74688-74-7Relevant academic research and scientific papers
Inverse Triphenylmethylium Dyes
Hellwinkel, Dieter,Gaa, Heinrich Georg,Gottfried, Reiner
, p. 1045 - 1060 (2007/10/02)
When in the conventional triphenymethylium dye systems of the crystal violet and malachit green type, 6 and 7, the N-donor and C(+)-acceptor centers are interchanged, the "Inverse Triphenylmethylium Dye Types" 4 and 5 are obtained, showing very similar colors.The stable models with R = phenyl (8 - 10) and R = p-tolyl (11 - 13) were investigated in more detail.The visual observations were supported by the VIS spectra which showed nearly the same longest wavelength absorption maxima for corresponding pairs of inverse and conventional dye representatives.The experimental results can be interpreted with a simple HMO-model according to which the longest wavelength absorptions correspond here to transitions of equal energy from weakly bonding to nonbonding and from nonbonding to weakly antibonding molecular orbitals, respectively.On the same basis numerous isoelectronic variants of that dye type can be envisaged.In the NMR-spectra of the new dyes, characteristically increasing deshieldings of nearly all positions are observed in going from the mono- (10(+), 13(+)) through the di- (9(++), 12(++)) to the trications (8(+++), 11(+++)). - Key words: Dyes, Di-, Tricarbeniumions, NMR Spectra, VIS Spectra
