Three new Salamo-type homotrinuclear nickel(II) complexes possessing solvent effects: Syntheses, structures and fluorescence properties

Article abstract of DOI:10.1016/j.poly.2017.02.033

Three new solvent-induced Ni(II) complexes with the chemical formulae [{Ni(L)(CH₃OH)}₂(μ-OAc)₂Ni] (1), [{Ni(L)(C₃H₇OH)}₂(μ-OAc)₂Ni] (2) and [{NiL(H₂O)}₂(μ-O

Full text of DOI:10.1016/j.poly.2017.02.033

Accepted Manuscript
Three new Salamo-type homotrinuclear nickel(II) complexes possessing solvent
effects: Syntheses, structures and fluorescence properties
Lu-Mei Pu, Hai-Tao Long, Yang Zhang, Yang Bai, Wen-Kui Dong
PII:
S0277-5387(17)30155-9
DOI:
http://dx.doi.org/10.1016/j.poly.2017.02.033
POLY 12500
Reference:
Polyhedron
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Revised Date:
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22 December 2016
4 February 2017
4 February 2017
Please cite this article as: L-M. Pu, H-T. Long, Y. Zhang, Y. Bai, W-K. Dong, Three new Salamo-type
homotrinuclear nickel(II) complexes possessing solvent effects: Syntheses, structures and fluorescence properties,
Polyhedron (2017), doi: http://dx.doi.org/10.1016/j.poly.2017.02.033
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Three new Salamo-type homotrinuclear nickel(II)
complexes possessing solvent effects: Syntheses,
structures and fluorescence properties
Lu-Mei Pu a,*, Hai-Tao Long a, Yang Zhang b, Yang Bai b, Wen-Kui Dong b
a
College of Science, Gansu Agricultural University, Lanzhou, Gansu, 730070,
P.R.China
b
School of Chemical and Biological Engineering, Lanzhou Jiaotong University,
Lanzhou, Gansu, 730070, P.R.China
Abstract
Three new solvent-induced Ni(II) complexes with the chemical formulae
[{Ni(L)(CH3OH)}2(µ-OAc)2Ni] (1), [{Ni(L)(C3H7OH)}2(µ-OAc)2Ni] (2) and
[{NiL(H2O)}2(µ-OAc)2Ni] (3) were synthesized by the reaction of the Salamo-type
ligand 4,4ꢀ-dinitro-2,2ꢀ-[1,2-ethylene-dioxybis(nitrilomethylidyne)]diphenol (H2L)
with Ni(II) acetate tetrahydrate in different solvents and characterized by elemental
analyses, FT-IR, UV-Vis spectra and X-ray crystallography. X-ray crystallographic
analyses indicate that complexes 1, 2 and 3 have similar structures, consisting of three
Ni(II) atoms, two completely deprotonated (L)2- units, two µ-acetate ions and two
coordinated solvent (methanol, n-propanol and H2O) molecules, thereby forming
slightly distorted octahedral geometries. Although the Ni(II) atoms are all
hexa-coordinated in these complexes, there are obvious differences in their crystal and
supramolecular structures due to solvent effects: Complex 1 forms an infinite 2D
network structure, while complexes 2 and 3 form infinite 3D supramolecular
structures by strong hydrogen bonding interactions.
* Corresponding authors.
E-mail addresses: pulm@gsau.edu.cn (L.-M. Pu).
1

Keywords: Salamo-type ligand, Ni(II) complex, Crystal structure, Fluorescence
property, Solvent effect
1. Introduction
Schiff-base compounds constitute an important class of ligands which have
been extensively investigated in coordination chemistry mainly due to their facile
synthesis and easily tunable steric, electronic and catalytic properties. They are also
useful in constructing supramolecular structures [1]. Nowadays Salen-type transition
metal complexes have become an important research field [2]. These complexes can
be used in catalysts [3,4], photonic devices [5], magnetic materials [6], models of
biological [7] and electrochemical systems [8]. Furthermore, Salen-Ni(II) complexes
are used extensively in the design and construction of new magnetic materials and
models for the Ni(II) centers of enzymes. These complexes can be used to obtain
non-linear optical materials [9], models of biological systems [10], interesting
magnetic properties [11] and building blocks for cyclic supramolecular structures
[12]. Thus, new materials can be produced by using these compounds, which are
suitable candidates for further chemical modifications [13]. If an O-alkyl oxime
moiety (–CH=N–O–(CH2)n–O–N=CH–) is used instead of a Schiff base, the larger
electronegativity of the oxygen atoms is expected to affect strongly the electronic
properties of the N2O2 coordination sphere, which may lead to novel and different
structures and properties of the resulting complexes [1,2]. Solvent effects can lead to
better ways to control supramolecular interactions [14a]. With this in mind, we have
designed
and
synthesized
a
Salamo-type
ligand,
4,4ꢀ-dinitro-2,2ꢀ-[1,2-ethylene-dioxybis(nitrilomethylidyne)]diphenol (H2L), and its
supramolecular trinuclear Ni(ꢁꢁ) complexes 1, 2 and 3.
2. Experimental
2.1. Materials and instruments
All chemicals were of analytical reagent grade and were used without further
2

