Luận án tiến sĩ Hóa học: Synthesis and functionalization of acidic metalorganic frameworks for catalysis and adsorption

TÓM TẮT NỘI DUNG LUẬN ÁN s* Đối tượng và phương pháp nghiên cứu - MOF có số phối trí 6 và 12 được hình thành bởi tâm kim doại zirconium/ hafnium và cầu nối hữu cơ dicarboxylic acid/ tric

VIET NAM NATIONAL UNIVERSITY - HO CHI MINH

UNIVERSITY OF SCIENCE

NGUYEN HO THUY LINH

SYNTHESIS AND FUNCTIONALIZATION OF ACIDIC

METAL-ORGANIC FRAMEWORKS FOR CATALYSIS AND ADSORPTION

PHD THESIS OF CHEMISTRY

HOCHIMINH CITY — 2023

VIETNAM NATIONAL UNIVERSITY — HO CHI MINH CITY

UNIVERSITY OF SCIENCE

NGUYEN HO THUY LINH

SYNTHESIS AND FUNCTIONALIZATION OF ACIDIC

METAL-ORGANIC FRAMEWORKS FOR

CATALYSIS AND ADSORPTION

Specialty: Organic chemistry

Code: 9440114

Reviewer 1: Assoc Prof PhD Nguyen Van Cuong

Reviewer 2: Assoc Prof PhD Nguyen Huu Hieu

Reviewer 3: Assoc Prof PhD Nguyen Thai Hoang

Independent reviewer 1: Exempt

Independent reviewer 2: Exempt

SUPERVISOR

1 Assoc Prof PhD Tran Hoang Phuong

2 PhD Doan Le Hoang Tan

HOCHIMINH CITY — 2023

I hereby declare that this is my research work under the guidance of Assoc.Prof PhD Tran Hoang Phuong and PhD Doan Le Hoang Tan The data cited areoriginal, the results in the thesis are honest, and they have never been published in any

previous application for a higher degree

Ho Chi Minh City, June 2023

Nguyen Ho Thuy Linh

First, I am incredibly grateful for Assoc Prof PhD Tran Hoang Phuong andPhD Doan Le Hoang Tan provided dedicated and thoughtful guidance to help mewith the research orientation, implementation process, and thesis editing

I would like to thank the Board of Directors of the Center for InnovativeMaterials & Architecture INOMAR) and the Board of Directors of the Department ofChemistry, University of Natural Sciences, Vietnam National University, Ho Chi

Minh City, for creating all conditions to help me study, research, and complete the

With all my deep gratitude, I would like to dedicate to my Family, Parents,who have guided, encouraged, loved, and deeply sympathized

Thank you very much!

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TRANG THÔNG TIN LUẬN ÁN

Tên đề tài luận án: “Tổng hợp và chức năng hóa vật liệu khung hữu cơ-kim loại có

tính acid cho ứng dụng làm xúc tác và hấp phụ”

Ngành: Hóa hữu cơ

Mã số: 9440114

Họ tên nghiên cứu sinh: NGUYÊN HO THUY LINH

Khóa đào tạo: K29/2019

Người hướng dẫn khoa học: 1 PGS.TS Tran Hoàng Phương

2 TS Đoàn Lê Hoàng Tân

Cơ sở đào tạo: Trường Đại học Khoa học Tự nhiên, ĐHQG.HCM

1 TÓM TẮT NỘI DUNG LUẬN ÁN

s* Đối tượng và phương pháp nghiên cứu

- MOF có số phối trí 6 và 12 được hình thành bởi tâm kim doại zirconium/ hafnium và

cầu nối hữu cơ dicarboxylic acid/ tricarboxylic acid là vật liệu tiềm năng trong lĩnh vực xúc

tác và hấp phụ bởi diện tích lỗ xốp, độ bền nhiệt, độ bền hóa học cao và tâm hoạt tính Lewis

acid/ Brønsted acid.

- Phuong pháp nhiệt dung môi và phương pháp vi sóng được sử dụng nhằm tạo ra

khuyết tật cầu trúc cho Zr-MOF và Hf-MOF thông qua sự thay đổi về tốc độ và thời gian kết

kinh Ngoài ra, chức năng hóa nhóm sulfuric acid băng phương pháp ngâm nhằm tạo ra tâm

Brønsted acid trên cụm kim loại Hf-MOF có số phối trí 6.

- _ Hoạt động xúc tác của MOF được khảo sát trong một số phản ứng ngưng tụ đóngvòng và phản ứng cộng thé để tong hợp khung quinazolinone và benzoxazole bằng phương

pháp khuấy từ gia nhiệt và vi sóng Hf-MOF được chức năng hóa nhóm sulfuric acid được

xem xét trong phan ứng khử nước dé tổng hợp 5-HME.

- Kha năng hấp phụ của MOF được nghiên cứu trên hợp chất màu hữu cơ methylene xanh, methyl cam va indole bởi thí nghiệm đường cong hap phụ, động học hap phụ và nhiệt động học hấp phụ.

s* Thiết bị và phương pháp thực nghiệm:

-_ Trong luận án, các phương pháp phân tích cấu trúc và tính chất vật liệu đã được sử

dụng như nhiễu xạ tia X dạng bột, quang pho hồng ngoại, nhiệt trọng lượng vi sai, hấp phụ

khí nitrogen 77K, kính hién vi điện tử | quét và chuẩn độ điện thế acid-base.

- Ngoài ra, các phương pháp sắc ký khí ghép các đầu dò khối phổ, ion hóa ngọn lửa, quang phô tử ngoại khả kiến, sắc ký lỏng hiệu năng cao được sử dụng nhằm phân tích thành phan và định lượng sản pham trong phần nghiên cứu ứng dụng xúc tác và hấp phụ.

s* Kết quả và kết luận:

- ZMOE và Hf-MOF có số phối trí 6 và 12 đã được tổng hợp và phân tích cầu trúc

khuyết tật, tính chất xốp và acid Trong đó, Zr-BDC và Zr-NDC (số phối trí 12) được tông

hợp bằng phương pháp vi sóng cho thấy sự gia tăng diện tích bề mặt và kích thước lỗ xốp so với vật liệu được tổng hợp bằng phương pháp nhiệt dung môi Zr-BDC-MW có khả năng xúc tác cao hơn Zr-BDC-ST và một số xúc tác acid truyền thống trong phản ứng tổng hợp

quinazolinone nhờ vào sự gia tăng tâm hoạt động xúc tác và không gian lỗ xốp

- Giá tri pKa của Zr-BTC và Hf-BTC được xác định thông qua chuẩn độ điện thế và cho

thấy tính Brønsted acid cua Hf-MOF thì cao hơn Zr-MOF MOF có số phối trí 6 xúc tác hiệu quả hơn vât liệu có số phối trí 12 trong phản ứng tông hợp quinazolinone và benzoxazole

11

trong điều kiện không sử dụng dung môi Dưới sự hỗ trợ của vi sóng giúp rút ngắn thời gian

tong hợp nhưng vẫn duy trì hiệu suất phản ứng Phản ứng chuyên hóa glucose thành 5-HMF

trên vật liệu Hf-BTC-SOq cho thấy vai trò hỗ trợ của chat lỏng ion và tâm xúc tác Bronsted

acid của MOE trong giai đoạn đồng phân hóa và khử nước.

