A Dynamic and Responsive Host in Action: Light-Controlled Molecular

Supporting Information

A Dynamic and Responsive Host in Action: Light-Controlled Molecular Encapsulation Sen T. J. Ryan+, Jesffls del Barrio+,* Reynier Suardaz, Daniel F. Ryan, Edina Rosta, and Oren A. Scherman* anie_201607693_sm_miscellaneous_information.pdf

Contents 1 Materials and Methods

S4

1.1

Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

S4

1.2

Nuclear Magnetic Resonance (NMR) Spectroscopy . . . . . . . . . . . . . .

S4

1.3

Electronic Absorption (UV-vis) Spectroscopy . . . . . . . . . . . . . . . . .

S4

1.4

Computational Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . .

S4

1.5

Kinetic Data Fitting for Z→E Thermal Isomerisation . . . . . . . . . . . . .

S4

2 Synthesis

S6

2.1

Synthesis of 4,4’-[Bis(hydroxy)methyl]azobenzene (1)

. . . . . . . . . . . .

S6

2.2

4,4’-[Bis(imidazol-1-ylmethyl]azobenzene (2) . . . . . . . . . . . . . . . . . .

S6

2.3

1,1’-[1,2-phenylenebis(methylene)]bis[3-methyl-imidazolium dihexafluorophosphate (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S7

2.4

Synthesis of oAzoBox4+ ·4BF4 − . . . . . . . . . . . . . . . . . . . . . . . .

S7

2.5

Synthesis of

S8

AzoBI2+ ·2PF6 −

. . . . . . . . . . . . . . . . . . . . . . . . . .

3 Electronic Absorption Spectroscopy 3.1

Photoisomerisation of

AzoBI2+

3.2

Photoisomerisation of

oAzoBox4+

S9

. . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . S10

4 Nuclear Magnetic Resonance Spectroscopy 4.1

S11

Two-Dimensional NMR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S11 4.1.1 4.1.2

4.2

COSY 1 H NMR ROESY

1H

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . S11

NMR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S14

One-Dimensional NMR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S16

5 Kinetics and Thermodynamics of E →Z Thermal Isomerisation 5.1

5.2

S9

S21

Differential Equations for the thermal Z →E isomerisation of oAzoBox4+ . S21 5.1.1

oAzoBox4+ ·4BF4 − . . . . . . . . . . . . . . . . . . . . . . . . . . . . S22

5.1.2

AzoBI2+ ·2PF6 − . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S27

Additional Guests for oAzoBox4+ . . . . . . . . . . . . . . . . . . . . . . . S36

6 Electrospray Ionisation Mass Spectrometry

S36

7 X-ray Crystallography

S37

7.1

oAzoBox4+ ·4BF4 −

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S37

7.1.1

Crystallization Methods . . . . . . . . . . . . . . . . . . . . . . . . . S37

7.1.2

X-ray Crystallography . . . . . . . . . . . . . . . . . . . . . . . . . . S37

7.1.3

Crystallographic Data . . . . . . . . . . . . . . . . . . . . . . . . . . S37

8 Computational Studies

S38

8.1

Energy Minimised Structures of

8.2

Relaxed Potention Energy Surface Scans for Thermal Z →E Isomerisation of oAzoBox4+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S41

8.3

Energy Minimised Structures of oAzoBI2+ . . . . . . . . . . . . . . . . . . S42

oAzoBox4+

S2

. . . . . . . . . . . . . . . . . S38

9 Phototriggered Guest Release

S43

S3

1 1.1

Materials and Methods Materials

All materials and anhydrous solvents were purchased from Aldrich and used as received. 1 was synthesised by a previously reported literature procedure [1] . BPDC was produced by dissolving biphenyl-4,4’-dicarboxylic acid in MeCN followed buy the addition of five equivalents of triethylamine, in line with previously reported procedures [2]

1.2

Nuclear Magnetic Resonance (NMR) Spectroscopy

1H

NMR spectra were recorded on a Bruker Avance 500 TCI Cryoprobe Spectrometer. Chemical Shifts are recorded in ppm (δ) in CD3 CN (internal reference set to δ 1.94 ppm). 13 C NMR (126 MHz) spectra were recorded using a Bruker Avance III QNP Cryoprobe with simultaneous decoupling of 1 H nuclei and externally referenced to TMS set to 0 ppm. Titrations were performed by using stock solutions of host and guest to make up samples of desired concentrations. All spectra were recorded at 298 K unless otherwise stated.

1.3

Electronic Absorption (UV-vis) Spectroscopy

Electronic absorption spectroscopy was performed on a Varian Cary 4000 UV-vis spectrophotometer at 298 K.

1.4

Computational Calculations

Gas phase geometry optimisations of the complex, host and guest molecules were performed using B3LYP functional in combination with TZVP and including the Grimme’s D3 dispersion correction with Becke-Johnson damping [3] . Frequency calculations were performed at the same level of theory to obtain the thermostatistical corrections from energy to free energy in the rigid rotor/harmonic-oscillator approximation and including zero-pointvibrational energy in the gas phase at 298K and 1 atm (GT RRHO ). Solvation free energy was obtained at the same level of theory and using acetonitrile SMD continuum model (Gacet). Association free energy ∆Ga is then calculated as the sum of those contributions to the gas phase association energy ∆E [4] . ∆Ga = ∆E + ∆GT RRHO + ∆Gacet

(S1)

The ∆ symbol represents that the supramolecular approach ∆X=X(complex)-X(host)X(guest) have been used. For E,E -oAzoBox4+ ⊂4DPDO the calculated Gibbs energy of association is -4.06 kcal mol−1 , which is in accordance with our experimental association constant.

1.5

Kinetic Data Fitting for Z→E Thermal Isomerisation

The evolution of E,Z -oAzoBox4+ at a given temperature was determined from the integrated intensities of its corresponding Hα resonances in the 1 H NMR spectra. However, as the decay of these states depends on the decay of E,E -oAzoBox4+ , the first step was to characterise its decay. This was done by fitting the integrated intensities of its Hα resonance as a function of time with the following equation S2.

S4

A(t) = A0 e−2k1 t + C

(S2)

A0 is the initial concentration of E,E -oAzoBox4+ , k1 is its decay rate, t is time, and C is a constant representing the background noise of our detector. The model fitting throughout this work was conducted using the Levenberg-Marquardt algorithm (LMA). LMA is a least squares fitting algorithm - whereby the squares of the residuals between the data and the model are minimised - and is more robust than some other least squares fitting algorithms, e.g. the Gauss-Newton algorithm. However, LMA still only finds a local minimum in the solution space and so requires a sufficiently good guesses for the model parameters as initial input. We therefore visually compared each fit to the data and found them all to approximate the data well. The uncertainties of the derived fit parameters quoted in this study represent one standard deviation. Having determined the initial concentration and decay rate of E,E -oAzoBox4+ , the evolution of E,Z -oAzoBox4+ was then fit the following equation S3. ez

B ez (t) = (B0ez + K1 A0 )e−k2 t − K1 A0 e−2k1 t + C

(S3)

B0ez is the initial concentration of E,Z -oAzoBox4+ (where the E -Hα resonance was monitored), k2ez is the decay rate of E,Z -oAzoBox4+ , K1 = k1 /(2k1 − k2ez ), and other variables have the same meaning as in Equation S2. When fitting, A0 and k1 were fixed as the best fit values obtained when fitting the evolution of E,E -oAzoBox4+ with Equation S2. However, C was allowed to vary to account for any change in the noise of our detector between the E,E -oAzoBox4+ and E,Z -oAzoBox4+ measurements. Equation S3 was then fit for Z,E -oAzoBox4+ (where the Z -Hα resonance was monitored), which hence allowed us to obtain values for B0ze and k2ze . Finally the combined evolution of E,Z -oAzoBox4+ and Z,E -oAzoBox4+ resonances was found by taking the average of the k2ez and k2ze , which we defined as k2 . This process described was repeated for the E,E, E,Z, and Z,E isomers at different temperatures.

