title: One-pot synthesis of highly emissive dipyridinium dihydrohelicenes.
abstract: Condensation of a pyridyl-2-carbaldehyde derivative with 2-(bromoethyl)amine hydrobromide gave tetracyclic pyrido[1,2-a]pyrido[1',2':3,4]imidazo-[2,1-c]-6,7-dihydropyrazinium dications in excellent yields. Crystal structures and NOE data demonstrated the helical character of the dications, the dihedral angles between the two pyrido groups ranging from 28-45°. An intermediate in the synthesis was also characterized. A much brighter emission compared to literature helicenes has been found, with quantum yields as high as 60 % in the range of λ=460-600 nm. Preliminary cytotoxicity studies against HT-29 cancer cells demonstrated moderate-to-good activity, with IC50 values 12-30× that of cisplatin.
authors: School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT (UK), Fax: (+44) 113-343-6565 http://www.chem.leeds.ac.uk/People/Halcrow.html.
authors: Amedeo
authors: A
authors: Santoro
authors: Rianne M
authors: RM
authors: Lord
authors: Jonathan J
authors: JJ
authors: Loughrey
authors: Patrick C
authors: PC
authors: McGowan
authors: Malcolm A
authors: MA
authors: Halcrow
authors: Adam F
authors: AF
authors: Henwood
authors: Connor
authors: C
authors: Thomson
authors: Eli
authors: E
authors: Zysman-Colman
keywords: crystal structures; cytotoxicity; fluorescence; helical compounds; voltammetry