The use of Amino acid transitionmetalcomplexes as antimicrobial agents has been reported recently. During the past decades, much importance has been given to the synthesis of new transitionmetalcomplexes and the evaluation of these agents for their antibacterial and antifungal activity. In the last few years so many studies has been done on the structure and chemical behavior of several metalcomplexes to find out an alternative against the antimicrobial drugs. This study emphasis special interest to the discovery of the new metalcomplexes possesses antibacterial and antifungal activity. A survey of literature has indicated that no work has been done on Cu (II), Ni (II), Mn (II) and Co (II) complexes of benzilic acid and amino acid hence the same was undertaken and findings are reported in the present paper. The physicochemical investigation on the bivalent metalcomplexes was carried out by conductometric, magnetic and spectral techniques with the object to compare their properties. Alanine is an alpha-amino acid encoded by the genetic code. It occurs in bacterial cell walls and in some peptide antibiotics and is an intermediate in sugar metabolism, cause higher blood pressure in human when present in large quantity. Rhizoctonia solani is a soil born plant pathogen cause plant diseases like collar rot. Phytophthora capsici is a plant pathogen that causes foot rot of peppers and Colletotrichum gloeosporioides is a fungus which attacks fruits, ornamental plants etc.
Functionalised terpyridine units are of interest for use in molecular electronics but have not been extensively studied. As a terpyridine unit has three nitrogen atoms it is able to act as a tridentate ligand, Figure 2.2. Functionalisation of the terpyridine ligand can also be easily achieved making them an ideal ligand to use in transitionmetal complex single molecule conductance measurements. There have been extensive successful studies into terpyridine as a complexing ligand for various transitionmetal ions. The common geometry of the bisterpyridine complexes is a distorted octahedral geometry, because the most common connectivity for the transitionmetal ion is hexacoordinate.
without O- bridging (complexes 1, 3 and 8) or with O- bridging (complex 2). In case of complexes 4, 6 and 7, the hydrazone behaves as dianionic NNO tridentate with or without O- bridging. However, the latter mode of bonding is not observed in our previous study for a similar isatinic hydrazone; 3-[2-(4,8-dimethylquinolin-2-yl)hydrazono] indolin-2-one . This is due to the presence of the Me- group in the 8- position in close proximity to the hetero- cyclic N- atom of the quinoline ring . Hence, the degree of basicity and deprotonation of the hydrazone as well as the mode of bonding are highly affected by the position of the Me- group. The dimeric complexes (2 and 7) have the trans arrangement and are formed via lactim bridging, whereas the binuclear complex (8) is formed via chloride bridging. Characterization of the obtained complexes was achieved via elemental analyses, magnetic and conductivity measurements as well as spectral studies.
assignable to υ C=S group appeared unchanged in the IR spectra of the complexes excluding the possiblility of coordination through sulphur atom. Thus the ligand is behaving in tetradentate manner. The ligand N,N’-dimethyl-4-amino bunzaldehyde thiocarbohydrazone has behaved in tri-dentate manner as indicated by IR spectra. The bands due υ C=N and υ C=S group have been shifted to lower positions suggesting involvement of these groups in coordination. This ligand is therfore behaving in tridentate manner.
