Two Rare Earth Complexes Based on Enoxacin: Synthesis, Crystal Structures, DNA Binding and Antibacterial Activities

Two rare earth complexes based on enoxacin (HEx), [Ce(Ex)(4)]center dot 39H(2)O (1) and [Sm-2(Ex)(4)(HEx)(2)(ox)]center dot 24H(2)O (2) (HEx=enoxacin; ox=oxalate), have been synthesized and characterized by IR, EA and X-ray diffraction. The analyses of the single X-ray diffraction results indicate that 1 is a mononuclear Ce(IV)) complex and crystallizes in tetragonal system, space group I4(1)/a with a=1.551 74(12) nm, c=4.066 6(4) nm, V=9.791 9(14) nm(3), Z=4, mu= 0.574 mm(-1), F (000)=4 480, D-c=1.441 g.cm(-3), R-1=0.074 3, wR(2)=0.180 0; 2 is an oxalate-bridged binuclear Sm(III) complex and crystallizes in triclinic system, space group P (1) over bar with a=1.505 72(19) urn, b=1.5 1 1 98(10) nm, c= 1.610 58(10) nm, alpha=116.723(2)degrees, beta=107.987(2)degrees, gamma=98.020(2)degrees, V=2.943 0(5) nm(3), Z=1, mu=1.095 mm(-1), F(000)= 1 412, D-c=1,545 g.cm(-3), R-1=0.039 4, wR(2)=0.121 7. The bindings of 1 and 2 with calf thymus DNA (CT-DNA) have been investigated by electronic absorption spectroscopy and emission spectroscopy. The results indicate that both complexes bind with double-stranded CT-DNA mostly via intercalative mode, with the intrinsic binding constants (K-b) of 4.45x10(4) and 6.56x10(4) mol(-1).L, respectively. Antibacterial tests show both complexes have better antibacterial activities against Gram and fungi microbial than the free ligand HEx. CCDC: 751128, 1; 751129, 2.