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Article

Tetra-, Penta- and Hexa-Coordinated Transition Metal Complexes Constructed from Coumarin-Containing N2O2 Ligand

School of Chemical and Biological Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
*
Author to whom correspondence should be addressed.
Crystals 2018, 8(2), 77; https://doi.org/10.3390/cryst8020077
Submission received: 10 January 2018 / Revised: 29 January 2018 / Accepted: 30 January 2018 / Published: 1 February 2018
(This article belongs to the Section Crystal Engineering)

Abstract

:
Three newly designed complexes, [Cu(L)]·CHCl3 (1), [Co(L)(MeOH)]·CHCl3 (2) and [{Ni(L)(MeOH)(PhCOO)}2Ni] (3) a coumarin-containing Salamo-type chelating ligand (H2L) have been synthesized and characterized by elemental analyses, IR and UV-VIS spectra, and X-ray crystallography. Complex 1 includes one Cu(II) atom, one completely deprotonated (L)2− unit and one crystalling chloroform molecule, the Cu(II) atom shows a square-planar geometry. Complex 2 includes one Co(II) atom, one completely deprotonated (L)2− unit, one coordinated methanol molecule and one crystalling chloroform molecule. The Co(II) atom is a distorted trigonal-bipyramidal geometry. While complex 3 includes three Ni(II) atoms, two completely deprotonated (L)2− units, two benzoates and two coordinated methanol molecules. The complexes 1 and 2 are both possess three-dimensional supra-molecular structures by abundant noncovalent interactions. But, complex 3 formed a two-dimensional supra-molecular structure by intra-molecular hydrogen bonds. In addition, the antimicrobial and fluorescence properties of H2L and its complexes 1, 2 and 3 were also investigated.

Graphical Abstract

1. Introduction

Salen compound is a kind of versatile tetradentate N2O2 chelating ligand in modern coordination chemistry [1,2,3,4,5,6,7], and its metal complexes have been diffusely investigated in biological fields [8,9,10], ion recognitions [11], luminescent [12,13,14,15,16,17] and magnetic [18,19,20,21] materials, supra-molecular buildings [22,23,24,25,26] and so on. Especially, some substitution of atoms of the ligand with other elements often evidently improves its properties. When an O-alkyl oxime unit substitutes the imine moiety, the larger electronegativity of the O atoms is predicted to improve significantly the electronic behaviors of Salamo-type compounds, which may give rise to novel structures and better properties of the metal(II) complexes [27,28,29,30,31,32,33].
The introduction of different substituted groups into Salamo-type compounds may give rise to novel structures and the uncoordinated crystalling molecule can also affect the spatial structures [34,35,36]. Although these Salamo-type complexes have been in the process of development, the fluorescence and antimicrobial properties with coumarin-containing transition metal complexes are still unreported. In this study, three newly designed complexes [Cu(L)]·CHCl3 (1), [Co(L)(MeOH)]·CHCl3 (2) and [{NiL(MeOH)(PhCOO)}2Ni] (3) have been prepared with a coumarin-containing Salamo-type N2O2 ligand, in particular the research on the Salamo-type complex contained benzoate ligands is reported firstly.

2. Experimental

2.1. Materials and Methods

7-Hydroxyl-4-methyl-coumarin (98%) was obtained from Alfa Aesar (New York, NY, USA). C, H and N analyses were gained by a GmbH VarioEL V3.00 automatic elemental analysis instrument (Elementar, Berlin, Germany). Elemental analyses for metals were obtained using an IRIS ER/S-WP-ICP atomic emission spectrometer (Elementar, Berlin, Germany). Melting points were measured by the use of a microscopic melting point apparatus made by Beijing Taike Instrument Limited Company (Beijing, China) and were uncorrected. IR spectra were recorded on a Vertex70 FT-IR spectrophotometer, with samples prepared as KBr (400–4000 cm−1) pellets (Bruker AVANCE, Billerica, MA, USA). UV-VIS absorption spectra were measured on a Shimadzu UV-3900 spectrometer (Shimadzu, Tokyo, Japan). Luminescence spectra in solution were recorded on a Hitachi F-7000 spectrometer (Shimadzu, Tokyo, Japan). 1H-NMR spectra were measured by a German Bruker AVANCE DRX-400 spectrometer (Bruker AVANCE, Billerica, MA, USA). X-ray single-crystal structures were determined by a SuperNova Dual (Cu at zero) and Bruker APEX-II CCD diffractometers (Bruker AVANCE, Billerica, MA, USA), respectively.

2.2. Synthesis of H2L

Major reaction step, O,O′-ethane-1,2-diyl-bis-hydroxylamine was prepared following the literature [37,38,39]. 7-Hydroxy-4-methyl-2-oxo-2H-chromene-8-carbonitrile was synthesized in accordance with the reported procedures [40]. The major reaction steps participated in the preparation of H2L are shown in Scheme 1.
An ethanol solution (15 mL) of 7-Hydroxy-4-methyl-2-oxo-2H-chromene-8-carbonitrile (384.38 mg, 1.45 mmol) was added dropwise to an ethanol solution (15 mL) of O,O′-ethane-1, 2-diyl-bis-hydroxylamine (46.00 mg, 0.5 mmol) in ethanol (15 mL) and the mixture was subjected to heating at 65~70 °C for 3 h. After cooling to the room temperature, the resulting white solid was collected. Yield, 186.47 mg, 0.40 mmol (80.3%). Anal. Calcd for C24H20N2O8 (%): C, 62.07; H, 4.34; N, 6.03; Found: C, 62.25; H, 4.47; N, 5.89. 1H-NMR (400 MHz, CDCl3), δ 10.72 (s, 2H, OH), 8.95 (s, 2H, CH=N), 7.50 (d, J = 8.9 Hz, 2H, ArH), 6.93 (d, J = 8.9 Hz, 2H, ArH), 6.14 (s, 2H, ArH), 4.54 (s, 4H, CH2), 2.40 (s, 6H, CH3).

2.3. Synthesis of Complex 1

A chloroform solution (4 mL) of H2L (4.64 mg, 0.01 mmol) was added dropwise to a methanol solution (4 mL) of Cu(OAc)2·H2O (1.99 mg, 0.01 mmol), the color of the mixed solution changes immediately to dark green. The mixed solution was filtered, and the filtrate was kept undisturbed in the dark to avoid decomposition of the coumarin-containing building blocks. Single-crystals suitable for X-ray crystallography were grown up by partial solvent evaporation after about two weeks, and collected carefully by filtration, washed with n-hexane, and dried at room temperature. Yield, 3.01 mg, 0.0047 mmol (46.7%). Anal. Calc. for C25H19Cl3CuN2O8 (%): C, 46.53; H, 2.97; N, 4.34; Cu, 9.85; Found: C, 46.69; H, 3.02; N, 4.17; Cu, 9.71.

2.4. Synthesis of Complex 2

A solution of H2L (4.64 mg, 0.01 mmol) in 4 mL of chloroform was added dropwise to a methanol solution (6 mL) of Co(NO3)2·6H2O (2.91 mg, 0.01 mmol). The color of the mixed solution changes immediately to brown. The mixed solution was filtered, and the filtrate kept undisturbed in the dark to avoid decomposition of the coumarin-containing building blocks. Single-crystals suitable for X-ray crystallography were grown up by partial solvent evaporation after about one week, and collected carefully by filtration, washed with n-hexane, and dried at room temperature. Yield, 3.32 mg, 0.0049 mmol (49.3 %). Anal. Calc. for C26H23Cl3CoN2O9 (%): C, 46.42; H, 3.45; N, 4.16; Co, 8.76; Found: C, 46.61; H, 3.57; N, 4.02; Co, 8.61.

