title: Dimers of polar chromophores in solution: role of excitonic interactions in one- and two-photon absorption properties.
abstract: The possibility to exploit a bottom-up approach to design and synthesize multichromophoric structures from a single molecular unit is strategic for the targeted synthesis of molecular compounds with well defined linear and nonlinear absorption properties. In this view, it is important to be able to predict the properties of multichromophoric units, based on the knowledge of the properties of the individual chromophores and their mutual arrangement. To this end, we present a combined experimental and theoretical study on 4-(para-di-n-butylaminostyryl)-pyridine, a push-pull molecule, and its dimer, 4,4'-bis(para-di-n-butylaminostyryl)-2,2'-bipyridine, formed by connecting the two pyridine groups into a bipyridine structure. One photon absorption and fluorescence spectra are measured in solvents of different polarity, and two-photon absorption spectra are recorded in dichloromethane. Experimental results are compared with results of TDDFT (Time-Dependent Density Functional Theory) and CIS (Configuration Interaction with Single excitation) methods implemented in the Gaussian03 program suite. An essential-state analysis of optical spectra is used to rationalize the observed behavior.
authors.affiliation: Dipartimento di Scienze Chimiche e UdR INSTM Padova, Università di Padova, Padova, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Todescato
authors.forename: I
authors.initials: I
authors.lastname: Fortunati
authors.forename: S
authors.initials: S
authors.lastname: Carlotto
authors.forename: C
authors.initials: C
authors.lastname: Ferrante
authors.forename: L
authors.initials: L
authors.lastname: Grisanti
authors.forename: C
authors.initials: C
authors.lastname: Sissa
authors.forename: A
authors.initials: A
authors.lastname: Painelli
authors.forename: A
authors.initials: A
authors.lastname: Colombo
authors.forename: C
authors.initials: C
authors.lastname: Dragonetti
authors.forename: D
authors.initials: D
authors.lastname: Roberto
mesh_terms: D015082:2,2'-Dipyridyl / Q000031:analogs & derivatives* / Q000737:chemistry*; D000042:Absorption; D019281:Dimerization; D008962:Models, Theoretical; D017785:Photons; D011725:Pyridines / Q000737:chemistry*; D011789:Quantum Theory; D012996:Solutions / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: C561177:4,4'-bis(para-di-n-butylaminostyryl)-2,2'-bipyridine; C561176:4-(para-di-n-butylaminostyryl)-pyridine; D011725:Pyridines; D012996:Solutions; D015082:2,2'-Dipyridyl