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Insight Into the Crystallization of Amorphous Imine-Linked Polymer Networks to 2D Covalent Organic Frameworks

Brian J. Smith, Anna C. Overholts, Nicky Hwang, and William R. Dichtel*

Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, New York, 14853-1301 USA

Supporting Information

Table of Contents

I. Materials and Instrumentation S–2

II. Experimental Protocols S–3

III. Additional Characterization

A. Powder X-ray diffraction data S–5

B. N2 Isotherm and BET surface area determination S–7

C. SEM S–12

Correspondence Address

Professor William R. Dichtel Department of Chemistry and Chemical Biology

Cornell University Baker Laboratory

Ithaca, NY 14853-1301 (USA) Tel: (+1)-607-254-2356 Fax: (+1)-607-255-4137

Email: wdichtel@cornell.edu

Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2016

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I. Materials and Instrumentation Materials. Reagents were purchased from commercial sources and used without

further purification. MeOH and toluene were purchased from commercial sources

and purified using a custom-built alumina-column based solvent purification

system. Other solvents were purchased from commercial sources and dried over

activated 3Å molecular sieves.

Instrumentation. Infrared spectra of solid samples were recorded using a

ThermoNicolet iS10 FT-IR spectrometer with a diamond ATR attachment and are

uncorrected.

Surface area measurements were conducted on a Micromeritics ASAP

2020 Accelerated Surface Area and Porosimetry Analyzer using samples

degassed at 90 °C for 24 h and backfilled with N2. N2 isotherms were generated

by incremental exposure to ultra high purity nitrogen up to 1 atm in a liquid

nitrogen (77 K) bath and surface parameters were determined using BET

adsorption models included in the instrument software (Micromeritics ASAP 2020

V4.00).

Powder X-ray diffraction (PXRD) patterns were obtained on a Scintag

Theta-Theta Powder X-Ray Diffractometer in reflectance Bragg-Brentano

geometry employing Cu Kα line focused radiation at 2200 W (40 kV, 40 mA)

power and equipped with a Ge crystal detector fitted with a 0.3 mm radiation

entrance slit. Samples were mounted on zero background sample holders by

dropping powders from a spatula and then leveling the sample surface with a

glass microscope slide. No sample grinding or sieving was used prior to analysis.

Crystallite size was determined by applying the Scherrer equation to the powder

patterns using MDI JADE.

Scanning electron microscopy was performed on a LEO 1550 FESEM

(Keck SEM) operating at 2.00 kV and a working distance of 3 – 4 mm with an

aperture size of 20 µm. Samples were prepared by adsorption onto a silicon

wafer, which was then attached to a flat aluminum platform sample holder. The

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sample was then placed directly into the instrument. No metal coating was

applied.

Sonication was performed with a Branson 3510 ultrasonic cleaner with a

power output of 100W and a frequency of 42 kHz.

The Accelrys Materials Studio (version 5.5) program suite was used to

simulate the powder diffraction. The structures were optimized using the

Geometry Optimization routine including energy minimization with cell

parameters optimization, using the parameters from the Universal Force Field.

The PXRD was calculated for the optimized structures with the Reflex Plus

module.

II. Experimental Protocols General conditions for homogeneous synthesis of TAPB-PDA COF. 1,3,5-tris(4-aminophenyl)benzene (55 mg, 0.16 mmol) and terephthaldehyde (31

mg, 0.23 mmol) were combined in a scintillation vial with a dioxane / mesitylene

solution (4:1 v/v, 6.3 mL). The solution was heated to 70 ˚C for 3 minutes to

ensure dissolution and then cooled to room temperature. Distilled H2O (1.2 mL)

was added to the solution, followed by glacial CH3CO2H (1.8 mL). The resulting

suspension was sealed and heated to 70 ˚C for 72 hrs. The COF solid was

isolated by filtration, rinsed with toluene, and subsequently dried under vacuum,

yielding a yellow powder. (66 mg, 85 % yield)

Conditional survey of acetic acid and water for TAPB-PDA COF synthesis. A stock solution of the monomers in dioxane / mesitylene solution (4:1 v/v) was

prepared as described above. Various mixtures of distilled H2O, glacial

CH3CO2H, and additional dioxane / mesitylene were added to the stock solution

(1.0 mL) to obtain a final volume of 1.7 mL for each experiment (0.015 M [TAPB],

0–0.3 mL water, 0–0.4 mL glacial acetic acid). Each reaction mixture was heated

to 70 ˚C for 3 days, after which the COF or amorphous polymer precipitates were

isolated as described above and subsequently characterized by PXRD.

