Synthesis of hexacarboxylic acid linker based metal organic frameworks for applications in selective co2 capture and chemical fixation of co2

Atom colors: Zn for MOF-5 and Cu for HKUST-1, blue polyhedra; C, black; O, red; all H atoms are omitted for clarity.. Atom colors: Cu, blue polyhedra; C, black; O, red; N, light blue; a

VIETNAM NATIONAL UNIVERSITY HCMC

UNIVERSITY OF SCIENCE

NGUYEN THI KIEU PHUONG

SYNTHESIS OF HEXACARBOXYLIC ACID BASED METAL-ORGANIC FRAMEWORKS FOR

PhD THESIS in CHEMISTRY

HOCHIMINH CITY – 2018

VIETNAM NATIONAL UNIVERSITY HCMC

UNIVERSITY OF SCIENCE

NGUYEN THI KIEU PHUONG

SYNTHESIS OF HEXACARBOXYLIC ACID BASED METAL-ORGANIC FRAMEWORKS FOR

Major: Theoretical and Physical Chemistry

Major Code: 62440119

Reviewer 1: Prof Dr Sc Luu Cam Loc

Reviewer 2: Assoc Prof Dr Tran Ngoc Quyen

Reviewer 3: Dr Pham Cao Thanh Tung

Independent reviewer 1: Prof Dr Sc Luu Cam Loc

Independent reviewer 2: Assoc Prof Dr Pham Thanh Huyen

SUPERVISOR

1 Assoc Prof Dr Ton That Quang

2 Assoc Prof Dr Nguyen Thai Hoang

HOCHIMINH CITY – 2018

TABLE OF CONTENTS

LIST OF FIGURES 5

LIST OF SCHEMES AND TABLES 13

LIST OF ABBREVIATIONS 15

ASSURANCE 16

ACKNOWLEDGMENTS 17

Abstract of the Dissertation 19

Chapter One 21

Introduction of Metal-Organic Frameworks for Applications in Selective CO2 Capture and Chemical Fixation of CO2 21

1.1 Introduction of Metal-Organic Framework (MOF) 21

1.1.1 Metal-Organic Framework (MOF) and Reticular Chemistry 21

1.1.2 Introduction of Hexacarboxylic-Acid-based Organic Building and Inorganic Building Units 26

1.2 Carbon Dioxide Capture and Separation 32

1.3 MOFs for Selective CO2 Capture 36

1.3.1 MOFs with Open Metal Sites 37

1.3.2 MOFs Functionalized by Nitrogen Bases 38

1.3.3 MOFs Controlled Pore Size 40

1.4 Introduction of CO2 Conversion for Fine Chemicals 41

1.4.1 Introduction of Cycloaddition of CO2 to Epoxides for Synthesis of Cyclic Carbonate 43

1.4.2 Mechanism of Cycloaddition of CO2 to Epoxides 45

1.4.3 One-pot Oxidative Carboxylation of Styrene and CO2 Forming Styrene

Carbonate 49

1.5 MOF Materials as Heterogeneous Catalysts for the Cycloaddition of CO2 to Epoxides 51

1.5.1 MOFs with active Lewis acid metal sites 53

1.5.2 MOFs with Dual Catalytic Metal Centers 54

1.5.3 MOFs with Both Acid and Base Active Sites 56

1.6 Scope of the Dissertation 57

Chapter Two 59

Experimental 59

2.1 Materials and Analytical Techniques 59

2.1.1 Materials 59

2.1.2 Analytical Techniques 61

2.2 Synthesis of 1′,2′,3′,4′,5′,6′-hexakis(4-carboxyphenyl)-benzene (H6CPB) 63

2.3 Synthesis of MOF-888, MOF-889, MOF-890, MOF-892, and MOF-893 65

2.3.1 Synthesis of MOF-888 65

2.3.2 Synthesis of MOF-889 65

2.3.3 Synthesis of MOF-890 66

2.3.4 Synthesis of MOF-892 67

2.3.5 Synthesis of MOF-893 67

2.4 Gas Adsorption Properties 68

2.4.1 Determination of Surface Area 68

2.4.2 Determine Pore Size Distribution 69

2.4.3 Calculation of Gas Selectivity by Henry’s Law 70

2.4.4 Breakthrough Measurements 71

2.5 Catalysis Study on Chemical Fixation of CO2 to Cyclic Carbonate Synthesis 72

2.5.1 General Procedures 72

2.5.2 Catalytic Cycloaddition of CO2 to Epoxides 77

2.5.3 Methyl Esterification of MOF-892 78

2.5.4 Oxidative Carboxylation of CO2 and Styrene 79

2.5.5 Purification of Cyclic Carbonates 80

Chapter Three 81

Result and Discussion 81

3.1 Synthesis of a Series of Hexacarboxylic Acid Linker-Based Metal−Organic Frameworks and their Selective CO2 Capture 81

3.1.1 Overview 81

3.1.2 Synthesis of 1′,2′,3′,4′,5′,6′-hexakis(4-carboxyphenyl)-benzene (H6CPB) 83

3.1.3 Crystal Structures of MOF-888, -889, and -890 85

3.1.4 Characterization of MOF-888, -889, and -890 93

3.1.5 Gas Adsorption Properties 100

3.2 Synthesis of Zirconium-Based Metal−Organic Frameworks as Reusable Catalysts for Chemical Fixation of CO2 108

3.2.1 Overview 108

3.2.2 Crystal Structures of MOF-892 and MOF-893 110

3.2.3 Characterization of MOF-892 and MOF-893 115

3.2.4 Catalytic Cycloaddition of CO2 to Epoxides and Olefins 123

Conclusion and Outlook 147

Conclusion 147

Outlook 148

New MOFs for Gas Separation 148

New MOF-based Catalysts for Chemical Fixation of CO2 149

PUBLICATIONS 150

REFERENCES 151

APPENDIX 169

Appendix A: Synthesis of a Series of Hexacarboxylic Acid Linker-Based Metal−Organic Frameworks and their Selective CO2 Capture 170

