Static and dynamic coordination behaviours of copper(i) ions in hexa(2-pyridyl)benzene ligand systems

Article abstract of DOI:10.1039/c8dt01424h

Two hexaarylbenzenes having six pyridine substituents (L_H and L_M) were prepared and six corresponding coordination complexes with copper(i) chloride were synthesized. Monomeric complexes (1, 2a and 2b) and 1D coordination polymers (3

Full text of DOI:10.1039/c8dt01424h

View Article Online
View Journal
Dalton
Transactions
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: H. Kwon and E.
Lee, Dalton Trans., 2018, DOI: 10.1039/C8DT01424H.
Volume 45 Number
1
7
January 2016 Pages 1–398
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Dalton
Transactions
An international journal of inorganic chemistry
www.rsc.org/dalton
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1477-9226
PAPER
Joseph T. Hupp, Omar K. Farha et al.
Efficient extraction of sulfate from water using
framework
a Zr-metal–organic
rsc.li/dalton

Page 1 of 8
Plea sDe a dl t oo nn oT tr aa nd sj ua cs tt i om nasrgins
View Article Online
DOI: 10.1039/C8DT01424H
Journal Name
ARTICLE
Static and dynamic coordination behaviours of copper(I) ions in
hexa(2-pyridyl)benzene ligand systems
a
abc
Hyunchul Kwon, Eunsung Lee *
Received 00th January 20xx,
Accepted 00th January 20xx
H M
Two hexaarylbenzenes having six pyridine substituents (L and L ) were prepared and six corresponding coordination
DOI: 10.1039/x0xx00000x
complexes with copper(I) chloride were synthesized. The monomeric complexes (1, 2a and 2b) and 1D coordination
polymers (3, 4 and 5) were synthesized via the judicious concentration control of copper(I) ions and characterized fully
including X-ray crystal analysis. The binding modes of the ligands to copper(I) ions in the coordination polymers were
dependent on steric effects and solvents to determine the morphology of the coordination polymers. More interestingly,
dynamic behaviours of the monomeric complexes (1, 2a and 2b) in the solution phase were studied to show potential
www.rsc.org/
applications
of
molecular
machines
with
fluxional
motions.
interest because they have rotatable peripheral aromatic units
to the central benzene ring. Thus, the propeller-shaped and
Introduction
radially
π extended HABs are applicable to liquid crystalline
materials, building blocks in supramolecular chemistry,
Multi-metallic systems have been of great interest because of
the synergistic effect on various catalytic reactions to lower
activation energy. To envision such multi-metallic complexes, a
variety of novel ligands have been developed with multiple P,
2
7-31
molecular receptors and metal sensors.
interested in hexa(2-pyridyl)benzene derivatives (LH and LM
that possess six 2-pyridyl groups attached to a central benzene
We were
)
2
-8
O, N and C donors in the ligand. Among them, pyridine
based multi-ligand systems have been intensively studied
because of the strong and rigid sigma-donor properties that
3
2,33
ring.
With these ligands, we successfully synthesized
various monomeric and polymeric copper(I) coordination
complexes by utilizing their diverse coordinating combinations
of six pyridine sites in the ligand. In addition, all structural
characterization of the coordination complexes was conducted
by X-ray single crystal analysis. More importantly, we have also
studied the conformation of the ligands and nuclearity of the
complexes with different equivalents of copper(I) chloride
including the interesting solution behaviours of mono- and
dinuclear copper(I) complexes and the luminescence
properties of three different 1D coordination polymers with
tetranuclear copper(I) chloride cluster.
9
-12
secure the stability of metal complexes.
In particular,
polypyridyl ligands with a high symmetry appear to be
promising for achieving their intriguing topology and versatile
1
3,14
coordination ability.
polypyridyl ligands that can form unique multi-metallic
complexes are described in Figure 1. The ligands (tppz:
(tptz: 2,4,6-tris(2-
have been extensively studied as
Representative examples of
A
1
5-18
2
,3,5,6-tetrakis(2-pyridyl)pyrazine)
and B
1
9-21
pyridyl)-1,3,5-triazine)
multi-metallic systems with various transition metals, showing
ligand-assisted energy transfer and fluxional behaviours. The
ligand
C (hexa(2-pyridyl)[3]radialene) has been studied as
N
N
coordination complexes with silver(I) salts to form hexapodal
2
N
N
N
N
N
N
2,23
N
N
prismatic structures and coordination polymers.
2
In
N
4,25
26
N
N
addition, the ligands (
D
1
and
D
2
) with extended pyridine
N
N
N
N
N
sites have been utilized as supramolecular building blocks for
constructing tetrahedron-, box- and octahedron-shaped
coordination cages.
A
B
C
N
Hexaarylbenzene (HAB) derivatives are of our particular
N
N
N
N
R
R
N
N
N
N
N
N
N
N
N
N
L
H
L
M
R
R =Me (D
1
),
O
2
(D )
Figure
pyridyl)benzene (
1
.
Examples of highly symmetrical polypyridines including hexa(2-
) and hexa(2-(5-methylpyridyl)benzene) ( ).
L
H
L
M
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 2 of 8
View Article Online
DOI: 10.1039/C8DT01424H
ARTICLE
Journal Name
Table 1. Selected Crystal Data and Refinement Detail.