purification. C, H and N analyses were obtained using a GmbH VarioEL V3.00
automatic elemental analysis instrument. Elemental analyses for metals were detected
with an IRIS ER/ S-WP–1 ICP atomic emission spectrometer. IR spectra were
recorded on a VERTEX70 FT-IR spectrophotometer, with samples prepared as KBr
1
(500–4000 cm-1) pellets. H NMR spectra were determined with a German Bruker
AVANCE DRX-400 spectrometer. Melting points were obtained with the use of an
X4 microscopic melting point apparatus made by the Beijing Taike Instrument
Limited Company and were uncorrected. Fluorescent spectra were taken on a LS-55
fluorescence photometer. X-ray single crystal structure determinations were carried
out on a Bruker Smart Apex CCD diffractometer.
2.2. Synthesis of the ligand H2L
The main reaction steps involved in the synthesis of H2L are given in Scheme 1.
Scheme 1. Synthetic route to the Salamo-type ligand H2L
4,4ꢂ-Dinitro-2,2ꢂ-[1,2-ethylene-dioxybis(nitrilomethylidyne)]diphenol (H2L) was
prepared by a modification of the reported method [14]. An ethanol solution (10 mL)
of 5-nitrosalicylicaldehyde (341.6 mg, 2.01 mmol) was added to an ethanol solution
(10 mL) of 1,2-bis(aminooxy)ethane (93.4 mg, 1.00 mmol). The solution mixture was
stirred at 55 °C for 5h. After cooling to room temperature, the precipitate was filtered
and washed with ethanol and the ethanol/hexane (1:4). The product was dried under
vacuum to give colorless microcrystals. Yield: 298.69 mg (85.14%). Mp: 202-203 °C.
Anal. Calc. for C16H14N4O8 (%): C, 49.22; H, 3.92 N, 14.33. Found: C, 49.23; H, 3.90;
N, 14.36%. IR (KBr, cm-1): 3446 (w), 1629 (s), 1570 (s), 1483 (s), 1340 (s), 1272 (s),
1095 (s), 1047 (s), 1019 (s), 954 (m), 869 (s), 825 (m), 781 (s), 752 (s), 696 (m), 638
(m), 590 (s), 511 (m), 474 (m), 443 (m).
2.3. Synthesis of complexes 1, 2 and 3
3

The three solvent-induced Ni(II) complexes 1, 2 and 3 were obtained by the
reaction of the Salamo-type ligand H2L and Ni(OAc)2ꢃ4H2O in a 1:1 molar ratio in
absolute methanol, n-propanol and H2O solvents, respectively. Single crystals of
complexes 1, 2 and 3 suitable for X-ray diffraction analysis were grown using the
gaseous diffusion method.
2.3.1 Synthesis of complex 1
A solution of Ni(OAc)2ꢃ4H2O (2.82 mg, 0.01 mmol) in methanol (3 mL) was
added dropwise to a solution of H2L (3.52 mg, 0.01 mmol) in acetonitrile (3 mL) at
room temperature. The color of the resulting solution turned yellow immediately,
and stirring was continued for 1 h at room temperature. The solution was then filtered.
After three weeks, the solvent was partially evaporated and several green prismatic
single crystals suitable for X-ray crystallographic analysis were obtained. Yield: 2.50
mg (66.2%). Anal. Calc. for C38H38N8Ni3O22: C, 40.23; H, 3.36; N, 9.87; Ni, 15.33.
Found: C, 40.21; H, 3.35; N, 9.88; Ni, 15.34%. IR (KBr, cm-1): 3447 (w), 1604 (s),
1570 (s), 1483 (s), 1311 (s), 1256 (s), 1099 (s), 688 (m), 634 (m), 557 (s), 511 (m),
476 (m), 438 (m).
2.3.2 Synthesis of complex 2
A solution of Ni(OAc)2ꢃ4H2O (2.82 mg, 0.01 mmol) in n-propanol (3 mL) was
added dropwise to a solution of H2L (3.52 mg, 0.01 mmol) in acetonitrile (3 mL) at
room temperature. The color of the resulting solution turned yellow immediately,
and stirring was continued for 1 h at room temperature. The solution was then filtered
and the filtrate was allowed to stand at room temperature for about three weeks. The
solvent was partially evaporated and several green prismatic single crystals
suitable for X-ray crystallographic analysis were obtained. Yield: 2.49 mg (62.6%).
Anal. Calc. for C42H46N8Ni3O22: C, 42.33; H, 3.85; N, 9.41; Ni, 14.60. Found: C,
42.32; H, 3.86; N, 9.40; Ni, 14.61%. IR (KBr, cm-1): 3463 (w), 1602 (s), 1560 (s),
4