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Homogeneous synthesis of TAPB-PDA amorphous network. 1,3,5-tris(4-aminophenyl)benzene (100 mg, 0.28 mmol) and terephthaldehyde

(57 mg, 0.43 mmol) were combined in a scintillation vial with dioxane /

mesitylene solution (4:1 v/v, 11.4 mL), and heated to 70 ˚C for 3 min to ensure

dissolution and then cooled to room temperature. Distilled H2O (2.3 mL) was

added to the solution, followed by glacial CH3CO2H (3.4 mL). The resulting solid

was isolated by filtration after 15 min, rinsed with toluene, and subsequently dried

under vacuum, yielding a yellow powder. (0.41 mg, 95 % yield)

Conversion of amorphous network to TAPB-PDA COF. The TAPB-PDA

amorphous network (80 mg) was added to a scintillation vial with dioxane /

mesitylene solution (4:1 v/v, 6.4 mL). Distilled H2O (1.3 mL) was added to the

solution, followed by glacial CH3CO2H (1.9 mL). The resulting suspension was

heated to 70 ˚C for 48 hours, under atmospheric pressure. The COF solid was

isolated by filtration, rinsed with toluene, and subsequently dried under vacuum,

yielding a yellow powder. (60 mg, 75% yield)

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III. Additional Characterization A. Powder X-ray diffraction

Figure S1. Partial powder X-ray diffraction (2θ 2–4˚) of TAPB-PDA COF synthesized in the presence of water and/or glacial acetic acid, added to 1 mL of stock (final concentration normalized to 0.015 M [TAPB]). Reaction conditions: 70 ˚C, 72 h. Conditions in gray yielded no solid.

!

Water

(uL/mL)

300

200

100

50

10

0

0 25 100 200 300 400

Acid (uL/mL)

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Figure S2. Powder X-ray diffraction of initial amorphous imine network and TAPB-PDA COF after resubjection to the reaction conditions (70 ˚C, 48 h).

Figure S3. Powder X-ray diffraction of initial amorphous imine network after resubjection to the reaction conditions (room temperature, 6 days).

Inte

nsity

121086422-Theta (º)

Amorphous

TAPB-PDA COF

Inte

nsity

121086422-Theta (º)

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B. N2 Isotherm and BET surface area determination

Figure S4. N2 adsorption isotherm (77 K) and surface area data analysis of TAPB-PDA COF synthesized from homogeneous conditions.

0

50

100

150

200

250

300

350

0 0.2 0.4 0.6 0.8 1

cm³/g

STP

P/P0

Adsorption

Desorption

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00

Incr

emen

tal P

ore

Volu

me

50454035302520Pore Width (A)

0.E+00

2.E+04

4.E+04

6.E+04

8.E+04

1.E+05

1.E+05

1.E+05

2.E+05

0 0.2 0.4 0.6 0.8 1

Q(P

0-P)

P/P0

0.E+00

2.E-04

4.E-04

6.E-04

8.E-04

1.E-03

1.E-03

1.E-03

2.E-03

2.E-03

0 0.1 0.2 0.3

(P/P

o)/(Q

*(1-

P/P

o)

P/P0

BET Surface Area P/P0 (m2 g-1) R2

0.05 – 0.20 610 0.999 0.05 – 0.22 625 0.997 0.05 – 0.24 657 0.990 0.05 – 0.27 750 0.931

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Figure S5. N2 adsorption isotherm (77 K) and surface area data analysis of amorphous TAPB-PDA synthesized at room temperature from homogeneous conditions.

