Investigation on the physicochemical properties of bis[4-(2-aminoethyl) morpholine-K2 N, N'] diaquanickel (II) dichloride NLO-single crystal

A novel ultramarine blue single crystal of bis[4-(2-aminoethyl) morpholine-K-2 N, N '] diaquanickel(II) dichloride (AEMNC) was synthesized using a slow-evaporation solution-growth technique. Single-crystal X-ray diffraction analysis (XRD) confirmed the monoclinic structure, with unit-cell parameters of a = 8.6495 angstrom, b = 8.6593 angstrom, c = 13.1882 angstrom, and beta = 107.415 degrees. The molecular structure consists of one Ni2+ ion coordinated with two 4-(2-aminoethyl) morpholine ligands and two water molecules. The FTIR analysis verified the presence of key functional groups, while UV-Vis studies revealed a cutoff wavelength of 249 nm and an optical band gap of 4.5 eV, highlighting its potential for optical applications. Thermal analysis indicated that AEMNC is stable up to 115 degrees C, and the Vickers hardness number of 113.3 kg/mm(2) confirmed its mechanical robustness. Dielectric studies showed a high dielectric constant at low frequencies, decreasing with frequency, indicating space-charge polarization. Most notably, Z-scan measurements demonstrated a significant third-order nonlinear optical susceptibility (chi(3)) of 6.54 x 10(-11) esu, surpassing that of well-known materials like potassium hydrogen phosphate (KDP). These findings establish AEMNC as a promising candidate for nonlinear optical applications, with superior mechanical and optical properties.