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Supporting Information

Living/Controlled Ring-Opening (Co)Polymerization of Lactones by Al-

based Catalysts with Different Sidearms

Wuchao Zhao, Qianyi Wang, Yunpeng Cui, Jianghua He, and Yuetao Zhang*

State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry,

Jilin University, Changchun, Jilin 130012, China

* Corresponding author email: ytzhang2009@jlu.edu.cn

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2018

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Table of contents

1. Synthesis of ligands L1-L5 and Al1-Al5 complexes .......................................................... 3

2. The overlay of 1H NMR spectra for complex Al1-Al5.................................................... 11

3. GPC traces of PCL samples produced by Al3/BnOH with different amounts of BnOH

initiator ................................................................................................................................... 12

4. Plots of Mn and Ð for PCL vs [M]0/[BnOH]0 ratio .......................................................... 13

5. 13C NMR spectra of random copolymer .......................................................................... 13

6. 13C NMR spectra of copolymers obtained with prolonged reaction time or raised

reaction temperature ............................................................................................................. 14

7. Selected polymerization results ........................................................................................ 15

8. Mark-Houwink plots of PCL ............................................................................................ 16

9. Plots of Mn and PDI of PCL vs ε-CL conversion ............................................................ 17

10. Stoichiometric reaction of Al3 and BnOH in 1:1 ratio ................................................. 17

11. GPC traces ....................................................................................................................... 18

12. References: ....................................................................................................................... 19

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1. Synthesis of ligands L1-L5 and Al1-Al5 complexes

Ligands L1-L5 were prepared according to modified literature procedures through

Mannich condensation reaction1,2 or imine condensation reaction3.

Synthesis of 2,4-di-tert-butyl-6-((butyl(methyl)amino)methyl)phenol

(L2). L2 was prepared according to a modified literature procedure.1 N-

methylbutan-1-amine (1.85 g, 21.2 mmol), paraformaldehyde (1.50 g,

50.0 mmol), and 2,4-di-tert-butylphenol (10.3 g, 50 mmol) were dissolved in ethanol

(20 mL). After refluxed for 24 h, the reaction mixture was cooled to room temperature

(RT) and then concentrated under vacuum to afford a yellow oil. After dissolved in

CH2Cl2 (100 mL), dried over MgSO4 and collected the filtrate and removed the volatiles

in vacuo, the purified yellow oil was obtained in the end. 1H NMR (500 MHz,

Chloroform-d): δ 7.24 (d, J = 2.5 Hz, 1H, Ph-H), 6.84 (d, J = 2 Hz, 1H, Ph-H), 3.68 (s, 2H,

Ar-CH2), 2.47-2.43 (m, 2H, NCH2), 2.30 (s, 3H, NCH3), 1.61-1.53 (m, 2H, CH2CH2CH2),

1.47 (s, 9H, C(CH3)3), 1.38-1.34 (m, 2H, CH2CH2CH3), 1.31 (s, 9H, C(CH3)3), 1.00-0.88 (t,

3H, J = 2 Hz, CH2 CH3).

Typical synthetic procedure for the synthesis of Al1-Al5 complexes

To a stirred solution of L (0.10 mmol) in 10 mL of dry hexane (except L5 was

dissolved in dry toluene) was added AlMe3 (0.11 mmol) dropwise in 1:1.1 ratio at RT

in an argon filled glove box. The immediate elimination of methane gas is a

noteworthy observation. The solution was allowed to warm up to room temperature.

After stirred for another 12 h and then removed the most of the solvent under

reduced pressure, the reaction mixture was put in a fridge at -35°C for 24h. Complexes

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Al1-Al3 can be collected by filtration and washed with cold pentane. Complex Al4 was

directly collected by filtered and washed with hexane, as for Al5, concentrated the

resulting reaction mixture under reduced pressure, the solids were washed by hexane

and dried in vacuo to afford Al5 as a dark red solid.

Complex Al1: 1H NMR (500 MHz, Benzene-d6, ppm): δ 7.56 (d, J = 5 Hz,

1H, Ph-H), 6.74 (d, J = 5 Hz, 1H, Ph-H), 3.17 (s, 2H, Ar-CH2), 2.35-2.28 (m,

2H, -C(H)HCH3), 2.15-2.08 (m, 2H, -C(H)HCH3), 1.70 (s, 9H, C(CH3)3), 1.40

(s, 9H, C(CH3)3), 0.46 (t, J = 7.0 Hz, 6H, CH2CH3), -0.41 (s, 6H, Al-CH3). 13C NMR (126

MHz, Benzene-d6, ppm): δ 156.9, 138.3, 137.5, 124.2, 124.1, 119.9, 57.1, 43.1, 35.0,

33.9, 31.8, 29.7, 6.8, -10.1.

