Ethynyl-Bridged Bis-quinolinium Dyes : Studies of the Dependence of Different Types of Conjugation on Spectroscopic Properties

Dicationic bis-quinolinium salts possessing different types of conjugation are presented in which the hetareniums are separated by acetylenic or 1,4-diethynylbenzene spacers. Cross-conjugation is induced by interconnections via the 3-positions of the heteroareniums, and conjugation is realized by 2,2/2,4/4,4-interconnections. We also synthesized mixed cross-conjugated/conjugated 2,3/4,3-interconnected species. The different types of conjugation determine the charge distribution according to the rules of resonance which translate into characteristic C-13 NMR as well as UV-Vis-spectroscopic properties, LUMO geometries, and chemical properties. We found that the triple bond's resonance frequencies are sensitive C-13 NMR spectroscopic indicators for the type of conjugation. Combining cross-conjugated and conjugated structure elements of dicationic bis-quinolinium dyes via triple bonds without additional benzene spacer results in considerable bathochromic shifts of the UV-Vis absorption maxima [Delta lambda(max)approximate to 100 nm]. A charge transfer was calculated from the HOMO of the conjugated into the LUMO of the cross-conjugated partial structure.Peer reviewe

Instruktionale Förderung der Bereitschaft zum argumentativen Denken beim Umgang mit konfligierenden Positionen und fragiler Evidenz

Hefter MH, Hellmann M, Tombrink A, et al. Instruktionale Förderung der Bereitschaft zum argumentativen Denken beim Umgang mit konfligierenden Positionen und fragiler Evidenz. Presented at the 1. Tagung der Gesellschaft für Empirische Bildungsforschung (GEBF), Kiel, Deutschland

How to foster the will to engage in argumentative thinking

Hefter MH, Hellmann M, Tombrink A, et al. How to foster the will to engage in argumentative thinking. Presented at the 15th Biennial Conference of the European Association for Learning and Instruction (EARLI), Munich, Germany