Manganese(II) complexes with 5–nitro–2–hydroxy–benzaldehyde or substituted 2–hydroxy–phenones: Structure and interaction with bovine serum albumin and calf–thymus DNA

Coordination Compounds of Nickel(II) with 3,5–Dibromo–Salicylaldehyde: Structure and Interaction with Biomolecules

“…The calculated K b values indicate a strong binding affinity of the complexes to DNA and are higher than that of the known intercalator EB (K b = 1.23 × 10 5 M −1 ) [73], showing that complexes 1-3 may be tighter DNA-binders than EB. The DNA-binding constants of complexes 1-3 are in the range 2.83(±0.70) × 10 5 -4.22(±0.86) × 10 5 M −1 and are of the same magnitude with those calculated for a series of coordination compounds bearing substituted salicylaldehydes as ligands [24][25][26][27][28]57,[61][62][63][64]74].…”

“…The complexes present relatively high K SV values which reveal their potency to displace EB from the EB-DNA adduct in order to bind tightly to DNA. The K q values were calculated with Equation (S3) [76] using the value of 23 ns as the fluorescence lifetime of EB-DNA (τ 0 ) [77] and are within the range reported for other metal complexes containing X-salo as ligands [24][25][26][27][28]57,[61][62][63][64]74]. All complexes exhibited quenching constants higher than the value of 10 10 M −1 s −1 , implying the presence of a static quenching mechanism for their interaction with the EB-DNA adduct, which indicates the formation of a new adduct between DNA and the complexes under study, and confirms indirectly intercalation as the most possible mode of interaction.…”

“…In both compounds, the deprotonated 3,5-diBr-salo − ligands are coordinated to Ni(II) ions in a bidentate mode through the aldehydo and phenolato oxygen atoms. In complex 2, a NiN 2 O 4 coordination sphere is expected around Ni(II) formed by two bidentate 3,5-diBr-salo − ligands and a bidentate phen ligand leading to a structure (Figure 3) similar to that of complex 1 and other reported complexes with formula [M(X-salo) 2 (N,N ′ -donor)] [24,[26][27][28]61,62]. On the other hand, complex 3 is expected to have a NiO 6 coordination sphere originated from the coordination of two bidentate 3,5-diBr-salo − and two methanol ligands and a structure ( (5-Br-saloH = 5-bromo-salicylaldehyde) [56].…”

“…The most often case is the arrangement of the phenolato oxygen atoms in trans positions, as found in a series of Zn(II) [26,28,62], Cd(II) [63,64], and Co(II) [65][66][67][68] mononuclear complexes. Quite often found is the trans arrangement of the aldehyde oxygens, as reported in a series of Zn(II) [62], Mn(II) [24,61], Cd(II) [64], and Co(II) [68] complexes. It should also be noted that complex 1 is the first neutral Ni(II) complex bearing X-salo − and N,N ′ -donor ligands that is structurally characterized by X-ray crystallography; till now, the reported crystal structures refer to cationic Ni(II) complexes of the general formula [Ni(X-salo)(N,N ′ -donor) 2 ] + [55][56][57].…”

“…In both complexes, the Ni-O phenolato ( Such cis arrangement of the phenolato and aldehyde oxygen atoms around the metal ion is the least often found in the crystal structures of complexes bearing the formula [M(X-salo) 2 (N,N ′ -donor)] reported so far. In addition to complex 1, this arrangement has been observed in the structures of [Zn(3,5-diCl-salo) 2 (bipyam)] (3,5-diCl-saloH = 3,5dichloro-salicylaldehyde; bipyam = 2,2 ′ -bipyridylamine) [27], [Mn(5-NO 2 -salo) 2 (phen)], and [Mn(5-NO 2 -salo) 2 (bipy)] (5-NO 2 -saloH = 5-nitro-salicylaldehyde; bipy = 2,2 ′bipyridine) [61]. The most often case is the arrangement of the phenolato oxygen atoms in trans positions, as found in a series of Zn(II) [26,28,62], Cd(II) [63,64], and Co(II) [65][66][67][68] mononuclear complexes.…”