Phthalocyanine Analogues: Unexpectedly Facile Access to Non‐Peripherally Substituted Octaalkyl Tetrabenzotriazaporphyrins, Tetrabenzodiazaporphyrins, Tetrabenzomonoazaporphyrins and Tetrabenzoporphyrins

Abstract

Controlled syntheses of phthalocyanine/benzoporphyrin hybrid structures have been achieved. We report a simple means for obtaining non-peripherally octaalkyl-substituted derivatives of tetrabenzotriazaporphyrin (TBTAP), tetrabenzodiazaporphyrin (TBDAP), tetrabenzomonoazaporphyrin (TBMAP) and tetrabenzoporphyrin (TBP) macrocycles by treating 3,6-dialkyl phthalonitriles with differing amounts of the Grignard reagent MeMgBr. This range of macrocyclic products is not obtained from corresponding reactions of a Grignard reagent with 4-substituted phthalonitriles, reported previously, or reaction of MeMgBr with a 4,5-dialkyl phthalonitrile. Attempts to form a meso-substituted TBTAP from 3,6-dialkyl phthalonitriles by reaction with benzyl and long-chain alkyl Grignard reagents unexpectedly gave only the parent macrocycle unsubstituted at the meso position. The synthetic protocols are by far the most straightforward and convenient means to access these interesting, but scarcely studied, classes of material. The new series of substituted macrocyclic compounds, obtained as the metal-free and magnesium- and copper(II)-metallated derivatives, show trends in the UV/Vis spectra consistent with those predicted elsewhere by Kobayashi. Characterisation of the new families allows further trends to be identified as meso-nitrogen atoms are sequentially replaced by methine bridges, for example, the compounds provide novel examples of macrocyclic structures that show columnar mesophase behaviour. Single-crystal X-ray structure determinations have been obtained for three magnesium-metallated derivatives bearing eight hexyl substituents and constitute the first set of structural data obtained for such a series.

First examples of functionalisation of meso -aryl tetrabenzotriazaporphyrins (TBTAPs) through cross-coupling reactions

“…Our group has recently reported a new procedure for the controlled synthesis of TBTAP hybrids, 5 and a complementary approach to the transtetrabenzodiazaporphyrins (trans-TBDAPs) has separately been developed by Ceprakov and coworkers. 6 Alongside the new syntheses we have refined and improved the Grignard reagent initiated macrocyclisation approach, delivering the full range of hybrids in specific cases, 7 and most recently reporting the series of isomeric meso-(bromophenyl)TBTAPs. 8 The latter series were targeted as particularly useful intermediates for further functionalisation, and this paper describes the first successful extensions of this chemistry through cross-coupling reactions.…”

Tetrabenzodiazaporphyrin: the semiconducting hybrid of phthalocyanine and tetrabenzoporphyrin

“…Diazaporphyrins have been also prepared by the reaction of dibromodipyrromethene with sodium azide [23,24]. However, TBDAPs were isolated from a mixture of mono-, di-, triazaporphyrins and Pc which were obtained by reaction of phthalonitrile or its derivatives [25][26][27][28][29] since isoindole was too unstable to prepare dibromodi(isoindol-1-yl)methene. Our methodology by the retro Diels-Alder conversion of the bicyclo[2.2.2]octadiene(BCOD)-fused precursors is suitable for the selective synthesis of TBDAPs.…”

Characterization, liquid crystallinity and spin-coated films of some metalated 1,4,8,11,15,18,22,25-octaalkyl tetrabenzo [b,g,l,q][5,10,15]triazaporphyrin derivatives

“…Subsequently, we re-prepared 1 and reported the first formation of the metal-free octadecyl analog 2 from the appropriate 3,6-dialkylphthalonitriles and MeMgBr. Both were converted into their copper metalated derivatives [23], preliminary findings for which indicated they also exhibited columnar mesophase behavior.…”