The Modernization of the Chinese Salt Administration, 1900-1920. By S. A. M. Adshead. Cambridge, Mass., Harvard University Press, 1970. Pp. xi + 280. $8.75.

Expanded Porphyrins and Their Heterologs

“…For instance, evidence for the formation of the hexamethylsmaragdyrin 323 has, so far, only come from the presence of a strong Soret absorption at ca . λ max = 450 nm, and additional broad bands in the 700−725 nm region in the electronic spectra of the reaction solutions. , Attempts to isolate the corresponding metallo complexes were further hampered by their extreme sensitivity toward light and acid.

…”

“…The sapphyrins 1, so-called due to their intense blue-green color, were the first known examples of the expanded porphyrins. Initially discovered serendipitously by Woodward more than 30 years ago 1,2 during the course of earlier attempts toward the synthesis of vitamin B 12 , and later isolated in small quantities (as the 25,29-dioxasapphyrins) as by products in the synthesis of 21,24-dioxacorroles by Grigg's group in Nottingham. 3,128,129 As originally formulated by Woodward, they constitute a series of 22π-electron pentapyrrolic macrocycles containing a single direct link and four methine bridges between the pyrrolic subunits.…”

“…The basic strategy in the synthesis of sapphyrins has remained substantially unchanged since Woodward's pioneering work. 1,2,130 As outlined in Scheme 50 it involves a MacDonald-type "3 + 2" condensation between a diformyl bipyrrole such as 139, 167, and 269 and a bis(pyrrolylmethyl)pyrrole diacid, e.g., 271, as the key step. The other approaches of Grigg and Johnson 128,129,131 that followed shortly, essentially mirrored this procedure, while the more recent efforts of Sessler 125,[132][133][134] differed mainly in the efficiency of producing the requisite bipyrrolic and tripyrrane precursors.…”

“…Woodward and his colleagues 1,2 were the first to report the probable existence of an expanded porphyrin, a pentapyrrolic sapphyrin (1), and but for the beautiful blue crystals that were formed one can wonder whether it would have been isolated and studied in the mid 1960s. It was at this time that the focus of research into pyrrolic macrocycles was to shrink the macrocycle to the chromophore of vitamin B 12 (2) and exploration of the corrin and corrole chromophores. 3 Regardless, the search for expanded pyrrolic macrocycles had begun.…”

Picosecond Dynamics of Energy Transfer in Porphyrin−Sapphyrin Noncovalent Assemblies

“…In this paper, the molecular recognition and energy transfer dynamics of photoactive, noncovalent complexes assembled from carboxylate-bearing porphyrins and anion binding sapphyrins are described . The sapphyrins, originally reported by Woodward and Johnson, − and more recently studied in detail by Sessler, , are pentapyrrolic “expanded porphyrin” macrocycles that differ from their simpler porphyrin “cousins” in several important ways. Containing five, rather than four pyrrole subunits, the sapphyrins do not coordinate cations readily.…”