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Article

Solvent-Induced Unsymmetric Salamo-Like Trinuclear NiII Complexes: Syntheses, Crystal Structures, Fluorescent and Magnetic Properties

by
Jing Li
1,
Hong-Jia Zhang
1,
Jian Chang
1,
Hao-Ran Jia
1,
Yin-Xia Sun
1,* and
Yong-Qing Huang
2
1
School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
2
State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China
*
Author to whom correspondence should be addressed.
Crystals 2018, 8(4), 176; https://doi.org/10.3390/cryst8040176
Submission received: 26 March 2018 / Revised: 14 April 2018 / Accepted: 16 April 2018 / Published: 18 April 2018
(This article belongs to the Section Crystal Engineering)
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Abstract

:
Solvent-induced trinuclear NiII complexes, [{Ni(L)(MeOH)}2(OAc)2Ni]·2MeOH (1), [{Ni(L)(EtOH)}2(OAc)2Ni]·2H2O (2), [{Ni(L)(n-PrOH)}2(OAc)2Ni]·2H2O (3) and [{Ni(L)(i-PrOH)}2(OAc)2Ni] (4), have been prepared with an unsymmetric Salamo-like ligand H2L, and characterized via X-ray crystallography, FT-IR, UV-Vis and fluorescence spectra. In complexes 1, 2, 3 and 4, there are two ligand (L)2− moieties, two acetato ligands, two coordinated methanol, ethanol, n-propanol or i-propanol molecules, respectively, as well as other crystallizing solvent molecules. Two acetato ligands coordinated to the three NiII ions via usual Ni-O-C-O-Ni bridges, and four µ-phenoxo oxygen atoms coming from two [NiL(solvent)] units coordinate to the central NiII ions. Although different solvents are induced in the complexes, all the NiII ions are six-coordinated and adopt geometries of distorted octahedron. Magnetic measurements were performed on complex 2, an intramolecular antiferromagnetic interaction was observed between NiII ions and a simulation of the experimental data gives J = −2.96 cm−1 and g = 2.30.

Graphical Abstract

1. Introduction

Metal complexes bearing Salen-like ligands or their derivatives are now a significant research subject [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], and could be of ubiquitous use in biological systems [16,17,18,19,20,21,22,23,24], fluorescent sensors [25,26,27,28,29,30,31,32,33,34,35,36,37], magnetic properties [38,39,40,41,42], optical materials [43,44,45,46,47,48,49,50,51] and building blocks for supramolecular features [52,53,54,55,56,57,58,59,60,61,62]. Though a number of advances have been obtained in the researches of Salen-like NiII complexes [63,64,65,66,67,68,69], there might be novel applications for such a group of unique compounds. Compared with the symmetric Salen-like ligands, the unsymmetric Salen-like ligands are uncommon because electronic and steric effects of unsymmetric configurations with Salen-like ligands or their derivatives would provide more structural changes and coordination compounds [70,71,72,73,74,75] and would be expected to acquire new features [76]. In addition, the construction of complexes is often affected by many subtle factors such as ligands, metal ions, solvents, pH values and temperatures [42,77,78,79,80]. Among them (except for ligands), the solvents are perhaps also clear and direct factors [81,82,83]. In order to research the structural features, spectral characteristics, magnetic properties and investigated solvent effects of the transition metal complexes with unsymmetric Salen-like ligands, we herein study four supramolecular NiII complexes 1, 2, 3 and 4 with a new unsymmetric Salamo-like ligand.

2. Experimental

2.1. Material and General Methods

All chemicals were used without further purification, and were of analytical reagent grades. C, H, and N analyses were acquired by an Elementar GmbH VarioEL V3.00 automatic elemental analysis instrument (Hanau, Germany). Elemental analyses for NiII ions were detected by an IRIS ER/S-WP–1 ICP atomic emission spectrometer (Elementar, Berlin, Germany). Keep accounts of the IR spectra data using the VERTEX70 FT-IR spectrophotometer (Bruker, Karlsruhe, Germany), and the samples were prepared as KBr (500–4000 cm−1) pellets. 1H NMR spectra were recorded using a Mercury-400BB spectrometer (Varian, Palo Alto, CA, USA) at 400 MHz. Melting points were measured via an X4 microscopic melting point apparatus produced by Beijing Taike Instrument Limited Company (Beijing, China) and were uncorrected. Fluorescent spectra were performed on a LS-55 fluorescence photometer (Perkin-Elmer, Norwalk, America). X-ray single crystal structure determinations were performed on a Bruker Smart Apex CCD diffractometer (Karlsruhe, Germany). Magnetic susceptibility data were measured on powdered samples of complex 2 using a Quantum Design model MPMS XL7 SQUID magnetometer (Quantum Design, San Diego, CA, America). Magnetic susceptibility measurements were performed at 1000 Oe in the 2–300 K temperature range.