1
‧2(CH
3
CN)
Cu
2a
2b‧CH
3
CN
Cu
3
4
5
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
a / Å
C
48
H
45Cl
1
1
N
9
C
20
H
15Cl
1
Cu
1
N
4
25
C H
24Cl
1
1
N
5
C
18
H
12Cl
2
Cu
2
N
3
C
46
H
42Cl
4
Cu
4
N
8
25 2 2 3 2
C H26Cl Cu N O
846.92
100
410.35
100
246.74
100
468.29
298
1102.83
100
582.47
100
monoclinic
C2/c
monoclinic
P2 /n
Triclinic
P-1
orthorhombic
Pnnm
monoclinic
P2 /c
monoclinic
P2 /c
1
1
1
23.704(5)
14.101(3)
27.437(6)
90
10.933(2)
13.690(3)
11.946(2)
90
8.9830(18)
12.124(2)
12.321(3)
106.64(3)
94.63(3)
108.42(3)
1198.0(5)
2
10.0389(3)
11.3316(3)
16.6903(4)
90
11.435(4)
24.695(9)
17.511(6)
90
9.4650(19)
14.559(3)
17.362(4)
90
b / Å
c / Å
α
β
γ
/ °
/ °
/ °
108.20(3)
90
95.49(3)
90
90
108.053(11)
90
95.38(3)
90
90
3
Volume / Å
Z
8712(3)
8
1779.8(6)
4
1898.64(9)
4
4701(3)
4
2382.0(8)
4
Radiation
synchrotron
λ = 0.71073)
synchrotron
MoKα
CuKα
MoKα
synchrotron
(λ = 0.700)
0.0350
(
(λ = 0.71073)
0.0492
(λ = 0.71073)
0.0347
(λ = 1.54178)
0.0709
0.1149
(λ = 0.71073)
0.0505
R
1
[ I ≥ 2δ (Ι) ]
0.0859
0.2237
wR [ I ≥ 2δ (Ι) ]
0.1011
0.1138
0.1359
0.1086
2
Experimental Section
Synthesis of hexa(2-pyridyl)benzene (L
Under N atmosphere, 2-phenylpyridine (0.16 g, 1.0 mmol),
)RuCl (0.025 g, 0.050 mmol), triphenylphosphine
0.053 g, 0.20 mmol), and potassium carbonate (1.66 g, 12.0
H
).
that contains 5 mL of N-methyl-2-pyrrolidone (NMP). The
solution was stirred and heated to 140 °C. At this temperature,
the solution of NMP (3 mL) with 2-bromo-5-methylpyridine
2
6
[
(η
-C
6
H
6
2 2
]
(
2.38 g, 14 mmol) was added dropwise by a syringe pump over
4 h, and further stirred for 24 h at the same temperature. The
(
2
mmol) were added as one pot in a flask that contains 5 mL of
N-methyl-2-pyrolidone (NMP). The solution was stirred and
heated to 140 °C. At this temperature, 2-bromopyridine (1.58
g, 10.0 mmol) was added dropwise by a syringe pump over 24
hours, and further stirred for 24 hours at the same
temperature. The organic portion of the mixture was extracted
with chloroform several times after addition of water to the
reaction mixture to remove NMP. The extracted solution was
dried over anhydrous sodium sulphate and all volatiles of the
solution were removed in vacuo. The desired product was
purified from the residue by silica gel chromatography
organic portion of the mixture was extracted with chloroform
several times after addition of water to the mixture to remove
NMP. The extracted solution was dried over anhydrous sodium
sulfate and all the volatiles of the solution were removed in
vacuo. The residue was purified by silica gel chromatography
3
(acetone : methanol : Et N = 20 : 2 : 1). A white solid was
recrystallized in THF and dried for further purification. Hexa(2-
1
(
5-methylpyridyl))benzene (0.139 g, 15.8% yield). H NMR (500
MHz, CD CN): 7.92 (s, 6H), 7.08 (dd, J = 7.8, 1.8 Hz, 6H), 6.82
d, J = 7.8, 6H) ppm. C NMR (125 MHz, CD
3
δ
1
3
(
3
CN)
41.1, 135.7, 130.9, 127.0, 18.0 ppm. HR-MS : [M + H] (m/z) =
25.3084; calcd. value for C42 = 625.3079.
δ 156.6, 149.0,
1
6
3
(acetone : methanol : Et N = 20 : 2 : 1). A white solid was
36 6
H N
recrystallized in THF and dried for further purification. Hexa(2-
1
pyridyl)benzene (0.077 g, 14.2% yield). H NMR (500 MHz,
Synthesis of [L
atmosphere, hexa(2-(5-methylpyridyl))benzene (10.0
158.2, 147.8, 140.2, mg, 0.016 mmol, 1.0 equiv) and CuCl (1.6 mg, 0.016 mmol, 1.0
34.3, 126.7, 120.7 ppm. HR-MS : [M + H] (m/z) = 541.2139; equiv) was dissolved in acetonitrile (1 mL) at room
M 3 3 3
CuCl(CH CN)]‧2(CH CN) (1‧2(CH CN)).
