The structures of MOFs prepared from 1,3,5-tris [4-pyridylethynyl]-benzene and a copper(I) perchlorate complex

Article abstract of DOI:10.1002/jccs.201900022

Two copper(I)-based frameworks of complexes {[Cu(L)₂(ClO₄)]?CH₃CN}(2) and {[Cu(L)(ClO₄)]? 2CH₃CN} (3) (L = 1,3,5-tris(4-pyridylethynyl) benzene) were produced by reacting [Cu(MeCN)₄(ClO

Full text of DOI:10.1002/jccs.201900022

Received: 15 January 2019
Revised: 9 May 2019
Accepted: 10 May 2019
DOI: 10.1002/jccs.201900022
S P E C I A L I S S U E P A P E R
The structures of MOFs prepared from 1,3,5-tris
[4-pyridylethynyl]-benzene and a copper(I) perchlorate complex
En-Che Yang1
| Chen-Ming Wu1 | Pei-Jia Pan1 | Gene-Hsiang Lee2
|
Hwo-Shuenn Sheu3 | Chung-Kai Chang3
1Department of Chemistry, Fu Jen Catholic
University, New Taipei City, Taiwan
Abstract
2Instrumentation Center, College of Science,
National Taiwan University, Taipei, Taiwan
3National Synchrotron Radiation Research
Center Hsinchu Science Park, Hsinchu,
Taiwan
Two copper(I)-based frameworks of complexes {[Cu(L)2(ClO4)]ÁCH3CN}(2) and
{[Cu(L)(ClO4)]Á 2CH3CN} (3) (L = 1,3,5-tris(4-pyridylethynyl) benzene) were
produced by reacting [Cu(MeCN)4(ClO4)] with different amounts of a ligand
(L) using a hydrothermal method at temperatures of up to 130ꢀC. The nitrogen
atoms in the pyridine moieties of the ligand coordinate to the Cu(I) ion. The charge
on the Cu(I) ion can be stabilized by extending the degree of conjugation in the
system and by taking advantage of its highly symmetrical structure. The large
degree of conjugation also supports numerous π–π interactions in the framework.
Correspondence
En-Che Yang, Department of Chemistry, Fu
Jen Catholic University, Hsinchuang, New
Taipei City 24205, Taiwan, Republic of
China.
Email: 071549@mail.fju.edu.tw
K E Y W O R D S
π–π interactions, interpenetrating, MOF
Funding information
Ministry of Science and Technology,
Taiwan, Grant/Award Number:
MOST106-2113-M-030-008
and rigidly, and because the negative charges on the oxygen
atoms can be balanced with positive charges on metal ions,
1 | INTRODUCTION
Metal–organic frameworks (MOFs) have become an impor-
tant topic in chemistry due to their wide application in gas
storage,[1] chromatography,[2] heterogeneous catalysis,[3]
chemical sensing,[4] fluorescence,[5] and drug delivery.[6] In
addition to these extensive applications, the discovery of
MOFs with new structures is itself a great challenge in crys-
tal engineering as most new frameworks are produced by
self-assembly. Fine tuning the reaction conditions can some-
times have a profound influence on the final structure as well
as the properties of the final product. Based on a review of
the history of this subject, MOFs can be classified as
(a) strongly linked materials that are largely ligated by the
oxygen atoms of carboxylic acids, (b) weakly linked mate-
rials that include MOFs containing coordinated, nitrogen-
containing compounds (pyridine and derivatives thereof). A
recent review article concluded that because carboxylic
groups coordinate complexes that bind metal ions tightly
large MOF structures can be formed without the anion being
held in the channel of the complex. On the other hand,
because pyridine complexes bind weakly with metal ions,
supramolecular structures are typically formed. Among the
carboxylic acid-coordinated compounds, benzene-1,-
3,5-tricarboxylic
acid
(H3BTC)
and
benzene-1,-
4-dicarboxylic acid (H2BDC) are two typical examples.
They both form secondary building units (SBUs) or MOFs
with efficient gas absorption properties. In particular, both
findings that the H3BTC combines Cu to give HKUST-1,[7]
and that H2BDC combines with Zn to produce MOF-5[8]
triggered a series of studies of these materials for use in gas
storage.
Some successful cases have been reported in which the
pyridine-coordinated ligands with a three-fold C3 symmetry
can be applied to some functional organic site FOCs. Fol-
lowing this route, a new ligand referred to as 1,3,5-tris
© 2019 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J Chin Chem Soc. 2019;1–8.
http://www.jccs.wiley-vch.de
1

2
YANG ET AL.
