Absorption spectra of copper and zinc complexes of pheophytins and pheophorbides

Abstract

This study has been made to establish the molar absorbance coefficients of the zinc and copper(II) complexes of the pheophytins and pheophorbides. Spectral curves and metal analyses have been madefor each of the four mentioned chelates of zinc and copper(II) following purification by chromatography. Chelation was accomplished with ease in aqueous acetone solutions of the respective pheophytins and pheophorbides. Thin-layer chromatography procedures, developed during this study, provided reliable indication of the purity of the complexes. Zinc and copper(II) salts and their solutions promoted rapid allomerization of the pigment during chelation. Molar absorbance coefficients are presented.

Geochemistry of Tetrapyrrole, Carotenoid, and Perylene Pigments in Sediments from the San Miguel Gap (Site 467) and Baja California Borderland (Site 471), Deep Sea Drilling Project Leg 63

“…396 to 398 nm and a band I maximum of 641 nm (ethyl ether solvent), precludes a metallo-chlorin identity. That is, while band I maxima of metallochlorins are hypsochromically shifted in relation to that of corresponding free-base chlorins, the Soret position is shifted bathochromically and does not occur below about 420 nm (see Jones et al, 1968). Further, the most conclusive evidence for chlorin(s) 641 not being metallo-chlorins is that this compound(s) extracts into aqueous HC1 (ca.…”

Geochemistry of Tetrapyrrole, Tetraterpenoid, and Perylene Pigments in Sediments from the Gulf of California: Deep Sea Drilling Project Leg 64, Sites 474, 477, 479, and 481, and Scripps Institution of Oceanography Guaymas Basin Survey Cruise Leg 3, Sites 10G and 18G

“…Authentic pheophorbide-a (IV), pheophytin-b, chlorin-e 6 -TME (XVII), desoxomesopyropheophorbide-a (XII), desoxophylloerythrin-ME, and etioporphyrin-I were reacted with cupric sulfate, according to published methods (Jones et al, 1968). In essence, the tetrapyrrole in acetone has added to it a 1/4 volume of IM aqueous CuSO 4 (CuCl 2 in Jones et al, 1968); a few crystals of ascorbic acid were added, the reaction vessel was flushed with nitrogen, and the mixture was stirred in the dark at room temperature for 1 to 1 Vi hours. At the end of the reaction period, the acetone was removed with a stream of nitrogen, water was added, and the pigments were transferred to ethyl ether.…”

In vitro complexes of copper and zinc with chlorophyll

“…[8][9][10] The Chl-HMS complexes may cause an impairment of the photosynthetic function and this, as a final consequence, may lead to death of the plant. 7,8,[15][16][17] Küpper performed experiments in vitro by adding solutions of heavy metals to 96 % ethanolic grass extracts. 8,12 The general reactions of Chl with heavy metals in vitro 11 and in vivo, 13,14 have been already reported.…”