Decomposition of solid C60-indene adducts by retro Diels Alder reaction-A kinetic and thermodynamic study

• Type: Article in International Scientific Journal
• Date: 2023

Authors

Rodrigues, DJL (Author) Other; Pina, IBOM (Author) Other; Luis M N B F Santos (Author) FCUP; Lima, CFRAC (Author) FCUP

Journal

Title: Diamond and Related Materials

Vol. 136

ISSN: 0925-9635

Publisher: Elsevier

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Other information

Authenticus ID: P-00Y-GHZ

DOI: 10.1016/j.diamond.2023.110031

Abstract (EN): Diels-Alder cycloaddition is a common synthetic approach to functionalize fullerenes. However, the stability of such fullerene adducts is hampered by the existence of the Retro Diels-Alder (RDA) reaction. Herein, the RDA reactions in the solid phase of the mono and bisadducts of C60 with indene, IC60MA and IC60BA, were studied by differential scanning calorimetry and thermogravimetric analysis. The RDA reaction in solid IC60MA occurs at a higher temperature than in IC60BA. IC60MA decomposition follows a first-order rate law and in IC60BA it is described by two consecutive first-order reaction steps. The decomposition of both adducts yields a metastable C60 solid. The higher decomposition temperature of IC60MA is due to higher activation energy, Ea, and lower preexponential factor, A. The values of Ea for the RDA reactions differ due to crystal packing efficiency in the solids. The measured A values were found to reflect the statistical weight of C60-Indene bonds that can be broken. A reaction mechanism was proposed for the decomposition of the fullerene adducts. The enthalpies of sublimation of IC60MA and IC60BA were estimated based on the enthalpies of their respective RDA reactions. Additionally, the heat capacities of the solid fullerenes (C60, IC60MA, and IC60BA), at T = 298.15 K, were measured by highprecision heat capacity drop calorimetry, indicating that the rotational motion of C60 in the crystal increases its expected heat capacity.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10