The Experts below are selected from a list of 24462 Experts worldwide ranked by ideXlab platform
Toshikazu Hirao - One of the best experts on this subject based on the ideXlab platform.
-
intramolecular conformational control in Ferrocenes bearing podand dipeptide chains
Organometallics, 2001Co-Authors: Toshiyuki Moriuchi, Akihiro Nomoto, And Kazuhiro Yoshida, Toshikazu HiraoAbstract:Ferrocenes bearing podand dipeptide chains were demonstrated to induce intramolecular conformational regulation through hydrogen bondings. The single-crystal X-ray structure determination of the Ferrocene bearing the podand dipeptide chains -Gly-l-Pro-OEt confirmed the formation of two intramolecular interchain hydrogen bondings between CO (Gly) and NH (another Gly) of each podand dipeptide chain (N(1)···O(102), 2.910 A; N(101)···O(2), 2.898 A; N(201)···O(302), 2.85 A; N(301)···O(202), 2.87 A) to give a 10-membered hydrogen-bonded ring. The Ferrocene bearing the podand dipeptide chains -l-Pro-Gly-OEt is also considered to form two rigid intramolecular interchain hydrogen bondings between CO (bridging) and NH (another Gly) to give a 14-membered hydrogen-bonded ring. Such an ordered conformation was supported by the induced circular dichroism. On the other hand, the Ferrocene bearing one dipeptide chain -Gly-l-Pro-OEt is packed in a helically ordered arrangement with one turn of 15.65 A pitch height through...
-
chirality organization of Ferrocenes bearing podand dipeptide chains synthesis and structural characterization
Journal of the American Chemical Society, 2001Co-Authors: Toshiyuki Moriuchi, Akihiro Nomoto, Kazuhiro Yoshida, And Akiya Ogawa, Toshikazu HiraoAbstract:A variety of Ferrocenes bearing podand dipeptide chains have been synthesized to form an ordered structure in both solid and solution states and have been investigated by 1H NMR, FT-IR, CD, and X-ray crystallographic analyses. Conformational enantiomerization through chirality organization was achieved by the intramolecular hydrogen bondings between the podand dipeptide chains. The single-crystal X-ray structure determination of the Ferrocene 2 bearing the podand dipeptide chains (-d-Ala-d-Pro-OEt) revealed two C2-symmetric intramolecular hydrogen bondings between CO (Ala) and NH (another Ala) of each podand dipeptide chain to induce the chirality-organized structure. The molecular structures of the Ferrocene 1 composed of the podand l-dipeptide chains (-l-Ala-l-Pro-OEt) and 2 are in a good mirror image relationship, indicating that they are conformational enantiomers. An opposite helically ordered molecular arrangement was formed in the crystal packing of 2 as compared with 1. The Ferrocene 2 exhibited i...
Toshiyuki Moriuchi - One of the best experts on this subject based on the ideXlab platform.
-
intramolecular conformational control in Ferrocenes bearing podand dipeptide chains
Organometallics, 2001Co-Authors: Toshiyuki Moriuchi, Akihiro Nomoto, And Kazuhiro Yoshida, Toshikazu HiraoAbstract:Ferrocenes bearing podand dipeptide chains were demonstrated to induce intramolecular conformational regulation through hydrogen bondings. The single-crystal X-ray structure determination of the Ferrocene bearing the podand dipeptide chains -Gly-l-Pro-OEt confirmed the formation of two intramolecular interchain hydrogen bondings between CO (Gly) and NH (another Gly) of each podand dipeptide chain (N(1)···O(102), 2.910 A; N(101)···O(2), 2.898 A; N(201)···O(302), 2.85 A; N(301)···O(202), 2.87 A) to give a 10-membered hydrogen-bonded ring. The Ferrocene bearing the podand dipeptide chains -l-Pro-Gly-OEt is also considered to form two rigid intramolecular interchain hydrogen bondings between CO (bridging) and NH (another Gly) to give a 14-membered hydrogen-bonded ring. Such an ordered conformation was supported by the induced circular dichroism. On the other hand, the Ferrocene bearing one dipeptide chain -Gly-l-Pro-OEt is packed in a helically ordered arrangement with one turn of 15.65 A pitch height through...
