Physicochemical and Biological Characterization of Transition Metal Complexes with a Nitrogen Donor Tetra-dentate Novel Macrocyclic Ligand

Abstract

A novel tetradentate nitrogen donor [N 4 ] macrocyclic ligand, i.e. 3,5,13,15,21,22-hexaaza-2,6,12,16-tetramethyl-4,14-dithia-tricyclo[15.3.1.1(7-11)]docosane-1(21), 2,5,7,9,11(22),12,15,17,19-decaene, has been synthesized. Mn(II), Co(II), Ni(II) and Cu(II) complexes with this ligand have been prepared and subjected to elemental analyses, molar conductance measurements, magnetic susceptibility measurements, mass, 1 H-n.m.r. (Ligand), i.r., electronic, and e.p.r. spectral studies. On the basis of molar conductance the complexes may be formulated as [M(L)X 2 ] and [Ni(L)]X 2 [where M = Mn(II), Co(II) and Cu(II), and X = Cl ) and NO À 3 ] due to their nonelectrolytic nature in dimethylsulphoxide (DMSO). All the complexes are of the high spin type and are six coordinated. On the basis of i.r., electronic and e.p.r. spectral studies an octahedral geometry has been assigned to Mn(II) and Co(II), square planar for Ni(II) complexes, and tetragonal for Cu(II) complexes. The antimicrobial activities of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against several species of bacteria and plant pathogenic fungi.

Template synthesis, spectroscopic studies and biological activities of macrocyclic complexes derived from thiocarbohydrazide and glyoxal

“…These results provide strong evidence for the formation of a macrocyclic frame [24]. A strong absorption band in the region , 1615-1640 cm 21 may be attributed to the CvN group [25]. The lower values of n(CvN) may be explained on the basis of a drift of the lone pair density on the azomethine nitrogen towards the metal atom [23,26].…”

“…The band present near 760 cm 21 in thiocarbohydrazide may be assigned to the free n(CvS). This band is also present in all complexes which indicates that sulphur is not coordinated to the metal atom [25,27,28].The absence of bands near 2550 cm 21 (characteristic of a thiol group) rule out the possibility of thione-thiol tautomerism [29]. The C-N stretch occurs in the range 1350-1000 cm 21 .…”

Antibacterial activity and spectral studies of trivalent chromium, manganese, iron macrocyclic complexes derived from oxalyldihydrazide and glyoxal

“…It was noted that a pair of bands corresponding to n(NH 2 ) at ,3300 cm 21 and 3310 cm 21 were present in the spectrum of oxalyldihydrazide but were absent in the infrared spectra of all the complexes. The disappearance of these bands and appearance of absorption band near ,1600-1615 cm 21 indicates the formation of macrocyclic Schiff's base [23,24] as these bands may be assigned due to n(CvN) [25,26]. The value of n(CvN) is lower than that usually found for azomethine linkage, may be explained on the basis of a drift of lone pair density of azomethine nitrogen towards the metal atom [27,28] indicating the involvement of the pi electrons throughout the macrocyclic framework [16] and confirm that coordination takes place through nitrogen of CvN groups.…”

Template synthesis of macrocyclic complexes and their spectroscopic and antibacterial studies

“…This confirms the condensation of carbonyl groups of isatin and amino groups of ethylenediamine 13,14 . This fact is also supported by the appearance of a new strong absorption band in the region ∼1590-1615 cm −1 , which may be attributed to ν(C=N) 15,16 . These results provide strong evidence for the formation of the macrocyclic frame 17 .…”