Appendix B: Synthesis of Zirconium-Based Metal−Organic Frameworks as Reusable Catalysts for Chemical Fixation of CO2 183

LIST OF FIGURES

Figure 1.1 Metal-containing clusters and their corresponding SBUs Atom colors: metal,

blue polyhedra; C, black; O, red 22

Figure 1.2 Rods with points of extension forming (A) zigzag ladder,5 (B) infinite,6 (C) twisted ladder.5 Atom colors: metal, blue polyhedra; C, black; O, red 22

Figure 1.3 Organic linkers (top) and their corresponding SBUs (bottom) Atom colors: C,

black; O, red 23

Figure 1.4 (A) MOF-5 showing the abstraction of the Zn4O(−CO2)6 SBU as an octahedron,

the ditopic terephthalate linker as a linear rod, and their assembly into the pcu net shown in

augmented form (B) HKUST-1 showing the Cu2(−CO2)4 paddle wheel abstracted as a

square, the tritopic linker as a triangle, and their combination to form the tbo net shown in augmented form tbo-a Atom colors: Zn (for MOF-5) and Cu (for HKUST-1), blue

polyhedra; C, black; O, red; all H atoms are omitted for clarity The large yellow, orange and pink spheres represent the largest sphere that would occupy the cavity All hydrogen atoms are omitted for clarity 24

Figure 1.5 Representative binodal nets in reticular chemistry.9 25

Figure 1.6 The isoreticular (maintaining same topology) expansion of archetypical MOFs

resulting from discrete inorganic SBUs combined with ditopic organic linkers to obtain

MOFs in a pcu net Atom colors: Zn, blue polyhedra; C, black; O, red The yellow spheres

are placed in the structure to indicate space in the cage 26

Figure 1.7 Topologies and shapes for hexatopic linkers: (a−c) trigonal prisms, (d, e)

octahedra, and (f-g) hexagon 27

Figure 1.8 Schematic of the crystal structure of a NU-111, -100, and -110 from left to right,

respectively Color code: Cu, blue; C, black; O, red All H atoms are omitted for clarity The yellow and orange spheres are placed in the structure to indicate space in the cage 28

Figure 1.9 Crystal structure of NU-110E Hexacarboxylic linker (H6L) connects to a Zr6

SBU forming the three-dimensional structure adopting she topology Color code: Cu, blue;

C, black; O, red All H atoms are omitted for clarity The yellow and orange spheres are placed in the structure to indicate space in the cage 28

Figure 1.10 Hexaarylbenzene based-covalent organic framework 30 Figure 1.11 Inorganic SBUs of various coordination numbers are known in the family of

the zirconium-based MOFs Atom colors: Zr, blue polyhedra; C, black; O, red All H atoms are omitted for clarity 31

Figure 1.12 Representative binodal nets in reticular chemistry adopted in zirconium MOFs.

32

Figure 1.13 (A) Atmospheric CO2 concentration (at Mauna Loa Observatory), showing the continuing and increase of CO2 in atmosphere during 1958–2017 (B) Atmospheric concentrations of the greenhouse gases carbon dioxide (CO2, green), methane (CH4, orange) and nitrous oxide (N2O, red) determined from ice core data (dots) and from direct atmospheric measurements (lines) 33

Figure 1.14 Three main types of CO2 capture in the current technology 34

Figure 1.15 Crystal structure of M-MOF-74 DOT link is joined by an infinite metal oxide

SBU to make the three-dimensional structure with one-dimensional hexagonal channels and

adopting the etb topology Atom colors: metal, blue polyhedra; C, black; O, red All H atoms

are omitted for clarity 38

Figure 1.16 Crystal structure of bio-MOF-11 Co2+-adeninate-acetate clusters (A) are bridged by adeninate to generate an extended 3D porous structure (B) The framework

adopts the augmented lvt topology (C) (D) CO2 (circles) and N2 (triangles) isotherms at 273

(black) and 298 K (red) (C) Isosteric heat of adsorption of CO2 Atom colors: Co, blue polyhedra; C, black; O, red All H atoms are omitted for clarity 39

Figure 1.17 Crystal structure of Mg(dobpdc)2-dmpn and structure of Mg2(dobpdc)− (dmpn−CO2) after activation of Mg(dobpdc)2-dmpn and dosing with 1 bar of CO2, forms bridging carbamic acid pairs Atom colors: Mg, blue polyhedra; C, black; O, red All H atoms are omitted for clarity 40

Figure 1.18 Crystal structure of PCN-200 and gas adsorption isotherms for CO2 and N2 of PCN-200 Atom colors: Cu, blue polyhedra; C, black; O, red All H atoms are omitted for clarity 41

Figure 1.19 The possible applications of CO2 in chemical syntheses 42

Figure 1.20 Common co-catalysts used in the reaction of CO2 and epoxides 48

Figure 1.21 Most probable sites of nucleophilic attack for different epoxides 49 Figure 1.22 Hf-NU-1000 shows high catalytic activity for the activation of epoxides leading

to the regioselective and enantio-retentive formation of 1,2-bifuctionalized systems Atom colors: Hf, blue; C, black; O, red, all H atoms are omitted for clarity 53

Figure 1.23 Crystal structure of MMCF-2 Tetracarboxylic linker, H4LCu2, connects to a

paddle-wheel copper cluster forming the three-dimensional structure adopting nbo topology

Atom colors: Cu, blue polyhedra; C, black; O, red; N, light blue; all H atoms are omitted for clarity 54

Figure 1.24 Crystal structure of PCN-224(Co) Tetracarboxylic linker (H4L) connects to a Zr6 SBU forming the three-dimensional structure adopting she topology Atom colors: Zr, blue polyhedra; C, black; O, red; N, light blue; Co, pink; all H atoms are omitted for clarity 55

Figure 1.25 Synthesis of Im-UiO-66 and (I-)Meim-UiO-66 via solvothermal reaction and

by post-synthetic modification method, respectively Atom colors: Zr, green polyhedra; C, black; O, red; N, blue All H atoms are omitted for clarity 56