S5

2 2.1

Synthesis Synthesis of 4,4’-[Bis(hydroxy)methyl]azobenzene (1) HO N N

OH

4-nitrobenzyl alcohol (10.0 g, 65.3 mmol), NaOH (4.0 g, 100.0 mmol) and Zn (5.0g, 76.5 mmol) in CH3 OH (40.0 mL) and H2 O (10,0 mL) were heated at reflux for 2 h. The reaction liquor was then filtered while hot and the precipitate was washed with warm CH3 OH (20 mL). The CH3 OH was then distilled from the filtrate and the residual suspension was neutralised with 1M HCl. The resulting orange precipitate was collected by filtration and washed with copious amount of H2 O. The residual solid was recrystallised from methanol (3.0 g, 38%). 1H

NMR (500 MHz, (CD3 )2 SO, E -isomer) δ (ppm) = 7.86 (d, 4H, J = 8.5 Hz), 7.53 (d, 4H, J = 8.5 Hz), 5.37 (t, 2H J = 5.8 Hz), 4.60 (d, 4H, J = 5.8 Hz); 13 C NMR (126 MHz, (CD ) SO, E -isomer) δ (ppm) = 150.85, 146.26, 127.12, 122.35, 62.45. 3 2

2.2

4,4’-[Bis(imidazol-1-ylmethyl]azobenzene (2) N N

N N N

N

1 (1.0 g, 4.1 mmol) and 1,1’-carbonyldiimidazole (1.7 g, 10.5 mmol) in 1-methyl-2pyrrolidinone (20.0 mL) was heated at 170 ◦ C for 1 h. After cooling to RT, the reaction mixture was diluted with ethyl acetate (60.0 mL) and washed with H2 O (2 x 40.0 mL), brine (40.0 mL) and dried over MgSO4 . The organic phase was filtered and the solvent was distilled from the filtrate. The residual solid was recrystallised from ethanol (1.0 g, 71%). 1H

NMR (500 MHz, (CD3 )2 SO, E -isomer) δ (ppm) = 7.87 (d, 4H, J = 8.5 Hz), 7.57 (m, 2H), 7.26 (d, 4H, J = 8.5 Hz), 7.10 (m, 2H), 6.91 (m, 2H), 5.18 (s, 4H); 13 C NMR (126 MHz, (CD ) SO, E -isomer) δ (ppm) = 150.61, 143.92, 141.54, 130.23, 3 2 125.97, 122.81, 122.12, 52.35;

S6

2.3

1,1’-[1,2-phenylenebis(methylene)]bis[3-methyl-imidazolium dihexafluorophosphate (3) 2PF6+ N

N

N

+ N

α,α′-Dibromo-o-xylene (1.5 g, 5.68 mmol) and N-methylimidiazole (1.87 g, 22.7 mmol) in CH3 CN (60 mL) were heated at reflux for 24 h. Upon cooling to room temperature, the white precipitate was filtered, washed with CH2 Cl (30 mL) and dried in air. The solid was then dissolved in water to which a saturated aqueous solution of ammonium hexafluorophosphate was added. The resulting precipitate was filtered and washed with H2O (50 mL) and CH3 OH (50 mL) and dried in air (2.32 g, 3.97 mmol, 70%). 1H

NMR (500 MHz, CD3 CN) δ (ppm) = 8.32 (s, 2H), 7.56-7.51 (m, 2H), 7.38 (m, 2H), 7.32-7.27 (b, 4H, two overlapping peaks), 5.35 (s, 4H), 3.82 (s, 6H); 13 C NMR (126 MHz, CD CN) δ (ppm) = 137.8, 133.3, 131.8, 131.8, 125.7, 124.0, 51.3, 3 37.6; ESI-MS: m/z = 134.0838 [3 - 2PF6 − ]2+ , 413.1324 [3 - PF6 − ]+ ; found, 134.0842 [3 2PF6 − ]2+ , 413.1334 [3 - PF6 − ]+ .

2.4

Synthesis of oAzoBox4+ ·4BF4 −

N

N N

+N

4BF-

N N+

+N N+

N N N

N

α,α′-dibromo-o-xylene (135 mg, 0.51 mmol) in CH3 CN (60 mL) was added dropwise to 2 (175 mg, 0.51 mmol) in CH3 CN (80 mL) over 6 h at RT with stirring in darkness. The solution was heated at reflux for 48 h. Upon cooling to RT, the solvent was removed under reduced pressure via rotary evaporation. H2 O (80 mL) was added to the residue and sonicated for 10 minutes to give an orange suspension, which was subjected to centrifugation. AgBF4 (317 mg, 1.63 mmol) in H2 O (10 mL) was then added to the supernatant in the dark, resulting in the precipitation of AgBr. The suspension was subjected to centrifugation, after which the supernatant was set aside. The solid residue was then washed with H2 O (30 mL) and centrifuged to obtain the supernatant, which was combined with the previous supernatant. This procedure was repeated three times. The combined supernatant was stirred at room temperature in the light for 48 h, after which the H2 O was removed via freeze drying. CH3 CN (70 mL) was then added to the residue, which was then centrifuged and the supernatant filtered through a 13 mm 0.45 µm S7

PTFE syringe filter. The filtrate was then heated to reflux for 10 minutes. Upon cooling to RT in the dark, the solvent was removed via rotary evaporation and the residue dried in vacuo. The crude product was then purified via recrystallisation (slow vapour diffusion of i-Pr2 O into CH3 CN, 10 mM) to yield oAzoBox4+ ·4BF4 − (74 mg, 24%). 1H

NMR (500 MHz, CD3 CN) δ (ppm) = 8.48 (s, 4H), 7.81 (d, 8H, J = 8.4 Hz), 7.667.62 (m, 4H), 7.55-7.51 (m, 4H), 7.48 (d, 8H, J = 8.4 Hz), 7.14 (m, 4H), 7.10 (m, 4H), 5.39 (s, 8H), 5.21 (s, 8H); 13 C NMR (126 MHz, CD CN) δ (ppm) = 153.5, 137.4, 136.8, 133.1, 132.6, 131.9, 131.0, 3 124.4, 123.7, 123.4, 53.4, 51.4; ESI-MS: m/z = 223.1104 [oAzoBox4+ ·4BF4 − - 4BF4 − ]4+ , 326.4817 [oAzoBox4+ ·4BF4 − 3BF4 − ]3+ , 533.2243 [oAzoBox4+ ·4BF4 − - 2BF4 − ]2+ ; found, 223.1101 [oAzoBox4+ ·4BF4 − 4BF4 − ]4+ , 326.4812 [oAzoBox4+ ·4BF4 − - 3BF4 − ]3+ , 533.2240 [oAzoBox4+ ·4BF4 − 2BF4 − ]2+ .