- MOF có số phối trí 12 bao gồm Zr-BDC, Hf-BDC và Zr-NDC được nghiên cứu hấp

phụ methyl xanh, methyl cam và indole Zr-NDC tổng hợp bởi phương pháp vi sóng có kha

năng hấp phụ methylene xanh và methyl cam cao hơn so với Zr-NDC được tổng hợp ở điều kiện nhiệt dung môi Độ bền của Zr-NDC trong vùng pH từ 1-14 ảnh hưởng đến khả năng hấp phụ của vật liệu Cơ chế hấp phụ vật lý cho phép vật liệu có thé giải hap và tái sử dụng

trên 5 lần mà không ảnh hưởng đáng ké đến hiệu suất hấp phụ Zr-BDC, Hf-BDC hấp phụ

hợp chat indole với lượng tải trên 150 m? g! và hiệu suất tải trên 80% Hệ vật liệu MOF

mang indole cho thấy hiệu quả bắt giữ ion fluoride ở nồng độ 1000 ppm sau 120 phút và có thé được theo đõi thông qua cơ chế bật va tắt huỳnh quang của hệ Zr-MOF và Hf-MOF tải

indole.

2 NHUNG KET QUA MOI CUA LUAN AN

- Nghién cứu tổng hop va phan tích cấu trúc khuyết tật, tính chat xốp, tinh Lewis acid,

Brønsted acid của Zr-MOF có số phối trí 12 bằng phương pháp nhiệt dung môi và vi sóng.

- _ Nghiên cứu tiên phong vê kha năng xúc tác của một số Zr-MOF và Hf-MOF có số phối trí 6 và 12 trong tông hop hợp chat khung quinazolinone, benzoxazole dưới điều kiện nhiệt truyền thống và vi sóng Phản ứng chuyên hóa glucose hay fructose thành 5-HMF dưới

xúc tác của MOF và chất lỏng ion.

- _ Nghiên cứu về kha năng hấp phụ phân tử hữu cơ màu nhuộm hay indole của Zr-MOF hướng đến ứng dụng vật liệu cho xử lý môi trường và y sinh.

3 CÁC ỨNG DỤNG/ KHẢ NĂNG ỨNG DỤNG TRONG THỰC TIỀN HAY NHỮNG VAN DE CON BO NGO CAN TIẾP TỤC NGHIÊN CỨU

- Các kết quả dat được của Luận án thể hiện được tính liên ngành gồm Vật liệu -Hóa học

— Môi trường.

- Mở rộng nghiên cứu về chất xúc tác Lewis acid MOF và Brønsted acid MOE cho phản

ứng tạo nôi C-N và ngưng tụ vòng.

- Nghiên cứu phản ứng chuyên hóa glucose tạo 5-HME trong dung môi chất lỏng ion có

thé được áp dụng dé tăng hiệu suất chuyền hóa sinh khối.

- Nghiên cứu vật liệu cảm biến fluoride từ sự hấp phụ các phân tử huỳnh quang trên nền vật liệu MOF có thé được phát triển dé áp dụng cho xử lý môi trường và y sinh.

1V

Supervisors: 1 Assoc Prof PhD Tran Hoang Phuong

2 PhD Doan Le Hoang Tan At: VNUHCM - University of Science

1 SUMMARY

“* Objective and methodology

- 6 and 12-coordinated MOFs, included zirconium/hafnium cluster and dicarboxylic

acid/ tricarboxylic acid linkers are potential materials in the field of catalysis and adsorption

by high specific surface area, thermal stability, high chemical stability and Lewis acid/

Brønsted acid sites.

- Solvothermal and microwave methods were used to create structural defects of

Zr-MOF and Hf-Zr-MOF through the change of speed and time crystallization In addition, the

immersion of 6-coordinated Hf-MOF with sulfuric acid group was created Brønsted acid sites

on the metal clusters.

- The catalytic activity of MOF has been considered in several cyclocondensation and

addition reactions for the synthesis of quinazolinone and benzoxazole by heating magnetic

stirring and microwave method The sulfuric-functionalized Hf-MOF was considered in the

dehydration reaction for the synthesis of 5-HMF.

- The adsorption capacity of MOF was studied on organic dyes methylene blue (MB),

methyl orange (MO), and indole (IND) through adsorption curves, adsorption kinetics, and

adsorption thermodynamics.

“* Experimental procedure

- In the thesis, the structure and properties and materials were analyzed by methods such

as powder X-ray diffraction, infrared spectroscopy, differential thermal gravimetric, 77K nitrogen gas adsorption, scanning electron microscope, and acid-base titration.

- In addition, gas chromatography methods coupled with mass spectrometry, and flame ionization detectors, ultraviolet-visible spectroscopy, high performance liquid chromatography are used for compositional analysis and product quantification in catalytic and adsorption applications studies.

“¢ Results and conclusions

- 6and 12 coordinated Zr-MOF and Hf-MOF were synthesized and analyzed for defect

structure, porosity, and acid properties Among them, 12-coordinated Zr-MOF (Zr-BDC and

Zr-NDC) were synthesized by microwave method, showed an increase in specific surface

area and pore size compared with materials synthesized by solvothermal Zr-BDC-MW has a

higher catalytic capacity than Zr-BDC-ST and some traditional acid catalysts in

quinazolinone synthesis based on the increase in catalytic activity sites and pore space.

- The pKa values of Zr-BTC and Hf-BTC were determined through potentiometric

titration and showed that the Brgnsted acid properties of Hf-MOF were higher than those of

Zr-MOF and Zr-BDC The 6-coordinated MOF is more effective than the 12-coordinated

V

MOF in the synthesis of quinazolinone and benzoxazole framework derivatives Using

microwave method and solvent-free, the synthesis time was shortened while maintaining the

reaction efficiency The reaction of converting glucose to 5-HMF on Hf-BTC-SO¿ material

shows the supporting role of ionic liquid and Brønsted acid MOF in isomerization and

dehydration stages.

- 12-coordinated MOFs, including Zr-BDC, Hf-BDC and Zr-NDC were studied for methylene blue, methyl orange, and indole adsorption Zr-NDC was synthesized by

microwave method, showed the higher adsorption capacity of MB and MO than that of

solvothermal The stability of Zr-NDC in the pH range of 1-14 affected the adsorption

capacity of the material The physical adsorption mechanism allows the material to be

desorbed and reused more than 5 times without affecting the significant adsorption

performance Zr-BDC and Hf-BDC adsorb indole with a loading capacity over 150 m? g

and a loading efficiency of over 80% The indole loaded on MOF system showed an effective

capture of fluoride ions at a concentration of 1000 ppm after 120 min and could be monitored

through the fluorescence on and off mechanism of the IND/MOF system.

2 NOVELTY OF THESIS

- Research on synthesis and characterization of defective 12-coordinated MOFs

(Zr-BDC and Zr-NDC) by solvothermal and microwave method.

- The-investigaton on the catalytic ability of 6- and 12-coordinated Zr-MOF and MOF in synthesizing quinazolinone, benzoxazole derivatives under traditional heat and microwave method The glucose or fructose conversion reaction to 5-HMF under sulfuric-

Hf-functionalized Hf-MOF and ionic liquid to enhance the isomerization and dehydration efficiency of monosaccharide.

- Study of adsorption of organic dyes or indole on 12-coordinated MOFs towards materials for environmental and biomedical applications.

3 APPLICATIONS/ APPLICABILITY/ PERSPECTIVE

The results of the thesis are obtained from the interdisciplinary research of Materials

-Chemistry - Environment.

- Broaden research on Lewis acid and Brønsted acid MOF catalysts for the C-N coupling and cyclocondensation reaction.

- The reaction to convert glucose into 5-HMF under catalysis of MOFs in ionic liquid

solvents can be applied to increase biomass conversion efficiency in synthesis of feedstock.