Figure 1.26 The route to synthetic route in the preparation of catalyst MIL-101-N(n-Bu)3Br

and MIL-101-P(n-Bu)3Br (R = N or P) 57

Figure 2.1 Apparatus used for collection of breakthrough curves 71 Figure 2.2 Calibration curve of styrene oxide (SO, top) and styrene carbonate (SC, bottom)

to determine the conversion, selectivity and GC yield of the cycloaddition reaction 74

Figure 2.3 Calibration curve of propylene oxide (PO, top) and propylene carbonate (PC,

bottom) to determine the conversion, selectivity and GC yield of the cycloaddition reaction 75

Figure 2.4 Calibration curve of cyclohexene oxide (CO, top) and cyclohexene carbonate

(CC, bottom) to determine the conversion, selectivity and GC yield of the cycloaddition reaction 76

Figure 2.5 Calibration curve of styrene to determine the conversion, selectivity and GC

yield of the one-pot reaction 77

Figure 3.1 ORTEP representation of the asymmetric unit of MOF-888 displayed with 50%

probability The site occupancy factors of Ni atoms are 0.5 Atom colors: Ni, violet; O, red;

H, white; and C, grey 87

Figure 3.2 Crystal structure of MOF-888 (A) Linking of hexagonal CPB and triangular

Ni(CO2)3 SBUs result in (B) MOF-888 (C) The structure of MOF-888 adopts the kgd topology Atom colors: Ni, blue polyhedra; C, black, O, red, all H atoms are omitted for clarity 88

Figure 3.3 ORTEP representation of the asymmetric unit of MOF-889 displayed with 50%

probability The site occupancy factors of the disordered fragments for DEF and EtOH are 0.5 each Except for the C atoms in one EtOH (O16-C58-C59), the other EtOH C atoms were refined isotropically The N and C atoms in the disordered DEF were also treated isotropically due to their abnormal anisotropic thermal parameters Atom colors: Mg, turquoise; O, red; H, white; N, blue; and C, grey 89

Figure 3.4 Crystal structure of MOF-889 (A) Linking of hexagonal CPB and infinite

[Mg2(CO2)4(CO2H)2(EtOH)2]∞ (red and blue binodal rod) SBUs result in (B) MOF-889 (C)

The structure of MOF-889 adopts the yav topology Atom colors: Mg, blue polyhedra; C,

black, O, red, all H atoms, except for those participating in hydrogen bonding, are omitted for clarity 90

Figure 3.5 ORTEP representation of the asymmetric unit of MOF-890 displayed with 50%

probability Besides Cu and O1w atoms, all non-H atoms were treated isotropically due to their abnormal anisotropic thermal parameters Atom colors: Cu, violet; O, red; C, grey; H, white; and N, blue 91

Figure 3.6 Crystal structure of MOF-890 (A) Linking of hexagonal CPB and trigonal

prismatic Cu3(CO2)6 SBUs result in (B) MOF-890 (C) The structure of MOF-890 adopts

the novel htp topology Atom colors: Cu, blue polyhedra; C, black, O, red, all H atoms are

omitted for clarity 92

Figure 3.7 Comparison of simulated (black) PXRD pattern from the crystal data with those

of the experimental as-synthesized (red) and activated (blue) of MOF-888 93

Figure 3.8 Comparison of simulated (black) PXRD pattern from the crystal data with those

of the experimental as-synthesized (red) and activated (blue) of MOF-889 94

Figure 3.9 Comparison of simulated (black) PXRD pattern from the crystal data with those

of the experimental as-synthesized (red) and activated (blue) MOF-890 94

Figure 3.10 TGA traces of activated MOF-888 at a heating rate of 5 °C min-1 under air flow 95

Figure 3.11 TGA traces of activated MOF-889 at a heating rate of 5 °C min-1 under air flow 96

Figure 3.12 TGA traces of activated MOF-890 at a heating rate of 5 °C min-1 under air flow 96

Figure 3.13 N2 isotherms of MOF-888 (red), MOF-889 (green), and MOF-890 (blue) at 77

K Filled and open symbols represent adsorption and desorption branches, respectively The connecting curves are guides for the eye 97

Figure 3.14 The pore size distribution curves of MOF-888, -889 and -890 derived from

Figure 3.17 CO2 (red), CH4 (blue) and N2 (green) isotherms for MOF-889 at 298 K Filled and open symbols represent adsorption and desorption branches, respectively The connecting curves are guides for the eye 101

Figure 3.18 CO2 (red), CH4 (blue) and N2 (green) isotherms for MOF-890 at 298 K Filled and open symbols represent adsorption and desorption branches, respectively The connecting curves are guides for the eye 102

Figure 3.19 The isosteric heat of adsorption of CO2 (solid lines) and N2 (dashed lines) for MOF-888 (green), -889 (blue), and -890 (red) 103

Figure 3.20 The isosteric heat of adsorption of CO2 (solid lines) and CH4 (dashed lines) for MOF-888 (green), -889 (blue), and -890 (red) 103

Figure 3.21 A binary mixture of CO2/N2 (A) or CO2/CH4 (B) is flown through a fixed bed

of MOF-890 The breakthrough time is indicated by the dashed line 105

Figure 3.22 ORTEP representation of the asymmetric unit of MOF-892 displayed with 50%

probability Atom colors: Zr, cyan; N, blue; O, red; H, white; and C, grey 111

Figure 3.23 Crystal structure of MOF-892 (A) Linking of rectangular H2CPB 4- and trigonal-prismatic Zr6O4(OH)4(CH3CO2)6(CO2)6 SBUs results in (B) MOF-892 (C) The

structure of MOF-892 adopts the stp topology Atom colors: Zr, blue polyhedral; C and O

atoms, black and red spheres, respectively; and acetate C and O atoms, gray and pink spheres, respectively; all H atoms are omitted for clarity 112