CD
3
CN):
δ 8.06 (ddd, J = 5.0, 1.8, 1.0 Hz, 6H), 7.25 (td, J = 7.8,
1
6
1
.8 Hz, 6H), 6.94 (d, J = 7.8, 6H), 6.84 (ddd, J = 7.2, 4.8, 1.0 Hz, Under N
2
1
3
H) ppm. C NMR (125 MHz, CD3CN)
δ
calcd. value for C36
H
25
N
6
= 541.2141.
temperature. Bright yellow block formed in a week. After 2
weeks, the yellow solution was decanted and the yellow
crystalline solid was washed with THF (2 x 1 mL) and dried. The
product was isolated as a bright yellow colored crystalline solid
Synthesis of hexa(2-(5-methylpyridyl))benzene (L
Under N atmosphere, 5-methyl-2-phenylpyridine (0.239 g, 1.4
mmol), [(
M
).
2
1
(6.2 mg, 46% yield). The yellow crystals were suitable for
6
η
-C
6
H
6
)RuCl
2
]
2
(0.100 g, 0.2 mmol), tri-
1
single crystal X-ray diffraction (XRD) analysis. H NMR (500
MHz, CD CN): 8.03 (s, 6H), 7.13 (d, J = 7.6, 6H), 6.88 (d, J =
.6, 6H), 2.10 (s, 18H) ppm.
phenylphosphine (0.210 g, 0.8 mmol), and potassium car-
bonate (3.32 g, 24.0 mmol) were added as one pot in a flask
3
δ
7
2
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 8
Plea sDe a dl t oo nn oT tr aa nd sj ua cs tt i om nasrgins
View Article Online
DOI: 10.1039/C8DT01424H
Journal Name
ARTICLE
M
Scheme 1. Synthesis of copper(I) complexes. (a) L , 1 equiv. of CuCl, CH
3
CN, rt, 14 days, 46%, (b) L
H
3 M 3
, 2 equiv. of CuCl, CH CN, rt, 2hrs, 88%, (c) L , 2 equiv. of CuCl, CH CN, rt, 14
days, 40%, (d) L
H
, 10 equiv. of CuCl, CH
3 M 3 M
CN, rt, 2hrs, 95%, (e) L , 10 equiv. of CuCl, CH CN, rt, 14 days, 73%, (f) L , 4equiv. of CuCl, CH
3
CN, rt, 14days, 91%.
1
3
C NMR (125 MHz, CD
31.7, 127.2, 18.0 ppm. Anal. Calcd for C44
9.10; H, 5.14; N, 12.82. Found: C, 69.10; H, 5.11; N, 13.02.
3
CN):
δ
155.8, 149.0, 141.0, 136.3, Under N
2
atmosphere, hexa(2-pyridyl)benzene (10.0 mg, 0.018
1
6
H39Cl
1
Cu
1
N
7
: C, mmol, 1.0 equiv) was added in the solution of CuCl (18.0 mg,
0.18 mmol, 10.0 equiv) in acetonitrile (1 mL) at room
temperature. Yellow rod-shaped crystals were formed in 2
hours. After 2 days, the yellow solution was decanted and the
yellow crystalline solid was washed with THF (2 x 1 mL) and
Synthesis of L
H 2 2 3 2
Cu Cl (CH CN) (2a).
Under N atmosphere hexa(2-pyridyl)benzene (30.0 mg, 0.056
2
dried. The product was isolated as an orange colored
crystalline solid (16.4 mg, 95% yield). Obtained yellow
crystals were suitable for single crystal XRD analysis. Anal.
Calcd for C18 Cu : C, 46.17; H, 2.58; N, 8.97. Found: C,
6.23; H, 2.51; N, 9.26.
mmol, 1.0 equiv) and CuCl (10.8 mg, 0.112 mmol, 2.0 equiv)
was dissolved in acetonitrile (1 mL) at room temperature.
Bright yellow block crystals were formed immediately. After 2
h, the yellow so-lution was decanted and the crystalline solid
was washed with THF (2 x 1 mL) and dried. The product was
isolated as a yellow colored crystalline solid 2a (39.8 mg, 88%
yield). The yellow crystals were suitable for single crystal XRD
3
H12Cl
2
2 3
N
4
Synthesis of [L
Under N atmosphere, hexa(2-(5-methylpyridyl))benzene (15.0
mg, 0.024 mmol, 1.0 equiv) and CuCl (24.0 mg, 0.24 mmol,
0.0 equiv) was dissolved in acetonitrile (1 mL) at room
M 4 4 3 n 3 n
Cu Cl (CH CN)] ∙(CH CN) (4).
2
analysis. 1H NMR (500 MHz, CD3CN, 323K): δ 8.26 (s, 6H), 7.36
t, J = 7.3, 6H), 7.07 (d, J = 7.6, 6H), 6.97 (t, J = 7.6, 6H) ppm.
(
1
Anal. Calcd for C40H30Cl2Cu2N8: C, 58.54; H, 3.67; N, 13.65.
Found: C, 58.41; H, 3.56; N, 13.57.
temperature. Orange needle crystals were formed in a week.
