title: Metal Dependence on the Bidirectionality and Reversibility of the Singlet Energy Transfer in Artificial Special Pair-Containing Dyads.
abstract: The demetalation of a precursor dyad, 3, built upon a zinc(II)-containing artificial special pair and free-base antenna, leads to a new dyad, 4, for singlet energy transfer composed of cofacial free-base porphyrins (acceptor), [Fb]2bridged by a 1,4-C6H4group to a free-base antenna (donor), [Fb]. This dyad exhibits the general structure [M]2-C6H4-[Fb], where [M]2= [Fb]2, and completes a series reported earlier, where [M]2= [Mg]2(2) and [Zn]2(3). The latter dyads exhibit a bidirectional energy-transfer process at 298 K for 2 and at 77 K for 3. Interestingly, a very scarce case of cycling process is observed for the zinc-containing dyad at 298 K. The newly reported compound 4 exhibits a quasi unidirectional process [Fb]*→[Fb]2(major, kET= 2 × 1011s-1at 298 K), where the remaining is [Fb]2*→[Fb] (minor, kET= 8 × 109s-1at 298 K), thus completing all possibilities. The results are analyzed in terms of molecular orbital couplings (density functional theory computations), Förster resonance energy transfer parameters, and temperature dependence of the decay traces. This study brings major insights about artificial special pair-containing dyads and clearly contributes to a better understanding of the communication between the two main components of our models and those already described in the literature.
authors.affiliation: Département de Chimie, Université de Sherbrooke , Sherbrooke J1K 2R1, PQ, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Langlois
authors.affiliation: Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR CNRS 6302, Univ. Bourgogne Franche-Comté , 9 Avenue Alain Savary, BP 47870-21078 Dijon, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Camus
authors.affiliation: Département de Chimie, Université de Sherbrooke , Sherbrooke J1K 2R1, PQ, Canada.
authors.forename: Paul-Ludovic
authors.initials: PL
authors.lastname: Karsenti
authors.affiliation: Institut de Chimie Moléculaire de l'Université de Bourgogne, UMR CNRS 6302, Univ. Bourgogne Franche-Comté , 9 Avenue Alain Savary, BP 47870-21078 Dijon, France.
authors.forename: Roger
authors.identifier: http://orcid.org/0000-0001-7328-3695
authors.initials: R
authors.lastname: Guilard
authors.affiliation: Département de Chimie, Université de Sherbrooke , Sherbrooke J1K 2R1, PQ, Canada.
authors.forename: Pierre D
authors.initials: PD
authors.lastname: Harvey