Record Complexity in the Polycatenation of Three Porous Hydrogen-Bonded Organic Frameworks with Stepwise Adsorption Behaviors

Article abstract of DOI:10.1021/jacs.0c02406

Hydrogen-bonded organic frameworks (HOFs) show great potential in many applications, but few structure-property correlations have been explored in this field. In this work, we report that self-assembly of a rigid and planar ligand gives rise to flat hexagonal honeycomb motifs which are extended into undulated two-dimensional (2D) layers and finally generate three polycatenated HOFs with record complexity. This kind of undulation is absent in the 2D layers built from a very similar but nonplanar ligand, indicating that a slight torsion of ligand produces overwhelming structural change. This change delivers materials with unique stepwise adsorption behaviors under a certain pressure originating from the movement between mutually interwoven hexagonal networks. Meanwhile, high chemical stability, phase transformation, and preferential adsorption of aromatic compounds were observed in these HOFs. The results presented in this work would help us to understand the self-assembly behaviors of HOFs and shed light on the rational design of HOF materials for practical applications.

Full text of DOI:10.1021/jacs.0c02406

Subscriber access provided by DALHOUSIE UNIV
Article
Record Complexity in the Polycatenation of Three Porous Hydrogen-
bonded Organic Frameworks with Stepwise Adsorption Behaviors
Yu-Lin Li, Eugeny V. Alexandrov, Qi Yin, Lan Li, Zhi-Bin
Fang, Wenbing Yuan, Davide M. Proserpio, and Tian-Fu Liu
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.0c02406 • Publication Date (Web): 26 Mar 2020
Downloaded from pubs.acs.org on March 26, 2020
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 8
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Record Complexity in the Polycatenation of Three Porous Hydrogen-
bonded Organic Frameworks with Stepwise Adsorption Behaviors
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
†
‼ ,∥
†
†,‡
†
§,*
Yu-Lin Li, Eugeny V. Alexandrov,
Qi Yin, Lan Li, Zhi-Bin Fang, Wenbing Yuan, Davide M.
Proserpio⊥,‼ ,*and Tian-Fu Liu†,‡,*
†
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences,
Fuzhou 350002, P. R. China.
‼
Samara Center for Theoretical Material Science (SCTMS), Samara State Technical University, Molodogvardeyskaya St. 244, Samara
4
∥
43100, Russia
Samara Branch of Р.N. Lebedev Physical Institute of the Russian Academy of Sciences, Novo-Sadovaya St. 221, Samara 443011,
Russia
‡
University of the Chinese Academy of Sciences, Beijing, 100049, China.
§
School of Environmental and Chemical Engineering, Foshan University, Foshan, 528000, China.
⊥
Dipartimento di Chimica, Università degli studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
KEYWORDS: Hydrogen-bonded Organic Frameworks, Polycatenation, Stepwise Adsorption Behaviors
ABSTRACT: Hydrogen-bonded organic frameworks (HOFs) show great potential in many applications, but few structure-property
correlations have been explored in this field. In this work, we report that self-assembly of a rigid and planar ligand gives rise to flat hexagonal
honeycomb motifs which are extended into undulated two dimensional (2D) layers and finally generate three polycatenated HOFs with record
complexity. This kind of undulation is absent in the 2D layers built from a very similar but non-planar ligand, indicating a slight torsion of ligand
produces overwhelming structural change. This change delivers materials with unique stepwise adsorption behaviors under a certain pressure
originating from the movement between mutually interwoven hexagonal networks. Meanwhile, high chemical stability, phase transformation,
and preferential adsorption of aromatic compounds were observed in these HOFs. The results presented in this work would help us to
understand the self-assembly behaviors of HOFs and shed light on the rational design of HOF materials for practical applications.
INTRODUCTION
Learning from the extensively existed hydrogen bonding in the
biological system, chemists were inspired to use hydrogen bonding
to construct porous frameworks, termed as hydrogen-bonded
The structures of HOFs were dominated by molecular building
blocks that mainly consist of two indispensable parts, namely a
backbone (or scaffold) and hydrogen bonding interaction.
