title: A Combined Experimental-Computational Investigation to Uncover the Puzzling (Chiro-)optical Response of Pyridocyclophanes: One- and Two-Photon Spectra.
abstract: A combined experimental-computational analysis of the one- and two-photon absorption (OPA, TPA) and the electronic circular dichroism (ECD) of complex chiral shape-persistent (2,6)-pyrido[142 ]allenoacetylenic cyclophane, (P,P,P,P)-MC[142 ] enantiomers, sheds light on the origin of their peculiar spectral signatures. The study on MC[142 ], which is represented in solution by three possible conformers, indicates that two of them (chair and twist) are the prevalent conformers at room temperature; the population ratio depending on the solvent. The complex shape of the red-edge of the UV and ECD spectra is qualitatively reproduced by using vibronic calculations and assigned to progressions on the ethynyl stretchings observable only in the chair and twist conformers. The picture arising from the analysis of the linear spectra is confirmed by two-photon spectroscopies, showing that they constitute valuable tools for the exploration of high-energy electronic transitions in pyridoallenoacetylenic cyclophanes. Discrepancies among computed and experimental spectra point out that an accurate description of such complex systems with a large delocalized π framework and a dense manifold of electronic excited state remains a challenge for theoretical models.
authors.affiliation: Institute of Organic Chemistry and Biochemistry, Academy of Sciences Institution, Flemingovo nám. 2, 16610, Prague (Czech Republic).|Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Sezione di Chimica Organica, Via Moruzzi 3, 56124 Pisa (Italy).
authors.forename: Daniele
authors.initials: D
authors.lastname: Padula
authors.affiliation: Departamento de Química Orgánica, Universidade de Vigo, Lagoas-Marcosende, 36310, Vigo (Spain).
authors.forename: Inmaculada R
authors.initials: IR
authors.lastname: Lahoz
authors.affiliation: Department of Chemistry, University of Central Florida, P. O. Box 162366, Orlando, Florida 32816-2366 (USA).
authors.forename: Carlos
authors.initials: C
authors.lastname: Díaz
authors.affiliation: Department of Chemistry, University of Central Florida, P. O. Box 162366, Orlando, Florida 32816-2366 (USA).|CREOL/The College of Optics and Photonics, University of Central Florida, P. O. Box 162366, Orlando, Florida 32816-2366 (USA).
authors.forename: Florencio E
authors.initials: FE
authors.lastname: Hernández
authors.affiliation: Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Sezione di Chimica Organica, Via Moruzzi 3, 56124 Pisa (Italy).|Consiglio Nazionale delle Ricerche - CNR, Istituto di Chimica dei Composti Organo Metallici (ICCOM CNR), UOS di Pisa, Area della Ricerca, Via G. Moruzzi 1, I-56124 Pisa (Italy).
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Di Bari
authors.affiliation: Consiglio Nazionale delle Ricerche-CNR, Istituto per i Processi Chimico Fisici (IPCF-CNR), UOS di Pisa, Area della Ricerca, Via G. Moruzzi 1, 56124 Pisa (Italy).
authors.forename: Antonio
authors.initials: A
authors.lastname: Rizzo
authors.affiliation: Consiglio Nazionale delle Ricerche - CNR, Istituto di Chimica dei Composti Organo Metallici (ICCOM CNR), UOS di Pisa, Area della Ricerca, Via G. Moruzzi 1, I-56124 Pisa (Italy). fabrizio.santoro@iccom.cnr.it.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Santoro
authors.affiliation: Departamento de Química Orgánica, Universidade de Vigo, Lagoas-Marcosende, 36310, Vigo (Spain). mcid@uvigo.es.
authors.forename: M Magdalena
authors.initials: MM
authors.lastname: Cid
keywords: chirality; circular dichroism; conformation analysis; density functional calculations; quantum chemistry