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Highly Interlocked Anion-Bridged Supramolecular Networks from Interrupted Imidazole-Urea Gels

Supplementary Information

Samuel J. James, Andrea Perrin, Christopher D. Jones, Dmitry S. Yufit and Jonathan W. Steed*

Instrumental and Analytical Measurements

CHN elemental microanalysis was performed using an Exeter CE-440 Elemental Analyser. All materials submitted were dried for at least three hours under vacuum in an Abderhalden drying pistol. FT-IR spectra of all solids were recorded over 24 scans on a Perkin-Elmer Spectrum 100 Series spectrometer fitted with the universal ATR sampling accessory, at a resolution of 1 cm-1. NMR experiments were all run in DMSO-d6 on a Bruker Avance 400. Liquid chromatography electrospray ionisation mass spectrometry was conducted on 1 mg ml-1 methanol solutions using a Waters Ltd. TQD mass spectrometer.

SEM samples were imaged using an FEI Helios NanoLab DualBeam microscope in immersion mode, with beam settings of 1.5 kV and 43 pA. Prior to imaging, samples were air dried for 2 days before coating with 3 nm of chromium using a Cressington 328 Ultra High Resolution EM Coating System.

Oscillatory stress sweep experiments were performed between 0.1 – 1000 Pa at a constant frequency of 1 Hz on a TA instruments AR 2000 rheometer equipped with a rough plate geometry. When preparing the sample, 2 ml of hot gelator solution was transferred to a glass cylinder sealed with vacuum grease to the lower plate. The gels were allowed 30 minutes to equilibrate before the geometry was lowered onto the sample at a pre-determined gap of 2.5 mm, and the glass cylinder gently removed before running the experiment.

Crystallography

The single crystal diffraction data for all compounds were collected at 120 K on an Agilent XCalibur diffractometer (Sapphire-3 CCD detector, graphite monochromator, λMoKα radiation λ = 0.71073 Å) equipped with Cryostream (Oxford Cryosystems) open flow nitrogen cryostat. Structures were solved and refined using the SHELX programs1 operating within the Olex2 interface,2 or using Superflip.3

Syntheses

1‐[2‐(1H‐imidazol‐4‐yl)ethyl]‐3‐(4‐methylphenyl)urea (1a)

Histamine (1.10 g, 9.9 mmol) was dissolved in anhydrous chloroform (120 ml) under gentle heating in a three necked round bottomed flask fitted with a stirrer bar, condenser, dropping funnel and flowing N2. The mixture was heated to reflux and a solution of p-tolyl isocyanate (1.32 g, 9.9 mmol) in anhydrous chloroform (10 ml) was slowly added via the dropping funnel over the course of 2 hours, before refluxing for a further 18 hours. The resulting white precipitate was

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Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2014

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filtered under reduced pressure, washed with chloroform (3 x 50 ml) and dried under vacuum in a drying pistol for three hours to yield the pure product as a white powder (2.22 g, 9.1 mmol, 92%); Anal. found: C, 63.50; H, 6.54; N, 22.93 %. Calc. for C13H16N4O: C, 63.91; H, 6.60; N, 22.93%; νmax/cm-1 3349w and 3125w (NH), 1546s (CO), 1598 (Ph C-C), 1562 and 1515 (imid. ring); δH (400 MHz; DMSO-d6; Me4Si) 11.86 (1 H, br s, H2), 8.40 (1 H, s, H7), 7.56 (1 H, d, J 1.2, H1), 7.39 – 7.15 (2 H, m, H8), 7.15 – 6.91 (2 H, m, H9), 6.82 (1 H, d, J 1.1, H3), 6.09 (1 H, t, J 5.7, H6), 3.32 (2 H, q, J 6.9 H5), 2.65 (2 H, t, J 6.9, H4), 2.21 (3 H, s, H10); δC {1H} (101 MHz; DMSO) 155.69, 138.50, 135.14, 130.05, 129.47, 118.13, 117.30, 39.57, 28.04, 20.76; m/z (LC ESI-MS) 245 [M+H]+ 244 [M]+, 489 [2M+H]+, 289, 139.