(pyridine-4-ylethynyl) benzene (L, see Scheme 1) was first
developed by Prof. Sanders and his coworkers in 1995.[9]
Thereafter, a series of supramolecules synthesized using L
have been published by Prof. Peter J Stang.[10] In 2006, this
ligand was used by Prof. Edwin Weber along with some
hexafluoroacetylacetonate (hfacac) derivatives to synthesize
a two-dimensional coordination polymer.[11] Prof. Schmittel
et al. then used a similar ligand 1,3,5-trimethyl-2,4,6-tris
(4-pyridylethynyl)benzene to bind Cu(II) ions and form a
number of different supramolecules.[12] Furthermore, the
self-assembled structure and computational chemistry of
ligand (L) was reported and the results indicated the exis-
tence of hydrogen bonding, and a special arrangement of
atoms at the solid–liquid interface.[13] MOFs that are pre-
pared using only L have not been reported. In the current
article, we report on the preparation of and structures of two
new pure ligand L-linked Cu(I) MOFs, where complex
2 was prepared using L and cuprous ions in a 3:4 ratio, with
a [4 + 2] mutual penetration structure being produced. MOF
3, however, was isolated in a similar reaction, but using a
ligand L to cuprous ion ratio of 11:1, resulting in the forma-
tion of a [3 + 3] penetration structure.
conjugated system displays a variety of π–π interactions that
are mutually penetrating stabilizing the layered structure.
Ligands that are used to prepare MOFs can be roughly
classified into three categories according to Stang et al. sur-
vey of 2013.[15] They are (a) supramolecular coordination
complexes (SCC), (b) SCC and MOFs, and (c) MOFs that
contain a ligand “L” as its pyridine sites providing weak
linkages between metal ions, and are classified into the SCC
category. Nevertheless, when a low charge metal ion center
Cu(I) with a lower coordination number is used, a variety of
different MOFs' framework is formed. The metal ion source
used in this study was [Cu(MeCN)4(ClO4)]. Scheme 2
shows the synthetic strategies that were used in this study,
where in the first route, a 3:4 metal to ligand ratio was used
and the reaction was conducted in a sealed tube at 130ꢀC for
3 days. The second route used a metal to ligand ratio of 11:1
and was also heated in a sealed tube at 130ꢀC for 3 days.
Both conditions give different three dimensional MOF
frameworks. The extended conjugated system of the ligand
L with a variety of π–π stacking forces leads to the formation
of different types of interpenetrating networks, with layered
structures. Structural data obtained for these materials are
discussed below.
2 | RESULTS AND DISCUSSION
2.1 | Ligand and synthesis
2.2 | Structural analysis and discussion
Both MOFs were characterized using X-ray crystallography.
Their experimental conditions are summarized in Table 1.
The ligand used in this article is 1,3,5-tris(4-pyridylethynyl)
benzene that is abbreviated as “L”. The synthesis of this
ligand was developed by Masashi Kijima et al.[14] The most
important aspect of the synthesis of the ligand is that the pro-
cedure is air-sensitive. Any leakage in the Schlenk line can
cause a dramatic drop in the yield of the product. To avoid
damage caused by minor impurities in the nitrogen gas, the
use of an argon atmosphere is suggested in this reaction. The
ligand produced is quite stable in air. The ligand possesses a
regular triangle planar geometry with an extensive conju-
gated system and three pyridines. The regular triangle geom-
etry facilitates the formation of facets of polyhedrons. The
2.2.1 | {[Cu(L)2(ClO4)]ÁCH3CN}n (2)
Compound 2 crystallizes in a triclinic space group of P1 and
the repeating unit per unit cell contains one Cu(I) ion, two
crystallographically distinguishable ligands, one perchlorate
as the counter ion, and one acetonitrile molecule as the pack-
ing solvent whose formula is given as [Cu(L)2(ClO4)]Á
CH3CN. All of the Cu(I) ions have tetrahedral coordination
environments that are ligated to four pyridine groups that
ꢀ
SCHEME 1 Ligand (L) simplfied in topology structure of the
SCHEME 2 Synthetic procedure for preparing the two
ligand (L)
complexes

YANG ET AL.