9
organic frameworks (HOFs) or supramolecular-organic frameworks
Changing either of them would make great differences on the
obtained structure of materials. For example, self-assembly of the
1
(SOFs), as early as 1990s. This kind of materials has many unique
advantages including high crystallinity, large surface area, mild
ligand
4,4',4'',4'''-tetra(2,4-diamino-1,3,5-triazin-6-yl)tetra-
2
-6
synthetic conditions, solvent processability, and so on. However,
even after the efforts of several decades, the HOFs (including SOFs)
field is still under-development especially compared with the
prosperousness of its analogue of metal-organic frameworks (MOFs)
and covalent organic frameworks (COFs). One of the most
significant barriers can be ascribed to the poor chemical stability
originated from the weak non-covalent interactions. Apart from
stability, another obvious obstacle lies in that the design and
prediction of the obtained self-assembly structure is usually
unsuccessful, since the rules for self-assembly of HOF have yet to be
phenylethene (DAT-TPE) resulted two entirely different HOF
structures, where the dissimilarity was derived from the difference
on hydrogen bonding interaction.1 Therefore, understanding the
influence of both backbone geometry and the hydrogen bonding
interaction on the final structure is very important for unveiling the
self-assembly rules and realizing the rational design of HOF
structures. This encourages us to investigate ligands with identical
hydrogen interaction but different backbone geometry. Among
0-11
these, 4,4',4''-benzene-1,3,5-triyl-tris(benzoic acid) (H
3
BTB, also
called 1,3,5-tris(4-carboxyphenyl)benzene and abbreviated as
7-8
12
fully clear.
TCPB) and 4,4',4''-(1,3,5-tria-zine-2,4,6-triyl)-tribenzoic acid
TATB)13 (Figure 1)
(H
3
1
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 8
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 1. Representation of the chemical structure, the obtained hexagonal honeycomb motifs, the resulted monolayer and polycatenated networks
constructed by H
3 3
TATB (upper panel) and H BTB (lower panel). Atomic force microscope (AFM) and scanning electron microscope (SEM) images
of the solute in supernatant during the crystallization process (fifth and third days, respectively) of PFC-12 (inset).
attract our interests, because they are readily accessible and the
hydrogen interaction between the carboxyl groups on C symmetry
backbones can be easily predicted. The difference between these
two ligands lies on that H TATB is a planar molecule with
conjugated effect while H BTB is non-planar. The non-planarity of
BTB is induced by the slight dihedral angle between adjacent
benzene rings. The investigation of the structures assembled from
these two ligands would bring us a chance to unveil the factors
impacted on the final structure as well as the structure-properties
relationship in HOF materials.
resulted in flat H-bonded hcb layers with inclined polycatenation of
parallel layers.14 The entangled structures endow PFC-11 and 12
with high degree of flexibilities, and therefore expected gate opening
adsorption behaviors were observed. The π electrons of s-triazine
and phenyl rings on framework provide strong interactions toward
molecules with large π conjugation, causing higher uptakes for vapor
of benzene and toluene over cyclohexane. The carbon dioxide
3
3
3
H
3
14
12
uptakes are also among highest values for HOFs.
RESULTS AND DISCUSSION
Crystal Structure. PFC-11, 12 and 13 were obtained by
recrystallization of H TATB in ethyl alcohol, isopropanol and the
mixture of ethyl alcohol/deionized water, respectively (Scheme S2).
Single-crystal X-ray diffraction indicates that H TATB monomers in
3
In this work, based on the co-planar H TATB molecules, three
HOFs (PFC-11, PFC-12, and PFC-13) (PFC= Porous materials
from FJIRSM, CAS) have been synthesized from different solvents
3
(
Scheme S2) and characterized by single-crystal X-ray diffraction. In
these structures, adjacent H TATB ligands are interconnected
3
all these structures are interconnected through double hydrogen
bonds to form a hexagonal honeycomb motif of hcb topology, which
is a result of the symmetry of the ligand. Solvent information inside
3
through double hydrogen bonds to form regular hexagonal
honeycomb nets (hcb), which are interwoven simultaneously to
form extremely complicated two-dimensional (2D) layer structures.
Entanglement (interpenetration or polycatenation) stabilizes
structures due to increasing molecular packing density and adding
1
pores was determined by elemental analysis and H-NMR (Figure
3
S15-17). Notably, the layers constructed by H TATB ligands show
regular undulations and these wave-like layers are parallel
polycatenated, resulting in intricate crisscrossed 2D networks
1
5-16
more intermolecular interactions.
We also speculate that the
(
Figures 1 and 2). The very high undulation of layers in these
structures aroused our attention: the span of the layers in PFC-11,
2 and 13 are 49.3 Å, 37.7 Å, and 72.7 Å, respectively. Using Top-
undulations coupled with parallel polycatenation stabilize the ultra-
thin planar fragments formed during self-assembly process, which
resembles the microscopic corrugations existing on suspended or
1
23
1
7-20
osPro, we found in CSD only one example of H-bonded organic
supported graphene sheets.