Complex Al2: 1H NMR (500 MHz, Benzene-d6): δ 7.57 (d, J = 2.5 Hz, 1H,

Ph-H), 6.78 (d, J = 2.5 Hz, 1H, Ph-H), 3.63 (d, J = 13.0 Hz, 1H, Ar-CH2),

2.75 (d, J = 13.1 Hz, 1H, Ar-CH2), 2.42-2.36 (m, 1H, NCH2), 1.80-1.74 (m,

1H, NCH2), 1.70 (s, 9H, C(CH3)3), 1.67 (s, 3H, NCH3), 1.42 (s, 9H, C(CH3)3), 1.34- 0.76 (m,

4H, CH2CH2CH3), 0.66 (d, J = 14.6 Hz, 3H, CH2CH3), -0.43 (d, J = 30.8 Hz, 6H, Al-CH3). 13C

NMR (126 MHz, Benzene-d6, ppm): δ 156.5, 138.3, 137.7, 124.3, 124.1, 120.3, 61.8,

57.8, 39.5, 35.1, 33.9, 31.8, 29.7, 25.7, 20.2, 13.4, -10.0, -10.7.

Complex Al3: 1H NMR (500 MHz, Benzene-d6): δ 7.57 (d, J = 2.5 Hz, 1H,

Ph-H), 6.77 (d, J = 2.5 Hz, 1H, Ph-H), 3.70 (d, J = 13.1 Hz, 1H, Ph-CH2), 2.84

(d, J = 13.1 Hz, 1H, NCH2), 2.57 (m, 1H, NCH2), 2.19-2.12 (m, 2H, NCH2),

2.05 (m, 1H, NCH2), 1.85 (s, 6H, NCH3), 1.84 (s, 6H, NCH3), 1.70 (s, 9H, C(CH3)3), 1.41 (s,

9H, C(CH3)3), -0.40 (d, J = 30 Hz, 6H, Al-CH3). 13C NMR (126 MHz, Benzene-d6, ppm): δ

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156.6, 138.3, 137.9, 128.0, 124.4, 124.2, 120.1, 62.2, 55.3, 54.1, 45.2, 40.1, 35.1, 31.8,

29.6, -10.1, -10.3.

Complex Al4: 1H NMR (500 MHz, Benzene-d6): δ 8.31 (dt, J = 5.3, 1.3

Hz, 1H, Ar-H), 7.72 (d, J = 2.6 Hz, 1H, NCH), 7.41 (t, J = 1.5 Hz, 1H, Ar-H),

6.87-6.79 (m, 2H, Ar-H), 6.50-6.43 (m, 1H, Ar-H), 6.22 (d, 1H, J = 8 Hz,

1H, Ar-H) 3.85 (s, 2H, CH2), 1.76 (s, 9H, C(CH3)3), 1.38 (s, 9H, C(CH3)3), -0.16 (s, 6H, Al-

CH3). 13C NMR (126 MHz, Benzene-d6, ppm): δ 172.2, 165.8, 153.4, 146.2, 140.8, 137.3,

136.2, 131.2, 127.7, 122.7, 120.2, 117.8, 58.9, 35.3, 33.8, 31.3, 29.5, -5.3.

Complex Al5: 1H NMR (500 MHz, Benzene-d6): δ 8.48 (dd, J = 4.6, 1.6

Hz, 1H, Ar-H), 8.12 (s, 1H, CHN), 7.77 (d, J = 2.7 Hz, 1H, Ar-H), 7.30 (dd,

J = 8.2, 1.6 Hz, 1H, Ar-H), 7.07-6.92 (m, 3H, Ar-H), 6.68-6.58 (m, 2H,

Ar-H), 1.79 (s, 9H, C(CH3)3), 1.39 (s, 9H, C(CH3)3), -0.05 (s, 6H, Al-CH3). 13C NMR (126

MHz, Benzene-d6, ppm): δ 168.6, 165.5, 146.1, 141.8, 141.5, 139.3, 136.9, 136.5, 132.9,

128.4, 128.0, 127.6, 124.0, 122.3, 118.4, 114.6, 35.4, 33.9, 31.2, 29.5, -4.2.