2.2. Synthesis of H2L

1,2-Bis(aminooxy)ethane and 4-methyoxy-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol (H2L) were prepared on the basis of an similar procedure [84,85,86,87,88]. Synthetic route to the ligand is depicted in Scheme 1. Yield: 48%. M.p.: 69–71 °C. 1H NMR (400 MHz, CDCl3): δ: 3.81 (s, 3H, CH3), 4.44 (m, 4H, CH2), 6.46~6.49 (m, 2H, ArH), 6.89~6.92 (d, J = 12 Hz, 1H, ArH), 6.97~6.99 (d, J = 8 Hz, 1H, ArH), 7.04~7.06 (d, J = 8 Hz, 1H, ArH), 7.15~7.17 (d, J = 8 Hz, 1H, ArH), 8.18 (s, 1H, CH=N), 8.24 (s, 1H, CH=N), 9.75 (s, 1H, OH), 9.92 (s, 1H, OH). Anal. Calcd. for C17H18N2O5 (%): C, 61.81; H, 5.49; N, 8.48; Found (%): C, 62.05; H, 5.52; N, 8.38.

2.3. Syntheses of NiII Complexes 1, 2, 3 and 4

Complex 1: A pale-green methanol solution (2 mL) of NiII acetate tetrahydrates (3.81 mg, 0.015 mmol) was added dropwise to a colorless acetonitrile solution (2 mL) of H2L (3.23 mg, 0.01 mmol). The solution color was pale-green still. The mixed solution was filtered, and the filtrate was placed at room temperature to slowly evaporate; about two weeks later, light green block crystals suitable for single crystal X-ray diffraction were gained. Anal. Calcd. for C42H54Ni3N4O18 (%): C, 46.75; H, 5.04; N, 5.19; Ni, 16.32. Found (%): C, 46.97; H, 5.16; N, 5.02; Ni, 16.13.
Complex 2: Complex 2 was prepared by a method similar to that of complex 1 except substituting methanol with ethanol and acetonitrile with acetone. The color of the mixture continued to be pale-green but cooled off immediately and clear light green, block-like crystals were gained after two weeks following the solvent was slowly evaporated. Anal. Calcd. for C40H46Ni3N4O20 (%): C, 44.53; H, 4.30; N, 5.19; Ni, 16.32. Found (%): C, 44.68; H, 4.45; N, 5.01; Ni, 16.15.
Complex 3: Complex 3 was prepared by changing methanol to n-propanol and acetonitrile to dichloromethane. The color of the mixture continued to be pale-green but cooled off immediately and clear light green, block-like crystals were gained after one week. Anal. Calcd. for C44H58Ni3N4O18 (%): C, 47.74; H, 5.28; N, 5.06; Ni, 15.91. Found (%): C, 47.89; H, 5.35; N, 4.92; Ni, 16.07.
Complex 4: Complex 4 was prepared by changing methanol to isopropanol and acetonitrile to dichloromethane. The color of the mixture continued to be pale-green but cooled off immediately and clear light green, block-like crystals were gained after ten days. Anal. Calcd. for C44H50Ni3N4O16 (%): C, 49.53; H, 4.72; N, 5.25; Ni, 16.50. Found (%): C, 49.75; H, 4.88; N, 5.13; Ni, 16.26.

2.4. X-ray Crystallography

Because of the similar structures of the complexes 1–4, only the details of the data collection and refinements of NiII complex 1 are presented in Table 1 (That of 2, 3 and 4 are listed in Table S1). A single crystal of NiII complexes 1, 2, 3 and 4 was put on a Bruker Smart 1000 CCD area detector. The reflections were collected by a graphite monochromated Mo Ka radiation (λ = 0.71073 Å) at 294K for NiII complexes 1, 2 and 4, and that of NiII complex 3 was collected by a graphite monochromated Cu Ka radiation (λ = 1.54184 Å) at 293 K. The structures were solved by the program SHELXL-97 and Fourier difference techniques, and were 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. Supplementary crystallographic data for this paper have been deposited at Cambridge Crystallographic Data Centre (1480197, 1480194, 1480196 and 1480195 for complexes 1, 2, 3 and 4) and can be gained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html.

3. Results and Discussion

H2L is white powder, stable in air and soluble in some organic solvents such as ethanol, methanol, CH2Cl2, CHCl3, acetonitrile, acetone, DMF and THF, but insoluble in Et2O, n-hexane. NiII complexes 1, 2, 3 and 4 are all soluble in CHCl3 and DMF, but not soluble in n-hexane, Et2O, acetone and acetonitrile.