Figure 3.24 ORTEP representation of the asymmetric unit of MOF-893 displayed with 30%

probability Atom colors: Zr, cyan; O, red; H, white; and C, grey 114

Figure 3.25 The different connectivity among linker and metal nodes in MOF-893 Atom

colors: Zr, blue; O, red; and C, grey Hydrogen atom are omitted 114

Figure 3.26 Crystal structure of MOF-893 (A) Linking of rectangular H2CPB 4- and distorted cube-shaped Zr6O4(OH)5(CH3CO2)3(CO2)8 SBUs results in (B) MOF-893 (C) The

structure of MOF-893 adopts the new hfp topology Atom colors: Zr, blue polyhedra; C and

O atoms, black and red spheres, respectively; and acetate C and O atoms, gray and pink spheres, respectively; all H atoms are omitted for clarity 115

Figure 3.27 Comparison of the simulated (black) PXRD pattern from the single crystal data

with the experimental as-synthesized (red) and activated (blue) PXRD patterns of MOF-892 116

Figure 3.28 Comparison of simulated (black) PXRD pattern from the single crystal data

with the experimental as-synthesized (red) and activated (blue) PXRD patterns of MOF-893 117

Figure 3.29 TGA traces of activated MOF-892 at a heating rate of 5 °C min-1 under air flow 118

Figure 3.30 TGA traces of activated MOF-893 at a heating rate of 5 °C min-1 under air flow 118

Figure 3.31 FT-IR of H6CPB (black), activated MOF-892 (red) and MOF-893 (blue) 119

Figure 3.32 N2 isotherms of MOF-892 (red) and MOF-893 (blue) at 77 K Filled and open symbols represent adsorption and desorption branches, respectively The connecting curves are guides for the eye 120

Figure 3.33 CO2 isotherms for MOF-892 at 273 (red), 283 (green), and 298 K (blue) Filled and open symbols represent adsorption and desorption branches, respectively The connecting curves are guides for the eye 121

Figure 3.34 CO2 isotherms for MOF-893 at 273 (red), 283 (green), and 298 K (blue) Filled and open symbols represent adsorption and desorption branches, respectively The connecting curves are guides for the eye 122

Figure 3.35 The isosteric heat of adsorption of CO2 for MOF-892 (red) and MOF-893 (blue) 122

Figure 3.36 Investigation of catalytic activity for MOF-892 in the cycloaddition of styrene

oxide and CO2 124

Figure 3.37 Catalyst filtration experiment of MOF-892 for the cycloaddition reaction of

styrene oxide with CO2 128

Figure 3.38 Catalyst filtration experiment of MOF-893 for the cycloaddition reaction of

styrene oxide with CO2 129

Figure 3.39 Recycling experiments of MOF-892 for the cycloaddition reaction of styrene

oxide with CO2 130

Figure 3.40 Recycling experiments of MOF-893 for the cycloaddition reaction of styrene

oxide with CO2 130

Figure 3.41 PXRD patterns of calculated MOF-892 from the single crystal data (black),

experimental as-synthesized (red), activated (blue), after 5th time recycling and reusing of MOF-892 under the same reaction conditions (green) 135

Figure 3.42 PXRD patterns of calculated MOF-893 from the single crystal data (black),

experimental as-synthesized (red), activated (blue), after 5th time recycling and reusing of MOF-893 under the same reaction conditions (green) 135

Figure 3.43 FT-IR of an activated MOF-892 (red) and after 6th time recycling and reusing

of MOF-892 (blue) 136

Figure 3.44 FT-IR of an activated MOF-893 (red) and after 5th time recycling and reusing

Figure 3.47 FT-IR spectra of adsorbed pyridine for fresh (red) and recycled (blue)

MOF-892 catalysts (B): Brønsted sites, (L): Lewis sites 139

Figure 3.48 FT-IR spectra of adsorbed pyridine for fresh (red) and recycled (blue)

MOF-893 catalysts (B): Brønsted sites, (L): Lewis sites 140

Figure 3.49 Comparison of as-synthesized (black), activated (red) PXRD pattern of

MOF-892 with the as-synthesized (blue), activated (green) PXRD pattern of MOF-MOF-892 collected after esterification 141

Figure 3.50 1H NMR analysis of Me-MOF-892 post-digestion 142

Figure 3.51 FT-IR of MOF-892 (red) and Me-MOF-892 (blue) 143 Figure 3.52 TGA traces of parent MOF-892 (red) and Me-MOF-892 (blue) at a heating rate

of 5 °C min-1 under air flow 143

LIST OF SCHEMES AND TABLES Scheme 1.1 Reaction of CO2 with Monoethanolamine (MEA) to give a carbamate

ions 36

Scheme 1.2 Synthesis of cyclic carbonate from epoxide, olefin, 1,2-diol, and cyclic ketal 44

Scheme 1.3 Possible products from the reaction of CO2 and epoxides: cyclic carbonates (a), polycarbonates (b) and polycarbonate containing ether linkages (c) 46

Scheme 1.4 Mechanism of the formation of carbonates from propylene oxide and CO2 involving a metal complex and a nucleophile The nucleophile may originate from the metal complex or from a co-catalyst 47

Scheme 1.5 Schematic representation of synthesis of cyclic carbonates from olefins and CO2 using TBAB co-catalyst 50

Scheme 1.6 A proposed mechanism for the direct synthesis of styrene carbonate from styrene and CO2 in TBAB with TBHP 51

Table 1.1 MOF catalysts for the cycloaddition of CO2 to epoxides 52

Scheme 2.1 Cycloaddition of epoxides and CO2 under model condition 78

Scheme 2.2 Oxidative carboxylation of styrene and CO2 79

Scheme 3.1 Synthetic route to MOF-888, -889, and -890 from H6CPB 83

Scheme 3.2 Synthetic route to H6CPB linker 83

Table 3.1 Characterizations of compound 2, 3, 4 85

Table 3.2 Structural information of MOF-888, -889, and -890 86

Table 3.3 Summary of the surface area (SA), pore size distributions (PSD) and pore diameter of MOFs 99

Table 3.4 Surface area, thermodynamic CO2, N2, and CH4 uptake capacity at 298 K for MOF-888, -889, and -890 100