-
chirality organization of Ferrocenes bearing podand dipeptide chains synthesis and structural characterization
Journal of the American Chemical Society, 2001Co-Authors: Toshiyuki Moriuchi, Akihiro Nomoto, Kazuhiro Yoshida, And Akiya Ogawa, Toshikazu HiraoAbstract:A variety of Ferrocenes bearing podand dipeptide chains have been synthesized to form an ordered structure in both solid and solution states and have been investigated by 1H NMR, FT-IR, CD, and X-ray crystallographic analyses. Conformational enantiomerization through chirality organization was achieved by the intramolecular hydrogen bondings between the podand dipeptide chains. The single-crystal X-ray structure determination of the Ferrocene 2 bearing the podand dipeptide chains (-d-Ala-d-Pro-OEt) revealed two C2-symmetric intramolecular hydrogen bondings between CO (Ala) and NH (another Ala) of each podand dipeptide chain to induce the chirality-organized structure. The molecular structures of the Ferrocene 1 composed of the podand l-dipeptide chains (-l-Ala-l-Pro-OEt) and 2 are in a good mirror image relationship, indicating that they are conformational enantiomers. An opposite helically ordered molecular arrangement was formed in the crystal packing of 2 as compared with 1. The Ferrocene 2 exhibited i...
Tim Albrecht - One of the best experts on this subject based on the ideXlab platform.
-
gold induced desulfurization in a bis ferrocenyl alkane dithiol
Organometallics, 2019Co-Authors: Evangelina Pensa, Nicholas J. Long, Rafal Karpowicz, Artur Jablonski, Damian Trzybinski, Krzysztof Woźniak, Davor Sakic, Valerije Vrcek, Tim AlbrechtAbstract:Thiol-modified Ferrocenes on gold have been archetypical model systems for many fundamental charge transfer and other studies, since both thiol-gold and Ferrocene redox chemistry are considered to be well-understood. Thus unexpectedly, we found that for a representative of a new class of flexibly linked bis-ferrocenyl compounds, namely, 1-10-bis(1-ferrocenyl)decane dithiol, surface immobilization on gold failed. Instead, in the presence of gold, molecular decomposition took place, resulting in sulfur-based adlayers and well-defined molecular elimination products, for which we provide spectroscopic evidence. Careful control experiments and comparison with related Ferrocene compounds provide insight into the mechanism of the observed elimination reactions, as a combined effect of the molecular structure and the nature of the gold/sulfur bond. These findings, thus, have a broader impact on the design of molecular adlayers, for example, in the context of surface functionalization in sensing or the synthesis o...
-
Gold-Induced Desulfurization in a Bis(ferrocenyl) Alkane Dithiol
2019Co-Authors: Evangelina Pensa, Nicholas J. Long, Rafal Karpowicz, Tim Albrecht, Artur Jabłoński, Damian Trzybiński, Krzysztof Woźniak, Davor Šakić, Valerije Vrček, Konrad KowalskiAbstract:Thiol-modified Ferrocenes on gold have been archetypical model systems for many fundamental charge transfer and other studies, since both thiol-gold and Ferrocene redox chemistry are considered to be well-understood. Thus unexpectedly, we found that for a representative of a new class of flexibly linked bis-ferrocenyl compounds, namely, 1-10-bis(1-ferrocenyl)decane dithiol, surface immobilization on gold failed. Instead, in the presence of gold, molecular decomposition took place, resulting in sulfur-based adlayers and well-defined molecular elimination products, for which we provide spectroscopic evidence. Careful control experiments and comparison with related Ferrocene compounds provide insight into the mechanism of the observed elimination reactions, as a combined effect of the molecular structure and the nature of the gold/sulfur bond. These findings, thus, have a broader impact on the design of molecular adlayers, for example, in the context of surface functionalization in sensing or the synthesis of gold nanoparticles
Eiichi Nakamura - One of the best experts on this subject based on the ideXlab platform.
-
Sharing orbitals: ultrafast excited state deactivations with different outcomes in bucky Ferrocenes and ruthenocenes.
