Supporting Information Exploring the Programmable Assembly of a Polyoxometalate-Organic Hybrid via Metal Ion Coordination

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1 Supporting Information Exploring the Programmable Assembly of a Polyoxometalate-Organic Hybrid via Metal Ion Coordination Panchao Yin, Tao Li, Ross S. Forgan, Claire Lydon, Xiaobing Zuo, Zhaoxiong Norm Zheng, Byeongdu Lee, Deliang Long, Leroy Cronin,*, and Tianbo Liu*,,± Department of Chemistry, Lehigh University, Bethlehem, PA 18015, USA X-ray Science Division, Advanced Photo Source, Argonne National Laboratory, Argonne, IL 60439, USA WestCHEM, School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK ± Department of Polymer Science, The University of Akron, Akron, OH 44325, USA *The correspondence should be addressed. Experimental details 1, General Hybrids 1, 2, and the bipyridine-tris ligand were synthesized according to literature procedures. [1] DMSO, Methanol, anhydrous ZnCl 2, EDTA, aqueous solution of TBA OH (40% w/w), and DMSO-d 6 were purchased and used without further purification. 2, Synthesis of (TBA) 4 EDTA 5 ml TBA OH (40% w/w) solution was mixed with 0.558g EDTA. The mixture was kept sonicating until EDTA was fully dissolved. The obtained solution was kept at 50 C under reduced pressure for one week until a colorless ionic liquid was obtained. The 1 H-NMR spectrum of (TBA) 4 EDTA is listed as Figure S10. 3, Preparation of the solutions for light scattering 3.0 mg of hybrid 1 or 2 was dissolved in a mixture of 3 ml DMSO and 3 ml methanol. The obtained solution was put in a 10 ml syringe and filtered through a 200 nm filter into a clean 20 ml glass vial. 4, UV-Vis monitoring the titration of hybrid 1 & 2 with ZnCl 2 5 mg of hybrid 1 was dissolved in 20 ml DMSO. 128 mg anhydrous ZnCl 2 was dissolved in 5 ml DMSO. UV-Vis spectroscopy was used to monitor absorption in the nm range over the titration of 5µL to 150 µl of the ZnCl 2 solution into the 20 ml solution of 1. 5 mg of hybrid 2 was dissolved in 20 ml DMSO. 128 mg anhydrous ZnCl 2 was dissolved in 5 ml DMSO. UV-Vis spectroscopy was used to monitor absorption in the nm range over the titration of 5µL to 150 µl of the ZnCl 2 solution into the 20 ml solution of 2. 5, 1 H NMR monitoring the titration of hybrid 1 with ZnCl 2 and (TBA) 4 EDTA S1

2 10 mg hybrid 1 was dissolved in 1 ml DMSO-d 6 and 33 mg ZnCl 2 was dissolved in 2 ml DMSO-d 6. The total volume of ZnCl 2 solution was titrated from 40 µl to 140 µl to 1 s solution. The obtained final solution was used for (TBA) 4 EDTA titration. 300 mg (TBA) 4 EDTA was dissolved in 2 ml DMSO-d µl to 80 µl (TBA) 4 EDTA solution were titrated. 6, 1 H NMR monitoring the four working cycles of hybrid 1 First Run: 10 mg hybrid 1 was dissolved in 1 ml DMSO-d 6 (0-trans) and 33 mg ZnCl 2 was dissolved in 2 ml DMSO-d 6 (ZnCl 2 -I-solution). The total volume of ZnCl 2 -I-solution was added as 140 µl to 1 s solution (1st-cis). 300 mg (TBA) 4 EDTA was dissolved in 2 ml DMSO-d µl of (TBA) 4 EDTA solution were added to the above obtained solution (1st-trans). Second Run: 123 mg ZnCl 2 was dissolved in 2 ml DMSO-d 6 (ZnCl 2 -II-solution). 1st-trans solution was filtered and only 800 µl of it was added to NMR tube for further experiments. 120 µl ZnCl 2 -II-solution was added to 1st-trans solution (2nd-cis). 100 µl (TBA) 4 EDTA was added to 2nd-cis solution (2ndtrans). Third Run: 2nd-trans solution was filtered and only 800 µl of it was added to NMR tube for further experiments. 140 µl ZnCl 2 -II-solution was added to 2nd-trans solution (3rd-cis). 100 µl (TBA) 4 EDTA was added to 3rd-cis solution (3rd-trans). Fourth Run: 3rd-trans solution was filtered and only 800 µl of it was added to NMR tube for further experiments. 140 µl ZnCl 2 -II-solution was added to 3rd-trans solution (4th-cis). 140 µl (TBA) 4 EDTA was added to 4th-cis solution (4th-trans). Fifth Run: 4th-trans solution was filtered and only 800 µl of it was added to NMR tube for further experiments. 220 µl ZnCl 2 -II-solution was added to 4th-trans solution (5th-cis). 140 µl (TBA) 4 EDTA was added to 5th-cis solution (5th-trans). 7, SAXS experimental section The SAXS experiments were performed at 12-ID-B station with X-ray energy of 12 KeV at the Advanced Photon Source of the Argonne National Laboratory. The sample to detector distance was about 2 m. A 2D CCD detector was used to acquire images with typical exposure times in the range of 1.0 s. Ruling out the cis models with amide not conjugated with aromatic ring. Two possible models with amide groups that are not coplanar to the bipyridine units, named cis 1 and cis 2 are presented in Figure A. The pair distance distribution functions (PDDF) of cis 1, cis 2, and cis II (the right model we proposed in the manuscript) were calculated and plotted to compare with the SAXS data. Obviously, cis II fits with the experimental curve much better than the other two (Figure B). The second peak from the left of the PDDF function, corresponding to the inter-pom unit distance, is further used to identify the correct model. The experimental curve and the fitting curve of cis II identically show the second peak at 21.5±0.1Å while for models cis 1 and cis 2 the second peaks locate at 20.0±0.1Å and 19.5±0.1Å, respectively. The resolution of SAXS is around 0.1 Å. S2

