Acid-base properties of tetrapyrazinoporphyrazines. 1. Deprotonation of octaethyltetrapyrazinoporphyrazine in CH 2 Cl 2 , THF, DMSO and pyridine. The crucial role of water

Titanium‐Based Tetrakis‐2,3‐[5,6‐di(Substituted)pyrazino]porphyrazine: Synthesis and Characterization

“…The voltammogram of ligand 2a in DMSO shows only one reversible peak at -0.77 V (Figure 3), probably due to the reduction of dianion 2a 2-. This result is in agreement with the literature [18,19,25] where tetrapyrazinoporphyrazines are known to undergo deprotonation upon dissolution in DMSO and their dianion TPysPzs 2are in equilibrium with the neutral forms TPysPzsH 2 . In contrast, the CV of 2a in DMF/CH 2 Cl 2 , 5:1 shows one irreversible peak at -0.89 V for the reduction of the corresponding dianion and a second reversible peak, barely visible, at -1.42 V, which can be probably attributed to the reduction of its neutral form (Figure 3).…”

Phthalocyanines and Tetrapyrazinoporphyrazines with Two Cationic Donuts: High Photodynamic Activity as a Result of Rigid Spatial Arrangement of Peripheral Substituents

“…As briefly mentioned above, metal-free ligands 7 , 9 , 12 , and 15 exhibited atypical behavior in that they were deprotonated at the acidic central NH . The Q bands of 7 and 12 remained typically split due to the reduced D 2 h symmetry (Supporting Information, Figure S20) in nonbasic organic solvents (THF and CHCl 3 ).…”

“…As briefly mentioned above, metal-free ligands 7, 9, 12, and 15 exhibited atypical behavior in that they were deprotonated at the acidic central NH. 26 The Q bands of 7 and 12 remained typically split due to the reduced D 2h symmetry (Supporting Information, Figure S20) in nonbasic organic solvents (THF and CHCl 3 ). However, the deprotonation of the central NH in DMF or pyridine restored (sometimes only partially) the D 4h symmetry of the macrocycle, and the Q band was found to be single and unsplit.…”

Amphiprotism-Coupled Near-Infrared Emission in Extended Pyrazinacenes Containing Seven Linearly Fused Pyrazine Units

“…Compound 1 has a calculated DPE of 311.3 kcal/mol similar to that of the highly nitrogenated, electron deficient tetrapyrazinoporphyrazine (316.1 kcal/mol), which readily deprotonates upon dissolution in DMSO. 13 To effect further deprotonation, the use of a large excess of hydroxide or more strongly basic lithium bis(trimethylsilyl)amide is necessary and results in the formation of the doubly deprotonated species with a λ max = 741 nm in THF (compound 1, see Figure S17). The difficult second deprotonation of 1 is consistent with its high calculated DPE of 743.8 kcal/mol.…”

“…The gas-phase deprotonation enthalpy (DPE) was calculated using the semiempirical AM1 method as implemented in the Spartan ’14 program (see Supporting Information). Compound 1 has a calculated DPE of 311.3 kcal/mol similar to that of the highly nitrogenated, electron-deficient tetrapyrazino­porphyrazine (316.1 kcal/mol), which readily deprotonates upon dissolution in DMSO . To effect further deprotonation, the use of a large excess of hydroxide or more strongly basic lithium bis­(trimethylsilyl)­amide is necessary and results in the formation of the doubly deprotonated species with a λ max = 741 nm in THF (compound 1 ; see Figure S17).…”