Synthesis, crystal structure, and luminescent properties of metal complexes bearing 2,6-pyridine-diacylhydrazide ligands: Supramolecular assemblies via intermolecular interactions

Article abstract of DOI:10.1007/s11243-011-9479-x

Four metal complexes of N,N′-bis(salicyl)-2,6-pyridine- dicarbohydrazide ligand (H₆L), [Co^II(H₄L) (H₂O)₂]?2DMF (1), [Zn^II(H ₄L)(H₂O)₂]?2DMF (2), [Cd ^II

Full text of DOI:10.1007/s11243-011-9479-x

Transition Met Chem (2011) 36:369–378
DOI 10.1007/s11243-011-9479-x
Synthesis, crystal structure, and luminescent properties of metal
complexes bearing 2,6-pyridine-diacylhydrazide ligands:
supramolecular assemblies via intermolecular interactions
Su-Ni Qin
Wan-Yun Huang
•
Zi-Lu Chen
•
•
Dong-Cheng Liu
•
Fu-Pei Liang
Received: 26 January 2011 / Accepted: 7 March 2011 / Published online: 25 March 2011
Ó Springer Science+Business Media B.V. 2011
0
Abstract Four metal complexes of N,N -bis(salicyl)-2,6-
II
of catalysis, electronics, nonlinear optics, magnetic mate-
pyridine-dicarbohydrazide ligand (H L), [Co (H L)(H O) ]ꢀ
rial, porous materials, and other technologies [1–10]. The
process of the self-assembly of a supramolecular frame-
work is based on the extension of individual molecules by
noncovalent or weak covalent interactions, including Van
der Waals, electrostatic and hydrophobic interactions,
hydrogen bonds, as well as p–p and ion-p stacking [11–
21]. Among these, hydrogen bonding and p–p stacking
interactions have been considered to play active roles in the
formation of ordered supramolecular chains, layers, and
three-dimensional frameworks, the research on which is of
great interest for the development of supramolecular
chemistry [22–29].
6
4
2
2
II
II
2
DMF (1), [Zn (H L)(H O) ]ꢀ2DMF (2), [Cd (H L)(Py) ]ꢀ
4
2
II III
2
4
2
DMFꢀPy (3), and [Co Co (H L) (H O) ]ꢀDMFꢀH O (4),
2
4
4
2
4
2
were synthesized and characterized by elemental analysis, IR,
and single-crystal X-ray diffraction analysis. Structural stud-
ies revealed that complexes 1–3 present discrete mononuclear
structures and complex 4 displays a centrosymmetric mixed-
valence trinuclear structure. All four complexes are further
extended into interesting two- or three-dimensional supra-
molecular frameworks. The luminescent properties of 2 and 3
were studied, which show emissions with maxima at 485 nm
uponexcitationat396 nmfor2 and476 nmuponexcitationat
3
97 nm for 3, respectively.
To date, many ligands have been used in the syntheses
of metal complexes as molecular building blocks for the
further self-assemblies of supramolecules. Among these
ligands, aromatic carboxylate-containing or amide-con-
taining ligands are often employed due to their facile
coordination to metal ions and inclination to form H-bonds
of COOHꢀꢀꢀN, COOHꢀꢀꢀO, and N–HꢀꢀꢀO, etc., as well as the
potential p–p stacking interaction between the aromatic
Introduction
Much effort has been paid to the design and synthesis of
supramolecular frameworks because of their versatile
architectures as well as potential applications in the fields
0
rings [14, 17, 19, 23, 30, 31]. N,N -bis(salicyl)-2,6-pyr-
idine-dicarbohydrazide (H L) ligand possesses eleven
6
potential donor groups (one pyridine group, four carbonyl
groups, two phenolic groups, and four amide moieties). It
provides not only sufficient metal binding sites, but also the
favorable conditions to generate intermolecular interac-
tions such as hydrogen bonding and p–p stacking interac-
tion. Thus, it is an excellent ligand for the construction of
supramolecules from its corresponding metal complexes.
Herein, we present the syntheses and structures of four
S.-N. Qin ꢀ Z.-L. Chen ꢀ D.-C. Liu ꢀ W.-Y. Huang ꢀ
F.-P. Liang (&)
Key Laboratory for the Chemistry and Molecular Engineering
of Medicinal Resources, Ministry of Education of China,
School of Chemistry and Chemical Engineering,
Guangxi Normal University, 541004 Guilin, China
e-mail: fliangoffice@yahoo.com
II
metal complexes with H L ligand, [Co (H L)(H O) ]ꢀ
6
4
2
2
S.-N. Qin ꢀ W.-Y. Huang
II
II
2
DMF (1), [Zn (H L)(H O) ]ꢀ2DMF (2), [Cd (H L)(Py) ]ꢀ
4
2
II III
2
4
2
State Key Laboratory of Coordination Chemistry, Coordination
Chemistry Institute, School of Chemistry and Chemical
Engineering, Nanjing University, 210093 Nanjing, China
DMFꢀPy (3), and [Co Co (H L) (H O) ]ꢀDMFꢀH O (4).
2
4
4
2
4
2
Complexes 1–3 possess similar mononuclear units, and
123

3
70
Transition Met Chem (2011) 36:369–378
complex 4 displays a centrosymmetric mixed-valence tri-
nuclear structure. With the aid of diverse intermolecular
interactions, they are further extended into interesting
two- or three-dimensional supramolecular frameworks. The
Photoluminescence properties of 2 and 3 were investigated.
