Novel fluorescent isoquinoline pigments, panaefluorolines A-C from the cultured mycobiont of a lichen, Amygdalaria panaeola

Novel fluorescent substances, named panaefluorolines A-C (1-3), were isolated from the cultured mycobiont of a lichen, Amygdalaria panaeola. These structures were elucidated on the basis of spectroscopic data, especially 2D NMR.     

Amide conformational switching induced by protonation of aromatic substituent

[reaction: see text] Introduction of an electron-withdrawing group on the aromatic ring of N-methylacetanilide decreased the ratio of the cis conformer, and the ratio correlates well with the Hammett sigma values of the substituents. These steric properties can be applied to achieve amide conformational switching by protonation at the aromatic substituent of 4-[bis(dimethylamino)]-N-methylacetanilide or N-[p-(dimethylamino)phenyl]-N-phenylacetamide.     

Nonlinear optical side‐chain polymers post‐functionalized with high‐β chromophores exhibiting large electro‐optic property

Electro‐optic side‐chain polymers have been synthesized by the post‐functionalization of methacrylate isocyanate polymers with novel phenyl vinylene thiophene vinylene bridge (FTC) nonlinear optical chromophores. For this application, FTC‐based chromophores were modified in their electronic donor structure, exhibiting much larger molecular hyperpolarizabilities compared with the benchmark FTC. Of these new chromophores, absorption spectra, hyper‐Rayleigh scattering experiment, and thermal analysis were carried out to confirm availability as effective nonlinear optical units for electro‐optic side‐chain polymers. The electro‐optic coefficients (r₃₃) of obtained polymers were investigated in the process of in situ poling by monitoring the temperature, current flow, poling field, and electro‐optic signal. Compared with the nonsubstituted analogue, benxyloxy modified FTC chromophore significantly achieved higher nonlinear optical property, exhibiting molecular hyperpolarizability at 1.9 μm of 4600 × 10^?30 esu and an r₃₃ value of 150 pm/V at the wavelength of 1.31 μm. Synthesized electro‐optic polymers showed high glass transition temperature (T_g), so that the temporal stability examination exhibited >78% of the electro‐optic intensity remaining at 85 °C over 500 h. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Rhodium‐ and ruthenium‐complex‐catalyzed condensation of ferrocene‐containing dithiols and diols with diarylsilanes to give silaferrocenophanes and ferrocene polymers

1,1′‐Ferrocenedithiol reacts with di(4‐methoxyphenyl)silane, diphenylsilane, and di(4‐fluorophenyl)silane in the presence of RhCl(PPh₃)₃ catalyst to give mixtures of 2,2‐diaryl‐1,3‐dithia‐2‐sila[3]ferrocenophanes (1a–3a) and ? (Fc? S? SiAr₂? S) _n? (Fc = 1,1′‐ferrocenylene; 1b: Ar = C₆H₄OMe‐4; 2b: Ar = Ph; 3b: Ar = C₆H₄F‐4). The products are isolated and characterized by NMR spectroscopy and elemental analyses. The polymers 1b–3b, obtained from a toluene‐soluble fraction of the products, show GPC elution patterns corresponding to M_n values of 2700–4600 (polystyrene standards). The UV–vis spectra of the ferrocenophanes and polymers exhibit a d–d transition peak at about 440 nm, while the polymers show a π–π* transition peak at 320–330 nm. The cyclic voltammograms of 3a (Ar = C₆H₄F ? 4) and 3b show a reversible redox of the iron center at 0.27 V and 0.35 V (Ag⁺/Ag) respectively. Reaction of 1,1′‐ferrocenedimethanol with diphenylsilane in the presence of RuCl₂(PPh₃)₃ catalyst results in selective formation of 3,3‐diphenyl‐2,4‐dioxa‐3‐sila[5]ferrocenophane ( 4 ), whose structure was determined by X‐ray crystallography. Copyright © 2001 John Wiley & Sons, Ltd.     