3.1. Crystal Structure Descriptions of NiII Complexes 1, 2, 3 and 4

Selected bond lengths and angles for NiII complexes 1, 2, 3 and 4 are listed in Table 2. Crystal structures and atom numberings of complexes 1, 2, 3 and 4 are depicted in Figure 1, Figure 2, Figure 3 and Figure 4, respectively.
X-ray crystal structure analyses revealed that the NiII complexes 1, 2, 3 and 4 take on similar crystal structures, which all are symmetric trinuclear structures. The crystals of NiII complexes are solved as tetragonal space group I41/a (1), triclinic space group P-1 (2), monoclinic space group C2/c (3) and monoclinic space group P21/n (4), respectively. All the NiII complexes consist of three NiII ions, two (L)2− moieties, two µ-acetato ligands, and two coordinated methanol, ethanol, n-propanol or i-propanol molecules in NiII complexes 1, 2, 3 and 4, respectively, as well as crystalizing solvent molecules (two MeOH in 1 and two H2O in 2 and 3, respectively).
In NiII complexes 1, 2, 3 and 4, each of the terminal Ni1 ions sat in the cis-N2O2 cavity (N1, N2, O1 and O4) of the deprotonated (L)2− moieties, and carboxylate O7 atom from the µ-acetato bridge and O6 atom from the different alcohol ligands coordinated to Ni1 in axial positions. So the environment of the terminal NiII ion could be best described as an octahedral topology with the six-coordinated. Furthermore, the coordination environment of the central Ni2 ion is composed of four µ-phenoxo oxygen (O1, O4, O1# and O4#) atoms from two (L)2− moieties and two µ-acetato oxygen (O8 and O8#) atoms which adopt a usual µ–O-C-O fashion. Four oxygen (O1, O4, O1# and O4#) atoms form the basal plane, and two oxygen (O8 and O8#) atoms situated in the axial positions; all the six oxygen atoms bind to Ni2 forming an octahedral configuration. Consequently, all the six-coordinated NiII ions of complexes 1, 2, 3 and 4 have a slightly distorted octahedral coordination polyhedron.

Supramolecular Interactions of NiII Complexes 1, 2, 3 and 4

The molecular structures of NiII complexes 1, 2, 3 and 4 are similar to each other, but because of the intra- and inter-molecular hydrogen bond interactions (Table 3), their supramolecular structures are different. As depicted in Figure 5, in NiII complex 1, two pairs of intra-molecular C9-H9B···O7 and C2-H2···O8 hydrogen bonds are formed. The proton (-C2H2) of benzene rings of the (L)2− moiety is hydrogen-bonded to the O8 atom of the acetato ligand. The proton (-C9H9B) of ethylenedioxime carbons (C9) of the (L)2− units is hydrogen-bonded to the O7 atom of the acetato ligand, and two pairs of inter-molecular O6-H6···O9 and O9-H9···O8 hydrogen bonds are formed. The proton (-O6H6) of the methanol molecules is hydrogen-bonded to the O9 atom of the methanol molecule. The proton (-O9H9) of the methanol molecule is hydrogen-bonded to the O8 atom of the acetato ligand.
In complex 2, two pairs of intra-molecular C8-H8A···O7 and C20-H20B···O3 hydrogen bonds are formed. The proton (-C8H8A) of ethylenedioxime carbons (C8) of the (L)2− units is hydrogen-bonded to the O7 atom of the acetato ligand. The proton (-C20H20B) of the ethanol molecule is hydrogen-bonded to the O3 atom of ethylenedioxime. As depicted in Figure 6, two pairs of inter-molecular O6-H6···O9 and O9-H9B···O8 hydrogen bonds are formed. The proton (-O6H6) of the ethanol molecule is hydrogen-bonded to the O9 atom of the H2O molecule. The proton (-O9H9) of the H2O molecule is hydrogen-bonded to the O8 atom of the acetato ligand.
As depicted in Figure 7, three pairs of intramolecular C2-H2···O8, C8-H8A···O7 and C13-H13···O8 hydrogen bonds are formed. The proton (-C2H2) of benzene rings of the (L)2− moiety is hydrogen-bonded to the O8 atom of the acetato ligand. The O7 atom of the acetato ligand is hydrogen-bonded to the C8H8A group of ethylenedioxime. The proton (-C13H13) of benzene rings of the (L)2− moiety is hydrogen-bonded to the O8 atom of the acetato ligand, and three pairs of inter-molecular O6-H6A···O9, O6-H6B···O9 and O9-H9D···O8 hydrogen bonds are formed. The proton (-O6H6A and -O6H6B) of propanol is hydrogen-bonded to the O9 atom of the H2O molecule. The proton (-O9H9D) of the H2O molecule is hydrogen-bonded to the O8 atom of the acetato ligand.
As depicted in Figure 8, two pairs of intra-molecular C8-H8B···O7 and C13-H13···O1 hydrogen bonds are formed. The proton (-C8H8B) of ethylenedioxime carbons is hydrogen-bonded to the O7 atom of the acetato ligand. The proton (-C13H13) of benzene rings of the (L)2− moiety is hydrogen-bonded to the phenolic O1 atom.