C, 47.62; H, 4.88; N, 14.40. Found: C, 47.74; H, 5.01; N,
-
1
14.29. FT-IR (cm ): 3,454(s, br), 3,336(m), 3,321(m),
1,651(s), 1,605(s), 1,543(s), 1,492(s), 1,381(s), 1,306(m),
1,282(m), 1,101(m), 759(m).
II
Preparation of [Cd (H L)(Py) ]ꢀDMFꢀPy (3)
4
2
H L (0.0218 g, 0.05 mmol), Cd(NO ) ꢀ4H O (0.0463 g,
Experimental
6
3 2
2
0
.15 mmol), pyrazine (0.012 g, 0.15 mmol), DMF (0.5 mL),
pyridine (0.5 mL), and CH OH (0.2 mL) were placed in a
3
All reagents and solvents were purchased commercially
as reagent grade and used without further purification.
Elemental analyses were performed on a Perkin-Elmer
thick Pyrex tube (ca 20 cm long). The tube was frozen
using liquid N , evacuated under vacuum and flame-sealed.
2
Subsequently, it was allowed to warm to room temperature
2
400 II elemental analyzer. IR spectra were obtained in
and heated at 90 °C for 3 days, giving yellow block crys-
KBr pellets on a Nicolet 360 FTIR spectrometer in the
-
1
tals of 3 in a yield of 56%. Anal. Calc. for C H CdN O :
C, 54.71; H, 4.36; N, 14.72. Found: C, 54.57; H, 4.45; N,
range 4,000–400 cm . Solid-state luminescence spectra
were measured at room temperature on a FL3-PTCSPC
spectrophotometer with a xenon lamp as the light source.
39 37
9 7
-
1
1
4.87. FT-IR (cm ): 3,417(s, br), 3,342(m), 3,268(m),
,636(s), 1,607(s), 1,531(s), 1,491(s), 1,375(s), 1,307(m),
1
0
1,282(m), 1,101(m), 750(m).
Preparation of N,N -bis(salicyl)-2,6-pyridine-
dicarbohydrazide (H L)
6
II
III
2
Preparation of [Co Co (H L) (H O) ]ꢀDMFꢀH O (4)
4
4
2
4
2
The reaction of 2,6-pyridinedicarbonyl dichloride (1.70 g,
1
0 mmol) with salicyloyl hydrazide (3.3 g, 22 mmol) in
A methanol solution (5 mL) of Co(NO ) ꢀ6H O (0.0873 g,
3
2
2
THF for 3 days gave a white precipitate of H L, which was
6
0.3 mmol) was slowly added to a methanol solution (5 mL) of
isolated by filtration and recrystallized from methanol
solution (yield 85%). Anal. Calc. for C H N O (%): C,
H L (0.0435 g, 0.1 mmol). The resulting solution was further
6
stirred at ambient temperature for 9 h and then filtered. The
filtrate was allowed to evaporate at room temperature, giving
dark brown block crystals of 4 suitable for single-crystal
X-ray diffraction after 40 days (yield 38%). Anal. Calc. for
C H Co N O : C, 49.94; H, 4.00; N, 14.24. Found: C,
2
1 17 5 6
5
7.93; H, 3.93; N, 16.08. Found: C, 57.79; H, 3.79; N, 15.96.
-1
IR (KBr pellet, cm ): 3,340(m), 3,236(m), 1,706(m),
1
1
,640(m), 1,608(s), 1,547(m), 1,508(s), 1,489(s), 1,307(m),
,238(m), 759(m).
9
0
86
3 22 32
-
1
4
9.78; H, 4.11; N, 14.09. FT-IR (cm ): 3,371(s, br),
II
Preparation of [Co (H L)(H O) ]ꢀ2DMF (1)
3,254(m), 1,644(s), 1,623(s), 1,599(s), 1,514(s), 1,489(m),
1,371(m), 1,300(m), 1,248(m), 1,103(m), 760(m).
4
2
2
II
and [Zn (H L)(H O) ]ꢀ2DMF (2)
4
2
2
A methanol solution (5 mL) of CoCl ꢀ6H O (0.0714 g,
X-ray crystallography study
2
2
0
.3 mmol) was slowly added to a DMF solution (5 mL) of
H L (0.0435 g, 0.1 mmol). The resulting solution was
6
Suitable single crystals of complexes 1–4 were selected
and mounted onto thin glass fibers. The single-crystal
X-ray diffraction studies of 1, 2, and 4 were performed at
187(2) K and 3 at 185(2) K, using a Bruker CCD Area
Detector with graphite-monochromated Mo-Ka radiation
further stirred at ambient temperature for 9 h and then
filtered. The filtrate was allowed to evaporate at room
temperature, giving orange block crystals of 1 suitable for
single-crystal X-ray diffraction after 30 days (yield 45%).
Anal. Calc. for C H CoN O : C, 48.08; H, 4.93; N,
˚
(k = 0.71073 A). The program SAINT was used for inte-
gration of the diffraction profiles. The structures were
2
7
33
7 10
-
1
1
3
1
1
4.54. Found: C, 47.94; H, 5.07; N, 14.38. FT-IR (cm ):
,481(s, br), 3,334(m), 3,322(m), 1,648(s), 1,603(s), 1,592(s),
,566(s), 1,540(s), 1,494(s), 1,385(s), 1,307(m), 1,282(m),
,100(m), 759(m).
solved by direct methods using the SHELXS-97 program
2
package and refined against F by full-matrix least-squares
methods with SHELXL-97 [32, 33]. All non-hydrogen
atoms were refined with anisotropic thermal parameters.
