title: Protonated N-confused porphyrin dimer: formation, structure, and guest binding.
abstract: The protonation of 3,3'-bis(meso-tetratolyl-2-aza-21-carbaporphyrin) with various acids was studied. The stepwise formation of mono-, di-, and tetracationic species was shown on the basis of UV-vis-near-IR and low-temperature (1)H NMR. Upon going from di- to tetraprotonated form, the bis(porphyrinoid) skeleton changes its conformation from cisoid to bent-transoid, which was found by single-crystal X-ray analyses, 2D NMR, and density functional theory (DFT) calculations. The formation of cation-anion complexes was established in both the solid state and solution. The substitution of anions was studied by spectrophotometric and (1)H NMR titrations. A pronounced decrease of the HOMO-LUMO gap in the tetraprotonated species was shown by cyclovoltametry and time-dependent DFT calculations.
authors.affiliation: Department of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50 383 Wrocław, Poland. pjc@wchuwr.pl
authors.forename: Piotr J
authors.initials: PJ
authors.lastname: Chmielewski
authors.forename: Marta
authors.initials: M
authors.lastname: Siczek
authors.forename: Ludmiła
authors.initials: L
authors.lastname: Szterenberg
mesh_terms: D000143:Acids / Q000737:chemistry; D001665:Binding Sites; D018360:Crystallography, X-Ray; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011166:Porphyrins / Q000138:chemical synthesis / Q000737:chemistry*; D011522:Protons; D011789:Quantum Theory
chemical_list: D000143:Acids; D011166:Porphyrins; D011522:Protons