1479 (s), 1307 (s), 1253 (s), 1107 (s), 692 (m), 646 (m), 567 (s), 522 (m), 477 (m),
439 (m).
2.3.3 Synthesis of complex 3
A solution of Ni(OAc)2ꢃ4H2O (2.82 mg, 0.01 mmol) in 2-propanol (3 mL) was
added dropwise to a solution of H2L (3.52 mg, 0.01 mmol) in acetonitrile (3 mL) at
room temperature. The color of the resulting solution turned yellow immediately,
and stirring was continued for 1 h at room temperature. The solution mixture was
filtered and the filtrate was allowed to stand at room temperature for about three
weeks. The solvent was partially evaporated and several green prismatic single
crystals suitable for X-ray crystallographic analysis were obtained. Yield: 2.24 mg
(60.7%). Anal. Calc. for C36H34N8Ni3O22: C, 39.07; H, 3.10; N, 10.12; Ni, 15.91.
Found: C, 39.06; H, 3.07; N, 10.13; Ni, 15.73%. IR (KBr, cm-1): 3456 (w), 1635(w),
1606 (s), 1568 (s), 1483 (s), 1311 (s), 1253 (s), 1107 (s), 688 (m), 632 (m), 582 (s),
534 (m), 507 (m), 472 (m), 434 (m).
2.4 X-ray crystallography of complexes 1, 2 and 3
The crystal and structure refinement data for complexes 1, 2 and 3 are given in
Table 1. The single crystals of complexes 1, 2 and 3, with the approximate
dimensions of 0.23 × 0.21 × 0.16, 0.31 × 0.24 × 0.23 and 0.25 × 0.23 × 0.21 mm,
were placed on a Bruker Smart 1000 CCD area detector. The reflections were
collected using graphite monochromated MoKꢄ radiation (ꢅ = 0.71073 Å) at 298(2) K.
The structures were solved using the program SHELXL-97 and Fourier difference
techniques, and refined by the full-matrix least-squares method on F2. All hydrogen
atoms were added in calculated positions. The non-hydrogen atoms were refined
anisotropically. All hydrogen atoms were added theoretically.
Table 1 Crystal data and structure refinement for complexes 1, 2 and 3
3. Results and discussion
5

3.1. IR spectra analyses
The FT-IR spectra of H2L and its corresponding Ni(II) complexes 1, 2 and 3
exhibit various bands in the 4000-400 cm-1 region. It is obvious that the ν(O–H)
absorption band is near 3446 cm-1 in the free ligand H2L. The free ligand H2L exhibits
a characteristic C=N stretching band at 1629 cm-1, and for complexes 1, 2 and 3 the
corresponding absorption bands appear at 1604, 1602 and 1606 cm-1, indicating
coordination of the Ni(II) atoms with the oxime nitrogen atoms [15c]. The C=N
stretching frequencies are shifted to lower frequencies by ca. 23-25 cm-1 upon
complexation, indicating a decrease in the C=N bond order due to the coordinated
bonds of the divalent metal atoms with the oxime nitrogen lone pair. The observed
bands in the range 1479-1483 cm-1 are attributed to the aromatic C=C skeleton
vibrations [15].
The Ar-O stretching frequency of H2L appears as a strong band at 1272 cm-1, as
reported for similar Salen-type ligands [1,2,14], while Ar-O stretching frequencies of
complexes 1, 2 and 3 were observed at 1256, 1253 and 1267 cm-1, respectively. The
Ar-O stretching frequencies are shifted, indicating that Ni-O bonds are formed
between the Ni(II) atoms and the oxygen atoms of the phenolic groups. In addition,
O-H stretching bands can be found at 3447, 3463 and 3456 cm-1 in complexes 1, 2
and 3, respectively, which indicates the presence of methanol, n-propanol and H2O
molecules, and the expected absorptions in complex 3 were observed at 1635 and ca.
534 cm-1, respectively. The two bands should be assigned to the bending and wagging
modes of water molecules, providing evidence for the existence of coordinated water
molecules [14e,14f,15c-15f].
The far-infrared spectra of complexes 1, 2 and 3 were also obtained in the region
500-100 cm-1 in order to identify frequencies due to the Ni-O and Ni-N bonds. The
ꢆ(Ni-O) and ꢆ(Ni-N) vibration absorption bands are observed at 476 and 438 cm-1 for
complex 1, 477 and 439 cm-1 for complex 2 and at 472 and 434 cm-1 for complex 3,
respectively. These assignments are consistent with the literature frequency values
6

