Studies on Synthesis, Characterization and Antibacterial Activity of ...

<strong>Studies</strong>...Purav Talaviya et al.the complexes formation 21 , whereas the band at 1420 cm -1 in the IR spectrum of PBDQ assigned to in-plane–OH deformation was shifted towards higher frequency in the spectra of the coordination polymer due to theformation of the M–O bond 22 . This was further confirmed by a weak band at 1090 cm -1 corresponding to C–O–M stretching, while bands around 750 and 660 cm -1 correspond to the N →M vibration 2 3.1 H NMR Analysis: The structural analysis of the ligand (PBDQ) was determined by 1 H NMR spectrum.NMR(DMSO) 6.9 – 8.2 ppm (15H) Multiplet Aromatic5.3 ppm (1H) Singlet (OH)4.0 ppm (1H) Singlet (NH)Magnetic Measurements: Magnetic moments of coordination polymers are given in Table-2. The diffuseelectronic spectrum of Cu +2 complex shows two broad bands, 15865 and 22690 cm -1 . The first band may bedue to a 2 Eg → 2 T 2 g transition, while the second band may be due to charge transfer. The first band showsstructures suggesting a distorted octahedral structure for the Cu +2 metal complex 24,25 . The Co +2 metalcomplex gives rise to two absorption bands at 20720 cm -1 , 19880 cm -1 and 11990 cm -1 which can beassigned 4 T 1 g(F)→ 4 A 2 g, 4 T 1 g(F)→ 4 T 1 g(P) and 4 T 1 g(F)→ 4 T 2 g transitions, respectively. These absorptionbands and the µ eff value indicate octahedral configuration of the Co +2 metal complex 26,27 . The spectrum ofMn +2 polymeric complex comprised three bands at 22965 cm -1 ,17655 cm -1 and 15379 cm -1 . These bandsmay be assigned to 6 A 1 g→ 6 A 1 g( 4 Eg), 6 A 1 g→ 4 T 2 g( 4 G) and 6 A 1 g→ 4 T 1 g( 4 G) transitions, respectively. The highintensity of the bands also suggests that they may have some charge transfer character. The magneticmoment is found to be lower than normal range. In the absence of low temperature measurement ofmagnetic moment, it is difficult to attach any significance to this. As the spectrum of the metal complex ofNi +2 show three distinct bands at 22988 cm -1 ,14695 cm -1 and 8100 cm -1 are assigned as 3 A 2 g→ 3 T 1 g(P),3 A 2 g→ 3 T 1 g(F) and 3 A 2 g→ 3 T 2 g transition, respectively, suggesting the octahedral environment for Ni +2 ion.The observed µ eff values in the range 1.93–5.11 B.M are consistent with the above moiety 28,29 .Thermal <strong>Studies</strong>: The TGA data for the Co-ordination polymers samples at different temperatures indicatethat the degradation of the co-ordination polymers is noticeable beyond 300 0 C. The rate of degradationbecomes a maximum at a temperature between 400 and 500 0 C. This may be due to acceleration by metaloxides, which form in situ. Each polymer lost about 60% of its weight when heated up to 690 0 C. Inspectionof the thermograms of all coordinated polymer samples revealed that all samples suffered appreciableweight loss in the range of 150 to 280 0 C. This may be due to the presence of a coordinated water molecule.Antimicrobial Activities: The antibacterial and antifungal data obtained from analysis are shown inTable-3 and Table-4, respectively. The increase in antimicrobial activity may be considered in light ofOvertone’s concept 30 and Tweedy’s chelation theory 31 . According to Overtone’s concept of cellpermeability, the lipid membrane that surrounds the cell favors the passage only of lipid-soluble materialsdue to which liposolubility is an important factor controlling the antimicrobial activity. On complexation,the polarity of the metal ion will be reduced largely due to the overlap of the ligand orbital and partialsharing of the positive charge of the metal ion with donor groups. Further, it increases the delocalization of -electrons over the whole chelate ring and enhances the lipophilicity of the coordination polymers. Thisincreased lipophilicity enhances the penetration of the coordination polymer into lipid membranes andblocks the metal binding sites in the enzymes of microorganisms. These coordination polymers also disturbthe respiration process of the cell and thus block the synthesis of proteins, which restricts further growth ofthe organisms.113 J. Chem. Bio. Phy. Sci. Sec. A, 2012-2013, Vol.3, No.1, 109-116.