- Research on fluoride sensing materials from durable MOF materials can be developed

to increase detection at low concentrations and applications in environmental remediation and

biomedicine.

vi

2 LITERATURE REVIEW 2155 Ả 5

"N0 00i000i0o0/(9) 157 5

2.2 Acidic Of MOBS TH 10

2.2.1 Synthetic S{TAf€ØI€S - G1 1S TH TH HH HH key 12

2.2.2 Characterization techn1QU€S < s3 1193119 11 9 11g ng ng ng rưy 14

2.3 MOFs for catalysis apDDÏICAfIOH - ó- Ăn ng ng rưy 19

3.3.2 6-coordinated MOFs and incorporated MOE c5 2-csssssseeesse 34

3.4.Catalytic DTOD€TẨICS - 0 Án TH TH TH TH TT TH HH HH nh nà 35

3.4.1 Synthesis of QuinaZOliNONe - - 5 25 s31 nh nh ghng nnnư 35

3.4.2 Synthesis Of benZOXãZOÌ€ - - c 1H TH HH ng ng key 35

3.4.3 Synthesis of 5-HME G c 1n 1S TH TH HH HH key 36

3.S.AASOrptiOn PrOPe#@tie 177 36

3.5.1 Procedure of organic dye aSOTDfIOII - 5 Sc 1v svsseeereerereeree 36 3.5.2 Procedure of indole adSOTPION - - 5 11112119 vn ng rưy 38 4 RESULTS AND DISCUSSIƠN - Án HH TH HH HH HH ng nưệt 40 4.1 MOFs for catalysis applications G9 ry 40 4.1.1 12-coordinated MOIEsS - sgk 40 4.1.2 6-coordinated \MOES Gv HH TH HH HH 48 4.1.3 Incorporating sulfuric acid into Hf-BÏTC 5 5< £+s£+s+sexseeers 57 4.2 MOFs for adsorption applications - 5 «+ vn vnn ng Hng nnnưy 65 4.2.1 12-coordinated Zr-NDC - -.- s1 ng ng ng ng ry 65 4.2.2 12-coordinated Zr-BDC and Hf-BDC - 5 5S e*++vEsskksersexes 75 5 CONCLUSION AND OUTLOOK 5 5 1 1n ng ng ng ri, 85 S.1 e0 85

909 86

9585)45)0I0) S111 4d 87

LIST OF PUBLICA TIONS Ghi r 98 APPENDIX 022 e 99

I8 0m3): 99

NMR data and Spectra NA e 110

List Of 111 140

Vili

LIST OF FIGURES

Figure 1.1 Applications Of MOIE - - LH nọ TH HH Hệ 2Figure 2.1 The synthesis Of MOE - - - c 1n HH TH ng net 5Figure 2.2 Metal clusters in the synthesis of MOIES 75-5535 *+vEseeseeereree 6Figure 2.3 Organic linkers in the synthesis of MOIEs 6 + *+sskkseeseeeske 6Figure 2.4 Statistics on metal ions and organic linkers in MOF materials according to

Figure 2.5 The Zre6Q4(OH)4(-CO2)12 cluster is presented in stick-and-ball (a) and

polyhedron (b) The SBU shape is cuboctahedron (C) . 5+5 «<< ++seesseereess 8Figure 2.6 The crystal structure of UiO-66 via two different VIeWS «- 9Figure 2.7 The crystal structure Of ID T~52 + + xxx HH ng ri 9

Figure 2.8 The crystal structure of MOF-808 The tetrahedral and adamantane shaped

cages are shown by blue and pink spheres, resp€CtIV€Ìy - -«cc«cscsssseesrske 10

Figure 2.9 Various Brønsted Acid Sites in MOFS ccescceeseceseeceseeeeeeesseeeneeseaeees 13

Figure 2.10 'H-NMR of UiO-66-NH2 và UiO-66-RarSO3H materials 18 Figure 2.11 NĐ CP-MAS NMR of H2BDC-NH2? linker (a) and anilinium on UiO-66

1 18

Figure 2.12 ”P MAS NMR of TMPO on Zr-BTC (a), sulfated Zr-BTC (b), and

sulfated Zr-BTC on air by solid NMR measurement on Bruker Avance-500 MHz Theblack line represents the non-electrolyzed sample, the red line represents the peak, andthe green line represents the de-electrode peaked - - «+ ++ss+++se+xsersseeresexs 19Figure 2.13 The structure of Brønsted acid VNU-11-SO4 for the synthesis of

Đ€TIZOXZOÌ€ G0 HH TT 23Figure 2.14: Applications of 5-HMIE ĩc LH HH HH TH TH Hư 24

Figure 2.15 Describe some design directions and synthesis of MOF materials foradsorbent direction D0088 ằe 27

Figure 2.16 Structure of methylene blue (a) and methyl orange (b) 28

Figure 2.17 Structure of 1IỌG - - c6 1E 1183911 8393183911 91 1993 19 11 1 ng ng rrn 28

1X

Figure 4.1 a) PXRD patterns b) TGA curves, c) FTIR spectra and d) Na isotherms ofZr-BDC-ST and Zr-BDC-MW samples The filled and opened symbols represent theadsorption and desorption processes, T€SD€CfIV€ÏY - Q2 S1 net 41Figure 4.2 SEM images of Zr-BDC-ST (a) and Zr-BDC-MW (Đ) 42Figure 4.3 The conversion of 1 at 50 °C using 0.5 mol% Zr-BDC-MW in the pyridinePOISONING 11 e 45

Figure 4.4 PXRD patterns of Zr-BTC and Hf-BÌTC - - 555 + s+sserssereeres 48

Figure 4.5 FTIR spectra of Zr-BTC (a) and Hf-BTC (b) - 5+ ++s<++<+sss 49Figure 4.6 SEM images of Zr-BTC (a) and Hf-BTC (b) 5 +-c£++x+scxseess 49Figure 4.7 TGA curves of Zr-BTC (a) and Hf-BTC (b) -.-+<c<+<c<+ec++ 50

Figure 4.8 N2 isotherms of Zr-BTC (a) and Hf-BTC (b) (Solid and hollow circlesrepresent adsorption and desorption pOITI(S) cece - + 13k key 51Figure 4.9 Acid—base titration curve (blue) first derivative (red) of Zr-BTC (a) and

000000007 52Figure 4.10 a) PXRD patterns, b) TGA curves, c) FTIR and d) N2 isotherms of Hf-BTC (blue) and Hf-BTC-SOs (red) samples The filled and opened symbols representthe adsorption and desorption processes, rESDeCf{IV€ÏY - - Ăn re 57

Figure 4.11 The images of SEM (a, b), TEM (c, d), and EDS (e) of the activated

Figure 4.12 a) The effect of temperature and time reaction of fructose and b) glucose

conversion to 5-HMF Reaction condition: 1 mmol monosaccharides, 6 mmol[EMIM]CI and 30 mg Hf-BTC-SO4 0.0 ce eeceescesesseceecesecenesseeeaeceeeseeeaeeeaeceaeseneeaeenes 62

Figure 4.13 PXRD analysis of Hf-BTC-SOx after the glucose conversion and theyield of 5-HMF from the reuse of CafaÏySf - 0 5 ng nh nrưy 64

Figure 4.14 a) PXRD patterns b) TGA curves, c) FTIR and d) N2 isotherms of

Zr-NDC-ST and Zr-BDC-MW samples The filled and opened symbols represent the

adsorption and desorption processes, T€SD€CfIV€ÏY S1 re 66Figure 4.15 SEM image of the nano Zr-NDC-MW sample - «<< ce+ 67Figure 4.16 a) Effect of concentration and b) pH on MB and MO adsorption of Zr-NDC-MW —— 68

Figure 4.17 The experimental data for (a) Langmuir fitting model and (b) Freundlich.