0

2

4

6

8

10

12

14

16

18

20

0 0.2 0.4 0.6 0.8 1

cm³/g

STP

P/P0

Adsorption

Desorption

1.2x10-3

1.0

0.8

0.6

0.4

0.2

0.0

Incr

emen

tal P

ore

Volu

me

50454035302520Pore Width (A)

0.E+00

5.E+02

1.E+03

2.E+03

2.E+03

3.E+03

3.E+03

4.E+03

0 0.2 0.4 0.6 0.8 1

Q(P

0-P)

P/P0

0.E+00

1.E-02

2.E-02

3.E-02

4.E-02

5.E-02

6.E-02

0 0.1 0.2 0.3

(P/P

o)/(Q

*(1-

P/P

o)

P/P0

BET Surface Area P/P0 (m2 g-1) R2

0.05 – 0.20 18 0.999

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Figure S6. N2 adsorption isotherm (77 K) and surface area data analysis of amorphous TAPB-PDA resubjection to the reaction conditions (70 ˚C, 24 h).

0

10

20

30

40

50

60

70

80

90

0 0.2 0.4 0.6 0.8 1

cm³/g

STP

P/P0

Adsorption

Desorption

14x10-3

12

10

8

6

4

2

0

Incr

emen

tal P

ore

Volu

me

50454035302520Pore Width (A)

0.E+00

5.E+03

1.E+04

2.E+04

2.E+04

3.E+04

0 0.2 0.4 0.6 0.8 1

Q(P

0-P)

P/P0

0.E+00

5.E-04

1.E-03

2.E-03

2.E-03

3.E-03

3.E-03

4.E-03

4.E-03

5.E-03

0 0.1 0.2 0.3 0.4

(P/P

o)/(Q

*(1-

P/P

o)

P/P0

BET Surface Area P/P0 (m2 g-1) R2

0.05 – 0.22 126 0.999 0.05 – 0.24 132 0.991 0.05 – 0.29 136 0.992

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Figure S7. N2 adsorption isotherm (77 K) and surface area data analysis of amorphous TAPB-PDA resubjection to the reaction conditions (70 ˚C, 48 h).

0

20

40

60

80

100

120

140

160

180

0 0.2 0.4 0.6 0.8 1

cm³/g

STP

P/P0

Adsorption

Desorption

50x10-3

40

30

20

10

0

Incr

emen

tal P

ore

Volu

me

50454035302520Pore Width (A)

0.E+00

1.E+04

2.E+04

3.E+04

4.E+04

5.E+04

6.E+04

0 0.2 0.4 0.6 0.8 1

Q(P

0-P)

P/P0

0.E+00

2.E-03

4.E-03

6.E-03

8.E-03

1.E-02

1.E-02

0 0.1 0.2 0.3 0.4

(P/P

o)/(Q

*(1-

P/P

o)

P/P0

BET Surface Area P/P0 (m2 g-1) R2

0.05 – 0.20 283 0.999 0.05 – 0.22 291 0.997 0.05 – 0.24 311 0.983 0.05 – 0.29 330 0.977

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Figure S8. N2 adsorption isotherm (77 K) and surface area data analysis of amorphous TAPB-PDA resubjection to the reaction conditions (room temperature, 6 days).

0

20

40

60

80

100

120

140

160

180

0 0.2 0.4 0.6 0.8 1

cm³/g

STP

P/P0

Adsorption

Desorption

40x10-3

30

20

10

0

Incr

emen

tal P

ore

Volu

me

50454035302520Pore Width (A)

0.E+00

1.E+04

2.E+04

3.E+04

4.E+04

5.E+04

6.E+04

0 0.2 0.4 0.6 0.8 1

Q(P

0-P)

P/P0

0.E+00

1.E-03

2.E-03

3.E-03

4.E-03

5.E-03

0 0.1 0.2 0.3 0.4

(P/P

o)/(Q

*(1-

P/P

o)

P/P0

BET Surface Area P/P0 (m2 g-1) R2

0.05 – 0.20 284 0.999 0.05 – 0.22 291 0.998 0.05 – 0.24 310 0.986 0.05 – 0.29 330 0.981

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C. SEM characterization

Figure S9. SEM of amorphous TAPB-PDA. Scale bar is 2 µm.

Figure S10. SEM of TAPB-PDA COF. Scale bar is 2 µm.

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Figure S11. SEM of TAPB-PDA COF. Scale bar is 200 nm.