[15b-15g] and similar bands are not present in the spectrum of the free ligand.
3.2. UV-vis absorption spectral analyses
The UV-vis absorption spectra of the free ligand H2L and its corresponding
trinuclear Ni(II) complexes 1, 2 and 3 in the DMF solutions (5.0×10-5 mol/L) at 298 K
are shown in Fig. 1. The UV–Vis spectrum of the free ligand H2L exhibits two
absorption peaks at ca. 375 and 448 nm, respectively. The former absorption peak at
*
375 nm can be assigned to the intra-ligand π–π transition of the C=N bonds [16] and
the latter one around 448 nm can be ascribed to the quinoid form of Salen-type
compounds, which is sometimes absent in the corresponding Salen-type analogues
[8a]. Compared with the free ligand H2L, the weak absorption band at 375 nm
disappears from the UV–Vis spectra of complexes 1, 2 and 3, which indicates that the
oxime nitrogen atoms are involved in coordination to the Ni(II) atoms [16]. Moreover,
new and strong absorption bands are observed at 400, 356 and 356 nm for complexes
1, 2 and 3, respectively, which are assigned to L→M charge-transfer (LMCT)
transitions, characteristic of transition metal complexes with an N2O2 coordination
sphere [17]. The differences observed in the charge-transfer (LMCT) transition peaks
of complexes 1, 2 and 3 may be caused by displacement of the coordinated solvent.
Fig 1 UV-vis absorption spectra of the ligand H2L and its complexes 1, 2 and 3
3.3 Fluorescence properties analyses
The fluorescent properties of H2L and its corresponding complexes 1, 2 and 3
were investigated in dilute DMF solutions (5.0×10-5 mol/L) at room temperature. The
ligand H2L does not exhibit an emission peak upon excitation at 375 nm, while
complexes 1, 2 and 3 show intense photoluminescence with maximum emissions at ca.
319, 282 and 318 nm upon excitation at 375 nm, respectively (Fig. 2). Compared with
the ligand H2L, strong fluorescence intensities of complexes 1, 2 and 3 are observed,
indicating that the fluorescence characteristic has been influenced by the introduction
7

of the Ni(II) atoms. Fluorescence enhancement via complexation is of high interest as
its application is widely used in photochemical processes. The quench in fluorescence
of the free ligand H2L could be the result of the occurrence of a photoinduced electron
transfer process owing to the presence of a lone pair of electrons on the nitrogen
atoms. The process is prevented by the complexation of the free ligand H2L with the
Ni(II) atoms. Therefore, the intensities in the fluorescence can be greatly enhanced
through the coordination of Ni(II) atoms. Moreover, the chelation of the ligand H2L
with the Ni(II) atoms increases the rigidity of the ligand H2L and thus minimizes
energy loss through vibrational motions, which may increase the efficiency of the
emission.
Fig 2 Emission spectra of the ligand H2L and its complexes 1, 2 and 3
3.4. Description of the crystal structures
Selected bond lengths and bond angles for complexes 1, 2 and 3 are presented in
Tables 2, 3 and 4, respectively. A list of hydrogen bonding interactions in complexes
1, 2 and 3 are given in Table 5.
3.4.1. Structure of complex 1
The X-ray crystal structure analysis shows that complex 1 consists of three Ni(II)
atoms, two completely deprotonated (L)2- units, two µ-acetate ions and two
coordinated methanol molecules (Fig. 3). The terminal Ni(II) atom (Ni2 or Ni2#1) is
hexa-coordinated by two oxime nitrogen (N2 and N3) and two phenolic oxygen (O1
and O8) atoms of the deprotonated Salamo-type (L)2- unit, one oxygen atom (O10)
from the coordinated µ-acetate ion and one oxygen atom (O9) from the coordinated
methanol molecule. The coordination geometry around the terminal Ni(II) atom is
found to be a slightly distorted octahedron. The two phenolic oxygen atoms (O1 and
O8) and two oxime nitrogen atoms (N2 and N3) are in mutually cis-positions. The
primary Ni-N and Ni-O distances are in the normal ranges (Ni2-N2 = 2.078(2),
Ni2-N3 = 2.031(2), Ni2-O1 = 2.073(2), Ni2-O8 = 2.027(2), Ni2-O9 = 2.140(2) and
8