3
TABLE 1 Crystal data and structure refinement
Identification code
Empirical formula
Formula weight
Crystal system
(2)
(3)
C
56H33ClCuN7O4
C31H21ClCuN5O4
626.52
966.88
Triclinic
P-1
Orthorhombic
Pna21
Space group
Unit cell dimensions
a = 11.0963(6)Å
α = 88.6860(18)ꢀ
b = 12.1939(7)Å
β = 73.5469(18)ꢀ
c = 17.8188(9)Å
γ = 86.699(2)ꢀ
a = 16.9224(11) Å
α = 90ꢀ
b = 29.1720(19)Å
β = 90ꢀ
c = 7.2751(5)Å
γ = 90ꢀ
Z
2
4
D (mg/m3)
1.391
1.159
Absorption coefficient (mm−1
)
0.588
0.719
F(000)
992
1,280
Theta range for data collection
Index ranges
2.384 to 25.000ꢀ
2.407 to 27.500ꢀ
−13 ≤ h ≤ 13
−14 ≤ k ≤ 14
−21 ≤ l ≤ 21
−20 ≤ h ≤ 21
−37 ≤ k ≤ 37
−9 ≤ l ≤ 9
Reflections collected
16,145
25,689
Independent reflections
Max. and min. Transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2sigma(I)]
R indices (all data)
8,124 [R(int) = 0.0102]
0.7452, 0.7196
8,044 [R(int) = 0.0369]
0.7456, 0.6802
8,124/20/664
8,044/73/398
1.043
1.159
R1 = 0.0561, wR2 = 0.1566
R1 = 0.0621, wR2 = 0.1627
R1 = 0.0712, wR2 = 0.1963
R1 = 0.0757, wR2 = 0.1991
arise from different ligands. Details of the coordination
mode can be seen in Figure 1(a). The observed copper–
nitrogen bond lengths are in the range of approximately
2.003–2.074 Å. In the meantime, two crystallographically
distinguishable ligands have the same coordination pattern,
which is illustrated in Figure 1(b). Each ligand has a ligating
mode of μ2-bridging coordinating to two Cu(I) ions from
two different pyridines, respectively. The remaining pyridine
group then acts as the dangling arm, as shown in
Figure 1(b).
It can also be seen from Figure 1(b) that the ligand L
ligates in a quite special coordination pattern. The Cu(I) ions
form pleated wrinkles with a two-dimensional (4,2) grid
structure. The topography contains dangling arms on both
sides of the grid plane. The network has Cu(I)–Cu(I) ions on
the 16.0 × 16.9 Å grid surface. It is important to note that
the interpenetrating holes have the same size in the network.
The final result is that the two crimp planes are self-
interpenetrating with respect to each other to form a thick
double layer. A detailed plot of this aspect can be seen in
Figure 2(a) and (b), which indicates the pyridine groups are
double interpenetrating wove in the grid network. It is also
quite important that the arms are dangling on both sides of a
double-layer interpenetrating grid. The arms act as an adhe-
sive and form perfect π–π interactions with the pyridine
functional groups that are adjacent to the double inter-
penetrating grid, which is illustrated in Figure 2 (c). The
FIGURE 1 (a) Copper-centered structure showing the
coordination mode for compund 2. (b) Compound 2 grid showing
copper–copper distance

4
YANG ET AL.
TABLE 2 Summary of topological analysis based on
TOPOSPRO
Crystal
2
3
Crystal
system
Triclinic
Orthorhombic
Space
group
P-1
Pna21
Formula
Grid
[Cu(L)2(ClO4)] CH3CN
[Cu(L)(ClO4)]Á2CH3CN
Hexagon
Octet
(4,2)
Node
(3,3)
TOPOSpro
build
The topospro analysis
shows that, Schälfli
symbols, the
There are four planes
mutually penetrating
in a [2 × 2] form.
They form a spiral
shape along the C-
axis, repeating for
every 7.28 Å.
[0,0,1] (7.28 A)
-----------------
NISE: Nontranslating
interpenetration
symmetry elements
-----------------
Cu(I) center of
compound (2) has
four 12-member
loops 124 (12 of
nodes in shortest
loop, four times of
loop) and two
18-member loops,
182
--------------------
Point symbols for net:
{0}2{124.182}
FIGURE 2 (a) Topology structure of compound 2, blue and red
represent different layers, (b) topology side view shows that each of the
two layers are interpenetrating. (c) Interpenetrating groups composed of
two layers (blue and red), and different types of pyridine-pyridine π–π
interactions
1:2(1)[0,0,1]
-----------------
{3.12.13}4{3}2 point
symbols for net with
loops: {124.182}
{3.12.13}4{3}4
1,3,3,4-c net with
stoichiometry (1-c)2
(3-c)4(3-c)2(4-c);
4-nodal net
ΠC: [0,0,2][1,0,1]
[1,1,0] (ΠCVR = 2)
Zt = 2; Zn = 2
adjacent double-layer interpenetrating grid planes accumu-
late in the self-assembly to form a perfect supramolecular
grid thin wall. The grids are separated by a distance that is
sufficient to accommodate perchlorate ions.