Recrystallisation from MeCN yielded single crystals of 1a. Crystal Data. C13H16N4O, M = 244.30, orthorhombic, a = 9.2520(3), b = 10.1218(3), c = 13.0422(3) Å, V = 1221.37(6) Å3, T = 120 K, space group Pn21a, Z = 4, 14717 reflections measured, 3557 unique (Rint = 0.0474). The final wR(F2) was 0.1000 (all data).

1‐[2‐(1H‐imidazol‐4‐yl)ethyl]‐3‐phenylurea (1b)

Compound 1b has been reported previously.4 Histamine (0.14 g, 1.2 mmol) was dissolved in anhydrous acetonitrile (40 ml) under gentle heating in a round bottomed flask fitted with a stirrer bar, condenser, dropping funnel and flowing N2. The mixture was heated to reflux and a solution of phenyl isocyanate (0.15 g, 1.2 mmol) in anhydrous acetonitrile (5 ml) was slowly added via the dropping funnel over the course of 2 hours, before refluxing for a further 18 hours. The solvent was then removed on a rotary evaporator, and the white residue was recrystallized from acetonitrile before drying under vacuum for three hours to yield the off-white product (0.18 g, 0.8 mmol, 64 %); δH (400 MHz; DMSO-d6; Me4Si) 11.85 (1 H, br s, H2), 8.52 (1 H, s, H7), 7.56 (1 H, s, H1), 7.38 (2 H, d, J 7.9, H8), 7.21 (2 H, t, J 7.9, H9), 6.88 (2 H, t, J 7.3, H10), 6.84 (1 H, s, H3), 6.14 (1 H, t, J 5.6, H6), 3.31-3.34 (2 H, m, H5), 2.66 (2 H, t, J 6.9, H4); δC {1H} (101 MHz; DMSO) 155.60, 141.04, 135.20, 129.08, 121.37, 118.01, 39.56, 28.05.

[Cu(1a)4Cl]Cl (2)

Compound 1a (10.0 mg, 0.041 mmol) was dissolved in a few drops of methanol in a 2 ml vial. A solution of copper(II) chloride dihydrate (0.25 eq., 1.75 mg, 0.010 mmol) in methanol (0.2 ml) was added, to yield a deep blue solution. The open vial was placed inside a larger 15 ml vial containing diethyl ether (2 ml), and the outer vial was sealed. Within 2 days, dark blue feather-like crystals of 22b formed as ether diffused into the inner vial. Anal. found: C, 56.17; H, 5.9; N, 19.96 %. Calc. for C52H64Cl2CuN16O4: C, 56.18; H, 5.8; N, 20.16 %; IR. νmax/cm-1

3273w, 3124w and 3000w (NH), 1661s (CO) 1595s (Ph C-C), 1540s and 1497s (imid. ring).

Crystal structure determination of 2

Crystal data for C52H64N16O4CuCl2: M = 1111.64 g mol-1, blue block, 0.2111 x 0.1334 x 0.104 mm3, tetragonal, space group P4/n (no. 85), a = 19.9812(6) Å, b = 19.9812(6) Å, c = 6.9508(4) Å, α = 90.0 o, β = 90.0 o, γ = 90.0 o, V = 2775.1(2) Å3, Z = 2, Dc = 1.330 g cm-1, F000 = 1166, Mo Kα radiation, λ = 0.71073 Å, T = 120 K, 2θmax = 52.0 o, 39619 reflections collected, 2730 unique (Rint = 0.1003). Final GooF = 1.042, R1 = 0.0387, wR2 = 0.0825, R indices based on 2202 reflections with I >2σ(I) (refinement on F2), 184 parameters, 0 restraints. Lp and absorption corrections applied, µ = 0.549 mm-1.

