Tetranuclear and dinuclear Cu(II) complexes with risedronate as anti-Trypanosoma cruzi and anti-Leishmania mexicana agents. Synthesis, crystal structures, and biological evaluation

The development of new biometal-based complexes containing antiparasitic bioactive ligands is a central field of coordination chemistry that impacts bioinorganic, medicinal, and biological chemistry. Herein, two novel water-soluble polynuclear Cu(II)-complexes with formula [Cu4(4,4'-dmbp)4(μ3-HRis)2Cl2], 1 and [Cu2(5,5'-dmbp)2(μ2-HRis)(H2O)Cl] 2, (4,4'-dmbp = 4,4'-dimethyl-2,2'-bipyridine, 5,5'-dmbp = 5,5'-dimethyl-2,2'-bipyridine, HRis = risedronate), were synthesized by self-assembly solution reactions between the corresponding precursor complexes [Cu2(dmbp)Cl2] and the drug Na2Ris in aqueous media. Both Cu(II)-Ris complexes 1-2 were structurally described by single-crystal X-ray diffraction, characterized by spectroscopic tools (IR-ATR, HRMS, UV-Vis, EPR) and studied as antiparasitic agents against Trypanosoma cruzi causative agent of Chagas disease and Leishmania mexicana that is the etiological agent of cutaneous leishmaniasis. X-ray structural analysis reveals that 1 is an uncommon tetranuclear Cu4 complex where four crystallographically independent units [Cu(4,4'dmbp)]2+ are double-bridged coordinated by two tetra-deprotonated ligands HRis containing the protonated pyridine ring. All Cu(II) centers show a distorted square-based pyramid geometry, and they are coordinated by two bisphosphonate fragments from HRis in a coordination environment μ3 for each one. Crystal analysis of 2 displays a dinuclear Cu2 complex where one ligand HRis coordinated to two different units [Cu(4,4'dmb)]2+ in a μ2 mode, both Cu(II) present distorted square-based pyramid geometry. In general, complexes 1-2 are hydrostable in the millimolar concentration range and present low citotoxicity (<22% on the growth of cancer cell lines and healthy COS-7 cells) similar to the commercial drug, monosodium salt of risedronic acid (NaRis). Complexes 1-2 and NaRis were evaluated in vitro against T. cruzi epimastigotes and L. mexicana promastigotes. Results demonstrated that these Cu-Ris complexes improved the percentages of growth inhibition for T. cruzi. This inhibition ranged from 62-70% at concentrations of 5.0 mM after 24 h and 48 h incubation, compared to those observed for free, which has an inhibition of ∼38%. Under the same concentration at 24 h incubation, complex 1 has a significantly greater inhibition effect against L. mexicana (63%) compared to free NaRis (50%). Reduction in parasite metabolisms and morphological changes included membrane damage, vacuolization, reduction of size and loss of flagellum were also observed. Importantly cytotoxicity to VERO cells was minor with the Cu(II)-Ris complexes compared with NaRis. The molecular docking analysis showed significant affinity towards the enzyme farnesyl diphosphate synthase from T. cruzi (TcFPPS), including simulations of the complexes Cu(II) at the TcFPPS binding site.

Structure of a Luminescent MOF-2 Derivative with a Core of Zn(II)-Terephthalate-Isoquinoline and Its Application in Sensing of Xylenes

A new blue photoluminescent 2D metal–organic framework, 1, with formula {[Zn2(μ2-BDC)2(iQ)2]}∞ has been synthesized in a high yield under solvothermal conditions by reacting Zn(II) ions with 1,4-benzenedicarboxylic acid (H2BDC) and isoquinoline (iQ) in DMF. Compound 1 was thoroughly characterized by single-crystal X-ray diffraction, solid-state cross-polarization magic-angle spinning 13C NMR, X-ray powder diffraction, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and thermoanalysis. The crystal structure of 1 showed interpenetrated 2D frameworks consisting of dinuclear paddle-wheel cores Zn2; moreover, this material possessed thermostability up to 310 °C. The CPMAS 13C-NMR spectrum of 1 is consistent with the symmetry of the crystal structure. Luminescence studies showed that 1 strongly enhances its fluorescence emission in the presence of xylene isomers with a pronounced selectivity to p-xylene.

Cadmium–1,4-cyclohexanedicarboxylato coordination polymers bearing different di-alkyl-2,2′-bipyridines: syntheses, crystal structures and photoluminescence studies

Cd(ii) polymers, in acetone, can be used as luminescent materials for detection of CH₃CN.

Coordination polymers of 5-substituted isophthalic acid

The synthesis and characterisation of five coordination polymers - Ni2(mip)2(H2O)8·2H2O (1), Zn6(mip)5(OH)2(H2O)4·7.4H2O (2), Zn6(mip)5(OH)2(H2O)2·4H2O (3), Mn(HMeOip)2 (4), and Mn3(tbip)2(Htbip)2(EtOH)2 (5) - are reported. Preliminary nitric oxide release data on compounds 2 and 3 are also given.

Crystal structure of bis-(μ2-tetra-bromo-phthalato-κ(2) O (1):O (2))bis[aqua(N,N,N',N'-tetra-methyl-ethane-1,2-di-amine-κ(2) N,N')copper(II)]

In the title complex, [Cu₂(C₈Br₄O₄)₂(C₆H₁₆N₂)₂(H₂O)₂], the Cu^II cation is chelated by a tetra­methyl­ethane-1,2-di­amine ligand and coordinated by a water mol­ecule as well as bridged by two tetra­bromo­phthalate anions in a distorted O₃N₂ trigonal–bipyramidal geometry. The two symmetry-related tetra­bromo­phthalate anions bridge the two Cu^II cations, forming a centrosymmetric dinuclear complex in which the Cu⋯Cu separation is 5.054 (2) Å. Intra­molecular classic O—H⋯O hydrogen bonds and weak C—H⋯O hydrogen bonds occur in the dinuclear mol­ecule. In the crystal, the mol­ecules are linked by weak C—H⋯Br and C—H⋯O inter­actions into supra­molecular chains propagating along the b-axis direction.

Alkyl linker effects on the coordination topology of ditopic di(2-pyridylmethyl)amine carboxylate ligands with ZnIIand CuII: polymersvs.macrocycles

Di(2-pyridylmethyl)amine carboxylates with short alkyl linkers afford coordination polymers whereas the longer homologues favour macrocyclic topologies.

Coordination polymers of ZnIIand 5-methoxy isophthalate

Four different coordination polymers were prepared by reaction of Zn(OAc)₂and 5-methoxy isophthalic acid using various aqueous/aqueous alcohol solvent systems.