3.2. IR Spectra

The IR spectra of H2L and its corresponding NiII complexes 1, 2, 3 and 4 exhibited several distinguishable resonances in the region of 400–4000 cm−1 and are depicted in Table 4 and Figure S1.
The free ligand H2L showed a broad typical O-H band at 3165 cm−1. The vanishing of these bands in the FT-IR spectra of NiII complexes 1, 2, 3 and 4 indicated that the O-H groups of H2L have been deprotonated and coordinated to the NiII ions [89]. The free ligand H2L exhibited a typical C=N stretching band at 1632 cm−1, which is moved to 1608, 1608, 1612 and 1609 cm−1 in NiII complexes 1, 2, 3 and 4, respectively, exhibiting a weak π-accepting ability of the deprotonated (L)2− ligand [82]. The strong Ar-O stretching band within the 1263–1213 cm−1 range always appears for the Salen-like ligands. This band occurred at 1260 cm−1 for H2L, and at 1219, 1217, 1219 and 1215 cm−1 for NiII complexes 1, 2, 3 and 4, respectively. The Ar-O stretching band is waved to lower frequency, exhibiting that Ni-O(phenolic) bonds are formed in NiII complexes 1, 2, 3 and 4.
The far-infrared spectra of NiII complexes 1, 2, 3 and 4 are gained in the region of 500–100 cm−1 in order to identify Ni-N and Ni-O bonds. The spectrum showed ν(Ni-N) and ν(Ni-O) frequencies of NiII complex 1 at 588 and 420 cm−1, NiII complex 2 at 592 and 410 cm−1, NiII complex 3 at 592 and 409 cm−1, and NiII complex 4 at 590 and 419 cm−1, indicating that the NiII ions are bonded by N2O2 donor atoms of the (L)2− moieties. Hence, it gives evidence for the coordination of H2L with the NiII ions. These assignments are consistent with the literature frequency values [90].

3.3. UV–Vis Absorption Spectra

The UV–Vis spectra of H2L and its NiII complexes 1, 2, 3 and 4 were determined in 1.0 × 10−5 mol·L−1 ethanol solution (Figure 9). The spectrum of H2L includes two relatively intense bands at 274 and 309 nm, attributed to the π–π* transitions of the benzene rings in the salicylaldehyde and oxime groups [91]. Upon coordination of H2L, the band at ca. 309 nm disappears, indicating that the oxime nitrogen atoms are coordinated to the NiII ions. The intraligand π–π* transition of the benzene rings of salicylaldehyde is slightly waved, and appears at 278, 276, 277 and 279.5 nm in NiII complexes 1, 2, 3 and 4, respectively. The new bands observed at 349, 348, 350 and 349 nm for NiII complexes 1, 2, 3 and 4, respectively, are attributed to typical bands that are a result of mixing of L → M charge-transfer transitions with the d-d transitions of A 2 g 3 → T 1 g 3 ( P ) for octahedral Ni(II) ions, which are characteristic of transition metal N2O2 complexes and that of the spin-allowed d–d transition A 2 g 3 → T 1 g 3 ( F ) and the A 2 g 3 → T 2 g 3 ( F ) transition which usually appear after 600 nm.

3.4. Fluorescence Properties

The emission spectra of H2L and its NiII complexes in dilute ethanol solution (c = 1.0 × 10−5 mol·L−1) at room temperature are depicted in Figure 10. The ligand H2L has no intense photoluminescence upon excitation at 350 nm. NiII complexes 1, 2, 3 and 4 showed photoluminescence with maximum emissions at ca. 407.9, 411.8, 415, 392.9 nm upon excitation at 350 nm, respectively. NiII complexes 1, 2, 3 and 4 showed intense photoluminescence which includes that fluorescence characteristics that have been affected by the introductions of the NiII ions.

