Physicochemical Characterization of Subporphyrazines—Lower Subphthalocyanine Homologues

Abstract

Physicochemical characterization of boron(III) subporphyrazines (SubPzs)--lower subphthalocyanine (SubPc) homologues--has been carried out for the first time. The SubPz macrocycle can act both as an oxidizing and a reducing entity, giving rise to stable radical anion or radical cation species, respectively. SubPzs are luminescent and exhibit fluorescence quantum yields that are in the range known for SubPcs. The peripheral substitution plays a dramatic role with respect to the luminescence properties. Moreover, as with SubPcs, deactivation of the singlet excited state of the SubPzs by intersystem crossing affords long-lived triplet excited states, which are amenable to being used as singlet-oxygen generators. Subporphyrazines are also promising electro- and photoactive materials for molecular photovoltaics.

1,3-Dithiole-2-one-Fused Subphthalocyanine and Subporphyrazine: Synthesis and Properties Arising from the 1,3-Dithiole-2-one Units

“…Similar quenching observed for the S-alkyl-substituted SubPz was explained by Torres et al in terms of the intersystem crossing from the singlet excited state to the triplet state. 20 To gain detailed insight into the electronic structures of S 2 CO compounds, MCD spectroscopy measurements and time-dependent density functional theory (TDDFT) calculations were performed. MCD spectroscopy can provide information about the degeneracy of frontier orbitals based on characteristic MCD signal patterns known as a Faraday A term for the degenerate transition and B terms for magnetically coupled nondegenerate transitions.…”

“…Unlike regular SubPz, S 2 CO-fused compounds were virtually nonfluorescent due to the heavy atom effect, whereas S 2 CO-SubPc 2b exhibits intense fluorescence at 594 nm with a fluorescence quantum yield of 15% (Figure S14). Similar quenching observed for the S -alkyl-substituted SubPz was explained by Torres et al in terms of the intersystem crossing from the singlet excited state to the triplet state …”

Photochemical Behavior of Beryllium Complexes with Subporphyrazines and Subphthalocyanines

“…43 Although BeSubPz and BeSubPc in which the axial ligand A is a water molecule are found to be stable, in the present study we decided to use F − and Cl − for the sake of maintaining a maximum similarity with the boron-containing analogues previously reported in the literature. 14,15 Structure of BeSubPc(A,R) and BeSubPz(A,R) Complexes. The first set of selected BeSubPc(A,R) and BeSubPz(A,R) complexes under study are represented in Figure 1, in which A is the atom in the axial position (A = F − , Cl − ) located at the top of the structure and R are the peripheral substituents of the BeSubPc and BeSubPz units.…”

Ruthenoarenes versus Phenol Derivatives as Axial Linkers for Subporphyrazine Dimers and Trimers

“…To gain a greater insight into the determinants of the aforementioned trend, the compounds of this study were analyzed by using transient absorption spectroscopy. Upon excitation with 387 and/or 490 nm light, the phenoxy‐SubPz 6 and its corresponding Ru II complex 7 , were found to display singlet excited state characteristics that are typical of those observed for hydroxysubporphyrazines (see the Supporting Information, Figures S‐33 and S‐34) 25. In particular, a broad absorption with a maximum at 680 nm is seen.…”

“…Upon excitation with 387 and/or 490 nm light, the phenoxy-SubPz 6 and its corresponding Ru II complex 7, were found to display singlet excited state characteristics that are typical of those observed for hydroxysubporphyrazines (see the Supporting Information, Figures S-33 and S-34). [25] In particular, a broad absorption with a maximum at 680 nm is seen. This feature is accompanied by ground state bleaching at 500 nm.…”