title: Modeling emission features of salicylidene aniline molecular crystals: A QM/QM' approach.
abstract: A new computational protocol relying on the use of electrostatic embedding, derived from QM/QM' ONIOM calculations, to simulate the effect of the crystalline environment on the emission spectra of molecular crystals is here applied to the β-form of salicylidene aniline (SA). The first singlet excited states (S1 ) of the SA cis-keto and trans-keto conformers, surrounded by a cluster of other molecules representing the crystalline structure, were optimized by using a QM/QM' ONIOM approach with and without electronic embedding. The model system consisting of the central salicylidene aniline molecule was treated at the DFT level by using either the B3LYP, PBE0, or the CAM-B3LYP functional, whereas the real system was treated at the HF level. The CAM-B3LYP/HF level of theory provides emission energies in good agreement with experiment with differences of -20/-32 nm (cis-keto form) and -8/-14 nm (trans-keto form), respectively, whereas notably larger differences are obtained using global hybrids. Though such differences on the optical properties arise from the density functional choice, the contribution of the electronic embedding is rather independent of the functional used. This plays in favor of a more general applicability of the present protocol to other crystalline molecular systems.
authors.affiliation: Dipartimento Di Scienze Chimiche e Geologiche, Università di Modena e Reggio-Emilia, via G. Campi 103, Modena, I-41125, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Presti
authors.affiliation: Institut de Recherche de Chimie Paris, CNRS Chimie ParisTech, 11 Rue P. et M. Curie, F-75005, Paris, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Labat
authors.affiliation: Dipartimento Di Scienze Chimiche e Geologiche, Università di Modena e Reggio-Emilia, via G. Campi 103, Modena, I-41125, Italy.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Pedone
authors.affiliation: Gaussian Inc., 340 Quinnipiac Str., Bldg. 40, Wallingford, Connecticut, 06492.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Frisch
authors.affiliation: Chemistry and Chemical Biology, University of California, Merced, California, 95343.
authors.forename: Hrant P
authors.initials: HP
authors.lastname: Hratchian
authors.affiliation: Institut de Recherche de Chimie Paris, CNRS Chimie ParisTech, 11 Rue P. et M. Curie, F-75005, Paris, France.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Ciofini
authors.affiliation: Dipartimento Di Scienze Chimiche e Geologiche, Università di Modena e Reggio-Emilia, via G. Campi 103, Modena, I-41125, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Cristina Menziani
authors.affiliation: Institut de Recherche de Chimie Paris, CNRS Chimie ParisTech, 11 Rue P. et M. Curie, F-75005, Paris, France.|Institut Universitaire de France, 103 Boulevard Saint Michel, Paris, F-75005, France.
authors.forename: Carlo
authors.initials: C
authors.lastname: Adamo
keywords: DFT; ONIOM QM/QM’; TD-DFT; molecular crystals; photophysics