Synthesis and characterization of three heptaaza manganese(II) macrocyclic Schiff base complexes containing two 2-pyridylmethyl pendant arms

Transition Metal Chemistry (Impact Factor: 1.31). 04/2011; 36(3):307-311. DOI: 10.1007/s11243-011-9470-6


Three new Mn(II) bis(pendant arm)-macrocyclic Schiff base complexes, [MnLn]2+(n=1, 2, 3), have been prepared via cyclocondensation of 2,6-diacetylpyridine with three different branched hexadentate amines
(3,6-bis(2-pyridylmethyl)-3,6-diazaoctane-1,8-diamine (1), 3,7-bis(2-pyridylmethyl)-3,7-diazanonane-1,9-diamine (2) and 3,8-bis(2-pyridylmethyl)-3,8-diazadecane-1,10-diamine (3)) in the presence of MnCl2 in methanol. The ligands, L, are 15-, 16- and 17-membered pentaaza macrocycles having two 2-pyridylmethyl pendant arms [L1; 2,13-dimethyl-6,9-bis(2-pyridylmethyl)-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18), 2, 12, 14, 16-pentaene, L2; 2,14-dimethyl-6,10- bis(2-pyridylmethyl)-3,6,10,13,19-pentaazabicyclo[13.3.1]nonadeca-1(19), 2, 13, 15, 17-pentaene and
L3; 2,15-dimethyl-6,11-bis(2-pyridylmethyl)-3,6,11,14,20-pentaazabicyclo[14.3.1]eicosa-1(20),2,14,16,18-pentaene]. All the complexes
have been characterized by physicochemical and spectroscopic methods. The crystal structure of [MnL1](ClO4)2·CH3CN has been determined and indicates that in the solid state, the complex adopts a slightly distorted pentagonal bipyramidal
geometry with the Mn(II) centre located within a pentaaza macrocycle with two 2-pyridylmethyl pendants coordinating in the
axial positions.

Download full-text


Available from: Ahmad Ali Dehghani-Firouzabadi,
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: a b s t r a c t Two new branched pentadentate amines (N 5), 3,7-bis(2-pyridylmethyl)-5,5-dimethyl-3,7-diazaheptane-1-amine (1) and 4,8-bis(2-pyridylmethyl)-6,6-dimethyl-4,8-diaza octane-1-amine (2) have been pre-pared. These have been used to synthesis two new Schiff base complexes containing a pyridine and 2-pyridylmethyl pendant arm, by template [1+1] condensation of pyridine-2-carbaldehyde with the amines in the presence of Mn(II) in methanol. Elemental and spectral results are used to characterize the com-plexes and their structures are confirmed by single crystal X-ray diffraction studies. The structure of MnL 1 (ClO 4) 2 indicates that in the solid state the Mn(II) ion adopts a slightly distorted octahedral geom-etry. The crystal structure of [Ni(1)(MeCN)](ClO 4) 2 is also reported and exhibits a slightly distorted octa-hedral geometry. Also the synthesized complexes were screened for their antibacterial activity against Escherichia coli (Lio), Serratia marcescens (PTCC 1330), Staphylococcous aureus (ATCC 6633), and Proteus vulgaris (Lio) and results showed that the all complexes have antibacterial effects and [NiL 1 ](ClO 4) 2 , [MnL 2 ](ClO 4) and [MnL 1 ](ClO 4) 2 have more effective ones against E. coli.
    Polyhedron 04/2011; 30(11). DOI:10.1016/j.poly.2011.04.039 · 2.01 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Two new branched hexadentate amines, 4,8-bis(2-pyridylmethyl)-4,8-diazaundecane- 1,11-diamine (1) and 4,9-bis(2-pyridylmethyl)-4,9-diazadodecane-1,12-diamine (2) have been synthesized. Condensation with 2,6-diacetylpyridine in methanol in the presence of manganese(II), zinc(II) and cadmium(II) ions, leads to produce some new Schiff base macrocyclic complexes with two 2-pyridylmethyl pendant arms.The X-ray crystal structure of the resulting manganese(II) complex, [MnL1](ClO4)2.H2O (3) is reported here. It has been shown that the manganese atom is bonded to five nitrogens of a macrocyclic ring and two nitrogens of the pendant arms. The arrangement is slightly distorted to pentagonal bipyramidalin whereas the nitrogens of 2-pyridylmethyl groups occupy apical positions. The synthesized complexes were screened for their antibacterial activities against four bacterial strains and the complexes showed antibacterial effects.
    Journal of the Iranian Chemical Society 02/2014; 11:101–109. DOI:10.1007/s13738-013-0280-y · 1.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, there is an attempt to review the developments in the design and synthesis of pyridine containing [1+1] and [2+2] macrocyclic Schiff-base ligands, formed by condensations of 2,6-diacylpyridine or 2,6-diformylpyridine and appropriate polyamines, which utilize the templating capability of different metal ions to direct the synthetic pathway. The reduction of the cyclic Schiff-bases to their related amine derivatives is also considered since this leads to more flexible ligands capable of structural elaboration through donor groups. Attention is mainly paid to the synthetic and structural aspects of the resulting metal complexes, particularly to the role of the coordination preferences of the different metal ions in directing the synthesis totally or preferentially towards mono-, di- or poly-nuclear entities. The preparation of functionalized ligands, containing pendant arms, capable of promoting rapid complexation and decomplexation and their use in selective metal ion transportation and separation are also paid attention to. Furthermore, a summary of the new approach of these compounds such as mechanically interlocked molecules, catalytic properties and cofactors and artificial metalloenzymes is reviewed.
    Coordination Chemistry Reviews 11/2014; 280:203-253. DOI:10.1016/j.ccr.2014.06.007 · 12.24 Impact Factor
Show more