2.5

Synthesis of AzoBI2+ ·2PF6 − 2PF-

+N

N+

N N N

N

2 (40 mg, 0.12 mmol) and MeI (497 mg, 3.5 mmol) in CH3 CN (15 mL) were heated at reflux for 24 h. Upon cooling to RT the precipitate was filtered, washed with cold CH2 Cl2 (3 x 15 mL) and dried in vacuo. The solid was then dissolve in H2 O (10 mL) to which a solution of saturated, aqueous ammonium hexfluorophosphate (0.5 mL) was added. The resulting precipitate was filtered, washed with H2 O (2 x 10 mL) and CH3 OH (1 x 5 mL) and dried in vacuo to yield AzoBI2+ ·2PF6 − (66.5 mg, 86%). 1H

NMR (500 MHz, CD3 CN) δ (ppm) = 8.49 (s, 2H), 7.94 (d, 4H, J = 8.5 Hz), 7.56 (d, 4H, J = 8.5 Hz), 7.40 (m, 2H), 7.37 (m, 2H), 5.41 (s, 4H), 3.83 (s, 6H); 13 C NMR (126 MHz, CD CN) δ (ppm) = 153.7, 138.0, 137.3, 130.7, 125.2, 124.3, 123.4, 3 53.3, 37.0. ESI-MS: m/z = 186.1026 [AzoBI2+ ·2PF6 − - 2PF6 − ]2+ , 517.1699 [AzoBI2+ ·2PF6 − PF6 − ]+ ; found, 186.1021 [AzoBI2+ ·2PF6 − - 2PF6 − ]2+ , 517.1684[AzoBI2+ ·PF6 − - PF6 − ]+ .

S8

3

Electronic Absorption Spectroscopy Photoisomerisation of AzoBI2+

3.1

0.7

0.7

a) E

0.6

Z

Absorption (a.u.)

Absorption (a.u.)

0.6 0.5 0.4 0.3 0.2

0.4 0.3 0.2

200

250

300

350

400

450

500

0

550

200

250

300

Wavelength (nm)

0.6

Z

Absorption (a.u.)

Absorption (a.u.)

c) E

0.5 0.4 0.3 0.2 0.1

450

500

550

d) Z

500

550

500

550

E

0.5 0.4 0.3 0.2 0.1

200

250

300

350

400

450

500

0

550

200

250

300

Wavelength (nm)

350

400

450

Wavelength (nm)

0.7

0.7

e) E

0.6

Z

Absorption (a.u.)

0.6

Absorption (a.u.)

400

0.7

0.6

0.5 0.4 0.3 0.2 0.1 0

350

Wavelength (nm)

0.7

0

E

0.1

0.1 0

b) Z

0.5

f) Z

E

0.5 0.4 0.3 0.2 0.1

200

250

300

350

400

450

500

0

550

200

250

300

Wavelength (nm)

350

400

450

Wavelength (nm) 0.5

0.5

Z

b) Z

E

c) E

Z

d) Z

E

e) E

Z

f) Z

E

0.4

0.4

0.3

0.3

0.2

0.2

0.1

0.1 0

20 40 60 80 100 0

Time (s)

20 40 60 80 100 0

Time (s)

20 40 60 80 100 0

Time (s)

20 40 60 80 100 0

Time (s)

20 40 60 80 100 0

Time (s)

Absorption (a.u.)

Absorption (a.u.)

a) E

20 40 60 80 100 120

Time (s)

Figure S1. Electronic absorption spectra of AzoBI2+ (CH3 CN) upon increased irradiation at 350 nm to achieve the Z -photostationary state (a, c and e) and at 420 nm to achieve the E -photostationary state (b, d and f ) (top) and the kinetic profiles of the E →Z photoisomerisation as monitored by the change in optical density at 320 nm (bottom).

S9

Photoisomerisation of oAzoBox4+ 1.0

1.0

Z

b) Z

0.8

Absorption (a.u.)

Absorption (a.u.)

a) E

0.6 0.4 0.2 0

250

300

350

400

450

500

0.6 0.4 0.2 0

550

250

300

0.8 0.6 0.4 0.2 0

250

300

350

400

450

500

d) Z

0.4 0.2

300

350

400

500

550

500

550

E

0.4 0.2

250

300

350

400

1.0

Z

0.6

250

550

450

Wavelength (nm)

0.8

0

500

0.6

0

550

Absorption (a.u.)

Absorption (a.u.)

e) E

450

0.8

Wavelength (nm) 1.0

400

1.0

Z Absorption (a.u.)

Absorption (a.u.)

c) E

350

Wavelength (nm)

Wavelength (nm) 1.0

E

0.8

450

500

E

0.6 0.4 0.2 0

550

f) Z

0.8

250

300

Wavelength (nm)

350

400

450

Wavelength (nm) 1.0

1.0

Absorption (a.u.)

0.9

a) E

Z

b) Z

E

c) E

Z

d) Z

E

e) E

Z

f) Z

E

0.9

0.8

0.8

0.7

0.7

0.6

0.6

0.5

0.5

0.4

0.4 0.3

0.3 0.2 0

Absorption (a.u.)

3.2

0.2

50 100 150 200 250

0 20 40 60 80 100 120 0

50 100 150 200 250

0 20 40 60 80 100 120 0

50 100 150 200 250

0 20 40 60 80 100 120 140

Time (s)

Time (s)

Time (s)

Time (s)

Time (s)

Time (s)

Figure S2. Electronic absorption spectra of oAzoBox4+ (CH3 CN) upon increased irradiation at 350 nm to achieve the Z -photostationary state (a, c and e) and at 420 nm to achieve the E -photostationary state (b, d and f ) (top) and the kinetic profiles of the E →Z photoisomerisation as monitored by the change in optical density at 320 nm (bottom).

S10

4

Nuclear Magnetic Resonance Spectroscopy

4.1

Two-Dimensional NMR COSY 1 H NMR

4.1.1

E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

+N

N N

Hδ

N

N

N N

Hθ

Hβ

Hι

+

N

Hη

N

Hι H θ Hα

+

Hη

+N

Hδ

4BF4-

Hγ

Hγ

Hζ H ε

E,E

Hδ-E,EHγ

Hγ

E,E

Hα-E,EHγ

E,E

Hε-E,EHγ Hζ-E,EHη

E,E E,E

Hι-E,EHη

Hη E,E

E,E

Hβ-E,EHγ

E,E

5.5

E,E

H θ- H η

E,E

Hδ- Hη

6.5 Hε

E,E

Hδ-E,EHζ

E,E

Hθ-E,EHι

7.0

E,E

Hε-E,EHζ

Hζ Hθ Hι

E,E

Hα-E,EHβ

Hβ

7.5 E,E

Hδ-E,EHε

Hα

8.0 8.5

Hδ

8.5

8.0

7.5

7.0

6.5

6.0

5.5

δ/ppm Figure S3. COSY 1 H NMR spectrum (CD3 CN, 500 MHz) of oAzoBox4+ .

S11

δ/ppm

6.0

E,E-oAzoBox4+ Hα Hβ

Hε Hζ

N

+N +

4BF4-

Hγ

N N

N

Hδ

N

Hθ

+

Hι

Hη

N

N

N N

+

N N

E,E E,Z

E,Z

Hα

E,E

Hα

E,Z

Hζ

Z,Z

H θ, Hζ

Z,Z

Z,Z Z,E

H θ, E,Z Hθ E,E Hβ

Z,Z

Hβ

Hε Hβ , Z,E H ζ, E,Z Hε E,E Hζ Z,E

Hα

Hε, Hε

E,E

Z,Z

Hα Z,E

Hα

Z,E

Hβ-Z,EHα

Z,Z

Hβ-Z,ZHα Z,E

Z,E

E,Z

Hζ-Z,EHε

E,Z

Hζ- Hε

E,E

Hζ-E,EHε

Hι-Z,ZHθ Z,E Hι-Z,EHθ E,Z Hι-E,ZHθ

7.4

Hα-E,EHβ

Z,Z

Hε-Z,ZHζ

7.6

E,E

7.2

Z,Z

E,E

Hα-E,ZHβ

Hθ-E,EHι

7.8

E,Z

8.5

Hβ, Hε, E,E Z,E Hε H ζ, E,E E,Z Hζ Hε Z,Z ε H Z,Z Hβ Z,Z H θ, Z,Z E,Z Hζ Hζ Z,E Hθ , E,Z E,E Hθ Hβ E,E Hθ, E,Z Hβ, Z,Z Hι Z,E Hι, E,E Hι E,Z Hι E,E Hα

δ/ppm

Hα

7.0

Z,Z

Z,E

Z,E

6.8

Z,E

Hβ, Z,E Hι, E,Z Hι E,E Hι

Hθ, Z,Z Hι

E,Z

Hα

8.5

7.8

7.6

7.4

7.2

7.0

6.8

δ/ppm

, Figure S4. COSY 1 H NMR spectrum (CD3 CN, 500 MHz, aromatic-aromatic resonance correlation) of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm.

