SUPPLEMENTARY INFORMATION

SUPPLEMENTARY INFORMATION Supplementary Information for Ion-triggered spring-like motion of a double helicate accompanied by anisotropic twisting Kazuhiro Miwa, Yoshio Furusho* and Eiji Yashima* Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan. *e-mail: furusho@apchem.nagoya-u.ac.jp; yashima@apchem.nagoya-u.ac.jp nature chemistry www.nature.com/naturechemistry 1

supplementary information 1. Instruments Melting points were measured on a Yanaco MP-500 micro melting point apparatus and were uncorrected. NMR spectra were measured on a Varian UNITY INOVA 500AS spectrometer operating at 500 MHz for 1 H and at 125 MHz for 13 C. Absorption and CD spectra were measured using a JASCO V-570 spectrophotometer and a JASCO J-820 spectropolarimeter, respectively. Stopped-flow CD spectroscopy was measured on a JASCO J-820 spectropolarimeter with an SFS-492 stopped-flow attachment. Electrospray ionization (ESI) mass spectra were recorded on a JEOL JMS-T100CS mass spectrometer. The single-crystal X-ray data for the helicates, DH2 BNaB BMAmm + and DH2 BB 2 (BMAmm + ) 2, were collected on a Bruker Smart Apex CCD-based X-ray diffractometer with Mo-Kα radiation (λ = 0.71073 Å). 2. Materials All starting materials were purchased from commercial suppliers and were used without further purification unless otherwise noted. The boronic acid, 3 1, and the dibromide, 4 2, were prepared according to the literature. 3. Synthesis and Characterization of the Tetraphenol (2) The ligand, H 4 L2 (2), was synthesized by the Suzuki cross-coupling of 3 1 and 4, 2 followed by demethylation with BBr 3, as shown in Scheme S1. 2 Bu t MeO OMe B(OH) 2 Bu t + Br Br Pd(PPh 3 ) 4 K 2 CO 3 aq toluene, 100 C (77% yield) OMe Bu t OMe Bu t OMe Bu t OMe Bu t 3 4 5 OH OH OH OH i) BBr 3 ii) H 2 O (60% yield) Bu t Bu t Bu t Bu t 2: H 4 L2 Scheme S1. Synthesis of tetraphenol 2. 2 nature chemistry www.nature.com/naturechemistry

supplementary information 5: A mixture of 3 (800 mg, 2.16 mmol), 4 (270 mg, 0.864 mmol), and Pd(PPh 3 ) 4 (130 mg, 0.112 mmol) in toluene (8.0 ml) and 2 M aq. K 2 CO 3 (8.0 ml) was stirred at 100 C for 18 h under an Ar atmosphere. The mixture was extracted with EtOAc (80 ml). The organic layer was washed with H 2 O (40 ml) and brine (40 ml), dried over anhydrous Na 2 SO 4, filtered, and concentrated under reduced pressure. The crude product was purified by flash chromatography (SiO 2 (120 g), n-hexane/etoac = 10/0 to 8/2) to give 5 as a white solid in 77% yield. This compound was used in the next step without further purification. 1 H NMR (500 MHz, CDCl 3, 25 C, 5.3 mm) δ 7.89 (m, 2H, ArH), 7.57 7.64 (m, 4H, ArH), 7.50 (dd, J = 7.7 Hz, 7.7 Hz, 2H, ArH), 7.37 7.41 (m, 4H, ArH), 7.33 7.37 (m, 4H, ArH), 6.94 (d, J = 8.6 Hz, 2H, ArH), 3.79 (s, 6H, OCH 3 ), 3.25 (s, 6H, OCH 3 ), 1.36 (s, 18H, t-bu), 1.33 (s, 18H, t-bu). H 4 L2 (2): To a solution of 5 (1.08 g, 1.34 mmol) in CH 2 Cl 2 (42 ml) was added a 1.0 M CH 2 Cl 2 solution of BBr 3 (26.8 ml, 26.8 mmol) at 80 C under an Ar atmosphere. After being warmed to room temperature, the mixture was stirred for 17 h. Then, H 2 O (60 ml) was added to the mixture at 5 C, which was stirred for 1 h at room temperature. The mixture was then evaporated to remove CH 2 Cl 2 and the resultant aqueous solution was extracted with EtOAc (3 80 ml). The combined organic layer was washed with 1 M HCl (80 ml), H 2 O (80 ml), and brine (80 ml), dried over anhydrous MgSO 4, filtered, and concentrated under reduced pressure. The crude product was purified by flash chromatography (SiO 2 (120 g), n-hexane/etoac = 10/0 to 7/3) to give H 4 L2 (2) as a white solid in 60% yield. M.p. = 153 155 C; 1 H NMR (500 MHz, CDCl 3, 25 C, 5.7 mm) δ 7.84 (m, 2H, ArH), 7.67 (dd, J = 6.9 Hz, 1.9 Hz, 2H, ArH), 7.56 7.61 (m, 4H, ArH), 7.40 (d, J = 2.5 Hz, 2H, ArH), 7.36 (dd, J = 8.5 Hz, 2.5 Hz, 2H, ArH), 7.31 7.34 (m, 4H, ArH), 7.00 (d, J = 8.5 Hz, 2H, ArH), 5.69 (s, 2H, OH), 5.59 (s, 2H, OH), 1.36 (s, 18H, t-bu), 1.34 (s, 18H, t-bu); ESI-MS (CH 3 CN, negative): m/z = 745 [M H] ; Anal. Calcd for C 52 H 58 O 4 : C, 83.61; H, 7.83. Found: C, 83.62; H, 7.83. 4. NMR Data of the Helicates (±)-DH2 BNaB Na + : 1 H NMR (500 MHz, acetone-d 6, 25 C, 0.9 mm) δ 7.55 (dd, J = 7.7 Hz, 7.7 Hz, 4H, ArH), 7.41 7.49 (m, 8H, ArH), 7.30 (d, J = 2.7 Hz, 4H, ArH), 6.97 (br t, 4H, ArH), 6.92 (d, J = 2.7 Hz, 4H, ArH), 6.78 (d, J = 2.5 Hz, 4H, ArH), 6.34 (dd, J = 8.3 Hz, 2.5 Hz, 4H, ArH), 5.49 (d, J = 8.3 Hz, 4H, ArH), 1.35 (s, 36H, t-bu), 0.93 (s, 36H, t-bu); 13 C nature chemistry www.nature.com/naturechemistry 3

