The synthesis of the acyclic Schiff bases H4L7 and H2L8, derived from 1-(pyrrol-2-yl)butane-1,3-dione and 1,3-bis(2-aminophenoxy)propane, and from pyrrole-2-carbaldehyde and 3,6-dioxaoctane-1,8-diamine, respectively are reported, together with their respective copper(II) complexes. Crystals of [Cu(H2L7)] are monoclinic; R= 0.0549 for 1 901 observed reflections. The copper is co-ordinated in the inner (N2O2) compartment with a trans mode of attachment by the ligand; the approximately square-planar co-ordination geometry shows a significant tetrahedral distortion. The pyrrole and ether functions are not bonded to the copper. In the structure of [Cu(HL8)(O2CMe)](R= 0.0363, 4 800 reflections), the co-ordination geometries of the copper atoms in the two independent molecules are tetragonally-distorted octahedral, the two long axial bonds being to one acetate oxygen and to one of the ether oxygen atoms; one pyrrole residue is not co-ordinated to copper.
The reaction of 2,6-diacetylpyridine with 1,3-diamino-2-hydroxypropane in methanol in the presence of lead(II) cations leads to the isolation of lead(II) complexes of an oxazolidine-containing Schiff base macrocycle formed by ring-contraction; the ligand is hexadentate and the lead is N-bonded to one thiocyanate to form a monocationic complex.
Dermal absorption of the lipophile and potential carcinogen benzo[a]pyrene (BaP) in soils from contaminated sites was simulated in vitro using human skin exposed to 14C-BaP-spiked soil. This study is the first in a series of tests at Health Canada with several soil contaminants spanning a wide range of lipophilicity conducted with viable human skin. Breast skin was obtained fresh from a local hospital and dermatomed to a thickness of 0.4-0.5 mm. Teflon Bronaugh diffusion cells were perfused with HEPES buffered Hanks saline (pH 7.4) with 4% bovine serum albumin (BSA) and fractions were collected at 6-h intervals for up to 24 h exposure either to 14C-BaP applied in acetone or spiked in a commercial gardening soil. As skin depot 14C levels were still high at 24 h, the study was repeated for up to 42 h to examine skin depot bioavailability. Skin was washed with soapy water at 24 h in both the 24- and 42-h studies. Exposure to 14C-BaP both with and without soil was conducted in triplicate with skin specimens from at least 4 patients. In the 24-h exposure tests including the skin depot there was 15 and 56% absorption with and without soil, respectively. The lower total percent absorption from the spiked soil applied to skin resulted from lower depot absorption of 8% with and 45% without soil. Data for 42-h studies were similar and revealed no significant decrease in skin depot levels. Including the 42-h depots there was 16 and 50% absorption with and without soil, respectively, with respective depots of 7 and 39%. As there was no significant difference between the 24- and 42-h depots both with and without soil, the data suggest the depot for BaP was not bioavailable for at least the additional 18-h post soap wash exposure. The bioavailability of BaP is discussed in relation to previous in vitro and in vivo studies in perspective with dermal exposure to contaminated soils.
Dermal absorption of human breast skin obtained fresh from a local hospital was tested before and after freezer storage at -19 degrees C for 30 or 60 d. Dermatomed skin (0.4-0.5 mm) was tested in vitro using the Bronaugh flow-through diffusion cells perfused at 1.5 ml/h with receiver solution (Hanks HEPES buffered basal saline containing 4% bovine serum albumin [BSA]). Six 14C-radiolabeled chemicals ranging in lipophilicity were tested, including benzo[a]pyrene (BaP), ethylene glycol (EG), methyl parathion (MP), naphthalene (Nap), nonyl phenol (NP), and toluene (Tol). There was significantly lower percent dermal absorption into the receiver solution for two of the six chemicals (BaP and Tol) with the skin depot excluded. However, with percent dermal absorption defined as that including the skin depot, with the exception of the BaP data for skin frozen 30 d, there was no significant difference between percent dermal absorption data for fresh unfrozen controls and those stored frozen for all 6 test chemicals for both 30 and 60 d freezer storage times. These results suggested with skin depot included that freezer storage may have potential for preserving human skin for in vitro absorption tests of environmental contaminants; however, optimal freezer storage conditions such as temperature and storage duration and their effects on skin viability and dermal metabolism need to be determined.
Abstract Treatment of appropriate Schiff bases with copper(II) ethanoate in the presence of a bridging ligand X results in the formation of complexes of type (I) and (II).
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