The Synthesis and Recognition Properties of Chiral Porphyrins and Chiral Bis-Porphyrins
Master of Science (MS)
Date of Award
This thesis has a dual focus. The design, synthesis and anion recognition properties of six novel chiral zinc (II) bisporphyrin hosts with architectures resembling the corner of a box are reported. Four of these bisporphyrin hosts were synthesized from tetraphenyl porphyrin platforms using commercially-available chiral pyrrolidine ring systems (R- or S- pyrrolidin-2- nylmethamine and R- or S-pyrrolidin-3-amine) as spacers; whereas (R,R)- and (S,S)- cyclohexane-1,2-diamine ring systems were employed as spacers in synthesis of the remaining two chiral bis-porphyrins. As suggested by molecular models, the two porphyrin rings represents two perpendicular walls of a corner and the pyrrolidine / cyclohexane ring systems represents the third wall of the chiral corner. Screening for guest recognition of the two types of bisporphyrin hosts by UV / Vis titrations with derivatized dicarboxylate guests of varying chain lengths (-O2C-(CH2)n-CO2 - , n = 0-6) as well as diamines revealed the optimal distance for simultaneous binding to both metallo centers to be n = 3 (5 carbons’ length) for bisporphyrins with the pyrrolindin-3-amine spacers, and n =1 (3 carbons’ length) for those with the pyrrolidin2-nylmethamine spacers. A selectivity of ~5-7 was exhibited by the receptors with pyrrolindin-3- amine spacers with glutarate, and the pyrrolidin-2-nylmethamine bisporphyrins recorded a selectivity of ~4 with malonate. The cyclohexane hosts however did not bind any of the guest molecules studied in this work. Also, in this work, the synthesis and characterization, as well as a model for a priori prediction of guest-binding properties of two hosts with predicted introverted functionality is discussed. The hosts are hybrids of tetraphenyl zinc porphyrin and the o-isocyanatoaniline derivatives of (R)- and (S)-N-(4-fluorophenyl)piperidine-3-carboxamide. It was predicted that the S-receptor would bind S-mandalate preferentially, while the R-receptor would bind R-mandalate. All the hosts reported in this work were characterized by Nuclear Magnetic Resonance (NMR) spectroscopy and Electrospray Ionization Mass Spectrometry (ESI-MS).
Stephen D. Starnes
Chemistry | Physical Sciences and Mathematics
Boateng, Elvis Duah, "The Synthesis and Recognition Properties of Chiral Porphyrins and Chiral Bis-Porphyrins" (2014). Electronic Theses & Dissertations. 562.