supplementary information NMR (125 MHz, acetone-d 6, 25 C, 2.8 mm) δ 153.3, 151.2, 143.0, 142.3, 141.4, 141.3, 134.1, 134.0, 130.6, 130.0, 129.2, 128.8, 128.0, 126.8, 125.8, 125.5, 124.9, 120.5, 34.6, 34.1, 32.0, 31.8. (±)-DH2 BNaB BMAmm + : H NMR (500 MHz, CD 3 CN, 25 C) δ 7.44 7.60 (m, 17H, ArH), 7.27 (d, J = 2.7 Hz, 4H, ArH), 6.90 (d, J = 2.7 Hz, 4H, ArH), 6.74 (d, J = 2.5 Hz, 4H, ArH), 6.41 (br t, 4H, ArH), 6.29 (dd, J = 8.3 Hz, 2.5 Hz, 4H, ArH), 5.32 (d, J = 8.2 Hz, 4H, ArH), 4.36 (s, 2H, CH 2 N), 2.98 (s, 12H, NCH 3 ), 1.30 (s, 36H, t-bu), 0.84 (s, 36H, t-bu). (+)-DH2 BNaB ( )-DMEph + : 1 H NMR (500 MHz, CD 2 Cl 2, 25 C, 0.8 mm) δ 7.37-7.45 (m, 9H, ArH), 7.30-7.35 (m, 2H, ArH), 7.22 (d, J = 2.6 Hz, 4H, ArH), 7.12-7.18 (m, 4H, ArH), 6.94 (d, J = 2.5 Hz, 4H, ArH), 6.87 (d, J = 7.3 Hz, 2H), 6.80 (d, J = 2.6 Hz, 4H, ArH), 6.29 (br t, 4H, ArH), 6.27 (dd, J = 8.3 Hz, 2.6 Hz, 4H, ArH), 5.56 (d, J = 4.8 Hz, 1H, CHOH), 5.28-5.35 (m, 4H, ArH), 4.71 (d, J = 4.8 Hz, 1H, OH), 2.78-2.89 (m, 2H, CH 2 N), 2.65-2.73 (m, 1H, CHCH 3 ), 2.59 (s, 3H, CH 3 N), 2.47 (s, 3H, CH 3 N), 1.32 (s, 36H, t-bu), 0.86-1.30 (m, 26H, CHCH 3, (CH 2 ) 10 CH 3 ), 0.83 (s, 36H, t-bu). (+)-DH2 BNaB TBAmm + (93% e.e.): 1 H NMR (500 MHz, CD 2 Cl 2, 25 C, 0.6 mm) δ 7.50-7.54 (m, 4H, ArH), 7.43-7.48 (m, 8H, ArH), 7.27 (d, J = 2.6 Hz, 4H, ArH), 6.94 (d, J = 2.7 Hz, 4H, ArH), 6.81 (d, J = 2.6 Hz, 4H, ArH), 6.42 (br t, 4H, ArH), 6.30 (dd, J = 8.3 Hz, 2.6 Hz, 4H, ArH), 5.40 (d, J = 8.3 Hz, 4H, ArH), 2.72-2.85 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 1.31 (s, 36H, t-bu), 1.17-1.29 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 0.96-1.11 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 0.85 (s, 36H, t-bu), 0.77 (t, J = 7.3 Hz, 12H, NCH 2 CH 2 CH 2 CH 3 ). 1 H NMR (500 MHz, CD 3 CN, 25 C, 0.3 mm) δ 7.46-7.58 (m, 12H, ArH), 7.27 (d, J = 2.6 Hz, 4H, ArH), 6.90 (d, J = 2.6 Hz, 4H, ArH), 6.73 (d, J = 2.5 Hz, 4H, ArH), 6.41 (br t, 4H, ArH), 6.28 (dd, J = 8.3 Hz, 2.5 Hz, 4H, ArH), 5.32 (d, J =8.3 Hz, 4H, ArH), 3.03-3.10 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 1.55-1.63 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 1.31-1.40 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 1.31 (s, 36H, t-bu), 0.96 (t, J = 7.3 Hz 12H, NCH 2 CH 2 CH 2 CH 3 ), 0.84 (s, 36H, t-bu). (+)-DH2 BB 2 TBAmm + Na + 221: 1 H NMR (500 MHz, CD 3 CN, 25 C, 0.3 mm) δ 7.53 (d, J = 8.0 Hz, 4H, ArH), 7.43 (d, J = 2.7 Hz, 4H, ArH), 7.41 (d, J = 2.5 Hz, 4H, ArH), 7.17 (d, J = 2.5 Hz, 4H, ArH), 7.16 (dd, J = 8.2 Hz, 2.1 Hz, 4H, ArH), 7.07-7.11 (m, 8H, ArH), 6.68 (t, J = 7.7 Hz, 4H, ArH), 6.55 (d, J = 8.4 Hz, 4H, ArH), 3.46-3.67 (m, 20H, 221), 3.03-3.09 (m, 4 nature chemistry www.nature.com/naturechemistry