Figure 4.18 a) Pseudo-first-order and b) pseudo-second-order kinetics models for adsorption of MB and MO on the Zr-NDC-MỀW HH HH, 71 Figure 4.19 a) Thermodynamics analysis for the dye adsorption by Zr-NDC-MW: The plot of In (qe/Ce) V8 L/ Ï 1 x1 91 931 31930111 HH Hư HH nh tư 72

Figure 4.20 a) Recyclability of Zr-NDC-MW for dye removal b) PXRD pattern of

Zr-NDC-MW before (blue) and after five cycles of dye removal (red) in comparison

to the simulated pattern (blaCK) - - G1 9E HH TH HH Hà 74 Figure 4.21 Proposed mechanism for adsorption process of MB and MO by Zr-NDC

TH II 74

Figure 4.22 PXRD patterns of Zr-BDC-SU (a) and Hf-BDC-SU (b) 75

Figure 4.23 FTIR spectra of Zr-BDC-SU (a) and Hf-BDC-SU (Đ) 76

Figure 4.24 TGA curves of Zr-BDC-ST (a) and Hf-BDC-ST (b) -«- 76

Figure 4.25 a) Na isotherm adsorption and b) the pore size distribution of Zr-BDC-SU and Hf-BDC-SU Solid and hollow circles represent adsorption and desorption points ba seeecaceccesseecesseecessecccsaseccessecceseeceessececsaseceesseeccesseccsaeeccesseccesseeecenssecesseecenseeesenseeeenseeeens 77 Figure 4.26 SEM images of the Zr-BDC-SU (a) and Hf-BDC-SU (Đ) 78

Figure 4.27 The effect of IND concentration (a) and adsorption time on Zr-BDC-SU (0) ee 79 Figure 4.28 Bright field and green Fluorescence field images of Zr-BDC-SU (a and e), Hf-BDC-SU (c and g), IND/Zr-BDC-SU (b and f), and IND/Hf-BDC-SU (d and h) (Scale bar: 200 JHIT)) - 7G G1113 12111 910119101 HH HH ng 79 Figure 4.29 PXRD of Zr-BDC-SU and Hf-BDC-SU after IND adsorption 82

Figure 4.30 Proposed mechanism for adsorption process of IND by Zr-BDC 83 Figure 4.31 Microscopy images in fluorescence mode of IND/Zr-BDC-SU and IND/Hf-BDC-SU after immersion in KF solution at concentrations from 0-1000 ppm (photo taken at 200 Um SCAÌÏ€) - 5 G0 1211123119112 11910 911111 HH ng rệt 83

Figure 4.32 Microscopy images in fluorescence mode of IND/Zr-BDC-SU and IND/Hf-BDC-SU after immersion at KF concentration of 1000 ppm from 30 min to

120 min (photo taken at 200 Um SCà) - 25 G5181 E3 EEEEEESEEsrserereerreee 84

xi

LIST OF TABLES

Table 2.1 Summary of some reported Zr-MOBFS .0 cecceesccceseeesneeeseeeeneeesaeeeseeeeneeeeaees 8

Table 2.2 Summary of some Brønsted acid MOF materials that catalyze 5-HMF fromfructose and ØÌÏUCOS€ - - 5 + TH TH TH HH HT TH TH HH Hư HT T nưệt 25Table 4.1 Properties of Zr-BDC-ST and Zr-BDC-MẮW Ăn SHenHheiey 42Table 4.2 Comparison of catalysts in the synthesis of 2,2-diphenyl-2,3-dihydroquinazolinone-4(1 HÏ)-OT€ <5 3113911131113 111911 9111 ng ng 44Table 4.3 The quinazolinone compounds from the anthranilamide and ketones oraldehydes reaction under the Zr-BDC MW catalyst - cc TS e, 47Table 4.4 Properties of Zr-BTC and Hf-BÏTC . - 6 xe ssessrserserek 50Table 4.5 Comparison of catalysts in the synthesis of 2,2-diphenyl-2,3-

dihydroquinazolinone-4(Ì H)-OT€ - <5 111911139101 19 11 911 9v 1g ng ng 53

Table 4.6 Comparison of microwave irradiation and solvent-free methods withprevious references in the synthesis of 2,3-dihydroquinazolin-4(1H)-one 54Table 4.7 Hammett indicator test F€SUÏ{S - 26 SG 31321111113 11811181 1 1 key 59Table 4.8 Optimization of solvent and catalytic loading in the synthesis of 5-HME 60Table 4.9 The comparison of catalysts for the conversion of monosaccharides 63Table 4.10 Properties Of Zr-NIDC - . + 111993119 11191 ng rưn 67Table 4.11 Adsorption capacities (qo) of MB and MO on Zr-NDC-MW and other

\ 1901117 69Table 4.12 The fitting results of Langmuir model and Freundlich model 70

Table 4.13 Thermodynamic study for the adsorption process of MB and MO on

Zr-NDC-MW at initial concentration of 100 mg LL'Ì 5: ¿5+5 5++t+t+t+t+xexsxexerexeress 73

Table 4.14 Properties of Zr-BDC-SU and Hf-BDC-SU 2-55 << <++c+ssx 78

Table 4.15 Adsorption capacities (qe) of IND on various Zr-MOEs 80Table 4.16 Adsorption models for IND onto Zr-BDC-SU 2555 5<<<++<+ 81

Table 4.17 Thermodynamic values of the IND adsorption onto Zr-BDC-SU with the

initial concentration of 1.5 Mg ML Ì 2-55 + S+E+E+E+E+EEEEEEeEexexexetevzererererexrre S1

xH

LIST OF SCHEMES

Scheme 2.1 The isomerization reaction of o-pinene OXide -««++ss<++ss+2 15

Scheme 2.2 The isomerization reaction Of O-PINENe eeeeeseeeteeeeeeeeeeesteeeeeeenees 15 Scheme 2.3 The isomerization Of 0-PIT€I - 5 + xxx ng ni 16 Scheme 2.4 The synthesis of UiO-66-RArSO3H from UiO-66-NH2 and

o-H0 2)/20196:101601910/3)500).8Arr,un4 17

Scheme 2.5 The synthesis of quinazolinone derivatives using Pd salt as catalysts .20

Scheme 2.6 The synthesis of quinazolinone derivatives using H3PO3 catalysts 20

Scheme 2.7 The synthesis of quinazolinone derivatives using iodine and metal-free CAtALYSts oo 6 e 20

Scheme 2.9 The synthesis of quinazolinone between o-aminobenzamide and methanol using iridium complex and cesium acetate catalysts 21

Scheme 2.10 The synthesis of 2-phenylquinazolin-4(3H)-one using Fe-MOE 21

Scheme 2.11 Synthesis of quinazolinone utilizing the sulfated MOF-808 catalyst 2 1 Scheme 2.12 The synthesis of benzoxazole derivatives using samarium triflate 22

Scheme 2.13 The synthesis of benzoxazole derivatives using p-toluenesulfonic acid A .- ” : 22

Scheme 2.14 The synthesis of 5-HMF from monosaccharides -. « ««- 25

Scheme 4.1 The reaction of anthranilamide and propan-2-one - « «+ 43

Scheme 4.2 The synthesis of 2,2-diphenyl-2,3-dihydroquinazolinone-4(1H)-one 44

Scheme 4.3 The proposed cyclization mechanism of anthranilamide and propan-2-Òii 8i 100108 46

Scheme 4.4 The cyclization reaction between anthranilamide and benzophenone 52

Scheme 4.5 Catalytic application of Hf-BTC for the preparation of quinazolinone Bsac0 TT 54

Scheme 4.6 Catalytic application of Hf-BTC for the preparation of 2-phenylbenzoxazole, 2-phenylbenzimidazole and 2-phenylbenzith1azole 55

Scheme 4.7 Proposed mechanism for the synthesis of 2-aryl benzoxazole, 2-aryl benzimidazole, and 2-aryl benzothiazole using Hf-BTC as catalyst 56

Scheme 4.8 The mechanism of glucose conversion into 5-HMF using Hf-BTC-SO¿ in "0019810001522 / 64

xiii

Brunauer-Emmett-Teller1-butyl-3methyl-imidazolinum chloride1,1'-Biphenyl-4,4'-dicarboxylate

Fourier transform infrared spectroscopy

Gas chromatography-mass spectroscopy

1,4-Bis(2-(4-carboxyphenyl)ethynyl)benzene5-Hydroxymethylfurfural

Hong Kong University of Science and TechnologyHigh resolution mass spectroscopy

Hard/soft acid/baseIsoreticular organometallic frameworkMaterials Institute Lavoisier

