The expediency of [BCMIM][Cl] ionic salt in the synthesis of tetraketones: Insights into their photophysical properties and theoretical calculations

Abstract

A simple, efficient and straightforward method for the synthesis of 2,2′-phenylmethylene-bis(3‑hydroxy-5,5-dimethyl-2-cyclohexene-1-one) derivatives has been developed. Dimedone and aldehydes underwent condensation in the presence of 6 mol% [BCMIM][Cl] ionic salt in aqueous ethanol at room temperature. A total of 20 tetraketone derivatives were successfully synthesized with high yields. The synthesized derivatives were meticulously characterized using several spectral techniques. In addition, the photophysical properties of 15 selected derivatives, such as the molar extinction coefficient (ε) and Stoke's shift (Δῡ), have been calculated. These values range from 1.2788 × 104 M−1 cm−1 to 2.1202 × 104 M−1 cm−1 and 760 cm−1 to 449 cm−1, respectively. Additionally, the experimental data is validated by density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. Investigations based on theory revealed a pattern that was consistent with the experimental results.