supplementary information 8H, NCH 2 CH 2 CH 2 CH 3 ), 2.50-2.65 (m, 12H, 221), 1.54-1.63 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 1.45 (s, 36H, t-bu), 1.36 (s, 36H, t-bu), 1.30-1.38 (m, 8H, NCH 2 CH 2 CH 2 CH 3 ), 0.96 (t, J = 7.3 Hz, 12H, NCH 2 CH 2 CH 2 CH 3 ). nature chemistry www.nature.com/naturechemistry 5

supplementary information X-ray Crystallographic Data of (±)-DH2 BNaB BMAmm + X-ray diffraction data for (±)-DH2 BNaB BMAmm + were collected on a Bruker Smart Apex CCD-based X-ray diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 153 K. Single crystals of (±)-DH2 BNaB BMAmm + [C 126 H 142 B 2 N 7 NaO 8, MW = 1927.8] suitable for X-ray analysis were grown by slow evaporation of an CH 3 CN solution, and a single colorless crystal with dimensions 0.5 0.4 0.3 mm 3 was selected for intensity measurements. The unit cell was monoclinic with the space group P2 1 /c. Lattice constants with Z = 4, ρ calcd = 1.148 g cm 3, μ(mo Kα) = 0.074 mm 1, F(000) = 4128, 2θ max = 52.66 were a = 15.660(2) Å, b = 27.148(4), c = 26.357(4) Å, β = 95.726(3), and V = 11,151(3) Å 3. A total of 81,641 reflections was collected, of which 27,780 reflections were independent (R int = 0.0487). The structure was refined to final R 1 = 0.0677 for 19,203 data [I>2σ(I)] with 1,677 parameters and wr 2 = 0.2143 for all data, GOF = 1.044, and residual electron density max/min = 1.183/ 0.410 e Å 3. The ORTEP drawing is shown in Figure S1, and crystal data and structure refinement are listed in Table S1. Data collection, indexing, and initial cell refinements were carried out using the program SMART 3. Frame integration and final cell refinements were performed using SAINT software 4. A multiple absorption correction for each data set was applied using the program SADABS 5. The structure was solved by direct methods and Fourier techniques using the program SIR-97 6 and refined by full-matrix least squares methods on F 2 using SHELXL-97 7 incorporated in SHELXTL-PC 8. All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were calculated geometrically and refined using the riding models. Some t-butyl groups showed high Ueq(max)/Ueq(min) ratios for C atoms. We tried to resolve these problems by assigning alternative positions with partial occupancies for the t-butyl groups, but some of the atoms continue to have the high Ueq(max)/Ueq(min) ratios, which are indicative of the dynamic nature of the disorder in these t-butyl groups. 6 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S1. ORTEP drawing of the crystal structure of (±)-DH2 BNaB BMAmm + with thermal ellipsoids at 50% probability. nature chemistry www.nature.com/naturechemistry 7