After 2 weeks, the yellow solution was decanted and the
orange crystalline solid was washed with THF (2 x 1 mL) and
Synthesis of [L
M 2 2 3 2 3 3
Cu Cl (CH CN) ]‧(CH CN) (2b‧CH CN).
dried. The product was isolated as an orange crystalline solid
19.4 mg, 73.3% yield). Obtained yellow crystals were suitable
for single crystal XRD. analysis. Anal. Calcd for C46 Cu
C, 50.10; H, 3.84; N, 10.16. Found: C, 49.70; H, 3.83; N, 10.11.
4
Under N atmosphere, hexa(2-(5-methylpyridyl))benzene (10.0
2
(
mg, 0.016 mmol, 1.0 equiv) and CuCl (3.2 mg, 0.032 mmol, 2.0
equiv) was dissolved in acetonitrile (1 mL) at room tempera-
ture. Yellow block crystals were formed in a week. After 2
weeks, the yellow solution was decanted and the yellow
crystalline solid was washed with THF (2 x 1 mL) and dried. The
product was isolated as a yellow colored crystalline solid 2b
H42Cl
4
4 8
N :
Synthesis of [L
M 4 4 n n
Cu Cl ] ‧(THF) (5).
Under N atmosphere, hexa(2-(5-methylpyridyl))benzene (10.0
2
mg, 0.016 mmol, 1.0 equiv) and CuCl (6.4 mg, 0.064 mmol, 4.0
equiv) was dissolved in acetonitrile (1 mL) and in the vapor
diffusion of THF into acetonitrile solution at the room
temperature. Red block formed in 2 days. After a week, yellow
solution was decanted and Red crystalline solid was washed
with THF (2 x 1 mL) and dried. The product was isolated as a
(5.9 mg, 40% yield). Obtained yellow crystals were suitable for
1
single crystal XRD analysis. H NMR (500 MHz, CD
s, 6H), 7.15 (d, J = 7.8, 6H), 6.89 (s, 6H). 2.11 (s, 18H) ppm.
NMR (125 MHz, CD CN): 155.2, 148.9, 140.9, 136.7, 132.3,
27.2, 18.0 ppm. Anal. Calcd for C48 Cu : C, 60.95; H,
.80; N, 13.33. Found: C, 60.11; H, 4.72; N, 13.36.
3
CN): δ 8.08
1
3
(
C
3
δ
1
4
H45Cl
2
2 9
N
red crystalline solid
crystals were suitable for single crystal XRD analysis. Anal.
Calcd for C100 Cu : C, 51.55; H, 4.50; N, 7.21.
Found: C, 51.43; H, 4.41; N, 7.60.
5 (16.9 mg, 90.9% yield). Obtained yellow
H 4 4 n
Synthesis of [L Cu Cl ] (3).
H104Cl
8
8 12 4
N O
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 4 of 8
View Article Online
DOI: 10.1039/C8DT01424H
ARTICLE
Journal Name
and to a chloride anion outward the arene center. The ligands
in complexes 2a and 2b have the same conformation,
functioning as a bis-bidentate ligand with copper(I) chloride.
Result and Discussions
Synthesis and Characterization.
The synthesis of
H M
L and L was carried out by one-pot
procedure. The dropwise addition of 2-bromopyridine to the
6
mixture of 2-phenylpyridine, [(
in NMP solution gives the
the solubility of the ligand, methyl groups were added in the 5-
position of pyridines. was synthesized by using 2-bromo-5-
methylpyridine and 5-methyl-2-phenylpyridine as starting
materials. The copper(I) complexes of 2a and ) and
and ) were prepared by combining the ligand with
η
-C
6 6 2 2 3 2 3
H )RuCl ] , PPh and K CO
L
H
in affordable yield. To improve
L
M
L
H
(
3
M
L (1,
2b
,
4
5
different equivalents of copper(I) chloride as described in the
experimental section. The addition of one equivalent of
copper(I) chloride to the acetonitrile solution of
and 2a crystals. Isolation of the complex with one equivalent
of copper(I) chloride ( ) was achieved by using . The
addition of two equivalents of copper(I) chloride in the
acetonitrile solution of and the solution of resulted in the
H H
L affords L
1
L
M
L
H
L
M
formation of yellow crystalline solid 2a and 2b, respectively.
The addition of more than 4 equivalents of copper(I) chloride
in the acetonitrile solution of
L
H
and the solution of
and , respectively.
was obtained as a yellow crystalline solid while
was obtained as an orange crystal. The
was obtained as a red crystalline solid
M
L induced
the formation of coordination polymers,
3
4
The complex
the complex
3
4
coordination polymer
5
by vapor diffusion of THF into an acetonitrile solution of
with 4 equivalents of copper(I) chloride.
L
M
Due to the solubility issue of hexa(2-pyridyl)benzene, the
copper(I) complexes containing were formed immediately
while the slow formation of the copper(I) complexes with
was observed (~ a week). The color of the complexes 2a
and turned to green after being exposed to air for one day as
L
H
L
M
1,
, 2b
3
M 3 3 3
Figure 2. Molecular structures of the [L CuCl(CH CN)]2(CH CN) 1∙2(CH CN) (a) and
a sign of oxidative decomposition in the solid state while the [L Cu Cl (CH CN) ]2(CH CN) 2b∙CH CN (b). Ellipsoids are shown at the 25% and 50%
M
2
2
3
2
3
3
color of the complexes
4
and
5
stayed the same, even after 2 probability levels for 1∙2(CH
3 3
CN) and 2b∙CH CN, respectively. Hydrogen atoms and
acetonitrile molecules in the lattice are omitted for clarity.
days, which indicates their oxidative stability.
