Syntheses,Crystal Structures and Antibacterial Activities of Cobalt(Ⅱ) and Manganese(Ⅱ) Complexes with Schiff Base Ligand Derived from Tryptamine

Two new mononuclear complexes, namely Co(L)_2](1) and Mn(L)_2](2)(HL = N-(3-methylsalicylidene)tryptamine), have been synthesized by the reactions of the ligand with cobalt acetate or manganese acetate in anhydrous ethanol. The crystal structures of the complexes were characterized by IR spectrum, elemental analysis, PXRD and single-crystal X-ray diffraction analysis. Complex 1 crystallizes in monoclinic, space group C2/c, with a = 23.146(2), b = 9.4864(10), c = 13.9261(15) ?, β = 102.898(2)°, V = 2980.6(5) ?3, Z = 4, Dc = 1.367 g/cm3, F(000) = 1284 and μ = 0.616 mm-1. Complex 2 crystallizes in monoclinic, space group P21/n, with a = 14.807(11), b = 13.118(10), c = 16.663(13) ?, β = 111.237(14)°, V = 3017(4) ?3, Z = 4, Dc = 1.342 g/cm~3, F(000) = 1276 and μ = 0.477 mm-1. The units of complex 1 are linked by intermolecular N–H···π hydrogen bonds into infinite 1D chains, which are further extended into a 3D supramolecular structure by a series of π···π stacking interactions. The units of complex 2 are linked by intermolecular N–H···π hydrogen bonds and C–H···π hydrogen bonds into an infinite 3D supramolecular structure. Meanwhile, the antibacterial activities of the ligand and its complexes have been tested against four kinds of bacteria. The results show that the three compounds all have excellent antibacterial activities and that 1 and 2 possess stronger inhibiting effects against the bacteria than the Schiff base.