%0 Journal Article
%A Kryman, Mark W.
%A McCormick, Theresa M.
%A Detty, Michael R.
%D 2016
%T Longer-Wavelength-Absorbing, Extended Chalcogenorhodamine
Dyes
%U https://acs.figshare.com/articles/journal_contribution/Longer-Wavelength-Absorbing_Extended_Chalcogenorhodamine_Dyes/3386104
%R 10.1021/acs.organomet.6b00255.s001
%2 https://ndownloader.figshare.com/files/5289997
%K regioselective lithiation
%K dye
%K energy excitation
%K LUMO
%K dimethylamino
%K HOMO
%K DFT
%K Se
%K rhodamine xanthylium core
%K synthesis
%K vs
%K Te
%K dichalcogenide electrophile
%K Extended Chalcogenorhodamine Dyes Extended rhodamines
%X Extended
rhodamines were prepared by inserting an additional fused benzene
ring into the rhodamine xanthylium core. The synthesis of “bent”
dyes 4-E (E = S, Se, Te) began with regioselective lithiation
of the 1-position of N,N-diisopropyl
6-dimethylamino-2-naphthamide (11b) with n-BuLi/TMEDA (≥25:1 1- vs 3-lithiation) followed by addition
of a dichalcogenide electrophile. The synthesis of “linear”
dyes 5-E (E = S, Se, Te) began with regioselective lithiation
of the 3-position of N,N-diethyl
6-dimethylamino-2-naphthamide (11a) with lithium tetramethylpiperidide
(≥50:1 3- vs 1-lithiation) followed by addition of a dichalcogenide
electrophile. Dyes 4-E and 5-E have absorption
maxima in the 633–700 nm range. Dyes 4-E generate
singlet oxygen upon irradiation while dyes 4-S and 5-S are highly fluorescent, with quantum yields for fluorescence
of 0.47 and 0.18, respectively. DFT calculations were performed on
the 4-E and 5-E chromophores. For the dyes 4-E, the lowest energy excitation is due solely to the HOMO–LUMO
transition. For dyes 5-E, the lowest energy excitation
is a combination of two excitations, both having contributions from
the HOMO to LUMO and HOMO-1 to LUMO.
%I ACS Publications