New carboxysalicylaldehyde schiff base ligand and its copper(II) complexes

Metal-organic frameworks have become a subject of great interest lately because of their interesting features and applications in the field of catalysis, magnetism and biological studies [1]. Coordination polymers are most commonly the creators of such frameworks, and researchers have devoted great effort to the design of metal-generated networks with tailored properties [2,3]. Our group has recently been involved in the development of by-design structures based on 3d metal coordination complexes derived from Schiff based ligands [4]. Salen-based complexes of 3d metals, in which the Schiff base presents the carboxy substituent on the aromatic moiety, generate infinite coordination polymers in the presence of alkaline bases [5]. In this respect, we have obtained new carboxysalicylaldehyde Schiff base ligand, namely N,N'-bis(5-carboxysalicylidene-aminopropyl)piperazine (CBPP), characterized by NMR and FTIR spectroscopy and TG analysis. Copper(II) complexes of CBPP were synthesized by direct or template synthesis, isolated and characterized by FTIR; preliminary results suggest the formation of polymeric structures

New mononuclear cobalt (III) and manganese (III) complexes containing a hexadentate schiff base ligand

Manganese and cobalt complexes in high oxidation state play an important role in a diverse range of enzymatic and electron-transfer processes in biological systems1 and as antibacterial or antiviral agents2 . Here, we report the synthesis and crystal structures of two new mononuclear complexes [MnL](ClO4) (1) and [CoL](NO3)·2CH3OH (2) containing N,N’- bis[(2-hydroxybenzilideneamino)propyl]-piperazine (H2L) (Figure 1). X-ray structure determinations of 1 and 2 revealed that both compounds consist of mononuclear complex cations containing trivalent metal centers, MnIII or CoIII. The metal ions are coordinated in a distorted octahedral fashion by the N4 donor set of the ligand in basal and the two phenoxo oxygen atoms in apical positions. Spectral properties are consistent with the crystallographic results and the electrochemical properties of the complexes have been investigated by cyclic voltammetry. Furthermore, thermal studies were performed to deduce the stabilities of the ligand and complex

Synthesis and structural characterization of dimeric and polymeric cooper(II) complexes with schiff base as ligand

Polynuclear coordination compounds derived from multidentate Schiff base ligands are a source of new materials with applications in catalysis [1], optoelectronic materials [2], and environmental applications [3]. In extension of our previous studies [4]on polynuclear materials, we report the crystal structures and spectroscopic properties ofdimeric and polymeric copper(II) complexeswith hexadentate Schiff base N,N’-bis[(2- hydroxybenzilideneamino)-propyl]-piperazine (H2L) as ligand. Reaction of Cu(ClO4)2 hexahydrate with H2L in the presence of triethylamine affords a polymeric structure [Cu3L2(μ3-ClO4)0.66](ClO4)1.33·1.33CHCl3(1) in which the perchlorate anion acts as a tridentate ligand in a μ3-manner binding three Cu3L2 units. When NaN3 was added to the above mentioned reaction mixturea new dimeric assembly[Cu6(C24H30N4O2)4(N3)2][ClO4]2 (2) was obtained in which two azide groups bridge two Cu3L2 unitsin an end-to-end fashion. The same dimeric structure was obtained when the polymer 1 was treated with NaN3