S12

E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

+N

4BF4-

Hγ

N N

Hδ

N

Hθ

+

Hι

Hη

+N

N

N N

+

N N E,Z Hζ H θ, E,Z Hβ, Z,ZHι Z,EHθ, Z,E E,Z H ι, Hθ E,Z E,E Hι Hβ E,E

E,E

H δ, Hδ E,Z

Hα

Z,Z

Hδ

E,E

Hα

Z,E

Z,Z

Hα Z,E

Hα

E,E

Hι

E,Z

Hδ

Z,E Z,E

Hγ

H θ, Hζ

Z,Z

Z,E

Hδ-Z,EHγ

E,E

Hβ-E,EHγ

Z,E

Hα-Z,EHγ

Hβ-Z,EHγ

Z,E

Hε-Z,EHγ

Z,Z

Hβ-Z,ZHγ

5.1

Z,E

Z,Z

Hε Hβ, Z,EHε, Z,E Hζ, E,EHε Z,Z Hβ E,Z Hε E,E Hζ

Z,Z

Hγ

5.2

E,E

Hα-Z,ZHγ

Hα-E,EHγ

E,E

Hδ-E,EHγ Hδ-Z,ZHγ

Z,Z

Z,Z

Hγ

Hε-E,EHγ

Hθ-E,ZHη

E,Z

Hα-E,ZHη

E,Z

Hγ

Hδ-E,ZHγ Z,E Hδ-Z,EHη Z,Z Hδ-Z,ZHη E,Z Hδ-E,ZHη E,E Hδ-E,EHη

Hζ,Z,ZHθ-Z,ZHη

Z,Z

E,E

Hη

8.5

E,Z

Hβ-E,ZHη E,E

Hθ-E,EHη

8.0

5.4

Hη

Hη E,Z Hη

Z,Z

E,Z

Z,E

5.3

E,E E,Z

δ/ppm

Z,Z E,E

E,E E,Z

Hζ-E,ZHη

7.5

Hζ-E,EHη

7.0

δ/ppm Figure S5. COSY 1 H NMR spectrum (CD3 CN, 500 MHz, aromatic-aliphatic resonance correlation) of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm.

S13

4.1.2

ROESY 1 H NMR E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

+N +

4BF4-

Hγ

N N

Hδ

Hθ

+

N

Hι

Hη

N

N

N N

+

N N

E,Z

Hζ

E,E

Hθ, Hι

Z,Z E,Z

Hβ, Z,E Hι, E,Z Hι E,E Hι

E,E

Hα

E,Z

Hα

Z,Z

Hθ, Hζ

Z,Z

Z,E

H θ, E,Z Hθ E,E Hβ

Z,Z

Hε H β, Z,E H ζ, E,Z Hε E,E Hζ Z,E

Z,Z

Hβ

Z,E

Hα

Z,E

Hε, Hε

E,E

Z,Z

Hα Z,E

Z,Z

Hβ-Z,ZHα

Hβ-Z,ZHα

6.8

Z,Z Z,Z

Z,E

Hι-Z,EHθ Hι-E,ZHθ

E,Z

Hζ-E,ZHε

Hι-E,EHθ

E,E

Hβ-E,EHε

Z,Z

Hι-Z,ZHθ

7.2

E,E

7.0

E,Z

Hα-E,EHβ

7.4

E,E

Hα-E,ZHβ

7.6

E,Z

δ/ppm

Hα

Z,E

Hζ-E,EHθ

7.8

E,E

E,E

Hε-E,EHα

8.0

Hβ, Hε, E,E Z,E Hε H ζ, E,E E,Z Hζ Hε Z,Z ε H Z,Z Hβ Z,Z H θ, Z,Z E,Z Hζ Hζ Z,E Hθ , E,Z E,E Hθ Hβ E,E Hθ, E,Z Hβ, Z,Z Hι Z,E Hι, E,EHι E,Z Hι E,E Hα Z,E

Hα

E,Z

Hα

8.0

7.8

7.6

7.4

7.2

7.0

6.8

δ/ppm

Figure S6. ROESY 1 H NMR spectrum (CD3 CN, 500 MHz, aromatic-aromatic resonance correlation) of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm.

S14

E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

+N +

4BF4-

Hγ

N N

Hδ

N

Hθ

+

Hι

Hη

N

N

N N

+

N N

Z,E Z,Z Hε Hθ, Hθ, Z,Z E,Z H β θ H Z,Z Z,E Hι Z,E Z,Z Hβ, E,EHε, θ, H E,Z E,E H β, Hβ Z,ZHζ Z,EHζ, Hε Z,E Hι , E,Z E,Z Hε Hζ E,Z Hι E,E Hζ E,E Hι E,E

E,E Z,E

E,E

H δ, Hδ

Hα

E,Z

Hα

Z,Z

Hδ E,Z

Hδ

Z,Z

Hα Z,E

Hα

Z,E

Hγ Z,E

Hδ-Z,EHγ

Z,E

Hζ-Z,EHγ Z,Z Hε-Z,ZHγ

E,E

Hβ-E,EHγ

E,E

Hα-E,EHγ

Z,E

Hε-Z,EHγ Z,E

5.1

Z,E

Hα- Hγ

Z,Z

Hβ-Z,ZHγ

Z,E

Hα-Z,EHγ Hα-Z,ZHγ

Z,Z

Hγ E,E

Hδ-E,EHγ Hδ-Z,ZHγ

Hζ-E,ZHη Z,E Hθ-Z,EHη E,E Hη-E,EHη E,Z E,Z H β- Hη

Z,Z

Hγ

5.2

E,Z

Z,Z

Hδ-E,ZHγ

E,E

Hζ-E,EHγ

Z,E

Hζ-Z,EHη Hε-E,ZHγ

E,Z

E,Z

E,Z

Hγ

δ/ppm

E,E

5.3

E,Z

Hα-E,ZHη Z,Z

Z,E

Hη

Hδ-Z,ZHη E,E Hδ-E,EHη

Z,Z

Hη Hη

E,Z

Hα-Z,ZHη

Z,Z

Z,Z

Hζ-Z,ZHη Hθ-Z,ZHη E,E Hζ-E,EHη

Z,Z

E,E

Hη

E,E

Hα-E,EHη

8.5

E,E

E,E

Hι- Hη

8.0

7.5

5.4

7.0

δ/ppm Figure S7. ROESY 1 H NMR spectrum (CD3 CN, 500 MHz, aromatic-aliphatic resonance correlation) of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm.

S15

4.2

One-Dimensional NMR E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

N

+N +

4BF4-

Hγ N

Hδ

+

N

Hθ Hι

Hη

N

N

N N

+

N N

E,E

Hδ Hδ

Z,E Z,Z

Hδ E,Z

Hδ

8.60

8.58

8.56

8.54

8.52

8.50

8.48

8.46

8.44

8.42

8.40

δ/ppm

Figure S8. 1 H NMR spectrum (CD3 CN, 500 MHz, aromatic region between 8.4-8.6 ppm) with resonance assignments of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm.