Table 3.5 Isosteric heat of CO2 adsorption (Qst) and CO2/N2 & CO2/CH4 selectivity for MOF-888, -889, and -890 104

Table 3.6 Dynamic CO2 uptake capacity for MOF-890 106

Table 3.7 Comparison of the CO2 separation properties of MOF-890 with other CO2

absorbents 107

Scheme 3.3 Synthetic route to MOF-892 and -893 from H6CPB 109

Table 3.8 Structural information of MOF-892 and -893 110 Table 3.9 Optimization of reaction conditions for cycloaddition of CO2 with styrene oxide catalyzed by MOF-892 and MOF-893a 125

Table 3.10 Optimization of reaction for cycloaddition of CO2 with various epoxides and base co-catalysts catalyzed by MOF-892a 127

Table 3.11 Comparison of catalytic performance of representative MOF catalysts

toward their porosities and CO2 adsorptions at 298 Ka 132

Table 3.12 Comparison of catalytic performance of representative MOF catalysts

toward their porosities and CO2 adsorptions at 298 Ka 134

Table 3.13 Comparative study of MOF-892 and Me-MOF-892a 144

Table 3.14 One-pot synthesis of styrene carbonate from styrene and CO2 catalyzed

by MOF-892 with the oxidant tert-butyl hydroperoxide (TBHP) a and comparative studies 146

ASSURANCE

I declare that my work in this dissertation, entitled “Synthesis of Hexacarboxylic

Acid Linker based Metal-Organic Frameworks for Applications in Selective

CO 2 Capture and Chemical Fixation of CO 2”is assured to be my experimentally scientific works without any plagiarism from other published reports Our results in this research are genuine and trustworthy Partial literature in this dissertation could

be adopted and rewritten from peer-review papers and books which were carefully cited in the reference section Finally, I am entirely responsible for the contents of

my dissertation

Ho Chi Minh City, December 2018

Nguyen Thi Kieu Phuong

ACKNOWLEDGMENTS

First of all, I especially thank my advisors Assoc Prof Nguyen Thai Hoang and Assoc Prof Ton That Quang for enabling and supporting my scientific research at the beginning of my academic studies at University of Science I am eternally thankful for the encouragement and guidance that I received from my advisors Prof Omar M Yaghi is gratefully acknowledged for founding MANAR and his continuous support of global science activities

I owe my deepest gratitude to Visiting Prof Dr Hiroyasu Furukawa for his mentorship, guidance and intellectual inspiration His profound understanding in chemistry and innovative advices in research lead me to improve my foundation and further my scientific works His patience and encouragement help me to overcome many crisis situations Without his precious mentorship, it would not be possible to conduct this research and have this dissertation

I would like to thank Kyle E Cordova for his useful discussion His mentorship allow

me to explore my interests, to gain confidence, and to learn substantial skills that are crucial for my research His support was instrumental in the completion of this dissertation

I also would like to thank Prof Jaheon Kim, Dr Felipe Gandara, and Dr Christopher

A Trickett for the valuable inputs towards the crystallographic work and synchrotron single-crystal X-ray diffraction Without their helps, our studies could not be accomplished

Besides, I am grateful to my college, Ms Nguyen Thi Diem Huong, for her intellectual contributions on our studies She helped me not only on academic study but also doing research during my graduate school I thank Mr Pham Quang Hung for his friendship and reliable discussion I also thank my students, Ms Tran Bach

Nhu Y and Mr Nguyen Ngoc Hung for their contributions and valuable assistance in our work

I appreciate to former MANAR members, especially Dr Phan Thi Phuong Anh, Dr

Le Thanh Dung, Dr Nguyen Thi Le Anh, Dr Le Viet Hai, Dr Nguyen Thi Tuyet Nhung, Mr Nguyen Thanh Binh, and Ms Lo Nu Hoang Tien for their advices and supports I also thank to INOMAR members: Assoc Prof Phan Bach Thang, Prof Hoang Dzung, Dr Nguyen Lac Ha, Dr Tu Ngoc Thach, Dr Doan Le Hoang Tan,

Ms Nguyen Ho Thuy Linh, and my students, Ms Tran Thi Thao Huong, and Ms Nguyen Thi Thao Nhu for their helps Dr Le Thi So Nhu and Dr Tran Hoang Phuong are acknowledged to their encouragements

Lastly, I deeply thank my parents, my family, and my close friends for always supporting and believing me throughout my life

Abstract of the Dissertation

The Synthesis of Hexacarboxylic Acid Linker-based Metal-Organic Frameworks for Applications in Selective CO2 Capture and Chemical

Fixation of CO2

Metal-Organic Frameworks (MOFs) are new hybrid materials which are

constructed from linking inorganic and organic units via strong bonds to create

extended crystalline structures The exceptional features of high surface area, diversity of topological structures, and variable functionalities have led MOFs to exceed those of traditional porous materials such as zeolites and carbons Specifically, the chemistry of MOFs has been developed to the point that one can rationally and systematically modulate the interplay between the MOF structure and the desired properties Thus, MOFs become attractive materials for many related energy applications The work herein describes a preparation of an organic linker and subsequently synthesis of novel series of MOFs for (1) adsorbents for selectively

heterogeneous catalysts for chemical conversion of CO2

were additionally given in the field of developing new CO2 adsorbents and

Chapter 2 is an experimental part dedicating to the synthesis and analytical

corresponding MOFs (termed MOF-888, -889, -890, -892, and -893) The instrumental experiments, structural elucidations, and gas adsorption measurements were described in this section In the context of CO2 separation application, the selective CO2 adsorption and isosteric heat of adsorption of MOF were reported,

from binary gas mixtures of CO2/N2 and CO2/CH4 In the light of the application in

cycloaddition of CO2 to epoxide and olefin catalyzed by MOFs leading to cyclic carbonate was provided Additionally, the recycling experiments, methyl esterification of free carboxylic acid, and the purified procedure of carbonate products were described in this chapter

Chapter 3 reports the results and discussion of the syntheses, characterizations

-890, -892, and -893 Based on the MOF’s structural features, these members are accordingly divided into two sections, including (i) adsorbents for selective CO2

capture and (i) heterogeneous catalysts for chemical fixation of CO2 In first section,

