Polymeric Transition Metal Complexes Research Articles

Nickel(II) Complex of N4 Schiff Base Ligand as a Building Block for a Conducting Metallopolymer with Multiple Redox States

Metal–ligand interactions in monomeric and polymeric transition metal complexes of Schiff base ligands largely define their functional properties and perspective applications. In this study, redox behavior of a nickel(II) N4-anilinosalen complex, [NiAmben] (where H2Amben = N,N′-bis(o-aminobenzylidene)ethylenediamine) was studied by cyclic voltammetry in solvents of different Lewis basicity. A poly-[NiAmben] film electrochemically synthesized from a 1,2-dichloroethane-based electrolyte was investigated by a combination of cyclic voltammetry, electrochemical quartz crystal microbalance, in situ UV-Vis spectroelectrochemistry, and in situ conductance measurements between −0.9 and 1.3 V vs. Ag/Ag+. The polymer displayed multistep redox processes involving reversible transfer of the total of ca. 1.6 electrons per repeat unit, electrical conductivity over a wide potential range, and multiple color changes in correlation with electrochemical processes. Performance advantages of poly-[NiAmben] over its nickel(II) N2O2 Schiff base analogue were identified and related to the increased number of accessible redox states in the polymer due to the higher extent of electronic communication between metal ions and ligand segments in the nickel(II) N4-anilinosalen system. The obtained results suggest that electrosynthesized poly-[NiAmben] films may be viable candidates for energy storage and saving applications.

Synthesis, characterization and antimicrobial study of polymeric transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)

Salen ligands comprising of o-phenylenediamine (salop) and p-phenylenediamine (salpp) have been synthesized. The salen ligand, salop undergo Schiff base reaction with Formaldehyde and Barbituric acid to generate novel polymeric Schiff base, SBOPA in one instance while the second salen ligand, salpp on Schiff base reaction with formaldehyde and piperazine gives another novel polymeric Schiff base, SBPBA. These polymeric Schiff base ligands, SBOPA and SBPBA generates polymeric metal complexes in high yields on reaction with transition metal acetates, M(CH3COO)2.xH2O where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). The polymeric Schiff bases, SBOPA and SBPBA and their transition metal complexes were systematically characterized, using various spectroscopic techniques. The structure, composition and geometry of SBOPA and SBPBA and their metal complexes were confirmed by spectral techniques (FT-IR, and 1H NMR), elemental analysis, and electronic spectra magnetic moment. On the basis of FT-IR, 1HNMR, electronic spectra and magnetic moment values Mn(II), Co(II) and Ni(II) ion were found to have octahedral geometry while Cu(II) and Zn(II) were found to be square-planar in nature. Thermogravimetric analysis (TGA) was used to evaluate their thermal behaviour and Cu(II)-SBOPA and Cu(II)-SBPBA were found to be thermally most stable. The polymeric Schiff base ligands, SBOPA and SBPBA and their metal complexes have also been screened for their plausible antimicrobial activity. Tetracyclin and Miconazole were used as standard drug to study the antibacterial and antifungal activity respectively. The Cu(II)-SBOPA and Cu(II)-SBPBA were found to be most potent antimicrobial agents.

Polymeric nickel complexes with salen-type ligands for modification of supercapacitor electrodes: impedance studies of charge transfer and storage properties

Polymeric transition metal complexes with salen-type Schiff base ligands are considered as promising materials for modification of electrical double layer capacitor electrodes. Electrochemical properties of these polymers that define their performance in supercapacitors should be influenced by the ligand structure but this influence has never been systematically investigated. This article describes results of a comparative study of capacitance and charge transfer rate in polymeric nickel complexes with six different salen-type ligands using electrochemical impedance spectroscopy, analyzes advantages and limitations of this method vs. cyclic voltammetry, and provides some insights into the structure and morphology of nickel-salen type polymers. Analysis of results obtained by different analytical techniques shows that introduction of methoxy-substituents into the phenyl rings of the salen ligand and different substituents to the diamine bridge of the ligand causes noticeable changes in electrochemical properties of corresponding polymeric nickel complexes. Experimentally obtained values of gravimetric and volumetric capacitance, as well as effective charge diffusion coefficient provide guidelines for selection of most suitable nickel-salen type polymers for application in energy storage devices, including supercapacitors.