Methylene blueMicrowave

Methyl orange

Metal-organic framework1,4- Naphthalenedicarboxylate2,6-Naphthalenedicarboxylate

XIV

Porous Interpenetrated Zirconium OrganicFramework

Post-synthetic methodPhosphotungstic acidPowder X-ray diffractionSecondary building unitSingle crystal X-ray diffraction

Scanning electron microscopy

SolvothermalThermal gravimetric analysisUniversity of Oslo

Ultraviolet-visibleVietnam National University

Zeolitic imidazolate framework

XV

1 INTRODUCTION

Metal-organic frameworks (MOFs), crystalline porous materials consisting ofmetal clusters and organic bridges, have attracted much research attention in the past 20years [1] These materials have been received with widespread attention for several

fields, including gas storage and separation, catalysis, sensing, drug delivery, proton

conduction, and water treatment due to their long-range ordered structure, high specificsurface area, tunable composition, as well as almost infinite structural diversity (Figure1.1).

exemplary chemical syntheses where zeolites and related solids are limited [3, 4] Lewis

acid (LA) and Brønsted acid (BA) play an essential catalytic role in chemical

2

transformations [5] The homogeneous acid are also limited in terms of their lowreusability, corrosiveness, and pollution [6] Meanwhile, heterogeneous acid catalysts arehighly desirable alternatives to conventional homogeneous catalysts that suffer from theinherent limitations described above Solid supports such as organic polymers and porousmaterials have shown advantages such as high performance and ease of recovery [6] Theintroduction of defects can drastically increase the catalytic activity of defective MOFssince they have a significant impact on the porosity, mechanical properties, and Lewis orBrønsted acidities LA-MOFs have been exploited as heterogeneous catalysts forreactions such as cyclopropanation, Henry, Friedel-Crafts, cyanosilylation, cyclization,Friedlander, acetalization, hydroformylation, Businesselli, Claisenschmidt condensation,

Beckmann rearrangement, Sonogashira reaction, and polymerization BA-MOFs can

catalyze many organic reactions, such as the Diels-Alder reaction, acetalization,isomerization of pinene oxide and citronellal, and dehydration of carbohydrates [7] Thecoexisting with LA and BA sites in various Zr-MOFs can contribute as efficientheterogeneous catalysts for Friedel—Craft alkylation, cycloaddition, dehydration [8, 9].Recently, some MOFs have solid frameworks and high stability In solvents,encapsulating the guest molecule inside the pore as an adsorbent [10] The contribution ofBrønsted acidic sites in MOFs for ammonia capture, methylene blue, and indole wasobserved alongside Lewis acidic open metal sites [7, 11-15]

There are many approaches to introduce acid sites to MOFs, such as using themetal nodes or organic linker, as well as using MOFs as a host for additional catalyticsites like nanoparticles or enzymes Post-synthetic modification of the MOF backbone is

also possible, as well as using MOFs as a precursor for the formation of nanoparticles or

single-site catalysts through controlled decomposition These approaches can createdefective materials, which affect their acidic and pore space for catalytic and adsorptionapplications MOFs that have high porosity, thermal stability, and chemical stability areideal for introducing LA and BA sites without compromising the porous framework.Among carboxylate-based porous MOFs, CrqII), AI(HD, V(V), Fe(ID, and Zr(V)) tend

to show the highest values stability against water vapor Among that, Zr- or Hf- based

MOFs show higher thermal and chemical stability by the strong interaction between hard

Lewis acid (ZrV) or Hf(IV)) and hard Lewis base (O”) [16] Moreover, defective

structures are shown in the Zr-MOF backbone, which is lacked components such asorganic linkers, metal-containing secondary building units, or both, enhancing diffusionand offers exciting acidic properties [17] Synthesizing zirconium MOFs, includingmonocarboxylic acids as modulators, can tune the textural properties or promote theformation of structural defects The post-synthesis methods (PSM) process of sulfuricacid (H2SO4), phosphoric acid (H3PO4), and phosphotungstic acid (PTA) on Zr-MOF-

808, NU-1000, and MIL-101(Cr) introduced BA sites without collapsing the structure ofthe porous material framework [18] Therefore, Zr- and Hf-MOFs are suitable materialsfor detailed research for fabricating and applying acidic MOFs as catalysts andadsorbents

2 LITERATURE REVIEW

2.1 Introduction of MOFs

MOFs can be designed by consideration of preferred topologies between metal

clusters and organic linkers to satisfy each type of desired application '!*! Design

chemical structures, surface chemistries, and coordination space functionalization innovel ways through the appropriate selection of organic linkers, these clusters can belinked to each other, resulting in one- to three-dimensional highly-crystalline frameworks[20]

Figure 2.1 The synthesis of MOFs

Most metal clusters are metal complexes, including alkali and transition metalsused to synthesize MOFs (Figure 2.2) [19] Transition metals are commonly used because

of their strong affinity for organic heteroatoms such as oxygen, sulfur, and nitrogen inorganic linkers and their attractive properties for many applications Among the reportedMOF structures, the Zn(II)- and Cu(I)-based metal-organic frameworks (Zn-MOFs andCu-MOFs, respectively) have been early and widely studied [21, 22] However, theimportant drawback of these MOFs limiting their use in industry is their poor stability inmoisture and protonic solvents because of the lability of Zn(I)-carboxylate and Cu(II)-

carboxylate bonds To overcome this drawback, more chemically stable MOFs have beendeveloped.

Ma(CO¿)a

#ZnuO(COza)s MzO(COzIs (M = Cu, Zn, Fe, ZrgO.(OH)4- ZrOglGOa)s

(M=Zn, Cr, Mo, Cr, Co, and (COs)2 +

In, and Ga} Ru} 5

Figure 2.2 Metal clusters in the synthesis of MOFs.[19]

Linkers in MOF structures are usually organic compounds such as carboxyl,sulfonic, hydroxyl, or nitrogen, especially multi-carboxylic acids (Figure 2.3) Amongthem, carboxylate-containing compounds are usually used as linkers in MOFs due to theirability to bind many metals and lock them into rigid structures Besides, organic linkerscan be extended by adding one or more benzene rings to the linker structures to increasepore sizes and specific surface areas, which has enhanced the performance of our MOFs[19, 23-25]

S COOH COOH COOH N

Oxalic acid Fumaric acid Terephthalic acid Benzene-1,3,5-tricarboxylic acid 4,4-Bipyridine

COOH COOH OH

OH HO3S SO3H

COOH

HO HO OH a 7

COOH COOH SO3H HN—N

2,5-Dihydroxy- 2,5-Dimethylterephthalic acid 2,4,6-Trihydroxybenzene- 1H-pyrazole-4-carboxylic acid

terephthalic acid 1,3,5-trisulfonic acid

Figure 2.3 Organic linkers in the synthesis of MOFs [19]

Recently, there are some MOF materials with exceptional strength in water andsome outstanding organic solvents such as ZIFs (Zeolitic imidazolate frameworks), MILs(Materials Institute Lavoisier), M-MOF M=(Zr, Hf, Ce, V, and Ln), which are combinedaccording to the rule of Pearson’s hard/soft acid/base (HSAB) principle (Figure 2.4) [18].Zirconium or hafnium-based MOFs (Zr-MOF/Hf-MOF) possess exceptional thermal andchemical stabilities thanks to the high charge density of metal (Zr(IV) & Hf(IV)) and astrong affinity with carboxylate-based ligands, promising various applications Besidesthe highly porous characteristic, the active sites such as Lewis acid, Brgnsted acid, redox,

biomimetic enzyme, electric, and photochemical enabled MOFs to be used in separation

and catalysis [26]

Hard Lewis Base Soft Lewis Base

Carboxylates Azolates

Co?*, Niz*, Cutt, 2n?* AM Cr+ Fe Tịtt zr Co*, Ni, Cutt, Zn? AR Crt, Fett, Tit, Zr4

Representative MOFs 1 1 Representative MOFs

MIL-100 (Al, Fe, Cr) ZIF-7, 8, 11 (Zn) MIL-125(Ti), UiO-66 (2r) Cu,(BTP}, Ni;(BTP), Co(BDP)

Figure 2.4 Statistics on metal ions and organic linkers in MOF materials according to

HSAB theory [18].

