Synthesis and crystal structures of a new (2,3-(CH3)2C6H3NH3)H2XO4 (X=P, As)

The aim of encapsulation of 2,3-dimethylanilinium cation in (H2XO4)n polymeric anion chains is to build acentric frameworks that are efficient for non-linear optical (NLO) applications. The synthesis and structures of two new inorganic–organic NLO crystals with general formula (2,3-(CH3)2C6H3NH3)H2XO4 (X=P, As) are reported. The magnitude of their second harmonic generations (SHG) responses was found to be between the KDP and urea. They crystallize with monoclinic unit-cells and are isotopic. We have determined the structure of phosphoric salt. The following unit-cell parameters were found: a=8.866(3) Å, b=5.909(6) Å, c=10.644(5) Å, β=112.44(1)°, V=515.5(5) Å3 and DX=1.412 g cm−3. The space group is P21 with Z=2. The structure was refined with R=0.041 (Rw=0.057) for 1652 reflections with I≥3σ(I). It exhibits infinite (H2PO4)nn− chains. The organic groups (2,3-(CH3)2C6H3NH3)+ are anchored between adjacent polyanions through multiple hydrogen bonds. Chemical preparation, crystal structure, calorimetric and spectroscopic investigation are described.