3 On the other hand, the energy of the cis-conformation of 1 highly relies on the repulsion of the two POM subunits and the conjugation between the amide groups and the aromatic rings. For the three models, cis II has the weakest repulsive force between the POM units due to its longer inter-pom distance. Meanwhile, as a common sense, the conjugation between the amide groups and the aromatic rings in cis II can further lower its free energy, comparing to the non-conjugated structures in cis 1 and cis 2. Overall, cis II would be the thermodynamically most stable structure among the three. Figure A. Graphical representation of the models with amide groups that are not coplanar to the bipyridine units described by the third reviewer (left, cis 1; right, cis 2). Figure B. PDDF functions of cis 1, cis 2, cis II, and experimental data. 8, Controlled self-assembly of hybrid 1 & mg ZnCl 2 was dissolved in a mixture of 3 ml DMSO and 3 ml methanol. 20 µl ZnCl 2 solution was added to the prepared light scattering solution of 1 (section 3). After LLS analysis, 80 µl (TBA) 4 EDTA solution (250 mg dissolved in 1.5 ml DMSO and 1.5 ml methanol mixture). After the dropping of scattering intensity, 60 µl ZnCl 2 solution was added to the obtained solution, whose intensity increased to a high value again (7000 kcps) with size as ca. 360 nm. S3

4 For the control experiment, 20 µl to 60 µl ZnCl 2 solution was titrated to the light scattering solution of 2. The scattering intensities of the solution were always lower than 100 kcps. 9, TEM The TEM images were taken on a JEOL JEM-2000 electron microscope operated at 200 kv. Samples for the TEM analysis were prepared by dropping a small volume of the solution sample onto a holey carbon film on copper grid. 10, Model building for trans and cis isomers The molecular structures were built with ChemBio3D and optimized by using MM2 minimization method. Since the inorganic Dawson POMs are quite rigid, MM2 should be suitable to optimize the dumbbell structures. More importantly, the SAXS results are consistent with the optimized structures, which confirm the reliability of the models. The generated data was saved as *. pdb format for SAXS analysis. 11, Static light scattering A commercial Brookhaven Instrument LLS spectrometer equipped with a solid-state laser operating at 532 nm was used for measurement of both SLS and DLS. SLS experiments were performed at scattering angles (θ) between 20 and 100º, at 2º intervals. However, due to the large fluctuations in scattered intensities at low scattering angles, we removed the data from 20-40º in the final analysis. Derived from the Rayleigh-Gans-Debye equation [2], a partial Zimm plot was used to analyze the SLS data to obtain the radius of gyration (R g ). The partial Zimm plot stems from the following approximate formula: 1/I = C(1+R g 2 *q 2 /3). Here R g is determined from the slope and the intercept of a plot of 1/I vs. q 2. 12, Dynamic light scattering DLS measures the intensity intensity time correlation function by means of a BI-9000AT multi-channel digital correlator. The field correlation function g (1) (τ) was analyzed by the constrained regularized CONTIN method [3] to yield information on the distribution of the characteristic line width Γ. The normalized distribution function of the characteristic line width, G(Γ), so obtained, can be used to determine an average apparent translational diffusion coefficient, D app =Γ/q 2. The hydrodynamic radius R h is related to D via the Stokes Einstein equation: R h = kt/(6πηd) where k is the Boltzmann constant and η the viscosity of the solvent at temperature T. From DLS measurements, we can obtain the particle-size distribution in solution from a plot of Γ*G(Γ) versus R h. The R h of the particles is obtained by extrapolating R h,app to zero scattering angle. The normalized distribution function of the characteristic line width, G(Γ), so obtained, can be used to determine an average apparent translational diffusion coefficient, D app =Γ/q 2. The hydrodynamic radius R h is related to D via the Stokes Einstein equation: R h = kt/(6πηd) where k is the Boltzmann constant and η the viscosity of the solvent at temperature T. From DLS measurements, we can obtain the particle-size distribution in solution from a plot of Γ*G(Γ) versus R h. The R h of the particles is obtained by extrapolating R h,app to zero scattering angle. 13, Video for the folding process of hybrid molecule S4

