A Family of [Zn₆] Complexes from the Carboxylate-Bridge-Supported Assembly of [Zn₂] Building Units: Synthetic, Structural, Spectroscopic, and Systematic Biological Studies

Abstract

The three discrete [Zn 6 ] c omplexes [Na 3 Zn 6 (cpdp) 3 (μ-Bz) 3 (CH 3 OH) 6 ][ZnCl 4 ][ZnCl 3 (H 2 O)]• 3CH 3 OH•1.5H 2 O (1), [Na 3 Zn 6 (cpdp) 3 (μ-p-OBz) 3 (CH 3 OH) 6 ]• 2H 2 O (2), and [Na 3 Zn 6, have been successfully synthesized and fully characterized (Bz = benzoate; p-OBz = dianion of phydroxybenzoic acid; p-NO 2 Bz = p-nitrobenzoate). The complexes have been characterized by elemental analysis, FTIR, UV−vis, NMR spectroscopy, PXRD, and thermal analysis, including singlecrystal X-ray crystallography of 1 and 2. The molecular architectures of 1−3 are built from the self-assembly of their corresponding [Zn 2 ] units, which are interconnected to the central [Na 3 (CH 3 OH) 6 ] 3+ core by six endogenous benzoate groups, with each linking one Zn(II) and one Na(I) ion in a μ 2 :η 1 :η 1 -syn-anti bidentate fashion. The composition of the (cpdp 3− ) 3 /(Zn 2+ ) 6 complexes in 1−3 has been observed to be 1:2, on the basis of the UV−vis titration and NMR spectroscopic results, which is further supported by Xray crystallography. Systematic biological studies performed with a mice model suggested possible antidiabetic efficacy as well as anticancer activities of the complexes. When complexes 1−3 were administered intraperitoneally in mice, 1 showed a lowering in the blood glucose level, overall maintenance of the pancreatic tissue mass, restriction of DNA damage in pancreatic cells, and retention of lipid droplet (LD) frequency, whereas 2 and 3 showed hepatic tissue mass consistency by inhibiting the DNA damage in hepatic cells, prior to the exposure to a potent diabetic inducer, alloxan (ALX). Similar trends of results were observed in inhibiting the generation of reactive oxygen species (ROS) in the pancreatic and hepatic cells, as examined by spectrofluorometric methods. Thus, 1 seems to be a better compound for overall diabetic management and control, whereas 2 and 3 seem to be promising compounds for designing chemopreventive drugs against hepatic carcinoma.

Structures and Properties of a Series of High-Spin [CoII2] Complexes Supported by Ancillary Benzoate, Ortho-Hydroxybenzoate, and Para-Hydroxybenzoate Ligands

“…This versatility of the carboxylate group as a ligand has oriented its use to build an extended family of coordination complexes showing potential applications as magnetic materials . Again, continuing our research on biological activities of metal complexes of carboxylate-based ligands, we have also reported anticancer, antidiabetic, antibiofilm, and glycosidase/phosphatase activities of iron­(III), nickel­(II), copper­(II), and zinc­(II) complexes. ,− The multidentate ligand, N , N ′-bis­[2-carboxybenzomethyl]- N , N ′-bis­[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H 3 cpdp) incorporating two benzoate and two pyridine functionalities, has been well-established in studying coordination complexes with diverse applications in biological activities and magnetic properties. − ,− Therefore, motivated by our ongoing research interests in designing of smart scaffolds for exploration of magnetic and biological features in a synchronized manner, we extended our attention to synthesize a new family of high-spin cobalt­(II) complexes. In the present contribution, we report the syntheses, X-ray crystal structures, variable temperature magnetic properties, and in vitro antibacterial activities of a series of high-spin dinuclear cobalt­(II) complexes [Co 2 (cpdp)­(μ-O 2 CC 6 H 5 )] ( 1 ), [Co 2 (cpdp)­(μ- o -O 2 CC 6 H 4 (OH))]·H 2 O ( 2 ), and [Co 2 ­(cpdp)­(μ- p -O 2 ­CC 6 ­H 4 ­(OH))]·5H 2 O ( 3 ).…”

“…Among them, the coordination modes C, D, E, and F are very attractive resulting in the formation of Cu(II)-and Zn(II)-based tri-, tetra, hexa-, octa-, and decanuclear complexes with fascinating architectures. 57,62,64,65 In view of that, dinuclear Co(II) complexes 1−3 were synthesized following the routes outlined in Scheme 1. Indeed, complexes 1−3 were obtained directly by one-pot synthesis, starting from H − has very poor coordinating ability with metal ions, and hence, it can assemble mostly outside the coordination sphere.…”

Design, Synthesis and Evaluation of a Series of Zinc(II) Complexes of Anthracene-Affixed Multifunctional Organic Assembly as Potential Antibacterial and Antibiofilm Agents against Methicillin-Resistant Staphylococcus aureus

“…The current exploration originates from our continuing research interest that has drawn attention to the systematic investigation of 3d-transition metal-based complexes of carboxylate containing multifunctional organic assembly. , The occurrence of multicarboxylate groups with flexible structural backbone within the organic assembly offers extra opportunities toward formation of interesting well-designed metal complexes. In the efforts of our continuing research, we have successfully incorporated anthracene platforms as signaling components in two side arms of the organic assembly, leading to the formation of H 3 acdp that supports in achieving the desired degree of flexibility of two metal binding sites .…”

Ancillary-Ligand-Assisted Variation in Nuclearities Leading to the Formation of Di-, Tri-, and Tetranuclear Copper(II) Complexes with Multifaceted Carboxylate Coordination Chemistry

“…Carboxylate-containing ligands have been investigated for some time as a way to assemble different 3d metal ions into aggregates with relevance in the area of coordination chemistry, because their flexibility and conformational freedom support the formation of diverse multinuclear complex architectures with novel topologies. − In principle, molecular-level control over the formation of three-dimensional structures should provide a rational design and synthesis of a wide variety of these multinuclear complexes with modified properties. Carboxylate-based copper­(II) complexes may be mono-, di-, or multinuclear because of their wide-ranging coordination modes.…”

“…The focus here is on the symmetrical dinucleating ligand N , N ′-bis­[2-carboxybenzomethyl]- N , N ′-bis­[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H 3 cpdp), incorporating two pyridine and two benzoate functionalities (Scheme ). Recently, we have shown that the ligand H 3 cpdp coordinates with Co­(II), Fe­(III), Cu­(II), and Zn­(II), including Li/Na, forming a variety of higher-nuclearity complexes with smart molecular structures and interesting material/biological properties. ,,,− In those complexes, the ligand H 3 cpdp has either a trianionic (cpdp 3– ) or a dianionic (Hcpdp 2– ) form (Scheme ), exhibiting flexible coordination modes of the carboxylate groups. While further exploring the reactions of H 3 cpdp with copper­(II) ions in the presence of different exogenous ancillary ligands such as isophthalate, chloride, and phthalate/chloride/piconol, we isolated new di-, tri-, and tetranuclear copper­(II) complexes of the formulas [Cu 2 (cpdp)­(μ-Hisophth)] 4 ·2H 2 isophth·21H 2 O ( 1 ), [Cu 3 (Hcpdp)­(Cl) 4 ] ( 2 ), and [Cu 4 (cpdp)­(μ-Hphth)­(μ 4 -phth)­(piconol)­(Cl) 2 ]·3H 2 O ( 3 ).…”