Carbazolopyridinophanes (CP) with internal hydrogen bonds can act as “turn-on” sensors for hydrogen-bond disrupting species where the detection limit depends on background fluorescence intensity. In the optimum geometry of the carbazole-pyridine complex, the rings are perpendicular and the N-H<sup>…</sup>N distance is 2.01 Å. For CP with three-atom C-S-C bridges, the bridges are too short to allow this, imposing a 50-degree twist and an internal hydrogen-bond distance of 1.80 Å. The current study describes synthesis of a carbazolopyridinophane with four-atom all-carbon bridges, which should allow a geometry with an internal hydrogen-bond length and carbazole-pyridine twist angle closer to the optimum values, leading to less background fluorescence. Theoretical studies compare the twist angles and N-H<sup>…</sup>N distances of carbazolopyridinophanes with three-, four-, and five-carbon bridges.

Effect of bridge length on sensing behavior of carbazolopyridinophanes

2019 Spring National Meeting

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