2.5. Synthesis of Complex 3

A chloroform solution (4 mL) of H2L (4.64 mg, 0.01 mmol) was added dropwise to a methanol solution (2 mL) of Ni(NO3)2·6H2O (2.90 mg, 0.01 mmol). Then, a methanol solution (5 mL) of sodium benzoic (1.22 mg, 0.01 mmol) was added, and the mixed sulution was kept stirring for 5 min at room temperature. The mixed solution was filtered, and the filtrate kept undisturbed in the dark to avoid decomposition of the coumarin-containing building blocks. Single-crystals suitable for X-ray crystallography were grown up by partial solvent evaporation after about three weeks, and collected carefully by filtration, washed with n-hexane, and dried at room temperature. Yield, 2.05 mg, 0.0015 mmol (43.7%). Anal. Calc. for C64H54N4Ni3O22 (%): C, 54.62; H, 3.87; N, 3.98; Ni, 12.51; Found: C, 54.81; H, 3.93; N, 3.83; Ni, 12.33.

2.6. X-ray Crystal Structure Determinations for Complexes 1, 2 and 3

X-ray single crystal diffraction data of the complexes 1, 2 and 3 were recorded using a SuperNova Dual (Cu at zero) and Bruker APEX-II CCD diffractometers with a monochromated Mo- radiation (λ = 0.71073 Å) source at 296(2), 173.00(10) and 153(2) K, respectively. The LP corrections were applied to the SAINT program [41] and Semi-empirical correction were applied to the SADABS program [42]. The single crystal structures were solved by the direct methods (SHELXS-2014) [43]. All hydrogen atoms were added theoretically and difference-Fourier map exhibited the positions of the remaining atoms. The H atoms were included at the calculated positions and constrained to ride on their parent atoms. All non-hydrogen atoms were refined anisotropically by a full-matrix least-squares procedure on F2 with SHELXL-2014 [43]. Crystal data and refinement parameters involved the structure determinations are presented in Table 1.
Crystallographic data have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication, No. CCDC 1,816,001, 1,816,000 and 1,816,002 for complexes 1, 2 and 3, respectively. Copies of the data can be gained free of charge on application to CCDC, 12 Union Road, Cambridge CB21EZ, UK (Telephone: (44) 01223 762910; Fax: +44-1223-336033; E-mail: [email protected]). These data can be also obtained free of charge at www.ccdc.cam. Ac.uk/conts/retrieving.html.

3. Results and Discussion

Complexes 1, 2 and 3 a coumarin-containing Salamo-type ligand have been prepared, and characterized by IR, UV-VIS and X-ray crystallography methods. In addition, the fluorescence properties of complexes 1, 2 and 3 and antimicrobial activities of H2L and its complexes 1, 2 and 3 were also investigated.

3.1. IR Spectra

The FT-IR spectra of H2L with its corresponding complexes 1, 2 and 3 possess different bands in the 4000–400 cm−1 region (Figure 1 and Table 2).
The characteristic C=O stretching band at 1734 cm−1 of the ligand H2L, and those of the complexes 1, 2 and 3 emerge at 1722, 1726 and 1719 cm−1, respectively [44]. Meanwhile, a characteristic C=N stretching band of H2L emerges at 1616 cm−1, and those of complexes 1, 2 and 3 show at 1601, 1597 and 1605 cm−1, respectively [45]. The characteristic C=N stretching frequencies are moved to low frequencies, which indicates that the metal(II) atoms are bonded by azomethine N atoms of the ligand (L)2− moieties [46]. H2L presents a characteristic Ar–O stretching frequency at 1282 cm-1, while those of complexes 1, 2 and 3 emerge at 1242, 1238 and 1222 cm−1, respectively. The characteristic Ar–O stretching frequencies are moved to low frequencies, which can be evidence for formation of Cu–O, Co–O and Ni–O bonds between Cu(II), Co(II) and Ni(II) atoms with O atoms of phenolic groups [47].

3.2. UV-VIS Spectra

The UV–VIS absorption spectra of H2L with its complexes 1, 2 and 3 in the dichloromethane solutions (2.0 × 10−5 M) at 298 K are shown in Figure 2 and Table 3. The absorption peaks of H2L are different from its complexes 1, 2 and 3. The absorption spectrum of H2L comprises three relatively intense absorption peaks centered at 291, 330 and 345 nm, the first peak at 291 nm can be assigned to the π–π* transitions of the phenyl rings [48], the second peak at 330 nm can be assigned to the π–π* transitions of the oxime group [49], and the third peak at 345 nm can be assigned to the n–π* transitions of lactone carbonyl group [50]. Upon coordination of H2L, the π–π* transitions of the phenyl rings in complexes 1 and 2 are bathochromically shifted to 299 and 297 nm, respectively, and the absorption peak at 291 nm vanishes from the UV–VIS spectrum of complex 3, indicating the coordination of Co(II), Cu(II) and Ni(II) atoms with the (L)2− units [48]. Compared with H2L, the absorption peak at 330 nm vanishes from the UV–VIS spectra of complexes 1, 2 and 3, indicating that the oxime N atoms are participated in coordination to the Cu(II), Co(II) and Ni(II) atoms [49]. Meanwhile, the n–π* transitions of the lactone carbonyl group in complexes 1, 2 and 3 assumes a hypsochromic shift to 343, 347 and 338 nm exhibiting that the coordination of the (L)2− units with Cu(II), Co(II) and Ni(II) atoms, respectively. Meanwhile, three weak broad absorption peaks are gained at 396, 399 and 391 nm for complexes 1, 2 and 3, respectively, these new absorption peaks can be attributed to L→M charge-transfer transitions (LMCT). This is characteristic of N2O2-donors sphere with the transition metal complexes [49].

3.3. Fluorescence Properties

The fluorescent properties of H2L and its complexes 1, 2 and 3 were measured at room temperature (Figure 3). The ligand H2L exhibits a strong and broad emission at 432 nm upon excitation at 351 nm, which should be assigned to intraligand π–π* transition [12]. The complexes 1, 2 and 3 display weakened photoluminescence with maximum emission peaks at ca. 417, 462 and 469 nm upon excitation at 351 nm, respectively. The absorption peaks are bathochromically-shifted of complexes 1 and 2, and hypsochromically-shifted of complex 3, which could be attributed to LMCT [12].

3.4. Crystal Structure Description of Complex 1

As presented in Figure 4 and Table 4, complex 1 crystallizes in the monoclinic system, space group P 21/c, which comprises one Cu(II) atom, one deprotonated (L)2− unit and one crystalling chloroform molecule.
The Cu(II) atom is tetra-coordinated by two oxime N (N1 and N2) atoms and two deprotonated phenoxo O (O1 and O2) atoms, the four atoms are all from one deprotonated (L)2− unit (Figure 4a). Geometry of Cu(II) atom can be best described as a slightly distorted square-planar with CuN2O2 coordination and deduced by using τ4 index, τ4 = 0.258 (Figure 4b) [51]. The two phenolic O (O1 and O2) atoms and the two oxime N (N1 and N2) atoms of the (L)2− unit compose together the basal (Cu1-O1, 1.891(3); Cu1-O2, 1.909(3); Cu1-N1, 1.950(4) and Cu1-N2, 1.976(4) Å) with N2 and O2 above average by 0.239(2) and 0.292(2) Å, and N1 and O1 below average by 0.241(2) and 0.289(2) Å, respectively. Additionally, dihedral angles between the basal planes (N2O2 plane) and the benzene rings are 13.17(2)° and 14.74(2)°, respectively, which defined as shown in Figure 5a. Dihedral angle of planes N1-Cu1-N2 and O1-Cu1-O2 is 22.37(2)° (Figure 5b) [52].
As illustrated in Figure 6 and Table 5, complex 1 molecules form an infinite three-dimensional supra-molecular structure by inter-molecular hydrogen bonds, four pairs of inter-molecular hydrogen bonds C12-H12B···O1, C20-H20···O3, C25-H25···O8 and C12-H12A···Cl1 are formed [53].