Journal of the American Chemical Society, 2006Co-Authors: Dirk M. Guldi, G. M.aminur Rahman, Renata Marczak, Yutaka Matsuo, Masahiro Yamanaka, Eiichi NakamuraAbstract:We report on the singlet ground and singlet/triplet excited-state features of a series of bucky Ferrocenes, bucky ruthenocenes, and respective reference compounds. In the bucky Ferrocene conjugates, intimate contacts between the fullerenes and Ferrocenes result in appreciable ground-state interactionssuggesting a substantial shift of charge density from the electron donor (i.e., Ferrocene) to the electron acceptor (i.e., fullerene). In contrast, no prominent charge-transfer features were observed for the bucky ruthenocene conjugates. An arsenal of experimental techniques, ranging from fluorescence (i.e., steady state and time-resolved) and pump probe experiments (i.e., femtosecond and nanoseconds) to pulse radiolysis, were employed to examine excited-state interactions. In the excited states, bucky Ferrocene conjugates are dominated by rapid charge separation reactions (0.8 ± 0.1 ps) to yield metastable radical ion pairs. The radical ion pair lifetimes vary between 27 and 39 ps. No charge separation was, ...
-
synthesis of Ferrocene hydrofullerene hybrid and functionalized bucky Ferrocenes
Journal of the American Chemical Society, 2003Co-Authors: Motoki Toganoh, Yutaka Matsuo, Eiichi NakamuraAbstract:Hydroferration reaction of [60]fullerene or its derivative with [Fe(C5H5)(CO)2]2 gives regioselectively a Ferrocene/hydrofullerene hybrid, which upon treatment with Bu4NOH and an alkyl halide affords the corresponding alkylated bucky Ferrocene, again regioselectivity via an anion of the Ferrocene.
Shuli You - One of the best experts on this subject based on the ideXlab platform.
-
asymmetric c h bond functionalization of Ferrocenes new opportunities and challenges
Trends in Chemistry, 2020Co-Authors: Chenxu Liu, Shuli YouAbstract:Ferrocene is of great significance in the fields of organic synthesis, materials science, and biomedical research. Of particular importance is the fact that Ferrocenes with planar chirality have proven to be privileged ligands or catalysts for asymmetric catalysis. Therefore, developing highly efficient methods to introduce planar chirality on the backbone of Ferrocene is desirable. This short review highlights recent advances towards enantioselective C–H bond functionalization of Ferrocenes. Enantioselective synthesis of planar chiral Ferrocenes via Pd-, Ir-, Rh-, Au-, Pt-, and Ni-catalyzed C–H bond functionalization is described. The achievements in asymmetric C–H bond functionalization provide a rich platform for the design and synthesis of planar chiral Ferrocenes.
-
cp co iii catalyzed ortho c h amidation of 2 pyridinyl Ferrocenes with 1 4 2 dioxazol 5 ones
Journal of Catalysis, 2018Co-Authors: Shaobo Wang, Shuli YouAbstract:ortho-Amidation of 2-pyridinyl Ferrocenes with 1,4,2-dioxazol-5-ones was achieved via Cp*Co(III)-catalyzed direct C-H bond functionalization reaction. In the presence of Cp*Co(CO)I-2, in combination with AgPF6 and AgOPiv, a wide range of Ferrocene-based amidated products were obtained in up to 96% yield under mild reaction conditions. A gram-scale reaction proceeded smoothly with high efficiency. Isoquinoline and pyrimidine are also suitable directing groups in this transformation. (C) 2018 Elsevier Inc. All rights reserved.
-
enantioselective synthesis of planar chiral Ferrocenes via pd 0 catalyzed intramolecular direct c h bond arylation
Journal of the American Chemical Society, 2014Co-Authors: Dewei Gao, Qin Yin, Shuli YouAbstract:A highly efficient synthesis of planar chiral Ferrocenes by enantioselective Pd(0)-catalyzed direct C–H arylation from readily available starting materials under mild reaction conditions was developed (up to 99% yield, 99% ee). The products can be easily transformed to the highly efficient planar Ferrocene ligands, which have demonstrated high efficiency in Pd-catalyzed asymmetric allylic alkylation and amination reactions.
-
enantioselective synthesis of planar chiral Ferrocenes via palladium catalyzed annulation with diarylethynes
Beilstein Journal of Organic Chemistry, 2013Co-Authors: Yanchao Shi, Rongfei Yang, Dewei Gao, Shuli YouAbstract:When Boc-L-Val-OH was used as a ligand for the enantioselective Pd(II)-catalyzed annulation of N,N-substituted aminomethyl Ferrocene derivatives with diarylethynes, Ferrocenes with planar chirality could be achieved with excellent enantioselectivity (up to 99% ee).
