Asymmetric donor-acceptor molecular dyes
In one aspect, π-conjugated asymmetric molecular dyes are described herein comprising a donor (D)-acceptor (A) architecture across a thiazolothiazole electronic bridge. In some embodiments, a π-conjugated asymmetric molecular dye has a difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of at least 1.2 eV. In some embodiments, the HOMO-LUMO offset is 1.2 eV to 5 eV. The π-conjugated asymmetric molecular dye may also display a change in dipole moment between ground and excited states of at least 5 D.
1 . A π-conjugated asymmetric molecular dye of Formula I:
wherein D is an electron donor and A is an electron acceptor, the π-conjugated asymmetric molecular dye having a difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of at least 1.2 eV.
2 . The π-conjugated asymmetric molecular dye of claim 1 , wherein the difference between the HOMO and LUMO is 1.2 eV to 5 eV.
3 . The π-conjugated asymmetric molecular dye of claim 1 , wherein A comprises an aryl or heteroaryl moiety.
4 . The π-conjugated asymmetric molecular dye of claim 1 , wherein the dye is a fluorophore.
5 . The π-conjugated asymmetric molecular dye of claim 4 , wherein the dye has a solvent dependent fluorescence lifetime.
6 . The π-conjugated asymmetric molecular dye of claim 1 having a peak absorption from 400 nm to 450 nm.
7 . The π-conjugated asymmetric molecular dye of claim 1 having a peak emission from 450 nm to 650 nm.
8 . The π-conjugated asymmetric molecular dye of claim 1 wherein the dye exhibits solvatofluorochromism.
9 . The π-conjugated asymmetric molecular dye of claim 8 having a Stokes shift of 0.25 eV to 0.75 eV.
10 . The π-conjugated asymmetric molecular dye of claim 4 having a quantum yield in non-polar solvent of at least 80 percent.
11 . The π-conjugated asymmetric molecular dye of claim 1 exhibiting a change in dipole moment between ground and excited states of 12 D to 20 D.
12 . The π-conjugated asymmetric molecular dye of claim 4 , wherein fluorescence of the dye increases or decreases relative to voltage changes in a local environment of the dye.
13 . The π-conjugated asymmetric molecular dye of claim 1 , wherein the dye is amphiphilic.