2-Aminopyridiniomethylphosphonite: A hydrogen-bonded polymer from the hydrolysis of 1,3,4-diazaphospholo[1,2-a]pyridine

Condensation of 2-aminopyridine and chloromethyldichlorophosphane yields 1,3,4-diazaphospholo[1,2-a]pyridine 2 . Methanol adds to 2 while diethylamine does not; with additional elemental sulfur, in both cases the sulfides 4, 6 of the respective adducts are formed. Hydrolysis of 2 specifically opens the PN-bond and gives the zwitterionic 2-aminopyridinio-methylphosphonite 7 . The compound crystallizes with one molecule water in the monoclinic space group P 2₁/c with a = 25.490(7)Å, b = 7.365(4)Å, c = 9.088(3)Å, β = 100.06(3)°, and Z = 8 with two independent molecules of 7 and of water. In the crystal hydrogen bonds connect the molecules of 7 to form double-chain structured polymers. The individual double-chains are linked to each other by hydrogen-bonded water molecules.     

DFT and experimental studies of the structure and vibrational spectra of curcumin

The potential energy surface of curcumin [1,7‐bis(4‐hydroxy‐3‐methoxyphenyl)‐1,6‐heptadiene‐3,5‐dione] was explored with the DFT correlation functional B3LYP method using 6‐311G* basis. The single‐point calculations were performed at levels up to B3LYP/6‐311++G**//B3LYP/6‐311G*. All isomers were located and relative energies determined. According to the calculation the planar enol form is more stable than the nonplanar diketo form. The results of the optimized molecular structure are presented and compared with the experimental X‐ray diffraction. In addition, harmonic vibrational frequencies of the molecule were evaluated theoretically using B3LYP density functional methods. The computed vibrational frequencies were used to determine the types of molecular motions associated with each of the experimental bands observed. Our vibrational data show that in both the solid state and in all studied solutions curcumin exists in the enol form. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Two new ternary vanadyl(IV) complexes containing ATP

Summary Two new ternary VO²⁺ complexes, [VO H₂ATP-dipy]·6H₂O (dipy: , dipyridyl)and [VO H₂ATP-ophen] ·6H₂O (ophen:o-phenanthroline), were prepared and characterized by chemical analyses, x-ray diffractometry, u.v./vis. and i.r. spectroscopy. Both complexes are probably polymeric, with the terminal PO₃-moieties of H₂ATP acting as bridging ligands.     

Characterization of the interactions between synthetic nematic LCs and model cell membranes

Differential scanning calorimetry (DSC) was used to characterize interactions of synthetic LCs, 4‐pentyl‐4′‐cyanobiphenyl (5CB) and TL205 (a mixture of cyclohexane‐fluorinated biphenyls and fluorinated terphenyls) with simple mimics of cell membranes. The investigation was motivated by reports that living cells can be placed into contact with TL205 without apparent toxicity, whereas contact of cells with 5CB leads to cell death. The tendency was examined for 5CB and TL205 to spontaneously partition into and influence the organization for model cell membranes composed of phospholipids. Upon contact of an aqueous dispersion of DPPC liposomes with neat LC for 4 h, 5CB partitioned into the liposomes at a weight ratio of 5:1 DPPC:5CB, whereas TL205 partitioned at a ratio of 310:1 DPPC:TL205. DSC endotherms indicated that the 5CB spontaneously partitioned into the liposomes was far more perturbing than TL205. DSC endotherms of DPPC bilayers containing the same concentration of either 5CB or TL205 also revealed 5CB to be more perturbing than TL205. The effect of up to 7.8 wt % of TL205 was small, resulting in a shift in the melting transition from 41.4°C to 40.1°C and a minor change in peak width, indicating only minor effects on the organization of the bilayer. These effects are similar to those caused by cholesterol in DPPC bilayers. In contrast, 5CB shifted the DPPC melting transition from 41.4°C to ～36°C and increased the width of the transition peak by a factor of ten, indicating a destabilization of the ordered phase in the bilayer and a disruption of the cooperative nature of the gel‐to‐LC transition of the phospholipid bilayer. Taken together, the results demonstrate that 5CB and TL205 differ significantly in their interactions with model cell membranes, which suggests one possible origin of their different toxicities toward cells.     

WILLGERODT-KINDLER'S MICROWAVE-ENHANCED SYNTHESIS OF THIOAMIDE DERIVATIVES

The Willgerodt-Kindlerreaction was applied to a series of aromatic aldehydes and ketones. The reactions were performed in a dipolar aprotic solvent (mainly DMF) in the presence of a base catalyst (4-methylmorpholine) and utilized microwave (mw) irradiation. The pulsed mw technique rather than the continuous irradiation was preferred because it limited side reactions and hydrogen sulfide production. While not always superior to the thermal activation of the reaction, the procedure involving repetitive short pulses of microwave irradiation was found to be faster and result in consistently cleaner products. The technique can be easily applied in a fast parallel synthesis process.     