The most common cluster in Zr-MOFs is Zr6Ox(OH),(-CO2); cluster, which Zr**

cation is capped by oxo and hydroxyl groups on the triangular faces of the octahedron

(called Ha-O and u3-OH, respectively) and connected with the carboxylate groups on the

octahedron edges (Figure 2.5) The Zr clusters can combine with organic linkers by the

diverse arrangements from 4 to 12 coordination to create these MOFs that have large porediameters and specific surface areas (Table 2.1)

Figure 2.5 The ZreO4(OH)4(-CO2)12 cluster is presented in stick-and-ball (a) and

polyhedron (b) The SBU shape is cuboctahedron (c) [28]

Table 2.1 Summary of some reported Zr-MOFs

Zr-MOFs Zr core Number of SBET Ref.

UiO-66 is a remarkable three-dimensional porous material that is composed of

12-links clusters and structural units Its crystal has a face-centered-cubic structure with

fm-3m symmetry and a lattice parameter of 20.7 A This MOF exhibits high hydrothermal

and chemical stability, and its crystal structure remains intact below 500°C Additionally,UiO-66 can withstand mechanical pressures of 1.0 MPa and remain structurally stable insolvents like water, dimethylformamide (DMF), benzene, and acetone It also has strong

acid resistance and some alkali resistance The aperture in UiO-66 consists of around ~11

A octahedral cage and a 8 A tetrahedral cage connected by a 6 A triangular window

8

(Figure 2.6) The specific surface area of UiO-66 is typically between 600 and 1600 mŸ gˆ

! and it can be controlled by factors such as crystallization time and temperature or

adding modulators with various functions The degree of ligand defects in the UiO-66structure directly affects its specific surface area [32, 33]

Figure 2.6 The crystal structure of UiO-66 via two different views

Zhong and co-workers successfully synthesized MOFs with SBUs ofoxohydroxozirconium(IV), [ZreO4(OH)4] clusters and NDC _ linkers through asolvothermal method in DMF with the presence of HCl [34] In the same year, Kaskeland coworkers were synthesized the same Zr-NDC MOF (namely DUT-52 (Zr)) bysolvothermal method, but with a slight modification by using acetic acid with differentconcentrations as a structural modulator

|

Figure 2.7 The crystal structure of DUT-52

A systematic absence analysis indicated the crystal structure is a face-centered

cubic space group Fm-3m (a = 23.910(3) A), consisting of interconnected ZreO4(OH)4

SBUs A network of fcu topologies contained octahedral and tetrahedral micropores with

9

diameters of 9.3 and 7.5 A (Figure 2.7) The octahedral pore and its relationship with the tetrahedral cages and triangular windows that are 4.35 A in diameter [35] DUT-52 is

isoreticular to UiO-66 which the Sper of this MOF was found to be greater than that ofUIO-66, making it a promising candidate for various applications [28]

Figure 2.8 The crystal structure of MOF-808 The tetrahedral and adamantane shaped

cages are shown by blue and pink spheres, respectively

Moreover, these MOFs consist of Zrs-octahedra capped with by p3-O and y3-OH

groups which have the stronger Brgnsted acid than 12-coordinated MOF [7, 36, 37] Inthe Zre clusters with lower coordination numbers, the carboxylate linkers are replaced bymonocarboxylate compounds, which play an important role in nucleation and crystalgrowth of Zr-MOFs synthesis [7, 36-38] In case, Zr-BTC is a structure defect MOF,constructed from Zrs(H:-O)4(Ha-OH)4(HCOO)s clusters and tricarboxylic acid (H3BTC)linkers (Figure 2.8), which have OH groups and formic acid on Hf cluster to play anactive sites for catalysis [27, 38-41]

2.2 Acidic of MOFs

Lewis acid sites and Brgnsted acid sites characterize solid acid catalysts The acidic

properties of solid acids are considered in terms of their acid sites, Brønsted or Lewis

nature, the concentration of available acid sites, and the strength and accessibility of acidsites Its thermal stability, regenerative ability, and overall longevity are important for itsapplications

10

A Lewis acid is a substance that accepts an electron pair.

A- is the conjugate base of acid HA, and BH' is the conjugate acid of base B

Early Lewis acid catalysts were usually based on the leading group or earlytransition metal halides However, these Lewis acidic metal salts have poor solubility innonpolar organic solvents, are sensitive to moisture, and have short lifetimes duringcatalysis Researchers have made great efforts in the past decades to overcome these

shortcomings to develop heterogeneous Lewis’s acids catalysts such as zeolites, metal

oxides, and resins Solid acid catalysts can be easily separated from the reaction mixturefor reuse and are compatible with flow catalysts but have moderate Lewis’s acidity, lowactive site density, and heterogeneous active sites Metal clusters in MOF have affordedoutstanding single-site solid catalysts with unique electronic properties and stericenvironments that are not accessible via conventional homogeneous chemistry or

heterogenization approaches Due to large amounts of unsaturated metal centers (UMCs),

MOFs can act as Lewis acid catalysts [42] The first use of MOFs as Lewis acid catalystswas reported in 1994 by Fujita et al They synthesized a Cd-bipyridine MOF and studied

its ability to clathrate with o-dibromobenzene and its cyanosilylation reaction of

benzaldehyde with cyanotrimethylsilane Since then, various MOF reactions have beenextensively attempted, including cyanosilylation, ring-opening reaction, Mukaiyamaaldol reaction, Knoevenagel condensation, redox reaction, and CO2 fixation Apart from

lãi

Lewis acidity, Brønsted acidity in some MOFs greatly expands their catalyticapplications.

2.2.1 Synthetic strategies

Acidic sites originate from removing terminally coordinated solvent molecules onthe metal sites or coordinative defects because of missing linkers or clusters Besides,post-synthetic methods incorporating or attaching moieties with Lewis or Brønstedacidity also help introduce acid sites into MOFs Defects lead to nonstoichiometric metal-to-linker ratios Missing linkers are often seen being compensated by formates, oxygen,hydroxyl groups, water, and chloride Defect engineering is an effective way to createacid sites inside Zr-MOFs, wherein the defect concentrations and compensating groupscan be systematically tuned In the recent literature, two synthetic routes have been used

to prepare MOFs with different defects, including (i) de novo synthesis and (ii)

post-synthesis processing methods [20] Beside the possibility to reduce the ZreOa(OH)x !?*

SBU connectivity in Zr-MOFs synthesis, monocarboxylic acids such as formic acid (FA),acetic acid (AcOH), and benzoic acid (BzOH) can control the crystallization rate byinfluencing equilibrium reactions (framework formation) Still, at high concentrations,this leads to the formation of defects [20] In 2016, Shearer et al investigated the effects

of different modulators such as FA, AcOH, TFA (trifluoroacetic acid), and DFA(difluoroacetic acid) on the defect chemistry and Brønsted acidity on UiO-66 In addition,Vermoortele et al used strong acids such as perchloric acid (HCIO¿) and trifluoroaceticacid (TFA) in the post-synthetic modification of MIL-100(Fe) to form additionalBrønsted acid site near the Lewis acid site [43]

BA MOF can be synthesized in several ways, such as 1) encapsulated Brønstedacid molecules by post-synthetic modification on pores, 11) ligated Brønsted acid groups

on metal cluster, or 11) covalently bound BA functional groups of organic linkers (Figure2.9) H2SO4, HaPOx, o-sulfobenzoic acid anhydride, and 1,3-propanesultone were diffusedinto the structural pores of some types of MOFs such as MIL-101(Cs), HKUST-1, MIL-

12

100, UiO-66, UiO-66-NH2, and IRMOF-3 [8, 44, 45] For instance, Vermoortele et al.used strong acids such as HClO and TFA for the post-synthetic modification of MIL-100(Fe) [43] The authors observe the formation of additional Brønsted acid sites in closevicinity to the Lewis acidic sites, which was proven by CO chemisorption experiments[20] However, this approach has some problems, such as i) poor stability of MOFmaterials, 11) low encapsulation efficiency, and iii) limited pore size of MOF thanBrønsted acid molecules [7] To introduce large molecules and minimize the loss of BA,the alkaline form of BA was added simultaneously during the synthesis of MOFs [7].