3.5. Crystal Structure Description of Complex 2

Complex 2 presents a symmetric mononuclear structure, crystallizes in the monoclinic system, space group P 21/c, composes one Co(II) atom, one deprotonated (L)2− unit, one coordinated methanol molecule and one crystalling chloroform molecule. Selected bond lengths and angles are listed in Table 6.
As shown in Figure 7, the Co(II) atom is penta-coordinated by two oxime N (N1 and N2) and phenoxo O (O1 and O6) atoms from one deprotonated (L)2− unit, and one O (O9) atom from the coordinated methanol molecule (Figure 7a). The coordination around the Co(II) atom is depicted as a trigonal bipyramid [54], and the τ value was estimated to be τ = 0.888 (Figure 7b) [55]. The phenolic O (O6) atom and the oxime N (N1) atom of the (L)2− unit and one O (O9) atom of the coordinated methanol molecule compose together the basal plane (Co1-O6, 1.926(3); Co1-N1, 2.014(3) and Co1-O9, 2.039(3) Å), and other phenolic O (O6) atom and oxime N (N1) atom of the (L)2− unit hold the axial positions (Co1-O1, 2.008(3) and Co1-N2, 2.150(3) Å). The dihedral angles of the N2O2 basal plane and the benzene rings are 30.35(2)° and 33.16(2)°, respectively, which defined as shown in Figure 8a. The dihedral angle of the planes N1-Co1-N2 and O1-Co1-O2 is 55.11(2)° (Figure 8b) [56].
As shown in Figure 9 and Table 7, the three-dimensional supra-molecular network of complex 2 is made up of two parts. The first part is linked by inter-molecular hydrogen bond interactions, and five pairs of inter-molecular hydrogen bonds, C9-H9···O2, C6-H6···O6, C13-H13B···O2, C26-H26···O8 and C25-H25C···Cl3 are formed. The another part is made up of the C-Cl···π interactions. The Cg6 (C15–C16–C17–C18–C20–C23) of phenyl as acceptors forms two stacking interactions with the protons (-C26Cl1 and -C26Cl2). The Cg4 (O7–C19–C23) of pyrone ring as acceptor forms one stacking interaction with -C26Cl2. In addition, complex 2 molecules form a three-dimensional infinite structure by O-H···O, C-H···O, C-H···Cl hydrogen bonds and C-Cl···π stacking interactions [57,58].

3.6. Crystal Structure Description of Complex 3

As illustrated in Figure 10 and Table 8, complex 3 exhibits a symmetric trinuclear structure, crystallizes in the triclinic system, space group P–1, includes two completely deprotonated (L)2− units, three Ni(II) atoms, two benzoates and two coordinated methanol molecules.
The terminal Ni2 atom is hexa-coordinated by two phenolic O (O3 and O9) and two oxime N (N1 and N2) atoms of the completely deprotonated (L)2− moity, one O (O7) atom from the coordinated benzoate group and one O (O6) atom from the coordinated methanol molecule. The terminal Ni2 atom possesses a distorted octahedron geometry [59]. The two oxime N (N1 and N2) and phenolic O (O3 and O9) atoms are in mutually cis-positions. Then, the central Ni1 atom is completed by double μ2-phenoxo O (O3 and O9) atoms from two (L)2− moities and two O (O8 and O8#) atoms from two benzoate groups. Each of the benzoate groups bridges the central Ni1 and terminal Ni2 atoms in the syn-syn bridging mode, as a result the central Ni1 atom finally possesses an O2O2O2 coordination environment (Figure 10b) [59]. The dihedral angles between the benzene rings of (L)2− moities and the N2O2 basal plane are 32.87(2)° and 23.66(2)°, respectively, which defined as shown in Figure 11a. The dihedral angle between the planes of N1–Ni2–N2 and O3–Ni2–O9 is 6.50(2)° (Figure 11b) [59].
As depicted in Figure 12 and Table 9, in complex 3, seven pairs of intra-molecular hydrogen bonds C8-H8···O8, C8-H8···O9, C11-H11···O2, C12-H12B···N2, C13-H13B···O7, C14-H14···O10 and C32-H32C···O8 are formed [60,61]. The protons (-C11H11) and (-C14H14) of (L)2− moities form hydrogen bondings with two ester O (O2 and O10) atoms of (L)2− moities, respectively. The proton (-C12H12B) from ethylenedioxime carbon atom of (L)2− moities forms hydrogen bonding with oxime N (N2) atom. The proton (-C13H13B) from ethylenedioxime carbon atom of the (L)2− moitie forms hydrogen bonding with carboxylate O (O7) atom of coordinated benzoate group. The proton (-C32H32C) from coordinated methanol molecule form hydrogen bonding with O (O8) atom of coordinated benzoate group. The proton (-C8H8) of the (L)2− moity forms hydrogen bonds with phenoxo O (O9) atom of (L)2− moity and carboxylate O (O8) atom of coordinated benzoate group, respectively [62,63].
As illustrated in Figure 13, two pairs of inter-molecular hydrogen bondings, O6-H6···O1 and C12-H12A···O11 are formed. The proton (-C12H12A) of the ((L)2− moity forms hydrogen bondings with the O (O11) atom of four adjacent complex 3 molecules. Meanwhile, the proton (-O6H6) of the coordinated methanol molecule forms hydrogen bondings with the O (O1) atom from the (L)2− moity of four adjacent complex 3 molecules. The space skeleton of complex 3 possesses a two-dimensional supra-molecular structure by the hydrogen bonding interactions [64].
Complexes 1, 2 and 3 with a coumarin-containing Salamo-type ligand H2L have been synthesized, and have different structures depending on the anions and cations used. In complexes 1, 2 and 3, the metal atom located at the Salamo N2O2 unit is tetra-, penta- and hexa-coordinated, respectively. As widely known, the coordination number of Cu(II) atom is generally four or five in Salamo-type Cu(II) complexes and the coordination geometry around Cu(II) atom is planar quadrilateral, tetrahedron or tetragonal pyramid [26,37,49,51]. In complex 1, the coordination number of Cu(II) atom is four, the anions and the solvent molecules were not involved in the coordination. The coordination number of Co(II) atom is generally six, and the coordination geometry around Co(II) atom is octahedron [47,56,63,65]. While in complex 2, the methanol molecule was involved in the coordination forming a mono-nuclear Co(II) complex. The coordination geometry around Co(II) atom is trigonal bipyramid, which is rare in the previously reported Salamo-type Co(II) complexes. In complex 3, both of the anions and the solvent molecules were involved in the coordination, this coordination pattern is frequently appeared in the Salamo-type trinuclear Ni(II) complexes, in which the three Ni(II) atoms are all hexa-coordinated with slightly distorted octahedral geometries [12,31,44,59], but the research on the Salamo-type trinuclear Ni(II) complex contained benzoate ligands is reported firstly.

3.7. Antimicobial Activities

Bacteriostasis tests on common bacteria, such as E. coli and S. aureus, were carried out by the punch method. A small amount (0.1 mL) of a fresh overnight bacterial suspension was added into autoclaved LB (lysogeny broth) agar, then the agar was poured into sterile dishes. The concentration of the test compounds were 0.6, 1.2 and 2.4 mg/mL. 70 µL of samples were added into a burrowed hole measuring 5 mm in diameter with transfer liquid gun when the medium underwent solidification [65,66].
As shown in Figure 14 and Figure 15, the zones of DMF, metal salts, H2L and complexes 1, 2 and 3 have apparent differences in antibacterial activity among two kinds of bacteria. The complexes 1, 2 and 3 displayed more enhanced antimicrobial activities than H2L under the same conditions (2.5 mg/mL), and the DMF and the metal salts also have a weak biological activity. Moreover, E. coli shows stronger antibacterial activity, whereas S. aureus possesses weaker antibacterial activity. This increase in the antibacterial activities of complexes 1, 2 and 3 were accompanied with an increase in concentration and can be explained on the basis of the chelation theory [65,66]. Chelation reduces the polarity of the metal atom mainly due to partial share of positive charge of metal atom with donor groups and possible delocalization of π-electron within the whole chelate ring. Further, it enhances the lipophilic character of the central atom [66].

