Solvent‐free Reactions for the Synthesis of Indolenine‐based Squaraines and Croconaines: Comparison of Thermal Heating, Mechanochemical Milling, and IR Irradiation. Issue 5 (26th January 2021)

• Record Type: Journal Article
• Authors: Zappimbulso, Nicola; Capozzi, Maria Annunziata M.; Porcheddu, Andrea; Farinola, Gianluca M.; Punzi, Angela
• Is Part Of: ChemSusChem. Volume 14:Issue 5(2021)
• Page Start: 1363
• Page End: 1369
• Publication Date: 2021-01-26
• Subjects: croconaines -- dyes -- solvent-free reactions -- squaraines -- sustainable chemistry; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.202002763
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Squaraines and croconaines are organic dyes characterized by intense absorption in the visible or near‐infrared spectral regions with applications ranging from biology to material sciences. They are commonly synthesized by condensation reactions of oxocarbonic acids (squaric or croconic acid, respectively) with electron‐rich aromatic compounds in high‐boiling organic solvents. Here, a simple, cost‐effective, and environmentally benign process was developed for the synthesis of indolenine‐based squaraines and croconaines under solvent‐free conditions. Protocols based on conventional thermal heating, mechanochemical milling, and IR‐light activation were compared. Abstract : Add some color : Squaraines and croconaines are organic dyes with intense absorptions in the visible or near‐infrared spectral regions, commonly synthesized by condensations of oxocarbonic acids with electron‐rich aromatic compounds in high‐boiling solvents. Here, a simple, cost‐effective, and environmentally benign synthesis of these dyes under solvent‐free conditions is reported, and thermal heating, mechanochemical milling, and IR‐light activation are compared as energy sources.