1
The H NMR data of 1, 2a and 2b in CD CN show the same
3
Two distorted tetrahedral copper(I) centers have the same
pattern as the signals from the free ligand, even though the
overall chemical shifts of each complex moved downfield
compared to the ones of the free ligand. The X-ray structures
composition as one of the copper center in complex
1 with the
bite angles of 89.92 (13)° (2a) and 89.81 (8)° (2b). Two copper
centers are located on the opposite sides of the ring and the
remaining two pyridine rings are not involved in the
of
1, 2a, and 2b showed that the six pyridine rings are
1
nonequivalent, but the H NMR data do not distinguish the six
pyridine units, presumably because of the fast ligand exchange
in the copper(I) ions on the NMR time scale.
coordination of copper ions. In
1
, the C≡N triple bond in
acetonitrile, which binds on the copper atom, is inclined about
1
3
1
1° toward the central arene compared to its original direction
The C NMR spectra of 2a cannot be obtained due to low
(
∠Cu(1)–N(5)–C(29) = 168.9 (3)°). The C≡N triple bond also
solubility.
leans to the one side of the ring. This indicates that there is a
orbital interaction between the C≡N bond and the central
phenyl ring. On the other hand, the angle of Cu(1)–N(4)–C(9)
Cu(1)–N(3)–C(15)) is 176.6 (2)° (175.6 (8)°) in 2b 2a). The
acetonitrile molecules in 2b 2a) placed straight toward the
π-π
Solid-State Structures of Copper Complexes of L
Complex has only one copper(I) ion in the ligand. The two
pyridine units in the ligand chelate a single copper(I) ion with a
typical bite angle of a distorted tetrahedral geometry ( N(1)–
H M
and L .
1
(
(
(
∠
center of the central phenyl ring indicate that there is no
interaction between the C≡N bond and the phenyl ring (Figure
S26 and S27). This difference may originate from the longer
Cu(1)–N(4) = 87.91 (11)°) to form a rigid mononuclear
metallacycle that contains seven members. One acetonitrile
molecule binds to the copper ion inward to the central arene
4
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 8
Plea sDe a dl t oo nn oT tr aa nd sj ua cs tt i om nasrgins
View Article Online
DOI: 10.1039/C8DT01424H
Journal Name
ARTICLE
distance between the central arene and C≡N triple bond in 2b
2a) than the distance in
, as two C≡N triple bonds on the
both
(
1
Figure 3. Molecular structure of the [L
H
Cu
4
Cl
4
]
n
3 ((a) monomeric unit and (d) polymer), [L
M
Cu
4
Cl
4
(CH
3
CN)]
n
∙(CH
3
CN)
n
M 4 4 n n
4 ((b) monomeric unit and (e) polymer), and [L Cu Cl ] ∙(THF)
5
((c) monomeric unit and (f) polymer). Ellipsoids are shown at the 25%, 25%, and 50% probability levels for 3, 4, and 5, respectively. Hydrogen atoms and lattice solvent molecules
are
omitted
for
clarity.
sides of the arene ring may disperse the interaction between (5) Å). One chloride anion on the copper connects each
the arene and the C≡N bonds.
monomeric complex to expand the unit to the 1D coordination
polymer. The vertical distance between each monomer is
Solid-State Structures of the 1D Copper(I) Coordination Polymers
6.806 Å. The structure of the Cu
in Figure 4b. The dis-tances between the copper atoms in
complex correspond to 2.728 (8) Å (Cu(2)–Cu(1)), 2.905 (5) Å
Cu(2)–Cu(3)), and 2.808 (2) Å (Cu(3)–Cu(4)), indicating that all
4 4
Cl metal cluster in 4 is shown
of L
The structures of the monomeric units and polymeric
structures of the complexes and are shown in Figure 3
In the complex , six pyridine binding sites in are involved in
H M
and L .
4
(
3,
4
5
.
four copper(I) ions in the cluster stand in a line, as they
interact with each other.
3
L
H
the coordination of two sets of copper(I) dimers. Two copper(I)
dimers are located on the opposite sides of the central phenyl
ring and each dimer binds to the three pyridines. The pyridine
on the middle of the copper(I) dimer is perpendicular to the
attached arene units (Figure 3a). The distance between Cu(1)
and N(1) is 2.045 (5) Å while the distance between Cu(1) and
N(2) is 2.392(7) Å, which is longer than the typical Cu–N bond
distance. Each monomer is linked with tetranuclear copper(I)
clusters to form a 1D coordination polymer. The vertical
distance between each monomer was measured as 7.910 Å.
From comparing 3 and 4, it is evident that six methyl groups on
the ligand provide a steric effect that causes a dramatic change
in the formation of copper(I) chloride clusters on each
polymer. In
while does not show close packing due to the steric
hindrance of methyl groups (Figure S29 and S30). Thus, in
3, each coordination polymer is closely packed
4
4
,
the solvent molecules were diffused into the crystal lattice as
well as the metal ion centers during the complexation and
crystallization processes since methyl groups interrupt the
close packing of the 1D coordination polymers in
a void volume in the crystal lattice.
