3-(Dicyanomethylidene)indan-1-one, also named 2HIC, is a strong electron-withdrawing molecule. It can be used as electron-withdrawing acceptors to connect with donor to form acceptor–donor–acceptor (A–D–A)-type acceptor materials for the preparation of organic solar cells (OSCs).
Anhydrous sodium acetate (1.6 g, 19.5 mmol) was added to a stirred mixed solution of indane-1,3-dione (2.19 g, 14.98 mmol) and malononitrile (1.98 g, 30 mmol) in 25 mL of anhydrous ethanol at room temperature. The reaction mixture immediately showed red color and the suspended solid gradually dissolved. After 40 min of reaction, the mixture was diluted with 50 mL of water and the pH was adjusted to 1-2 by dropwise addition of concentrated hydrochloric acid. the suspension was continued to be stirred for 10 min, after which the precipitate was collected by filtration and washed with plenty of water. The crude product was purified by two recrystallizations from acetic acid to give the final 3-(dicyanomethylidene)inden-1-one in about 90% yield with a melting point of 205°C (literature value: 223-229°C).
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