Molecular structures and electronic functional properties of organic crystals p-methylphenyl-thiourea and p-chlorophenyl-thiourea

Two compounds p-methylphenyl-thiourea (I) and p-chlorophenyl-thiourea (II) were synthesized and their colorless transparent crystals were prepared by “both bath method” with two solvents acetone and ethyl acetate respectively in our EPRL. The crystal and molecular structures of (I) and (II) were determined by X-ray diffraction methods. The crystal (I) is monoclinic, space group P2 ₁/a, a=0.5639 (1), b=0.8513 (6), c=1.7898 (4) nm. The crystal (II) is monoclinic space group P2₁/a, a=1.0671 (1), b=0.8912 (1), c=0.9128 (1) nm. Dielectric constant ε_τ and dielectric loss tgδ and frequency temperature character of crystal (I) and (II) were determined, piezoelectric constant d₃₃ was determined after polarization. ε_τ of (I) and (II) are 56.3 to 138.7 and 36.3 to 123.9, d₃₃ of (I) and (II) are 58 to 314 and 37 to 245 Pc/N respectively