4 and create
The Cu
Figure 4a). The bond length of the bimetallic coppers in
complex is 2.657 (5) Å (Cu(1)–Cu(1’)).
In the complex , the ligand shows almost the same
configuration as the one of the ligand in . Each binding site in
the ligand is coordinated by two sets of copper(I) dimers.
4 4 4 2
Cl cluster of 3 is constituted by a planar Cu Cl ring
(
Despite having the same component with the same
stoichiometry as the complex , complex has an entirely
3
4
5
4
different copper chloride cluster and connectivity. The ligand
binds with four copper atoms. Two copper atoms (Cu(1) and
Cu(2’)) on the same side of the ligand are bridged by a chloride
anion located 3.369 Å away from each other, which does not
3
L
M
Two copper(I) dimers are located on the opposite sides of the
ring. The distance between Cu(2) and N(3) (2.081 (3) Å) is
shorter than the distance between Cu(1) and N(3) (2.832 (5)
Å). Likewise, the distances between Cu(4) and N(7) (2.278 (3)
Å) is shorter than the distance between Cu(3) and N(7) (2.719
3
4
support copper-copper interactions. On each side, one
copper ion (Cu(1)) coordinates with two pyridines while the
other copper ion (Cu(2’) coordinates with the remaining
pyridine. The copper-nitrogen bond distances range from
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 6 of 8
View Article Online
DOI: 10.1039/C8DT01424H
ARTICLE
Journal Name
2.024 (3) (Cu(2)–N(3)) to 2.102 (1) Å (Cu(1)–N(1)), which are in one set of 2-pyridyl chemical shift. This suggests that all six
accordance within the range of the common copper-nitrogen pyridines in the ligand attribute equally to the dynamic
bond distance. Each monomer is linked with the stair-step motions of copper(I) ligand complexes. As the temperature
3
5
4 4
Cu Cl cluster to form a coordination polymer. In addition, decreases, the signals became broad due to the comparable
the distance between the
rate of the dynamic motions on the NMR time scale. The
coalescence of the signal was observed at 273K. A decrease in
temperature led to the separation of the signals from each
proton due to the slower exchange process. At 223K, all proton
signals become narrow and split to each peak.
Complex 2a has four coordinating pyridine rings and two
free pyridine rings in the ligand so that the proton peaks
should be split to a ratio of 2:1 if there is no accidental
degeneracy of each proton peak. Indeed, integration values
obtained from all signals at 223K were measured at a
2
:1:2:1:2:1:2:1 ratio in accordance with the structure attained
1
by X-ray crystal analysis (Figure 2). In H two-dimensional
exchange spectroscopy (2D EXSY) spectra of 2a at 233K, the
interconversions between the proton signals of a free pyridine
and a bound pyridine to copper were detected (Figure S14).
1
The signals of the phenyl resonance region in H 2D EXSY
showed cross peaks between the hydrogen pairs of the
coordinating pyridines and the free pyridines in 2a. These cross
peaks strongly indicated an exchange process between the
non-coordinating pyridines and the pyridines coordinating
with copper(I) ion in 2a, either via an intra- or intermolecular
1
pathway. In addition, H NMR spectra of 2a solution at 223K
showed other signals at a range of 8.3 to 8.4 ppm. In 2D EXSY
spectra of 2a solution, there are other cross peaks between
this signals and the signals of 2a. This cross peak shows that
Figure 4. Molecular structure of the Cu
4
Cl
4
N
6
clusters in (a) [L
H 4 4 n
Cu Cl ] 3, (b)
[
M
L Cu
4
Cl
4 3
(CH CN)]
n
∙(CH
3
CN)
n
M
4, and (c) [L Cu
4
Cl
4
]
n
∙(THF) 5.
n
there are intermediates involved in the dynamic process of 2a
.
copper atoms in complex
5 is 2.781 (1) Å (Cu(1) and Cu(2)) for
The other signals from the intermediates cannot be
bimetallic coppers in the cluster. The vertical distance between
each monomer is 7.914 Å.
distinguished due to an intensive overlap. The activation
‡
parameters,
e.u.,
∆H = 16.47 ± 0.02 kcal/mol,
∆
S‡ = 13.40 ± 0.16
The two coordination polymers of
and , show the solvent effect in the formation of the
copper(I) complex. Crystals of were grown from a solution
M
L described above, 4
5
4
containing acetonitrile predominantly. In the crystal structure,
acetonitrile was found to have occupied the one site of the
copper(I) chloride cluster and free acetonitriles were included
uniformly in the void of the polymer (Figure S30). Meanwhile,
the crystal structure of
5 revealed that no solvent molecules
are coordinated with the copper(I) centers and only THF
molecules were found in the lattice of the crystals. This
difference between
4 and 5 implies that some amount of THF
in the acetonitrile solution carried out a key role in controlling
the moiety of the coordination polymers (Figure S31).
Solution Behaviours of 1, 2a and 2b.
