HOF is the omitted word of "Hydrogen-bonded Organic Framework". Probably you don't know this material, but it has very interesting features which might be a mainstream in the porous material's field.

1. 1Kazuya Tomita
Kyushu university

2. Porous materials
Porous materials have many pores in the structure
and the property relavant to it.
 Zeolite
A kind of aluminosilicates with robust structure
 MOF（Metal-Organic Framework）
Framework from metals and organic linkers
 COF（Covalent-organic Framework）
Framework which consists of covalent bonds 2

3. HOF (Hydrogen-bonded Organic Framework)
The organic framework from hydrogen bonds
Self-assembly
linkers HOF
Easy synthesis because of
being able to utilize hydrogen bonds
Easy reuse by recrystallization 3

4. However, if a novel HOF with superior properties is developed,
the mainstream in porous materials field might focus on HOF.
A new HOF, HOF5, was reported and it has
the best adsorption property of all HOFs
and it is even comparable to MOFs.
Delay of the reserch and inferior properties
to MOF by being fragile
due to hydrogen bond’s weakness
About HOF
 HOF’s defects
 New linker
4
HOF
Hydrogen bond points
L

5.  Synthesis of linker
HOF’s synthesis and the crystalline structure
HOF5 HOF5-a
 Changing the number of
hydrogen bond from
20 to 24 per one linker
 Volume shrinking by 21 %
 Tetraphenylethelene skeltone
 Formation of HOF5
from two types of units
 The structural change by
Desolvation From HOF5
to HOF5-a
5
L
If change occurs,

6.  N₂ adsorption isotherm is
Stepwise because of the transition
 HOF-5a’s BET surface area
is 1100 m²/g
Reversible structural change
 N2 adsorption isotherm (77 K)
HOF-5
HOF-5a
HOF-5
HOF-5a
HOF-5
HOF-5a
HOF5-a changes HOR5 by being soaked in
acetone in low temparature and
by eliminating solvents within pores
it changes HOR5-a.
The structure changes reversibly
6
 Powder XRD measurement
HOF-5a
HOF-5

7. selectivity｜CO₂/N₂(10:90)
Why does the HOF adsorb such lots of CO2?
Adsorption property and selectivity
 Adsorption isotherm (296 K)
 Adsorption selectivity (296 K)
N2
CH4
CO2
C2H2
7
C2H2 : Maximum value of
all reported HOFs
CO2 : comparable to
the best MOF

8.  The interaction between CO2
and HOF is mainly van der
Waals force, not hydrogen bond.
 Molecular interaction among
CO2 molecules which are guest
By Rietveld refinement,
details of sites was
elucidated.
 Two types of sites
Exploration of CO2 adsorption sites
 Neutron diffraction measurement
SiteⅠ SiteⅡ
8

9. CO2 adsorption in HOF5-a
 Interaction among CO2 molecules
 Quasi-one-dimensional adsorption
 The interaction is van der Waals
The result of DFT calculation is consistent with Rietveld refinement
Two types of adsorption energy
SiteⅠ 39.9 kJ/mol
SiteⅡ 37.3 kJ/mol
9
Exploration of CO2 adsorption sites

10. summary
 HOF5-a has high CO2 adsorption
capability and selectivity
 The interaction between CO2 and
HOF is van der Waals force
 Transition from HOF-5 to HOF5-a
by desolvation
 CO₂ molecules’
quasi-one-dimensional adsorption
10

11. 11
Supporting Information

12. 12
Crystalline datas

13. 13
Crystalline datas

14. 14
Structure
HOF5 HOF5-a

15. 15
Gas adsorption property
N2
CH4
CO2
C2H2
N2
CH4
CO2
C2H2
273 K
296 K

16. 16
Gas adsorption selectivity
296 K

17. 17
Comparisons with others porous materials

18. 18
HOF5 HOF5-a
Appearances of HOF5 and HOF5-a

19. 19
Calculation of BET surface area