3 Covalanity

Birensled acid ¬

of organic = |

›

Figure 2.9 Various Brønsted Acid Sites in MOFs [7]

The hydroxyl, alcohol, oxalic acid, and sulfuric acid interact with a metal cluster

in MIL-53(Ga) [Ga(t2-OH)(BDC) (BDC = benzene dicarboxylate)], and MOF-69C[Zm(u2-OH)2(BDC)] showed the BA properties The BA active sites by hydroxyl group

in many M-MOFs (M= AI, Cr, Cu, Fe, In, Ni, Sc, Zn, and Zr) [7, 46, 47] Shearer et al.systematically studied the impact of different modulators such as FA, AA, TFA, andDFA on the defect chemistry of UIO-66 [48] and a correlation between the defectconcentration and the Brgnsted acidity of the modulator [20] Moreover, the bound watergroup in the metal cluster can act as Brønsted acid because this hydrogen is moreBrønsted acid than unbound water molecules The Brgnsted acid sites, in the case ofwater bound to the metal, need suitable activation conditions to activate the HOH?’ sites.The same is true for some polar protons, such as methanol, trifluoroethanol, and

13

hexafluoropropan-2-ol Some of the limitations that can be stated in this class of materialsare the dissociation of Brønsted acid, too many hydroxyl or alcohol groups in thestructure which can lead to hydrogen bonding with active protons acid, and the difficulty

in determining the conversion between Brønsted acid, Lewis acid, and Lewis base [7]

After the modulator influences MOF kinetics and crystallinity, it is intuitive thatrapid crystallization processes lead to the formation of point defects and missing linkers

or missing cluster defects There are various methods for synthesizing MOFs, includingsolvothermal (ST), sonochemical, ionothermal, microwave (MW), and mechanochemicalprocesses However, microwave-assisted synthesis has proven to be quite effective in thefield One of the main advantages of this technique is the short reaction time, which

allows for faster nucleation rates and modified MOF properties MW heating affects the

pore size and the morphology of MOFs MW-assisted synthesis of MOF-74 (Ni) showedthat the CO; removal capacity of MOF increased as the activation temperature increasedfrom 150 °C to 250 °C The particle size of MIL-53 (Al) became narrow under themodulation of the power of microwave [49]

2.2.2 Characterization techniques

The classification of the acid sites (Brønsted acid, Lewis acid, or mixture), acidstrength, and acid concentration are some of the essential factors for determining theacidic properties of solid acidic materials Some of the methods of surface acidityanalysis that can be used are indicators, titration methods, specificity tests, gas adsorptiontechniques, physical methods (oscillometer, spectroscopy, etc.), solid nuclear magneticresonance, and single crystal X-ray diffraction)

2.2.2.1 Hammet indicators and titration methods

The donor properties of solid acids and solid superacids are based on their ability

to donate protons in some indicator solutions of the Hammett indicator series Thestrength of a solid acid is evaluated based on the color absorption of the indicator solution

on that solid The color adsorbed on the surface of the solid acid in the acid form of the

14

indicator indicates that Ho will be less than the pKa of the indicator In the Hammettscale, concentrated H2SOz solution has an index of Ho = -12, and superacids have astronger acidity than concentrated HaSÖa, ie, Ho < -12 [50].

catalyst-campholenic aldehyde in the case of a Lewis acid, and the resulting product is a mixture

of alcohol compounds such as trans-carveol, trans-sobrerol, and p-cymene under thepresence of Brgnsted acid Another reaction that can be used to determine the acidity of amaterial 1s the isomerization of a-pinene (Scheme 2.2) [7, 50]

Scheme 2.1 The isomerization reaction of a-pinene oxide.[7]

ng " B.A or L.A (+)- Sago (+)-Neo- Ceopulego )-Iso-isopulegol (+)-Neoiso-isopulegol

CHO O 0.

| OH ‘OH

( lsopulegol (-)-Neo-isopulegol (-)-lso-isopulegol (-)-Neoiso- <ovisoputege

Scheme 2.2 The isomerization reaction of o-pinene.[7]

15

In addition, the o-pinene isomerization reaction can be used to examine the

strength of the Brønsted acid sites (Scheme 2.3) Under the action of a strong Brønstedacid catalyst, a mixture of diene products such as limonene, y-terpinene, a-terpinene,terpindene va p-cymene Meanwhile, using materials with Brønsted acid properties will

be aided in the production of alkene mixtures such as camphene, a-fenchene, tricyclene

Scheme 2.3 The isomerization of ơ-pinene [7]

2.2.2.3 Gas sorption techniques

The adsorption of volatile amines such as NHs, pyridine, and n-butylamine can beused to determine the number of acid sites on solid acid materials The analyticalprocedure of this method is based on the chemical interaction between the acid and basesites Acid strength is related to the heat of adsorption or heat required for desorption and

is analyzed by calorimetry or thermal programmed desorption (TPD) However, thismethod has not been widely used because of some limitations on the strength of MOFmaterials in the base medium, the lack of knowledge to determine the actual internalcomposition of the pores, and the thermal stability of the MOF materials materials whenusing the TPD method [7].

2.2.2.4 Physical analysis

«* Infrared (IR) spectroscopy

16

Infrared spectroscopy has been successfully used to analyze the presence of acidcomponents in the Brønsted acid MOF structures The bonding vibrations of sulfone and

hydroxyl groups have been shown in UiO-66 and MOF-808 superacid materials,

respectively [50, 52] In Hakam et al., the peak of 1450-1650 cm! showed the bonding

between Brønsted acid sites in Cr-MIL-101 with pyridine [53] Vibration studies on the

CO range with bipyridine, phosphonate, and sulfonate can also be used to analyze thepresence of acid sites [7]

** Solid-State Nuclear Magnetic Resonance (NMR) Methods

NMR spectroscopy is a powerful spectroscopic method widely used in manyscientific and technical disciplines to determine the structure of compounds and mixtures

in quantitative analysis Proton oscillations in the material structure can be observed onNMR spectra and analyzed to demonstrate the presence of Brønsted acid sites [47] Forexample, in the synthesis of Brønsted acid MOF UIO-66-RArSOaH from the startingmaterial UiO-66-NH2 through modification with the o-sulfobenzoic acid anhydride group

(Scheme 2.4), 'H-NMR analysis is used to observe the formation of amide bonds

between the NH2 group and the anhydride group and the presence of the o-sulfobenzoicacid group (Figure 2.10 - 2.12) NMR analysis results show an oscillating N signal in theH:BDC-NH; bridge at position 59.7 ppm (Figure 2.10) and the presence of twovibrational signals of N in the material (Figure 2.11) The authors determined thematerial’s structure to exist in the amine form at 56.7 ppm and the anilinium form at137.2 ppm (Figure 2.12)

Figure 2.10 'H-NMR of UiO-66-NH2 và UiO-66-RarSO3H materials [54].

T

100 50 0

Figure 2.12 ”P MAS NMR of TMPO on Zr-BTC (a), sulfated Zr-BTC (b), and sulfated

Zr-BTC on air by solid NMR measurement on Bruker Avance-500 MHz The black linerepresents the non-electrolyzed sample, the red line represents the peak, and the green

line represents the de-electrode peaked [50].

