Experimental and computational study of the energetics of methoxycoumarins

• Tipo: Artigo em Revista Científica Internacional
• Data: 2010

Autores

Victor M F Morais (Autor) ICBAS; Clara C S Sousa (Autor) FCUP; Agostinha A R Matos (Autor) FCUP

Revista

Título: Journal of Molecular Structure: THEOCHEM

Vol. 946

Páginas: 13-19

ISSN: 0166-1280

Editora: Elsevier B.V.

Indexação

ISI Web of Knowledge - 5 Citações

Scopus - 5 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-003-7CM

DOI: 10.1016/j.theochem.2009.11.036

Abstract (EN): The structure and energetics of the methoxy-derivatives of coumarin with the substituent either on the benzenic ring (5-, 6-, 7- and 8-methoxy coumarin) or on the pyrone ring (3- and 4-methoxycoumarin) is addressed on the basis of some well documented computational methods. Estimates of the enthalpies of formation are obtained using appropriate homodesmotic reactions and also atomization reactions. The condensed phase standard (p(o) = 0.1 MPa) molar enthalpy of formation for 7-methoxycoumarin was derived from the standard molar enthalpy of combustion, in oxygen, at T = 298.15 K. measured by static bomb combustion calorimetry. The standard molar enthalpy of sublimation, at T = 298.15 K, was measured by Calvet microcalorimetry. Combining these values, the enthalpy of formation in gas-phase, at T = 298.15 K. was derived: -(321.6 +/- 2.8) kJ mol(-1). The temperature of fusion, T(fusion), and fusion enthalpies, at T = T(fusion), are also reported. Good agreement between experimental and computational data is achieved. The aromaticity of these systems has been assessed through the evaluation and analysis of the Nucleus Independent Chemical Shifts (NICS) and their most significant components. NICS scan analyses have also been conducted to help clarifying the aromatic nature of the pyrone rings of these systems. (C) 2010 Published by Elsevier B.V.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 7