4. Conclusions

In summary, three newly designed complexes [Cu(L)]·CHCl3 (1), [Co(L)(MeOH)]·CHCl3 (2) and [{Ni(L)(MeOH)(PhCOO)}2Ni] (3) derived from a Salamo-type coumarin-containing ligand (H2L) have been successfully prepared and well characterized. For the central metals, the Cu(II) atom of complex 1 is tetra-coordinated and the Co(II) atom of complex 2 is penta-coordinated with trigonal-bipyramidal geometry, and the Ni(II) atoms of complex 3 are hexa-coordinated possessing slightly distorted octahedral geometries. The complexes 1 and 2 are both possess the three-dimensional supra-molecular structures by abundant noncovalent interactions. But complex 3 is formed a two-dimensional supra-molecular structure by intra-molecular hydrogen bonds. Furthermore, the antimicrobial and fluorescence properties of H2L and complexes 1, 2 and 3 were also studied.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (21761018) and the Program for Excellent Team of Scientific Research in Lanzhou Jiaotong University (201706), which is gratefully acknowledged.

Author Contributions

W.-K.D. supervised the project and contributed materials/reagents/analysis tools; C.L. and F.W. performed the experiments; W.-K.D., L.G. wrote the manuscript.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Zhao, L.; Dang, X.T.; Chen, Q.; Zhao, J.X.; Wang, L. Synthesis, crystal structure and spectral properties of a 2D supramolecular copper(II) complex with 1-(4-{[(E)-3-ethoxyl-2-hydroxybenzylidene]amino}phenyl)ethanone oxime. Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 2013, 43, 1241–1246. [Google Scholar] [CrossRef]
  2. Wu, H.L.; Pan, G.L.; Bai, Y.C.; Wang, H.; Kong, J.; Shi, F.; Zhang, Y.H.; Wang, X.L. Preparation, structure, DNA-binding properties, and antioxidant activities of a homodinuclear erbium(III) complex with a pentadentate Schiff base ligand. J. Chem. Res. 2014, 38, 211–217. [Google Scholar] [CrossRef]
  3. Sun, Y.X.; Zhang, S.T.; Ren, Z.L.; Dong, X.Y.; Wang, L. Synthesis, characterization, and crystal structure of a new supramolecular CdII complex with halogen-substituted salen-type bisoxime. Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 2013, 43, 995–1000. [Google Scholar] [CrossRef]
  4. Song, X.Q.; Liu, P.P.; Liu, Y.A.; Zhou, J.J.; Wang, X.L. Two dodecanuclear heterometallic [Zn6Ln6] clusters constructed by a multidentate salicylamide salen-like ligand: Synthesis, structure, luminescence and magnetic properties. Dalton Trans. 2016, 45, 8154–8163. [Google Scholar] [CrossRef] [PubMed]
  5. Xu, L.; Zhu, L.C.; Ma, J.C.; Zhang, Y.; Zhang, J.; Dong, W.K. Syntheses, structures and spectral properties of mononuclear CuII and dimeric ZnII complexes an asymmetric Salamo-type N2O2 ligand. Zeitschrift für Anorganische und Allgemeine Chemie 2015, 641, 2520–2524. [Google Scholar] [CrossRef]
  6. Wang, P.; Zhao, L. Synthesis and crystal structure of supramolecular copper(II) complex N2O2 coordination Sphere. Asian J. Chem. 2015, 4, 1424–1426. [Google Scholar] [CrossRef]
  7. Sun, Y.X.; Wang, L.; Dong, X.Y.; Ren, Z.L.; Meng, W.S. Synthesis, characterization, and crystal structure of a supramolecular CoII complex containing Salen-type bisoxime. Synth. React. Inorg. Met-Org. Nano-Met. Chem. 2013, 43, 599–603. [Google Scholar] [CrossRef]
  8. Wu, H.L.; Bai, Y.C.; Zhang, Y.H.; Pan, G.L.; Kong, J.; Shi, F.; Wang, X.L. Two lanthanide(III) complexes the schiff base N,N-Bis(salicylidene)-1,5-diamino-3-oxapentane: Synthesis, characterization, DNA-binding properties, and antioxidation. Zeitschrift für Anorganische und Allgemeine Chemie 2014, 640, 2062–2071. [Google Scholar] [CrossRef]
  9. Wu, H.L.; Bai, Y.; Yuan, J.K.; Wang, H.; Pan, G.L.; Fan, X.Y.; Kong, J. A zinc(II) complex with tris(2-(N-methyl)benzimidazlylmethyl)amine and salicylate: Synthesis, crystal structure, and DNA-binding. J. Coord. Chem. 2012, 65, 2839–2851. [Google Scholar] [CrossRef]
  10. Chen, C.Y.; Zhang, J.W.; Zhang, Y.H.; Yang, Z.H.; Wu, H.L. Gadolinium(III) and dysprosium(III) complexes with a Schiff base bis(N-salicylidene)-3-oxapentane-1,5-diamine: Synthesis, characterization, antioxidation, and DNA-binding studies. J. Coord. Chem. 2015, 68, 1054–1071. [Google Scholar] [CrossRef]
  11. Wang, F.; Gao, L.; Zhao, Q.; Zhang, Y.; Dong, W.K.; Ding, Y.J. A highly selective fluorescent chemosensor for CN- a novel bis(salamo)-type tetraoxime ligand. Spectrochim. Acta Part A 2018, 190, 111–115. [Google Scholar] [CrossRef] [PubMed]
  12. Dong, X.Y.; Li, X.Y.; Liu, L.Z.; Zhang, H.; Ding, Y.J.; Dong, W.K. Tri- and hexanuclear heterometallic Ni(II)–M(II) (M = Ca, Sr and Ba) bis(salamo)-type complexes: Synthesis, structure and fluorescence properties. RSC Adv. 2017, 7, 48394–48403. [Google Scholar] [CrossRef]
  13. Wu, H.L.; Wang, C.P.; Wang, F.; Peng, H.P.; Zhang, H.; Bai, Y.C. A new manganese(III) complex from bis(5-methylsalicylaldehyde)-3-oxapentane-1,5-diamine: Synthesis, characterization, antioxidant activity and luminescence. J. Chin. Chem. Soc. 2015, 62, 1028–1034. [Google Scholar] [CrossRef]
  14. Dong, W.K.; Ma, J.C.; Zhu, L.C.; Zhang, Y. Self-assembled zinc(II)-lanthanide(III) heteromultinuclear complexes constructed from 3-MeOsalamo ligand: Syntheses, structures and luminescent properties. Cryst. Growth Des. 2016, 16, 6903–6914. [Google Scholar] [CrossRef]
  15. Song, X.Q.; Peng, Y.J.; Chen, G.Q.; Wang, X.R.; Liu, P.P.; Xu, W.Y. Substituted group-directed assembly of Zn(II) coordination complexes two new structural related pyrazolone Salen ligands: Syntheses, structures and fluorescence properties. Inorg. Chim. Acta 2015, 427, 13–21. [Google Scholar] [CrossRef]
  16. Dong, W.K.; Zhang, F.; Li, N.; Xu, L.; Zhang, Y.; Zhang, J.; Zhu, L.C. Trinuclear cobalt(II) and zinc(II) salamo–type complexes: Syntheses, crystal structures, and fluorescent properties. Zeitschrift für Anorganische und Allgemeine Chemie 2016, 642, 532–538. [Google Scholar] [CrossRef]
