 1-3. The imidazolium cations are shown in red. The non-acidic hydrogen atoms on the calix[4]pyrrole and solvent are omitted for clarity.

12 11 Figure S12 Complex 1-4. Thermal ellipsoids drawn at the 30% probability level Figure S13 A space filling representation of imidazolium (shown in red) inclusion in the cavity of the meso-octamethylcalix[4]pyrrole bromide complex in 1-4. The calix[4]pyrrole chloride complex is rendered translucent.

13 12 Figure S14 The X-ray crystal structure of 1-5. Thermal ellipsoids drawn at the 30% probability level Figure S15 A bifurcated hydrogen bond is observed between N4 and O1 and O4 in the methylsulfate complex of 1.

14 13 Figure S16 A spacefilling representation of imidazolium methyl group inclusion in the meso-octamethylcalix[4]pyrrole methylsulfate complex cavity in 1-5. The imidazolium cation is shown in red and the calix[4]pyrrole anion complex is rendered translucent for clarity.