[structure: see text] A new pyridone alkaloid, militarinone A (1), was isolated by bioassay-guided fractionation from the mycelium of the entomogenous fungus Paecilomyces militaris. Its structure was established by extensive spectroscopic analysis. The compound features an unprecedented side chain and a 1,4-substituted cyclohexyl moiety not previously encountered in microbial metabolites. Militarinone A had a pronounced neurotrophic effect in PC-12 cells at 10 microM concentrations.

Copper(I) complexes with steroidal ligands (see formula) undergo regio‐ and stereoselective γ‐hydroxylation in the 12β‐position of the steroid in the presence of molecular oxygen. After reduction a 17β,12β‐amino alcohol is obtained. Under hydrolytic conditions a 12β‐hydroxy‐17‐ketone can be isolated.

The homogeneous conversion of cellulose in the ionic liquid 1‐ethyl‐3‐methylimidazolium acetate with 2‐furoyl chloride, p‐toluenesulfonyl chloride, and triphenylmethyl chloride yields surprisingly pure cellulose acetate samples in any case. From NMR spectroscopic studies, it may be concluded that during the homogeneous functionalization reactive intermediates including furane‐2‐carboxylic acid/acetic acid anhydride and acetic acid triphenylmethyl ester are formed leading to the cellulose acetates with DS values in the range from 0.55 to 1.86.magnified image

High-molecular-weight, soluble and thermostable alkoxy-substituted arylene−ethynylene/arylene−vinylene conjugated polymers, 13 and 14, have been successfully synthesized through the Horner−Wadsworth−Emmons olefination of luminophoric dialdehydes 7 and 9 and bisphosphonate 12 in very good yields. They were characterized through 1H NMR, 13C NMR, IR, and elemental analysis. The investigation of their photophysical and electrochemical properties has been carried out. Although almost identical absorption and emission spectra were obtained in dilute chloroform solution for all polymers 13, the full width at half-maximum (fwhm) value of the emission curves depends on the length of the attached side chains. The presence of anthracenylene units in 14 leads to a red shift of its absorption and emission spectra relative to 13. Strong self-reabsorption after excitation in solution was observed for this polymer. The solid-state photophysical properties of 13 and 14 (photoconductivity, absorption and emission spectra, fluorescence quantum yield, Stokes shift, and fwhm) greatly depend on the nature (linear or branched), length, and location of the grafted alkoxy side groups. Photoconductivity is easily detected in polymers having octadecyloxy chains (13aa, 13ab, 14). Long linear (octadecyl, i.e., 13aa) or short branched (2-ethylhexyl, i.e., 13 cc) side chains at position R2 (phenylene−vinylene segment) are necessary to obtain sharp and well-resolved emission spectra accompanied by high fluorescence quantum yields. The quasi-donor (phenylene−vinylene segment)−acceptor (arylene−ethynylene segment) nature of these polymers could explain the great discrepancy between the electrochemical band gap energy, E g ec ≈ 1.60 eV, as obtained from the onset values of the redox potentials in cyclic voltammetry and in differential pulse polarography measurements, and the optical band gap energy, E g opt ≈ 2.30 eV, from the absorption spectra.

By utilizing click chemistry and methylation, the triazolium motif was employed to design tridentate "ligands" that bind by electron acception instead of electron donation. As electronically inverted ligands they are able to complex sulfate ions by hydrogen bonding and electrostatic interactions. The formation of mono- or bis-tridentate complexes could be achieved by controlling the degree of methylation with the appropriate reagents and was proven by NMR spectroscopy and computational methods.

The diastereomeric 16-bromo- and 16-azido-17-alcohols 5-8, 11, 12, 16, and 17 and 17-ketones 3, 4, 9, and 10 of the 13alpha-estra-1,3, 5(10)-triene series were synthesized as precursors for biologically active compounds and chiral ligands for metal complexation. Conformational investigations of these and some other compounds via X-ray analysis and (1)H NMR spectroscopy show the existence of compounds with the classical steroid conformation (ring C chair, restricted conformation of ring D) and such with an atypical ring C twist-boat and a flexible ring D conformation. It could be shown that 17beta-substituents or flattening of the D-ring are responsible for the twist-boat conformation, whereas compounds containing a 17alpha-substituent or 17-keto group possess the classical conformation. By varying the substituents, compounds with either of these conformations can be intentionally synthesized. MO calculations confirmed the relative stability of the twist-boat conformation.

A preparation of monocrystalline iron oxide nanoparticles with an oxidized starch coating, currently in clinical trials (NC100150 Injection; CLARISCAN™), was characterized by magnetization measurements, relaxometry, and photon correlation spectroscopy. By combining the results with a measure of iron content, one can obtain the size and magnetic attributes of the iron cores, including the relevant correlation times for outer sphere relaxation (SO and D), and information about the interaction of the organic coating with both core and solvent. The results are 6.43 nm for the iron oxide core diameter, a magnetic moment of 4.38 10 17 erg/G, and a water-penetrable coating region of oxidized oligomeric starch fragments and entrained water molecules. The latter extends the hydrodynamic diameter to 11.9 nm and lowers the average diffusivity of solvent about 64% (which increases D accordingly). The nanopar-ticles show little size-polydispersity, evidenced by the lowest value of r 2 /r 1 at 20 MHz reported to date, an asset for magnetic resonance angiography. J. Magn. Reson. Imaging 2000;11:488-494.

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