Hydrogen atoms on C atoms were set in calculated posi-
tions and refined as riding atoms. The crystallographic data
are summarized in Table 1, and the selected bond lengths
and angles are listed in Table 2.
Complex 2 was prepared in a method similar to that for
using Zn(NO ) ꢀ6H O (0.0892 g, 0.3 mmol) instead of
1
3
2
2
CoCl ꢀ6H O. Colorless block crystals were obtained in a
2
2
yield of 42% by slow evaporation of the filtrate at room
temperature for 40 days. Anal. Calc. for C H ZnN O :
2
7
33
7 10
1
23

Transition Met Chem (2011) 36:369–378
371
Table 1 Crystallographic data and refinement summary for 1–4
1
2
3
4
Empirical formula
Formula weight
Crystal system
Space group
C
27
H
33CoN
7
O
10
C
27
H
33ZnN
7
O
10
C
39
H
37CdN
O
9 7
C
90 3 22 32
H86Co N O
674.53
680.97
856.18
2164.60
Triclinic
P¯ı
Monoclinic
Monoclinic
Monoclinic
P2
1
/c
P2
1
/c
1
P2 /c
˚
a (A)
16.6766 (11)
7.2424 (5)
24.4485 (17)
90
16.698 (5)
7.205 (5)
24.289 (5)
90
14.0912 (5)
20.0980 (6)
28.1697 (9)
90
13.2440 (5)
˚
b (A)
13.9350 (10)
14.6847 (6)
103.8260 (10)
112.7820 (10)
98.7340 (10)
2,334.2 (2)
1
˚
c (A)
a (°)
b (°)
c (°)
98.3980 (10)
90
98.308 (5)
90
104.3230 (10)
90
3
˚
V (A )
2,921.2 (3)
4
2,892 (2)
4
7,729.8 (4)
8
Z
-3
)
DCalc (g cm
1.534
1.564
1.471
1.540
-
1
)
l (Mo-Ka) (mm
h (°)
0.658
0.920
0.627
0.625
1.68–25.00
1.23–25.00
2.03–25.09
1.56–25.00
Reflections collected/unique (Rint
)
16,734/5,154 (0.0554)
1.047
16,791/5,096 (0.0943)
0.931
55,911/13,733 (0.0465)
1.040
16,880/8,203 (0.0158)
1.067
2
Goodness-of-fit on F
Final R indices [I [ 2r (I)]
R indices (all data)
R
1
= 0.0515,
= 0.1319
= 0.0894,
= 0.1450
0.916, -0.703
R
1
= 0.0455,
= 0.0947
= 0.1083,
= 0.1242
0.422, -0.522
R
1
= 0.0384,
= 0.0899
= 0.0539,
= 0.0986
1.220, -0.969
R
1
= 0.0319,
= 0.0912
= 0.0366,
= 0.0937
0.597, -0.460
wR
2
wR
2
wR
2
wR
2
R
1
R
1
R
1
R
1
wR
2
wR
2
wR
2
wR
2
-3
)
Largest diff. peak and hole (e A
˚
Table 2 Selected bond distances (A) and bond angles (°) for 1–4
1
Co1–O7
2.143 (3)
2.144 (3)
Co1–N5
Co1–O1
2.164 (3)
Co1–N1
2.218 (3)
Co1–N3
2.217 (2)
Co1–O3
2.252 (2)
Co1–O8
2.153 (3)
O7–Co1–N3
O7–Co1–O8
N3–Co1–O8
O7–Co1–N5
N3–Co1–N5
O8–Co1–N5
O7–Co1–O1
2
91.72 (10)
174.63 (9)
89.21 (10)
90.67 (11)
139.68 (11)
92.05 (11)
87.49 (10)
N3–Co1–O1
O8–Co1–O1
N5–Co1–O1
O7–Co1–N1
N3–Co1–N1
O8–Co1–N1
N5–Co1–N1
71.77 (10)
87.77 (10)
148.55 (10)
92.25 (10)
69.85 (10)
93.03 (10)
69.84 (10)
O1–Co1–N1
O7–Co1–O3
N3–Co1–O3
O8–Co1–O3
N5–Co1–O3
O1–Co1–O3
N1–Co1–O3
141.59 (10)
86.79 (9)
149.90 (11)
89.76 (9)
70.42 (10)
78.13 (9)
140.23 (10)
Zn1–O7
2.111 (3)
2.119 (3)
Zn1–N5
Zn1–N1
2.181 (4)
2.221 (3)
Zn1–O1
Zn1–O3
2.240 (3)
2.333 (3)
Zn1–O8
Zn1–N3
2.150 (3)
O7–Zn1–O8
O7–Zn1–N3
O8–Zn1–N3
O7–Zn1–N5
O8–Zn1–N5
N3–Zn1–N5
O7–Zn1–N1
171.73 (11)
91.88 (12)
90.46 (12)
90.79 (13)
92.48 (13)
140.24 (13)
93.33 (12)
O8–Zn1–N1
N3–Zn1–N1
N5–Zn1–N1
O7–Zn1–O1
O8–Zn1–O1
N3–Zn1–O1
N5–Zn1–O1
94.92 (12)
70.07 (13)
70.17 (13)
86.58 (12)
86.62 (12)
71.75 (12)
148.00 (12)
N1–Zn1–O1
O7–Zn1–O3
O8–Zn1–O3
N3–Zn1–O3
N5–Zn1–O3
N1–Zn1–O3
O1–Zn1–O3
141.80 (12)
86.80 (11)
87.24 (11)
150.27 (12)
69.49 (12)
139.66 (12)
78.52 (10)
123

3
72
Transition Met Chem (2011) 36:369–378
Table 2 continued
3
Cd1–N4
2.333 (3)
2.348 (3)
2.355 (3)
2.356 (3)
2.460 (3)
98.40 (10)
92.04 (10)
163.33 (10)
129.42 (9)
91.32 (10)
92.03 (10)
64.85 (9)
99.43 (10)
96.76 (9)
64.61 (9)
66.40 (8)
85.80 (9)
86.53 (9)
164.17 (8)
Cd1–O5
2.468 (2)
2.529 (2)
2.328 (3)
2.350 (3)
2.357 (3)
131.22 (8)
164.51 (9)
83.18 (9)
83.34 (9)
65.70 (8)
130.29 (8)
98.48 (7)
129.41 (9)
95.68 (10)
89.88 (10)
92.81 (10)
95.06 (10)
164.14 (10)
162.97 (9)
Cd2–N13
Cd2–O8
