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Zn(II), Cd(II) and Hg(II) complexes with a general composition[M(L)2(X)2], where L=4-aminopyridine (4AP) and X=NO2 − were prepared under microwave irradiation. The metal complexes were characterized by elemental analyses, molar conductance, IR, Far-IR, electronic, NMR (1 H, 13 C), XPS spectral and thermal studies. The spectroscopic studies reveal the composition, different modes of bonding, electronic transition, different chemical environment of C and H atoms and the electronic state of the metal atoms. On the basis of the characterization data, tetrahedral geometry is suggested for all the complexes. The free ligand (4-aminopyridine) and their metal complexes were screened against phytopathogenic fungi and bacteria in vitro and the activities were compared.

A study was carried out in the Island and mainland regions of Ramanathapuram District to characterize the physico-chemical characteristics of 87 groundwater samples in Island and 112 groundwater samples in mainland which include pH, EC, TDS, salinity, total alkalinity, calcium hardness, magnesium hardness, total hardness, chloride and fluoride. Heavy inorganic load in majority of the groundwater samples has been estimated due to the salinity, TDS, TH and chloride beyond the threshold level which substantiates the percolation of sea water into the freshwater confined zones. Although the groundwater sources are available in plenty, the scarcity of potable water is most prevalent in this coastal area. The Water Quality Index (WQI) and Langeleir Saturation Index (LSI) have also been calculated to know the potable and corrosive/incrusting nature of the water samples. The statistical tools such as principal component analysis, box plots and correlation matrix have also been used to explain the influence of different physico-chemical parameters with respect to one another among the groundwater samples. The percentage of groundwater samples in mainland was more than that in Island with respect to the acceptable limit of WHO drinking standard, especially in TDS, CH, TH and chloride but the converse is observed in the case of fluoride. About 8% of the mainland aquifers and 42% of Island aquifers were identified to have fluoride greater than 1.5 mg/l. The signature of salt-water intrusion is observed from the ratio of Cl/CO(3)(2-) + HCO(3) and TA/TH. A proper management plan to cater potable water to the immediate needs of the people is to be envisaged.

The Study area is the sacred Ramanathasamy temple and selected for the characterization of physico-chemical parameters viz., pH, EC, TDS, Salinity, TA, TH, Ca( + 2), Mg( + 2), Chloride and Fluoride for 22 groundwater samples and the impact of pre- and post-monsoon on the groundwater quality was also studied. The study area is well known for the chronic fresh water shortage and the locals depend mostly on springs for their fresh water needs. The Water Quality Index (WQI) computed shows the transfer of samples under unacceptable quality to acceptable quality. The Langelier Saturation Index (LSI) reflected that majority of the samples have the tendency to form scale. The Karl Pearson correlation matrix has approved the maximum relationship of calcium and chloride with respect to the total dissolved solids (TDS). It is interesting to conclude that the groundwater in the study area has very hard nature, especially of non-carbonate type.

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