Department of Physics, Jadavpur University^* Department of Chemistry, MNR Post Graduate College, Kukatpally, Hyderabad, India^**
○Santu Chakraborty^* Soumen Ghosh^* Sarbani Pal^** Alok Kumar Mukherjee^*

The synthesis and ab-initio structure determination of 4-O-(4-methoxybenzoyl)-2-methyl-N-(2-pyridyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide have been performed to study the role of enolic hydroxyl group present in piroxicam on its anti-inflammatory effects. X-ray powder diffraction data were collected on a Bruker D8-Advance powder diffractometer equipped with monochromated CuK_α1 radiation (λ= 1.5406Å) over an angular range 4-90°(2θ) with step size 0.02° (2θ) and counting time 25 S^-1 per step. Indexing of the diffraction pattern revealed a triclinic system with cell parameters a=8.518(5), b=10.224(6), c=14.356(6)Å, α=72.8(1)°, β=70.8(1)° and γ=68.8(1)°. The structure solution was performed in direct space (parallel tempering mode) with space group P-1 using the program FOX. The final Rietveld refinement converged to R_p=0.0546, R_wp=0.0726, respectively. The molecule contains three essential planar parts with small deviations of the methoxy oxygen and pyridine nitrogen atom from the corresponding least-squares planes. Strong intermolecular N-H…O, C-H…O, and C-H…N hydrogen bonds connects the molecules into three-dimensional supramolecular network.