  17. Song, X.Q.; Cheng, G.Q.; Liu, Y.A. Enhanced Tb(III) luminescence by d10 transition metal coordination. Inorg. Chim. Acta 2016, 450, 386–394. [Google Scholar] [CrossRef]
  18. Dong, W.K.; Ma, J.C.; Zhu, L.C.; Zhang, Y. Nine self–assembled nickel(II)–lanthanide(III) heterometallic complexes constructed from a Salamo–type bisoxime and bearing N- or O-donor auxiliary ligand: Syntheses, structures and magnetic properties. New J. Chem. 2016, 40, 6998–7010. [Google Scholar] [CrossRef]
  19. Song, X.Q.; Liu, P.P.; Xiao, Z.R.; Li, X.; Liu, Y.A. Four polynuclear complexes a versatile salicylamide salen-like ligand: Synthesis, structural variations and magnetic properties. Inorg. Chim. Acta 2015, 438, 232–244. [Google Scholar] [CrossRef]
  20. Dong, W.K.; Ma, J.C.; Dong, Y.J.; Zhu, L.C.; Zhang, Y. Di-and tetranuclear heterometallic 3d-4f cobalt(II)-lanthanide(III) complexes derived from a hexadentate bisoxime: Syntheses, structures and magnetic properties. Polyhedron 2016, 115, 228–235. [Google Scholar] [CrossRef]
  21. Liu, P.P.; Wang, C.Y.; Zhang, M.; Song, X.Q. Pentanuclear sandwich-type ZnII-LnIII clusters a new Salen-like salicylamide ligand: Structure, near-infrared emission and magnetic properties. Polyhedron 2017, 129, 133–140. [Google Scholar] [CrossRef]
  22. Wu, H.L.; Pan, G.L.; Wang, H.; Wang, X.L.; Bai, Y.C.; Zhang, Y.H. Study on synthesis, crystal structure, antioxidant and DNA-binding of mono-, di- and poly-nuclear lanthanides complexes with bis(N-salicylidene)-3-oxapentane-1,5-diamine. J. Photochem. Photobiol. B Biol. 2014, 135, 33–43. [Google Scholar] [CrossRef] [PubMed]
  23. Dong, W.K.; Zhang, J.; Zhang, Y.; Li, N. Novel multinuclear transition metal(II) complexes an asymmetric Salamo-type ligand: Syntheses, structure characterizations and fluorescent properties. Inorg. Chim. Acta 2016, 444, 95–102. [Google Scholar] [CrossRef]
  24. Dong, Y.J.; Li, X.L.; Zhang, Y.; Dong, W.K. A highly selective visual and fluorescent sensor for Pb2+ and Zn2+ and crystal structure of Cu2+ complex-on a novel single-armed Salamo-type bisoxime. Supramol. Chem. 2017, 29, 518–527. [Google Scholar] [CrossRef]
  25. Sun, Y.X.; Xu, L.; Zhao, T.H.; Liu, S.H.; Liu, G.H.; Dong, X.T. Synthesis and crystal structure of a 3D supramolecular copper(II) complex with 1-(3-{[(E)-3-bromo-5-chloro-2-hydroxybenzylidene]amino}phenyl) ethanone oxime. Synth. React. Inorg. Met.-Org. Nano-Met. Chem. 2013, 43, 509–513. [Google Scholar] [CrossRef]
  26. Dong, W.K.; Wang, Z.K.; Li, G.; Zhao, M.M.; Dong, X.Y.; Liu, S.H. Syntheses, crystal structures, and properties of a Salamo-type tetradentate chelating ligand and its pentacoordinated copper(II) complex. Zeitschrift für Anorganische und Allgemeine Chemie 2013, 639, 2263–2268. [Google Scholar] [CrossRef]
  27. Akine, S.; Dong, W.K.; Nabeshima, T. Octanuclear zinc(II) and cobalt(II) clusters produced by cooperative tetrameric assembling of oxime chelate ligands. Inorg. Chem. 2006, 454, 677–4684. [Google Scholar] [CrossRef] [PubMed]
  28. Dong, W.K.; Zhang, X.Y.; Zhao, M.M.; Li, G.; Dong, X.Y. Syntheses and crystal structures of 5-Methoxy-6′-hydroxy-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol and its tetranuclear zinc(II) complex. Chin. J. Inorg. Chem. 2014, 30, 710–716. [Google Scholar]
  29. Akine, S.; Taniguchi, T.; Dong, W.K.; Masubuchi, S.; Nabeshima, T. Oxime-Based Salen-Type Tetradentate Ligands with High Stability against Imine Metathesis Reaction. J. Org. Chem. 2005, 70, 1704–1711. [Google Scholar] [CrossRef] [PubMed]
  30. Dong, W.K.; Li, X.L.; Wang, L.; Zhang, Y.; Ding, Y.J. A new application of Salamo-type bisoximes: As a relay-sensor for Zn2+/Cu2+ and its novel complexes for successive sensing of H+/OH. Sens. Actuators B Chem. 2016, 229, 370–378. [Google Scholar] [CrossRef]
  31. Wang, L.; Ma, J.C.; Dong, W.K.; Zhu, L.C.; Zhang, Y. A novel Self–assembled nickel(II)–cerium(III) heterotetranuclear dimer constructed from N2O2-type bisoxime and terephthalic acid: Synthesis, structure and photophysical properties. Zeitschrift für Anorganische und Allgemeine Chemie 2016, 642, 834–839. [Google Scholar] [CrossRef]
  32. Dong, W.K.; Li, G.; Wang, Z.K.; Dong, X.Y. A novel trinuclear cobalt(II) complex derived from an asymmetric Salamo-type N2O3 bisoxime chelate ligand: Synthesis, structure and optical properties. Spectrochim. Acta Part A 2014, 133, 340–347. [Google Scholar] [CrossRef] [PubMed]
  33. Akine, S.; Morita, Y.; Utsuno, F.; Nabeshima, T. Multiple folding structures mediated by metal coordination of acyclic multidentate ligand. Inorg. Chem. 2009, 48, 10670–10678. [Google Scholar] [CrossRef] [PubMed]
  34. Wang, B.J.; Dong, W.K.; Zhang, Y.; Akogun, S.F. A novel relay-sensor for highly sensitive and selective detection of Zn2+/Pic and fluorescence on/off switch response of H+/OH. Sens. Actuators B Chem. 2017, 247, 254–264. [Google Scholar] [CrossRef]
  35. Dong, W.K.; Zhang, L.S.; Sun, Y.X.; Zhao, M.M.; Li, G.; Dong, X.Y. Synthesis, crystal structure and spectroscopic properties of a supramolecular zinc(II) complex with N2O2 coordination sphere. Spectrochim. Acta Part A 2014, 121, 324–329. [Google Scholar] [CrossRef] [PubMed]
  36. Hao, J.; Li, L.H.; Zhang, J.T.; Akogun, S.F.; Wang, L.; Dong, W.K. Four homo- and hetero-bismetallic 3d/3d-2s complexes constructed from a naphthalenediol-based acyclic bis(salamo)-type tetraoxime ligand. Polyhedron 2017, 134, 1–10. [Google Scholar] [CrossRef]
  37. Chen, L.; Dong, W.K.; Zhang, H.; Zhang, Y.; Sun, Y.X. Structural variation and luminescence properties of tri- and dinuclear CuII and ZnII complexes constructed from a naphthalenediol-based bis(Salamo)-type ligand. Cryst. Growth Des. 2017, 17, 3636–3648. [Google Scholar] [CrossRef]