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Figure S1. 1H NMR spectrum of Al1 (benzene-d6, 500 MHz).

Figure S2. 13C NMR spectrum of Al1 (benzene-d6, 126 MHz).

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Figure S3. 1H NMR spectrum of Al2 (benzene-d6, 500 MHz).

Figure S4. 13C NMR spectrum of Al2 (benzene-d6, 126 MHz).

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Figure S5.1H NMR spectrum of Al3 (benzene-d6, 500 MHz).

Figure S6. 13C NMR spectrum of Al3 (benzene-d6, 126 MHz).

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Figure S7.1H NMR spectrum of Al4 (benzene-d6, 500 MHz).

Figure S8.13C NMR spectrum of Al4 (benzene-d6, 126 MHz).

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Figure S9.1H NMR spectrum of Al5 (benzene-d6, 500 MHz).

Figure S10.13C NMR spectrum of Al5 (benzene-d6, 126 MHz).

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2. The overlay of 1H NMR spectra for complex Al1-Al5

Figure S11. The overlay of 1H NMR spectra for complex Al1-Al5 (benzene-d6, 500

MHz).

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3. GPC traces of PCL samples produced by Al3/BnOH with different amounts of BnOH

initiator

Figure S12. GPC traces for PCL samples produced by polymerizations with a fixed [ε-

CL]0/[Al3]0 = 800:1 ratio and different amounts of BnOH at RT.

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4. Plots of Mn and Ð for PCL vs [M]0/[BnOH]0 ratio

Figure S13. Plots of Mn and Ð for PCL vs [M]0/[BnOH]0 ratio produced by a) Al2/BnOH

and b) Al1/BnOH (blue), Al3/BnOH (red) and Al4/BnOH (black) .

5. 13C NMR spectra of random copolymer

Figure S14. 13C NMR spectra of linear random PCL-co-PVL produced by Al4/BnOH.

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6. 13C NMR spectra of copolymers obtained with prolonged reaction time or raised

reaction temperature

Figure S15. 13C NMR spectra of copolymers produced after 10 h of full monomer

consumption by (a) Al1/BnOH; (b) Al2/BnOH; (c) Al3/BnOH and (d) 13C NMR

spectra of copolymers produced after 24h of full monomer consumption by

Al4/BnOH in toluene at RT.

Figure S16 13C NMR spectra of copolymers produced by Al1/BnOH and (b) Al2/BnOH

system heated at 50 °C for 10 h after reach monomer completion.

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7. Selected polymerization results

Table S1. Selected polymerization results for ROP of ε-CL and δ-VL by Al1-Al5a

Run Al M/Al

Time

(h)

Conv.b

(%)

Mn c

(kg/mol)

Mw c

(kg/mol) Đ

I* d

(%)

1 Al1 100CL 24.0 5.0 71.8 137 1.94 <1

2 Al1 100VL 24.0 3.7 50.7 91.2 1.80 <1

3 Al2 100CL 24.0 44.8 101 153 1.51 5

4 Al2 100VL 24.0 57.7 94.8 139 1.47 6

5 Al3 100CL 24.0 15.7 91.3 129 1.41 2

6 Al3 100VL 24.0 26.2 335 614 1.83 <1

7 Al4 100CL 24.0 58.2 64.1 91.1 1.42 10

8 Al4 100VL 24.0 83.3 28.8 42.5 1.48 29

9 Al5 100CL 24.0 62.1 75.3 106 1.40 9

10 Al5 100VL 24.0 87.8 38.0 51.3 1.35 23 aCondition: For polymerization with a 200 M/Al/BnOH ratio carried out at RT in toluene (Tol),

where [M]0 = [monomer]0 = 1.0 M. b Monomer conversions measured by 1H NMR. c Absolute

molecular weight (Mw) measured by GPC using a light scattering detector. Number average

molecular weight (Mn) is calculated from Mw/Đ. d Initiation efficiency (I*)% =

Mn(calcd)/Mn(exptl) × 100, where Mn(calcd) = MW(M) × ([M]/[I]) × (conversion) + MW of

chain-end groups.

