Non-uniformly substituted phthalocyanines and related compounds: alkylated tribenzo-imidazolo[4,5]- porphyrazines

Abstract

<jats:p> The synthesis and properties of ‘3:1’ phthalocyanines, in which three of the benzenoid rings are similarly substituted whereas the fourth is differently substituted or is replaced by a heteroaromatic ring, are overviewed with an emphasis on contributions from the group at the University of East Anglia. The synthesis of novel hepta-alkylated tribenzo-imidazolo[4,5]porphyrazines as metal-free derivatives by cross-condensation of 3,6-dialkylphthalonitrile and 1-alkyl-4,5-dicyanoimidazole is described. The compounds show Q band absorption at 701 and 660 nm. The Q band is thus hypsochromically shifted relative to the Q band absorption of the corresponding metal-free octa-alkylphthalocyanines and the metal-free hexa-alkylated derivatives of tribenzo-pyridino[3,4]porphyrazines, tribenzo-thiopheno[2,3]porphyrazines and tribenzo-thiopheno[3,4]porphyrazines. Examples of the tribenzo-imidazolo[4,5]porphyrazines have been deposited as smooth, even and transparent spin-coated films with broad-band absorption in the region 600-750 nm. </jats:p>

Phthalocyaninodehydroannulenes

“…However, on further heating to 220 8C there is an irreversible change arising from an oligomerisation process, which presumably occurs through the diyne unit in the annulene ring. A minor product of the oxidative coupling of the diethynylphthalocyanine has been identified as the cyclic trimer, a triphthalocyaninodehydro [18]annulene. Compared with the diphthalocyaninodehydro [12]annulene, the compound shows a less strongly split Q-band, and the chemical shifts of protons in proximity to the annulene ring are deshielded.…”

“…The crude product was purified by column chromatography over silica (eluent: petrol/CH 2 Cl 2 2:1) and recrystallised from cyclohexane to afford compound 8 (1.43 g, 43 % 75.75,70.40,31.81,30.57,18.70,18.66,13.07,12.98;MS (70 eV,EI): m/z (%): 350.1 (4.8), 352.1 (4.5) [M] ; IR (nujol): n Ä 2230 cm À1 (m); elemental analysis calcd (%) for C 16 H 19 N 2 O 2 Br 1 (351.24): C 54.85,H 5.47,N 8.00,Br 22.54;found C 54.71,H 5.43,N 7.89,Br 22.67. 1,11,15,18,22,phthalocyaninato nickel(ii) (3): Freshly cleaned lithium (ca. 50 mg, 7.5 mmol) was added to 3,6-didecylphthalonitrile [21] (2.56 g, 6.27 mmol) and 7 (0.30 g, 0.70 mmol) in refluxing butanol (20 mL) under argon.…”

“…Such compounds can, in principle, be prepared by several methods; [14,18] here we have utilised the cross-cyclotetramerisation approach, the reaction together of two appropriately substituted phthalonitriles. The precursors used for the synthesis of 3 and 4 are outlined in Scheme 2.…”

“…Interestingly, this spectrum showed clearly that the signals for the OCH 2 protons of 15 (d 5.12) are downfield of those of 14, (d 4.91). Matzger and Vollhardt [26] recently appraised 1 H NMR spectral data for dibenzodehydro [12]annulene and tribenzodehydro [18]annulene and ascribed the difference in chemical shifts of the ortho aromatic protons of these planar molecules to the fact that the former is paratropic (anti-aromatic), whereas the latter is diatropic (aromatic). The difference observed in the chemical shifts of the OCH 2 protons in 14 and 15 can be attributed similarly.…”

Conversion of 1,2,5-Selenadiazoloporphyrazine to Diformamidoporphyrazine

“…[10] It was reported that only its Nalkylated derivatives can react in mixed co-condensation with substituted phthalodinitriles affording low symmetry (N-alkylimidazo)tribenzoporphyrazines. [11] In present work we have made an attempt to obtain imidazo annulated porphyrazine [ Experimental UV-vis spectra were recorded using Hitachi U-2000 spectrophotometer. MALDI-TOF spectra were measured on Ultraflex Brucker Daltonics mass-spectrometer without matrix or with CCA matrix.…”