S16

E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

+N +

4BF4-

Hγ

N N

Hδ

Hθ

+

N

Hι

Hη

N

+

N

N N

N N

E,E

H θ, Hι

Z,Z

Z,E

H β, Hζ, E,Z Hε

Z,Z

Hβ

E,E

Hβ

Z,E

Z,Z

Hθ, Hζ

E,Z

Hβ, Z,E H ι, E,Z Hι

E,E

Hα

E,Z

Hα

Z,Z E,Z

Hζ

Z,Z

Hε

7.8

7.6

Z,E

Hα

Z,E

Hε, Hε

Hθ , E,Z Hθ

Hι

Hα

Hζ

Z,E E,E

8.0

Z,Z

E,E

E,E

7.4

7.2

7.0

6.8

6.6

δ/ppm Figure S9. 1 H NMR spectrum (CD3 CN, 500 MHz, aromatic region between 6.6-8.0 ppm) with resonance assignments of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm. E,E-oAzoBox4+ Hα Hβ

Hε N

Hζ

N

+N +

4BF4-

Hγ

N N

Hδ

N

+

Hθ Hι

Hη

N

N

N N

Z,Z

Hη Hη

+

N N

E,Z

E,E

E,E

Hη

Z,Z Z,E

Hη

5.50

5.45

5.40

5.35

E,Z

Hγ

5.30

Hγ

Hγ Z,E

Hγ

5.25

5.20

5.15

5.10

5.05 5.00

δ/ppm Figure S10. 1 H NMR spectrum (CD3 CN, 500 MHz, aliphatic region between 5.0-5.0 ppm) with resonance assignments of oAzoBox4+ upon partial Z -conversion via irradiation at 350 nm. S17

f) E-PSS

e) Z-PSS

d) E-PSS

c) Z-PSS

b) E-PSS

a) Z-PSS

9.0

8.5

8.0

7.5

7.0 6.5 δ/ppm

6.0

5.5

5.0

4.5

Figure S11. 1 H NMR spectra (CD3 CN, 500 MHz) of oAzoBox4+ upon alternating irradiation at 350 nm to achieve the Z -PSS (a, c and e) and at 420 nm to achieve the E -PSS (b, d and f ). S18

Hφ

Increasing Concentration of EtOH

Hω

9.0

8.0

7.0 δ/ppm

6.0

5.0

Figure S12. 1 H NMR titration (CD3 CN, 500 MHz) of EtOH into E,E -oAzoBox4+ ⊂4DPDO. Blue dotted lines track the shifting proton resonances of 4DPDO and E,E -Hδ and the red lines indicate the non-shifted 4DPDO proton resonances. The green and orange spectra (CD3 CN, 500 MHz, top) are that of 4DPDO and E,E -oAzoBox4+ , respectively.

S19

Hω

O

Hφ

N

a)

N

Hφ

O Hω

Hω

b)

O N

N O

+N

Hφ

N

Hζ

Hω Hε

N

Hδ

2PF6N +

Hφ

HMe

N

Hβ Hζ Hε

Hδ

N Hγ

Hα

c)

Hζ +N

Hδ

Hε

N

2PF6N+

N

HMe

Hα

Hβ

Hα

Hβ Hζ Hε

N Hδ

N Hγ Hα

8.6

8.4

Hβ

8.2

8.0

7.8

7.6

7.4

δ/ppm

Figure S13. 1 H NMR (CD3 CN, 500 MHz) of (a) 4DPDO, (b) 1:1 E -AzoBI2+ :4DPDO and (c) E -AzoBI2+ .

Hω

a)

Hφ

O N

N

Hφ

O Hω

Hι

b) Hδ

+

Hθ

Hω

N

2PF6-

N

Hφ Hι

Hζ

Hθ&Hε

Hι

Hζ

Hθ&Hε

O

Hζ

N N

Hε

Hδ

N

+

N

Hφ

O Hω

c)

Hδ

Hι

+

Hθ

N

2PF6-

N

Hζ N Hε

8.4

8.2

8.0

N+

Hδ

7.8

7.6

7.4

7.2

δ/ppm

Figure S14. 1 H NMR (CD3 CN, 500 MHz) of (a) 4DPDO, (b) 1:1 3:4DPDO and (c) 3.

S20

5

Kinetics and Thermodynamics of E →Z Thermal Isomerisation Z,Z-oAzoBox4+

2κ1

E,Z-oAzoBox4+

κ2

E,E-oAzoBox4+

Figure S15. Scheme illustrating the thermal Z →E isomerization of oAzoBox4+ . As either of two azobenzene units may undergo the initial Z →E isomerization in Z,Z -oAzoBox4+ , its the observed decay of is twice that of the actual rate of thermal isomerization of its two azobenzene components (κ1 ). E,Z -oAzoBox4+ may be equivalently written as Z,E -oAzoBox4+ .

5.1

Differential Equations for the thermal Z →E isomerisation of oAzoBox4+ A(t) = A0 e−2κ1 t + C a κ1 κ1 B(t) = (B 0 + A0 )e−κ2 t − A0 e−2κ1 t + C b 2κ1 − κ2 2κ1 − κ2 dA(t) = A′ (t) = −2κ1 A(t) dt dB(t) = B ′ (t) = 2κ1 A(t) − κ2 B(t) dt κB T −∆H ‡ −∆S ‡ e RT e R κ= h ln

−∆S ‡ −∆H ‡ 1 κh · + = T κB R T R

(S4) (S5) (S6) (S7) (S8) (S9)

A(t) represents the concentration of Z,Z -oAzoBox4+ , B(t) represents the concentration of E,Z -oAzoBox4+ (which is equivalent to Z,E -oAzoBox4+ ). Ca and Cb are constants.

S21

5.1.1

oAzoBox4+ ·4BF4 −

313 K

Time

9

8

7 δ/ppm

5

6

Figure S16. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 313 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. 3.5

Integration (a.u.)

3 2.5 2 1.5 1 0.5

0

500

1000

1500

2000

2500

3000

3500

4000

Time (min)

Figure S17. Kinetic fit of selected Hα proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 313 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. The integrations of the proton resonances were fitted to equations S6 and S7. Table S1. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the Hα proton resonances belonging to E,E -oAzoBox4+ , E,Z -oAzoBox4+ and Z,Z -oAzoBox4+ as measured by 1 H NMR (CD3 CN, 500 MHz, 313 K)

a

Proton

Shift [δ, ppm]

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

E,Z -Hα

7.984

Z,Z -Hα

6.904

0.000539

16.6

1853.70

0.000639a

0.948

1564.95

Z,E -Hα

6.798

0.000597

3.41

1674.48

Fit of the total integration area of the Z,Z -Hα proton resonance, such that the obtained rate constant is

twice that of a single AB unit (2κ1 ).

S22

318 K

Time

9

8

7 δ/ppm

5

6

Figure S18. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 318 K) Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. 3.5

Integration (a.u.)

3 2.5 2 1.5 1 0.5 0

500

1000

1500

2000

2500

3000

3500

Time (min)

Figure S19. Kinetic fit of selected Hα proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 318 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. The integrations of the proton resonances were fitted to equations S6 and S7. Table S2. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the Hα proton resonances belonging to E,E -oAzoBox4+ , E,Z -oAzoBox4+ and Z,Z -oAzoBox4+ as measured by 1 H NMR (CD3 CN, 500 MHz, 318 K).

a

Proton

Shift [δ, ppm]

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

E,Z -Hα

7.984

0.001057

13.1

945.64

Z,Z -Hα

6.904

0.00115a

1.112

1564.95

Z,E -Hα

6.798

0.001051

2.49

951.31

Fit of the total integration area of the Z,Z -Hα proton resonance, such that the obtained rate constant is

twice that of a single AB unit (2κ1 ).

