3d-metal complexes with Schiff bases containing a disiloxane unit. Synthesis, X-ray structure, spectral and cyclic voltamperometry characterization, thermogravimetric and magnetic properties In specific publications it was demonstrated that inclusion of transition metals into polymers and metallosupramolecular polymers induces specific physicochemical properties, which permits to obtain such materials as: functional soft materials, high density magnetic and spintronics devices for storage information, intrinsically magnetic and conducting polymers, hierarchical self-assembled supramolecular structures of different type – 1D, 2D, or 3D, bio-metalopolymers hybrids, metal-organic frameworks (MOFs) etc. [1]. The developments in the metallopolymers also include silicone component, in which the research expanded to organometallosiloxanes and polymeric derivatives, polyorganometalosiloxanes, containing Si-O-M bond, or metal complexed through organic groups attached to the siloxane moiety [2]. The metal can be inserted in the main chain or in side position. Moreover, the type and geometry of chemical bonds between metal ions and donor atoms of polymer ligand play very important (sometimes crucial) role in determining the properties of metallopolymers. One of the many characteristics of metal-organic-polymers is its magnetism [3]. The majority of magnetic metal-organic-polymers (MOFs) are those containing paramagnetic metal centers and in particular, 3d- and 4f- transition metals, which may exist in different oxidation states, spin states, and are characterized by magnetic anisotropy (Co and Ln). This range of variables gives large possibilities, i.e. opens a field without frontiers. In this topic, the results obtained in the Institute of Macromolecular Chemistry „P. Poni” (Romania Academy, Iasi) during last 2 years are included. Cu(II), Mn(II), Co(II), Ni(II) complexes with some novel Schiff bases derived from different organic aldehydes (2- hydroxybenzaldehyde,figureScheme 1. Metallopolymeric structures containing highly flexible siloxane sequence and Co(II) and Zn(II) metal centers have been also obtained and characterized.2,4-dihydroxybenzaldehyde, 2-hydroxy-3,5-dibromobenzaldehyde, 2-hydroxy-5- nitrobenzaldehyde, 2-hydroxy-2-chlorobenzaldehyde, 2,6-diformyl-4-methylphenol, pyrrol-2- carboxaldehyde) and 1,3-bis(3-aminopropyl)tetramethyldisiloxane prepared in situ and characterized by FTIR, UV−vis, EPR spectroscopies, X-ray diffraction methods, magnetic susceptibility measurements, cyclic voltammetry, thermogravimetrical analysis (TGA) and differential scanning calorimetry (DSC). Between Mn(II) (S=5/2) centers in dimer complexes with Schiff base ligand based on 2,6-diformyl-4-methylphenol (Scheme 1b), the antiferromagnetic interaction was demonstrated with the following exchange parameters (model HDVV): g=2.018(2); J= - 0.453(5) cm-1 for one and g=2.074(1); J= - 0.708(3) cm-1 for another complex. 3d- and 4f- metal clusters and polymers with furoic acids. Synthesis and properties [4] Interest to carboxylates of 4f- metals is determined by a number of features for this type of compounds, such as luminescent and distinguished magnetic properties. Using the reaction described in scheme 2 two sets of polymer complexes of composition {[Ln2Sr(Ba)(C5H3O3)8(H2O)3.5]}n·2H2O, where C5H3O3 = 2-Fouroic acid, Ln = La3+, Pr3+ , Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Ho3+, Er3+, Yb3+, were obtained Scheme 2. Synthesis of polynuclear complexes of lantanides. X-ray investigations of synthesized complexes permited to elucidate five types of coordination of 2-fouroic acid. Luminescence spectra of Europium and Neodimium complexes consist of all bends characteristic for 5D0 → 7Fj (Eu3+) and 4F3/2 → 4 I9/2 (Nd3+ ) transitions. The good fit of experimental and theoretical dependence of magnetic susceptibility of Eu complex on temperature was obtained for λ = 370 cm-1 which is near to λ = 363 cm-1 from luminescence data. Cluster [FeIII 7DyIII 4O4(OH)3(tea)2(Htea)3(piv)7(H2O)2](NO3)3], where H3tea= triethanolamine, Hpiv=pivalic acid, has asymmetric structure. Below 8 K, this complex shows slow relaxation of the magnetization. The form and frequency dependence in-phase (χ') and out-of-phase (χ'') signal indicates that this compound has a Single Molecula Magnet characteristics at 2.95 K. Replacement of Fe3+ with M2+ (M = Mn, Co, Ni) in the structure of a fragment {Fe2MO} leads to evident reduction of symmetry of the electronic cloud around a Fe-57 nucleus (Mossbauer measurements). This fact was explained by a lowering of the C3V symmetry of the {Fe3O} fragment to C2V symmetry of the {Fe2MO} fragment. At the same time, the nature of the metal seemed to have no effect on the electric field gradient of the metal as well as on the structure of the coordination center. The results of the biotechnological investigations have been demonstrated that some Fe(III) coordination compounds of this series can be used as regulators of the biochemical composition of cyanobacterium Spirulina platensis biomass. The supplementation of these compounds in concentrations exceeding 5-10 mg/l positively influences to the content of amino acids, peptides and carbohydrates in biomass. Ferrocene-appended porphyrins: Syntheses and properties Mezzo linked ferrocene–porphyrins are well known donor acceptor systems. They have especially emerged as efficient artificial photosynthesis models owing to their ability to produce long-lived charge separated states [5]. Using the method Lindsey the synthesis of 5,10,15,20-tetra (ferocenil) porphyrin was performed and then by introducing of copper(II) ion the final product 5,10,15,20-tetra (ferocenil) copper (II) porphyrinate was obtained. The products were confirmed by chemical analysis (Atomic absorption) and data of spectral methods NMR, IR, UV-Vis, Mossbauer. UV-Vis spectroscopy data {λmax, nm (ε * 10-4 , l/mol*cm)}: 318 (4.8), 430 (20.1), 486 (5.6), 669 (3.5) indicates the possibility of using such complexes as dye in the Graetzel cell type. 3d- metal clusters as precursors for nanomaterials Original methods to obtain nanoparticles of metal oxides (Fe2O3), (Fe2O3•MxOy) using as precursors the homo-and heteronuclear iron carboxylates were developed. Synthesized nanoparticles Fe2O3 were characterized by TEM and Mössbauer spectroscopy. The data of these two methods have permitted to elucidate the histogram of particles and number of iron states present in the sample. In dependence of the used process the average diameter of particles changed between 1-2, ~ 6 or 20 nm. Mossbauer spectra of obtained particles show a gradual evolution from a quadrupole doublet at T>60 K to some sextets at T< 60 K what is characteristic for superparamagnetic particles.