Cd2–N8
Cd2–O11
2.366 (3)
2.394 (2)
2.465(3)
2.504 (2)
Cd1–N12
Cd1–O2
Cd1–N11
Cd2–N9
Cd1–N2
Cd2–N7
Cd1–N3
Cd2–N14
N4–Cd1–N12
N4–Cd1–N11
N12–Cd1–N11
N4–Cd1–N2
N12–Cd1–N2
N11–Cd1–N2
N4–Cd1–N3
N12–Cd1–N3
N11–Cd1–N3
N2–Cd1–N3
N4–Cd1–O5
N12–Cd1–O5
N11–Cd1–O5
N2–Cd1–O5
4
N3–Cd1–O5
N4–Cd1–O2
N12–Cd1–O2
N11–Cd1–O2
N2–Cd1–O2
N3–Cd1–O2
O5–Cd1–O2
N9–Cd2–N7
N9–Cd2–N14
N7–Cd2–N14
N9–Cd2–N13
N7–Cd2–N13
N14–Cd2–N13
N9–Cd2–O8
N7–Cd2–O8
N14–Cd2–O8
N13–Cd2–O8
N9–Cd2–N8
N7–Cd2–N8
N14–Cd2–N8
N13–Cd2–N8
O8–Cd2–N8
N9–Cd2–O11
N7–Cd2–O11
N14–Cd2–O11
N13–Cd2–O11
O8–Cd2–O11
N8–Cd2–O11
67.61 (9)
83.70 (9)
84.27 (10)
65.19 (9)
64.23 (9)
95.64 (9)
100.09 (10)
131.84 (8)
66.42 (8)
164.16 (8)
87.73 (9)
83.41 (9)
96.56 (8)
131.59 (8)
Co1–N1
1.8571 (15)
1.8638 (15)
1.9267 (16)
1.9314 (15)
1.9391 (16)
178.15 (7)
81.21 (7)
Co1–N7
1.9554 (16)
2.0654 (15)
2.0654 (15)
2.0973 (14)
2.0973 (14)
99.42 (6)
81.24 (6)
88.87 (7)
94.33 (7)
162.26 (7)
180.0
Co2–O14
2.1279 (15)
2.1279 (15)
1.246 (2)
i
i
Co1–N2
Co2–O13
Co2–O14
Co1–N3
Co2–O13
Co2–O1
O1–C1
N3–C1
Co1–N5
1.328 (3)
i
Co1–N9
Co2–O1
i
N1–Co1–N2
N1–Co1–N3
N2–Co1–N3
N1–Co1–N5
N2–Co1–N5
N3–Co1–N5
N1–Co1–N9
N2–Co1–N9
N3–Co1–N9
N5–Co1–N9
N1–Co1–N7
N2–Co1–N7
N3–Co1–N7
N5–Co1–N7
N9–Co1–N7
i
O13 –Co2–O13
i
O13 –Co2–O1
O1–Co2–O1
i
O13 –Co2–O14
180.000 (1)
90.81 (6)
89.19 (6)
91.29 (6)
88.71 (6)
89.19 (6)
90.81 (6)
88.71 (6)
91.29 (6)
180.00 (7)
97.09 (7)
O13–Co2–O14
O1–Co2–O14
i
O1 –Co2–O14
81.36 (6)
100.33 (7)
162.56 (7)
98.31 (7)
i
O13 –Co2–O14
i
i
86.42 (6)
93.58 (6)
93.58 (6)
86.42 (6)
O13–Co2–O14
i
O1–Co2–O14
i
O1 –Co2–O14
81.03 (7)
O13–Co2–O1
i
O13 –Co2–O1
i
i
94.00 (7)
i
i
88.16 (7)
O13–Co2–O1
O14–Co2–O14
Symmetry codes: (i) -x ? 2, -y, -z ? 1
II
II
Results and discussion
chelating ligand. It coordinates to one Co or Zn ion using
one Npyridyl atom (N1), two Npyridyl-acylamide atoms (N3 and
N5), and two Obenzyl-acylamide atoms (O1 and O3) to form a
mononuclear molecule as shown in Fig. 1. The Opyridyl-
acylamide, Nbenzyl-acylamide, and Ophenolic atoms of the ligand
Structure descriptions of complexes 1 and 2
The isostructural complexes 1 and 2, which present
mononuclear structures, crystallize in the monoclinic space
are free from coordination. The five coordinating atoms
2-
II
group P2 /c. Co ion in 1 and Zn ion in 2 are both seven-
II
of H4L
complete the equatorial plane and the mean
1
˚
deviations are 0.0132 A for 1 and 0.0107 A for 2, indicating
˚
coordinated in pentagonal bipyramidal geometries. The
2
divalent anionic H4L in 1 and 2 behaves a pentadentate
-
that the five atoms are nearly coplanar. Such planarity was
1
23

Transition Met Chem (2011) 36:369–378
373
Fig. 1 The perspective views
of the structures of 1 (a) and 2
(b). H atoms and guest DMF
molecules are omitted for clarity
Structure description of complex 3
Complex 3 crystallizes in the monoclinic space group
P2 /c and presents two discrete mononuclear units
1
II
Cd (H L)(Py) ], which are similar to the mononuclear
[
4
2
II
unit [M (H L)(H O) ] of complexes 1 and 2. The struc-
4
2
2
tural difference of 3 from 1 and 2 is that the two axial sites
of the metal are occupied by two pyridine ligands in 3,
rather than the two water ligands in 1 and 2. This might be
due to the strong coordinating ability of pyridine solvent
used in the synthesis of 3. The five coordinated atoms (one
Npyridyl, two Npyridyl-acylamide, and two Obenzyl-acylamide
2
-
atoms) of H4L
are nearly coplanar with the mean devi-
˚
Fig. 2 2D network formed by type A and type B hydrogen bonds
indicated by broken lines of 1
ations of 0.0120 and 0.0331 A for the two mononuclear
units.