Class IIIa Z = 4[2 × 2]
The network of compound 2 is further analyzed using
program ToposPro that provides structure extension analysis
and simplification.[16] The autoCN module was used after
reading the crystal coordinates of the binding atoms and con-
sidering the hydrogen bonding when the new bond is added.
The auto mode was then used to determine a simplified adja-
cent matrix to simplify the structure and delete the atoms.
This left only atoms that contain more than two bonds with
the nonlinear bonding atoms being removed. All hydrogens
and carbon-bonded hydrogens, sp2 carbons, sp hybridized
carbons were deleted. Finally, an ADS analysis was carried
out for the full molecule with Schläfli symbol and topo-
graphical analysis. The results of the products (2) and (3) are
summarized in Table 2, which show compound 2 has an
octet grid with (4,2) nodes. And there are four 124 loops
(12 nodes in shortest loops, 4 loops) and two 18 loops (182)
at each Cu(I) center.
indistinguishable L ligands but can be regarded as one L
ligand per repeating unit and two acetonitrile molecules in
the crystallographic repeating unit. This gives a formula of
{[Cu(L)(ClO4)]Á2CH3CN}n. In compound 3, each Cu (I) has
a planar triangular geometry, connecting three different L
ligands, which are displayed in Figure 3(a). Each L unit
adopts a μ3-bridge mode and coordinates with three different
Cu (I) ions, respectively. The copper–nitrogen bond lengths
2.2.2 | [Cu(L)(ClO4)]Á2CH3CN (3)
Compound 3 crystallized in an orthorhombic space group,
Pna21, which contains one copper monovalent ion Cu(I),
one perchlorate ion as the counter ion, and three
FIGURE 3 (a) Copper-centered structure showing the
coordination mode, (b) copper-centered structure showing the Cu–N
bond lengths

YANG ET AL.
5
are in the range of 1.9537 to 2.0203 Å. The ligand with a
bond length of 2.0203 Å forms a twist angle with the other
two ligands. This arrangement is shown in Figure 3(b).
The three Cu(I) ions ligated in the same μ3-L have
CuÁÁÁCu distances of 16.7694, 17.7780, and 18.4200 Å,
respectively (see Figure 4(a)). This arrangement is quite dif-
ferent from the two-dimensional, infinitely extended hexago-
nal honeycomb formed by the general (3,3) network. The
three Cu(I)–Cu(I) and the three L units form a spiral shape at
an angle of 60ꢀ along the C-axis and overlap with another
Cu(I) ion in the C-axis to form a unique three-dimensional
honeycomb structure. The structure is very similar to the
quadruple helix along the C-axis in a DNA structure in
which the network forms hexagon helices that are separated
by a distance of 14.5502 Å along the C-axis, as illustrated in
Figure 4(b). Here, each honeycomb structure that is formed
along the C-axis will have two parallel L-planes and one
twisted L plane. After using the TOPOSPRO program to
simplify the structure, the results show that this material has
FIGURE 5 (a) Structure of compound (3), as simplified by the
ToposPro program. (b) C-axis view showing the position of acetonitrile
molecules and perchlorate ions
Bz form a Py–Bz (+) π–π stacking, the orange Py and green
Bz are involved in Py–Bz (−)π–π stacking. Each L ligand
has a pyridine ring above and below, leading to positive and
negative PyÁÁÁBz π–π interactions. The remaining Py forms
π–π interactions with the alkynyl moieties of two other
ligand layers, causing the layers to overlap at nearly the
same distance to form a relatively stable three-dimensional
structure. The structural analysis based on the ToposPro pro-
gram gave a hexagon grid with (3,3) nodes. There are four
interpenetrating planes, in the form of 2 × 2 planes in
a
three-dimensional honeycomb structure. The three-
dimensional pores are formed by the interpenetrating six-
ring honeycomb structure. In this self-assembly synthesis,
up to four single-layer structures are possible. Each layer is
separated from the next layer by 14.5502 Å along the C-
axis. Based on the simplified structure obtained by using the
ToposPro program, we also conclude from Figure 5(a) that
the spiral extension plane forms a unit. In this three-
dimensional honeycomb structure, each Cu(I) ion is related
to two acetonitrile molecules. The closest distance between
the Cu(I) ions and perchlorate ions is 5.626 Å. This means
that every three copper ions form a spiral honeycomb unit
that contains six acetonitrile molecules and three perchlorate
ions, as shown in Figure 5(b).