  38. Dong, W.K.; Ma, J.C.; Dong, Y.J.; Zhao, L.; Zhu, L.C.; Sun, Y.X.; Zhang, Y. Two hetero-trinuclear Zn(II)-M(II) (M = Sr, Ba) complexes metallohost of mononuclear Zn(II) complex: Syntheses, structures and fluorescence properties. J. Coord. Chem. 2016, 69, 3231–3241. [Google Scholar] [CrossRef]
  39. Dong, Y.J.; Dong, X.Y.; Dong, W.K.; Zhang, Y.; Zhang, L.S. Three asymmetric Salamo-type copper(II) and cobalt(II) complexes: Syntheses, structures, fluorescent properties. Polyhedron 2017, 123, 305–315. [Google Scholar] [CrossRef]
  40. Dong, Y.; Li, F.J.; Jiang, X.X.; Song, F.Y.; Cheng, Y.X.; Zhu, C.J. Na+ triggered fluorescence sensors for Mg2+ detection a coumarin salen moiety. Org. Lett. 2011, 9, 2252–2255. [Google Scholar] [CrossRef] [PubMed]
  41. Madison, W.I. SAINT-Plus, Bruker Analytical X-ray System; Bruker: Billerica, MA, USA, 1999. [Google Scholar]
  42. Sheldrick, G.M. SADABS, Program for Empirical Absorption Correction of Area Detector Data; University of Gottingen: Gottingen, Germany, 1996. [Google Scholar]
  43. Sheldrick, G.M. SHELXS-97, Program for the Solution and the Refinement of Crystal Structures; University of Gottingen: Gottingen, Germany, 1997. [Google Scholar]
  44. Gao, L.; Wang, F.; Zhao, Q.; Zhang, Y.; Dong, W.K. Mononuclear Zn(II) and trinuclear Ni(II) complexes derived from a coumarin-containing N2O2 ligand: Syntheses, crystal structures and fluorescence properties. Polyhedron 2018, 139, 7–16. [Google Scholar] [CrossRef]
  45. Dong, X.Y.; Akogun, S.F.; Zhou, W.M.; Dong, W.K. Tetranuclear Zn(II) complex an asymmetrical Salamo-type chelating ligand: Synthesis, structural characterization, and fluorescence property. J. Chin. Chem. Soc. 2017, 64, 412–419. [Google Scholar] [CrossRef]
  46. Dong, W.K.; Lan, P.F.; Zhou, W.M.; Zhang, Y. Salamo-type trinuclear and tetranuclear cobalt(II) complexes a new asymmetry salamo-type ligand: Syntheses, crystal structures and fluorescence properties. J. Coord. Chem. 2016, 65, 1272–1283. [Google Scholar] [CrossRef]
  47. Li, L.H.; Dong, W.K.; Zhang, Y.; Akogun, S.F.; Xu, L. Syntheses, structures and catecholase activities of homo-and hetero-trinuclear cobalt(II) complexes constructed from an acyclic naphthalenediol-based bis(salamo)-type ligand. Appl. Organomet. Chem. 2017, 31. [Google Scholar] [CrossRef]
  48. Dong, W.K.; Akogun, S.F.; Zhang, Y.; Dong, X.Y. A reversible “turn-on” fluorescent sensor for selective detection of Zn2+. Sens. Actuators B Chem. 2017, 238, 723–734. [Google Scholar] [CrossRef]
  49. Ma, J.C.; Dong, X.Y.; Dong, W.K.; Zhang, Y.; Zhu, L.C.; Zhang, J.T. An unexpected dinuclear Cu(II) complex with a bis(Salamo) chelating ligand: Synthesis, crystal structure, and photophysical properties. J. Coord. Chem. 2016, 69, 149–159. [Google Scholar] [CrossRef]
  50. Zhang, Y.G.; Shi, Z.H.; Yang, L.Z.; Tang, X.L.; An, Y.Q.; Ju, Z.H.; Liu, W.S. A facile fluorescent probe coumarin-derived Schiff base for Al3+ in aqueous media. Inorg. Chem. Commun. 2014, 39, 86–89. [Google Scholar] [CrossRef]
  51. Yang, L.; Powell, D.R.; House, R.P. Structural variation in copper(I) complexes with pyridylmethylamide ligands: Structural analysis with a new four-coordinate geometry index, τ4. Dalton Trans. 2007, 9, 955–964. [Google Scholar] [CrossRef] [PubMed]
  52. Wu, H.L.; Bai, Y.C.; Zhang, Y.H.; Li, Z.; Wu, M.C.; Chen, C.Y.; Zhang, J.W. Synthesis, crystal structure, antioxidation and DNA-binding properties of a dinuclear copper(II) complex with bis(N-salicylidene)-3-oxapentane-1,5-diamine. J. Coord. Chem. 2014, 67, 3054–3066. [Google Scholar] [CrossRef]
  53. Zheng, S.S.; Dong, W.K.; Zhang, Y.; Chen, L.; Dong, Y.G. Four Salamo-type 3d–4f hetero-bimetallic [ZnIILnIII] complexes: Syntheses, crystal structures, and luminescent and magnetic properties. New J. Chem. 2017, 41, 4966–4973. [Google Scholar] [CrossRef]
  54. Chai, L.Q.; Huang, J.J.; Zhang, J.Y.; Li, Y.X. Two 1-D and 2-D cobalt(II) complexes: Synthesis, crystal structures, spectroscopic and electrochemical properties. J. Coord. Chem. 2015, 68, 1224–1237. [Google Scholar] [CrossRef]
  55. Addison, A.W.; Rao, T.N.; Reedijk, J.; Rijn, J.V.; Verschoor, G.C. Synthesis, structure, and spectroscopic properties of copper(II) compounds containing nitrogen–sulphur donor ligands; the crystal and molecular structure of aqua[1,7-bis(N-methylbenzimidazol-2′-yl)-2,6-dithiaheptane]copper(II) perchlorate. J. Chem. Soc. Dalton Trans. 1984, 7, 1349–1356. [Google Scholar] [CrossRef]
  56. Li, X.Y.; Chen, L.; Gao, L.; Zhang, Y.; Akogun, S.F.; Dong, W.K. Syntheses, crystal structures and catalytic activities of two solvent-induced homotrinuclear Co(II) complexes with a naphthalenediol-based bis(Salamo)-type tetraoxime ligand. RSC Adv. 2017, 7, 35905–35916. [Google Scholar] [CrossRef]
  57. Tao, C.H.; Ma, J.C.; Zhu, L.C.; Zhang, Y.; Dong, W.K. Heterobimetallic 3d–4f Zn(II)–Ln(III) (Ln = Sm, Eu, Tb and Dy) complexes with a N2O4 bisoxime chelate ligand and a simple auxiliary ligand Py: Syntheses, structures and luminescence properties. Polyhedron 2017, 128, 38–45. [Google Scholar] [CrossRef]
  58. Wu, H.L.; Pan, G.L.; Bai, Y.C.; Wang, H.; Kong, J. Synthesis, structure, antioxidation, and DNA-bindingstudies of a binuclear ytterbium(III) complex with bis(N-salicylidene)-3-oxapentane-1,5-diamine. Res. Chem. Intermed. 2015, 41, 3375–3388. [Google Scholar] [CrossRef]
  59. Dong, W.K.; Ma, J.C.; Zhu, L.C.; Zhang, Y.; Li, X.L. Four new nickel(II) complexes an asymmetric Salamo-type ligand: Synthesis, structure, solvent effect and electrochemical property. Inorg. Chim. Acta 2016, 445, 140–148. [Google Scholar] [CrossRef]
  60. Liu, Y.A.; Wang, C.Y.; Zhang, M.; Song, X.Q. Structures and magnetic properties of cyclic heterometallic tetranuclear clusters. Polyhedron 2017, 127, 278–286. [Google Scholar] [CrossRef]
  61. Liu, P.P.; Sheng, L.; Song, X.Q.; Xu, W.Y.; Liu, Y.A. Synthesis, structure and magnetic properties of a new one dimensional manganese coordination polymer constructed by a new asymmetrical ligand. Inorg. Chim. Acta 2015, 434, 252–257. [Google Scholar] [CrossRef]
