88535-47-1Relevant academic research and scientific papers
Porphyrins with exocyclic rings. Part 24. Synthesis and spectroscopic properties of pyrenoporphyrins, potential building blocks for porphyrin molecular wires
Gandhi, Virajkumar,Thompson, Michelle L.,Lash, Timothy D.
experimental part, p. 1787 - 1799 (2010/04/06)
Porphyrins with fused pyrene units have been prepared by '2+2' and '3+1' methodologies. Nitration of 1,2,3,6,7,8-tetrahydropyrene, followed by oxidation with DDQ, gave 4-nitropyrene and this condensed with ethyl isocyanoacetate in the presence of DBU or a phosphazene base to generate a pyrenopyrrole ethyl ester. Ester saponification and decarboxylation with KOH in ethylene glycol at 190 °C gave the parent pyreno[4,5-c]pyrrole and this was further condensed with 2 equiv of acetoxymethylpyrroles to afford the corresponding tripyrranes protected at the terminal positions with tert-butyl esters. In a one pot procedure, the ester protective groups were cleaved with TFA and following dilution with dichloromethane, '3+1' condensation with a pyrrole dialdehyde, and dehydrogenation with DDQ, the targeted pyrenoporphyrins were generated in good overall yields. A dialdehyde was also prepared from the pyrenopyrrole intermediate and this reacted to give an opp-dipyrenoporphyrin. The pyrenopyrrole ethyl ester reacted with dimethoxymethane in the presence of an acid catalyst to give a dipyrenopyrrolylmethane, and this was used to prepare an adj-dipyrenoporphyrin using the MacDonald '2+2' approach. The pyrenopyrrole dialdehyde was also used to prepare a porphyrin with fused pyrene and phenanthroline moieties. Although the UV-vis spectra of these new porphyrin systems are unexceptional, pyrenoporphyrins show many of the features necessary for the construction of porphyrin molecular wires.
Spectroscopic and photochemical properties of mononitropyrenes
Braken-van Leersum, A. M. van den,Tintel, C.,Zelfde, M. van't,Cornelisse, J.,Lugtenburg, J.
, p. 120 - 128 (2007/10/02)
The influence of the nitro group on the aromatic ?-system of pyrene has been studied by comparing the spectroscopic and photochemical properties of the three mononitropyrenes.Whereas the UV and mass spectra of 1- and 4-nitropyrene show an interaction normal for nitro-aromatic compounds, this is not observed for 2-nitropyrene.The lack of interaction is reflected in a UV spectrum very similar to that of pyrene and a mass spectrum with a very low abundance of M-NO.The photochemical behaviour of the three compounds is governed by the degree of interaction. 1-Nitropyrene shows the nitro-nitrite rearrangement leading to 1-hydroxypyrene (88percent) and 1-hydroxy-2-nitropyrene (7percent).The photoproducts of 4-nitropyrene are pyrene (9percent) and unstable products which react with the solvent. 2-Nitropyrene is very stable under photochemical conditions due to lack of interaction.Similarly, the sterically hindered 1-methyl-2-nitropyrene is also very stable towards light.The photochemical nitro-nitrite rearrangement observed for nitro-aromatic compounds was found to be governed by electronic effects.