observed in the HOF structure constructed by other flat molecules
of benzene-1,3,5-tricarboxylic acid H BTC (named also trimesic
Undulation of hcb nets can be also
hcb undulated layers that span more than 37 Å: the 1,3,5-triazine-
2
,4,6-triyltris(4,1-phenylene)triboronic acid with hcb topology
3
22
22
2
1
(OFUVUJ with a span of 53.9 Å). Such high waves have never
acid) and triboronic acid derivative. In contrast, self-assembly of
the non-planar H BTB molecules (CSD RefCode OGUROZ01)
3
2
ACS Paragon Plus Environment

Page 3 of 8
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 2. The geometry of entanglement (degree of catenation DOC referred to the red-arrow indicated red layer (a)) and of a single undulated layer
(
b) for PFC-11, PFC-12, PFC-13.
been observed in other layered H-bonded structures with flat
The origin of the undulation in 2D layered structure. The
occurrence of wave-like layers in all these structures, no matter what
temperature and solvent we used in the recrystallization process, was
reminiscent of the corrugations observed on suspended or
supported graphene sheets where the rippling has been invoked to
explain the thermodynamic stability of free-standing graphene
sheets.19 There were numerous studies on thin films showing that
films become thermodynamically unstable (segregated into islands
or decomposed) when the thickness is below a certain value, unless
they constitute an inherent part of a three-dimensional (3D) system,
1
4, 24-27
molecular building units.
Further looking into the detailed structure of PFC-11 to 13, we
found that the H TATB building units are almost planar molecule
3
(i.e. with deviation from planarity of max. 0.8 Å, see table S2) that
self-assembled into a nearly ideally planar hexagonal ring (Figure 1).
All the curvature happens on hydrogen interaction sites at interval of
specific connection of the hexagons as shown in Figure 2b: 4-3-3-3-
4-3-3-3 for PFC-11 (one step of four hexagons up alternating with
three steps of three hexagons down-up-down repeated twice), 3-3
such as grown on the surface of a bulk crystal with a matching
for PFC-12 (up and down steps of three hexagons), 6-6 for PFC-13
19, 28-29
BTC (BTCOAC)21
six hexagons up and down). Like PFC-12, H
3
lattice.
Therefore, we speculate that during the self-assembly
TATB molecules
(
process, the hexagonal motifs constructed by H
3
has 3-3 steps of hexagon connections but a smaller span of 25.8 vs
7.7 Å due to the smaller size of H BTC while the bigger triboronic
can undergo corrugation after exceeding certain dimension (an
undulation step), resulting in undulated layered fragments, or we
can say intermediates, which are interwoven simultaneously and
finally fixed by molecular packing in a bulk crystal. Moreover, as the
hydrogen bond interaction is much labile than the organic
3
3
2
2
acid derivative OFUVUJ has 4-4-3-3-4-4-3-3 steps with span 53.9
Å (Table S2).
3
ACS Paragon Plus Environment

Journal of the American Chemical Society
backbones with delocalization of π electrons, the deviation from
Page 4 of 8
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
planarity is manifested in the hydrogen bonding geometry. This
speculation is supported by the observation that the supernatant
solution contains many lamellae featured about 7 nm in thickness
when examined by AFM and SEM analyses, on the fifth and third
days during the crystallization process (from different batches, see
Figure 1, inset). It is worth to mention that undulated hcb were also
2
1
3
found in two HOFs built by H BTC (BTCOAC) and triboronic
2
2
acid derivative OFUVUJ , which are planar ligands as well. While in
a search of H-bonded hcb net built from tri-carboxylated ligands, we
found that non-planar ligands prefer inclined polycatenation of flat
hcb nets instead of corrugation (see Table S2). These findings
validate our speculation that hcb layers distorted by undulation and
parallel polycatenation provide higher density of molecular packing
and minimize the surface free energy during self-assembly process.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
Figure 3. Crystal structures of PFC-11, PFC-12 and PFC-13 showing
the shape of the cavities in green.
The intricated polycatenation in structures. The parallel
polycatenations in PFC-11, PFC-12, and PFC-13 have record
complexity and unique features, which have never been observed
2
5-27
before.
The three structures are new examples of entanglement
isomers with different solvents inside of pores and different topology
2
7
of rings catenations. In detail, in PFC-11 one layer (Figure 2a)
catenates 24 other layers (degree of catenation, DOC = 24), while
rings catenate 12 or 14 other rings (12, 14-c coordination of Hopf
ring net, HRN), it is required to remove 20 layers to disjoin the
entangled array on two separate parts (index of separation, IS = 20,
Figure S1). PFC-12 has DOC = 18, IS = 14, and 12-c HRN. Finally,
PFC-13 has the record largest DOC = 36 and IS = 35, while 12-c
coordination of HRN. The known records on polycatenation
complexity of H-bonded networks have been all observed for hcb
Figure 4. The composition of channel in structures of PFC-11 (a) and
PFC-12 (b). Balls of olive, red, grey and blue colour present hydrogen,
oxygen, carbon, and nitrogen atoms, respectively.