  62. Wang, L.; Li, X.Y.; Zhao, Q.; Li, L.H.; Dong, W.K. Fluorescence properties of heterotrinuclear Zn(II)–M(II) (M = Ca, Sr and Ba) bis(salamo)-type complexes. RSC Adv. 2017, 7, 48730–48737. [Google Scholar] [CrossRef]
  63. Zhang, H.; Dong, W.K.; Zhang, Y.; Akogun, S.F. Naphthalenediol-based bis(Salamo)-type homo- and heterotrinuclear cobalt(II) complexes: Syntheses, structures and magnetic properties. Polyhedron 2017, 133, 279–293. [Google Scholar] [CrossRef]
  64. Dong, X.Y.; Gao, L.; Wang, F.; Li, X.Y.; Zhang, Y.; Dong, W.K. Tri- and mono-nuclear zinc(II) complexes half- and mono-Salamo chelating ligands. Crystals 2017, 7, 267. [Google Scholar] [CrossRef]
  65. Wang, L.; Hao, J.; Zhai, L.X.; Zhang, Y.; Dong, W.K. Synthesis, crystal structure, luminescence, electrochemical and antimicrobial properties of bis(salamo)-based co(II) complex. Crystals 2017, 7, 277. [Google Scholar] [CrossRef]
  66. Chohan, Z.H.; Arif, M.; Sarfraz, M. Metal-based antibacterial and antifungal amino acid derived Schiff bases: Their synthesis, characterization and in vitro biological activity. Appl. Organomet. Chem. 2007, 21, 294–302. [Google Scholar] [CrossRef]
Scheme 1. Synthetic route to H2L.
Scheme 1. Synthetic route to H2L.
Crystals 08 00077 sch001
Figure 1. The FT-IR spectra of H2L and its complexes 1, 2 and 3 (cm−1).
Figure 1. The FT-IR spectra of H2L and its complexes 1, 2 and 3 (cm−1).
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Figure 2. The UV-VIS spectra of H2L and its complexes 1, 2 and 3 (cm−1).
Figure 2. The UV-VIS spectra of H2L and its complexes 1, 2 and 3 (cm−1).
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Figure 3. Emission spectra of H2L and its complexes 1, 2 and 3 in dichloromethane (2.5 × 10−5 M) upon excitation at 351 nm.
Figure 3. Emission spectra of H2L and its complexes 1, 2 and 3 in dichloromethane (2.5 × 10−5 M) upon excitation at 351 nm.
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Figure 4. (a) X-ray crystal structure and atom numbering of complex 1 with 30% probability displacement ellipsoids; (b) Coordination polyhedron of Cu(II) atom of complex 1.
Figure 4. (a) X-ray crystal structure and atom numbering of complex 1 with 30% probability displacement ellipsoids; (b) Coordination polyhedron of Cu(II) atom of complex 1.
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Figure 5. (a) View of the dihedral angles between the benzene rings and the N2O2 basal plane of complex 1; (b) View of the dihedral angles between planes CuN2 and CuO2 of complex 1.
Figure 5. (a) View of the dihedral angles between the benzene rings and the N2O2 basal plane of complex 1; (b) View of the dihedral angles between planes CuN2 and CuO2 of complex 1.
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Figure 6. View of the three-dimensional supra-molecular structure of complex 1 showing the C-H···O, C-H···Cl hydrogen bondings.
Figure 6. View of the three-dimensional supra-molecular structure of complex 1 showing the C-H···O, C-H···Cl hydrogen bondings.
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Figure 7. (a) X-ray crystal structure and atom numbering of complex 2 with 30% probability displacement ellipsoids; (b) Coordination polyhedron for Co(II) atom of complex 2.
Figure 7. (a) X-ray crystal structure and atom numbering of complex 2 with 30% probability displacement ellipsoids; (b) Coordination polyhedron for Co(II) atom of complex 2.
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Figure 8. (a) View of the dihedral angles between the benzene rings and the N2O2 basal plane of complex 2; (b) View of the dihedral angles between the planes CoN2 and CoO2 of complex 2.
Figure 8. (a) View of the dihedral angles between the benzene rings and the N2O2 basal plane of complex 2; (b) View of the dihedral angles between the planes CoN2 and CoO2 of complex 2.
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Figure 9. View of the three-dimensional supra-molecular structure of complex 2 exhibiting the C-H···O, O-H···O, C-H···Cl hydrogen bondings and C-Cl···π stacking interactions.
Figure 9. View of the three-dimensional supra-molecular structure of complex 2 exhibiting the C-H···O, O-H···O, C-H···Cl hydrogen bondings and C-Cl···π stacking interactions.
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Figure 10. (a) X-ray crystal structure and atom numbering of complex 3 with 30% probability displacement ellipsoids; (b) Coordination polyhedrons for Ni(II) atoms of complex 3.
Figure 10. (a) X-ray crystal structure and atom numbering of complex 3 with 30% probability displacement ellipsoids; (b) Coordination polyhedrons for Ni(II) atoms of complex 3.
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Figure 11. (a) View of the dihedral angles between the benzene rings and the N2O2 basal plane of complex 3; (b) View of the dihedral angles between the planes NiN2 and NiO2 of complex 3.
Figure 11. (a) View of the dihedral angles between the benzene rings and the N2O2 basal plane of complex 3; (b) View of the dihedral angles between the planes NiN2 and NiO2 of complex 3.
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Figure 12. Intra-molecular C-H···O and C-H···N hydrogen bonds of complex 3.
Figure 12. Intra-molecular C-H···O and C-H···N hydrogen bonds of complex 3.
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Figure 13. View of the two-dimensional supra-molecular structure of complex 3 exhibiting the O-H···O, C-H···O hydrogen bonding interactions.
Figure 13. View of the two-dimensional supra-molecular structure of complex 3 exhibiting the O-H···O, C-H···O hydrogen bonding interactions.
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Figure 14. The diameter of inhibition zones of E. coli in different concentrations.
Figure 14. The diameter of inhibition zones of E. coli in different concentrations.