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[Cu(1a)6](NO3)22MeOH (3)

Compound 1a (10.0 mg, 0.041 mmol) was dissolved in a few drops of methanol in a 2 ml vial. A solution of copper(II) nitrate hemi(pentahydrate) (0.15 eq., 1.305 mg, 0.0056 mmol) in methanol (0.2 ml) was added, to yield a bright blue solution. The vial was sealed and set aside. Pale blue single crystals of the product formed within 24 hours. Anal. found: C, 56.41; H, 5.93; N, 21.71 %. Calc. for C80H104CuN26O14: C, 55.95; H, 6.1; N, 21.21 %; νmax/cm-1 3382w and 3142w (NH), 1662vs (CO), 1598s (Ph C-C), 1545s and 1509s (imid. ring), 1371s (NO3

-).

Crystal structure determination of 3

Crystal data for C80H104N26O14Cu: M = 1717.43 g mol-1, blue block, 0.3434 x 0.1879 x 0.1443 mm3, triclinic, space group P-1 (no. 2), a = 13.1000(7) Å, b = 13.3909(7) Å, c = 13.4410(6) Å, α = 75.123(4) o, β = 77.751(4) o, γ = 74.712(4) o, V = 2171.59(19) Å3, Z = 1, Dc = 1.313 gcm-1, F000 = 907, Mo Kα radiation, λ = 0.7107 Å, T = 120 K, 2θmax = 52.0 o, 29444 reflections collected, 8537 unique (Rint = 0.0485). Final GooF = 1.062, R1 = 0.0566, wR2 = 0.1452, R indices based on 6765 reflections with I >2σ(I) (refinement on F2), 608 parameters, 0 restraints. Lp and absorption corrections applied, µ = 0.328 mm-1.

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Analysis

Figure S1. 1 wt. % compound 1a gels in H2O/MeOH mixtures. Left to right: H2O, H2O/MeOH 2:1, H2O/MeOH 4:1, H2O/MeOH 9:1

Re-dissolve and briefly sonicate

A BFigure S2. Optical microscope images of A) a 1 wt. % compound 1a hydrogel that has cooled normally at room temperature and B) a 1 wt. % compound 1a hydrogel that has been sonicated for 3 seconds upon cooling. Note the loss of crystallinity. Both images were taken at the same magnification.

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Figure S3. SEM images of two different regions in a dried sonication-induced compound 1a hydrogel sample.

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1a 1 wt. % oscillatory stress sweep

1a gels: G′ dependence on concentration

1a gels: Change in yield point with gelator concentration

Figure S4. A) oscillatory stress sweep rheomety of a hydrogel of compound 1a, B) G′ as a function of gelator concentration in weight percent, C) concentration dependence of the yield stress. The decreased final value may reflect incomplete dissolution.

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Figure S5. SEM micrograph of the xerogel of a weak compound 1a hydrogel in the presence of 0.1 molar equivalents of Cu(NO3)2.

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Figure S6. Stress sweep rheometry of compound 1a hydrogel in the presence of increasing equivalents of Cu(NO3)2.

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Figure S7. Stress sweep rheometry of compound 1a hydrogel in the presence of increasing equivalents of ZnCl2.

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Figure S8. Stress sweep rheometry of compound 1a hydrogel in the presence of 0.05 of CuCl2, ZnCl2 and Cu(NO3)2.

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Figure S9 SEM images showing the heterogeneous structure of gels of 1a with added metal salts (left to right 0.1 equivalents of Cu(NO3)2, CuCl2 and ZnCl2).

1. G. M. Sheldrick, Acta Crystallogr. Sect. A, 2008, 64, 112.2. O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard and H. Puschmann, J. Appl. Cryst.,

2009, 42, 339.3. L. Palatinus and G. Chapuis, J. Appl. Crystallogr., 2007, 40, 786.4. Y. M. Legrand, M. Michau, A. van der Lee and M. Barboiu, CrystEngComm, 2008, 10, 490.