Table S2. Polymerization results of kinetic studies a

Run Al M/Al/BnOH Time

(h)

Conv.b

(%)

Mnc

(kg/mol)

Mwc

(kg/mol) Đ

I*d

(%)

1 Al3 800:1:1 5.5 96.0 77.1 115 1.50 114

2 Al3 800:2:1 11.5 90.0 79.5 110 1.38 103

3 Al3 800:4:1 11.5 89.5 80.9 110 1.36 101

4 Al3 800:8:1 11.5 89.0 80.2 108 1.35 102 aCondition: For polymerization with a 200 M/Al/BnOH ratio carried out at RT in toluene (Tol),

where [M]0 = [monomer]0 = 1.0 M. b Monomer conversions measured by 1H NMR. c Absolute

molecular weight (Mw) measured by GPC using a light scattering detector. Number average

molecular weight (Mn) is calculated from Mw/Đ. dInitiation efficiency (I*)% =

Mn(calcd)/Mn(exptl) × 100, where Mn(calcd) = MW(M) × ([M]/[I]) × (conversion) + MW of

chain-end groups.

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Table S3. ROP of ε-CL initiated with different amounts of BnOH a

Run Al M/Al/BnOH Time

(h)

Conv.b

(%)

Mnc

(kg/mol)

Mwc

(kg/mol) Đ

I*d

(%)

1 Al3 800:1:1 5.5 96.0 77.1 116 1.50 114

2 Al3 800:1:2 2.0 95.8 32.4 49.7 1.53 267

3 Al3 800:1:3 2.0 98.4 25.3 36.6 1.44 355

4 Al3 800:1:5 1.5 97.7 15.0 18.1 1.20 595

5 Al3 800:1:10 1.5 95.1 7.6 8.5 1.12 1142 aCondition: For polymerization with a 200 M/Al/BnOH ratio carried out at RT in toluene (Tol),

where [M]0 = [monomer]0 = 1.0 M. b Monomer conversions measured by 1H NMR. c Absolute

molecular weight (Mw) measured by GPC using a light scattering detector. Number average

molecular weight (Mn) is calculated from Mw/Đ. d Initiation efficiency (I*)% =

Mn(calcd)/Mn(exptl) × 100, where Mn(calcd) = MW(M) × ([M]/[I]) × (conversion) + MW of

chain-end groups.

8. Mark-Houwink plots of PCL

Figure S17. Mark-Houwink plots of PCL1 (prepared after reaching monomer

completion) and PCL2 (kept at RT for 24 h after reaching monomer completion)

produced by Al3/BnOH under different conditions.

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9. Plots of Mn and PDI of PCL vs ε-CL conversion

Figure S18. Plots of Mn and PDI of PCL vs ε-CL conversion catalyzed by Al/BnOH at rt.

Conditions: (a) [ε-CL0]/[Al3]0/[BnOH]0 = 800:1:1; (b) [ε-CL]0/[Al4]0/[BnOH]0 = 200:1:1

10. Stoichiometric reaction of Al3 and BnOH in 1:1 ratio

Figure S19. 1H NMR spectrum for the stoichiometric reaction of Al3 and BnOH in 1:1

ratio.

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11. GPC traces

Figure S20. GPC traces of PCL samples obtained from the ROP of ε-CL with different [ε-

CL]0//[Al]0/[BnOH]0 ratio (Al= (a) Al1; (b) Al2; (c) Al3; (d) Al4) at RT.

Figure S21. The overlay of GPC traces for homopolymer PCL (black), di-block

copolymer PCL-b-PVL (red) and tri-block copolymer PCL-b-PVL-b-PCL (blue)

produced by (a) Al1/BnOH; (b) Al2/BnOH; (c) Al3/BnOH; (d) Al4/BnOH system.

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12. References:

(1) Roymuhury, S. K.; Chakraborty, D.; Ramkumar, V. Aluminium complexes

bearing N,O-aminophenol ligands as efficient catalysts for the ring opening

polymerization of lactide. Eur. Polym. J. 2015, 70, 203-214.

(2) Williams, C. K.; Breyfogle, L. E.; Choi, S. K.; Nam, W.; G, V.; Young, J.; Hillmyer,

M. A.; Tolman, W. B. A Highly Active Zinc Catalyst for the Controlled Polymerization of

Lactide. J. Am. Chem. Soc. 2003, 125, 11350-11359.

(3) Cameron, P. A.; Gibson, V. C.; Redshaw, C.; Segal, J. A.; White, A. J. P.; Williams,

D. J. Synthesis and characterisation of neutral and cationic alkyl aluminium complexes

bearing N,O-Schiff base chelates with pendant donor arms. Dalton Trans. 2002, 415-

422.