Poincaré series of modules over compressed Gorenstein local rings

Given two positive integers e and s we consider Gorenstein Artinian local rings R   whose maximal ideal m$\mathfrak{m}$ satisfies m^s≠0=m^s+1${\mathfrak{m}}^s\ne 0={\mathfrak{m}}^{s+1}$ and _rankR/m(m/m²)=e${\mathrm{rank}}_{R/\mathfrak{m}}(\mathfrak{m}/{\mathfrak{m}}^2)=e$. We say that R is a compressed Gorenstein local ring   when it has maximal length among such rings. It is known that generic Gorenstein Artinian algebras are compressed. If s≠3$s\ne 3$, we prove that the Poincaré series of all finitely generated modules over a compressed Gorenstein local ring are rational, sharing a common denominator. A formula for the denominator is given. When s is even this formula depends only on the integers e and s  . Note that for s=3$s=3$ examples of compressed Gorenstein local rings with transcendental Poincaré series exist, due to Bøgvad.     

Linking stakeholder visions with resource allocation scenarios and multi-criteria assessment

Stakeholders and decision makers often develop visions of the ideal-type future as a response to complex societal problems and design their actions accordingly. However, these actors sometimes have a limited understanding as to whether their visions are feasible, what action is required and what the potential consequences are. This paper presents a methodology for linking visions with quantitative resource allocation scenarios which show different options in implementing the visions. The consequences are then appraised by multi-criteria assessment in order to find optimal and acceptable ways of implementation. As a result, stakeholders and decision makers learn about their visions and may even rethink them before decision making. The methodology thus couples visionary ideas with analytical information, providing a novel approach using quantitative techniques in a soft framework. The methodology is illustrated via a real-world case study concerning the future energy system in a small Swiss community.     

Characterization of the interactions between synthetic nematic LCs and model cell membranes

Differential scanning calorimetry (DSC) was used to characterize interactions of synthetic LCs, 4-pentyl-4'-cyanobiphenyl (5CB) and TL205 (a mixture of cyclohexane-fluorinated biphenyls and fluorinated terphenyls) with simple mimics of cell membranes. The investigation was motivated by reports that living cells can be placed into contact with TL205 without apparent toxicity, whereas contact of cells with 5CB leads to cell death. The tendency was examined for 5CB and TL205 to spontaneously partition into and influence the organization for model cell membranes composed of phospholipids. Upon contact of an aqueous dispersion of DPPC liposomes with neat LC for 4 h, 5CB partitioned into the liposomes at a weight ratio of 5:1 DPPC:5CB, whereas TL205 partitioned at a ratio of 310:1 DPPC:TL205. DSC endotherms indicated that the 5CB spontaneously partitioned into the liposomes was far more perturbing than TL205. DSC endotherms of DPPC bilayers containing the same concentration of either 5CB or TL205 also revealed 5CB to be more perturbing than TL205. The effect of up to 7.8 wt % of TL205 was small, resulting in a shift in the melting transition from 41.4°C to 40.1°C and a minor change in peak width, indicating only minor effects on the organization of the bilayer. These effects are similar to those caused by cholesterol in DPPC bilayers. In contrast, 5CB shifted the DPPC melting transition from 41.4°C to ∼36°C and increased the width of the transition peak by a factor of ten, indicating a destabilization of the ordered phase in the bilayer and a disruption of the cooperative nature of the gel-to-LC transition of the phospholipid bilayer. Taken together, the results demonstrate that 5CB and TL205 differ significantly in their interactions with model cell membranes, which suggests one possible origin of their different toxicities toward cells.     

Zn2+ Complexes of 3,5‐Bis[(1,5,9‐triazacyclododecan‐3‐yloxy)methyl]phenyl Conjugates of Oligonucleotides as Artificial RNases: The Effect of Oligonucleotide Conjugation on Uridine Selectivity of the Cleaving Agent

2‐(3,5‐Bis{[1,5,9‐tris(trifluoroacetyl)‐1,5,9‐triazacyclododecan‐3‐yloxy]methyl}phenoxy)ethanol was synthesized and converted to a O‐(2‐cyanoethyl)‐N,N‐diisopropylphosphoramidite building block, 12 . 2′‐O‐Methyl oligoribonucleotides incorporating a 2‐[(2S,4S,5R)‐4‐hydroxy‐5‐(hydroxymethyl)tetrahydrofuran‐2‐yl)ethyl 4‐oxopentanoate or a 2‐{2‐[2‐({[(2R,4S,5R)‐4‐hydroxy‐5‐(hydroxymethyl)tetrahydrofuran‐2‐yl]acetyl}amino)ethoxy]ethoxy}ethyl 4‐oxopentanoate non‐nucleosidic unit close to the 3′‐terminus were assembled on a solid support, the 4‐oxopentanoyl protecting groups were removed by treatment with hydrazinium acetate on‐support, and 12 was coupled to the exposed OH function. The deprotected conjugates were purified by HPLC, and their ability to cleave a complementary RNA containing either uridine or some other nucleoside at the potential cleaving site was compared. Somewhat unexpectedly, conjugation to an oligonucleotide did not enhance the catalytic activity of the Zn²⁺? bis(azacrown) complex and virtually abolished its selectivity towards the uridine sites.