Ni2-O10 = 2.071(2) Å) (Table 2). The bond length between the Ni(II) atom and the
apical oxygen atom (O9) is 2.140(2) Å, which is obviously longer than the distances
between the Ni(II) atom and the basal oxygen and nitrogen atoms. This significant
elongation has been observed previously in Ni(II) complexes with Salamo-type
ligands [14f,15c].
Table 2 Selected bond distances (Å) and angles (°) for complex 1.
Fig. 3 (a) Molecule structure and atom numbering scheme of complex 1 (hydrogen
atoms are omitted for clarity). (b) Coordination polyhedra for the Ni(II) atoms of
complex 1
The coordination geometry of the central Ni(II) atom (Ni1) deviates slightly from
ideal octahedral. The central Ni1 atom (Ni1) has an O2O2 donor set from four
µ-phenolic oxygen atoms (O1, O8, O1#1 and O8#1) of two completely deprotonated
(L)2- units and each of the µ-acetate ions bridge the central Ni1 and terminal Ni2 (or
Ni2#1) atoms in the syn-syn bridging mode; as a result the central Ni1 atom finally has
an O2O2O2 coordination environment. The primary Ni-O distances are in the normal
ranges (Ni1-O1 = 2.073(2), Ni1-O1#1 = 2.073(2), Ni1-O8 = 2.099(2), Ni1-O8#1
2.099(2), Ni1-O11 = 2.018(2) and Ni1-O11#1 = 2.018(2) Å) (Table 2).
=
In the crystal structure of complex 1, the structure is connected by four pairs of
intramolecular C–H⋅⋅⋅O hydrogen bonding interactions (Table 5 and Fig. 4), which
play a vital role in constructing and stabilizing the complex 1 molecules. As shown in
the Fig. 5, the neighboring complex molecules are further linked into an infinite
two-dimensional supramolecular network by three pairs of intermolecular hydrogen
bonds (O9–H9C⋅⋅⋅O3, C5–H5⋅⋅⋅O7 and C7–H7⋅⋅⋅O7) [18].
Fig. 4 Intramolecular hydrogen bonding interactions of complex 1
Fig. 5 Part of the infinite 2D supramolecular network of complex 1
3.4.2. Structures of complexes 2 and 3
9

The X-ray crystal structure analyses of complexes 2 and 3 reveal that they have
the same individual trinuclear neutral molecular unit [{(Ni(L))2(solvent)2}Ni] (the
solvents are n-propanol and H2O in complexes 2 and 3, respectively), as shown in
Figs. 6 and 9, respectively, while the different solvents observed lead to the formation
of the typical solvent-induced Ni(II) complexes [19].
Fig. 6 Molecule structure and atom numbering scheme of complex 2 (hydrogen atoms
are omitted for clarity). (b) Coordination polyhedra for the Ni(II) atoms of complex 2
Table 3 Selected bond distances (Å) and angles (°) for complex 2.
Complex 2 consists of a linear array of three Ni(II) atoms coupled by both double
µ-phenoxo of (L)2- units and µ-acateate anions in the syn-syn bridging mode. The
terminal Ni(II) atom (Ni1 or Ni1#1) lies in a hexa-coordinated environment and adopts
a distorted octahedral geometry, where the inner N2O2 coordinated environment of the
completely pentadentate (L)2- units comprise the basal plane and one oxygen atom
(O10) from the µ-acetate ion and one oxygen atom (O12) from the coordinated
solvent molecule occupy the apical positions. The Ni-N and Ni-O primary distances
are in the normal ranges (Ni1-N2 = 2.085(4), Ni1-N3 = 2.084(4), Ni1-O1 = 2.037(3),
Ni1-O6 = 2.035(3), Ni1-O10 = 2.032(3) and Ni1-O12 = 2.116(3) Å) (Table 3). The
bond length between the Ni(II) atom and the apical oxygen atom (O12) is 2.116(3) Å,
which is obviously longer than the distances between the Ni(II) atom and the basal
oxygen and nitrogen atoms. In addition, the central Ni2 atom is located in a
hexa-coordinated environment and adopts an ideal octahedral geometry. The Ni-O
primary distances are in the normal ranges (Ni2-O1 = 2.073(3), Ni1-O1#1 = 2.073(3),
Ni2-O6 = 2.080(3), Ni2-O6#1 = 2.080(3), Ni2-O9 = 2.071(3) and Ni1-O9#1 = 2.071(3)
Å). The crystal structure of complex 3 is very similar to that of complex 2.
Fig.7 Intramolecular hydrogen bonding interactions of complex 2
Fig. 8 Part of the infinite 3D supramolecular structure showing the hydrogen bonding
interactions of complex 2
10

Table 4 Selected bond distances (Å) and angles (°) for complex 3.
Fig. 9 Molecule structure and atom numbering scheme of complex 3 (hydrogen atoms
are omitted for clarity). (b) Coordination polyhedra for the Ni(II) atoms of complex 3
The intramolecular and intermolecular hydrogen bonding interactions of complex
2 are given in Figs. 7 and 8, and those of complex 3 are given in Figs. 10 and 11,
respectively. The monomeric octahedral unit and the polymeric representation of the
structure are presented in Figs. 8 and 11, respectively. It is noteworthy that the
coordinated solvent molecules (n-propanol or H2O) of complexes 2 and 3 are different
from complex 1, such solvent effects can lead to different supramolecular interactions.
In complexes 2 and 3, the neighboring complex molecules are linked into infinite
three-dimensional supramolecular structures by intermolecular hydrogen bonding
interactions (In complex 2: O12–H12B⋅⋅⋅O7, C20–H20B⋅⋅⋅O3 and C3–H3⋅⋅⋅O8; in
complex 3: C9–H9A⋅⋅⋅O8 and C10–H10A⋅⋅⋅O7) (Tables 4 and 5) [20].
Table 5 Hydrogen bonding interactions [Å, °] for complexes 1, 2 and 3.
Fig.10 Intramolecular hydrogen bonding interactions of complex 3.
Fig. 11 Part of the infinite 3D supramolecular structure showing the hydrogen
bonding interactions of complex 3.
4. Conclusion
In complexes 1, 2 and 3, the ligand H2L is completely deprotonated as a
tetradentate (L)2- dianion and there are two solvent molecules coordinating to the two
terminal Ni(II) atoms. These complexes have elongated octahedral coordination
environments with an unusually long bond from the hexa-coordinated Ni(II) centers
to the oxygen atoms of the apical coordinated solvent molecules for the terminal Ni(II)
atoms, and distorted octahedral geometries for the central Ni(II) atom. These
complexes exhibit abundant hydrogen bonding interactions in the solid state. UV-vis
spectra clearly indicate the structures of the three complexes are different from the
11

