This document discusses covalent organic frameworks (COFs), which are porous organic materials constructed through strong covalent bonds between organic building units. It describes various types of bonds and introduces COFs and metal-organic frameworks. The key advantages of COFs are their covalent linkages, porosity, crystallinity, and tunable properties. Common synthesis methods for COFs include solvothermal synthesis using solvents and heat and microwave synthesis for faster reactions. Characterization techniques and examples of 2D and 3D COFs are provided. Finally, potential applications of COFs in gas storage, catalysis, semiconduction and photoconduction are outlined.

1. Muhammad Ehsan
(2013652616)
Date: 2013-12-05
Bionano Chemistry Lab

2. Types of Bonding
Ionic Bonds
Covalent Bonds
Coordinate Bonds
Dipole Interactions
Van der Walls forces
Pi-Pi Stacking

3. Introduction

4. Covalent Organic Frameworks (COFs)
Covalent organic frameworks (COFs) represent an exciting new type of porous organic
materials, which are ingeniously constructed with organic building units via strong covalent
bonds.
Metal-Organic Frameworks (MOFs) are compounds consisting of metal ions or cluster
coordinated to often rigid organic molecules to form one-, two-, or three-dimensional
structures that can be porous.

5. Why to Synthesize COFs
Driving Force for the Synthesis of COFs:
Bringing
i) Covalent linkage
ii) Porosity and
iii) Crystallinity
within the same material
COFs posses
i) Low density
ii) Large surface area
iii) Tuneable pore size
iv) Facilely tailored functionality
v) Versatile covalent combination

6. Basic Concern
Covalent Bond Formation

7. Building Units

8. Classification of COFs
Depending on the building block dimensions, COFs can be categorized into
two-dimensional (2D)
three-dimensional (3D) COFs.
In 2D COFs, the covalently bound framework
is restricted to 2D sheets.

9. three-dimensional (3D) COFs.
In contrast, 3D COFs, which extend this framework three dimensionally
through a building block containing an sp3 carbon or silane atom,
characteristically possess high specific surface areas

10. Design and synthesis
Structure of building blocks
To obtain a crystalline and ordered COF, the structure of the building blocks
must meet two requirements:
 the formation reaction of the COF should be a reversible reaction.
Contain reactive groups,
monomers, oligomers, and polymers
 the geometry of the building blocks should be well preserved in the COF.
building blocks should be conformationally rigid,
and the bond formation direction must be discrete.

11. Synthetic Methods
Solvothermal synthesis
Microwave synthesis

12. Solvothermal synthesis
Monomers and mixed solvents
are placed in a Pyrex tube
Degassed via several
freeze–pump–thaw cycles
The tube is then sealed
and heated to a designated
temperature for a certain reaction
time.
The precipitate is collected,
washed with suitable solvents,
dried under vacuum to
yield the COF as solid powder.

13. Factors Affecting the Solvothermal Synthesis
Solvent combinations and ratios are important factors in balancing between framework
formation and crystallization when synthesizing highly crystalline COFs.
A suitable temperature is important to ensure the reversibility of the reaction. (85–120 0C)

14. Microwave Synthesis
Microwave synthesis provided several advantages over solvothermal
methods.
Produces COFs rapidly. Thus, large-scale synthesis is possible.
A sealed vessel is not required for the microwave synthesis.

15. Other Synthetic Methods
 Synthesis of monolayers on metal surfaces.
 Synthesis of monolayers on a (highly ordered pyrolytic graphite)
HOPG surface
 Synthesis of oriented thin films on graphene surfaces.
 Ionothermal synthesis
 Room-temperature synthesis

16. Structural Studies of COFs
 XRD, crystalline structure
 Infrared spectroscopy
 Solid-state NMR spectroscopy
 Elemental analysis
 X-ray photoelectron spectroscopy
are all useful for evaluating the linkages, terminal
groups, and compositions of the COFs.

17. Some Examples of COFs
Figure .(a) Schematic representation of T-COF 1 (left) and T-COF-3 based on thiophene based
building blocks, reproduced with permission from, copyright 2013 by the National Academy of Sciences of
the United States of America

18. Some Examples of COFs
Figure (a) Co-condensation of a truncated linker and a tetraboronic acid results in the functionalized 3D COF-102,
reproduced with permission from, copyright 2012 by John Wiley Sons, Inc.,

19. Some Examples of COFs
Fig. Co-condensation of monomers 11 and 21 to synthesize 2D HHTP-DPB COF and the proposed crystalline structure.
(Adapted with permission from Copyright 2011 American Chemical Society.)

20. Applications of COFs
The function of a COF arises from its porosity and molecular
skeletons
1.
•
•
•
•
Gas adsorption and storage
Hydrogen
Methane
Carbon dioxide
Ammonia
2.
Heterogeneous catalysis
3.
Semiconduction
4.
Photoconduction

21. To be continue…….