Platinum (II) and palladium (II) complexes: synthesis, antimicrobial and antifungal activity

The study aims to synthesize and examine the biological activity of mono- and binuclear platinum (II) and palladium (II) complexes containing terminal and bridging nitrite ligands against the test cultures of Bacillus subtilis B4647, Aspergillus brasiliensis (niger) F679, Pseudomonas aeruginosa B8243, and Escherichia coli. Through the interaction of mononuclear platinum (II) and palladium (II) complexes, dimeric complexes having nitrite ligands were synthesized. The composition and structure of these complexes were established using elemental analysis, conductometry, potentiometry, cryoscopy, infrared spectroscopy, X-ray diffraction analysis, and X-ray fluorescence analysis. A way to coordinate nitrite ligands with the central atom was established. Antimicrobial and antifungal properties were evaluated according to the capability of the synthesized complexes to inhibit the activity of bacteria and fungi via diffusion in agar and in vitro dilution. The minimum inhibitory and bactericidal concentrations of the complexes suppressing the visible growth of microorganisms and fungi, as well as exhibiting their bactericidal effect, ranged from 62.5–125 μmol/dm3. The obtained results revealed a high activity of the palladium (II) binuclear complex of the non-electrolytic type and the platinum (II) binuclear complex of the cationic type. Unlike mononuclear complexes, palladium and platinum binuclear complexes demonstrate higher antibacterial activity. Antibacterial effectiveness exhibited by the palladium complex of the non-electrolytic type against bacteria Bacillus subtilis and Escherichia coli, as well as fungi Aspergillus niger, is more pronounced. The only exception is the antimicrobial activity of the palladium complex against Pseudomonas aeruginosa, which is comparable to that of the binuclear platinum complex of the cationic type. By changing the structure of the complex, the composition and charge of the inner sphere, the number of coordination centers, as well as the nature and denticity of ligands, it is possible to achieve a higher toxic effect of the complexes against bacteria and fungi.

(μ-2,2′,2′′,2′′′-{[Pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(sulfanediyl)}tetraacetato)bis[aquanickel(II)] heptahydrate

Reaction of the ligand 2,2′,2′′,2′′′-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(sulfanediyl)}tetraacetic acid (H4L1), with NiCl2 leads to the formation of a binuclear complex, (μ-2,2′,2′′,2′′′-{[pyrazine-2,3,5,6-tetrayltetrakis(methylene)]tetrakis(sulfanediyl)}tetraacetato-κ5 O,S,N 1,S′,O′:κ5 O′′,S′′,N 4,S′′′,O′′′)bis[aquanickel(II)] heptahydrate, {[Ni2(C16H16N2O8S4)(H2O)2]·7H2O} (I). It crystallizes with two half molecules in the asymmetric unit. The complete molecules are generated by inversion symmetry, with the center of the pyrazine rings being located at crystallographic centres of inversion. The ligand coordinates two NiII ions in a bis-pentadentate manner and the sixfold coordination sphere of each nickel(II) atom (NiS2O3N) is completed by a water molecule. The complex crystallized as a hepta-hydrate. The binuclear complexes are linked by Owater—H...Ocarbonyl hydrogen bonds, forming layers parallel to the (101) plane. This layered structure is additionally stabilized by weak C—H...O hydrogen bonds. Further O—H...O hydrogen bonds involving binuclear complexes and solvent water molecules, together with weak C—H...S hydrogen bonds, link the layers to form a supramolecular framework.

Potentiometric Study of the Copper(II) Ions Complexation Process with Thiourea in Acidic Medium

Potentiometric titration method was used to study the copper(II) ions complexation process with thiourea in medium containing 1 mol/l of hydrochloric acid at a temperature of 298 K. It was found out that mononuclear (CuTMn) and binuclear (Cu2TMn) complexes were observed in the copper(II) --- thiourea system depending on the copper ions concentration. It was determined that in acid medium with copper(II) ions concentration less than 5 · 10--4 mol/l and mononuclear complexes of the composition are generated in the system, which constant is equal to lg β3 = 11.9. With an increase in the copper(II) ions concentration (CCu+2 > 5 · 10--4 mol/l), binuclear thiourea complex dominates in the system. Stability constant logarithm of the Cu2TM6 composition binuclear complex is equal to 27.5 and was calculated using the modified Leden's method. Based on the constants, complexes existence regions were determined depending on the ratio CTM/CCu+2. With the CTM/CCu+2 ≥ 5 relations, existence of a dominant complex significantly depends on the copper(II) ions concentration. It turned out that fractions of all complex particles were growing with an increase in the copper(II) ions concentration in the system. It was found that stability of thiourea complexes in the CuLi2+, AgLi+, AuLi+ rows was increasing

Synthesis of an Unprecedented H-stitched Binuclear Crystal Structure Based on Selective Fluorescence Recognition of Zn2+ in Newly Synthesized Schiff Base Ligand with DFT and Imaging Application in Living Cells

A zinc coordinated rare binuclear complex was synthesised and characterized by elemental analysis and single-crystal X-ray diffraction. Two mononuclear units formed by two Schiff base ligands 2-((2-(pyrimidin-2-yl)hydrazono)methyl)phenol (PHP) coordinated with...

New luminescent tetracoordinate boron complexes: an in-depth experimental and theoretical characterisation and their application in OLEDs

A group of new tetracoordinate mononuclear 2-(N-phenylformimino)pyrrolyl boron chelates [BX2{κ2N,N’-NC4H3-2-C(H)=N-C6H5}] (X=F 3; mesityl (2,4,6-trimethylphenyl, Mes) 4; C6F55; X2=1,1'-biphenyl-2,2'-di-yl 6) and the related binuclear complex [(C6F5)2B{κ2N,N’-NC4H3-2-C(H)=N-C6H4-N=C(H)-C4H3N-κ2N,N’}B(C6F5)2] 7 were synthesised via...

Synthesis, crystal structure and photoluminescence of a binuclear rhenium(I) carbonyl complex incorporated in a framework of a distorted salophen ligand

Re(CO)5Cl reacts with salophenH2 to yield Re(I)2(salophenH)(CO)6Cl. A crystal structure determination has shown that this binuclear complex contains two Re(CO)3 fragments which are bridged by a chloride and a heavily constrained salophenH– anion as ligands. Under ambient conditions in solution and in the solid state, the complex displays an orange emission which originates from the lowest-energy IL/MLCT triplet. In solution, this phosphorescence is completely quenched by oxygen.