Azo benzene derivatives

Pressure-volume isotherms for 4-(trans-4-butylcylohexyl)benzonitrile were measured by means of piston-cylinder method. This substance has a monotropic nematic phase at atmospheric pressure. But over a pressure, the nature of isotropic to nematic phase transition changed from monotropic to enantiotropic phase transition. It is the first observation in P-V-T experiments that the monotropic isotropic-nematic transition changes enantiotropic under pressure.     

The most favorable condition for lipid hydrolysis by Rhizopus delemar lipase in combination with a sugar–ester and alcohol W/O microemulsion system

The hydrophobic interfacial characterization of sugar–ester alcohol W/O microemulsion was investigated in order to develop a suitable design for reaction media. A W/O microemulsion system was prepared as a combination of sugar–ester, DK-ester-F-110 with alcohol as a cosolvent. The diameter of the sub-micron-sized water pool, the hydrophobicity of the water pool, and the fluidity of the micro-interface were studied to analyze the reactivity of Rhizopus delemar lipase in lipid hydrolysis. The diameter of the sub-micron sized water pool was measured by dynamic laser light scattering. It was proportional to the 0.33 power of W_soln and decayed with increasing alcohol concentration. The initial reaction rate of the hydrolysis of triolein in W/O microemulsion depended on the solubilized water content. The hydrophilic character of the micro-water pool was estimated from the fluorescence wavelength indicated by Coumarin 343. The maximum initial reaction rate appeared at 450–460 nm. The fluidity of the micro-interface was investigated by fluorescence anisotropy using TMA-DPH. A suitable physicochemical reaction condition for high reactivity to occur was found, satisfying both the hydrophilicity and the fluidity of the micro-interface.     

Separation and control of the elution order of N-t-butyloxycarbonyl amino acids D/L isomers by reversed-phase HPLC using cyclodextrins as chiral selectors for the mobile phase.

The enantiomeric resolution of N-t-butyloxycarbonyl (N-t-Boc) amino acids D/L isomers by reversed-phase HPLC was investigated using cyclodextrins (CD's) as chiral selectors for the mobile phase. The use of a low pH (pH<4) for the mobile phase enabled the enantioseparation of N-t-Boc amino acids. The opposite elution order of D/L isomers was observed when hydroxypropyl-derivatized beta-CD was used instead of native beta-CD. A computer simulation of the enantioseparation showed that the ratio of the retention factors of the chiral selector and the sample determined the elution order and the resolution. When the retention factor of the chiral selector is smaller than that of the sample, an isomer having larger complex formation constant eluted faster. However, when the chiral selector had a larger retention factor than the sample, an opposite elution order of the isomers was obtained. The large difference in the retention factors between the chiral selector and the sample led to good enantiomeric separation.     

A microsensor for adenosine-5′-triphosphate pH-sensitive field effect transistors

The sensor for adenosine-5′-triphosphate (ATP) is based on H⁺-ATPase immobilized via a polyvinylbutyral resin on a pH-sensitive field effect transistor. A linear relationship was obtained between the initial rate of change of the differential gate output voltage and the logarithm of the ATP concentration over the range 0.2–1.0 mM ATP. The optimum pH was 9.0 at 40°C but pH 7.0 was preferred for routine measurements. Only slight responses were obtained for 1 mM glucose, creatinine or urea. The ATP-sensing system exhibited a response to 1 mM ATP for at least 18 days.     

Direct electron transfer with glucose oxidase immobilized in an electropolymerized poly( N-methylpyrrole) film on a gold microelectrode

Direct electron transfer between active glucose oxidase (GOD) and a gold electrode was obtained when GOD was immobilized in poly(N-methylpyrrole) electrochemically prepared on the gold electrode. When electropolymerization was accomplished at 50 °C, after glucose addition, the cyclic voltammograms showed an increased oxidation peak at ca. ?0.45 V vs. Ag/AgCl. This potential corresponds to the oxidation potential for FADH₂. Although the GOD becomes much less selective, a glucose-dependent current response is obtained.