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Figure 15. The diameter of inhibition zones of S. aureus in different concentrations.
Figure 15. The diameter of inhibition zones of S. aureus in different concentrations.
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Table 1. Crystal data and refinement parameters for complexes 1, 2 and 3.
Table 1. Crystal data and refinement parameters for complexes 1, 2 and 3.
Complex123
FormulaC25H19Cl3CuN2O8C26H23Cl3CoN2O9C64H54N4Ni3O22
Formula weight645.31672.741407.24
Temperature (K)296(2)173.00(10)153(2)
Wavelength (Å)0.710730.710730.71073
Crystal systemMonoclinicMonoclinicTriclinic
Space groupP21/cP21/cP–1
Unit cell dimensions
a (Å)13.5401(9)12.1129(5)12.6250(18)
b (Å)6.8318(5)13.5779(3)12.6344(17)
c (Å)27.1822(16)16.7455(6)14.7046(18)
α (°)9090113.420(4)
β (°)94.8504(19)100.038(3)95.978(5)
γ (°)9090107.557(2)
V3)2505.4(3)2711.93(15)1983.6(5)
Z441
Dc (g cm−3)1.7111.6481.178
μ (mm−1)1.2470.9870.770
F (000)13081372726
Crystal size (mm)0.26 × 0.22 × 0.190.16 × 0.07 × 0.040.22 × 0.19 × 0.18
θ Range (°)2.219–25.0053.416–26.0201.750–25.010
−16 ≤ h ≤ 16,−9 ≤ h ≤ 14,−13 ≤ h ≤ 15
Index ranges−8 ≤ k ≤ 6−16 ≤ k ≤ 15−15 ≤ k ≤ 15
−32 ≤ l ≤ 31−20 ≤ l ≤ 20−17 ≤ l ≤ 16
Reflections collected163851065514781
Independent reflections440253436919
Rint0.07460.04100.0661
Completeness99.9%99.7%99.0%
Data/restraints/parameters4402/0/3545343/4/3766919/69/319
GOF1.0971.0531.050
Final R1, wR2 indices0.0659, 0.10660.0585, 0.13150.0579, 0.1580
R1, wR2 indices (all data)0.1058, 0.12070.0861, 0.15300.0890, 0.1779
Largest differences0.364/−0.4391.211/−0.6530.935/−0.828
peak and hole (e Å−3)
Table 2. The major FT-IR spectra of H2L and its complexes 1, 2 and 3 (cm−1).
Table 2. The major FT-IR spectra of H2L and its complexes 1, 2 and 3 (cm−1).
Compoundν(C=N)ν(Ar-O)ν(C=O)ν(C=C)
H2L1616128217341386
Complex 11601124217221320
Complex 21597123817261312
Complex 31605122217191325
Table 3. Absorption maxima and molar extinction coefficients for H2L and its complexes 1, 2 and 3.
Table 3. Absorption maxima and molar extinction coefficients for H2L and its complexes 1, 2 and 3.
Compoundλmax1, nmεmax1, M−1·cm−1λmax2, nmεmax2, M−1·cm−1λmax3, nmεmax3, M−1·cm−1
H2L2914.9 × 10−43303.3 × 10−43452.9 × 10−4
Complex 12992.5 × 10−43432.7 × 10–43960.7 × 10−4
Complex 22973.2 × 10−43473.9 × 10−43990.9 × 10−4
Complex 33384.3 × 10−43910.7 × 10−4
Table 4. Selected bond lengths (Å) and angles (°) for complex 1.
Table 4. Selected bond lengths (Å) and angles (°) for complex 1.
Bond
Cu1-O11.891(3)Cu1-N11.950(4)
Cu1-O21.909(3)Cu1-N21.976(4)
Angles
O1-Cu1-O283.86(14)O1-Cu1-N290.30(15)
O1-Cu1-N1162.19(18)O2-Cu1-N2161.44(17)
O2-Cu1-N189.28(15)N1-Cu1-N2100.99(16)
Table 5. Hydrogen bondings (Å, °) for complex 1.
Table 5. Hydrogen bondings (Å, °) for complex 1.
D-H · AD · AD-H · A
C10-H10 · O42.724(6)103
C13-H13 · O72.715(5)103
C12-H12B · O13.495(6)156
C20-H20 · O33.284(6)133
C25-H25 · O83.071(7)141
C12-H12A · Cl13.561(6)136
Table 6. Selected bond lengths (Å) and angles (°) for complex 2.
Table 6. Selected bond lengths (Å) and angles (°) for complex 2.
Bond
Co1-O12.008(3)Co1-N12.014(3)
Co1-O61.926(3)Co1-N22.150(3)
Co1-O92.039(3)
Angles
O1-Co1-O990.67(12)O6-Co1-N1124.97(14)
O1-Co1-N188.52(12)O6-Co1-N286.65(12)
O1-Co1-N2178.25(13)O9-Co1-N291.00(13)
O6-Co1-O193.23(11)N1-Co1-O9124.07(14)
O6-Co1-O9110.91(13)N1-Co1-N290.12(12)
Table 7. Hydrogen bondings (Å, °) for complex 2.
Table 7. Hydrogen bondings (Å, °) for complex 2.
D-H···AD···AD-H···A
C10-H10···O32.682(4)104
C13-H13A···O93.433(6)145
C14-H14···O72.712(5)103
C25-H25A···O13.041(7)125
O9-H9···O22.651(4)166
C6-H6···O63.315(4)139
C13-H13B···O23.309(5)134
C26-H26···O83.146(6)156
C25-H25C···Cl33.642(6)159
D-X···AD-XX···AD···AD-X···A
C26-Cl1···Cg61.757(5)3.8244.415(5)97.59
C26-Cl2···Cg61.757(5)3.8494.415(5)96.78
C26-Cl2···Cg41.757(5)3.6554.557(5)109.67
Note: Cg6 = C15–C16–C17–C18–C20–C23; Cg4 = O7–C19–C23.
Table 8. Selected bond lengths (Å) and angles (°) for complex 3.
Table 8. Selected bond lengths (Å) and angles (°) for complex 3.
Bond
Ni1-O32.082(3)Ni2-O32.014(3)
Ni1-O3#2.082(3)Ni2-O62.150(3)
Ni1-O82.031(3)Ni2-O72.018(3)
Ni1-O8#2.031(3)Ni2-O92.040(3)
Ni1-O9#2.089(3)Ni2-N12.068(4)
Ni1-O92.089(3)Ni2-N22.069(4)
Angles
O3-Ni1-O3#180.0O3-Ni2-O693.13(12)
O3#-Ni1-O9101.51(11)O3-Ni2-O980.97(11)
O3-Ni1-O9#101.51(11)O3-Ni2-N187.44(13)
O3-Ni1-O978.49(11)O7-Ni2-O390.35(13)
O3#-Ni1-O9#78.49(11)O7-Ni2-O6175.38(11)
O8#-Ni1-O3#90.07(12)O7-Ni2-O994.69(12)
O8#-Ni1-O389.93(12)O7-Ni2-N191.74(15)
O8-Ni1-O3#89.93(12)O7-Ni2-N290.06(15)
O8-Ni1-O390.07(12)O9-Ni2-O688.86(12)
O8#-Ni1-O8180.0O9-Ni2-N1166.76(13)
O8#-Ni1-O9#88.56(12)O9-Ni2-N285.38(13)
O8-Ni1-O988.56(12)N1-Ni2-O685.38(14)
O8#-Ni1-O991.44(12)N1-Ni2-N2106.20(14)
O8-Ni1-O9#91.44(12)N2-Ni2-O687.29(15)
O9#-Ni1-O9180.0
Table 9. Hydrogen bondings (Å, °) for complex 3.
Table 9. Hydrogen bondings (Å, °) for complex 3.
D-H···AD···AD-H···A
C8-H8···O83.176(6)122
C8-H8···O93.289(5)133
C11-H11···O22.661(6)103
C12-H12B···N22.878(9)102
C13-H13B···O73.110(8)142
C14-H14···O102.673(6)101
C32-H32C···O83.362(6)155
O6-H6···O12.741(5)164
C12-H12A···O113.180(8)154

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Gao, L.; Liu, C.; Wang, F.; Dong, W.-K. Tetra-, Penta- and Hexa-Coordinated Transition Metal Complexes Constructed from Coumarin-Containing N2O2 Ligand. Crystals 2018, 8, 77. https://doi.org/10.3390/cryst8020077

AMA Style

Gao L, Liu C, Wang F, Dong W-K. Tetra-, Penta- and Hexa-Coordinated Transition Metal Complexes Constructed from Coumarin-Containing N2O2 Ligand. Crystals. 2018; 8(2):77. https://doi.org/10.3390/cryst8020077

Chicago/Turabian Style

Gao, Lei, Chang Liu, Fei Wang, and Wen-Kui Dong. 2018. "Tetra-, Penta- and Hexa-Coordinated Transition Metal Complexes Constructed from Coumarin-Containing N2O2 Ligand" Crystals 8, no. 2: 77. https://doi.org/10.3390/cryst8020077

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