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The reaction of diiminoisoindoline with amine-terminated polyethers results in the formation of phthalocrown macrocycles. For n = 1 (where n is the number of ether units), a 2 + 2 condensation takes place, but for n = 2 and 3, a 1 + 1 macrocyde formation occurs. The n = 2 phthalocrown is particularly stable due to a strong intramolecular hydrogen bond, but the n = 3 ring hydrolyzes to form a 3-imino-l-oxoisoindoline derivatized crown ether species. For the n = 1 phthalocrown, we observed dynamic behavior in the ¹H NMR spectrum, and using VTNMR were able to measure a ΔG = 44.6 kJ/mol for proton exchange. [ABSTRACT FROM AUTHOR]

Phlorins bearing different substituents at the sp³-hybridized meso-position were investigated. The extent to which different substituents at this unique position can influence phlorin spectroscopic properties, structure, and stability is of interest given that such substituents are not in direct conjugation with the phlorin macrocycle. While the effect of various substituents at the sp2-hybridized positions has been the subject of prior investigations, the impact of different substituents at the saturated carbon atom has not been systematically examined. In this study, phlorins with different combinations of geminal methyl and phenyl substituents were prepared in yields of 24-49% via dipyrromethane + dipyrromethanedicarbinol routes, and their NMR spectra, UV-vis spectra, X-ray crystal structures, and stability toward light and air were compared. The nature of the substituents at the sp³-hybridized position was found to impact spectroscopic properties, structure, and stability to varying degrees. Thus, the choice of substituents at the sp³-hybridized meso-position provides a further option for altering phlorin properties. [ABSTRACT FROM AUTHOR]