S23

323 K

Time

9

8

7 δ/ppm

6

5

Figure S20. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 323 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. 1.8 1.6

Integration (a.u.)

1.4 1.2 1 0.8 0.6 0.4 0.2

0

500

1000

1500

2000

2500

Time (min)

Figure S21. Kinetic fit of selected proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 323 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. The integrations of the proton resonances were fitted to equations S6 and S7. Table S3. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the Hα proton resonances belonging to E,E -oAzoBox4+ , E,Z -oAzoBox4+ and Z,Z -oAzoBox4+ as measured by 1 H NMR (CD3 CN, 500 MHz, 323 K).

a

Proton

Shift [δ, ppm]

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

E,Z -Hα

7.984

0.001871

21.6

534.41

Z,Z -Hα

6.904

0.00201a

3.826

497.51

Z,E -Hα

6.798

0.001897

7.51

527.12

Fit of the total integration area of the Z,Z -Hα proton resonance, such that the obtained rate constant is

twice that of a single AB unit (2κ1 ).

S24

328 K

Time

9

8

6

7 δ/ppm

5

Figure S22. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 328 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. 3

Integration (a.u.)

2.5

2

1.5

1

0.5 0

500

1000

1500

Time (min)

Figure S23. Kinetic fit of selected Hα proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 328 K) of Z -predominant oAzoBox4+ , obtained by irradiation at 350 nm. The integrations of the proton resonances were fitted to equations S6 and S7. Table S4. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the Hα proton resonances belonging to E,E -oAzoBox4+ , E,Z -oAzoBox4+ and Z,Z -oAzoBox4+ as measured by 1 H NMR (CD3 CN, 500 MHz, 328 K).

a

Proton

Shift [δ, ppm]

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

E,Z -Hα

7.984

0.003294

31.1

303.56

Z,Z -Hα

6.904

0.00350a

7.017

285.71

Z,E -Hα

6.798

0.003303

9.78

302.72

Fit of the total integration area of the Z,Z -Hα proton resonance, such that the obtained rate constant is

twice that of a single AB unit (2κ1 ).

S25

Erying Plot (κ1 )

-40.0 -40.2

ln(κh/κbΤ)

-40.4 -40.6 -40.8 -41.0 -41.2 -41.4 -41.6 3.05

3.10

3.15 -1

3.20

-3

1/T (K x10 ) Figure S24. Erying plot for the rate constants (κ1 ) of Z →E thermal isomerisation of Z,Z -oAzoBox4+ →E,Z -oAzoBox4+ measured at 313, 318, 323 and 328 K. The four values of κ1 were obtained as half the values of the rate constants for the decay of the Z,Z -Hα resonance (Tables S1-S4). Inset: Fitted equation with the values of the slope and intercept.

ln(κh/κbΤ)

Erying Plot (κ2 )

-39.4 -39.6 -39.8 -40.0 -40.2 -40.4 -40.6 -40.8 -41.0 -41.2

3.05

3.10

3.15 -1

3.20

-3

1/T (K x10 ) Figure S25. Erying plot for the rate constants (κ2 ) of Z →E thermal isomerisation of E,Z -oAzoBox4+ →E,E -oAzoBox4+ measured at 313, 318, 323 and 328 K. The four values of κ2 were obtained as the average values of the rate constants for the decays of the E,Z -Hα and Z,E -Hα resonances (Tables S1-S4). Inset: Fitted equation with the values of the slope and intercept.

S26

5.1.2

AzoBI2+ ·2PF6 −

313 K

9

8

7

6

5

4

δ/ppm Figure S26. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 313 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm.

S27

250 E

Hδ Hδ E Hα E Hβ Z Hα E Hε E Hζ Z Hζ E Hγ Z Hγ E HMe Z HMe

Integration (A.U.)

Z

200 150 100 50 0 0

500

1000

1500

2000

2500

3000

3500

Time (min) Figure S27. Kinetic fit of selected proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 313 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm. The integrations of the proton resonance were fitted to single time dependent exponential functions using DynamicsCentre2.3 software. Table S5. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the proton resonances belonging to E -AzoBI2+ and Z -AzoBI2+ as measured by 1 H NMR (CD3 CN, 500 MHz, 313 K) Proton E -Hδ

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

8.519

0.000483

1.341

2070.39

Z -Hδ

8.422

0.000461

1.281

2169.20

E -Hα

7.986

0.000471

0.675

2123.14

E -Hβ

7.587

0.000477

0.670

2096.44

E -Hǫ

6.942

0.000486

1.091

2057.61

E -Hζ

7.436

0.000480

1.130

2083.33

Z -Hζ

7.405

0.000474

1.206

2109.70

Z -Hα

7.372

0.000477

0.459

2096.44

E -Hγ

5.444

0.000473

0.582

2114.16

Z -Hγ

5.268

0.000470

0.600

2127.66

E -HM e

3.878

0.000477

0.344

2096.44

Z -HM e

3.851

0.000477

0.361

2096.44

–

0.000476a

6.225b

2103.41 ± 27.76c

Z -AzoBI2+ a

Shift [δ, ppm]

Calculated from the average of all fitted resonances of Z -AzoBI2+ . 2+

deviation of the rate constant (κ) for Z -AzoBI

.

c

b

Calculated from the standard

Average time constant calculated from the average of

all time constants (τ ) and error calculated from the standard deviation of the rate constant for Z -AzoBI2+ .

S28

318 K

Time

9

8

7

6

5

4

δ/ppm Figure S28. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 318 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm.

S29

300 E

Hδ Hδ E Hα E Hβ Z Hα E Hε E Hζ Z Hζ E Hγ Z Hγ E HMe Z HMe

Integration (A.U.)

250

Z

200 150 100 50 0 0

500

1000

1500

2000

2500

3000

3500

Time (min) Figure S29. Kinetic fit of selected proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 318 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm. The integrations of the proton resonance were fitted to single time dependent exponential functions using DynamicsCentre2.3 software. Table S6. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the proton resonances belonging to E -AzoBI2+ and Z -AzoBI2+ as measured by 1 H NMR (CD3 CN, 500 MHz, 318 K) Proton

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

E -Hδ

8.519

0.000888

1.382

1126.13

Z -Hδ

8.422

0.000868

1.332

1152.07

E -Hα

7.986

0.000879

0.714

1137.66

E -Hβ

7.587

0.000880

0.662

1136.36

E -Hǫ

6.942

0.000873

1.142

1145.48

E -Hζ

7.436

0.000885

1.328

1129.94

Z -Hζ

7.405

0.000887

1.255

1127.40

Z -Hα

7.372

0.000875

0.488

1142.86

E -Hγ

5.444

0.000876

0.720

1141.55

Z -Hγ

5.268

0.000882

0.630

1133.79

E -HM e

3.878

0.000897

0.413

1114.83

Z -HM e

3.851

0.000896

0.409

1116.07

–

0.000882a

8.49b

1133.68 ± 10.89c

Z -AzoBI2+ a

Shift [δ, ppm]

Calculated from the average of all fitted resonances of Z -AzoBI2+ . 2+

deviation of the rate constant (κ) for Z -AzoBI

.

c

b

Calculated from the standard

Average time constant calculated from the average of

all time constants (τ ) and error calculated from the standard deviation of the rate constant for Z -AzoBI2+ .

S30

323 K

Time

9

8

7

6 δ/ppm

5

4

Figure S30. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 323 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm.

S31

1800 1600

E

Hδ Hδ E Hα E Hβ Z Hα E Hε E Hζ Z Hζ E Hγ Z Hγ E HMe Z HMe

Integration (A.U.)

