The influence of inorganic Co(II) and organic (urea) additives on the properties and crystalline perfection of TCC single crystals grown at 30 degrees C by slow evaporation solution grown technique (SEST) is investigated. The stoichiometry of the as-grown anhydrous complex crystal was confirmed by elemental (C, H, N and S; CHNS) analysis. Incorporation of Co(II) into the crystal lattice is well confirmed by EDS and chemical tests. Powder XRD profiles of Co-TCC reveal slight changes in intensity patterns of the spectra. FT-IR studies, particularly for heavily Co(II)-doped TCC, reveal small vibrational changes. Second harmonic generation (SHG) studies reveal that TCC is NLO inactive and doping does not lead to any SHG. SEM reveals changes in surface morphology as a result of doping. Urea doping results in red shift in PL spectrum and it very much suggests the complex formation. The addition of low quantity of dopants into the crystal through the aqueous growth medium improves the crystalline perfection to a great extent as evidenced from high-resolution X-ray diffraction (HRXRD) studies. However, high dopant concentration leads to the formation of structural grain boundaries leading to deterioration of crystalline perfection. It appears that some part of the doped Co(II) occupies substitutional positions because of close atomic/ionic radii with that of the host metal. The interstitial site occupancy is predominant in the case of urea dopant. (C) 2008 Elsevier B.V. All rights reserved.