ligand (H2L). X-ray crystal structures reveal that the structures of complexes 1, 2 and
3 are very similar except for the difference of the coordinated solvent molecules.
Interestingly, the existence of solvent effects leads to slight differences in the crystal
and supramolecular structures of complexes 1, 2 and 3.
Supplementary data
CCDC 1522520-1522522 contain the supplementary crystallographic data for 1, 2 and
3. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
Acknowledgements
This work was supported by the National Natural Science Foundation of China
(21361015), which is gratefully acknowledged.
12

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14

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16

Table 1 Crystal data and structure refinement for complexes 1, 2 and 3
Compound
complex 1
complex 2
complex 3
C36H34N8Ni3O22
1106.84
293
0.71073
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
ꢄ (º)
ꢇ (º)
C38H38N8Ni3O22
1134.89
294
0.71073
triclinic
P -1
C42H46N8Ni3O22
1191.00
293
0.71073
monoclinic
monoclinic
C (2)/c
P 2(1)/c
23.508(5)
11.4156(18)
23.490(5)
90
112.10(2)
90
5840.5(19)
4
1.259
1.028
2264.0
0.23 × 0.21 × 0.16
-28 ꢊ h ꢊ 28
9.8878(6)
10.7482(5)
13.4889(6)
73.631(4)
69.603(5)
73.914(5)
1263.44(11)
1
0.7265(5)
14.8589(5)
17.5199(11)
90
99.911(5)
90
2750.7(2)
2
1.438
1.097
1228.0
ꢈ (º)
Volume (Å3)
Z
Density calculated (Mg/m3)
1.492
Absorption coefficient (mm–1) 1.191
F (000)
Crystal size (mm)
Limiting indices
582.0
0.25 × 0.23 × 0.21 0.31 × 0.24 × 0.23
-13 ꢊ h ꢊ 13
-13 ꢊ k ꢊ 10
-17 ꢊ l ꢊ 18
0.957, 1.000
4949
327 / 0 / 3
1.035
-13 ꢊ h ꢊ 11
-17 ꢊ k ꢊ 18
-13 ꢊ l ꢊ 21
0.736, 0.777
5414
345 / 0 / 3
1.022
-8 ꢊ k ꢊ 14，
-28 ꢊ l ꢊ 25
0.789, 0.848
5716
315 / 0 / 3
0.879
Max.&. min. transmission
Independent reflections
Data / restraints / parameters
GOF on F2
R1, wR2 [I >2ꢉ(I)]
0.0419, 0.1126
0.0579, 0.1610
0.0630, 0.1553
17

