| Salen-type ligands and their derivatives have an important position in the field of moderncoordination chemistry as a kind of tetradentate ligands. They have unique properties andvarious structure, for example, they can be used as models of reaction centers ofmetalloenzymes, catalysts for organic reactions, nonlinear optical materials, and they can alsobe applied to the fields such as analytical chemistry, magnetism and biochemistry and so on.A lot of Salen-type ligands and their complexes with symmetrical structure have beenreported and studied, which have the excellent coordination ability to react with metal ionsgenerating stable complexes. But the Salen-type compounds with asymmetrical structure arerelatively rare. Electronic and steric effect of the ligands may be effectively controlled byintroduction of different substituents into the two benzene rings. The asymmetricalconfiguration can afford more opportunities of a greater structural variation and infinitecoordination polymers, which could be expected to lead to novel characteristics and betterenantioselectivities when compared with their symmetrical counterparts. Therefore, thedesign and synthesis of asymmetrical Salamo-type compounds have the importantsignificance, which are as a kind of important Salen-type compounds. In addition, in order toeffectively control the supramolecular self-assembly, the introduction of different solventmolecules may also have an influence up on supramolecular structure to some extent.In this paper, four asymmetric Salamo-type ligands have been designed and synthesizedbased on1,2-bis(aminooxy)ethane and different salicylaldehyde derivatives. The ligands are:5-methoxy-4′-chloro-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L1),5-methoxy-4′,6′-dibromo-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H2L2),4-bromo-6’-hydroxy-2,2’-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H3L3) and5-methoxy-6′-hydroxy-2,2′-[ethylenedioxybis(nitrilomethylidyne)]diphenol (H3L4), whichwere characterized by IR, UV-Vis, fluorescence spectra and a series of physical and chemicalanalysis methods.A series of transition metal complexes have been designed and synthesized through thereaction of these ligands with Ni(OAc)2·4H2O, Co(OAc)2·4H2O, Cu(OAc)2·H2O andZn(OAc)2·2H2O, respectively. In nonaqueous solvents, the single crystals of two ligands andeight transition metal complexes have been obtained by means of naturally evaporation ofsolvents. They are H2L1, H3L4,[{NiL1(H2O)(μ-OAc)}2Ni]·H2O(1),[{NiL1(EtOH)(μ-OAc)}2Ni]·EtOH·H2O(2),[{NiL1(n-PrOH)(μ-OAc)}2Ni]·n-PrOH·H2O(3),2[{NiL1(n-butanol)(μ-OAc)}2Ni]·2n-butanol·H2O(4),[Co2(L2)2]·CH3COCH3(5),{[Cu2(L3’)2]n}(6),[Cu2(L4’)2](7),[{Zn2L4(CH3OH)(μ-OAc)}2](8), respectively. The structures of two ligands and eight complexes have been determined by X-ray single crystal diffractionmethod, the main crystal data are as following:H2L1: Empirical formula, C17H17ClN2O5, formula weight,364.78, Monoclinic, spacegroup: Pc, cell parameters: a=10.4013(13), b=4.5863(5), c=18.125(2), β=100.887(2)°, V=849.09(17)3, Z=2, R1=0.0675, wR2=0.1019;H3L4: Empirical formula, C17H18N2O6, formula weight,346.33, Monoclinic, space group:P2(1)/n, cell parameters: a=4.8429(4), b=10.2315(8), c=33.291(3), β=92.154(1)°,V=1648.4(2)3, Z=4, R1=0.0557, wR2=0.0740;complex1: Empirical formula, C38H44Cl2N4Ni3O18, formula weight,1091.80,Monoclinic, space group: P(2)1/c, cell parameters: a=10.8900(9), b=16.8501(15), c=15.1809(13), β=125.940(2)°, V=2255.4(3)3, Z=2, R1=0.0659, wR2=0.1351;complex2: Empirical formula, C46H62Cl2N4Ni3O20, formula weight,1238.03, Triclinic,space group: P-1, cell parameters: a=10.6150(9), b=11.9079(10), c=12.4401(11), α=75.6740(10)°, β=66.7070(10)°, γ=88.521(2)°, V=1394.8(2)3, Z=1, R1=0.0614, wR2=0.1405;complex3: Empirical formula, C50H72Cl2N4Ni3O20, formula weight,1296.15, Triclinic,space group: P-1, cell parameters: a=10.7360(9), b=12.2201(11), c=12.3969(12), α=102.6810(10)°, β=112.370(2)°, γ=90.4360(10)°, V=1459.8(2)3, Z=1, R1=0.0785,wR2=0.2039;complex4: Empirical formula, C154H212Cl6N12Ni9O54, formula weight,3836.45, Triclinic,space group: P-1, cell parameters: a=15.347(1), b=16.665(1), c=19.393(2), α=67.854(1)°, β=80.978(2)°, γ=73.714(1)°, V=4402.4(7)3, Z=1, R1=0.0965, wR2=0.2360;complex5: Empirical formula, C37H34Br4Co2N4O11, formula weight,1148.18,Monoclinic, space group: P2/c, cell parameters: a=9.1396(7), b=12.1249(14), c=19.0329(18), β=92.7780(10)°, V=2106.7(4)3, Z=2, R1=0.0753, wR2=0.1461;complex6: Empirical formula, C18H16Br2Cu2N2O6, formula weight,643.23, Triclinic,space group: P-1, cell parameters: a=5.3549(2), b=9.2637(8), c=11.2141(9), α=72.385(1)°, β=84.174(3)°, γ=76.304(1)°, V=514.86(6)3, Z=1, R1=0.0594, wR2=0.1518;complex7: Empirical formula, C20H22Cu2N2O8, formula weight,545.48, Monoclinic,space group: P2(1)/c, cell parameters: a=5.2234(5), b=15.317(2), c=12.976(1), β=100.294(1)°, V=1021.5(2)3, Z=2, R1=0.0348, wR2=0.0822;complex8: Empirical formula, C40H44N4O18Zn4, formula weight,1130.27, Triclinic,space group: P-1, cell parameters: a=8.0608(5), b=9.6381(7), c=16.4442(14), α= 73.476(1)°, β=86.947(2)°, γ=65.870(1)°, V=1114.88(14)3, Z=1, R1=0.0550, wR2=0.0822. |
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