SYNTHESIS OF PORPHYRINS TAILORED WITH 8 FACIALLY-ENCUMBERING GROUPS -AN APPROACH TO SOLID-STATE LIGHT-HARVESTING COMPLEXES

Citation
Rw. Wagner et al., SYNTHESIS OF PORPHYRINS TAILORED WITH 8 FACIALLY-ENCUMBERING GROUPS -AN APPROACH TO SOLID-STATE LIGHT-HARVESTING COMPLEXES, Tetrahedron, 50(38), 1994, pp. 11097-11112
Citations number
62
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
ISSN journal
00404020
Volume
50
Issue
38
Year of publication
1994
Pages
11097 - 11112
Database
ISI
SICI code
0040-4020(1994)50:38<11097:SOPTW8>2.0.ZU;2-9
Abstract
Synthetic models of the photosynthetic antenna complexes must achieve long-range 3-dimensional order encompassing a large number of porphyri nic pigments with limited direct contact of the pigments. In order to develop solid-state antenna complexes, we have synthesized porphyrins bearing benzyloxy groups projecting over both faces and optionally als o around the periphery of the porphyrin. Routes have been established for prefunctionalizing benzaldehydes with various benzyloxy groups. Re action of 2,6-bis, 3,5-bis, or 2,4,6-tris(benzyloxy)benzaldehydes with pyrrole via the room temperature two-step one-flask porphyrin reactio n provides direct access to the facially-encumbered porphyrins. The be nzyloxybenzaldehydes react as efficiently as methoxybenzaldehydes, ind icating the utility of the -OCH2- unit for introducing large substitue nts near the face of the porphyrin. The octakis and dodecakis(benzylox y)porphyrins exhibit characteristic porphyrin absorption and fluoresce nce properties in solution. The crystal structure of meso-tetrakis[2,6 -bis(2,3 4,5,6-pentafluorobenzyloxy)phenyl] porphyrin has been determi ned. The pentafluorobenzyloxy substituents provide a cavity on each si de of the porphyrin plane which has an approximate cylindrical shape w ith a diameter of similar to 7.5 Angstrom and a height of greater than or equal to 4.5 Angstrom. The porphyrin core parameters are those obt ained for free base derivatives in which the inner hydrogen atoms are ordered. Crystal data: a = 14.759(1) Angstrom, b = 25.519 (2) Angstrom , c = 13.100(1) Angstrom, alpha = 100.04(1), beta = 99.83 (1), gamma = 88.25(1), V = 4767.3 (6) Angstrom(3), all measurements at 127 K, tric linic, space group P-1(-), Z = 2 R(1)(F) = 0.097, for 10020 ''observed '' data, and wR(2)(F-2) = 0.275 for 17761 total unique (all) data.