(a)
Because this ligand (L) contains four aromatic rings,
strong π–π stacking with the adjacent two layers of ligand L
was displayed. A detailed image of the π–π stacking is
shown in Figure 6(a).
(b)
Hereafter, the term Py is used to denote a pyridine unit
and Bz a benzene ring.[17] In Figure 6, the blue Py and green
FIGURE 6 (a) Blue Py and green Bz form py–Bz (+), π–π
distance is 3.303 Å, orange Py and green Bz are with py–Bz (−)π–π
stacking of 3.348 Å, Py forms π–π interactions with alkynyl moieties
of two other layers ligands with distances of 3.610 and 3.672 Å. (b) the
topos view shows four interpenetrating planes
FIGURE 4 (a) L-centered indicates μ3-coordination in compound
3, (b) bond length between copper without the same plan

6
YANG ET AL.
Figure 6(b), spiraling up the C-axis that are repeated at an
interval of 7.28 Å.
Table 2 shows the summary of topological analysis based
on TOPOSPRO.
2.3 | Elemental analysis of compound (3)
It should be noted here that the elemental analysis for
compound (3) was not very reproducible. This can be
attributed to the fact that the guest acetonitrile molecule is
easily lost from the complex, even at room temperature.
To determine the solvent loss behavior, thermogravimetric
analyses (TGA) were performed and the results are shown
in Figure 7. It can be seen that the solvent loss can occur
at temperatures lower than 50ꢀC. The mass decreases with
increasing temperature up to 150ꢀC and then reaches the
first plateau. Solvent loss is estimated to be two acetoni-
trile guest molecules per unit of complex, making a
weight loss of 86.7%. However, the experimental data
indicate a loss of 93.9%. This must be due to the loss of
solvent molecules during the interval between removing
the sample from the mother liquid but before inserting it
in the TGA chamber.
The integrity of the bulky sample was confirmed by
powder X-ray diffraction measurements carried out using
the mother liquor. Figure 8 shows a comparison between
the experimental data (upper) and a theoretical simulation
based on single crystal data (bottom). Except for the base
line caused by the mother liquid, the simulated values and
the experimental data are in quite good agreement. This
result strongly indicates two points: (a) the bulk sample is
pure and (b) the sample is quite stable in the mother
liquid.
FIGURE 8 Powder X-ray diffraction patterns of compound (3)
obtained using the mother liquid (λ = 0.826 nm)
3 | EXPERIMENTAL
All the chemicals were of commercial grade and were used
without further purification.
3.1 | [Cu(MeCN)4(ClO4)] (1)
Cu(ClO4)2Á5H2O (1.5 g, 5.93 mmol) was dissolved in
50.0 mL of MeCN and 0.75 g (11.81 mmol) powdered ele-
mental copper was then added to the solution. The mixture
was heated at 60ꢀC for 30 min and then filtered while the
solution was still hot. The resulting filtrate was stored in a
refrigerator overnight, resulting in the formation of colorless
crystals (1). IR spectrum(KBr cm−1): 3,437(m), 2,926(w),
2,268(w), 2,016(m), 1,625(m), 1,385(w), 1,366(w), 1,145
(s), 1,114(s), 1,086(s), 946(m) 699(w), 636(m), and 625
(s) (elemental analysis: exp. [calc.], C29.34% [29.55%],
N17.11% [17.17%], and H3.67% [3.70%]).
3.2 | 1,3,5-tris(4-pyridylethynyl)benzene (L)
CuI (100 mg, 0.52 mmol), Pd(PPh3)4 (600 mg, 0.52 mmol),
1,3,5-triethynylbenzene (1.3 g, 8.6 mmol), and
4-bromopyridine hydrochloride (7.6 g, 39.0 mmol) were
placed in a round bottom flask under an atmosphere of
argon. A solution of 100 mL of tetrahydrofurane (THF) and
50 mL of triethyl amine (Et3N) was placed in a second flask
under an atmosphere of argon. The solutions were then
mixed with one another and stirred at ambient temperature
for 24 hr under argon. The resulting solution was heated at
50ꢀC for 24 hr and then evaporated to dryness, after which,
150 mL of CH2Cl2 was added and the solution was shaked
FIGURE 7 Thermogravimetric analysis (TGA) of compound (3)

YANG ET AL.