There are p–p stacking interactions between the benzyl
rings from the two mononuclear molecules in 3 (Fig. 3).
The dihedral angles and centroid-to-centroid distances
observed in the reported complex [Cd(C H N O )-
1
5 11 5 8
0
˚
(
H O) ]ꢀ2C H NO (C H N O = N,N -bis(3-carboxy-
of adjacent benzyl rings are 2.7168 and 3.570 A (rings a
2
2
3
7
15 11 5 8
˚
cis-propenoyl)-2, 6-picolyldihydrazide) [34]. The remain-
and b), 3.1198 and 3.634 A (rings c and d), respectively.
Furthermore, the adjacent units of 3 form hydrogen bonds
II
II
ing axial sites of the Co or Zn are occupied by two
oxygen atoms (O7 and O8) from two water ligands.
Complexes 1 and 2 exhibit similar hydrogen bonds.
Thus, only the hydrogen bonds of 1 are discussed here in
detail. As shown in Fig. 2, one uncoordinated phenolic
i
ii
iii
O1–H1AꢀꢀꢀO10 , O6–H6AꢀꢀꢀO9 , O7–H7AꢀꢀꢀO4 , O12–
iv
H12BꢀꢀꢀO3 (i = x, -y ? 1/2, z ? 1/2; ii = x ? 1, y, z;
iii = x - 1, y, z; iv = x, -y ? 1/2, z - 1/2) between the
phenolic groups from one unit and the Opyridyl-acylamide
atoms from the adjacent units, with the OꢀꢀꢀO distances and
i
group forms hydrogen bonds O6–H6AꢀꢀꢀO4 (i = -x ? 1,
˚
-
y ? 1, -z ? 1) with an O
adjacent unit, composing type A hydrogen bonds with the
atom from the
O–HꢀꢀꢀO angles in the ranges of 2.54–2.61 A and 169°–
pyridyl-acylamide
177°, respectively (Table 3). With the aid of these p–p
stacking and hydrogen bonding interactions, complex 3 is
extended into a two-dimensional supramolecular network
as shown in Fig. 4.
˚
OꢀꢀꢀO distance of 2.592 A. The two water ligands at axial
positions of 1 form hydrogen bonds simultaneously with
the oxygen atom of one guest DMF molecule and one
ii
Opyridyl-acylamide atom (O7–H7AꢀꢀꢀO2 , O7–H7BꢀꢀꢀO10,
iii
iv
O8–H8AꢀꢀꢀO2 and O8–H8BꢀꢀꢀO10 , ii = -x, -y ? 1,
Structure description of complex 4
-
z ? 1; iii = -x, -y, -z ? 1; iv = x, y - 1, z), com-
posing type B hydrogen bonds with the OꢀꢀꢀO distances
The single-crystal X-ray structural analysis reveals that
complex 4 has a centrosymmetric mixed-valence trinu-
clear structure, which crystallizes in the triclinic space
˚
and O–HꢀꢀꢀO angles in the ranges of 2.69–2.88 A and
1698–1758, respectively (Table 3). As a result, complex 1
is further extended into a two-dimensional supramolecular
II
III
group P ¯ı . There are one Co and two Co ions in 4, as
established by charge balance considerations and bond
network by type A and type B hydrogen bonds.