Z

1400 1200 1000 800 600 400 200 0 0

200

400

600

800

1000

1200

1400

1600

1800

2000

Time (min) Figure S31. Kinetic fit of selected proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 323 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm. The integrations of the proton resonance were fitted to single time dependent exponential functions using DynamicsCentre2.3 software.

Table S7. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the proton resonances belonging to E -AzoBI2+ and Z -AzoBI2+ as measured by 1 H NMR (CD3 CN, 500 MHz, 323 K) Proton

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

E -Hδ

8.519

0.00151

3.469

662.25

Z -Hδ

8.422

0.00157

3.288

636.94

E -Hα

7.986

0.00152

1.779

657.89

E -Hβ

7.587

0.00151

1.694

662.25

E -Hǫ

7.436

0.00149

2.774

671.14

E -Hζ

7.405

0.00149

3.013

671.14

Z -Hζ

7.372

0.00161

3.164

621.11

Z -Hα

6.942

0.00157

1.881

636.94

E -Hγ

5.444

0.00153

1.408

653.59

Z -Hγ

5.268

0.00157

1.357

636.94

E -HM e

3.878

0.00156

0.9895

641.03

Z -HM e

3.851

0.00158

0.8289

632.91

–

0.00154a

37.4b

648.68 ± 15.724c

Z -AzoBI2+ a

Shift [δ, ppm]

Calculated from the average of all fitted resonances of Z -AzoBI2+ . 2+

deviation of the decay rate constant for Z -AzoBI

.

c

b

Calculated from the standard

Average time constant calculated from the average

of all time constants (τ ) and error calculated from the standard deviation of the rate constant for Z -AzoBI2+ .

S32

328 K

Time

9

8

7

6

5

4

δ/ppm Figure S32. Temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 328 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm.

S33

2200 E

Hδ Hδ E Hα E Hβ Z Hα E Hε E Hζ Z Hζ E Hγ Z Hγ E HMe Z HMe

2000

Z

Integration (A.U.)

1800 1600 1400 1200 1000 800 600 400 200 0 0

500

Time (min)

1000

1500

Figure S33. Kinetic fit of selected proton resonances of the temporal 1 H NMR thermal relaxation spectra (CD3 CN, 500 MHz, 328 K) of Z -predominant AzoBI2+ , obtained by irradiation at 350 nm. The integrations of the proton resonance were fitted to single time dependent exponential functions using DynamicsCentre2.3 software. Table S8. Rate (κ, min−1 ) and time constants (τ , min) for the rise and decay of the proton resonances belonging to E -AzoBI2+ and Z -AzoBI2+ as measured by 1 H NMR (CD3 CN, 500 MHz, 328 K) Proton E -Hδ

Rate Constant [κ, min−1 ]

Error in κ [∆κ, min−1 x 10−6 ]

Time Constant [τ , min]

8.519

0.00260

7.612

384.62

Z -Hδ

8.422

0.00267

8.016

374.53

E -Hα

7.986

0.00260

3.857

384.62

E -Hβ

7.587

0.00261

4.096

383.14

E -Hǫ

6.942

0.00260

6.138

384.62

E -Hζ

7.436

0.00262

6.763

381.68

Z -Hζ

7.405

0.00276

6.654

362.32

Z -Hα

7.372

0.00266

3.907

375.94

E -Hγ

5.444

0.00261

3.669

383.14

Z -Hγ

5.268

0.00268

3.320

373.13

E -HM e

3.878

0.00266

2.064

375.94

Z -HM e

3.851

0.00273

2.072

366.30

–

0.00265a

51.316b

377.50 ± 7.2c

Z -AzoBI2+ a

Shift [δ, ppm]

Calculated from the average of all fitted resonances of Z -AzoBI2+ . 2+

c

b

Calculated from the standard

deviation of the rate constant (κ) for Z -AzoBI . Average time constant calculated from the average of all time constants (τ ) and error calculated from the standard deviation of the rate constant for Z -AzoBI2+ .

S34

Erying Plot -39.6 -39.8

ln(κh/κbΤ)

-40.0 -40.2 -40.4 -40.6 -40.8 -41.0 -41.2 3.05

3.10

3.15

3.20

1/T (K-1x103) Figure S34. Erying plot for the rate constants of Z →E thermal isomerisation of Z -AzoBI2+ →E -AzoBI2+ measured at 313, 318, 323 and 328 K. The four values of κ were obtained as the average values of the moduli of the rate constants for the rise or decay of all resonances (Tables S5-S8). Inset: Fitted equation with the values of the slope and intercept. 70

Percentage Composition

60 50 E,E-Hα E,Z-Hα Z,E-Hα Z,Z-Hα

40 30 20 10 0

0

0.5

1

1.5 Time (min x 103)

2

2.5

3

Figure S35. Plot of the percentage composition, monitored by 1 H NMR (Hα resonances) over time during the thermal Z →E isomerisation of Z -predominant oAzoBox4+ in the presence and absence of 4DPDO. The samples were kept at identical temperatures throughout the approximate three week time span of the experiment, which were monitored as fluctuating between 14◦ C and 20◦ C.

S35

5.2

Additional Guests for oAzoBox4+ a) E,E-Hδ

b)

9

8

7

6

5

δ/ppm

Figure S36. 1 H NMR spectra (CD3 CN, 500 MHz) of (a) oAzoBox4+ and (b) oAzoBox4+ and excess PPO.

a) E,E-Hδ

b)

c)

hν

d)

9

8

7

6

5

δ/ppm

Figure S37. 1 H NMR spectra (CD3 CN, 500 MHz) of (a) oAzoBox4+ , (b) oAzoBox4+ and excess BPDC (c) oAzoBox4+ and excess BPDC after exposure to UV light (350 nm) and (d) BPDC.

Electrospray Ionisation Mass Spectrometry 4+

3+

270.1253

]

oAzoBox4+.4BF4DPDO - 2BF4-

U

] [

oAzoBox4+.4BF4DPDO - 3BF4-

U

] [

oAzoBox4+.4BF4DPDO - 4BF4-

U

[ Relative Abundance %

6

2+

627.2542

389.1685

100 80

270.3760 627.7553

389.5026

60 626.7552

40 270.6267

389.8367

628.2565

388.8360

20 270.8773

390.1709

626.2564

628.7575

0 269 270 271 272 386 388 390 392 624 626 628 630 632

m/z

m/z

m/z

Figure S38. Partial ESI-MS spectrum of E,E -oAzoBox4+ ⊂4DPDO (CH3 CN).

S36

7

X-ray Crystallography

7.1 7.1.1

oAzoBox4+ ·4BF4 − Crystallization Methods

X-Ray quality crystals of oAzoBox4+ ·4BF4 − were grown by the slow diffusion of i -Pr2 O vapours into an MeCN solution of oAzoBox4+ ·4BF4 − . Crystals formed under ambient conditions at room temperature over a period of days and were seen to be single and free of defects by use of an optical microscope fitted with a crossed-polarizer. Crystals were removed from the mother liquor and protected from desolvation by submersion in paratone oil before being mounted using an appropriate MiTeGen tip and flash frozen under a continuous stream of N2 . 7.1.2

X-ray Crystallography

(a) oAzoBox4+ ·4BF4 − : Data were collected at 180 K on a Bruker D8-QUEST diffractometer equipped with an Incoatec IµS Cu microsource (λ = 1.5418 Å) and PHOTON-100 CMOS detector. The data were collected and processed using APEX2, and a multi-scan correction was applied using SADABS [5] . All crystallographic data are available free of charge from the Cambridge Crystallographic Data Centre (CCDC) via www.ccdc.cam.ac.uk/data_request/cif. 7.1.3

Crystallographic Data

The crystallographic information, structural parameters and additional refinement details for oAzoBox4+ ·4BF4 − is given below. (a) oAzoBox4+ ·4BF4 − : C68 H64 B4 F16 N16 ; orange block, 0.260 x 0.120 x 0.080 mm3 ; triclinic, space group P21 /c; a = 20.5508(7), b = 9.5608(3), c = 19.40296(6) Å; α = 90, β = 116.996(2), γ = 90◦ ; V = 3396.9(2) Å3 ; Z = 2; ρcalcd = 1.373 Mg m−3 ; 2θ max = 100.864◦ ; T = 180(2) K; 19951 reflections collected, 3350 independent. µ = 0.983 mm−1 ; Rint = 0.0312; R1 = 0.0800 [I > 2.0σ(I)], wR2 = 0.2636 (all data); CCDC deposition number 1497573.

