Merging Triptycene, BODIPY and Porphyrin Chemistry: Synthesis and Properties of Mono‐ and Trisubstituted Triptycene Dye Arrays

Abstract

A series of functionalized triptycene scaffolds has been synthesized using 2‐formyltriptycene and 5‐(2‐triptycenyl)dipyrromethane. Using these two key precursors, mixed condensations with different aromatic aldehydes and aryl‐dipyrromethanes gave access to all members of triptycenyl meso‐substituted porphyrins (AB3‐, A2B2‐, A3B‐, and A4) and allowed their photophysical and electrochemical characterization. Additionally, the first crystal structure of tetratriptycenylporphyrin is reported. 2‐Formyltriptycene was also used for the preparation of two different mono‐BODIPY‐triptycene compounds, while 2,6,14‐triiodotriptycene was used in Suzuki and Sonogashira cross‐coupling reactions to obtain threefold BODIPY‐substituted triptycene–dye conjugates. The mono‐ and tri‐BODIPY‐substituted triptycene scaffolds exhibit good absorption in the visible to NIR region indicating the potential use of the triptycene scaffold as the core of multi‐dye light‐harvesting systems.

Current Advances in the Synthesis of Valuable Dipyrromethane Scaffolds: Classic and New Methods

“…Aiming to combine porphyrin, BODIPY and triptycene chemistry, Senge et al recently presented meso -triptycenyldipyrromethane synthon 74 , synthesized in 60% yield from the condensation of 2-formyltriptycene 73 and surplus pyrrole under standard InCl 3 -catalyzed conditions (Scheme 15) [72]. The extreme utility of dipyrromethane 74 was noticeably demonstrated by its application in the preparation of triptycene-substituted BODIPY 75a , triptycene-substituted 3-pyrrolyl-BODIPY 75b , trans -A 2 B 2 triptycenylporphyrins 76a , b and A 3 B-type triptycenylporphyrins 76c , d .…”

Towards triptycene functionalization and triptycene-linked porphyrin arrays

“…Both Suzuki and Sonogashira cross-coupling reactions were employed to realize this new class of triptycenelinked trimeric porphyrins. The three porphyrins, or three BODIPYs in 2 were either linked directly to the periphery of triptycene or via various linkers; arrays with six chromophores 3 have thus far eluded us [26,27].…”

“…While much work has been done on the functionalization of the aromatic rings of triptycene as in 2 or 3 [24][25][26][27][28][29][30], the attachment of chromophores at the bridgehead positions has yet to be realized. Functionalization of the bridgehead positions of triptycene (as in 4) allows for the attachment of moieties in a 180°F igure 1: Triptycene as a scaffold and selected porphyrin and BODIPY arrays.…”

Towards Triptycene Functionalization and Triptycene-linked Porphyrin Arrays

“…Both Suzuki and Sonogashira cross-coupling reactions were employed to realize this new class of triptycene-linked trimeric porphyrins. The three porphyrins, or three BODIPYs in 2 were either linked directly to the periphery of triptycene or via various linkers; arrays with six chromophores 3 have thus far eluded us [20,21]. While much work has been done on the functionalization of the aromatic rings of triptycene as in 2 or 3 [18][19][20][21][22][23][24], the attachment of chromophores at the bridgehead positions has yet to be realized.…”

“…The three porphyrins, or three BODIPYs in 2 were either linked directly to the periphery of triptycene or via various linkers; arrays with six chromophores 3 have thus far eluded us [20,21]. While much work has been done on the functionalization of the aromatic rings of triptycene as in 2 or 3 [18][19][20][21][22][23][24], the attachment of chromophores at the bridgehead positions has yet to be realized. Functionalization of the bridgehead positions of triptycene (as in 4) allows for the attachment of moieties in 180° linear fashion, subsequently accessing the molecular rotation observed in several other linearly substituted triptycenes [25].…”