X-ray crystallography, electrochemistry, spectral and thermal analysis of some tetradentate schiff base complexes and formation constant measurements

<p>A series of new transition metal Schiff base complexes was synthesized via the reaction of H₂L (N,N′-bis(naphthylidene)-2-aminobenzylamine) with the transition metals (Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺ and Mn²⁺) and characterized by elemental analysis, ¹HNMR, FT-IR, UV-Vis spectroscopy, thermogravimetric analysis(TG) and in selected cases by X-ray crystallography. Thermodynamics of complex formation, electrochemistry of the metal Schiff base complexes and kinetic aspects of thermal decomposition of the complexes were also studied. The obtained formation constants change according to the following trend due to the electronegativity and Jahn-Teller effects of the central transition metals: Cu > Co > Ni > Zn >Mn. Cyclic voltammogram of the complexes in acetonitrile was done to evaluate the redox behavior of the complexes. Electrochemistry of these complexes showed a redox reaction without any successive reactions. Furthermore, kinetic parameters which calculated by Coats–Redfern equation revealed a first-order kinetics of thermal decomposition in all stages.</p

Complexation of 1,3-Dimorpholinopropane with Hg(II) and Zn(II) Salts: Syntheses, Crystal Structures and Antibacterial Studies

WOS: 000359393900002Two Hg(II) (1) and Zn(II) (2) complexes with general formulation M(DMP)Cl-2 where DMP=1,3-dimorpholinopropane were synthesized and structurally characterized by physicochemical methods and single crystal X-ray diffraction. An X-ray structural analysis shows that in both complexes Hg and Zn are coordinated by two nitrogen and two chlorine atoms in a form of distorted tetrahedron. The ligand and related complexes have antibacterial activity against three Gram-positive bacteria (S. epidermidis ATCC 25923, E. faecalis ATCC 23212 and S. epidermidis ATCC 34384), and also against the three Gram-negative bacteria (E. coli ATCC 25922, P. aeruginosa ATCC 27853 and K. pneumonia ATCC 70063). The results revealed that in some cases the antibacterial activity of Hg(II) complex exceeded the one of sulfisoxazole used as a standard. CCDC: 957542, 1; 957846, 2.Czech Science FoundationGrant Agency of the Czech Republic [14-03276S]Crystallography part was supported by the project (No.14-03276S) of the Czech Science Foundation

Synthesis, characterization and crystal structures of new Zinc(II) and Nickel(II) complexes containing morpholine moiety and their antibacterial studies

WOS: 000347416400013The ligand 1,2-dimorpholinoethane (DME) was used to prepare Zn(II) and Ni(II) complexes of the general formulation MLX2 (L = DME, X = Cl or NO3). Zinc(II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel(II) complex of DME when NO3 was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard.Ilam University, Ilam, IranFinancial support for this work by the Ilam University, Ilam, Iran is gratefully acknowledged. Crystallography part was supported by the project Praemium Academiae of the Academy of Sciences of the Czech Republic

<i>S</i>-Alkylation of Thiacalixarenes: How the Regio- and Stereoselectivities Depend on the Starting Conformation

<i>S</i>-alkylation of all four thiacalix[4]­arene conformations was accomplished using alkyl triflates. The corresponding sulfonium salts are formed in a highly regio- and stereoselective manner depending on the conformation used. Interestingly, only mono- or disubstituted sulfonium salts can be prepared. Although many regio- and stereoisomers are theoretically possible, only one dialkylated <i>cone</i> and <i>1,2-alternate</i> derivatives were formed, while only a single isomer of monoalkylated <i>partial cone</i> and <i>1,3-alternate</i> were isolated. The combination of experimental results with the quantum-chemical approach using the B3LYP/6-311G­(d,p) method resulted in the elucidation of the rules governing the regio- and stereochemical outcomes of the alkylation reactions. All <i>S</i>-alkylated compounds represent a novel type of substitution pattern in calixarene chemistry showing the wide-ranging possibility of thiacalixarene skeleton modifications

<i>S</i>-Alkylation of Thiacalixarenes: How the Regio- and Stereoselectivities Depend on the Starting Conformation

<i>S</i>-alkylation of all four thiacalix[4]­arene conformations was accomplished using alkyl triflates. The corresponding sulfonium salts are formed in a highly regio- and stereoselective manner depending on the conformation used. Interestingly, only mono- or disubstituted sulfonium salts can be prepared. Although many regio- and stereoisomers are theoretically possible, only one dialkylated <i>cone</i> and <i>1,2-alternate</i> derivatives were formed, while only a single isomer of monoalkylated <i>partial cone</i> and <i>1,3-alternate</i> were isolated. The combination of experimental results with the quantum-chemical approach using the B3LYP/6-311G­(d,p) method resulted in the elucidation of the rules governing the regio- and stereochemical outcomes of the alkylation reactions. All <i>S</i>-alkylated compounds represent a novel type of substitution pattern in calixarene chemistry showing the wide-ranging possibility of thiacalixarene skeleton modifications

Deferasirox pyridine solvate and its Cu(II) complex: Synthesis, crystal structure, Hirshfeld surface analysis, antimicrobial assays and antioxidant activity

Deferasirox pyridine solvate [(DFX)(py)] and its Cu(II) complex [Cu(DFX)(py)], (DFX= deferasirox, py=pyridine) were synthesized and characterized using several techniques such as elemental analysis, Fourier-transform infrared (FTIR), molar conductivity and vibrating sample magnetometer (VSM). In addition, the structure of both compounds was determined using single-crystal X-ray diffraction method. In the case of the Cu(II) complex, it was found that the Cu(II) central ion was surrounded by the ONO donor atoms of deferasirox and the nitrogen atom of pyridine. Antimicrobial activities of the synthesized compounds were investigated against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa bacteria. Likewise, the antibiofilm activity of these compounds was investigated against S. aureus and P. aeruginosa bacteria. It was observed that the [Cu(DFX)(py)] complex presented higher antimicrobial and antibiofilm activities compared with the other compounds. Furthermore, the antioxidant activity of the compounds was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging method. The [Cu(DFX)(py)] complex demonstrated a strong antioxidant activity with the IC50 of 1.1 mM.Czech Science Foundation | Ref. 18-10504

Cyanuric chloride reagent as a chloride ion donor: synthesis, crystal structure, and magnetic properties of [Cu₂(2-APM)₂(μ-Cl)₂(μ-OCH₃)₂]_<i>n</i> coordination polymer

<div><p>A new chloro- and methoxo-bridged Cu(II) coordination polymer, [Cu₂(2-APM)₂(μ-Cl)₂(μ-OCH₃)₂]_<i>n</i>·CH₃OH (<b>1</b>), was prepared using <i>in situ</i> formed chloride by the decomposition of cyanuric chloride and 2-aminopyrimidine (2-APM) as a ligand in methanol. Its solid-state structure has been characterized by elemental analysis and single crystal X-ray diffraction. X-ray crystallographic studies reveal that this compound has an extended 2-D supramolecular architecture directed by strong hydrogen bonds and aromatic <i>π</i>–<i>π</i> stacking interactions. Compound <b>1</b> shows an antiferromagnetic coupling exchange with coupling constants of −58.2 and −41.4 cm⁻¹ between adjacent copper(II) ions, in agreement with the intermetallic distances of 3.0405(5) and 3.6073(5) Å found in the crystal structure.</p></div