Crystal growth, characterization and photoluminescence studies of a new coordination compound of Ni(II) with nicotinamide and 1,5-naphthalenedisulfonic acid

A new coordination compound of Ni(II) with nicotinamide (Nic) and 1,5-naphthalenedisulfonic acid (H₂NDS) of formula {[Ni(Nic)₂(H₂O)₄]NDS}.3H₂O (NNDSN) has been prepared by gel diffusion technique. SXRD data show that the compound crystallizes in triclinic space group P \(\overline{1 }\). In the crystal structure, the Ni(II) ion is coordinated with two nicotinamide units through the nitrogen atom of pyridine ring and four water molecules. The distorted octahedral geometry of the six coordinate Ni(II) compound can be understood from the \(\angle\) N–Ni–O (ranges from 86.59(7) to 93.41(7)°), \(\angle\) O–Ni–O (88.63(7)° and 91.37(7)°) and difference in bond distances of Ni–O (2.0505(15) and 2.0533(16) Å) and Ni–N (2.1323(17) Å). 1,5-Naphthalenedisulfonate ions present in the crystal lattice balance the charge of Ni(II) ions. In the crystal structure, both coordinated and lattice water molecules, sulfonate groups of 1,5-naphthalenedisulfonate ions and NH₂ group of nicotinamide molecules are involved in intermolecular hydrogen bonding. These interactions further stabilize the crystal structure. FT-IR spectral studies show that SO₃⁻ group of 1,5-naphthalenedisulfonate ion, C = O and NH₂ groups of nicotinamide molecule are not involved in coordinate bond formation. In the UV–vis spectrum, the peaks corresponding to ³A_2g → ³T_1g (P) and ³A_2g → ³T_1g (F) transitions are observed at λ_max of 388 and 685 nm respectively. TG/DTG studies show that the crystal structure is stable up to 102 °C and the decomposition to NiO takes place through six stages. Photoluminescence studies show that the emission intensity of NNDSN can be quenched by Fe³⁺ ions. This method can be used for the sensing of Fe³⁺ ion at micro level concentration.