The pore architecture and gas adsorption performance. Despite
the presence of intricate polycatenation, there remains solvent-
accessible void spaces in PFC-11, PFC-12, and PFC-13, and which
are estimated to be 35.2%, 35.2%, and 34.6%, respectively, relative
to the whole crystal volumes. Further looking into these structures,
PFC-11 and PFC-12 obtained from less polar solvents ethyl alcohol
and isopropanol exhibit one-dimensional helical open channels,
2
1
underlying net and are H
3
BTC (BTCOAC) with DOC = 10, IS =
8, and 6-c HRN, bis(1,1,1-tris(4-hydroxyphenyl) ethane) tris(4,4'-
3
0
bipyridyl) (POVJAL) with DOC = 10, IS = 5, and 20-c HRN and
2
2
the triboronic acid derivative OFUVUJ with DOC = 31, IS = 24,
and 14-c HRN. Among coordination polymers, the most complex
polycatenation was observed again for hcb nets: DOC = 10, IS = 3,
3
1
32
1
2-c HRN (RIWXIG , VUHCUX ).
2
while PFC-13 obtained from the mixture of ethyl alcohol and H O
For comparison, we further looked into the structure of HOF-
BTB (with the same underlying net hcb), where the monolayers are
shows closed cavities (Figure 3). Thus, variation of synthesis
conditions (choice of solvent) enables tuning the pores geometry
and the connections of HOF materials.
flat and assembled in parallel stacks to form inclined polycatenated
3
D array (OGUROZ01).14 The existence of torsions between
The active surface in PFC-11 and PFC-12 should exhibit polarity
adjacent benzene rings of H
hexagonal motif with an obvious deformation out of plane (Figure
). In this case, we believe that the excess energy was consumed by
3
BTB ligands led to the observed
due to the triazine core and carboxylate oxygens in the ligand, as well
2
as sp carbon atoms from aromatic rings peeking out into the pores,
1
that enable stronger interactions with both carbon dioxide and
aromatic guest molecules. Thus, the open channels surface in PFC-
11 and PFC-12 is composed from H, O, C, N in the ratios
60.8:27.4:11.4:0.4 and 64.6:29.2:6.2:0, respectively; PFC-11 differs
the rotation of the peripheral phenyl groups (deviation from
planarity of max. 1.41 Å), therefore the generated 2D monolayers
23
were flat without undulation. In summary with ToposPro , we
found in CSD 12 examples of H-bonded networks, with underlying
hcb nets, from tripodal carboxylate molecules. They show flat
networks built from non-planar molecules assembled in inclined
polycatenated 3D array (Table S2), again coinciding with our
explanation on the origin of the undulated layers in PFC-11 to 13.
Therefore, a deviation on dihedral angles from planarity produces
the overwhelming structural changes observed in this work.
2
from PFC-12 by presence of N and larger part of sp carbon atoms
on the pore surface (Figure 4).
2 2
N isotherm shows that PFC-13 failed to load N after activation,
while both PFC-11 and PFC-12 exhibit stepwise adsorption
isotherms and obvious hysteresis behaviors in the desorption
isotherms.5 As shown in Figure 5a, PFC-11 and PFC-12 absorbed
, 33
3
3
2
N with uptake of 247 cm /g and 251 cm /g and Brunauer-Emmett-
2
2
Teller (BET) surface area of 751.3 m /g and 653.6 m /g,
respectively. The well-defined steps occur at low relative pressure
(
0 0
P/P < 0.09) and P/P = 0.36 during adsorption process. This
behavior usually associates with the swelling of non-rigid porous
4
ACS Paragon Plus Environment

Page 5 of 8
Journal of the American Chemical Society
structures or with irreversible adsorption of molecules in pores of
approximately the same size as the adsorbate. Obviously, the radius
of nitrogen molecule (1.82-1.90 Å) is much smaller than the pore
type usually observed in other HOF materials.4 However, the
, 8
3
3
1
2
3
4
5
6
7
8
9
2
values of CO uptake in PFC-11 of 90.3 cm /g and 65.1 cm /g under
pressure 1 atm are among the highest for reported HOFs at 273 K
3
4
size of PFC-11 (the maximal radius of migrating probe Rf = 2.76 Å
and radius of maximal pore Rfi = 4.07 Å) and PFC-12 (Rf = 3.26 Å
and Rfi = 3.69 Å) (Figure S4). Therefore, the second step of
0
isotherm at P/P = 0.36 can be ascribed to the movement between
mutually interspersed hexagonal networks under a certain pressure.
