The dinuclear Cu(II) complexes [Cu2(L1)2(mb)]⋅ClO4 (1) and [Cu2(L2)2(mb)]⋅ClO4 (2) (HL1 = 2‐[(2‐diethylaminoethylimino)methyl]phenol; HL2 = 2‐[1‐(2‐diethylaminoethylimino)propyl]phenol; mb = 4‐methylbenzoate) were synthesized and characterized using X‐ray crystal structure analysis and spectroscopic methods. Complexes 1 and 2 are dinuclear with distorted square pyramidal Cu (II) geometries, where Schiff base coordinates with tridentate (N,N,O) chelating mode and mb bridges two metal centres. Optimized structures and photophysical properties of ligands and complexes were calculated using density functional theory and time‐dependent density functional theory methods using B3LYP functional with 6‐31G (d,p) and LanL2MB basis sets. Interactions of the complexes with bovine serum albumin (BSA) and human serum albumin (HSA) were studied using UV–visible absorption and fluorescence spectroscopies and the calculated values of association constants (M−1) are 1.7 × 105 (1–BSA), 5.7 × 105 (2–BSA), 1.6 × 105 (1–HSA) and 6.9 × 105 (2–HSA). Interactions of the complexes with calf thymus DNA were also investigated and the binding affinities are 1.4 × 105 and 1.6 × 105 M−1 for 1 and 2, respectively. Both complexes catalytically oxidize 3,5‐di‐tert‐butylcatechol to 3,5‐di‐tert‐butylbenzoquinone in the presence of molecular oxygen.

Two novel tetranuclear closed-cubane like core framework complexes [Cu4(L1)4]⋅3(H2O) (1) and [Cu4(H2L2)4(H2O)4] (2) (H2L1=(E)-2-((1-hydroxybutan-2-ylimino)methyl)phenol; H4L2=2-((2-hydroxy-3-methoxybenzylidene)amino)-2-hydroxymethylpropane-1,3-diol) were synthesized and structurally characterized. Magnetic susceptibility measurements indicate an overall weak antiferromagnetic exchange coupling in 1, while ferromagnetic exchange coupling in 2. In agreement with their closed-cubane structure, the magnetic behavior of the two complexes have been studied by employing the isotropic spin Hamiltonian of type H=J1 (S1S3 + S1S4 + S2S3 + S2S4) - J2 (S1S2 + S3S4) (J1 describes the magnetic exchange coupling between the four Cu(II) pairs with short Cu⋅⋅⋅Cu distances, while J2 characterizes the magnetic exchange coupling between the remaining two intermetallic pairs with long distances). The PHI program was used to study their magnetic behavior. A good agreement between the experimental and fitted curves was found with the following parameters: g=2.14, J1=-20.3 cm−1 and J2=0 cm−1 for 1 and g=2.10, J1=101.1 cm−1 and J2=-51.5 cm−1 for 2

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Two dinuclear azido bridged Ni(II) complexes [Ni2(HL 1 )2(N3)(C8H7O3)]•(H2O) (1) and [Ni2(L 2 )2(N3)2(H2O)](2) [H2L 1 and HL 2 are Schiff bases, obtained from the condensation of 2hydroxy-3-methoxy-benzaldehyde with 2-amino-2-methyl-1-propanol and N,N-diethylethylene diammine, respectively; C8H7O3 = 3-methoxy-2-oxo-benzaldehyde] have been synthesized and their crystal structures have been determined. Complex 1, C32H39N5Ni2O10, crystallizes in a