supplementary information Table S1. Crystal data and structure refinement for (±)-DH2 BNaB BMAmm + Empirical formula (C 114 H 124 B 2 NNaO 8 ) (C 2 H 3 N) 6 Formula weight 1927.8 Temperature 153 K Wavelength 0.71073 Å Crystal system Monoclinic Space group P2 1 /c Unit cell dimensions a = 15.661(2) Å α = 90. b = 27.148(4) Å β = 95.726(3). c = 26.357(4) Å γ = 90. Volume 11,151(3) Å 3 Z 4 Density (calculated) 1.148 g cm 3 Absorption coefficient 0.074 mm 1 F(000) 4,128 Crystal size 0.50 0.40 0.30 mm 3 Theta range for data collection 1.08 to 28.35 Index ranges 20 h 20, 36 k 28, 35 l 35 Reflections collected 81,641 Independent reflections 27,780 [R int = 0.0487] Completeness to theta 99.7% Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9781 and 0.9639 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 27,780 / 0 / 1,677 Goodness-of-fit on F 2 1.044 Final R indices [I>2σ(I)] R 1 = 0.0677, wr 2 = 0.1871 R indices (all data) R 1 = 0.1006, wr 2 = 0.2143 Largest diff. peak and hole 1.183 and 0.410 e Å 3 CCDC reference number CCDC-747666 8 nature chemistry www.nature.com/naturechemistry

supplementary information ESI-MS Spectra of DH2 BNaB Na + Figure S2. Negative mode ESI mass spectra of DH2 BNaB Na + in CH 3 CN. nature chemistry www.nature.com/naturechemistry 9

supplementary information gcosy Spectrum of DH2 BNaB Na + Figure S3. 500 MHz gcosy spectrum of DH2 BNaB Na + (acetone-d 6, 25 C, 3.7 mm). 10 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S4. Partial 500 MHz gcosy spectrum of DH2 BNaB Na + (acetone-d 6, 25 C, 3.7 mm). nature chemistry www.nature.com/naturechemistry 11

supplementary information NOESY Spectrum of DH2 BNaB Na + Figure S5. 500 MHz NOESY spectrum of DH2 BNaB Na + (acetone-d 6, 25 C, 3.7 mm, mixing time = 0.5 s). 12 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S6. Partial 500 MHz NOESY spectrum of DH2 BNaB Na + (acetone-d 6, 25 C, 3.7 mm, mixing time = 0.5 s). nature chemistry www.nature.com/naturechemistry 13

supplementary information Figure S7. Partial 500 MHz NOESY spectrum of DH2 BNaB Na + (acetone-d 6, 25 C, 3.7 mm, mixing time = 0.5 s). 14 nature chemistry www.nature.com/naturechemistry

supplementary information CD and UV/Vis Spectra of (+)-DH2 BNaB DMEph +, ( )-DH2 BNaB DMEph +, and (+)-DH2 BNaB TBAmm + Figure S8. CD and UV/Vis spectra (CH 3 CN, 25 C) of (+)-DH2 BNaB DMEph + (93% d.e.) (blue), ( )-DH2 BNaB DMEph + (29% d.e.) (red), and (+)-DH2 BNaB TBAmm + (93% e.e.) (dashed light blue). nature chemistry www.nature.com/naturechemistry 15

supplementary information Determination of the Diastereomeric Excess by NMR spectroscopy Figure S9. 500 MHz 1 H NMR spectra (CD 2 Cl 2, 25 C) of (a) the filtrate (( )-DH2 BNaB DMEph + (29% d.e.)) + ( )-DMEph + Br (ca. 9 eq) and (b) the precipitate ((+)-DH2 BNaB DMEph + (93% d.e.)). 16 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S10. Partial 500 MHz 1 H NMR spectra (CD 2 Cl 2, 25 C) of (a) the filtrate (( )-DH2 BNaB DMEph + (29% d.e.)) + ( )-DMEph + Br (ca. 9 eq) and (b) the precipitate ((+)-DH2 BNaB DMEph + (93% d.e.)). The d.e. of the filtrate was determined based on its relative CD intensity at 313 nm to that of the precipitate. nature chemistry www.nature.com/naturechemistry 17