3.5. Magnetic Properties

Because of the similar structure of the composites 1–4, there is little difference in their magnetic properties. Only the magnetic property of complex 2 is discussed. Magnetic analysis of complex 2 was measured under the applied magnetic field of 1000 Oe, and magnetic susceptibility data of complex 2 were measured within the 2–300 K temperature range. Samples were measured with the single crystals of complex 2. The temperature dependence of magnetic susceptibilities of NiII complex 2 is depicted in Figure 11, as a plot of χMT against T. The χMT value of 3.88 cm3·K·mol−1 at 300 K for trinuclear NiII complex 2 is slightly higher than the value of 3.00 cm3·K·mol−1 expected for three NiII (3d8, S = 1) isolated ions. When decreasing the temperature, the χMT plot decreases very slowly till about 125 K and then begins to drop down sharply and reaches a minimum value of 0.58 cm3·K·mol−1 at 2 K, suggesting that the dominant antiferromagnetic interactions are propagated between NiII ions. There is no peak in the χM vs. T plot. Therefore, no long-range magnetic ordering is found.
The temperature dependence of the reciprocal susceptibility ( χ M − 1 ) follows the Curie–Weiss law (χM = C/(T − θ)) with a Weiss constant θ = −10.0549 K and Curie constant C = 4.0124 cm3·K·mol−1 indicating a dominated intramolecular antiferromagnetic interaction. Inspection of the molecular structure reveals that one main exchange pathway exists in the interaction between Ni1∙∙∙Ni2 by two μ2-O (O1, O1A and O4, O4A). In order to analyze the experimental data of this linear antimagnetic ion core of Ni3O8 (Inset Figure 11), we tried to simulate the data by using the spin Hamiltonian H ^ = − 2 J [ ( S ^ 1 S ^ 2 ) + ( S ^ 2 S ^ 3 ) ] to treat exchange interaction (J) between NiII ions, so the resulting magnetic susceptibility equation is:
χ M = 2 N g 2 β 2 3 k T { A B }
A = 3 x 10 + 18 x 6 + 3 x 4 + 15 x 2 + 42
B = 3 x 10 + x 8 + 8 x 6 + 3 x 4 + 5 x 2 + 7
x = e − J / kT
J is the intramolecular exchange integral between NiII ions, and the other symbols have their usual meanings. The best fitting for the experimental data of complex 2 gives J = −2.96 cm−1, g = 2.30 and the agreement factor R = ∑ [   ( χ M T ) o b s d −   ( χ M T ) c a l c ] 2 / ∑   ( χ M T ) o b s d 2 is 2.51 × 10−4. The small negative value of J also indicates that a weak antiferromagnetic interaction is operative between the NiII ions. The antiferromagnetic parameters of complex 2 are close to other NiII complex [92].

3.6. Solvent Effect

The structures revealed that the structural features of complexes 1, 2, 3 and 4 are found to be similar except for the distinction of coordinated and/or crystallizing solvent molecules. Most notably, the solvent has an effect on the four complexes and causes their slight distinctions in the structures. The influence of solvent effect is obviously exhibited in bond distances and angles for complexes 1, 2, 3 and 4 (Table 2). Notably, the bond lengths from the O6 atom of coordinated methanol, ethanol, n-propanol or i-propanol molecules to the terminal NiII ions in complexes 1, 2, 3 and 4 are 2.121(3), 2.126(3), 2.118(3) and 2.352(4) Ǻ, respectively, which give a basic regular elongation except n-propanol when the steric hindrance successively becomes larger from methanol, ethanol, n-propanol to i-propanol. Furthermore, in complexes 1, 2, 3 and 4, two imino nitrogen and two phenolic oxygen atoms form the square base with the Ni–N bonds being slightly longer than the corresponding Ni–O bonds. The elongation of the Ni–N bonds is probably owing to the weaker coordination abilities of the nitrogen atoms than of phenolic oxygen atoms. Meanwhile, the angle N1–Ni1–N2 (106.18(16), 99.88(17), 106.24(12) and 98.0(2)°) and O1–Ni1–O4 (79.56(13), 81.13(11),79.16(9) and 85.73(12)°) formed two imino nitrogen with the terminal NiII ions as well as two phenolic oxygen atoms with the terminal NiII ions in NiII complexes 1, 2, 3 and 4 are all different, respectively. That is to say, there is a difference between the degree of distortion of the octahedral geometries of the terminal NiII ions in complexes 1, 2, 3 and 4 because of the solvent effect. In addition, in spite of the supra-molecular structures, complexes 1, 2, 3 and 4 also have a similar 0-dimensional structure, which linked by different intra-molecular and/or inter-molecular hydrogen bond interactions. The solvent effects also lead to the changes in UV–Vis, IR spectra, and fluorescence properties in complexes 1, 2, 3 and 4.

4. Conclusions

Four new synthesized NiII complexes 1, 2, 3 and 4 have been designed and characterized structurally. X-ray crystal structure determinations revealed that the structural features of complexes 1, 2, 3 and 4 are similar except for the differences in the coordinated and/or crystallizing solvent molecules. They are all tri-nuclear structures with three NiII ions, two ligand (L)2− moieties, two acetate ligands and two coordinated solvent molecules. Although different solvent molecules are induced in the four NiII complexes, it is worth noting that all of the NiII ions in complexes 1, 2, 3 and 4 are six-coordinated and possess slightly distorted octahedrons, with different distortion degrees of the octahedral geometries around the NiII ions. Interestingly, the existence of the solvent effect in complexes 1, 2, 3 and 4 may be responsible for the slight differences in their crystal and fluorescence properties. In addition, magnetic susceptibility research performed for complex 2 indicated that the magnetic exchange between the NiII ions exhibited antiferromagnetic interactions.