This movement can also explain the unclosed hysteresis loop
observed on the desorption branches. In the structure of PFC-11
and PFC-12, the apertures formed by movable polycatenated
networks change along with the pressure variation and trap
significant amount of adsorbate in pore space during the desorption
process. However, this stepwise adsorption behavior was not
observed in HOF-BTB as shown in Figure S5 and reference 14 and
and 298 K, respectively, higher values were obtained before only for
3
5
10, 12
HOF-5a.
2
The good CO adsorption capacity can be ascribed to
the presence of N and O atoms in the ligands and the H-bonding in
framework that polarize the pore surface and make host-guest
interactions stronger.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
36 (two channels along (010) with Rf = 2.76 Å, Rfi = 5.06 Å and Rf
=
2.96 Å, Rfi = 4.59 Å), where HOF-BTB displays type I isotherm
characteristic of microporosity as most periodic framework
materials do. Therefore, it’s reasonable to conclude that the wave-
like layer structure endows PFC-11 and 12 with high degree of
flexibility and special adsorption behavior.
Figure 6. (a) PXRD patterns of PFC-12, 13 and indicative of the
transformation from PFC-12 to 13 after being soaked in water. (b)
PXRD patterns of PFC-11 after being treated with different pH aqueous
solution.
Stability of PFC-11, 12 and 13. Powder X-ray diffraction (PXRD)
patterns of PFC-11, PFC-12, and PFC-13 after N adsorption are
2
almost identical to those of the pristine samples (Figures S7, S9 and
S12), indicating the porous architectures retained after undergoing
backbone movement during the adsorption process. Chemical
stability test of these compounds demonstrates that both PFC-11
and PFC-13 exhibit high water stability in aqueous solution from pH
0
to pH 11 as indicated by PXRD patterns (Figures 6b and S13).
Figure 5. (a) N
at 77 K. (b) CO
and 298 K.
2
adsorption isotherms of PFC-11, PFC-12 and PFC-13
2
adsorption isotherm of PFC-11 and PFC-12 at 273 K
Besides, the PXRD patterns of these HOFs still matched well with
the simulated patterns after being treated with some organic solvents,
such as CH OH, acetone, CH CN, and CH Cl for one day (Figures
3 3 2 2
S8, S10 and S12). Noted that PFC-12 was transformed to PFC-13
after being immersed in water for 24 hours as confirmed by PXRD
patterns (Figure 6a), indicating a tendency of transformation from a
The two porous materials were also tested for carbon dioxide
adsorption at temperatures 273 K and 298 K (Figure 5b). The
resulting isotherms do not show any steps and belong to classical
5
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 8
high porous structure into a close packing phase. As we mentioned
demonstrated that the slight deviation on dihedral angles in a ligand
delivers overwhelmingly changes on both the structure and the
property, which allows us to well understand the self-assembly rule
and the structure-property relationship for rational design of HOF
materials.
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
above, the variation of synthesis conditions (choice of solvent)
enables tuning the pore geometry and their connections. The degree
of catenation follows the order of PFC-12 (DOC = 18) <PFC-11
(DOC = 24) <PFC-13 (DOC = 36), which is consistent with the
ordered of solvent polarity and molecules dimensions used for
recrystallization: isopropanol (for PFC-12) < ethanol (for PFC-11)
ASSOCIATED CONTENT
The Supporting Information is available free of charge via the Internet
at http://pubs.acs.org.
Detailed information regarding the experimental methods,
syntheses, structure analysis, powder XRD patterns, vapor adsorption
<
ethanol and water (for PFC-13). Therefore, we inferred that the
solvent with higher polarity and smaller size produces more closely
packed structure. This trend also explains the phenomenon that
PFC-12 can transform to PFC-13 upon treating with water. Because
of the high complexity of the molecular packing, it is difficult to track
the structural transformation from PFC-12 to PFC-13. Indeed, the
transformation is provided by breaking the H-bonds (the Hopf ring
nets are different), as well the closing of pores in the PFC-12. Thus,
the stacks of 3 molecules of PFC-12 converts to 6 molecule stacks in
PFC-13 due to the shift of molecules respective to each other
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(PDF).
Crystallographic data of PFC-11 (CIF)
Crystallographic data of PFC-12 (CIF)
Crystallographic data of PFC-13 (CIF)
AUTHOR INFORMATION
Corresponding Author
(Figure S3).
Vapor adsorption. Inspired by the excellent stability and
* tfliu@fjirsm.ac.cn
* davide.proserpio@unimi.it
* wbyuan@hainanu.edu.cn
framework flexibility, the vapor adsorption capacities of PFC-11 and
PFC-12 toward benzene, toluene, and cyclohexane were
investigated. As shown in Figure S18, both PFC-11 and PFC-12
Author Contributions
3
have much higher adsorption uptakes of benzene (190.7 cm /g for
All authors have given approval to the final version of the manuscript.
