Liberal Studies

A Solvate of the Diacetate Salt of the Octaethyltetraphenylporphyrin Dication, H₄OETPP²⁺.2CH₃COO^-.3CH₃COOH.- CH₂CI₂

K. M. Barkigia et al. — Mon, 29 Mar 2010 09:19:57 PDT

The structure of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,-20-tetraphenylporphyrin(2+) diacetate acetic acid dichloromethane solvate, C₆₀H₆₄N₄²⁺.2C₂H₃O₂-.3C₂H₄-O₂.CH₂CI₂, has been determined at 200K. The molecule is severely non-planar and adopts an $4 saddle shape. It is the most distorted member of the OETPP series reported to date, with displacements of the β- pyrrole C atoms from the plane of the four N atoms as great as 1.42 Å, and acute tilts of the phenyl rings relative to the porphyrin plane. The two acetate counterions act as bidentate ligands which bond to the H atoms on opposite pairs of N atoms. The crystal lattice also contains three acetic acid molecules of solvation per porphyrin molecule, all of which are involved in hydrogen bonds to the acetate molecules. An 'innocent' molecule of CH₂CI₂ is also present.

Expression of Anthocyanins in Callus Cultures of Cranberry (Vaccinium macrocarpon Ait)

D. L. Madhavi et al. — Mon, 29 Mar 2010 09:19:55 PDT

Expression of anthocyanins and other flavonoids in callus cultures established from different parts of cranberry plant was investigated and the effect of explant source on the in vitro product was determined. Callus cultures were initiated from different parts of the plant in a modified Gamborg's medium with 5.37 μM α-naphthaleneacetic acid, 0.45 μM 2,4-dichlorophenoxyacetic acid, and 2.32 μM kinetin in the dark at 25°C. Callus cultures accumulated anthocyanins only on exposure to light and maximum concentration was observed by day 12. The cultures had lower levels of anthocyanins and only cyanidin 3-galactoside, cyanidin 3-glucoside, and cyanidin 3-arabinoside were identified in all cultures regardless of source of explant. Proanthocyanidin accumulation in cultures was independent of light, and levels were higher than in mature fruit. Exposure to light induced accumulation of flavonols and enhanced activity of phenylalanine ammonia-lyase in the cultures.

Anthocyanin Pigments: Comparison of Extract Stability

Alan Baublis et al. — Mon, 29 Mar 2010 09:19:54 PDT

Stabilities of anthocyanins from Concord grapes, red cabbage, tradescantia and ajuga were studied. RP-HPLC analysis was used to characterize individual anthocyanins and spectrophotometric analysis for all pigments. Anthocyanins from tradescantia were much more stable than the other extracts. Such increased stability was attributed to its intrinsic nature.

Radiation Chemistry of Overirradiated Aqueous Solutions of Hydrogen Cyanide and Ammonium Cyanide

Z. D. Draganić et al. — Mon, 29 Mar 2010 09:19:52 PDT

The radiolysis of aqueous solutions (O₂-free) of HCN and NH₄CN was examined at very large doses of ⁶⁰Co gamma radiation (up to 230 Mrad). In this dose range the cyanide initially present (0.12 M) is decomposed and only its radiolytic products participate in the radiation-induced chemical process. It has been found that the weight of the dry residue containing the mixture of nonvolatile radiolytic products increases as doses increase up to 40 Mrad (up to about 4 g/l), but with further dose increases remains practically unchanged (NH₄CN) or decreases slightly (HCN). Carboxylic and amino acids are present in overirradiated samples. At increasing doses their concentrations decrease, with the exception of oxalic and malonic acids, which are continually produced and accumulate. This is also the case with the abundant NH₃ and CO₂, as well as with several other products that were generated at lower radiation-chemical yields. The molecular weights of the radiolytic products are up to 20,000 daltons throughout the dose range studied. Their amounts gradually change with increasing doses above 30 Mrad: The compounds with M_w between 2,000 and 6,000 daltons become more abundant, while the amounts of polymers with M_w between 6,000 and 20,000 decrease. The relevance of these findings for studies of chemical evolution is considered.

Tetracycloalkenyl-meso-tetraphenylporphyrins as Models for the Effect of Non-planarity on the Light Absorption Properties of Photosynthetic Chromophores

Craig J. Medforth et al. — Mon, 29 Mar 2010 09:19:50 PDT