Photophysical Properties of New Pyrazolone Based Azo- Compounds

One- and Two-Photon Photophysical Properties, Ultrafast Dynamics, and DFT Study of Three Modified Zinc Phthalocyanines

“…In contrast, the Soret band of compound (DR1) 4 PcZn can be observed to be broadened due to the incorporation of branched chains composed of multiple groups, which can be attributed to the π–π* transition within the long branched dispersed red one (DR1) chain . Additionally, the two absorption peaks show significant blue shift compared to the other phthalocyanine samples, probably arising from a weakened π-conjugated effect with the phthalocyanine core due to the increased size of the peripheral π-conjugated branched chain and the π–π* or n−π* transitions of the azo bridge . Comparing the absorption spectra of the three compounds, the B-band and Q-band of (DR1) 4 PcZn are significantly broader than the other two Pcs, indicating the existence of a ground state interaction between the azo groups in the DR1 branches and the central phthalocyanine chromophore .…”

“…30 Additionally, the two absorption peaks show significant blue shift compared to the other phthalocyanine samples, probably arising from a weakened π-conjugated effect with the phthalocyanine core due to the increased size of the peripheral π-conjugated branched chain 31 and the π−π* or n−π* transitions of the azo bridge. 32 Comparing the absorption spectra of the three compounds, the B-band and Q-band of (DR1) 4 PcZn are significantly broader than the other two Pcs, indicating the existence of a ground state interaction between the azo groups in the DR1 branches and the central phthalocyanine chromophore. 33 Since the energy of the n → π* transition of the isolated pair of electrons of the azo molecules in the peripheral dispersed red one into the orbitals of the phthalocyanine macrocyclic ring is close to the energy of the π→π* transition, which leads to the partial overlap of the n → π* absorption band of the dispersed red one with that of the Q-band of the phthalocyanine ring, and thus a broader absorption spectrum is obtained for (DR1) 4 PcZn.…”