Notes
The authors declare no competing financial interest.
3
3
PFC-11, 318.7 cm /g for PFC-12) and toluene (174.9 cm /g for
3
3
PFC-11, 183.7 cm /g for PFC-12) than cyclohexane (91.6 cm /g for
PFC-11, 86.5 cm /g for PFC-12). The preferential adsorption can
3
be described to the widely exposed π electrons of s-triazine rings in
ACKNOWLEDGMENT
L.T.F. thanks the financial support of National Key Research and
Development Program of China (grant No. 2018YFA0208600),
the channel, which can provide strong host-guest interactions
3
7-38
toward benzene and toluene molecules.
The lower adsorption
uptake of toluene than benzene can be described to the larger steric
“
Strategic Priority Research Program” of the Chinese Academy of
2
hindrance derived from the larger molecular area of toluene (55.3 Å )
Sciences (Grant No. XDB20000000). E.V.A. thanks Russian Science
Foundation (grant No. 18-73-10116) for financial support of
development of methods for topology analysis. D.M.P. thanks the
Università degli Studi di Milano for the transition grant PSR2015-1718
and FFABR2018. Y.W. would like to acknowledge the National Natural
Science Foundation of China (NSFC, grant no. 21561009) for financial
support.
2
34
than benzene (48.2 Å ). Because of the higher uptake of volatiles
for PFC-12, we can assume that it undergoes much larger structural
changes (the starting pores volume was about the same for both
0
compounds) upon adsorption at pressures more than 0.5 P/P . It is
also worth noting that both PFC-11 and PFC-12 can be recycled
through a heating procedure to completely remove the vapor guests
(Figures S19), demonstrating PFC-11 and PFC-12 are the
promising candidates for volatile organic compound adsorption and
separation with high stability and uptake.
ABBREVIATIONS
PFC = Porous materials from FJIRSM, CAS;
CAS = Chinese Academy of Sciences
DOC = degree of catenation
Conclusion
IS = index of separation
Based on planar H
1, 12, and 13, have been synthesized where H
3
TATB molecules, three HOF materials PFC-
TATB molecules are
1
3
REFERENCES
connected through double hydrogen bonds to form nearly ideal
hexagonal honeycomb motifs. Regular undulations were observed
when the hexagonal motifs were extended into a 2D layer, which
could be explained by the thermodynamic instability of the layers.
Wrinkled layers and entangled networks minimize the free energy
and stabilize the entire structure. In contrast, self-assembly of the
(1) Hisaki, I.; Nakagawa, S.; Ikenaka, N.; Imamura, Y.; Katouda, M.;
Tashiro, M.; Tsuchida, H.; Ogoshi, T.; Sato, H.; Tohnai, N.; Miyata, M., A
Series of Layered Assemblies of Hydrogen-Bonded, Hexagonal Networks of
C3-Symmetric pi-Conjugated Molecules: A Potential Motif of Porous
Organic Materials. J Am Chem Soc 2016, 138 (20), 6617-6628.
(
2) Hu, F.; Liu, C.; Wu, M.; Pang, J.; Jiang, F.; Yuan, D.; Hong, M., An
3
very similar ligand H BTB, bearing the same hydrogen bonding sites
Ultrastable and Easily Regenerated Hydrogen-Bonded Organic Molecular
Framework with Permanent Porosity. Angew Chem Int Ed 2017, 56 (8),
2101-2104.
(3) Yin, Q.; Zhao, P.; Sa, R. J.; Chen, G. C.; Lu, J.; Liu, T. F.; Cao, R., An
Ultra-Robust and Crystalline Redeemable Hydrogen-Bonded Organic
Framework for Synergistic Chemo-Photodynamic Therapy. Angew Chem
Int Ed 2018, 57 (26), 7691-7696.
but non-planar backbone, resulted in a flat monolayer. The unique
interweaving structures of PFC-11, 12 and 13 endow materials with
high degree of flexibility and stepwise adsorption behavior. With the
excellent stability and framework flexibility, PFC-11 and 12 present
promising candidates for carbon dioxide and volatile organic
compound adsorption with preferential selectivity toward π-
conjugated molecules such as benzene and toluene. This work
(
4) Lu, J.; Cao, R., Porous Organic Molecular Frameworks with Extrinsic
6
ACS Paragon Plus Environment

Page 7 of 8
Journal of the American Chemical Society
Porosity: A Platform for Carbon Storage and Separation. Angew Chem Int
Ed 2016, 55 (33), 9474-9480.