MOF-890 showed the highest CO2 capture in the group MOF-890 was also proved to effectively separate CO2 from binary gas mixtures containing N2 or CH4 by breakthrough experiments The second section discuss the results of two novel zirconium-based MOFs, MOF-892 and -893, in which their structural features are highlighted with Lewis and Brønsted sites acting as highly active catalytic sites led

exhibits the highest catalytic activity among the series and, interestingly, shows a good catalytic activity in a one-pot oxidative carboxylation of styrene and CO2 which has been rarely studied in MOF platforms

Conclusion and outlook is a final section discussing the prospective of MOFs

in the contexts of the selective CO2 adsorption section and the heterogeneous chemical conversion of CO2 leading to the formation of cyclic carbonates

Chapter One

Introduction of Metal-Organic Frameworks for Applications in Selective

CO2 Capture and Chemical Fixation of CO2

1.1 Introduction of Metal-Organic Framework (MOF)

1.1.1 Metal-Organic Framework (MOF) and Reticular Chemistry

MOFs are constructed via strong bonds between metal-containing clusters and

Metal-containing and organic units in the MOF structure can be simplified in

chemistry, termed reticular chemistry, is developed by the combination of a given

of reticular chemistry, MOFs can be designed based on versatile choices of inorganic/organic building units and functionalities in order to obtain desirable materials.1 Therefore, MOFs become one of the most interest in material science, which their features have more advantages than other traditional porous materials, such as zeolites, carbon-based adsorbents, and other hybrid materials

The inorganic SBUs are metal atoms or finite polyatomic clusters containing two or more metal atoms or infinite unit such as one-periodic rod of atoms (Figure

1.1 & 1.2) Metal-containing SBUs are in-situ formed at the time of synthesis using

specific conditions (e.g solvent, temperature, pH) The shape of SBU is defined by points of extension where they connect to organic components to create geometrical diversity of polygon, polyhedron, or rod.3,4 On the other hand, organic linkers are defined by the tailored shapes from ditopic, tritopic or polytopic preformation (Figure 1.3) Since the organic linkers remain intact and their geometry is preserved throughout the assembly process, MOF is able to be predicted the underlying topology of the framework structure.3,4

Figure 1.1 Metal-containing clusters and their corresponding SBUs Atom colors:

metal, blue polyhedra; C, black; O, red

Figure 1.2 Rods with points of extension forming (A) zigzag ladder,5 (B) infinite,6

(C) twisted ladder.5 Atom colors: metal, blue polyhedra; C, black; O, red

Figure 1.3 Organic linkers (top) and their corresponding SBUs (bottom) Atom

colors: C, black; O, red

MOF-5, a well-known porous MOF (Figure 1.4A), constructed from an octahedral inorganic SBU Zn4O(−CO2)6 with six points of extension (carboxylate C atoms) and terephthalate ligand (ditopic) The resulting extended framework has a

simple cubic net with six-coordinated (6-c) vertices adopted pcu topology.7 Other

four points of extension arranged at the vertices of a square connect to a tricarboxylate ligand with a triangle 3-c branch point The underlying net is accordingly a (3,4)-

coordinated net with the symbol tbo.8

Figure 1.4 (A) MOF-5 showing the abstraction of the Zn4O(−CO2)6 SBU as an octahedron, the ditopic terephthalate linker as a linear rod, and their assembly into

wheel abstracted as a square, the tritopic linker as a triangle, and their combination

to form the tbo net shown in augmented form tbo-a Atom colors: Zn (for MOF-5)

and Cu (for HKUST-1), blue polyhedra; C, black; O, red; all H atoms are omitted for clarity The large yellow, orange and pink spheres represent the largest sphere that would occupy the cavity All hydrogen atoms are omitted for clarity

Inorganic and organic constituents of MOFs can be varied in their geometric shape, pore/channel size, chemical composition, and functionality to produce a versatile class of porous crystalline solids with a diversity of network topologies (Figure 1.5)

Figure 1.5 Representative binodal nets in reticular chemistry.9

In particular, whenever a certain MOF of given topology for a certain combination of shapes has been synthesized, it is possible to obtain a suite of materials with the same topology but different lengths and/or functionalities of organic SBUs Such series of compounds are called isoreticular.10 For instance, there

is a famous isoreticular MOF structures of MOF-5 with pcu net, one of the smallest

is Zn4O(fumarate)3,11 and one of the largest is IRMOF-16 [Zn4O(TPDC)3, TPDC2– = terphenyl-4,4′′-dicarboxylate].10 In this expansion, the unit cell edge is doubled and its volume is increased of 7.8 (Figure 1.6)

Figure 1.6 The isoreticular (maintaining same topology) expansion of archetypical

MOFs resulting from discrete inorganic SBUs combined with ditopic organic linkers

to obtain MOFs in a pcu net Atom colors: Zn, blue polyhedra; C, black; O, red The

yellow spheres are placed in the structure to indicate space in the cage

1.1.2 Introduction of Hexacarboxylic-Acid-based Organic Building and Inorganic Building Units

MOF’s structures are versatile to be designed based on geometrically influenced choices of inorganic and organic building units One particular direction that has received attention in MOF synthesis is the use of multicarboxylate organic linkers, which has afforded new MOF materials with unique structural features and interesting intrinsic properties.12 Specifically, when multicarboxylate linkers are employed, the metrics of the pore size and shape as well as the pore surface have been shown to be modifiable to optimize for gas storage and separation applications Hexacarboxylic acid linkers can take a variety of topologies, shapes and gas

properties In graph theory, the tree nets whose topologies are without rings and

overall symmetric shapes (trees in graph theory) are planar hexagon, octahedron, or

trigonal prism (Figure 1.7a-f) The star net with have a single 6-c vertex is obtained

from C6 axes resulting of a highly symmetrical hexagonal shape (Figure 1.7g).13

Figure 1.7 Topologies and shapes for hexatopic linkers: (a−c) trigonal prisms, (d, e)

octahedra, and (f-g) hexagon

An interesting (4,6)-connected ntt topology which is constructed from a

hexagonal 6-c vertex of hexatopic organic unit connecting to a square planar 4-c of inorganic SBU has been demonstrated to afford a series of highest BET surface area materials (Figure 1.8) For example, a series of isoreticular MOFs constructed from

an elongated hexatopic linker, demonstrated the highest BET surface for any known porous material H6TTEI linker was used to crystalize into NU-100 [Cu3(TTEI)] which was further proven the permanent porosity by BET surface area of 6143 m2/g.14