Table 2 Selected bond distances (Å) and angles (°) for complex 1.
bond
Dis. (Å)
2.073(2)
2.073(2)
2.099(2)
2.099(2)
bond
Dis. (Å)
2.018(2)
2.018(2)
2.034(2)
2.027(2)
bond
Dis. (Å)
2.140(2)
2.031(2)
2.078(2)
2.085(3)
Ni1-O1
Ni1-O1#1
Ni1-O8
Ni1-O8#1
Ni1-O11
Ni1-O11#1
Ni2-O1
Ni2-O8
Ni2-O9
Ni2-O10
Ni2-N2
Ni2-N3
bond
angles (°)
78.09(7)
bond
angles (°)
87.95(8)
92.05(8)
180
bond
angles (°)
180
O1-Ni1-O8
O1-Ni1-O8#1
O8-Ni1-O1#1
O11-Ni1-O1#1 92.05(8)
O1#1-Ni1-O8#1 78.09(7)
O1-Ni1-O11
O1-Ni1-O11#1
O8-Ni1-O8#1
O11-Ni1-O8#1
O1-Ni1-O1#1
O8-Ni1-O11
O8-Ni1-O11#1
O11-Ni1-O11#1 180
O8#1-Ni1-O11#1 90.06(8)
101.91(7)
90.06(8)
101.91(7)
89.94(8)
89.94(8)
O1#1-Ni1-O11#1 87.95(8)
O1-Ni2-O8
O1-Ni2-N2
O8-Ni2-O10
O9-Ni2-O10
O10-Ni2-N2
Ni1-O1-Ni2
Ni1-O8-C12
80.66(8)
86.05(1)
90.03(9)
175.96(9)
91.66(1)
97.37(8)
132.72(2)
O1-Ni2-O9
O1-Ni2-N3
O8-Ni2-N2
O9-Ni2-N2
O10-Ni2-N3
Ni1-O1-C1
N3-O5-C9
89.17(8)
166.75(9)
166.69(1)
88.01(1)
91.99(1)
133.09(2)
112.9(3)
128.64(2)
131.5(2)
128.7(2)
O1-Ni2-O10
O8-Ni2-O9
O8-Ni2-N3
O9-Ni2-N3
N2-Ni2-N3
Ni2-O1-C1
Ni1-O8-Ni2
Ni2-O9-C17
O2-N1-O3
Ni2-N2-O4
94.83(9)
91.21(8)
88.00(9)
84.21(1)
105.12(1)
125.09(2)
96.75(8)
125.7(2)
122.4(3)
127.2(2)
Ni2-O10-C18 125.5(2)
Ni2-O8-C12
Ni1-O11-C18
Ni2-N3-O5
Ni2-N2-C7
123.5(2)
123.6(2)
Ni2-N3-C10
Symmetry transformations used to generate equivalent atoms: #1 1-x, -y, 1-z.
18

Table 3 Selected bond distances (Å) and angles (°) for complex 2.
bond
Dis. (Å)
bond
Dis. (Å)
bond
Dis. (Å)
Ni1-O1
2.037(3)
2.035(3)
2.032(3)
2.116(3)
angles (°)
89.78(1)
87.00(1)
167.38(1)
80.34(1)
89.54(1)
166.92(1)
87.41(1)
92.96(1)
91.67(1)
177.16(1)
92.27(2)
90.41(1)
87.11(2)
87.08(1)
105.03(1)
Ni1-N2
2.085(4)
2.084(4)
2.073(3)
2.073(3)
angles (°)
180.000(1)
78.48(1)
101.52(1)
78.48(1)
101.52(1)
180.0
Ni2-O6
2.080(3)
2.080(3)
2.017(3)
2.017(3)
angles (°)
97.40(1)
125.7(3)
132.2(3)
97.25(1)
126.5(2)
132.5(3)
132.5(3)
125.2(3)
118.7(1)
131.1(3)
110.0(1)
127.7(3)
123.7(3)
128.1(3)
123.2(3)
Ni1-O6
Ni1-N3
Ni2-O6#2
Ni1-O10
Ni2-O1
Ni2-O1#2
Ni2-O9
Ni2-O9#2
Ni1-O12
bond
bond
bond
O1-Ni1-O12
O1-Ni1-N2
O1-Ni1-N3
O6-Ni1-O1
O6-Ni1-O12
O6-Ni1-N2
O6-Ni1-N3
O10-Ni1-O1
O10-Ni1-O6
O10-Ni1-O12
O10-Ni1-N2
O10-Ni1-N3
N2-Ni1-O12
N3-Ni1-O12
N3-Ni1-N2
O1-Ni2-O1#2
O1#2-Ni2-O6#2
O1-Ni2-O6#2
O1-Ni2-O6
O1#2-Ni2-O6
O6#2-Ni2-O6
O9#2-Ni2-O1#2
O9-Ni2-O1
O9#2-Ni2-O1
O9-Ni2-O1
O9-Ni2-O6#2
O9#2-Ni2-O6#2
O9-Ni2-O6
O9#2-Ni2-O6
O9-Ni2-O9#2
Ni1-O1-Ni2
C1-O1-Ni1
C1-O1-Ni2
Ni1-O6-Ni2
C16-O6-Ni1
C16-O6-Ni2
C21-O9-Ni2
C21-O10-Ni1
Ni1-O12-H12
C18-O12-Ni1
C18-O12-H12
O4-N2-Ni1
C7-N2-Ni1
O5-N3-Ni1
C10-N3-Ni1
87.90(1)
87.90(1)
92.10(1)
92.10(1)
90.89(1)
89.11(1)
89.11(1)
90.89(1)
180.0
Symmetry transformations used to generate equivalent atoms: #2 -x, 1-y, 1-z.
19