supplementary information Replacement of the Chiral Cation of (+)-DH2 BNaB DMEph + with an Achiral Cation Figure S11. 500 MHz 1 H NMR spectra (CD 2 Cl 2, 25 C) of (a) (+)-DH2 BNaB DMEph + (93% d.e.) and (b) the corresponding enantiomeric (+)-DH2 BNaB TBAmm + (93% e.e.) after replacement of ( )-DMEph + with achiral TBAmm +. 18 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S12. Partial 500 MHz 1 H NMR spectra (CD 2 Cl 2, 25 C) of (a) (+)-DH2 BNaB DMEph + (93% d.e.) and (b) the corresponding enantiomeric (+)-DH2 BNaB TBAmm + (93% e.e.) after replacement of ( )-DMEph + with achiral TBAmm +. nature chemistry www.nature.com/naturechemistry 19

supplementary information X-ray Crystallographic Data of DH2 BB 2 (BMAmm + ) 2 X-ray diffraction data for (±)-DH2 BB 2 (BMAmm + ) 2 were collected on a Bruker Smart Apex CCD-based X-ray diffractometer with Mo-Kα radiation (λ = 0.71073 Å) at 153 K. Single crystals of (±)-DH2 BB 2 (BMAmm + ) 2 [(C 124 H 140 B 2 N 2 O 8 ) (C 2 N), MW = 1846.03] suitable for X-ray analysis were grown by slow evaporation of an CH 3 CN solution, and a single colorless crystal with dimensions 0.8 0.5 0.2 mm 3 was selected for intensity measurements. The unit cell was orthorhombic with the space group Pcc2. Lattice constants with Z = 4, ρ calcd = 1.012 g cm 3, μ(mo Kα) = 0.062 mm 1, F(000) = 3,964, 2θ max = 44.76 were a = 15.130(3) Å, b = 25.587(4), c = 31.300(6) Å,, and V = 12,118(4) Å 3. A total of 85,762 reflections was collected, of which 27,659 reflections were independent (R int = 0.0684). The structure was refined to final R 1 = 0.1037 for 16,428 data [I>2σ(I)] with 1,280 parameters and wr 2 = 0.3175 for all data, GOF = 1.057, and residual electron density max/min = 0.908/ 0.342 e Å 3. The ORTEP drawing is shown in Figure S13, and crystal data and structure refinement are listed in Table S2. Data collection, indexing, and initial cell refinements were carried out using the program SMART 3. Frame integration and final cell refinements were performed using SAINT software 4. A multiple absorption correction for each data set was applied using the program SADABS 5. The structure was solved by direct methods and Fourier techniques using the program SIR-97 6 and refined by full-matrix least squares methods on F 2 using SHELXL-97 7 incorporated in SHELXTL-PC 8. All non-hydrogen atoms were refined anisotropically. All hydrogen atoms were calculated geometrically and refined using the riding models. Some t-butyl groups showed high Ueq(max)/Ueq(min) and ADP ratios for C atoms. We tried to resolve these problems by assigning alternative positions with partial occupancies for the t-butyl groups, but some of the atoms continue to have the high Ueq(max)/Ueq(min) and ADP ratios, which are indicative of the dynamic nature of the disorder in these t-butyl groups. In addition, the benzyl groups of the ammonium cation showed the disordered feature. We have tried to resolve it by assigning alternative positions for the C atoms, which did not work out, leaving a large solvent accessible void in the structure. This indicates the dynamic nature of the disorder in the ammonium cation moiety. 20 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S13. ORTEP drawing of the crystal structure of (±)-DH2 BB 2 (BMAmm + ) 2 with thermal ellipsoids at 50% probability. nature chemistry www.nature.com/naturechemistry 21

supplementary information Table S2. Crystal data and structure refinement for (±)-DH2 BB 2 (BMAmm + ) 2 Empirical formula (C 124 H 140 B 2 N 2 O 8 ) (C 2 N) Formula weight 1846.03 Temperature 153 K Wavelength 0.71073 Å Crystal system orthorhombic Space group Pcc2 Unit cell dimensions a = 15.130(3) Å α = 90. b = 25.587(4) Å β = 90. c = 31.300(6) Å γ = 90. Volume 12,118(4) Å 3 Z 4 Density (calculated) 1.012 g cm 3 Absorption coefficient 0.062 mm 1 F(000) 3,964 Crystal size 0.8 0.5 0.2 mm 3 Theta range for data collection 2.03 to 28.38 Index ranges 19 h 20, 34 k 28, 41 l 36 Reflections collected 85,762 Independent reflections 27,659 [R int = 0.0684] Completeness to theta 98.9% Absorption correction Semi-empirical from equivalents Max. and min. transmission 0.9878 and 0.9523 Refinement method Full-matrix least-squares on F 2 Data / restraints / parameters 27,659 / 1 / 1,280 Goodness-of-fit on F 2 1.057 Final R indices [I>2σ(I)] R 1 = 0.1037, wr 2 = 0.2745 R indices (all data) R 1 = 0.1612, wr 2 = 0.3175 Largest diff. peak and hole 0.908 and 0.342 e Å 3 CCDC reference number CCDC-747665 22 nature chemistry www.nature.com/naturechemistry

