Systematic investigation of phthalocyanines, naphthalocyanines, and their aza-analogues. Effect of the isosteric aza-replacement in the core

Abstract

A series of zinc complexes of phthalocyanine, naphthalocyanine and their aza-analogues with alkylsulfanyl substituents was synthesized and characterized by UV-vis and MCD spectroscopy, and their redox properties were investigated using CV, DPV, and SWV approaches as well as spectroelectrochemical methods. Aggregation, photostability, singlet oxygen production, and fluorescence quantum yields of the target complexes were studied as a function of the stepwise substitution of the aromatic C-H fragments by nitrogen atoms. The electronic structure and vertical excitation energies of the target compounds were probed by DFT-PCM and TDDFT-PCM approaches. Introduction of additional nitrogens into the structure leads to a hypsochromic shift of the Q-band and makes the macrocycle strongly electron deficient and more photostable. The impact on the photophysics is limited. The relationships between the type of macrocycle and the studied properties were defined.

Tetra(pyrazino[2,3-b]pyrazino)porphyrazines: Synthesis, absorption, photophysical and electrochemical properties of strongly electron-deficient macrocycles

“…Trace amounts of the products with Q-band absorption at expected wavelengths were observed for 6c, 6d and 6f and not for 6e. Interestingly, intensively green colored solutions were obtained for reaction of 4a and 4b that allowed successful isolation of 6a (this compound has been reported by us recently [9]) and 6b in reasonable yields about 50%. The reaction can be performed both in pyridine or DMF with comparable yields.…”

“…Comparison can be made also with their analogous compounds with different rings fused to the porphyrazine core. Thus, presence of additional nitrogens in TPyzPyzPzs induced approximately 50 nm (for tert-butylsulfanyls substituted macrocycles [9]) or 20 nm (for pyridyl substituted macrocycles [18]) blue shift when compared with tetra(6,7-quinoxalino) porphyrazines. Absorption spectra of TPyzPyzPzs 6a and 6b were collected also in THF where they also did not exert any aggregation (Figs.…”

“…Pyridine was selected for monitoring the absorption spectra due to its known suppressing effect on the aggregation. Aggregation is typically more expressed at enlarged macrocycles [9] and in particular at those with not very bulky peripheraly substituents (e.g. 6d-6f).…”

“…Mørkved et al reported only decomposition of starting mono-or dihetaryl substituted pyrazino [2,3-b]pyrazine-2,3-dicarbonitriles under both Linstead type or template supported methods [7,8]. For this reason, only two papers in peer-reviewed journals [9,10] and one patent [11] can be found to have reported on successful TPyzPyzPzs synthesis.…”

Photophysical and Photochemical Properties and Aggregation Behavior of Phthalocyanine and Naphthalocyanine Derivatives

“…1,2 Both macrocycles are widely applied as industrial dyes, in solar cells, 3 nonlinear optics, 4 electrochromic devices, 5 photodynamic therapy (PDT) 6 and chemical sensors. Phthalocyanines (Pc) and naphtalocyanines have a high tendency to aggregate, especially in aqueous solution.…”