The Development of Highly Fluorescent Hemicyanine and Dicyanoisophorone Dyes for Applications in Dye-Sensitized Solar Cells

Journal of Fluorescence - Ruthenium-based metal complex dyes have been employed extensively in dye-sensitized solar cells (DSSCs) as photosensitizers, but the cost and toxicity of metal complexes...     

Twisted imide bond in noncyclic imides. Synthesis and structural and vibrational properties of N,N-bis(furan-2-carbonyl)-4-chloroaniline

A novel imide compound (C(16)H(10)ClNO(4)) was synthesized in a single step by the reaction of 2-furoic acid with 4-chloroaniline in a 2:1 molar ratio using carbonyldiimidazole (CDI) in dry THF. The structure was supported by spectroscopic and elemental analyses and the single-crystal X-ray diffraction data. Crystallographic studies revealed that the compound crystallized in a monoclinic system with space group P2(1)/c and unit cell dimensions a = 12.2575(5) ?, b = 7.7596(2) ?, c = 15.0234(7) ?, α = γ = 90°, β = 92.771(4)°, V = 1427.25(10) ?(3), Z = 4. The imide bond is twisted, and the O═C-N-C(O) units deviate significantly from planarity with dihedral angles around the imide group reaching ca. -150.3° (C1-N1-C2-O21 = -148.8° and C2-N1-C1-O11 = -151.9°). The nonplanarity of the imide moiety and the related conformational properties are discussed in a combined approach that includes the analysis of the vibrational spectra together with theoretical calculation methods, especially in terms of natural bond orbital (NBO) calculations.     

Synthesis,Characterization and Fluorescence Studies of Novel Tetrachloroperylene-Azo Hybrid Dyes

Novel rylene-azo hybrid dyes have been synthesized by condensation of azo-dyes with tetrachloroperylene dianhydride, possessing stupendous thermal, chemical and photochemical stability. Phenolic azo dyes are used for the nucleophilic replacement of chlorine substituents at 1,6,7,12-positions of perylene 3,4,9,10-dianhydride system. The absorption maxima (?_max) of these dyes have been determined in diverse solvents such as water, ethanol, methanol, ethyl acetate and N, N-dimethylformamide. Fluorescence spectra are taken in water and highest fluorescence was exhibited by dyes containing carboxylic groups. The ?_max and fluorescence of these dyes is greatly affected by polarity of solvents. The structures of newly synthesized rylene-azo hybrid dyes have been confirmed by UV, FTIR and ¹HNMR spectroscopy.     

The CYPome of Sorangium cellulosum So ce56 and identification of CYP109D1 as a new fatty acid hydroxylase

The first systematic study of the complete cytochrome P450 complement (CYPome) of Sorangium cellulosum So ce56, which is a producer of important secondary metabolites and has the largest bacterial?genome sequenced to date, is presented. We describe the bioinformatic analysis of the So ce56 cytochrome P450 complement consisting of 21 putative P450 genes. Because fatty acids play a pivotal role during the complex life cycle of myxobacteria, we focused our studies on the characterization of fatty acid hydroxylases. Three novel potential fatty acid hydroxylases (CYP109D1, CYP264A1, and CYP266A1) were used for detailed characterization. One of them, CYP109D1 was able to perform subterminal hydroxylation of saturated fatty acids with the support of two autologous and one heterologous electron transfer system(s). The kinetic parameters for the product hydroxylation were derived.     

Sodium borohydride reduction of aromatic carboxylic acids via methyl esters

A number of important aromatic carboxylic acids precursors, or intermediates in the syntheses of natural products, are converted into methyl esters and reduced to the corresponding primary alcohols using a sodium borohydride-THF-methanol system. The alcohols are obtained in 70–92% yields in 2–5 hours, in a pure state. This two-step procedure not only provides a better alternative to aluminum hydride reduction of acids but also allows the selective reduction of esters in presence of acids, amides, nitriles or nitro functions which are not affected under these conditions.     

Microwave‐Assisted Synthesis of cAMP Phosphodiesterase Inhibitor 8‐Hydroxy‐6,7‐dimethoxy‐3‐hydroxymethylisocoumarin

An efficient microwave‐assisted synthesis of 8‐hydroxy‐6,7‐dimethoxy‐3‐hydroxymethyl isocoumarin (1), a metabolite of Streptomyces mobaraensis and structural relative of reticulol and cytogenin that possesses potent cyclic nucleotide phosphodiesterase inhibitor activity, is described. 3,4,5‐Trimethoxyhomophthalic acid (2) was condensed with acetoxyacetyl chloride under microwave irradiation and the acid hydrolysis of resulting 6,7,8‐trimethoxy‐3‐acetoxymethylisocoumarin (3) afforded the 6,7,8‐trimethoxy‐3‐hydroxymethylisocoumarin (4). Regioselective demethylation of the latter using magnesium iodide in THF yielded the title compound (1).     

Br...O contacts and π–π stacking dominate the packing in methyl 4‐bromo‐3,5‐dimethoxybenzoate

The title compound, C₁₀H₁₁BrO₄, a useful precursor to pharmaceutically active isocoumarin and isochroman derivatives, crystallizes with two unique molecules in the asymmetric unit. A π–π stacking interaction links the planar molecules in the asymmetric unit. Additional π–π contacts stack pairs of molecules along the c axis. A feature of the crystal packing is the presence of a number of short Br...O contacts. A particularly unusual arrangement involves the formation of dimers, with pairs of Br...O contacts imposing a close Br...Br interaction and generating five‐membered rings within an eight‐membered ring formed by two Br...O contacts. Only two comparable arrangements have been reported previously. The Br...O contacts combine with weak C—H...O hydrogen bonds to form corrugated sheets of molecules approximately parallel to (001). These sheets are stacked along the c axis by π–π interactions to generate a three‐dimensional network.     

Polyethylene glycol clicked Co(II) Schiff base and its catalytic activity for the oxidative dehydrogenation of secondary amines

Copper catalyzed [3+2] cycloaddition "click method" provided an efficient and high yielding immobilization of cobalt(II) Schiff base to the azido-functionalized MeOPEG(5000); whereas the direct reaction between MeOPEG(5000) and Co(II) Schiff base did not produce any immobilization. The prepared catalyst was tested for the oxidative dehydrogenation of various secondary amines using TBHP as oxidant and could be easily recovered by precipitation with diethyl ether at the end of the reaction.