Autonomous motors of a metal organic framework powered by reorganization of self-assembled peptides at interfaces Yasuhiro Ikezoe, a Gosuke Washino, b Takashi Uemura, b Susumu Kitagawa, b and Hiroshi Matsui a, * a Department of Chemistry and Biochemistry, City University of New York Hunter College, 695 Park Ave., New York, NY 10065 (USA). b Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Nishikyo-ku, 615-8510, Kyoto (Japan). * to whom correspondence should be sent. E-mail: hmatsui@hunter.cuny.edu NATURE MATERIALS www.nature.com/naturematerials 1
Figures Figure S1. X-ray powder diffraction (XRPD) patterns of % distyrylbenzene (DSB)-loaded [Zn 2 L 2 ted] n, 10% DPA-loaded [Cu 2 L 2 ted] n, % DPA-loaded [Cu 2 L 2 ted] n, 30% DPA-loaded [Cu 2 L 2 ted] n, and neat DPA. L = 1,4-benzenedicarboxylate and ted = triethylenediamine. When DSB or benzene is loaded in the [Zn 2 L 2 ted] n MOF, the incorporation of these guests distorts the MOF framework, appearing as the shift of XRPD patterns as shown below.[ref 1, 2] The agreement of the trend of the peak shift between DSB-loaded MOF and DPA-loaded MOF supports the incorporation of DPA in the MOF. Reference 1. N.Yanai et al., Gas detection by structural variations of fluorescent guest molecules in a flexible porous coordination polymer. Nature Mater. 10, 787-793 (11). Reference 2. Dybtsev, D. N., Chun, H. & Kim, K. Rigid and flexible: A highly porous metal-organic framework with unusual guest-dependent dynamic behavior. Angew. Chem. Int. Ed. 43, 5033-5036 (04). 2 NATURE MATERIALS www.nature.com/naturematerials
SUPPLEMENTARY INFORMATION Figure S2. N 2 adsorption isotherms of the MOF, [Cu 2 L 2 ted] n (L = 1,4-benzenedicarboxylate), at 77 K before ( and after ( ) the incorporation of DPA (30%). The adsorption isotherm of the DPA-MOF composite shows the drastic decrease in the amount of adsorption as compared to the one for the neat MOF, clearly indicating the presence of DPA within the MOF channels. NATURE MATERIALS www.nature.com/naturematerials 3
Figure S3. Particle size distributions of (a) [Cu 2 L 2 ted] n where L is 1,4-benzenedicarboxylate (pore size of 0.75 nm) and (b) [Cu 2 L 2 ted] n where L is 1,4-naphthalenedicarboxylate (pore size of 0.57 nm) before (dotted line) and after (solid line) the incorporation of DPA (10 %) measured by laser light diffraction. In case of the MOF with pore size of 0.75 nm (a), the size distributions between the original host and the DPA-MOF composite show no change, suggesting that DPA is incorporated inside the channels and there is no leakage of DPA from the inside.[ref 3, 4] In contrast, in case of the MOF with pore size of 0.57 nm (b), the size distribution of the DPA-MOF composite is shifted to the larger range as compared to neat MOF. This size distribution change could occur due to the aggregation of host particles induced by DPAs coating outside the host channels. References: 3. Uemura, T., Hiramatsu, D., Yoshida, K., Isoda, S. & Kitagawa, S. Sol-gel synthesis of lowdimensional silica within coordination nanochannels. J. Am. Chem. Soc. 130, 9216-9217 (08). 4. Sozzani P. et al. Complete shape retention in the transformation of silica to polymer microobjects. Nat. Mater. 5, 545-551 (06). 4 NATURE MATERIALS www.nature.com/naturematerials
SUPPLEMENTARY INFORMATION Figure S4. The optical microscopic image of water surface after the DPA-MOF particles are moved for several minutes. Dark thin layers of DPA peptide became visible at the water surface. Figure S5. The effect of the extent of MOF decomposition on the velocity of MOF. The velocity of MOF is measured in aqueous solutions containing EDTA in various concentrations between 0.1 mm and 1.0 mm. In this EDTA concentration range, maximum velocity and timedependence of velocity change are not affected, indicating that the released amount of peptide guest is not influenced sensitively by the extent of dissolution of MOF. It suggests that once the exiting path of DPA is created by partial dissolution of MOF at the interface, DPA is emitted slowly and continuously in a constant rate from inside pores of MOF. NATURE MATERIALS www.nature.com/naturematerials 5