1
In the H NMR spectra, complexes
1,
2a and 2b show the
temperature dependence that indicates dynamic exchange
processes occurring in the solutions of 2a and 2b. To study
H variable temperature (VT)
-acetonitrile were conducted (for analysis of
NMR spectra of and 2b, see Figure S16 S17, and S18).
Figure 5 shows the H VT-NMR spectra at the range of 323K to
1,
1
this behaviour of complex 2a
,
NMR studies in d
3
1
the
H
1
,
1
1
2
23K. At 323K, H NMR spectra showed only four sets of peaks
at 8.27, 7.36, 7.07, and 6.97 ppm, respectively, indicating only
6
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 8
Plea sDe a dl t oo nn oT tr aa nd sj ua cs tt i om nasrgins
View Article Online
DOI: 10.1039/C8DT01424H
Journal Name
ARTICLE
that, although there are more than 2 equivalents of copper(I)
chloride in the solution the ligand binds with only two
1
equivalents of copper(I) ion in the solution. The 1D and 2D H
NMR spectra of 2a indicated that complex 2a mainly exists in
the solution with a substoichiometric amount of the other
unknown species as an intermediate of the dynamic process.
Luminescent Properties of 3, 4, and 5.
In the solid state at room temperature,
3, 4, and 5 exhibited
yellow-red luminescence upon the exposure of ultraviolet
excitation (
was 577 nm while the emission maximum of
624 nm) were redshifted relative to that of
λ
exc = 380 nm). The emission maximum (
λ
(612 nm) and
max) of
3
5
4
(
3
(
Figure S19). All
complexes contained at least one Cu–Cu bond shorter than the
van der Waals radii (2.80 Å), and thus implies cuprophilic
interaction (Figure S28). The luminescent behaviours of
and were attributed to the cluster centered excited states
along with a chloride to copper charge transfer and copper-
3, 4,
5
3
6
centered transition (d
of was five times higher than that of
than that of . Variations in the intensity and emission maxima
of , and result from their respective differences in the
→
s). The photoluminescence intensity
4
3
and 50 times higher
5
3
,
4
5
structure of Cu
environments.
4
Cl
4
clusters and the supramolecular
Conclusion
Six copper(I) complexes of hexa(2-pyridyl)benzene derivatives,
and were newly prepared and characterized by single
crystal X-ray diffraction. Compounds and 2a and 2b
contained and equivalents of copper(I) chloride,
respectively. Interesting solution behaviour of 2a and 2b
were studied by H VT-NMR and 2D EXSY, indicating a dynamic
motion occurring in the acetonitrile solutions of 2a and 2b
1
Figure 5. H VT-NMR spectra of 2a in d
3
-acetonitrile solvent
L
H
L
M,
1
2
(
)
1
2
1,
1
1
,
.
The addition of four equivalents of copper(I) chloride to the
ligand in different conditions affords three different
coordination polymers. In the 1-D coordination polymers,
3, 4,
and 5, every binding sites in the ligand are involved in
coordination with four copper(I) atoms. The addition of six
methyl groups on the ligand and changes of the solvent caused
a dramatic effect on the structure of copper(I) chloride
clusters. Due to different structures of the copper cluster, each
coordination polymer exhibited different luminescence
behaviour. We believe that the understanding on these
coordination behaviours of hexa(2-pyridyl)benzene systems
provide a new choice of the building block for the potential
application on supramolecular chemistry and molecular
machines.
Figure 6. Photoluminescence emission spectra of 3, 4, and 5 in the solid state at λexc
=
3
80 nm.
‡
∆
G = 13.36 ± 0.11 kcal/mol, and E
a
= 16.9 kcal/mol for the
exchange process of 2a were derived from the Eyring plot
Figure S19). The positive ∆ ‡
value indicates a dissociative
(
S
Conflicts of interest
1
0
mechanism which is viable for a d electronic configuration
with no ligand field stabilization. The addition of copper(I)
chloride to the solution of 2a produces a similar signals of 2a in
There are no conflicts to declare
1
the H NMR spectra at 233K while the solutionwith one
Acknowledgements
equivalent of copper(I) chloride shows different signals
compared with the signals of 2a (Figure S18). This indicates
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 8 of 8
View Article Online
DOI: 10.1039/C8DT01424H
ARTICLE
Journal Name
This work was supported by the Institute for Basic Science(IBS) 28 G. L. Ning, M. Munakata, L. P. Wu, M. Maekawa, Y. Suenaga,
T. Kuroda-Sowa and K. Sugimoto, Inorg. Chem. 1999, 38
668-5673.
9 A. Miyasaka, T. Amaya and T. Hirao, Chem. Eur. J. 2014, 20
615-1621.
,
[
IBSR007-D1]. The X-ray crystallography analysis with
5
synchrotron radiation was performed at the Pohang
Accelerator Laboratory (PLS-II BL2D SMC). We thank Ms.
2
,
1
Yoolim Ahn for assistance with PL experiments. We thank Prof. 30 V. Vij, V. Bhalla and M. Kumar, Chem. Rev. 2016, 116, 9565-
Jaheon Kim for helpful discussions.
9627.
3
1 H. Ube, R. Yamada, J. I. Ishida, H. Sato, H.; M. Shiro and M.
Shionoya, J. Am. Chem. Soc. 2017, 139, 16470-16473.
