Growth and characterisation of crystals of a new organic complex of thiourea with quinine sulphate dihydrate: An NLO material

• Organic materials showing Second Harmonic Generation (SHG) effects find wide applications in optoelectronic industries.
• Single crystals of thiourea complex of quinine sulphate dihydrate (TQS) are grown by gel method.
• TQS structure is stabilized by strong intermolecular hydrogen bonds and the crystal structure has not been reported so far.
• FT-IR is used to determine the functional groups and thermal decomposition behaviour studied by TGA/DTA.
• Kurtz–Perry technique confirms the frequency doubling by the TQS crystals.

An organic complex of thiourea and quinine sulphate dihydrate (TQS) has been grown for the first time by gel method. The structure determination was done by the single crystal XRD technique. The crystal belongs to monoclinic system, P21 space group with cell dimensions a = 6.228 (3) Å, b = 20.4051 (4) Å, c = 11.0600 (6) Å, β = 101.9811(2)°. The crystal structure is stabilized by the hydrogen bonding. The functional groups present in the complex were analysed by the Fourier Transform Infrared spectroscopic method. The stoichiometry of the complex was confirmed by the elemental analysis. Thermal properties of the complex were determined by TGA and DTA methods and the complex melts at 222.53 °C. The optical transparency of the crystal was studied using UV–Visible absorption spectra. The optical band gap is found to be 2.5 eV. The SHG conversion efficiency of TQS was investigated using Kurtz and Perry method and found to be higher than that of the reference material, potassium dihydrogen phosphate (KDP).

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