BET surface area of 5000 m2/g, and such high porosity leads to the high total H2

NU-110 is 7140 m2/g, which is the highest value in any porous solid (Figure 1.9).16

Figure 1.8 Schematic of the crystal structure of a NU-111, -100, and -110 from left

to right, respectively Color code: Cu, blue; C, black; O, red All H atoms are omitted for clarity The yellow and orange spheres are placed in the structure to indicate space

in the cage

Figure 1.9 Crystal structure of NU-110E Hexacarboxylic linker (H6L) connects to

a Zr6 SBU forming the three-dimensional structure adopting she topology Color

code: Cu, blue; C, black; O, red All H atoms are omitted for clarity The yellow and orange spheres are placed in the structure to indicate space in the cage

Hexaarylbenzene derivatives have attracted a lot of research interest because

of their unpredictable geometry and significant role in generating liquid crystalline materials,17 molecular-scale devices,18 and molecular receptors.19 A large part of reports covering on hexaarylbenzene derivatives emphasis on the role of star-shaped topology of these derivatives in formation of thin amorphous films with relatively high charge-transfer properties in organic devices.20 Furthermore, the star-shaped hexaarylbenzene macromolecules have been used as a template to generate highly porous macrocycles, thus, the porous structures enhance the guest binding for detection, purification, transportation, and drug-delivery purposes High π-conjugated in hexameric structures result in good fluorescence emission, which proceed these type of molecules as fluorogenic chemosensors through noncovalent interactions like π−π, metal−π, coordination, van der Waals, and H-bond interactions Therefore, the sterically strained scaffold of hexaarylbezene has been widely chosen

to design and synthesize large dendrimeric structures, which results in formation of big voids within the molecule so as to use these dendrimers for adsorption of gaseous

as well as solvent molecules.21

Like MOFs, covalent organic frameworks (COFs) are also crystalline porous materials with periodic ordering of organic building blocks without any metal units Being nonplanar and bulky in nature, hexaarylbenzene-based COFs exhibit good prospects in wide ranges application, such as gas storage, photoconductive devices, energy conversion, and heterogeneous catalysis For example, a HPB COF (Figure 1.10A),22 with a small triangular pore type, high π-column density, and π-cloud delocalization, which facilitates charge transport through the π-channels Another

of CO2 (20 wt %) and CH4 (2.3 wt %) at 273 K (1 atm)

Figure 1.10 Hexaarylbenzene based-covalent organic framework

In MOF chemistry, the geometry and coordination number (points of extension) of the selected SBUs and organic linkers dictate the topological and structural features of the resulting frameworks Accordingly, it is possible to prepare MOFs with the desired structural features for a given application In the context of catalytic conversions for instance, materials can be constructed with large pore apertures and a high density of accessible metal sites,24 by combining multiple active

linkers26 or inside their pores.27

Among the different metal units that have been employed in the preparation

of MOFs, zirconium has attracted much attention in recent years Many of the MOFs have been proven to be stable in water and low pH environments, making them suitable for applications in multiple fields.28 Hence, following the report of UiO-66,29

Zr-which has a 12-connected fcu topology, a number of new related materials have been

published with increasing structural complexity, which arises from the use of different, multitopic organic linkers as well as from structural modifications in the inorganic SBUs.30 These modifications may appear in the form of connectivity defects or as changes in the number or disposition of the SBU’s points of extension.31

While most of the known zirconium MOFs are built from a related inorganic SBU consisting of six octahedrally disposed zirconium atoms joined by 83-oxygen atoms (either O2- or OH-), the number of connection points for a given SBU can be modified

to be 12, 10, 8, or 6 depending on the framework topology (Figure 1.11).32

Figure 1.11 Inorganic SBUs of various coordination numbers are known in the

family of the zirconium-based MOFs Atom colors: Zr, blue polyhedra; C, black; O, red All H atoms are omitted for clarity

Consequently, the structural variability of zirconium MOFs has significantly increased in recent years, and a large number of new materials have been reported being formed by the combination of related Zr6 based SBUs along with various multitopic organic linkers, producing networks with binodal topologies, including

12,4-c (ftw, ith),33 8,4-c (csq, flu, sqc),34 6,4-c (she),35 or 6,3-c (spn),36 (Figure 1.12) among others

Figure 1.12 Representative binodal nets in reticular chemistry adopted in zirconium

MOFs

1.2 Carbon Dioxide Capture and Separation

is one of the most environmental concerns that proceed the global climate change Indeed, the concentration of CO2 atmospheric has risen sharply from the preindustrial level of 280 parts per million (ppm) to more than 400 ppm in 2017 (Figure 1.13A)

In fact, anthropogenic greenhouse gas emissions since the pre-industrial era have driven large increases in the atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) (Figure 1.13B) As a carbon-neutral economy may remain elusive for years, an urgent demand is required to mitigate the environmental impact of the combustion of carbon-based fuels, such as coal, oil, and

(CCS) technologies are demonstrated to efficient capture of CO2 from existing emission sources due to abilities reducing by 80–90% of CO2 emissions.37

Figure 1.13 (A) Atmospheric CO2 concentration (at Mauna Loa Observatory),

Atmospheric concentrations of the greenhouse gases carbon dioxide (CO2, green),

(dots) and from direct atmospheric measurements (lines)

