Dipyreno- and diperyleno-anthracenes from glyoxylic Perkin reactions

Abstract

Twofold Perkin condensation of 2,5-dibromophenylene-1,4-diacetic acid with arylglyoxylic acids followed by cyclo-dehydrobromination leads to dipyreno- and diperyleno-anthracene tetraesters and diimides. The imides show surprisingly large absorption shifts versus the esters, illustrating that electron-withdrawing substituents at the anthracene unit efficiently impart long wavelength absorption in such electron-deficient graphene nanoribbon fragments.

From Chrysene to Double [5]Helicenes

“…This shows that whereas the chrysenylene-dianion is more stable once formed due to the twofold sextet stabilization, its formation requires harsher conditions due to the shorter distance between the two substitution positions. The mono-and diglyoxylic acids 3 and 6 were subjected to double Perkin condensations with 2,5-dibromophenylene-1,4-diacetic acid 7 [1] and 2-bromophenylacetic acid 8, respectively, followed by same-pot fourfold esterification with excess alkanol and 1-bromoalkane in the presence of 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) to yield dibromo phenylene-bis(chrysenylmaleic) tetrabutyl ester 9 and chrysenylene-bis(bromophenylmaleic) tetrapropyl ester 10, respectively, in 69 and 71 % yield ( Figure 1). These highly congested yet conformationally flexible bismaleates show, as usual, [1,5,6] extremely broadened proton NMR spectra due to slow rotations on the measurement timescale.…”

“…The ability of alkylimide groups to render planar arenes soluble is nevertheless limited by the size of the arene for a given number of substituents, as we experienced recently with a diperyleno-anthracene bearing two long α-branched alkylimide groups, which is soluble only on heating in chlorinated solvents. [1] The strong coplanar aggregation of large arenes may be reduced by the introduction of a bend or twist, as is illustrated by the far superior solubilities of helicenes compared with their planar phenacene isomers. [2] Even slight deviations from planarity such as induced by a [4]helicene fragment may give rise to good solubilities and to hindered crystallization rearrangement of the conjugated carbon skeleton is identified as side reaction.…”

Columnar Liquid‐Crystalline Dinaphthoperylenetetracarboxdiimides

“…CV and DPV were performed in a three electrode cell, utilizing an Autolab PGStat20 potentiostat, driven by GPES software (General Purpose Electrochemical System, Version 4.4, EcoChemie B.V., Utrecht, The Netherlands), a platinum wire counter electrode, a 1.6 mm platinum disc working electrode, and a non-aqueous reference electrode comprised of a silver wire in a 0.01 m solution of AgNO 3 and 0.1 m tetrabutylammonium perchlorate in acetonitrile; the analytes were dissolved in CH 2 Cl 2 supplemented with 0.1 m tetrabutylammonium hexafluorophosphate and degassed by bubbling argon prior to measurement. Diethyl perylenylene-3,9-diglyoxylate (15): A solution of ethyl perylenyl-3-glyoxylate [2] (21.1 g, 352.4 g mol À1 , 60 mmol) and ethyl chloroglyoxylate (20.5 g, 136.5 g mol À1 , 150 mmol) in CH 2 Cl 2 (500 mL) was added to a stirred slurry of aluminium trichloride (40 g, 133.3 g mol À1 , 300 mmol) in CH 2 Cl 2 (500 mL) in a 1 L flask. The green mixture was stirred at room temperature under exclusion of moisture for 64 h and then poured into a stirred mixture of ice and 5 % aqueous hydrochloric acid (500 mL).…”

“…As we have shown recently, this cyclization can be achieved either by palladium-catalyzed dehydrobromination, [2][3][4] which necessitates an ortho-positioned bromo substituent in either the arylacetic or the arylglyoxylic acid, or by oxidative photocyclization, [5] which does not necessitate additional functional groups in the precursor acids. If either one of the two precursors is a diacid, double Perkin condensations and cyclizations may yield tetracarboxylic tetraesters or diimides, which may be of interest as charge-transporting dyes for organic electronics, in analogy to the widely used perylene-3,4:9,10-tetracarboxdiimides (PTCDIs).…”

“…[2][3][4] The inverse approach, the condensation of an arylenediglyoxylic acid with 2-bromophenylacetic acid to yield dinaphthoarenetetracarboxylic acid derivatives, is hampered by the fact that the direct acylation of unsubstituted polycylic arenes such as pyrene or perylene with excess ClCOCO 2 Et gives much more selectively the monoacylation product than with conventional acid chlorides, such as AcCl or BzCl, which are known to easily give diacylation, albeit often as mixture of regioisomers. [8] This can be attributed to the considerably more deactivating effect of a -COCO 2 R substituent on further acylation compared to -COR.…”