2.3 MOFs for catalysis application

2.3.1 Synthesis of quinazolinone

Quinazolinones and their derivatives are an important class of nitrogen-containing

heterocycles due to their biological and pharmaceutical activities [1-4] These compoundsare valuable precursors for synthesizing various commercial drugs [5] However, thereare several synthetic protocols for 2,2-disubstituted-2,3-dihydroquinazolin-4(1H)-onederivative in the literature This synthesis was performed using Brønsted or Lewis acids,such as silica sulfuric acid, p-toluenesulfonic acid (PTSA), KAI(SOq)2.12H2O, Zn(PFO)),,Al(H2PO4)3, thiamine hydrochloride (VB1) ionic liquids, zeolites, resin, and aluminumsalts [56-62] These catalytic procedures have several drawbacks, such as large amounts

of catalyst, difficulty in catalyst recycling, toxic and corrosive reactants, and many waste

19

organic solvents and additives [57-59, 61, 62] Therefore, the exploration of efficient andenvironmentally benign catalytic systems for synthesizing 2,2-disubstituted 2,3-dihydroquinazolin-4(1H)-ones are in great demand.

In 2014, Jiang and coworker performed the reaction from 2-aminobenzamide andaryl halide with a palladium catalyst to synthesize quinazolinone [63]

Scheme 2.5 The synthesis of quinazolinone derivatives using Pd salt as catalysts

In 2015, Li and coworker synthesized quinazolinone derivatives from B-ketoesterwith o-aminobenzamide in the presence of phosphorous acid and ethanol [64]

o

ANH2 o 9 cat H3PO, NTM }Rạ

+ pte.

3 4 ° Y,

YH EtOH, 50 °C

NH; Ry= Me, Et Y=NH, S

Scheme 2.6 The synthesis of quinazolinone derivatives using H3PQ3 catalysts [65]

In 2015, Mohammed et al used 2-aminobenzamide with aryl methyl ketone in thepresence of an iodine catalyst [66]

° 10 mol % I o

Cau R hk DMSO, 110 °C, Oz - @(

NH, Arg HCHO care

Metal-free Ar,= Ph, pyrazole

Ara= Ph, pyrazole, biphenyl

Scheme 2.7 The synthesis of quinazolinone derivatives using iodine and metal-free

catalysts [66]

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In 2016, Li et al synthesized a quinazolinone derivative from the combination of

o-aminobenzamide with methanol in the presence of the catalyst [Cp*Ir(2,2'-bpyO)(H20)]

Scheme 2.8 The synthesis of quinazolinone between o-aminobenzamide and methanol

using iridium complex and cesium acetate catalysts [65]

Some MOFs were found to be an active catalyst for the synthesis of quinazolinone

To et al has reported the one-pot synthesis of quinazolinones via two steps under

Fe-MOF (namely VNU-21) as a recyclable heterogeneous catalyst (Scheme 2.10) Iron in

VNU-21 involved the oxidative CspỶ-H bond activation to achieve decarboxylation of

phenylacetic acids, and succeeding metal-free oxidative cyclization with aminobenzamides (Scheme 2.11) [67] In 2018, Phan et al synthesized quinazolinonesfrom Ø-ketoesters and benzamides in glycerol as a green solvent in the presence of

2-sulfated MOF-808 (Scheme 2.11) [68] However, these reactions also use some solvents

such as DMSO, DMF, or glycerol and there are no studies using ketones as reagents

2.3.2 Synthesis of benzoxazole

Benzoxazole is a heterocyclic compound with the molecular formula C7HsNO andoccurs in nature Several bioactive benzoxazole compounds are used as melatoninreceptor agonists, amyloid genesis, Rho-kinase inhibitors, and antineoplastic agents Inaddition, some benzoxazole derivatives manufacture pesticides, dyes, and luminescentagents in fluorescent detectors such as anion or metal cation sensors, textile additives,and plastics Benzoxazole and derivatives are synthesized from o-aminophenol orbenzoxazole with aldehyde, carboxylic acid, aryl halide, gem-dichloroalkene, nitrile,bisaryloxime, o-haloanilide, o-hydroxy-N-aryl-N,N-diakylformamidine, etc by heatingcirculation method under homogeneous catalysis (CuClz, CuBr›, Pt, Cu(OTf)2, metalcomplexes (Pt, Ru, Pd, Iz, NaClO), ionic liquid, and solid catalyst (nano Cu, amberlyst-15) Some synthesis methods are listed below:

In 2013, Gorepatil et al synthesized benzoxazole from o-amino(thio)phenols andaldehydes using samarium triflate as a reusable acid catalyst under mild reactionconditions in an aqueous medium [70]

ow 3 R 0.1 eq Sm(OTf)s - xa

YH H EtOH / HạO (2:1) Ỳ

55°C,2-6h

Y:S,O R: Ar, alkyl

Scheme 2.11 The synthesis of benzoxazole derivatives using samarium triflate[70]

In 2014, Mayo et al reported the cyclization reactions of 2-aminophenols with

ÿ-diketones catalyzed by a combination of Brønsted acid and Cul give various 2-substituted

Accordingly, a greener and more efficient catalyst for the synthesis of benzoxazole

is needed In 2014, Yang et al reported a recyclable mesoporous poly(melamineformaldehyde) catalyst as a green, heterogeneous organocatalyst for the synthesis ofbenzoxazoles in the presence of toluene as the solvent [72] Panahi and co-workersdeveloped a greener ruthenium-catalyzed synthesis of benzoxazoles using acceptor lessdehydrogenative coupling reaction of primary alcohols with 2-aminophenol underheterogeneous conditions [73] Recently, Maleki et al reported a green and efficientAg@TiO2 nanocomposite for the efficient synthesis of benzoxazole derivatives via one-pot condensation of 2-aminophenol and several aromatic aldehydes [74] In 2017, Doan

et al used the superacid Hf-BTC-SO4 (VNU-11-SO4, VNU = Vietnam nationalUniveristy) to synthesize benzoxazole from 2-aminophenol and aldehyde derivatives.Under the support of a strong Brønsted acid sites, the efficiency of the reaction wassignificantly increased than the conditions of only the Lewis acid sites and weak acidBrønsted sites of VNU-11 pristine [52]

benzoxazole [52]

2.3.3 Synthesis of 5-HMF

Biomass conversion of plant compounds is considered a new direction to limit theincrease of CO; from fossil energy production Converting cellulose into valuablesubstrate compounds such as 5-HMF, and levulinic acid is an interesting researchdirection [75] 5-HMF is a furan compound containing an aldehyde group and an alcohol

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at positions 2, and 5 This compound is important in producing renewable fuels andchemicals to produce the biofuel dimethylfuran and other molecules, as well as levulinicacid, 2,5-furandicarboxylic acid (FDA), 2,5-diformylfuran It is also very useful foressential molecules such as dihydroxymethylfuran and 5-hydroxy-4-keto-2-pentenoicacid [76].

cellulose under the catalyst of Bronsted acid and Lewis acid catalysts such as H2SOa,

HCl, AlCls, and CrC1: (Scheme 2.17) [77, 78] When producing HMF from glucose, atandem reaction is necessary This two-step process can be achieved using bi-functionalcatalysts for both the isomerization and dehydration reactions MOFs have been found to

be effective Lewis acid-type catalysts for the isomerization reaction, while Brønsted-acidcatalysts are used for the dehydration of fructose to HMF This approach could be apromising method for HMF production, and finding the right catalysts is key to itssuccess [79] MIL-101(Cr) material with free phosphotungstic acid group exists in MIL-

101 pore structure for the reaction to convert alcohol to styrene oxide [80], ordehydration to produce 5-hydroxymethylfurfural from glucose or fructose metabolism[81] Recently, PTA/MIL-101[81], NUS-6(Hf) [82], MIL-101(Cr)-SO3H [83] are

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