Jean-Michel Camus
University of Burgundy
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Featured researches published by Jean-Michel Camus.
Chemical Communications | 2011
Jean-Michel Camus; Shawkat M. Aly; Christine Stern; Roger Guilard; Pierre D. Harvey
The singlet k(ET) for cofacial β-octaalkylporphyrin/bis(meso-aryl)porphyrin dyads increases linearly with the gap between the donor-acceptor 0-0 fluorescence peaks at 77 K.
Inorganic Chemistry | 2013
Jean-Michel Camus; Shawkat M. Aly; Daniel Fortin; Roger Guilard; Pierre D. Harvey
Using a selective stepwise Suzuki cross-coupling reaction, two trimers built on three different chromophores were prepared. These trimers exhibit a D(^)A1-A2 structure where the donor D (octa-β-alkyl zinc(II)porphyrin either as diethylhexamethyl, 10a, or tetraethyltetramethyl, 10b, derivatives) through space transfers the S1 energy to two different acceptors, di(4-ethylbenzene) zinc(II)porphyrin (A1; acceptor 1) placed cofacial with D, and the corresponding free base (A2; acceptor 2), which is meso-meso-linked with A1. This structure design allows for the possibility of comparing two series of assemblies, 9a,b (D(^)A1) with 10a,b (D(^)Â1-A2), for the evaluation of the S1 energy transfer for the global process D*→A2 in the trimers. From the comparison of the decays of the fluorescence of D, the rates for through space energy transfer, kET for 10a,b (kET ≈ 6.4 × 10(9) (10a), 5.9 × 10(9) s(-1) (10b)), and those for the corresponding cofacial D(^)A1 systems, 9a,b, (kET ≈ 5.0 × 10(9) (9a), 4.7 × 10(9) s(-1) (9b)), provide an estimate for kET for the direct through space D*→A2 process (i.e., kET(D(^)A1-A2) - kET(D(^)A1) = kET(D*→A2) ∼ 1 × 10(9) s(-1)). This channel of relaxation represents ∼15% of kET for D*→A1.
Journal of Porphyrins and Phthalocyanines | 2013
Jean-Michel Camus; Adam Langlois; Shawkat M. Aly; Roger Guilard; Pierre D. Harvey
A dyad, 1, built on an artificial special pair (bis(meso-nonyl)zinc(II)porphyrin), [Zn2], a spacer (biphenylene), a bridge (1,4-benzene), and an antenna (di-meso-(3,5-di(t-butyl)phenyl)porphyrin free base), FB, is prepared by Suzuki coupling and is analyzed by absorption and steady state, and time-resolved emission spectroscopy at 298 and 77 K. Using bases from the Forster theory, evidence for two pathways for S1 energy transfer, FB* → [Zn2], and [Zn2]* → FB, along with their respective rates, kET(S1)1 and kET(S1)-1, are extracted from the comparison of the fluorescence decays monitored at the emission maximum. At 77 K, the unquenched (1.79 ([Zn2]) and 10.6 ns (FB)) and quenched components ( 10 (ns)-1), are observed, hence, demonstrating the bidirectional paths with no back energy transfer. A 298 K, only two components are detected (0.44 ([Zn2]) and 2.64 ns (FB)) and the resulting reduced τFs indicates back energy transfer, therefore cycling and equilibrium. Their global rates are 0.31 and 1.8 (ns)-1 for kET(S1)1 and kET(S1)-1 at 298 K. This large temperature dependence on kET(S1) is fully consistent with the participation of thermal activation. Finally, DFT calculations (B3LYP) were used to illustrate a clear correlation between the relative kET(S1)s and the amplitude of the MO couplings between the artificial special pair and the antenna.
Inorganic Chemistry | 2017
Adam Langlois; Jean-Michel Camus; Paul-Ludovic Karsenti; Roger Guilard; Pierre D. Harvey
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]2 bridged by a 1,4-C6H4 group 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 × 1011 s-1 at 298 K), where the remaining is [Fb]2*→[Fb] (minor, kET = 8 × 109 s-1 at 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.
European Journal of Inorganic Chemistry | 2006
Jacques Andrieu; Jean-Michel Camus; Philippe Richard; Rinaldo Poli; Luca Gonsalvi; Francesco Vizza; Maurizio Peruzzini
Inorganic Chemistry | 2002
Jacques Andrieu; Philippe Richard; Jean-Michel Camus; Rinaldo Poli
Inorganic Chemistry | 2001
Jacques Andrieu; Jean-Michel Camus; Jochen Dietz; Philippe Richard; Rinaldo Poli
European Journal of Inorganic Chemistry | 2004
Jean-Michel Camus; Jacques Andrieu; Philippe Richard; Rinaldo Poli
Tetrahedron-asymmetry | 2004
Jean-Michel Camus; Jacques Andrieu; Philippe Richard; Rinaldo Poli; Christophe Darcel; Sylvain Jugé
Inorganic Chemistry | 2003
Jean-Michel Camus; Jacques Andrieu; Rinaldo Poli; Philippe Richard; Clara Baldoli; Stefano Maiorana