Table 4 Selected bond distances (Å) and angles (°) for complex 3.
bond
Dis. (Å)
2.011(4)
2.041(3)
2.047(3)
2.079(4)
angles (°)
bond
Dis. (Å)
2.088(4)
2.107(4)
2.065(3)
2.065(3)
angles (°)
bond
Dis. (Å)
2.072(4)
2.072(4)
2.084(3)
2.084(3)
angles (°)
Ni2-O11
Ni2-O1
Ni2-O6
Ni2-O10
bond
Ni2-N3
Ni2-N2
Ni1-O6
Ni1-O6#3
bond
Ni1-O9
Ni1-O9#3
Ni1-O1
Ni1-O1#3
bond
O1-Ni1-O6
77.88(13)
O1-Ni1-O9
90.54(14)
89.46(14)
180
O1-Ni1-O1#3
O6-Ni1-O9
O6-Ni1-O9#3
O9-Ni1-O9#3
O6#3-Ni1-O9#3
O1-Ni2-O11
O6-Ni2-O10
O6-Ni2-N3
O10-Ni2-N3
N2-Ni2-N3
Ni2-O1-C1
180
O1-Ni1 -O6#3
O6-Ni1-O1#3
O9-Ni1-O1#3
O1#3-Ni1-O6#3
O1-Ni2 -O6
O1-Ni2 -N2
O6-Ni2 -O11
O10-Ni2-O11
O11-Ni2-N2
Ni1-O1-Ni2
Ni2-N3-C10
Ni1-O6-C16
Ni2-O11-C17#3
102.12(13) O1-Ni1-O9#3
102.12(13) O6-Ni1-O6#3
90.67(14)
89.33(14)
180
89.46(14)
77.88(13)
79.25(13)
86.65(15)
91.18(15)
O9-Ni1-O6#3
O1#3-Ni1-O9#3
O1-Ni2 -O10
O1-Ni2 -N3
O6-Ni2 -N2
89.33(14)
90.54(14)
88.33(15)
165.49(16)
165.76(15)
88.89(17)
91.23(18)
134.5(3)
128.2(3)
128.1(3)
127.5(3)
90.67(14)
94.09(16)
92.62(14)
87.17(15)
87.22(17)
107.05(17)
126.5(3)
97.88(13)
130.2(4)
124.3(4)
175.82(14) O10 -Ni2 -N2
87.85(17)
97.49(13)
124.6(4)
132.7(3)
128.4(4)
O11 -Ni2 -N3
Ni1 -O1-C1
Ni2 -O6-C16
Ni2 -N2-O4
Ni2 -N3-O5
Ni1-O6-Ni2
Ni1-O9-C17
Ni2-N2-C7
Symmetry transformations used to generate equivalent atoms: #3 1-x, 1-y, 1-z.
20

Table 5 Hydrogen bonding interactions [Å,°] for complexes 1, 2 and 3
D-H…A
d(D-H) d(H…A) d(D…A)
Symmetry code
∠D-H…A
Complex 1
0.863
0.93
0.97
0.93
0.96
0.93
0.93
2.027
2.55
2.36
2.56
2.48
2.58
2.58
2.834(3) 155
2-x,-y,-z
1-x,-y, 1-z
O9-H9⋅⋅⋅O3
C2-H2⋅⋅⋅O11
C8-H8A⋅⋅⋅O10
C13-H13⋅⋅⋅O1
C17-H17B⋅⋅⋅O11
C7-H7⋅⋅⋅O7
3.169(3) 125
3.204(4) 145
3.299(4) 136
3.377(5) 156
3.421(4) 151
3.387(4) 156
1-x,-y,1-z
1-x,-y,1-z
C5-H5⋅⋅⋅O7
Complex 2
O12-H12…O7
C2-H2…O9
C9-H9B…O10
C12-H12A…O7 0.93
C15-H15…O9
C3-H3…O8
C18-H18A…O9 0.97
C20-H20B…O3 0.96
Complex 3
0.86
0.93
0.97
1.95
2.53
2.47
2.39
2.57
2.56
2.48
2.58
2.802(5) 177
3.153(5) 124
3.293(7) 142
2.708(6) 100
3.165(5) 122
3.384(7) 154
3.427(6) 166
3.508(7) 163
1-x,-1/2+y,3/2-z
-x,1-y,1-z
0.93
0.93
-x,1-y,1-z
-x,-1/2+y,3/2-z
-x,1-y,1-z
-x,1/2+y,3/2-z
O10-H10A…O7 0.90
2.00
2.56
2.37
2.39
2.58
2.823(6) 153
3.228(6) 129
3.186(7) 142
3.221(9) 143
3.217(6) 126
1/2-x,-1/2+y,1/2-z
x,-1+y,z
C2-H2…O9
0.93
0.97
0.97
0.93
C8-H8B…O11
C9-H9A…O8
C15-H15…O9
21

O
N
O
N
CHO
OH
CH3CH2OH
55
NO2
OH
HO
NO2
O2N
+
H2N
O
O
NH2
Scheme 1
22

1.5
1.0
0.5
0.0
H2L
Complex 1
Complex 2
Complex 3
350
400
450
500
Wavelength (nm)
Fig. 1
23

Fig. 2
24

Fig. 3
25

Fig. 4
26

Fig. 5
27

Fig. 6
28

Fig. 7
29