Figure S6. Velocity changes of DPA-MOF:blue (L is 1,4-benzenedicarboxylate with the pore size of 0.75 nm), phenol-mof:green (L is 1,4-benzenedicarboxylate with the pore size of 0.75 nm), phenylalanine-mof:red (L is 1,4-benzenedicarboxylate with the pore size of 0.75 nm), and DPA-MOF with a smaller pore:black (L is 1,4-naphthalenedicarboxylate with pore size of 0.57 nm), with time in an aqueous solution containing 1 mm EDTA and 2 mm NaOH. Phenol-MOF and phenylalanine-mof systems move in a short period of time at lower velocities as compared to DPA-MOF system in the beginning of launching onto EDTA solution. The initial slow movement is generated by the release of these phenol and phenylalanine molecules from highly-ordered pores of MOF, however these motions cannot last for a long time since released phenol and diphenylalanine are dispersed quickly without self-assembly at the interface and diffusions of these guest molecules lead to the termination of MOF motions in a short time. In certain cases of autonomous chemical motors, 1 surface flow velocity patterns appear to be oscillated non-linearly via Marangoni effect, however we do not observe such characteristic oscillation patterns with the MOF motor, probably due to the slower and more steady release of DPA from MOF. This slow release feature from MOF is also discussed in supplementary information S-8. 1. Kovalchuk, N. M. & Vollhardt, D. Marangoni instability and spontaneous non-linear oscillations produced at liquid interfaces by surfactant transfer. Adv. Coll. Interf. Sci. 1, 1-31 (06). 6 NATURE MATERIALS www.nature.com/naturematerials
SUPPLEMENTARY INFORMATION Figure S7. Brewster angle micrographs of air-liquid interfaces after MOFs release (a) DPA peptide, (b) phenol and (c) phenylalanine in EDTA solution. (left) before and (right) after guest- MOF particles are launched onto the interface for 4 min. (d) Brewster angle micrographs of airliquid interfaces after neat DPA peptides are dropped onto EDTA solution. (left) before and (right) after neat DPA particles are launched onto the interface for 4 min. The increase in contrast subsequent to the swimming motion of DPA-MOF system reflects changes of indices of refraction at the air water interface induced by the reorganization of crystalline peptides on the interface. Since a crystalline domain of reorganized DPAs on the interface is as small as 0.5 µm in diameter in TEM image (Figure 3-(a)), observing small and bright spots (a, right) is consistent with the TEM image, where these crystalline DPA domains are more aggregated on TEM grids after drying. No contrast change after releasing phenol and phenylalanine from MOF indicates that both phenol and phenylalanine are not reorganized to generate crystalline domains at the interface. When neat DPA was dropped onto EDTA solution, there is no organized assembly of DPA on the air-liquid interface, indicating that well-defined crystalline pore structure of MOF assists the reorganization of DPAs at the interface after released from MOF. NATURE MATERIALS www.nature.com/naturematerials 7
(a ) (b ) Before µm launching DPA-MOF particles µm After launching DPA-MOF particles onto air-liquid interface ( for 4 min) (c ) µm Before launching phenol-mof particles After µm launching phenol-mof particles onto air-liquid interface ( for 4 min) (d ) Before µm launching phenylalanine-mof particles µm After launching phenylalanine-mof particles onto air-liquid interface (for 4 min) µm Before launching neat DPA particles µm After launching neat DPA particles onto the air-liquid interface (for 4 min) 8 NATURE MATERIALS www.nature.com/naturematerials
SUPPLEMENTARY INFORMATION Figure S8. (a) The change of solubility of DPA peptides in water with ph. The absorbance peak at 260 nm of DPA/water is used as an indicator. Absorbance at ph 10 increases 70% as compared to the absorbance at ph 5, and DPA becomes soluble in water at ph 10. (b) Brewster angle micrograph. (c) Velocity of MOF when DPA-MOF system is launched onto EDTA solution at ph 10.4 (red). Blue is the velocity change in the same experiment performed at ph 4.9 of EDTA solution. In (b), (left) before and (right) after DPA-MOF particles are launched onto the interface for 4 min. NATURE MATERIALS www.nature.com/naturematerials 9
Movie legends Movie S1. The movie of the neat MOF particle motion captured by a light microscope. The neat MOF particle is descended immediately to the bottom of the EDTA solution with no transitional and rotational motions and it does not decompose visibly under the microscope in the time frame of this experimental setting. Movie S2. The movie of the neat DPA peptide particle motion captured by a light microscope. The neat DPA particle shows no transitional and rotational motions and it spreads small pieces quickly on water surface under the microscope in the time frame of this experimental setting. Movie S3. The movie of the hybrid DPA-MOF particle motion captured by a light microscope. As the hybrid DPA-MOF particle is placed in the EDTA solution, it shows vigorous motion on the surface for several minutes. Movie S4. The movie of the phenol-incorporating MOF captured by a light microscope. This particle shows no transitional and rotational motions. Movie S5. The movie to show velocity change of the DPA-MOF particle as the hexafluoropropanol is injected at 42s. Movie S6. The movie to show the motion of the DPA-MOF particle amounted in the boat illustrated in. µm µm 10 NATURE MATERIALS www.nature.com/naturematerials