5) Yin, Q.; Li, Y. L.; Li, L.; Lu, J.; Liu, T. F.; Cao, R., Novel Hierarchical
Meso-Microporous Hydrogen-Bonded Organic Framework for Selective
Separation of Acetylene and Ethylene versus Methane. ACS Appl Mater
Interfaces 2019, 11 (19), 17823-17827.
(23) Blatov, V. A.; Shevchenko, A. P.; Proserpio, D. M., Applied
Topological Analysis of Crystal Structures with the Program Package
ToposPro. Crystal Growth & Design 2014, 14 (7), 3576-3586.
(24) Chen, T. H.; Popov, I.; Kaveevivitchai, W.; Chuang, Y. C.; Chen, Y.
S.; Daugulis, O.; Jacobson, A. J.; Miljanic, O. S., Thermally robust and
porous noncovalent organic framework with high affinity for fluorocarbons
and CFCs. Nat Commun 2014, 5, 5131.
(25) Zolotarev, P. N.; Arshad, M. N.; Asiri, A. M.; Al-amshany, Z. M.;
Blatov, V. A., A Possible Route toward Expert Systems in Supramolecular
Chemistry: 2-Periodic H-Bond Patterns in Molecular Crystals. Crystal
Growth & Design 2014, 14 (4), 1938-1949.
1
2
3
4
5
6
7
8
9
(
(
6) Patil, R. S.; Banerjee, D.; Zhang, C.; Thallapally, P. K.; Atwood, J. L.,
Selective CO Adsorption in a Supramolecular Organic Framework. Angew
Chem Int Ed 2016, 128 (14), 4599-4602.
7) Hisaki, I.; Xin, C.; Takahashi, K.; Nakamura, T., Designing
2
(
Hydrogen-Bonded Organic Frameworks (HOFs) with Permanent Porosity.
Angew Chem Int Ed 2019,58(33), 11160-11170.
(26) Carlucci, L.; Ciani, G.; Proserpio, D. M.; Mitina, T. G.; Blatov, V. A.,
Entangled two-dimensional coordination networks: a general survey. Chem
Rev 2014, 114 (15), 7557-7580.
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(8) Lin, R. B.; He, Y.; Li, P.; Wang, H.; Zhou, W.; Chen, B.,
Multifunctional porous hydrogen-bonded organic framework materials.
Chem Soc Rev 2019, 48 (5), 1362-1389.
(27) Alexandrov, E. V.; Blatov, V. A.; Proserpio, D. M., How 2-periodic
coordination networks are interweaved: entanglement isomerism and
polymorphism. Crystengcomm 2017, 19 (15), 1993-2006.
(28) Zinke-Allmang, M.; Feldman, L. C.; Grabow, M. H., Clustering on
surfaces. Surface Science Reports 1992, 16 (8), 377-463.
(29) Evans, J. W.; Thiel, P. A.; Bartelt, M. C., Morphological evolution
during epitaxial thin film growth: Formation of 2D islands and 3D mounds.
Surface Science Reports 2006, 61 (1-2), 1-128.
(30) Bényei, A. C.; Coupar, P. I.; Ferguson, G.; Glidewell, C.; Lough, A.
J.; Meehan, P. R., Tenfold Interpenetration of Giant HexagonalR1212(126)
Nets in the Hydrogen-Bonded Structure of 1,1,1-Tris(4-
hydroxyphenyl)ethane–4,4'-Bipyridyl (2/3). Acta Cryst 1998, E54 (10),
1515-1519.
(31) Jiang, X.; Li, Z.; Zhai, Y.; Yan, G.; Xia, H.; Li, Z., Porous coordination
polymers based on azamacrocyclic complex: syntheses, solvent-induced
reversible crystal-to-crystal transformation and gas sorption properties.
CrystEngComm 2014, 16 (5), 805-813.
(32) Yang, Q. Y.; Zheng, S. R.; Yang, R.; Pan, M.; Cao, R.; Su, C. Y., An
unusual 3D coordination polymer assembled through parallel
interpenetrating and polycatenating of (6,3) nets. CrystEngComm 2009, 11
(4), 680-685.
(33) Burtch, N. C.; Jasuja, H.; Walton, K. S., Water stability and
adsorption in metal-organic frameworks. Chem Rev 2014, 114 (20), 10575-
10612.
(34) Li, J. R.; Kuppler, R. J.; Zhou, H. C., Selective gas adsorption and
separation in metal-organic frameworks. Chem Soc Rev 2009, 38 (5), 1477-
1504.
(35) Blatova, O. A.; Golov, A. A.; Blatov, V. A., Natural tilings and free
space in zeolites: models, statistics, correlations, prediction. Z Krist-Cryst
Mater 2019, 234 (7-8), 421-436.
(
9) Han, Y. F.; Yuan, Y. X.; Wang, H. B., Porous Hydrogen-Bonded
Organic Frameworks. Molecules 2017, 22 (2), 266.
