Researchers have discovered a macrocyle that they can render aromatic, non-aromatic or anti-aromatic by altering the amount of base they add.
Meso-aryl expanded porphyrins are usually exceedingly twisted structures due to strong hydrogen bonds within them. Even though they contain many conjugated bonds, this twisted structure means that most of these porphyrins are non-aromatic (to be aromatic, a molecule not only needs conjugation, but must also be flat). Previously scientists had added hydrogen ions to disturb hydrogen bonding in porphyrins, causing them to untwist and become aromatic. Here, a team led by Dongho Kim from Yonsei University, Korea, have flattened a porphyrin by removing hydrogen ions. Read the full article in Chemistry World»
Read the original research in ChemComm – it’s free to read until 20 May 2016:
Multifaceted octaphyrin(220.127.116.11.18.104.22.168): deprotonation-induced switching among nonaromatic, Möbius aromatic, and Hückel antiaromatic species
Won-Young Cha, Takanori Soya, Takayuki Tanaka, Hirotaka Mori, Yongseok Hong, Sangsu Lee, Kyu Hyung Park, Atsuhiro Osuka and Dongho Kim
DOI: 10.1039/C6CC02051H, Communication