Stable Inner 2H Tautomer of N-Confused-like Porphyrin Embedded with a Carbazole Subunit: Synthesis, Metal Coordination, and Magnetic and Anion Sensing Studies

Abstract

A new class of N-confused porphyrin 1 embedded with a carbazole subunit was prepared via [3 + 1] acid-catalyzed condensation of appropriate precursors. 1 underwent smooth metal complexation with Pd­(II) and Cu­(II) salts to provide the corresponding diamagnetic 1-Pd and paramagnetic 1-Cu, respectively. The single-crystal X-ray structure of 1-Pd is evident with a square-planar Pd-center through C–H activation of inverted pyrrole. Superconducting quantum interference device analysis combined with electron paramagnetic resonance (EPR) results provided insights into the paramagnetic nature of 1-Cu. Further, a ratiometric enhancement of near-IR fluorescence at 746 nm was found to be reversible upon adding CN– and F– ions. The solid-state structure of 1-Pd confirms that the anionic species is due to NH deprotonation.

Carbazole-embedded p-benziporphyrinoid: synthesis, structure and a reversible chemodosimeter for mercury(ii) ions

“…4 On the contrary, an inverted pyrrole-containing carbazole-embedded macrocycle selectively binds toxic F − and CN − ions. 20 In this work, we have modified our design strategy by incorporating a 1,4-phenylene unit embedded with a carbazole subunit for the first time. Intriguingly, such a modification resulted in a large Stokes shift and serves as a reversible turn-OFF Hg 2+ chemo-dosimeter in the visible to near-infrared (NIR) range.…”