10) Wang, H.; Li, B.; Wu, H.; Hu, T. L.; Yao, Z.; Zhou, W.; Xiang, S.;
(
Chen, B., A Flexible Microporous Hydrogen-Bonded Organic Framework
for Gas Sorption and Separation. J Am Chem Soc 2015, 137 (31), 9963-
9970.
(11) Wang, H.; Bao, Z.; Wu, H.; Lin, R. B.; Zhou, W.; Hu, T. L.; Li, B.;
Zhao, J. C.; Chen, B., Two solvent-induced porous hydrogen-bonded
organic frameworks: solvent effects on structures and functionalities. Chem
Commun 2017, 53 (81), 11150-11153.
(12) Yang, W.; Zhou, W.; Chen, B., A Flexible Microporous Hydrogen-
Bonded Organic Framework. Crystal Growth & Design 2019, 19 (9), 5184-
5188.
(13) Muhlbauer, E.; Klinkebiel, A.; Beyer, O.; Auras, F.; Wuttke, S.;
Luning, U.; Bein, T., Functionalized PCN-6 metal-organic frameworks.
Microporous and Mesoporous Materials 2015, 216, 51-55.
(14) Zentner, C. A.; Lai, H. W.; Greenfield, J. T.; Wiscons, R. A.; Zeller,
M.; Campana, C. F.; Talu, O.; FitzGerald, S. A.; Rowsell, J. L., High surface
area and Z' in a thermally stable 8-fold polycatenated hydrogen-bonded
framework. Chem Commun 2015, 51 (58), 11642-11645.
(15) Baburin, I. A.; Leoni, S., Modelling polymorphs of metal–organic
frameworks: a systematic study of diamondoid zinc imidazolates.
CrystEngComm 2010, 12 (10), 2809-2816.
(
16) Alexandrov, E. V.; Blatov, V. A.; Proserpio, D. M., Interpenetration
of three-periodic networks in crystal structures: Description and
classification methods, geometrical-topological conditions of
implementation. Journal of Structural Chemistry 2015, 55 (7), 1308-1325.
17) Stöberl, U.; Wurstbauer, U.; Wegscheider, W.; Weiss, D.; Eroms, J.,
(
Morphology and flexibility of graphene and few-layer graphene on various
substrates. Applied Physics Letters 2008, 93 (5), 051906.
(36) Yoon, T. U.; Baek, S. B.; Kim, D.; Kim, E. J.; Lee, W. G.; Singh, B.
K.; Lah, M. S.; Bae, Y. S.; Kim, K. S., Efficient separation of C2 hydrocarbons
in a permanently porous hydrogen-bonded organic framework. Chem
Commun 2018, 54 (67), 9360-9363.
(37) Huang, Y.; Lin, Z.; Fu, H.; Wang, F.; Shen, M.; Wang, X.; Cao, R.,
Porous anionic indium-organic framework with enhanced gas and vapor
adsorption and separation ability. ChemSusChem 2014, 7 (9), 2647-2653.
(38) Liu, T. F.; Lu, J.; Lin, X.; Cao, R., Construction of a trigonal bipyramidal
cage-based metal-organic framework with hydrophilic pore surface via flexible
tetrapodal ligands. Chem Commun 2010, 46 (44), 8439-8441.
(18) Meyer, J. C.; Geim, A. K.; Katsnelson, M. I.; Novoselov, K. S.; Booth,
T. J.; Roth, S., The structure of suspended graphene sheets. Nature 2007,
446 (7131), 60-63.
(
19) Lui, C. H.; Liu, L.; Mak, K. F.; Flynn, G. W.; Heinz, T. F., Ultraflat
graphene. Nature 2009, 462 (7271), 339-341.
20) Fasolino, A.; Los, J. H.; Katsnelson, M. I., Intrinsic ripples in
graphene. Nat Mater 2007, 6 (11), 858-861.
21) Duchampt, D. J.; Marsh, R. E., The Crystal Structure of Trimesic
(
(
Acid (Benzene-l, 3, 5-triearboxylic Acid). Acta Cryst 1969, B25, 5-19.
(22) Sarkar, K.; Dastidar, P., Supramolecular Hydrogel Derived from a
C3-Symmetric Boronic Acid Derivative for Stimuli-Responsive Release of
Insulin and Doxorubicin. Langmuir 2018, 34 (2), 685-692.
Table of Contents (TOC)/Abstract Graphic
7
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 8
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
COOH
N
N
N
HOOC
COOH
H
3
TATB
stepwise
O
O
H
O
O
COOH
H
Pressure
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
HOOC
COOH
3
H BTB
85
ACS Paragon Plus Environment