121st General Meeting of the KCS

Type Poster Presentation
Area Organic Chemistry
Room No. Event Hall
Time 4월 19일 (목요일) 11:00~12:30
Code ORGN.P-462
Subject Expanded porphyrin analogues: Dibenzohexaphyrins Containing Four Exocyclic Double Bonds at meso-Positions
Authors Seong-Jin Hong, hyun seong kang, Chang Hee Lee*
Department of Chemistry, Kangwon National University, Korea
Abstract The novel meso-alkylidenyl porphyrinoids are non-aromatic and conformationally flexible macrocycles displaying unusual prototropy and unique protonation selectivity depending on the number of core-hydrogen. Most of the reported meso-alkylidenyl porphyrinoids displayed site-selective protonation and pyrrole inversion in some cases. For example, the compounds containing no core hydrogen are protonated at core nitrogen. However, the compounds bearing core-hydrogens are protonated at meso-(α)-position with concomitant hypsochromic shift of the absorption maxima. As a part of our endeavor for the construction of the new expanded porphyrinoid macrocycles, we have synthesized expanded meso-alkylidenyl dibenzohexaphyrins and fully characterized by 1H NMR and HRMS spectroscopy as well as the single crystal X-ray diffraction analysis. The synthesis was accomplished by a typical ‘3+1’ type of the mixed condensation. Synthesized compounds contain multiple exocyclic carbon-carbon double bonds at meso-positions. The p-benzihexaphyrin adopts two pyrroles inverted geometry with the intramolecular hydrogen bonding between pyrrolic N-H and carbonyl moiety of the indanedione. In case of m-benzihexaphyrin, the intermediate macrocycle bearing meso-hydroxy groups was isolated and characterized. The crystal structure analysis indicates that the molecules adopts ci symmetry with cylindrical shape through four intramolecular hydrogen bonding between pyrrole NHs and carbonyl group of indanedione. In this presentation, Synthesis, structural characteristics and protonation selectivity studies will be presented.
E-mail chhlee@kangwon.ac.kr