supplementary information Table S3. Selected bond distances, bond angles, and dihedral angles of the crystal structures of (±)-DH2 BNaB BMAmm + and (±)-DH2 BB 2 (BMAmm + ) 2 (±)-DH2 BNaB BMAmm + (±)-DH2 BB 2 (BMAmm + ) 2 bond distance (Å) bond angle ( ) (±)-2 BNaB 2 (±)-2 BB C a -O a -B 1 119.53 119.94 O 1 -B 1 1.459 1.438 C b -O b -B 1 121.11 125.26 O 2 -B 1 1.486 1.472 O 3 -B 2 -O 4 113.95 112.75 O a -B 1 1.447 1.474 O 3 -B 2 -O c 100.25 114.85 O b -B 1 1.494 1.490 O 3 -B 2 -O d 114.38 101.88 O 3 -B 2 1.490 1.490 O 4 -B 2 -O c 99.57 99.57 O 4 -B 2 1.448 1.474 O 4 -B 2 -O d 102.10 114.40 O c -B 2 1.478 1.472 O c -B 2 -O d 112.78 114.03 O d -B 2 1.462 1.438 C 3 -O 3 -B 2 121.11 125.26 O 2 -Na 2.393 - C 4 -O 4 -B 2 121.65 119.94 O b -Na 2.401 - C c -O c -B 2 122.35 119.50 O 3 -Na 2.390 - C d -O d -B 2 118.48 116.57 O c -Na 2.415 - dihedral angle ( ) B 1 -B 2 5.994 13.015 R 1 -R 2 42.24 46.68 bond angle ( ) R 2 -R 3 42.00 161.46 O 1 -B 1 -O 2 113.29 114.03 R 3 -R 4 32.79 128.62 O 1 -B 1 -O a 102.90 114.40 R 4 -R 5 54.91 140.11 O 1 -B 1 -O b 113.37 101.88 R 5 -R 6 41.01 38.08 O 2 -B 1 -O a 113.76 99.57 R a -R b 41.75 38.08 O 2 -B 1 -O b 100.60 114.85 R b -R c 53.61 140.11 O a -B 1 -O b 113.41 112.75 R c -R d 33.00 128.62 C 1 -O 1 -B 1 119.95 116.57 R d -R e 42.20 161.46 C 2 -O 2 -B 1 123.02 119.50 R e -R f 44.89 46.68 nature chemistry www.nature.com/naturechemistry 23

supplementary information gcosy Spectrum of DH2 BB 2 (Na + 221) 2 Figure S14. 500 MHz gcosy spectrum of DH2 BB 2 (Na + 221) 2 (CD 3 CN, 25 C, 0.7 mm). 24 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S15. Partial 500 MHz gcosy spectrum of DH2 BB 2 (Na + 221) 2 (CD 3 CN, 25 C, 0.7 mm). nature chemistry www.nature.com/naturechemistry 25

supplementary information ROESY Spectrum of DH2 BB 2 (Na + 221) 2 Figure S16. 500 MHz ROESY spectrum of DH2 BB 2 (Na + 221) 2 (CD 3 CN, 25 C, 0.7 mm, mixing time = 0.8 s). 26 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S17. Partial 500 MHz ROESY spectrum of DH2 BB 2 (Na + 221) 2 (CD 3 CN, 25 C, 0.7 mm, mixing time = 0.8 s). nature chemistry www.nature.com/naturechemistry 27

supplementary information Figure S18. Partial 500 MHz ROESY spectrum of DH2 BB 2 (Na + 221) 2 (CD 3 CN, 25 C, 0.7 mm, mixing time = 0.8 s). 28 nature chemistry www.nature.com/naturechemistry

supplementary information 1 H NMR Spectra of H 4 L2, DH2 BNaB Na +, and DH2 BB 2 (Na + 221) 2 Figure S19. Partial 500 MHz 1 H NMR spectra of H 4 L2 (red), DH2 BNaB Na + (blue), and DH2 BB 2 (Na + 221) 2 (green) (CD 3 CN, 25 C). nature chemistry www.nature.com/naturechemistry 29