123

3
74
Transition Met Chem (2011) 36:369–378
Table 3 Hydrogen bonds
A˚ and °) for 1–4
D–HꢀꢀꢀA
D–H
HꢀꢀꢀA
DꢀꢀꢀA
\D–HꢀꢀꢀA
Symmetry code on A
(
1
(2 exhibits similar hydrogen bonds)
N2–H2AꢀꢀꢀO5
N4–H4BꢀꢀꢀO6
O5–H5BꢀꢀꢀO9
O6–H6AꢀꢀꢀO4
O7–H7AꢀꢀꢀO2
O7–H7BꢀꢀꢀO10
O8–H8AꢀꢀꢀO2
O8–H8BꢀꢀꢀO10
3
0.88
0.88
0.84
0.84
0.85
0.84
0.84
0.85
1.97
2.02
1.76
1.75
1.85
2.04
1.93
1.99
2.633
2.678
2.590
2.592
2.697
2.865
2.766
2.832
131.0
130.4
170.4
175.8
174.1
169.6
172.0
167.9
-x, y - 1/2, -z ? 1/2
-x ? 1, -y ? 1, -z ? 1
-x, -y ? 1, -z ? 1
-x, -y, -z ? 1
x, y - 1, z
N10–H10ꢀꢀꢀO12
N6–H6ꢀꢀꢀO7
0.88
0.88
0.88
0.88
0.84
0.84
0.84
0.84
1.89
1.92
1.91
1.89
1.75
1.71
1.77
1.73
2.592
2.608
2.607
2.590
2.584
2.546
2.602
2.567
135.5
133.9
134.4
135.7
171.0
176.9
169.9
170.6
N5–H5ꢀꢀꢀO6
N1–H1ꢀꢀꢀO1
O12–H12BꢀꢀꢀO3
O7–H7AꢀꢀꢀO4
O6–H6AꢀꢀꢀO9
O1–H1AꢀꢀꢀO10
4
x, -y ? 1/2, z - 1/2
x - 1, y, z
x ? 1, y, z
x, -y ? 1/2, z ? 1/2
N4–H4BꢀꢀꢀO1 W
N6–H6BꢀꢀꢀO7
N8–H8AꢀꢀꢀO4
N10–H10BꢀꢀꢀO12
N10–H10BꢀꢀꢀO3
O5–H5BꢀꢀꢀO3
O6–H6AꢀꢀꢀO4
O11–H11BꢀꢀꢀO9
O12–H12BꢀꢀꢀO2
O13–H13AꢀꢀꢀO10
O13–H13BꢀꢀꢀO15
O14–H14AꢀꢀꢀO15
O14–H14BꢀꢀꢀO1 W
O1 W–H1 WAꢀꢀꢀO10
O1W–H1WBꢀꢀꢀO8
0.88
0.88
0.88
0.88
0.88
0.84
0.84
0.84
0.84
0.85
0.85
0.85
0.85
0.85
0.85
1.95
2.03
2.62
2.09
2.25
1.81
1.86
1.86
1.74
1.86
1.88
2.00
1.92
1.89
1.85
2.768
2.844
3.190
2.679
2.962
2.553
2.601
2.598
2.577
2.708
2.690
2.797
2.756
2.719
2.693
153.4
154.3
123.0
123.7
137.5
146.1
146.7
145.8
174.8
174.4
159.2
155.9
166.3
166.4
173.6
-x ? 2, -y, -z ? 1
-x ? 1, -y - 1, -z ? 1
-x ? 1, -y - 1, -z
-x ? 2, -y, -z ? 1
x, y ? 1, z
II
valence sum (BVS) calculations (BVS for the Co and
atoms, that is, two Npyridyl atoms (N1 and N2) and four
atoms (N3, N5, N7, and N9) from two
III
Co ions were 2.014 and 3.108, respectively) as shown
N
pyridyl-acylamide
2
H4L ligands (Fig. 5).
-
in Table 4 [35–37]. The central divalent Co2 is six-
coordinated in a regular octahedral geometry by two
2
The H4L ligands in 4 present two kinds of coordina-
-
2
-
Opyridyl-acylamide atoms (O1 and O1A) from two H4L
tion modes. One is tridentate chelating mode coordinating
III
ligands and four oxygen atoms (O13, O13A, O14, and
to Co1 ion using its Npyridyl atom and two Npyridyl-acylamide
4
III
O14A) from four water molecules. The bond distances of
atoms. The other one is l -g -bridging mode linking Co1
2
2
C–O and C–N in pyridyl-acylamide groups of H4L are
-
II
and Co2 via the coordination of three nitrogen atoms
III
mentioned above to Co1 and the coordination of Opyridyl-
˚
1
.246 and 1.328 A, respectively, suggesting that the CO
and CN groups coordinate to cobalt in the enolic form
38]. Co1 and Co1A are both trivalent and six-coordi-
II
to Co2 , resulting in the formation of a trinuclear
acylamide
[
structure of 4 as shown in Fig. 5. All of the Obenzyl-acylamide,
2-
nated in distorted octahedral geometries. The six coor-
dinating sites of Co1 (Co1A) are all occupied by nitrogen
Nbenzyl-acylamide, and Ophenolic atoms of H4L in 4 are free
from coordination.
1
23

Transition Met Chem (2011) 36:369–378
375
2-
the Obenzyl-acylamide, Nbenzyl-acylamide atoms of H4L ligands
from one 2D sheet (O14–H14BꢀꢀꢀO1W, O1W–H1WAꢀꢀꢀ
iii
iii
O10 and N4–H4BꢀꢀꢀO1W , iii = -x ? 2, -y, -z ? 1),
and the O
atom from the adjacent sheet (O1W–
pyridyl-acylamide
iv
˚
H1WBꢀꢀꢀO8 at OꢀꢀꢀO = 2.844 A, iv = x, y ? 1, z). These
hydrogen bonds connect the 2D networks into a 3D supra-
molecular framework of 4 as shown in Fig. 7.
Structural discussion
0
The doubly deprotonated N,N -bis(salicyl)-2,6-pyridine-
2
dicarbohydrazide (H4L ) in 1–3 chelates to one metal
-
atom as a pentadentate ligand to form similar mononuclear
2
structures. However, the four H L ligands in 4 coordi-
-
4
III
nate to Co1 or Co1A in a tridentate chelating mode
III
Fig. 3 The perspective view of two mononuclear units in 3, showing
the p–p stacking interactions indicated by broken lines. H atoms,
guest pyridine and DMF molecules are omitted for clarity
II
with two of them further binding to Co2 using the O
pyridyl-
atom, resulting in the formation of a trinuclear
acylamide
structure for 4. Complexes 1–4 are further extended into
interesting two- or three-dimensional supramolecular
frameworks via diverse intermolecular interactions.
