New dimeric Schiff base quinoline complexes: Synthesis, spectral characterization, electrochemistry and cytotoxicity

Abstract

A novel Schiff base ligand (H-DPPMHQ) derived from 2-hydrazineylquinoline and 1,3-diphenyl-1H-pyrazole-5-carbaldehyde and its dimeric complexes with compositions [Cr(DPPMHQ)Cl] 2 ⋅2Cl and [M(DPPMHQ)Cl] 2 (where M = Cu(II), Co(II), Ni(II) and Zn(II)) have been synthesized and characterized using physicochemical methods like elemental analysis, magnetic susceptibility and molar conductivity measurements, multispectral techniques and electrochemical studies. The molar conductance data reveal that all metal chelates are non-electrolytes, except the Cr(III) complex which shows a Λ M value of 146.82 Ω −1 cm 2 mol −1 , indicating that it is a 1:2 electrolyte. Infrared spectral results show that the metal is organized through four nitrogen atoms (azomethine and deprotonated imine groups, pyrazole and quinoline rings) besides chlorine atoms. The NH proton is also displaced during complexation, as indicated by 1 H NMR spectral data. Based on the electron spin resonance and ligand field parameter data, the bonding parameters of these complexes have been calculated. Using Coats-Redfern and Horowitz-Metzger equations, thermodynamic parameters were determined. The spectral data indicate that the dimeric complexes have octahedral geometry around the central metal ions. The cytotoxic activities of all compounds were evaluated towards human breast cancer (MCF-7) and lung cancer (A549) cell lines.

Some divalent metal(II) complexes of salicylaldehyde‐derived Schiff bases: Synthesis, spectroscopic characterization, antimicrobial and in vitro anticancer studies

“…The molecular ion peak for 12 is observed at m / z 868.25. Other peaks due to (M + H + Br 79 ) and (M + H + Br 81 ) isotopes were observed at 870.30, 872.30 which confirms the stoichiometry of the complexes . Thus, the mass spectral results along with elemental analyses agreed with formation of [M(L 2 ) 2 ⋅2H 2 O] type complexes in 1:2 molar stoichiometry.…”

Synthesis, spectroscopic characterization, biological screening and in vitro cytotoxic studies of 4‐methyl‐3‐thiosemicarbazone derived Schiff bases and their Co (II), Ni (II), Cu (II) and Zn (II) complexes

“…In the electronic spectra of Cu (II) complexes, UV spectral bands were observed in vicinity of 15,275–15530 cm −1 and 24,300–24,850 cm −1 which were attributed for 2 B 1 g → 2 A 1 g (ν 1 ) 2 B 1 g → 2 E 2 g (ν 2 ) transitions, respectively and the magnetic moment values lies in the range of 1.82–1.92 BM corresponds to octahedral geometry …”

Preparation, Structural characterization and DNA binding/cleavage affinity of new bioactive nano‐sized metal (II/IV) complexes with oxazon‐Schiff's base ligand

“…Particle size for the hybrids was calculated using maximum intensity peak by the standard Scherrer equation : where D is the particle size; K is a constant (= 0.97); k is X‐ray wavelength ( λ = 1.5568 Ǻ); θ is Bragg diffraction angle and β is integral peak width which is converted into radian while calculation. On the other hands, the values obtained for all the complexes were in the range 46–73 nm which indicated that the particles were of nano‐size . On the other hand, the values of size of particles of Cu (II), Co (II) and Zn (II) complexes were observed at 63.84, 48.47 and 52.63 nm, respectively and these values calculated by using the highest intensity value.…”