supplementary information 1 H NMR Spectra of 221, Na + 221, and DH2 BB 2 (Na + 221) 2 Figure S20. 500 MHz DH2 BB 2 (Na + 221) 2 (black) (CD 3 CN, 25 C). 1 H NMR spectra of 221 (red), Na + 221 (blue), and 30 nature chemistry www.nature.com/naturechemistry

supplementary information Interconversion between (+)-DH2 BNaB TBAmm + using Na + ion and (+)-DH2 BB 2 TBAmm + Na + 221 Figure S21. 1 H NMR spectra of (a) (+)-DH2 BNaB TBAmm + (red), (b) (a) + 221 (1.5 eq) (blue), and (c) (b) + NaPF 6 (1.5 eq) (green) (CD 3 CN, 25 C, 0.28 mm). nature chemistry www.nature.com/naturechemistry 31

supplementary information Determination of the Binding Constant of (+)-DH2 BB 2 X 2+ to Na + ion The binding constant of (+)-DH2 BB 2 X 2+ to Na + ion was determined by the competitive binding titrations by use of dicyclohexano-18-crown-6 ether (DC18C6), since it is very high and beyond the detection limit of 1 H NMR spectroscopy. The competitive binding equilibrium between DH2 BB 2 X 2+ and DC18C6 is described as equation (1), DH2 BNaB X + + DC18C6 DH2 BB 2 X 2+ + Na + DC18C6, K rel = [DH2 BB 2 X 2+ ][Na + DC18C6]/([DH2 BNaB X + ][DC18C6]) = K C /K B (1) where K B and K C are the binding constants of DH2 BB 2 X 2+ and DC18C6 to Na + ion expressed by the following equations, (2) and (3), respectively. DH2 BB 2 X 2+ + Na + DH2 BNaB X +, K B = [DH2 BNaB X + ]/([DH2 BB 2 X 2+ ][Na + ]) (2) DC18C6 + Na + Na + DC18C6, K C = [Na + DC18C6]/([DC18C6][Na + ]) (3) Increasing amounts of DC18C6 were added into a solution of (+)-DH2 BNaB TBAmm + in CD 3 CN (4.60 10 4 M, 64% e.e.), and their 1 H NMR spectra were recorded at 25 C after each addition. The concentrations of (+)-DH2 BNaB and (+)-DH2 BB 2 were determined by the integral ratio of the signals, and plots of the concentration of DH2 2 BB versus the total amount of added DC18C6 gave a binding isotherm as shown in Figure S22. The data were fitted to the following equation by the least-squares curve-fitting methods: [DH2 2 BB ] = [(B 0 +C 0 ) {(B 0 +C 0 ) 2 4(1 1/K rel )B 0 C 0 } 1/2 ]/{2(1 1/K rel )} (4), where B 0 and C 0 are the initial concentration of (+)-DH2 BNaB and the total amount of added DC18C6, respectively. The competitive binding constant, K rel, was determined to be (7.94 ± 0.21) 10 2, from which the binding constant of the extended helicate, DH2 2 BB, to Na + ion was calculated at 2.68 10 6 M 1 in acetonitrile at 25 C by using the K C value of 2.13 10 5 M 1 in acetonitrile at 25 C reported by Buschmann. 9 32 nature chemistry www.nature.com/naturechemistry

supplementary information Figure S22. Plot of the concentration of DH2 BB 2 versus the total amount of added DC18C6 in the competitive binding titration. The red solid line represents the curve-fitting result. nature chemistry www.nature.com/naturechemistry 33

supplementary information Temperature Effect on CD and Absorption Spectra of (+)-DH2 BNaB and (+)-DH2 BB 2 Figure S23. CD and absorption spectra (CH 3 CN, 25 C, cell length = 1.0 mm) of (a) (+)-DH2 BNaB TBAmm + (0.056 mm, 64% e.e.) and (b) (+)-DH2 BB 2 TBAmm + Na + 221 (0.055 mm, 64% e.e.) at various temperatures. 34 nature chemistry www.nature.com/naturechemistry

supplementary information Interconversion between (+)-DH2 BNaB and (+)-DH2 BB 2 using Li + or K + ion Figure S24. CD and absorption spectral changes (CH 3 CN, 25 C, cell length = 0.2 mm) of (a) (+)-DH2 BNaB TBAmm + (0.28 mm, 64% e.e.) (i) before (blue) and (ii) after the addition of cryptand [2.2.1] (2.8 eq, red), and (iii) further addition of LiPF 6 (2.8 eq, dotted black) and (iv) cryptand [2.1.1] (green, 8.4 eq), and (b) (+)-DH2 BNaB TBAmm + (0.28 mm, 64% e.e.) (i) before (blue) and (ii) after the addition of cryptand [2.2.1] (3.0 eq, red), and (iii) further addition of KPF 6 (3.5 eq, dotted black) and (iv) cryptand [2.2.2] (green, 6.0 eq). nature chemistry www.nature.com/naturechemistry 35

