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Two close structurally related isomers of nonaromatic meso‐fused dicarbahexaphyrins were synthesized by condensing one equivalent of fluorene based tripyrrane with one equivalent of pentafluorobenzaldehyde in CH2Cl2 under BF3.OEt2 catalyzed conditions. The cis and trans isomers of meso‐fused dicarbahexaphyrins were separated by preparative thin‐layer chromatography and isolated pure macrocycles as green solids in 6–7% yields. NMR spectra of cis and trans isomers are quite distinct from each other and trans isomer was very symmetric and showed fewer resonances than cis isomer in NMR. The NMR study supported the nonaromatic nature of both cis and trans isomers of meso‐fused dicarbahexaphyrins. DFT optimized structures revealed that the cis isomer adopted a singly twisted puckered conformation whereas the trans isomer displayed a saddle like conformation. Both cis and trans isomers almost showed similar nonaromatic absorption features with slight differences in their peak maxima. However, the protonated derivative of cis isomer showed absorption bands in visible‐NIR region with bands extended upto 1000 nm whereas the trans isomer showed strong bands in the visible region. Both cis and trans macrocycles were easier to oxidize and reduce and TD‐DFT studies corroborated with the experimental findings.

Diethyl chlorophosphate (DCP), an organophosphate, is utilized as a pesticide, herbicide, and for various other applications. Despite many uses of organophosphates, the organophosphates are noxious and harmful substances, and their selective detection is a critical concern in the context of the environment, physiology, and social security. In a methodological quest, here we have synthesized two Schiff base compounds 1 and 2 by introducing the hydroxyl group at the α-position of 3-pyrrolyl BODIPY either directly as hydroxylamine 1 or at the ortho position of aryl ring as 2-aminophenol 2. Both compounds 1 and 2 exhibited high selectivity and high sensitivity for DCP over other pesticides in the aqueous-alcoholic medium at physiological pH. This occurs via nucleophilic phosphorylation of the hydroxyl group, which resulted in both compounds exhibiting two different optical signals following the structurefunction correlation of the pyrrolyl BODIPY systems. Upon binding DCP, compound 1 showed a quenching in the optical spectrum because of phosphorylation of hydroxyl group whereas compound 2 exhibited enhancements in both absorption and fluorescence spectra because of hydroxyl phosphorylation followed by intramolecular cyclization. Furthermore, the fluorescent microscopy experiments also indicated that the compound could be used as a fluorescent compound for sensing DCP in plant tissues.

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