Johan Springborg

Ivermectin excreted in cattle dung after subcutaneous injection or pour-on treatment: concentrations and impact on dung fauna

Heifers were treated with the recommended doses of ivermectin: 0.2 mg/ kg bw by subcutaneous injection or 0.5 mg/kg bw by pour-on. An analytic procedure is described and used for the detection of ivermectin residues excreted in dung. A large amount of the higher pour-on dose was excreted during the first five days after dosing due to a more rapid distribution to intestinal contents. Later faecal concentrations after the pour-on treatment were lower than those found after subcutaneous injection. No degradation of ivermectin was detected in pats exposed in the field for up to 45 days. Ivermectin excreted in dung voided 1–2 days after both treatments significantly reduced the number of dung inhabiting larvae of Aphodius spp. (Coleoptera: Scarabaeidae), but no effect was seen in dung deposited 13–14 days after treatments. Development of cyclorrhaphan larvae was inhibited in dung deposited up to 28–29 days after subcutaneous injection treatment, but only inhibited in dung deposited up to 13–14 days after pour-on treatment. The numbers of Nematocera larvae were not affected. In a laboratory bioassay the Diptera Musca autumnalis DeGeer and Haematobia irritans (Linnaeus) suffered higher mortality in dung from heifers treated by the subcutaneous injection 13–14 days earlier than in dung from heifers treated by pour-on at the same time. After subcutaneous injection, a significant reduction in the rate of decomposition was found in dung from heifers treated 1–2 days earlier, whereas pour-on led to a delayed decomposition in dung collected up to 13–14 days after treatment.

Adamanzanes—bi- and tricyclic tetraamines and their coordination compounds

Structural modification of the important tetraaza macrocyclic ligands such as cyclen and cyclam involving ethylene and trimethylene bridging of the non-adjacent nitrogens represents a new class of macrobicyclic ligands, so-called bowl-adamanzanes. The molecular topology and size confer special properties to these amines and the most prominent features of their metal ion coordination complexes are extreme inertness and stabilization of low oxidation states. Strapping of the two secondary amine groups in the bicyclic bowl-adamanzanes leads to tricyclic tetraamine cages. These so-called cage-adamanzanes present themselves as interesting molecules with extreme acid–base properties important to model systems within biochemistry and applications such as suitable counter-ions for stablizing alkalides.

SULFUR-BONDED AND CARBON-BONDED FORMS OF THE COBALT(III) COMPLEX WITH THE LIGANDS 2-AMINOETHYL 3-AMINOPROPYL SULFIDE AND 1,1,1-TRIS(AMINOMETHYL)ETHANE

The new sulfur-bonded compound [Co(tame)( aeaps )] Cl3.H2O has been synthesized by the reaction of aeaps with Co(tame)Cl3 [tame = 1,1,1-tris( aminomethyl )ethane, and aeaps = 2- aminoethyl 3-aminopropyl sulfide or 3-thiahexane-1,6-diamine]. The Co(tame)( aeaps )3+ ion equilibrates in basic solution with the corresponding carbon-bonded species: Co(tame)( aeaps )3++HO-↔ Co(tame)(C-aeaps )2++H2O A salt of the carbon-bonded species, [Co(tame)(C- aeaps )](S2O6), has been isolated and its structure solved by X-ray diffraction analysis ( C- aeaps = 1,6-diamino-3-thiahexan-4-ide). The crystals are orthorhombic, Pna21, with cell dimensions a 20.455(10), b 9.960(10), c 8.982(10) Ǻ at 122(2) K. Preliminary thermodynamic and kinetic data are similar to the recently reported values for the corresponding coordination ion Co( tacn )( aeaps )3+ ( tacn = 1,4,7-triazacyclononane). In basic solution the Co(tame)( aeaps )3+ species exchanges one of its methylene protons orders of magnitude faster than any other methylene protons and also much faster than it forms the alkyl complex as shown by 13C n.m.r. measurements.

On the electronic structure and spectroscopic properties of a pseudo-tetrahedral cationic cobalt(II) tetraamine complex –([35]adamanzane)cobalt(II)

The electronic structure and spectrum of the unusual pseudo-tetrahedral cobalt(II) coordination compound formed with the bicyclic tetraamine ligand 1,5,9,13-tetraazabicyclo[7.7.3]nonadecane ([35]adz) has been investigated. The ligand-field absorption spectrum of the quartet ground state of the [Co([35]adz)]2+ cation was resolved into five components, which were assigned by application of angular overlap model (AOM) calculations. Furthermore, density functional theory (DFT) and time-dependent DFT (TD-DFT) were applied to investigate the structure and absorption spectrum of the cation using the B3LYP functional in combination with various basis sets. The DFT calculations provided a geometry for the cation in excellent agreement with the crystal structure of [Co([35]adz)]ZnCl4. The theoretical investigation of the electronic spectrum of the cation shows that TD-DFT can successfully be applied to open shell transition metal compounds, although only spin-allowed, single electron transitions are accounted for.