CO2 capture is most effective when large quantities of CO2 are generated site, such as in power stations and methane-reforming plants Capturing CO2 from post-combustion flue gas mixtures with carbon dioxide concentrations of around 12–14% is one of the capable technology in the current development In addition, pre-combustion and oxy-combustion capture are other options for concentrated CO2

on-capture to achieve higher efficiency Pre-combustion strategies adsorb CO2 from gas

mixtures of fuels before the combustion process, generating hydrogen that is delivered and consumed at sites Oxy-fuel combustion utilizes pure O2 instead of air for combustion to obtain concentrated CO2 After CO2 is selective captured, the second path is the sequestration and storage of CO2 in subsurface geologic formations, at 100–150 bar in depleted oil and gas fields at around 800–1000 m below the surface,38 where no release into the atmosphere occur over a relatively long period

of time So far, the most challenging step is the CO2 capture, which requires selective and rapid processes with minimal energy input (Figure 1.14)

Figure 1.14 Three main types of CO2 capture in the current technology

Materials used for CO2 capture in coal- and gas-fired power plants has prompted the study of several classes of materials to date The development of materials requires the consideration of numerous performance parameters, which can

be varied depending on the type of CO2 capture and the specific configuration of the

is permanent selectivity toward CO2 gas, which CO2 component of the flue gas/natural gas is completely removed for subsequent sequestration The affinity of the material toward CO2 is also a major consideration for optimizing the energy penalty of capture Indeed, if the interaction is too strong, a high energy is required for desorption of the captured CO2 On the other hand, weak interactions could lower

of the mixture gas Furthermore, the material should exhibit a high stability under the capture and regeneration conditions, thus can be exploited for the lifetime of the power plant Owing to the large quantities of CO2 captured, the materials should take

up high density of CO2, such that the volume of the adsorbent bed could be minimized

The most widely approach is using aqueous amine solutions (e.g monoethanol amine, MEA) which has been used in the natural gas industry for more than 60 years

as they are well developed, easy to handle, relatively inexpensive and exhibit high gas solubility and selectivity (Scheme 1.1).39 Aqueous basic solvents selectively

regenerated then by heating the solution at temperatures well above 100 oC.However, amine solutions are also corrosive toward the contained vessels, and this issue is usually prevented by the addition of corrosion inhibitors or by limiting the concentration of the alkanolamine species to below 40 wt% Hence, research progress

is in development of improved solvents that require less heating for regeneration and are able to absorb more CO2

Scheme 1.1 Reaction of CO2 with Monoethanolamine (MEA) to give a carbamate

ions

Solid porous adsorbents, which could have much lower heat capacities, are presented a promising strategy for reducing the regeneration energy penalty The main types of conventional solid adsorbents encompass zeolites, porous carbon and porous silica,40all of which show considerable limitations that need to be addressed The relatively low internal surface area of zeolites minimizes their capacity for carbon dioxide under flue gas conditions In contrast, activated carbons generally show very low uptakes at ambient pressure (post-combustion conditions) and are therefore suitable only for pre-combustion capture (high pressure)

1.3 MOFs for Selective CO 2 Capture

In particular, some MOFs have been demonstrated to outperform commercial porous carbons and zeolites In recent years, extensive studies of MOFs have been developed to address the CO2 problem Herein we will focus on MOFs for CO2

adsorption at low pressures (≤1 bar), the condition relevant to CO2 capture from

moment, any moieties that are capable of inducing polarizability (such as, based groups, open metal sites,…) are thus highly desirable for functionality of MOF’s surface In addition, non-polar interactions such as trapping carbon dioxide

amine-in a confamine-ined space through suitable pore sizes, or chemisorption processes with amine functionalization, are often used to enhance the absorbed performance

1.3.1 MOFs with Open Metal Sites

Metal clusters in MOFs are coordinatively saturated but in some MOFs, some

of the metal atoms are partially coordinated by guest solvent molecules When these coordinated solvent molecules are excluded by heating the material, unsaturated or open metal sites occur within the MOF pores The resulting open metal sites act as Lewis acidic sites that strongly polarize gas adsorptives, and thus are favorable for

H2 and CO2 storage in MOF and increasing the isosteric heat of adsorption (Qst) of

H2 and CO2 Moreover, such a polarized affinity provides a great opportunity for synthetic functionalization by grafting functional groups onto unsaturated metal sites

post-A series of isostructural frameworks M-MOF-74, [M2(DOT)(H2O)2], where M=Zn, Ni, Co, Mg, Mn and DOT is dioxidoterephthalate, constructed from infinite rods {M3[(-O)3(-CO2)3]}∞ forming 1D-hexagonal channels ca 12 Å with adopting

etb topology (Figure 1.15) Those isoreticular structures were shown to have high

thus reveal high CO2 uptake especially at low pressures (0.1–0.2 bar), which is the

pressure region of interest in flue gas separation Also, they exhibited high Qst values for CO2 (37–47 kJ mol-1), which suggests preferential adsorption of CO2 on open metal sites.41

Figure 1.15 Crystal structure of M-MOF-74 DOT link is joined by an infinite metal

oxide SBU to make the three-dimensional structure with one-dimensional hexagonal

channels and adopting the etb topology Atom colors: metal, blue polyhedra; C,

black; O, red All H atoms are omitted for clarity

1.3.2 MOFs Functionalized by Nitrogen Bases

MOF functionalized with amine-based groups have been intensively studied for their CO2 adsorption properties The dispersion and electrostatic forces resulting from the interaction of the quadrupole moment of CO2 with localized dipoles generated by heteroatom incorporation are typically responsible for the enhanced

CO2 adsorption In some cases, acid-base type interactions between the lone-pair of

Conventionally, three major categories of nitrogen-functionalized MOF have been prepared: heterocycle (i.e., pyridine) derivatives, aromatic amine (i.e., aniline) derivatives, and alkylamine (i.e., ethylenediamine) bearing frameworks

The incorporation of the heterocycle generally improves capacity only

ca 5.8 wt% at 298 K and 0.15 bar, with a corresponding isosteric heat of adsorption

at zero-coverage of -45 kJ/mol (Figure 1.16) The large initial isosteric heat is likely partially attributable to the presence of an aromatic amine However, the effects of