# Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones

## TL;DR

This paper reports the synthesis and properties of new 1,3-tropolone compounds with ionochromic and cytotoxic effects.

## Contribution

The study introduces new 2-(indolin-2-yl)-1,3-tropolones with dual ion-sensing and anticancer potential.

## Key findings

- The compounds show emission switching in response to CN− and Hg2+ ions.
- One compound shows high cytotoxic activity against A431 and H1299 cancer cell lines.
- X-ray analysis confirmed the structure of a specific tropolone derivative.

## Abstract

The acid-catalyzed reaction of benzo[e(g)] derivatives of 2,3,3-trimethylindolenines with o-chloranil leads to new 2-(benzo[e(g)]indolin-2-yl)-5,6,7-trichloro-1,3-tropolones and 2-(benzo[e(g)]indolin-2-yl)-4,5,6,7-tetrachloro-1,3-tropolones. Based on the results of PBE0/6-311+G(d,p) calculations, the structural and energetic characteristics of the tautomeric forms of the obtained 1,3-tropolones were determined. The structure of 2-(3,3-dimethyl-3H-benzo[g]indolin-2-yl)-5,6,7-trichloro-1,3-tropolone was determined by X-ray diffraction analysis. The compounds obtained are capable of switching emission at 420–440 nm and 476–530 nm upon successive exposure to CN− and Hg2+ ions in an acetonitrile solution. 2-(1,1-Dimethyl-1H-benzo[e]indolin-2-yl)-5,6,7-trichloro-1,3-tropolone exhibited high in vitro cytotoxic activity against A431 skin cancer and H1299 lung cancer cell lines.