Background: The transitionmetalcomplexes formed from Schiff base is regarded as leading molecules in medicinal chemistry. Because of the preparative availability and diversity in the structure of central group, the transition met- als are important in coordination chemistry. In the present work, we have designed and prepared Schiff base and its metalcomplexes (MC 1 –MC 4 ) and screened them for antimicrobial, anticancer and corrosion inhibitory properties. Methodology: The synthesized metalcomplexes were characterized by physicochemical and spectral investigation (UV, IR, 1 H and 13 C-NMR) and were further evaluated for their antimicrobial (tube dilution) and anticancer (SRB assay)
Thermogravimetric analyses (TGA and DrTA) of the Schiff base ligand and its chelates are used to : (i) get information about the thermal stability of these new complexes, (ii) decide whether the water molecules (if present) are inside or outside the inner coordination sphere of the central metal ion, and (iii) suggest a general scheme for thermal decomposition of these chelates. In the present investigation, heating rates were suitably controlled at 10 0 C min -1 under nitrogen atmosphere, and the weight loss was measured from the ambient temperature up to ≅ 1000 0 C. The data are provided in Table-4. The weight loss for each chelate was calculated within the corresponding temperature ranges. The TGA curve of Schiff base ligand exhibits a first estimated mass loss of 49.93% (calcd: 50.76%) at 30-400 0 C, which may be attributed to the liberation of C 8 H 6 O 2 as gases. In the 3 rd and 4 th stages within
Now a days there has been growing interest in the structural study of the complexes derived from organic compounds containing oxygen and nitrogen donors with antimicrobial activity. Quinones are the naturally occurring materials in soil plants 2 and animals 3 . It has important role in many biological electron transfer processes. In these processes they are reversibly reduced while divalent metal centers are oxidized. The derivative of quinone, lawsone (2
, 1993). However, an increase in frequency of complex 1 may be attributed to back bonding from metal to and υ(C=S) in the ligand shifted to lower frequency or found missing in the complexes suggesting the coordination of thiol or thiolate sulphur (Beraldo et al, 2001; From the Far IR region of the spectra, N), υ(M-S), υ(M-Cl) ) bands in the complexes. Analysis of IR spectral data (table 1) shows that the ligand is bidentate with azomethine nitrogen and thione/thiolate sulphur as potential donor sites forming five membered chelates with the metal
Modified antibacterial test was performed using the agar well diffusion method. The microorganisms were inoculated on Muller Hinton Agar and spread uniformly using sterile spreader in Petri plates. Three wells of 6 mm in diameter were made on Muller Hinton Agar using a sterile well puncher. The cut agar blocks were carefully removed by the use of forceps sterilized by flaming. 50 µL and 100 µL of the freshly prepared solution of metal complex (1 mg/mL) in DMSO were poured into two wells and negative control DMSO is poured in one well and the plates were allowed to stand for 1 h at room temperature for the diffusion of the substances and before the growth of organism commenced, the plates were incubated at 37 °C for 4 h. Antimicrobial activity was determined by measuring the diameter of zones showing complete inhibition.
The purity and formation were ascertained by determining the melting points of recrystallized samples on electrothermal melting temperature apparatus in open capillaries, by running single spot on TLC and carbon, hydrogen and nitrogen analyses (Reported in Table 1) carried out by micro analytical technique on Elemental Analyser Euro-E 3000. Infrared spectra were recorded in the range of 4000-400 cm -1 on ʻ Bruker spectrophometer’ by using KBr pellets. 1 H- NMR spectra of the synthesized dihydrazide was recorded in acetone solvent on NMR spectrophotometer Bruker DRX 300(MHz FT- NMR with low and high temperature facility (-90ºC to +80ºC) and electronic spectra of complexes were recorded on Lab-India UV-Visible spectrophotometer UV 3000 + in DMSO at room temperature. The magnetic susceptibilities were measured at room temperature on a Gouy balance using CuSO 4 .5H 2 O as calibrant.
FT IR spectra: The IR spectra of the complexes are compared with that of the free ligand to determine the changes that have taken place during the complexation. All data are listed in table-2. IR spectrum exhibit a strong band at 1645 cm -1 which is characteristic of the azomethine group (C=N) in the free Schiff base. In IR spectra of complexes, this band shifts to lower frequency of 1588-1560 cm -1 which indicates that the azomethine nitrogen is one of the coordinating atoms in the Schiff base 35-37 . All complexes and ligand show band in the region 1014-1069 cm -1 and 756-758 cm -1 can be assigned to phenyl ring vibration. The IR broad band of metalcomplexes in the range of 3111-3470 cm -1 indicate the presence of coordinated water molecule 38, 39 in the metalcomplexes. The spectra of the metalcomplexes also show some new bands in the region of 435-428 cm -1 and 581-598 cm -1 which are probably due to the formation of M-N and M-O bonds respectively 40, 41 . Two bands were observed at 1644-1651 cm -1 and 1301-1371 cm -1 assigned to ν assy coo - and ν sy coo - in complex 42 .
