Structure, correlation with source

Correlation of Structure with Source. Allochthonous-derived DOM (8) was isolated from the Suwannee River at its origin in the Okefe-nokee Swamp in southern Georgia. The fiilvic acid fraction, which is responsible for the black coloration of the water, was extensively characterized (9). Several average molecular models based on quantitative analytical data were presented in that report (10) to denote the mixture characteristics of fiilvic acid. One model, modified to depict biochemical sources and based on quantitative analytical data (10), is presented in Structure 1. Other models of Suwannee River fulvic acid (based on lignins, terpenoids, tannins, and flavonoid sources) were previously proposed (II). 

In the present study, the complex, tetra(imidazole)chlorocopper(II) chloride, [Cu(imidazole)4Cl]Cl, has been synthesized, and the structure has been determined at the Small Crystal X-ray Crystallography Beamline (11.3.1) of the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL)(Fig.l)[7]. Structural parameters are compared to similar compounds previously reported in the literature. The particles in the present study can be used to prepare nanoparticle materials, or the crystals can be grown under conditions to form nanoparticles or nanoparticle clusters. The molecular structure of the complex here can be used as a model to correlate with its magnetic and electronic properties. Structural parameters for the present complex of copper(II) are compared to similar compounds previously reported in the literature. With the data accumulated here, some previously unexplained bioinorganic chemistry and related phenomena may be explained in the context of the compounds molecular and electronic properties. 

Hexahelicene is a chiral hydrocarbon with a helical structure. We found that (P)-hexahelicene with 0.13% ee, a lower ee than that induced by CPL [3,80], acts as a chiral initiator for asymmetric autocatalysis (Scheme 11). The reaction between pyrimidine-5-carbaldehyde 11 and i-Pr2Zn gave (S)-pyrimidyl alkanol 12 with 56% ee [83]. On the other hand, when (M)-hexahelicene with 0.54% ee was used instead of (P)-hexahelicene, (P)-12 with 62% ee was formed. As already described, these ee can be enhanced by further asymmetric autocatalysis. Thus, the chirality of CPL has been correlated with that of alkanol 12 with high ee by using hexahelicene as the chiral source of asymmetric auto catalysis. 

The structure of lagascol (42), from Sideritis serrata,45 was defined by a correlation with the 1 la-alcohol, lagascatriol, previously obtained from this source. 

X-ray powder diffraction has been the primary tool used in zeolite structure research. With new high-flux sources, the size requirement of useful single-crystals for structure determination studies has decreased significantly. In addition, refinements of atomic coordinates of known structures using Rietveld powder techniques have become common (24). The solution of a dozen or more new zeolite structure types within the last several years has added to our knowledge base for looking at unknowns (for examples, see references 25-31), and has made us better able to characterize catalyst materials and to correlate synthesis, sorptive, catalytic, and process parameters to their structures (32,33). 

Two other alkaloids, ephedradine C (192) and ephedradine D (193), were isolated from the same source (mao-kon) (132,133). Their structure elucidations were based mainly on spectroscopic evidence. Additionally, 192 was correlated with 191 by treatment with diazomethane. The figures below representing all three alkaloids show their absolute configuration. 

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