Synthesis, Spectral Studies and Bio‐activity of Some Ligand Bridged Polymeric Transition Metal Complexes of Acetone p‐Amino Acetophenone Isonicotinoyl Hydrazone

Ligand bridged polymeric complexes of the type [M(apainh)(H2O)X] where, M=Mn(II), Co(II), Ni(II), Cu(II), and Zn(II); X=Cl2 or SO4; apainh=acetone p‐amino acetophenone isonicotinoyl hydrazone have been synthesized and characterized. The complexes are stable solids, insoluble in common organic solvents and are non‐electrolytes. Magnetic moments and electronic spectral studies suggest a spin‐free octahedral geometry for all Mn(II), Co(II), Ni(II), and Cu(II) complexes. IR spectra show tridentate nature of the ligand bonding through two >C˭N and a >C˭O groups. X‐ray powder diffraction parameters for some of the complexes correspond to orthorhombic and tetragonal crystal lattices. Thermal studies (TGA and DTA) of [Mn(apainh)(H2O)SO4] complex show multi‐step decomposition pattern of both an endothermic and exothermic nature. ESR data of Cu(II) chloride complex in solid state show an axial spectra, whereas, Cu(II) sulfate complex is isotropic in nature. The complexes show a significant antifungal activity against a number of pathogenic fungal species and antibacterial activity against Pseudomonas sp. and Clostridium sp. The metal complexes are more active than the ligand.

Sheet and chain polymeric transition metal complexes formed by N,N′-o-phenylenedimethylenebis(pyridin-4-one)

The preparations are reported of the ‘extended reach’ ligand N,N′-o-phenylene-dimethylenebis(pyridin-4-one) (o-XBP4) and of a range of its metal complexes with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II), two of which have been shown by X-ray studies to have polymeric structures. In the compound [Mn(o-XBP4)(H2O)2(NO3)](NO3) the o-XBP4 ligands link ‘Mn(H2O)2(NO3)’ units into chains which are then cross-linked into sheets by the bridging action of the coordinated nitrate. In [Cu(o-XBP4)(NO3)2] chains are also formed by the bridging action of the o-XBP4 ligands but here they simply pack trough-in-trough with no nitrate cross-linking. X-band EPR spectra are reported for these and the other Mn and Cu compounds as are relevant spectroscopic results for the other complexes.

From heterobimetallic transition metal complexes to linear coordination polymers based on cis‐ and trans‐L2Pt(CCPh)2

AbstractThe reaction of cis‐(2,2′‐bipyridine) Pt(CCPh)2 cis‐(4,4′‐dimethyl‐2,2′‐bipyridine) Pt‐(CCPh)2 and trans‐(Ph3P)2Pt(CCPh)2 towards different group 11 transition‐metal salts [M′X] (M′ = Cu, Ag; X = inorganic ligand) to give heterobimetallic or linear oligomeric and polymeric transition metal complexes is described. Different coordination modes for M′, PhCC, PPh3, and X were found in these species. The structural aspects as well as the preference for one coordination mode over another is discussed. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:521–533, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10097

Polymeric transition metal complexes of 1,4-bis- (4-pyridylsulfenylmethyl)benzene and of its 2-pyridyl analogue

The preparations are reported of a range of complexes of Mn II, Co II, Ni II and Cu II with 1,4-bis- (4-pyridylsulfenylmethyl)benzene (B4PSB) and of complexes of Co II, Ni II and Cu II with the 2-pyridyl analogue (B2PSB), together with relevant spectroscopic data. X-Ray crystallographic studies on Co (B2PSB) (NO 3) 2 show the presence of a chain structure in which five-coordinate cobalt centers are linked by bridging (B2PSB) ligands, with the remaining coordination sites about each metal atom being occupied by one very asymmetrically chelating nitrate group and an oxygen atom of a unidentate nitrate.

Coordination Chemical Studies of Some Polymeric Transition Metal Complexes with Neomycin and Their Biological Activity Uses. Indirect Determination of Neomycin by Atomic Absorption Spectroscopy (AAS)

Abstract A new series of polymeric[M(Neom)H2 O)x]n complexes have been prepared; where M= Co(II), Ni(II), Cu(II) or Zn(II) ions, Neom = neomycin and X = 2–4. The complexes have been characterized by elemental analysis, conductance and magetic moment measurements. IR spectra indicated that the bonding between neomycin and transition metal ions takes place through M-O bonds. Electronic and EPR spectra of the solid complexes are measured in order to gain information about their structurs and geometry. X- ray diffraction patterns indicated that the complexes are amorphous. The biological activity of the complexes formed has been tested towards eight microorganisms and compared with the activity of neomycin itself. A new method is described for the indirect estimation of neomycin by atomic absorption spectroscopy (AAS) using carbonate as an auxiliary ligand. The results obtained either for the pure form or in pharmaceutical formulations are accurate and precise.

Electrical conductivity of polymeric transition metal complexes derived from 2,5-diamino-1,4-benzenedithiol

Polymeric metal complexes were prepared from 2,5-diamino-1,4-benzenedithiol(DADT) and transition metal(II) chloride and an unusually high electrical conductivity was observed with the DADT/CoII complex.