Supplementary Materials

The following are available online at https://www.mdpi.com/2073-4352/8/4/176/s1, Figure S1: The IR spectra of H2L and its corresponding NiII complexes 1, 2, 3 and 4, Table S1: Crystal data and structure refinements for NiII complexes 2, 3 and 4.

Acknowledgments

This work was supported by Program for Excellent Team of Scientific Research in Lanzhou Jiaotong University (201706), which is gratefully acknowledged.

Author Contributions

Yin-Xia Sun conceived and designed the experiments; Jing Li and Hong-Jia Zhang performed the experiments; Jian Chang and Hao-Ran Jia analyzed the data; Yong-Qing Huang contributed analysis tools; Jing Li wrote the paper.

Conflicts of Interest

The authors declare no conflict of interest.

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Crystals 08 00176 sch001 550
Scheme 1. The synthetic route to H2L.
Scheme 1. The synthetic route to H2L.
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Figure 1. Molecular structure of complex 1.
Figure 1. Molecular structure of complex 1.
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Figure 2. Molecular structure of complex 2.
Figure 2. Molecular structure of complex 2.
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Figure 3. Molecular structure of complex 3.
Figure 3. Molecular structure of complex 3.
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Figure 4. Molecular structure of complex 4.
Figure 4. Molecular structure of complex 4.
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Figure 5. Intra- and inter-molecular hydrogen bonds of NiII complex 1.
Figure 5. Intra- and inter-molecular hydrogen bonds of NiII complex 1.
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Figure 6. Intra- and inter-molecular hydrogen bonds of NiII complex 2.
Figure 6. Intra- and inter-molecular hydrogen bonds of NiII complex 2.
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Figure 7. Intramolecular hydrogen bonds of NiII complex 3.
Figure 7. Intramolecular hydrogen bonds of NiII complex 3.
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Figure 8. Intramolecular hydrogen bonds of the NiII complex 4.
Figure 8. Intramolecular hydrogen bonds of the NiII complex 4.
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Figure 9. UV–Vis spectra of H2L and its NiII complexes 1, 2, 3 and 4 in ethanol solution (c = 1.0 × 10−5 mol·L−1).
Figure 9. UV–Vis spectra of H2L and its NiII complexes 1, 2, 3 and 4 in ethanol solution (c = 1.0 × 10−5 mol·L−1).
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Figure 10. Emission spectra of NiII complexes 1, 2, 3 and 4 (λex = 350 nm) in ethanol solution (c = 1 × 10−5 mol·L−1).
Figure 10. Emission spectra of NiII complexes 1, 2, 3 and 4 (λex = 350 nm) in ethanol solution (c = 1 × 10−5 mol·L−1).
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Figure 11. Temperature dependence of χMT and χM versus T of 2. Inset: temperature dependence of χM−1; the solid line represents the best fit of the Curie−Weiss law χM = C/(T − θ).
Figure 11. Temperature dependence of χMT and χM versus T of 2. Inset: temperature dependence of χM−1; the solid line represents the best fit of the Curie−Weiss law χM = C/(T − θ).
