Blending Through-Space and Through-Bond π–π-Coupling in [2,2′]-Paracyclophane-oligophenylenevinylene Molecular Wires
摘要:
A series of ZnP-pCp-oPPV-C-60 conjugates covalently connected through [2,2']-paracyclophane-oligophenylenevinylene (pCp-oPPV) bridges containing one, two, and three [2,2']-paracyclophanes (pCps) has been prepared in multistep synthetic procedures involving Horner-Wadsworth-Emmons olefination reactions and/or Heck type Pd-catalyzed reactions. Molecular modeling suggests that charge transfer is effectively mediated by the pCp-oPPVs through a predominant hole-transfer mechanism. Photophysical investigation supports molecular modeling and reveals two major trends. On one hand, C-60 excitation of 1, 2, and 3 leads exclusively to charge transfer between pCp and C-60 to afford a ZnP-(pCp-oPPV)(circle+)-C-60(circle-) radical ion pair state without giving rise to a subsequent charge shift to yield the ZnP circle+-pCp-oPPV-C-60(circle-) radical ion pair state. On the other hand, ZnP excitation of 1, 2, and 3 results in a rather slow charge transfer between ZnP and C-60, after which the ZnP circle+-pCp-oPPV-C-60(circle-) radical ion pair state evolves. In temperature-dependent ZnP fluorescence experiments, which were performed in the temperature range from 273 to 338 K, two domains are discernible: low and high temperature behaviors. In the low temperature range (i.e., below 30 degrees C) the rate constants do not change, suggesting that a superexchange mechanism is the modus operandi. In the high temperature range (i.e., >30 degrees C) the rate constants increase. Moreover, we find rather strong distance dependence for 1 and 2 and weak distance dependence for 2 and 3. A damping factor of 0.145 angstrom(-1) is derived for the former pair and 0.012 angstrom(-1) for the latter.
Synthesis of planar chiral [2.2]paracyclophane-based amino thioureas and their application in asymmetric aldol reactions of ketones with isatins
作者:Yu Lu、Yudao Ma、Shaobo Yang、Manyuan Ma、Hongju Chu、Chun Song
DOI:10.1016/j.tetasy.2013.07.023
日期:2013.9
were used as bifunctionalcatalysts for organocatalytic enantioselective aldolreactions between ketones and isatins, affording the desired adducts containing a chiral tertiary alcohol in high yields (up to 92% yield) and with good enantioselectivity (up to 88% ee). This is a successful example of employing planar chiral [2.2]paracyclophane-based amino thioureas in asymmetricaldolreactions.
straightforward method for the synthesis of a new class of small organic fluorophores bearing both [2.2]paracyclophane and naphthalene subunits using an intramolecular dehydrogenative Diels–Alder reaction as a key step. These compounds are characterized by a compact three-dimensional structure as well as through-spaceconjugated push–pull systems, and possess interesting spectroscopic characteristics that may be
Highly Enantioselective Asymmetric Transfer Hydrogenation: A Practical and Scalable Method To Efficiently Access Planar Chiral [2.2]Paracyclophanes
作者:Marie-Léonie Delcourt、Simon Felder、Serge Turcaud、Corina H. Pollok、Christian Merten、Laurent Micouin、Erica Benedetti
DOI:10.1021/acs.joc.9b00372
日期:2019.5.3
(ATH) to control the planarchirality of a range of substituted [2.2]paracyclophanes (pCps). Our strategy enabled us to perform both the kinetic resolution (KR) of racemic compounds and the desymmetrization of centrosymmetric meso derivatives on synthetically useful scales. High selectivities (up to 99% ee) and good yields (up to 48% for the KRs and 74% for the desymmetrization reactions) could be observed
Planar Chiral Analogues of PRODAN Based on a [2.2]Paracyclophane Scaffold: Synthesis and Photophysical Studies
作者:Simon Felder、Marie-Léonie Delcourt、Manon H. E. Bousquet、Denis Jacquemin、Rafael Rodríguez、Ludovic Favereau、Jeanne Crassous、Laurent Micouin、Erica Benedetti
DOI:10.1021/acs.joc.1c02071
日期:2022.1.7
We describe the synthesis and photophysical characterization of differently substituted planar chiral analogues of PRODAN based on a [2.2]paracyclophane scaffold. This experimental and theoretical study highlights that the (chir)optical properties of the new “phane” compounds, which incorporate an electron-withdrawing propionyl moiety and an electron-donating dimethylamino group at their para or pseudo-para
Through-Space Charge Transfer and Nonlinear Optical Properties of Substituted Paracyclophane
作者:Joseph Zyss、Isabelle Ledoux、Sergei Volkov、Vladimir Chernyak、Shaul Mukamel、Glenn P. Bartholomew、Guillermo C. Bazan
DOI:10.1021/ja0022526
日期:2000.12.1
The introduction, within a pi -conjugated donor-acceptor molecule, of an intermediate barrier to electron tunneling and ifs size scaling and influence on,electronic polarization properties have remained so far elusive issues of great potential interest toward the fine-tuning of the linear and nonlinear optical properties of molecular materials. Paracyclophane (pCP) provides a most relevant cornerstone for more elaborate compounds where donor and acceptor substituents are made to interact through a sterically constrained pi-pi stack. A first attempt in this direction is reported here with the synthesis of a model dipolar 4-(4-dihexylaminostyryl)-16-(4-nitrostyryl)[2.2]paracyclophane and the subsequent experimental and theoretical study of its quadratic nonlinear optical properties. A major outcome of this investigation is the evidence of a significant "through-space" charge transfer as unambiguously designated by the strong departure of the beta quadratic hyperpolarizability tensor of the full doubly substituted molecule (60 x 10(-30) esu) from the additive beta value (18 x 10(-30) esu) expected for strictly noninteracting singly substituted pCP moieties, This desired increase of nonlinear efficiency upon substitution is not offset by the usual red-shift of the absorption spectrum which generally curtails application perspectives in more common uninterrupted conjugated chains. The collective nonlinear polarization behavior involving the full end-to-end molecular structure is confirmed by theoretical calculations using the Collective Electron Oscillator (CEO) approach which furthermore indicates a significantly enhanced role of electron-hole pair delocalization in the higher order nonlinear response, compared to the linear polarizability or the static dipole moment.