5 The movie Hybrid_Movie was made by the author and based on NMR and SAXS results. The charge-free software Picasa 3 and windows movie maker are acknowledged here. The movie can be found as another supporting file or through the link The addition of ZnCl 2 and the molecule of ZnCl 2 were omitted for clarity. S5

6 Figure S1. Molecular structure and 1 H NMR spectrum (500 MHz, 298K, DMSO-d 6 ) of the bipyridine ligand, with a partial 1 H- 1 H COSY spectrum used to aid signal assignments. Figure S2. UV-Vis monitoring of the titration of ZnCl 2 into the DMSO solution of the bipyridine ligand. A bathochromic shift of the bipyridine band from ca. 300 to 330 nm can be observed, which results from the complexation between Zn 2+ and the ligand. S6

7 Figure S3. Molecular structure of hybrid 2. Cyan polyhedron, WO 6 ; yellow polyhedron, VO 6 ; purple polyhedron, PO 4 ; black sphere, carbon atom; blue sphere, nitrogen atom; red sphere, oxygen atom, gray sphere, hydrogen atom. [4] Figure S4. UV-Vis spectroscopic monitoring of the titration of ZnCl 2 into a DMSO solution of hybrid 2. No bathochromic shift was observed. S7

8 Figure S5. 1 H-NMR monitoring of bipyridine ligand with adding ZnCl 2 and TBA EDTA. The downfield shift of hydrogen atoms of the bipyridine units and the N-H moiety after the addition of ZnCl 2 suggests the transformation from the trans to cis isomer. After adding TBA EDTA to the above solution, the chemical shifts move upfield back to their original position, indicating the transformation from the cis isomer back to trans. S8

9 Figure S6. 1 H NMR spectrum (500 MHz, 298K, DMSO-d 6 ) of hybrid 1 with a partial 1 H- 1 H COSY spectrum used to aid signal assignments. S9

10 Figure S7. Stacked partial 1 H-NMR spectra monitoring five working cycles of the hybrid 1 in DMSO-d 6 at 293K. (Refer to section 6 in SI for detailed information) S10

11 cis-isomer 30 day cis-isomer 1 day trans-isomer 30 day trans-isomer 1 day I(q) (a.u.) q (Å -1 ) Figure S8. SAXS data of the trans isomer and cis isomer of hybrid 1 measured at 1 st day and 30 day. Data are arbitrarily scaled for clarity. S11

12 Figure 9. Model for the parallel packing of the trans isomer of 1. [1] Figure S10. EDS for the TEM images confirms the existence of W, Zn, V, and Cl, which is consistent with the addition of zinc and chloride ions in the vesicle composition. S12

13 Figure S11. 1 H-NMR spectrum (500 MHz, 298K, DMSO-d 6 ) of (TBA) 4 EDTA. [S1] C. P. Pradeep, F.-Y. Li, C. Lydon, H. N. Miras, D.-L. Long, L. Xu, L. Cronin, Chem. Eur. J. 2011, 17, [S2] P. C. Hiemenz, R. Rajagopalan, Principles of Colloid and Surface Chemistry, Marcel Dekker, New York, [S3] S. W. Provencher, Comput. Phys. Commun. 1982, 27, [S4] C. P. Pradeep, M. F. Misdrahi, F.-Y. Li, J. Zhang, L. Xu, D.-L. Long, T. Liu, L. Cronin, Angew. Chem. Int. Ed. 2009, 48, S13