7
by ultrasound wave for 30 min. The resulting solution was
washed three times with 150 mL of distilled water and the
resulting product was then purified by silica gel chromatog-
raphy by elution with CH2Cl2:EA = 1:2 to give 2.7 g of a
pale yellow product, yield = 82%. IR spectrum (KBr cm−1):
3,431(s), 3,035(s), 2,889(w), 2,431(w), 2,216(m), 1,938(w),
1,848(w), 1,774(w), 1,596(s), 1,539(m), 1,490(m), 1,407(s),
1,321(w), 1,286(w), 1,215(s), 1,123(w), 1,091(w), 1,067(w),
990(m), 968(m), 926(w), 882(s), 833(s), 819(s), 744(s), 681
(s), 610(w), 544(s), and 527(s); 1H NMR (300 MHz,
CDCl3): δ = 7.38 (d, 6H), δ = 7.74 (s, 3H), δ = 8.63 (d,
on
a
Perkin Elmer 1,600 spectrometer in the
450–4,000 cm−1 range. The elemental analysis and mass
spectroscopy were conducted at Instrumentation Center,
College of Science, National Taiwan University. The pow-
der X-ray diffraction was carried out at National Synchro-
tron Radiation Research Center.
3.6 | X-ray crystallography
Good quality crystals of compounds 2 and 3 were selected
and mounted on the tip of a glass fiber. A Bruker Kappa
4CCD diffractometer was employed that was equipped with
graphite monochromatic Mo Kα radiation (λ = 0.71073).
The temperature was maintained at 150 K by an Oxford
Cryosystems Cryostream Cooler. The area detector was
located at a distance of 5.00 cm from the crystal. Data reduc-
tion was done by the multiscan method using the HKL
SCALEPACK. Empirical absorption correction was done
using the SADABS program.[18] The structural analysis was
performed on a personal computer using the SHELXTL pro-
gram package. The structures were solved by the SHELXS-
97 program[19] and further refined by the Shelxl-97 program
using full matrix least-square fitting of F2.[20]Nonhydrogen
atoms were refined anisotropically, whereas hydrogen atoms
were located at the calculated positions and refined by the
riding mode. The perchlorate ion in compound 2 was disor-
dered in a 0.55:0.45 ratio, and the same disorder was
observed for the pyridine in compound 2.
6H); 13C NMR (300 MHz, CDCl3):
δ = 149.81,
δ = 135.19, δ = 130.68, δ = 125.52, δ = 123.33, δ = 91.49,
and δ = 88.20 (elemental analysis: exp. [calc.], C84.05%
[84.94%], N10.94% [11.01%], and H3.98% [3.93%]). MASS
(Z = 1 C27H16N3 = 382.1339)
3.3 | {[Cu(L)2(ClO4)]ÁCH3CN}n (2)
Compound (1) (110.0 mg, 0.34 mmol) was dissolved in
30 mL of acetonitrile and 160 mg (0.43 mmol) of ligand L
was then added. The resulting solution was placed in a
sealed tube under a nitrogen atmosphere. The reactor was
then heated at 130ꢀC for 3 days and then allowed to cool to
room temperature at a rate of 13ꢀC/hr, orange color crystals
suitable for X-ray analysis were obtained. Yield 3.7%. IR
spectrum (KBr cm−1): 3,413(m), 3,062(m), 2,217(m), 1,944
(w), 1,603(s), 1,536(s), 1,489(s), 1,410(s), 1,322(m), 1,214
(s), 1,098(s), 1,058(s), 1,008(m), 987(m), 966(m), 879(s),
819(s), 747(w), 678(s), 622(s), and 599(w). (Elemental anal-
ysis: exp. [Calc.], C 69.58% [69.50%], N 10.00% [10.14%],
and H 3.38% [3.41%]).
4 | CONCLUSIONS
Based on the experimental conditions, we speculate that a
high ratio of metal ions can cause the complexes tend to
form low coordinating frameworks. This is an intuitive con-
clusion in which we assume that a high metal ion ratio
would increase the number of collisions between metal ions,
and this, in turn, would decrease the number of reactions
between ligands and metal ions. The tris(4-pyridylethynyl)
benzene ligand described here can be used to produce MOFs
with different structures by using different ratios of reac-
tants. The π–π stacking that can occur in such a special con-
jugate system as this can be quite diverse. In addition to the
common benzene ring and pyridine, some other π–π forces
such as ethyne–Py or ethyne–Bz can also be involved.
