Lanthanoid compounds exhibiting intense emission are fascinating because of their wide usage in diverse fields of sci-tech. Among plausible applications of such luminescent and phosphor materials, are the light-emitted diodes (LEDs) in different kinds of electronic devices, fluorescent labels in life science, pharmaceutical science, etc. Most notably, trivalent europium has characteristic sharp absorption and emission bands in the visible range with high color purity. Unfortunately, due to Laporte f-f forbidden transitions, they not only show poor absorptivity but also evidence weak emissions. To overcome this deficiency, organic chelators are attached to the lanthanoid ions that serve as an “antennae” or “sensitizer,” that harvest and transmit the energy to the lanthanide ions. In this research, initially, a number of Ln(A-A')mx(H2O)ny (m and n = denticity of the ligand; and mx + ny = coordination of metal ion) chelates are designed by molecular simulation techniques where, A- A' are highly absorbing bidentate primary ligand (i.e., hexafluroacetylacetonate). The water molecules subsequently be replaced by a suitable secondary neutral ligand L (e.g., pyridine-N-oxide, bipyridine, pyrazole, etc.) giving rise to Ln(A- A')mxLny, thus eliminating the quenching caused by coordinated water molecules. The geometry, electronic and emission spectra, energy gap, radiative and non-radiative emission, intensity parameters, etc., are evaluated by quantum mechanical semi-empirical theory calculations.