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Research was conducted to tune the steric protection yielded by substituents on the triamidoamine ligands such that the actinide complexes would have symmetric structures but also be reactive enough to be utilized in the exploration of the chemistry of the elements of this form. Using the tert-butyldimethylsilyl ligand obtains this objective. A convenient approach to the system via the preparation of monomeric, tetravalent actinide chlorides, bromides, iodides and amides is described.

The characterization of a range of tetravalent (triamidoamine)uranium alkoxides and aryloxides A was performed as well as the isolation of bis(alkoxido) ate complexes and the subsequent electrochemical synthesis of U(V) alkoxides. All experiments were conducted under an inert atmosphere of argon either with standard Schlenk techniques or in an MBraun drybox. Results reveal that the one-electron oxidation of the ate complexes to the neutral pentavalent complexes has been characterized by cyclic voltammetric studies and performed on the chemical scale by reaction with (FeCp2)(PF6).

The synthesis and structure of the trilithium salt triamidoamines, [Li3(NN'3)(THF)3], were evaluated. The complex subsequently transformed into the solvent free compound, [Li3(NN'3)]. The method used for the preparation of the compound was the one-pot synthesis conducted at low temperature. The complex solution was then cooled at -30 degrees centigrade which resulted to the elimination of a single THF ligand and the formation of [{Li3(NN'3)(THF)2}2] colorless crystals. The one-pot method was considered as a convenient method in preparing the lithiated triamidoamine.

The water-compatible optically pure metallohelices made by self-assembly of simple nonpeptidic organic components around Fe(II) ions are now recognized as a distinct subclass of helicates that exhibit similar architecture to some natural cationic antimicrobial peptides. Notably, a new series of metallohelices was recently shown to exhibit biological activity, displaying high, structure-dependent activity against bacteria. It is also important that, thanks to their properties, such metallohelices can exhibit specific interactions with biomacromolecules. Here, following our prior report on the metallohelices that have high, structure-dependent activity against bacteria, we investigated the interactions of the series of iron(II) metallohelices with DNA, which is a potential pharmacological target of this class of coordination compounds. The results obtained with the aid of biophysical and molecular biology methods show that the investigated metallohelices accumulate in eukaryotic cells and that a significant fraction of the metallohelices accumulates in the cell nucleus, allowing them to interact also with nuclear DNA. Additionally, we have demonstrated that some metallohelices have a high affinity to DNA and are able to condense/aggregate DNA molecules more efficiently than conventional DNA-condensing agents, such as polyamines. Moreover, this capability of the metallohelices correlates with their efficiency to inhibit DNA-related enzymatic activities, such as those connected with DNA transcription, catalysis of DNA relaxation by DNA topoisomerase I, and cleavage by restriction enzymes.

The complexes FeL(2) [L = bidentate Schiff base ligands obtained from (R)-(+)-α-phenylethanamine and 4-substituted salicylaldehydes, substituent R = H, (t)Bu, NO(2), OMe, CN, OH] react with ditopic proligands 1,4-pyrazine (pz) or 4,4'-bipyridine (bpy), to give a family of optically pure Fe(II) polymeric chain complexes of formula {FeL(2)(μ-pz)}(∞) and {FeL(2)(μ-bpy)}(∞). Crystallographic studies show that a range of structures are formed including unidirectional and bidirectional linear polymers and canted zigzag chains. Interchain interactions via π-contacts and hydrogen bonding are also observed. SQuID magnetometry studies on all of the complexes reveal antiferromagnetic interactions, the magnitudes of which are rationalized on the basis of substituent electronic properties and bridging ligand identity. For complexes with bridging pz, the antiferromangnetic interaction is enhanced by electron-releasing substituents on the Fe units, and this is accompanied by a contraction in the intrachain distance. For complexes bridged with the longer bpy the intrachain antiferromagnetic couplings are much weaker as a result of the longer intrachain distance. The magnetic data for this series of chain complexes follow a Bonner-Fisher 1D chain model, alongside a zero field splitting (ZFS) model for Fe(II) (S = 2) as appropriate. The intrachain antiferromagnetic coupling J values, g-factors, and the axial ZFS parameter D were obtained., (© 2011 American Chemical Society)

A new family of optically pure tetrathiafulvalenium and tetraselenafulvalenium salts, D(3)[M(III)(S,S-EDDS)](2)·nH(2)O (where D = TTF, TSF; M = Co, Fe, Cr; EDDS = ethylenediaminedisuccinato), were synthesized electrochemically. These phases are semiconductors with conductivities between 6.9 × 10(-6) and 1.3 × 10(-5) S·cm(-1) (E(a)ca. 0.3 eV) for TTF and 2.8 × 10(-4) to 2.8 × 10(-5) S·cm(-1) (E(a)ca. 0.1 eV) for TSF compounds. While some crystals suffer from twinning, other well resolved structures consist of TTF/TSF stacks which, under the influence of the chiral anion, exhibit a periodic undulation described by an elliptical helix. The crystallographic data, along with computational work, indicate charge localization in the semiconducting motifs., (© 2011 American Chemical Society)