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Table
Table 1. Crystal data and structure refinements for NiII complex 1.
Table 1. Crystal data and structure refinements for NiII complex 1.
Molecular FormulaC42H54Ni3N4O18Molecular Weight1079.02
Temperature (K)294.29 (10)Crystal Size, mm30.36 × 0.24 × 0.21
Crystal SystemtetragonalSpace GroupI 41/a
A (Å)30.0337 (6)α (°)90
B (Å)30.0337 (6)β (°)90
C (Å)11.4332 (4)γ (°)90
V (Å3)10312.9 (5)Z8
Dcalc(Mg/m3)1.390μ (mm−1)1.155
F(000)4496hkl Range−40 ≤ h ≤ 37, −22 ≤ k ≤ 40, −15 ≤ l ≤ 8
Θ Range(°)3.3–26.0Reflections Collected/Unique14,913/5038
Rint0.0538Data/Restraints/Parameters5038/17/312
R1/wR2 [I ≥ 2σ(I)]0.0606/0.1649R1/wR2 (All Data)0.0970/0.1842
Goodness Off It (GOF)1.086∆ρmax,min (e Å–3)0.97/−0.37
Table
Table 2. Selected bond lengths (Å) and angles (°) for NiII complexes 1, 2, 3 and 4.
Table 2. Selected bond lengths (Å) and angles (°) for NiII complexes 1, 2, 3 and 4.
Complex 1Complex 2Complex 3Complex 4
BondDistanceBondDistanceBondDistanceBondDistance
Ni1-O12.013(3)Ni1-O12.009(3)Ni1-O12.025(2)Ni1-O11.994(3)
Ni1-O42.037(3)Ni1-O42.007(3)Ni1-O42.011(2)Ni1-O41.999(3)
Ni1-O62.121(3)Ni1-O62.126(3)Ni1-O62.118(3)Ni1-O62.352(4)
Ni1-O72.033(3)Ni1-O72.045(3)Ni1-O72.019(3)Ni1-O72.045(4)
Ni1-N12.079(4)Ni1-N12.029(4)Ni1-N12.077(3)Ni1-N22.030(5)
Ni1-N22.073(4)Ni1-N22.050(4)Ni1-N22.078(3)Ni1-N12.053(5)
Ni2-O12.064(3)Ni2-O12.100(3)Ni2-O12.077(2)Ni2-O12.094(3)
Ni2-O1 #12.064(3)Ni2-O1 #22.100(3)Ni2-O1 #32.077(2)Ni2-O1 #42.094(3)
Ni2-O42.086(3)Ni2-O4 #22.085(3)Ni2-O42.063(2)Ni2-O42.074(3)
Ni2-O4 #12.086(3)Ni2-O42.085(3)Ni2-O4 #32.063(2)Ni2-O4 #42.074(3)
Ni2-O82.091(3)Ni2-O82.065(3)Ni2-O82.096(2)Ni2-O82.019(3)
Ni2-O8 #12.091(3)Ni2-O8 #22.065(3)Ni2-O8 #32.096(2)Ni2-O8 #42.019(3)
BondAngleBondAngleBondAngleBondAngle
O1-Ni1-O479.56(13)O1-Ni1-O689.93(12)O1-Ni1-O690.41(10)O1-Ni1-O485.73(12)
O1-Ni1-O687.46(13)O1-Ni1-O790.97(13)O1-Ni1-N186.81(10)O1-Ni1-O678.59(15)
O1-Ni1-O793.97(13)O1-Ni1-N189.32(15)O1-Ni1-N2166.77(11)O1-Ni1-O791.07(14)
O1-Ni1-N187.47(15)O1-Ni1-N2169.44(14)O4-Ni1-O179.16(9)O1-Ni1-N2164.74(18)
O1-Ni1-N2165.26(16)O4-Ni1-O181.13(11)O4-Ni1-O690.64(10)O1-Ni1-N186.77(18)
O4-Ni1-O693.29(14)O4-Ni1-O692.19(13)O4-Ni1-O792.94(11)O4-Ni1-O678.99(14)
O4-Ni1-N1166.96(14)O4-Ni1-O790.17(13)O4-Ni1-N1165.92(11)O4-Ni1-O789.79(14)
O4-Ni1-N286.86(14)O4-Ni1-N1170.44(14)O4-Ni1-N287.75(11)O4-Ni1-N288.69(17)
O7-Ni1-O491.11(13)O4-Ni1-N289.62(14)O7-Ni1-O192.69(10)O4-Ni1-N1172.17(18)
O7-Ni1-O6175.56(15)O7-Ni1-O6177.58(13)O7-Ni1-O6175.65(10)O7-Ni1-O6165.19(14)
O7-Ni1-N188.42(15)O7-Ni1-N294.15(15)O7-Ni1-N188.80(12)O7-Ni1-N192.63(18)
O7-Ni1-N291.96(14)N1-Ni1-O687.63(17)O7-Ni1-N289.87(14)N2-Ni1-O686.41(18)
N1-Ni1-O687.44(16)N1-Ni1-O790.13(17)N1-Ni1-O688.32(12)N2-Ni1-O7103.11(18)
N2-Ni1- O687.65(14)N1-Ni1-N299.88(17)N2-Ni1-N2106.24(12)N2-Ni1-N198.0(2)
N2-Ni1-N1106.18(16)N2-Ni1-O685.32(15)N2-Ni2-O687.79(14)N1-Ni1-O697.30(19)
O1 #1-Ni2-O1180.00(14)O1-Ni2-O1 #2180.0O1 #3-Ni2-O1180.0O1-Ni2-O1 #4180.0
O1-Ni2-O477.30(12) (12)12O4 #2-Ni2-O1 #277.21(11)O1 #3-Ni2-O891.16(9)O4-Ni2-O1 #498.65(12)
O1 #1-Ni2-O4 #177.30(12)O4-Ni2-O177.21(11)O1 #3-Ni2-O8 #388.84(9)O4-Ni2-O181.35(12)
O1-Ni2-O4 #1102.70(12)O4-Ni2-O1 #2102.79(11)O1-Ni2-O888.84(9)O4 #4-Ni2-O198.65(12)