In complexes 1 and 2, the mononuclear units are both
linked into 2D supramolecular networks by type A hydrogen
bonds between the phenolic group and O
pyridyl-acylamide
2
-
atom of neighboring H4L ligands, and type B hydrogen
bonds between water ligands, guest DMF molecules, and
Opyridyl-acylamide ligand atoms. The presence of abundant
hydrogen bonds in 1 and 2 is attributed to the water ligands
and guest DMF molecules. Different from 1 and 2, the
presence of coordinated and guest pyridine molecules in 3
blocks the formation of hydrogen bonds from the solvent
molecules. As a result, hydrogen bonds in complex 3 are
Fig. 4 2D network formed by the p–p stacking and hydrogen
bonding interactions (indicated by broken lines) of 3
formed only between the phenolic group and O
pyridyl-acyla-
a
Table 4 Bond Valence Sum (BVS) calculations for the cobalt ions
in 4
2
atom of neighboring H4L ligands. However, there
-
mide
are p–p stacking interactions between the two discrete
mononuclear units in 3, which, together with hydrogen
bonds, helps to construct a 2D supramolecular network of 3
different from those of 1 and 2. In the case of complex 4,
the trinuclear units are linked into 1D chains via hydrogen
bonds between the uncoordinated benzyl-acylamide group
II
III
Co
Co
Co1 (Co1A)
3.788
2.014
3.108
2.058
Co2
a
The underlined value is the one closest to the charge for which it
was calculated. The oxidation state of a particular atom can be taken
as the nearest whole number to the underlined value [39]
2-
and the Opyridyl-acylamide atom of H4L ligands. These 1D
chains are further connected into a 2D network by hydro-
gen bonds involving the phenolic group and the O
pyridyl-
As depicted in Fig. 6 and Table 3, trinuclear units of 4
are linked into 1D chains via intermolecular hydrogen
bonds between the uncoordinated benzyl-acylamide group
and the Opyridyl-acylamide atom from the neighboring trinu-
2
atom of H4L ligands. Due to the presence of a
-
acylamide
guest water molecule, which forms hydrogen bonds with
II
the water ligand on central Co2 and the Obenzyl-acylamide,
2-
i
Nbenzyl-acylamide, and Opyridyl-acylamide atoms of H4L
clear unit (N6–H6BꢀꢀꢀO7 with an OꢀꢀꢀO distance of 2.844
ligands, the 3D supramolecular framework of 4 is built.
˚
A, i = -x ? 1, -y - 1, -z ? 1). These 1D chains are
further connected into a 2D network by interchain H-bonds
ii
O12–H12BꢀꢀꢀO2 (ii = -x ? 1, -y - 1, -z) between the
Luminescent properties
phenolic group and the O
atom from the
pyridyl-acylamide
adjacent chains (Fig. 6). The guest water molecule in 4
II
forms hydrogen bonds with one water ligand on Co2 and
The solid-state luminescent properties of complexes 2 and
3, as well as the free H L ligand, were investigated at room
6
123

3
76
Transition Met Chem (2011) 36:369–378
Fig. 5 The perspective view of
the trinuclear structure of 4. H
atoms, guest H O, and DMF
2
molecules are omitted for
clarity. Symmetry codes: A)
-
x ? 2, –y, -z ? 1
Fig. 6 1D chain and 2D
network formed by hydrogen
bonds (indicated by broken
lines) of 4
Fig. 7 3D hydrogen-bonded
framework of 4
temperature as shown in Fig. 8. The emission spectrum of
the free ligand displays a band with a maximum at
excitation at 397 nm for 3, respectively, which are
assigned to intraligand transitions. These emissions are
2
-
4
46 nm when excited at 372 nm, which corresponds to
slightly disturbed by the coordination of H4L to metal
ions [40].
the p ? p* transition of the ligand. The complexes
exhibit characteristic luminescence with maximum at
The emission decay profiles of complexes 2 and 3 in the
solid state were obtained at room temperature. The lifetime
4
85 nm upon excitation at 396 nm for 2 and 476 nm upon
1
23

Transition Met Chem (2011) 36:369–378
377
Acknowledgments This work was supported by the National Natural
Science Foundation of China (No. 20971029), Guangxi Natural Science
Foundation (No. 2010GXNSFD013018 and 2010GXNSFF013001).
References
1
2
. Brunet P, Simard M, Wuest JD (1997) J Am Chem Soc 119:2737
. Wilkinson MJ, van Leeuwen PWNM, Reek JNH (2005) Org
Biomol Chem 3:2371
3
4
. Kleij AW (2009) Dalton Trans 4635
. Li Y, He YM, Li ZW, Zhang F, Fan QH (2009) Org Biomol
Chem 7:1890
. Au RHW, Jennings MC, Puddephatt RJ (2009) Dalton Trans
5
6
7
8
9
3
519
. Rodriguez-Llansola F, Miravet JF, Escuder B (2009) Chem
Commun 7303
. Martins FT, Paparidis N, Doriguetto AC, Ellena J (2009) Cryst
Growth Des 9:5283
. Lam CK, Xue F, Zhang JP, Chen XM, Mak TCW (2005) J Am
Chem Soc 127:11536
Fig. 8 Fluorescence emission spectra of complexes 2 (red) and 3
(blue) and the free ligand (black) in the solid state at room
temperature
. Chen XD, Wan CQ, Sung HHY, Williams ID, Mak TCW (2009)
Chem Eur J 15:6518
0. Mak TCW, Zhao L (2007) Chem Asian J 2:456
of the 485 nm emission for 2 is 0.61 ns, longer than that of
the 476 nm emission for 3 (0.32 ns).