supplementary information Stopped-Flow CD Measurements for the Extension and Contraction Events Figure S25. Time traces of the changes in CD and absorption intensities at 240 nm in the (a) extension and (b) contraction events of the helicates measured in acetonitrile at 22 C. Stopped-flow measurements were performed using a JASCO J-820 spectropolarimeter with an SFS-492 stopped-flow attachment. Solutions of (+)-DH2 BNaB TBAmm + (0.152 mm, 64% e.e.) and 221 (0.456 mm) (a), or (+)-DH2 BB 2 TBAmm + (Na + 221) (0.102 mm (prepared from 0.102 mm of (+)-DH2 BNaB TBAmm + (64% e.e.) and 0.153 mm of 221) and NaPF 6 (0.456 mm) (b) were loaded in 10-mL syringes equipped with the attachment. Same volumes (50 μl each) of the solutions were mixed at a flow rate of 5 ml/msec at 22 C, and the changes in the intensities of the CD and absorption at 240 nm were monitored. The data for the extension were fit to the equation (1) based on a pseudo-second order kinetics by the nonlinear least-squares curve-fitting method to yield a k ext of (5.38 ± 0.05) 10 3 M 1 s 1 (see the solid black line in Fig. S25a). CD = α[dh2 BNaB ] 0 + (γ α)([221] 0 ([221] 0 )exp{([221] 0 [DH2 BNaB ] 0 )kt})/(1 ([221] 0 /[DH2 BNaB ] 0 )exp{([221] 0 [DH2 BNaB ] 0 )kt}) eq. (1), where α and γ are the ellipticities per concentration of DH2 BNaB and DH2 2 BB, respectively. In contrast, the contraction event was too fast to follow under the present experimental conditions, indicating that the contraction might finish at least within the dead time of 7.8 msec. Given that the half-life time (τ) is shorter than 7.8 msec, the pseudo-second order rate 36 nature chemistry www.nature.com/naturechemistry

supplementary information constant for the contraction was estimated to be higher than a k cont of 4.8 10 5 M 1 s 1, according to the equation (2) derived from the equation (1). k = ln[(2[napf 6 ] 0 [DH2 BB 2 ] 0 )/[NaPF 6 ] 0 ]/{([NaPF 6 ] 0 [DH2 BB 2 ] 0 )τ} eq. (2) 4. Supporting References 1. Katagiri, H., Miyagawa, T., Furusho, Y. & Yashima, E. Synthesis and optical resolution of a double helicate consisting of ortho-linked hexaphenol strands bridged by spiroborates. Angew. Chem. Int. Ed. 45, 1741-174, (2006). 2. Demir, A. S., Reis, O. & Emrullahoglu, M. Role of copper species in the oxidative dimerization of arylboronic acids: Synthesis of symmetrical biaryls. J. Org. Chem. 68, 10130-10134 (2003). 3. Bruker. SMART Version 5.624: Program for collecting frames of data, indexing reflection, and determination of lattice parameters; Bruker AXS, Inc., Madison, Wisconsin, USA (2000). 4. Bruker, SAINT Version 6.02: Program for integration of the intensity of reflections and scaling; Bruker AXS, Inc., Madison, Wisconsin, USA (2000). 5. Sheldrick, G. M. SADABS Version 2.03: Program for Performing Absorption Corrections to Single-Crystal X-ray Diffraction Patterns; University of Göttingen, Göttingen, Germany (2001). 6. SIR-97: Program for Crystal Structure Solution. Altomare, A., Burla, M. C., Camalli, M., Cascarano, G. L., Giacovazzo, C., Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. J. Appl. Crystallogr. 32, 155 (1999). 7. Sheldrick, G. M. SHELXL-97: Program for the Refinement of Crystal Structures; University of Göttingen, Göttingen, Germany (1997). 8. Bruker, SHELXTL Version 5.10: Suite of Programs for Crystal Structure Analysis, Incorporating Structure Solution (XS), Least-Squares Refinement (XL), and Graphics (XP); Bruker AXS, Inc., Madison, Wisconsin, USA (2000). 9. Buschmann, H.-J. J. Solution Chem. 17, 277 286 (1988). nature chemistry www.nature.com/naturechemistry 37