Armed with these π–π interactions, such materials can form
interpenetrating planes and even lead to highly symmetrical
structures. It should be noted here that numerous reports
have appeared concerning the formation of general complex
and cage compounds using this ligand. Nevertheless, MOFs
purely prepared using this ligand (L) are unprecedented.
With the current work, we report two new MOF structures
formed by using this tris(4-pyridylethynyl)benzene ligand.
3.4 | [Cu(L)(ClO4)] 2CH3CN (3)
Compound (1) (1.50 g, 4.59 mmol) was dissolved in 30 mL
of acetonitrile. Ligand L 150 mg (0.41 mmol) was then
added. The solution was placed in a sealed tube under a
nitrogen atmosphere and then heated at 130ꢀC for 3 days.
The solution was then allowed to cool to room temperature
at a rate of 13ꢀC/hr. An amount of 50 mg of pale yellow
block-shaped crystals was obtained. Yield 3%. IR spectrum
(KBr cm−1): 3,414(s), 2,442(m), 2,218(s), 1,605(s), 1,537
(m), 1,492(s), 1,417(s), 1,291(w), 1,213(s), 1,115(s), 1,086
(s), 1,019(s), 968(s), 888(s), 826(s), 754(w), 682(s), and 626
(s) 547(s). (Elemental analysis: exp. [calc.], C 57.23%
[57.22%], N 12.91% [9.94%], and H 3.96% [3.35%]).
3.5 | Physical property measurements
NMR spectra were recorded using a Bruker AV-300 spec-
trometer. Infrared spectra were recorded using KBr pellets

8
YANG ET AL.
[8] H. Li, M. Eddaoudi, M. O'Keeffe, O. M. Yaghi, Nature 1999,
402, 276.
Compounds 2 and 3, each has its own special framework.
Compound 2 forms an octet with a (4,2) node network and
compound 3 forms a hexagonal structure with a (3,3) node
network. Given these findings, we conclude that they will
stimulate the development of a new research branch and that
the findings will open up the gate to the formation of other
types of such complexes.
[9] H. L. Anderson, C. J. Walter, A. Vidal-Ferran, R. A. Hay,
P.A.Lowden, J.K.M.Sanders,J. Chem. Soc, Perk. 1995,1(18), 2275.
[10] (a) M. Schweiger, T. Yamamoto, P. J. Stang, D. Bläser, R. Boese,
J. Org. Chem. 2005, 70(12), 4861. (b) K. Ghosh, J. Hu,
H. S. White, P. J. Stang, J. Am. Chem. Soc. 2009, 131(19), 6695.
(c) H.-B. Yang, K. Ghosh, N. Das, P. J. Stang, Org. Lett. 2006, 8
(18), 3991. (d) H.-B. Yang, K. Ghosh, B. H. Northrop,
P. J. Stang, Org. Lett. 2007, 9(8), 1561.
ACKNOWLEDGMENTS
[11] S. Winter, E. Weber, L. Eriksson, I. Csöregh, New J. Chem. 2006,
30(12), 1808.
This work was supported by the Ministry of Science and
Technology of Taiwan (MOST106-2113-M-030-008).
Supporting information Compound (2) and compound
(3) have been deposited with CambridgeCrystallographic
Data Centre,CCDC number 1871203 and 1871204. The
ligand LTGA(Figure 1S) have been attached.Powder X-ray
(Figure 2S), NMR H spectra(Figure 3S),ORTEPs, ESI-
MASS(5S) for ligand L(Figure 4S). Furthermore, Crystal
data(table 1S to 10S) about compound(2)and compound
(3) was specificallyrecorded.