1
11. Chen XD, Guo JH, Du M, Mak TCW (2005) Inorg Chem
Commun 8:766
1
2. Tzeng BC, Huang YC, Chen BS, Wu WM, Lee SY, Lee GH,
Peng SM (2007) Inorg Chem 46:186
3. Han J, Yau CW, Lam CK, Mak TCW (2008) J Am Chem Soc
Conclusion
1
1
30:10315
14. Wan CQ, Li GS, Chen XD, Mak TCW (2008) Cryst Growth Des
:3897
0
In this work, N,N -bis(salicyl)-2,6-pyridine-dicarbohy-
8
drazide-containing metal complexes 1–4 were synthe-
sized and structurally characterized. Complexes 1–3
exhibit similar mononuclear unit, and complex 4 presents
a centrosymmetric mixed-valence trinuclear structure.
All complexes are further extended into interesting two-
or three-dimensional supramolecular frameworks. Com-
plexes 1 and 2 present 2D supramolecular networks
formed by the assembly of mononuclear units via two
types of H-bonds. Complex 3 shows a 2D supramolecular
network built by hydrogen bonds and p–p stacking
interactions, which is different from those of 1 and 2 due
to the presence of coordinated and guest pyridine mole-
cules in 3 instead of the coordinated water ligands and
guest DMF molecules in 1 and 2. Complex 4 displays a
1
5. Wang CJ, Wang YY, Liu JQ, Wang H, Shi QZ, Peng SM (2009)
Inorg Chim Acta 362:543
16. Tadokoro M, Shiomi T, Kaneyama M, Miyazato Y (2009) J
Nanosci Nanotechnol 9:301
1
7. Das A, Choudhury SR, Dey B, Yalamanchili SK, Helliwell M,
Gamez P, Mukhopadhyay S, Estarellas C, Frontera A (2010) J
Phys Chem B 114:4998
18. Choudhury SR, Lee HM, Hsiao T-H, Colacio E, Jana AD,
Mukhopadhyay S (2010) J Mol Struct 967:131
1
9. Keene TD, Zimmermann I, Neels A, Sereda O, Hauser J, Liu SX,
Decurtins S (2010) Cryst Growth Des 10:1854
0. Zhang KL, Chang Y, Hou CT, Diao GW, Wu RT, Ng SW (2010)
CrystEngComm 12:1194
2
2
2
1. Cavalli S, Albericio F, Kros A (2010) Chem Soc Rev 39:241
2. Gu JZ, Lv DY, Gao ZQ, Liu JZ, Dou W (2011) Transition Met
Chem 36:53
23. Koner R, Goldberg I (2009) CrystEngComm 11:1217
24. Aakeroy CB, Seddon KR (1993) Chem Soc Rev 22:397
3
D supramolecular framework constructed via hydrogen
2
2
2
5. Sherrington DC, Taskinen KA (2001) Chem Soc Rev 30:83
6. Cooke G, Rotello VM (2002) Chem Soc Rev 31:275
7. Andrews PC, Gee WJ, Junk PC, Krautscheid H, MacLellan JG
bonding interaction with the participation of guest water
molecule. The fluorescence measurements revealed emissions
with maximum at 485 nm upon excitation at 396 nm for 2
and 476 nm upon excitation at 397 nm for 3, respectively.
(
2010) Chem Commun 46:5948
28. Eseola AO, Li W, Gao R, Zhang M, Hao X, Liang T, Obi-Egbedi
NO, Sun WH (2009) Inorg Chem 48:9133
2
3
3
3
9. Reger DL, Horger J, Smith MD, Long GJ (2009) Chem Commun
219
0. Zhang KL, Chang Y, Hou CT, Diao GW, Wu R, Ng SW (2010)
CrystEngComm 12:1194
1. Kirillova MV, Guedes da Silva MFC, Kirillov AM, Fra u´ sto da
Silva JJR, Pombeiro AJL (2007) Inorg Chim Acta 360:506
2. Sheldrick GM (1997) SHELX-97, Program for crystal structure
refinement. University of G o¨ ttingen, Germany
6
Supplementary material
CCDC 797380–797383 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
33. Sheldrick GM (2008) Acta Crystallogr Sect A 64:112
123

3
78
Transition Met Chem (2011) 36:369–378
3
3
3
3
3
4. Cao QF, Li DC (2009) Acta Crystallogr Sect E 65:m464
5. Brown ID, Altermatt D (1985) Acta Crystallogr Sect B 41:244
6. Brese NE, O’Keeffe M (1991) Acta Crystallogr Sect B 47:192
7. Liu WT, Thorp HH (1993) Inorg Chem 32:4102
39. Stamatatos TC, Foguet-Albiol D, Stoumpos CC, Raptopoulou CP,
Terzis A, Wernsdorfer W, Perlepes SP, Christou G (2005) J Am
Chem Soc 127:15380
40. Xiong RG, Zuo JL, You XZ, Abrahams BF, Bai ZP, Che CM,
Fun HK (2000) Chem Commun 2061
8. Wu WS, Liu SX (2004) Chin J Struct Chem 23:105
1
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