2 JP 2008222687A, 2008.
3 G. R. Newkome, N. B. Islam and J. M. Robinson, J. Org. Chem.
1975, 40, 3514-3518.
3
3
References
1
2
3
J. F. Berry and C. M. Thomas, Dalton Trans. 2017, 46, 5472-
473.
K. T. Horak, A. Velian, M. W. Day and T. Agapie, Chem.
Commun. 2014, 50, 4427-4429.
E. Y. Tsui, J. S. Kanady, M. W. Day and T. Agapie, Chem.
Comm. 2011, 47, 4189-4191.
E. Y. Tsui and T. Agapie, Polyhedron 2014, 84, 103-110.
G. N. Di Francesco, A. Gaillard, I. Ghiviriga, K. A. Abboud and
L. J. Murray, Inorg. Chem. 2014, 53, 4647-4654.
X. Jiang, J. C. Bollinger and D. Lee, J. Am. Chem. Soc. 2005,
5
34 P. K. Mehrotra and R. Hoffmann, Inorg. Chem. 1978, 17
2187-2189.
35 S. Q. Bai, L. Jiang, A. L. Tan, S. C. Yeo, D. J. Young, and T. S. A.
Hor, Inorg. Chem. Front. 2015, , 1011-1018.
36 P. C. Ford, E. Cariati, J. Bourassa, Chem. Rev. 1999, 99, 3625-
3648.
,
2
4
5
6
7
8
127, 15678-15679.
H. Ju, J. K. Clegg, K. M. Park, L. F. Lindoy and S. S. Lee, J. Am.
Chem. Soc. 2015, 137, 9535-9538.
S. Park, S. Y. Lee, K. M. Park, and S. S. Lee, Acc. Chem. Res.
2
012, 45, 391-403.
9
1
R. D. Hancock, Chem. Soc. Rev. 2013, 42, 1500-1524.
0 K. Yamamoto, J. Li, J. A. O. Garber, J. D. Rolfes, G. B.
Boursalian, J. C. Borghs, C. Genicot, J. Jacq, M. van Gastel, F.
Neese and T. Ritter, Nature 2018, 554, 511-514.
1 A. R. Mazzotti, M. G. Campbell, P. Tang, J. M. Murphy, and T.
Ritter, J. Am. Chem. Soc. 2013, 135, 14012-14015.
2 L. F. Szczepura, L. M. Witham and K. J. Takeuchi, Coord.
Chem. Rev. 1998, 174, 5-32.
3 S. Pandey, P. P. Das, A. K. Singh and R. Mukherjee, Dalton
Trans., 2011, 40, 10758-10768.
4 B. Rezaei Rad, D. Herrmann, C. Lescop and R. Wolf, Dalton
Trans. 2014, 43, 4247-4250.
1
1
1
1
1
1
1
1
1
5 H. Hadadzadeh, A. R. Rezvani, G. P. A. Yap and R. J. Crutchley,
Inorg. Chim. Acta 2005, 358, 1289-1292.
6 C. W. Padgett, W. T. Pennington and T. W. Hanks, Cryst.
Growth. Des. 2005, 5, 737-744.
7 S. Zhao, S. M. Arachchige, C. Slebodnick and K. J. Brewer,
Inorg. Chem. 2008, 47, 6144-6152.
8 J. Carranza, J. Sletten, C. Brennan, F. Lloret, L. Cano, and M.
Julve, Dalton Trans., 2004, 0, 3997-4005.
9 A. Baez-Castro, J. Baldenebro-Lopez, A. Cruz-Enriquez, H.
Hopfl, D. Glossman-Mitnik, V. Miranda-Soto, M. Parra-Hake,
E. Reynoso-Soto and J. J. Campos-Gaxiola, Inorg. Chim. Acta
2
017, 466, 486-496.
2
2
0 R. Wietzke, M. Mazzanti, J. M. Latour and J. Pecaut, Inorg.
Chem. 1999, 38, 3581-3585.
1 M. C. Aragoni, M. Arca, M. Crespo, F. A. Devillanova, M. B.
Hursthouse, S. L. Huth, F. Isaia, V. Lippolis and G. Verani,
Dalton Trans., 2009,
2 P. J. Steel and C. J. Sumby, Chem. Comm. 2002,
3 P. J. Steel, and C. J. Sumby, Inorg. Chem. Comm. 2002,
27.
0, 2510-2520.
2
2
0
, 322-323.
5
, 323-
3
2
2
2
2
4 S. Hiraoka, K. Harano, M. Shiro, and M. Shionoya, J. Am.
Chem. Soc. 2008, 130, 14368-14369.
5 S. Hiraoka, T. Nakamura, M. Shiro and M. Shionoya, J. Am.
Chem. Soc. 2010, 132, 13223-13225.
6 S. Hiraoka, Y. Yamauchi, R. Arakane and M. Shionoya, J. Am.
Chem. Soc. 2009, 131, 11646-11647.
7 G. L. Ning, M. Munakata, L. P. Wu, M. Maekawa, T. Kuroda-
Sowa, Y. Suenaga, and K. Sugimoto, Inorg. Chem. 1999, 38
1
,
376-1377.
8
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins