Figure 5 Simulated Absorption Spectrum of Heterocyclic and
Amino-ethyl-amino Modified Dyes Obtained by ωB97XD/6-311G(d,p)
Calculation in Dichloromethane
The MTPADP-Pyc molecule is a conjugate, so its maximum absorption peak
position undergoes a significant red shift, and a new absorption peak
appears, extending the absorption spectrum towards 800 nm. In the
absorption spectrum of MTPAQL-Pyc molecule, a new absorption peak
appeared near the maximum absorption peak, and the absorption intensity
was higher than the maximum absorption peak, broadening the entire
absorption spectrum, and the maximum absorption peak was red-shifted.
The HOMO and LUMO of the MTPABD-Pyc molecule overlap to a greater
extent, exhibiting the hyper-conjugation of the entire molecule, and
thus its absorption spectrum has a significant red shift. The absorption
spectrum of MTPAPA-Pyc molecule is similar to that of MTPABT-Pyc
molecule in shape, but the maximum absorption peak is red-shifted and
the absorption band is slightly wider. In summary, the absorption
spectra of MTPADP-Pyc, MTPAQL-Pyc, and MTPABD-Pyc molecules all showed a
new absorption peak near the maximum absorption peak, which broadened
the absorption spectrum to some extent and improved the absorption
characteristics of dye molecules.
After the introduction of amino-ethyl-amino group, the intensity of the
maximum absorption peak of all dyes is lower than that of MTPA-Pyc,
which will affect the light absorption efficiency of such dyes at the
maximum absorption wavelength. However, the maximum absorption peaks of
MTPADP-APyc, MTPAQL-APyc, MTPABD-APyc and MTPAPA-APyc molecules are
significantly red-shifted compared with that of MTPA-Pyc.