Thus, the results obtained from antimicrobial activity of the synthesized derivatives show that the complexes are more active towards various organisms than the ligand. Such a mode of higher biological activities of the complexes may be due to the effect of metal ion in the chelated form that disturbs the normal cell process. This in turn, prevents the protein synthesis thereby, inhibiting the further growth of the organisms. The exact biochemical means by which the complexes exhibit increased activity is not truly apparent, but possibly be explained on the origin of Tweedy’s chelation theory and Overtone’s concept 18,19 .
In this research article, we have synthesized a new piperidone ligand and its metalcomplexes. The formation of the compounds has been confirmed by the analytical data, IR, electronic, mass, 1 H NMR spectral studies, magnetic susceptibility, and molar conductance data. The above studies reveal that the piperidone ligand acts as neutral tridentate coordinating through nitrogen and hydroxyl oxygen atoms to the metal ions. The results displayed that Ru (M 7 (BHP)) and Co (M 3 (BHP)) complexes exhibit higher antioxidant activity and complexes
Ternary Schiff base transitionmetalcomplexes have been synthesized and characterized by physico-chemical and spectral techniques. The lower molar conductance value indicates that all the complexes are non-electrolytes. Based on FTIR spectra the coordinating mode of the ligands was confirmed. Based on the spectral studies square planer geometry has been proposed. All the metalcomplexes exhibited significant activities against the microbes under
All compounds have been characterized on the basis of spectral (IR, NMR) studies and elemental analysis. IR spectra (400-4000cm-1) were recorded using a KBr. Central drug research institute (CDRI), Lucknow and Department Of Chemistry, University of Rajasthan, Jaipur. 1H NMR spectra were recorded on Brucker spectrometer (300 MHz) at CDRI, Lucknow using CDCl 3 /DMSO as solvent.
The present communication deals with the result of the Schiff base ligand 3-amino 2 ethyl quinazoline 4(3H) Semicarbazone (AEQS) with bivalent transitionmetal ions, Cu(II), Co(II) and Ni(II). The ligand and its metalcomplexes are characterized on the basis of molar mass, elemental analyses, IR, electronic spectra, molar conductivity, magnetic moment measurement. The reaction of the ligand with Cu(II), Co(II) and Ni(II) resulted in the formation of the complexes have the general composition [M(AEQS) 2 ]X 2 where M= Cu(II), Co(II) and Ni(II). AEQS=3-amino 2 ethyl quinazoline 4(3H) semicarbazone and X = Cl - , Br - or I - . The studies proposes a distorted octahedral
The complexes are stable in air except those of Ti(III) & V (III) and are non hygroscopic. These are insoluble in water and common organic solvents, but soluble in DMF, DMSO and acetonitrile. The analytical data suggested 1:1 metal : ligand stoichiometr y for the complexes. The molar conductance values of the complexes suggested 1:3 electrolytic nature for trivalent metal ion & 1: 2 for divalent metal ion complexes.
Comparisons with Other Studies. As described previously, Geise and co- workers have recently reported a limited study of the effect of intervening mismatches on long-range guanine oxidation (10), and they concluded that any attenuation in long-range oxidation arose from a competition between trapping of a guanine radical at the mismatch site versus hole transport; at a guanine-containing mismatch, the guanine radical would be more accessible and, hence, easier to trap. The oxidant used as well as assemblies in which charge transport is measured differ from those described here, and that may lead to some differences between the two systems with respect to relative yields. Nonetheless, the proposed explanation of Geise and co-workers for attenuation of yield in the presence of intervening mismatches is clearly invalid here. It is evident from the results that mismatches that do not contain guanines, in fact, lead to the largest attenuation in the yield of long-range guanine oxidation. Guanine-containing mismatches instead cause at most only small perturbations in long-range charge transport. Therefore, competitive hole trapping at the mismatch site does not appear to be a key factor governing the efficiency of electron transport. Solvent accessibility is clearly, however, a more