Designing a heterotrinuclear Cu^II—Ni^II—Cu^IIcomplex from a mononuclear Cu^IISchiff base precursor with dicyanamide as a coligand: synthesis, crystal structure, thermal and photoluminescence properties

Abstract

Schiff bases are considered `versatile ligands' in coordination chemistry. The design of polynuclear complexes has become of interest due to their facile preparations and varied synthetic, structural and magnetic properties. The reaction of the `ligand complex' [CuL] {H2L is 2,2'-[propane-1,3-diylbis(nitrilomethanylylidene)]diphenol} with Ni(OAc)2·4H2O (OAc is acetate) in the presence of dicyanamide (dca) leads to the formation of bis(dicyanamido-1κN(1))bis(dimethyl sulfoxide)-2κO,3κO-bis{μ-2,2'-[propane-1,3-diylbis(nitrilomethanylylidene)]diphenolato}-1:2κ(6)O,O':O,N,N',O';1:3κ(6)O,O':O,N,N',O'-dicopper(II)nickel(II), [Cu2Ni(C17H16N2O2)2(C2N3)2(C2H6OS)2]. The complex shows strong absorption bands in the frequency region 2155-2269 cm(-1), which clearly proves the presence of terminal bonding dca groups. A single-crystal X-ray study revealed that two [CuL] units coordinate to an Ni(II) atom through the phenolate O atoms, with double phenolate bridges between Cu(II) and Ni(II) atoms. Two terminal dca groups complete the distorted octahedral geometry around the central Ni(II) atom. According to differential thermal analysis-thermogravimetric analysis (DTA-TGA), the title complex is stable up to 423 K and thermal decomposition starts with the release of two coordinated dimethyl sulfoxide molecules. Free H2L exhibits photoluminescence properties originating from intraligand (π-π*) transitions and fluorescence quenching is observed on complexation of H2L with Cu(II).

Dinuclear Zn(II) and tetranuclear Co(II) complexes of a tetradentate N2O2 Schiff base ligand: Synthesis, crystal structure, characterization, DFT studies, cytotoxicity evaluation, and catalytic activity toward benzyl alcohol oxidation

“…Many dinuclear complexes of tetradentate N 2 O 2 Schiff base ligands with various metal ions have been reported . The corresponding dinuclear Zn(II) complexes have a flexible coordination environment with a variety of geometries such as tetrahedral, square planar, trigonal bipyramidal, square pyramidal, and octahedral …”

Antimicrobial Evaluation of Novel Metals Complexes of n- Isonicotinamido-2-hydroxy-5-methoxybenzalaldimine

“…To ascertain novel compounds with an improved pharmacological profile, researchers oriented their work towards the complexation of Schiff bases as some of them showed increased activity upon coordination/chelation with some metal ions. Some of these complexes have broad application spectrum in inorganic, organic, pharmaceutical, industrial and analytical use, in addition to their important roles in orgometallic synthesis and catalysis [20][21][22][23][24].…”

Structural and spectroscopic characterization of a new luminescent NiII complex: bis{2,4-dichloro-6-[(2-hydroxypropyl)iminomethyl]phenolato-κ3 O,N,O′}nickel(II)

“…The main reason for this is that the PET process was prevented by the complexation of the ligand to the metal ion. Therefore, the luminescence intensity may be greatly increased by the coordination of the Ni II atom (Hopa & Cokay, 2016). In addition, chelation of H 2 L to the Ni II atom increases the rigidity of the HL À ligand and thus reduces energy loss through thermal vibration decay (Das et al, 2006).…”