O1 #1-Ni2-O4102.70(12) (12)12O4 #2-Ni2-O1102.79(11)O1-Ni2-O8 #391.16(9)O4 #4-Ni2-O1 #481.35(12)
O1-Ni2-O8 #190.85 (13)O4-Ni2-O4 #2180.00(9)O4 #3-Ni2-O1103.20(9)O4 #4-Ni2-O4180.0
O1 #1-Ni2-O890.85(13)O8-Ni2-O1 #290.95(12)O4 #3-Ni2-O1 #376.80(9)O8-Ni2-O1 #490.07(13)
O1-Ni2-O889.15(13)O8 #2-Ni2-O190.95(12)O4-Ni2-O1 #3103.20(9)O8 #4-Ni2-O1 #489.93(13)
O1 #1-Ni2-O8 #189.15(13)O8-Ni2-O189.05(12)O4-Ni2-O176.80(9)O8 #4-Ni2-O190.07(13)
O4 #1-Ni2-O4180.0O8 #2-Ni2-O1 #289.05(12)O4-Ni2-O4 #3180.0(9)O8-Ni2-O189.93(13)
O4-Ni2-O889.39(12)O8-Ni2-O4 #290.64(11)O4-Ni2-O8 #390.64(9)O8 #4-Ni2-O490.26(13)
O4 #1-Ni2-O890.61(12)O8 #2-Ni2-O4 #289.36(11)O4 #3-Ni2-O8 #389.36(9)O8 #4-Ni2-O4189.75(13)
O4 #1-Ni2-O8 #189.39(12)O8-Ni2-O489.36(11)O4-Ni2-O889.36(9)O8-Ni2-O4 #490.25(13)
O4-Ni2-O8 #190.61(12)O8 #2-Ni2-O490.64(11)O4 #3-Ni2-O890.64(9)O8-Ni2-O489.75(13)
O8 #1-Ni2-O8180.0O8-Ni2-O8 #2180.00(15)O8-Ni2-O8 #3180.0O8-Ni2-O8 #4180.0
Symmetry transformations used to generate equivalent atoms: #1 1 − x, 1 − y, −z, #2: 1 − x, −y, 1 − z, #3: −x, 1 − y, 1 − z and #4: 2 − x, 2 − y, 1 − z for NiII complexes 1, 2, 3 and 4, respectively.
Table
Table 3. Intra- and inter-molecular hydrogen bonds (Å, °) for complexes 1, 2, 3 and 4.
Table 3. Intra- and inter-molecular hydrogen bonds (Å, °) for complexes 1, 2, 3 and 4.
ComplexD-H···Ad(D-H)d(H···A)d(D···A)∠DHA
1C9-H9B···O70.972.393.242(6)147
C2-H2···O80.932.563.243(7)130
O6-H6···O90.86(3)1.76(3)2.614(7)176(3)
O9-H9···O80.821.932.731(7)165
2C8-H8A···O70.972.183.088(8)156
O20-20B···O3
O6-H6···O9
O9-H9B···O8		0.97
0.87(4)
0.85		2.49
1.77(4)
1.86		3.277(12)
2.626(8)
2.700(7)		139
169(5)
171
3C2-H2···O80.932.583.205(5)125
C8-H8A···O70.972.433.240(7)140
C13-H13···O8
O6-H6A···O9
O6-H6B···O9
O9-H9D···O8		0.93
0.86(5)
0.86(4)
0.86(4)		2.55
1.81(5)
1.82(4)
1.96(8)		3.219(5)
2.643(4)
2.643(4)
2.712(5)		129
161(4)
161(7)
146(8)
4C8-H8B···O70.972.223.134(9)156
C13-H13···O10.932.413.195(6)142
Table
Table 4. Selected FT-IR data for H2L and its NiII complexes 1, 2, 3 and 4 (cm−1).
Table 4. Selected FT-IR data for H2L and its NiII complexes 1, 2, 3 and 4 (cm−1).
Compoundν(PhO-H)ν(C=N)ν(Ar-O)ν(Ni-N)ν(Ni-O)
H2L316516321260
Complex 1 16081219588420
Complex 2 16081217592410
Complex 3 16121219592409
Complex 4 16091215590419

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Li, J.; Zhang, H.-J.; Chang, J.; Jia, H.-R.; Sun, Y.-X.; Huang, Y.-Q. Solvent-Induced Unsymmetric Salamo-Like Trinuclear NiII Complexes: Syntheses, Crystal Structures, Fluorescent and Magnetic Properties. Crystals 2018, 8, 176. https://doi.org/10.3390/cryst8040176

AMA Style

Li J, Zhang H-J, Chang J, Jia H-R, Sun Y-X, Huang Y-Q. Solvent-Induced Unsymmetric Salamo-Like Trinuclear NiII Complexes: Syntheses, Crystal Structures, Fluorescent and Magnetic Properties. Crystals. 2018; 8(4):176. https://doi.org/10.3390/cryst8040176

Chicago/Turabian Style

Li, Jing, Hong-Jia Zhang, Jian Chang, Hao-Ran Jia, Yin-Xia Sun, and Yong-Qing Huang. 2018. "Solvent-Induced Unsymmetric Salamo-Like Trinuclear NiII Complexes: Syntheses, Crystal Structures, Fluorescent and Magnetic Properties" Crystals 8, no. 4: 176. https://doi.org/10.3390/cryst8040176

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