S37

8 8.1

Computational Studies Energy Minimised Structures of oAzoBox4+

Figure S39. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of E,Z -oAzoBox4+ .

Figure S40. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of Z,Z -oAzoBox4+ .

ΔE (kcal/mol)

ΔG‡ = 19.23 kcal/mol

Z,Z-oAzoBox4+ 25.90 kcal mol-1 ΔG‡ = 22.24 kcal/mol

E,Z-oAzoBox4+ 14.43 kcal mol-1

E,E-oAzoBox4+ 0 kcal mol-1

U

E,E-oAzoBox4+ DPDO -438.94 kcal mol-1

Figure S41. Structures, relative energies and thermal Z →E isomerisation activation energies of the three stereoisomers of oAzoBox4+ and E,E -oAzoBox4+ ⊂4DPDO. The energy is measured in kcal mol−1 and are compared to the lowest energy conformation of E,E -oAzoBox4+ , which is set to 0 kcal mol−1 . The energy of E,E -oAzoBox4+ ⊂4DPDO was calculated by taking the ground state energy of uncomplexed 4DPDO into account.

S38

Figure S42. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of E,E -oAzoBox4+ ⊂4DPDO revealing hydrogen bonding (dashed lines) between the Hδ resonances of E,E -oAzoBox4+ and the oxygen atoms of 4DPDO.

Figure S43. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of E,Z -oAzoBox4+ ⊂4DPDO.

Figure S44. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of Z,Z -oAzoBox4+ ⊂4DPDO.

S39

ΔE (kcal/mol)

U

Z,Z-oAzoBox4+ DPDO 51.98 kcal mol-1

U

E,Z-oAzoBox4+ DPDO 20.65 kcal mol-1

U

E,E-oAzoBox4+ DPDO 0 kcal mol-1

Figure S45. Structures, relative energies and thermal Z →E isomerisation activation energies of the three stereoisomers of oAzoBox4+ and E,E -oAzoBox4+ ⊂4DPDO. The energy is measured in kcal mol−1 and are compared to the lowest energy conformation of E,E -oAzoBox4+ , which is set to 0 kcal mol−1 . The energy of E,E -oAzoBox4+ ⊂4DPDO was calculated by taking the ground state energy of uncomplexed 4DPDO into account.

Figure S46. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of E,E -oAzoBox4+ ⊂BPDC.

S40

8.2

Relaxed Potention Energy Surface Scans for Thermal Z →E Isomerisation of oAzoBox4+

Table S9. Tabulated data for the relaxed potential energy surface scan around the C-N=N-C- azo torsion angle from Z,Z -oAzoBox4+ to E,Z -oAzoBox4+ .

Torsion Angle 13

Energy (a.u.) -2822.17396

Energy (kcal mol−1 ) -1770922.62

∆E (kcal mol−1 ) 0.000

43

-2822.166459

-1770917.92

4.702

73

-2822.143842

-1770903.73

18.90

103

-2822.137727

-1770899.89

22.73

133

-2822.172238

-1770921.55

1.08

163

-2822.191908

-1770933.89

-11.26

193

-2822.187292

-1770930.99

-8.37

Table S10. Tabulated data for the relaxed potential energy surface scan around the C-N=N-C- azo torsion angle from E,Z -oAzoBox4+ to E,E -oAzoBox4+ .

Torsion Angle 12

Energy (a.u.) -2822.19222

Energy (kcal mol−1 ) -1770934.08

∆E (kcal mol−1 ) 0.00

42

-2822.18502

-1770929.57

4.52

72

-2822.16408

-1770916.43

17.66

102

-2822.15748

-1770912.29

21.80

132

-2822.19621

-1770936.59

-2.50

162

-2822.21995

-1770951.49

-17.40

192

-2822.219099

-1770950.95

-16.87

S41

8.3

Energy Minimised Structures of oAzoBI2+

Figure S47. Geometry-optimised molecular structure (B3LYP-D3(BJ)/TZVP level of theory) of E -AzoBI2+ .

ΔE (kcal/mol)

Figure S48. Geometry-optimised molecular structure (B3LYP-D3/TZV level of theory) of Z -AzoBI2+ .

Z-AzoBI2+ 17.30 kcal mol-1

E-AzoBI2+ 0 kcal mol-1

Figure S49. Structures and relative energies the two stereoisomers of oAzoBI2+ . The energy is measured in kcal mol−1 and are compared to the lowest energy conformation of E -oAzoBII+ , which is set to 0 kcal mol−1 .

S42

9

Phototriggered Guest Release

Hω Hφ

Increasing Irradiation Time (350 nm)

E,E-Hδ

9.0

8.0

7.0 δ/ppm

6.0

5.0

Figure S50. 1 H NMR spectra (CD3 CN, 500 MHz) of E,E -oAzoBox4+ ⊂4DPDO upon increasingly longer exposure to UV light (350 nm). Blue dotted lines track the shifting proton resonances of 4DPDO and E,E -Hδ and the red lines indicate the non-shifted 4DPDO proton resonances. The upfield shift of the 4DPDO protons indicates release from the E,E -oAzoBox4+ cavity as a result of hydrogen bonding competition. The green and orange 1 H NMR spectra (CD3 CN, 500 MHz, top) are that of 4DPDO and E,E -oAzoBox4+ , respectively.

S43

Hφ

Increasing Irradiation Time (350 nm)

Hω

7.7

7.6

7.5 7.4 δ/ppm

7.3

7.2

Figure S51. 1 H NMR spectra (CD3 CN, 500 MHz) of E,E -oAzoBox4+ ⊂4DPDO upon increasingly longer exposure to UV light (350 nm, Zoom in of Figure S50). Blue dotted lines track the shifting proton resonances of 4DPDO and the red lines indicate the non-shifted 4DPDO proton resonances.

References [1] Stappert, K., Muthmann, J., Spielberg, E. T. & Mudring, A.-V. Azobenzene-based organic salts with ionic liquid and liquid crystalline properties. Crystal Growth & Design 15, 4701–4712 (2015). [2] Gong, H.-Y., Rambo, B. M., Lynch, V. M., Keller, K. M. & Sessler, J. L. “Texas-sized” molecular boxes: Building blocks for the construction of anion-induced supramolecular species via self-assembly. J. Am. Chem. Soc. 135, 6330–6337 (2013). [3] Grimme, S., Ehrlich, S. & Goerigk, L. Effect of the damping function in dispersion corrected density functional theory. J. Comp. Chem. 32, 1456–1465 (2011).

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[4] Sure, R. & Grimme, S. Comprehensive benchmark of association (free) energies of realistic host-guest complexes. J. Chem. Theory Comput. 11, 3785–3801 (2015). [5] Bruker APEX2 and SADABS, Bruker AXS, Madison, Wisconsin, USA. (2014).

S45