[12] S. Neogi, G. Schnakenburg, Y. Lorenz, M. Engeser,
M. Schmittel, Inorg. Chem. 2012, 51(20), 10832.
[13] (a) A. Ciesielski, W. R. Szabelski, A. Cadeddu, T. R. Cook,
P. J. Stang, P. Samorì, J. Am. Chem. Soc. 2013, 135(18), 6942.
(b) D. Ecija, S. Vijayaraghavan, W. Auwärter, S. Joshi,
K. Seufert, C. Aurisicchio, D. Bonifazi, J. V. Barth, ACS Nano
2012, 6(5), 4258. (c) D. Trawny, P. Schlexer, K. Steenbergen,
J. P. Rabe, B. Paulus, H.-U. Reissig, ChemPhysChem 2015, 16
(5), 949. (d) S. Vijayaraghavan, W. D. Ecija, S. Auwärter,
K. Joshi, M. Seufert, D. Drach, P. Nieckarz, C. Szabelski,
D. Aurisicchio, J. V. B. Bonifazi, Chem.-Eur. J. 2013, 19(42),
14143. (e) Q.-N. Zheng, X.-H. Liu, T. Chen, H.-J. Yan, T. Cook,
D. Wang, P. J. Stang, L.-J. Wan, J. Am. Chem. Soc. 2015, 137
(19), 6128.
ORCID
[14] N. Kobayashi, M. Kijima, J. Mater. Chem. 2008, 18(9), 1037.
[15] T. R. Cook, Y.-R. Zheng, P. J. Stang, Chem. Rev. 2013, 113
(1), 734.
En-Che Yang https://orcid.org/0000-0002-2987-2131
REFERENCES
[16] V. A. Blatov, A. P. Shevchenko, D. M. Proserpio, Cryst. Growth
Des. 2014, 14(7), 3576.
[17] (a) E. G. Hohenstein, C. D. Sherrill, J. Phys. Chem. A 2009, 113
(5), 878. (b) B. K. Mishra, N. Sathyamurthy, J. Phys. Chem. A
2005, 109(1), 6.
[18] G. M. Sheldrick, SADABS: Version 2.03, University of Göttingen,
Göttingen, Lower Saxony, Germany, 2002.
[19] G. M. Sheldrick, Acta Crystallogr. A 1990, 46, 467.
[20] G. M. Sheldrick, SHELXL-97, University of Göttingen, Göttingen,
Lower Saxony, Germany, 1997.
[1] (a) O. K. Farha, A. Özgür Yazaydın, I. Eryazici, C. D. Malliakas,
B. G. Hauser, M. G. Kanatzidis, S. T. Nguyen, R. Q. Snurr,
J. T. Hupp, Nat. Chem. 2010, 2, 944. (b) J. A. Mason,
M. Veenstra, J. R. Long, Chem. Sci. 2014, 5(1), 32.
[2] (a) B. Chen, C. Liang, J. Yang, D. S. Contreras, Y. L. Clancy,
E. B. Lobkovsky, O. M. Yaghi, S. Dai, Angew. Chem. Int. Ed.
2006, 45(9), 1390. (b) Z.-Y. Gu, C.-X. Yang, N. Chang, X.-
P. Yan, Acc. Chem. Res. 2012, 45(5), 734.
[3] (a) J. Lee, O. K. Farha, J. Roberts, K. A. Scheidt, S. T. Nguyen,
J. T. Hupp, Chem. Soc. Rev. 2009, 38(5), 1450. (b) C.-D. Wu,
A. Hu, L. Zhang, W. Lin, J. Am. Chem. Soc. 2005, 127(25),
8940. (c) M. Yoon, R. Srirambalaji, K. Kim, Chem. Rev. 2012,
112(2), 1196.
[4] (a) Z. Hu, B. Deibert, J. Li, Chem. Soc. Rev. 2014, 43(16), 5815.
(b) L. E. Kreno, K. Leong, O. K. Farha, M. Allendorf, R. P. Van
Duyne, J. T. Hupp, Chem. Rev. 2012, 112(2), 1105.
SUPPORTING INFORMATION
Additional supporting information may be found online in
the Supporting Information section at the end of this article.
How to cite this article: Yang E-C, Wu C-M,
Pan P-J, Lee G-H, Sheu H-S, Chang C-K. The
structures of MOFs prepared from 1,3,5-tris [4-
pyridylethynyl]-benzene and a copper(I) perchlorate
complex. J Chin Chem Soc. 2019;1–8. https://doi.org/
10.1002/jccs.201900022
[5] B. Gole, A. K. Bar, P. S. Mukherjee, Chem. Commun. 2011, 47,
12137.
[6] (a) B. Chen, S. Xiang, G. Qian, Acc. Chem. Res. 2010, 43(8),
1115. (b) U. Mueller, M. Schubert, F. Teich, H. Puetter,
K. Schierle-Arndt, J. Pastré, J. Mater. Chem. 2006, 16
(7), 626.
[7] S. S. Y. Chui, S. M. F. Lo, J. P. H. Charmant, A. G. Orpen,
I. D. Williams, Science 1999, 283(5405), 1148.