- A Concise Synthesis of Asymmetrically 4,5-Disubstituted 9,9-Dimethyl-9 H -xanthenes
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A concise synthesis of asymmetrically 4,5-disubstituted 9,9-dimethyl-9H-xanthenes was developed. The monolithiation of 4,5-dibromo-9H-xanthene, subsequent zincation, and the Negishi coupling with diverse electrophiles afforded the corresponding 4-aryl- or 4-vinyl-9H-xanthenes in good yields and with high selectivity. The second substitution reactions were performed under mild reaction conditions, thus providing a convenient synthetic route to functionalized molecules based on the 9H-xanthene skeleton.
- Matsubara, Ryosuke,Koide, Miki,Shin, Yong-Soon,Shimada, Toshiyuki,Hayashi, Masahiko
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- A Concise Synthesis of Asymmetrically 4,5-Disubstituted 9,9-Dimethyl-9 H -xanthenes
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A concise synthesis of asymmetrially 4,5-disubstituted 9,9-dimethyl-9H-xanthenes was developed. The monolithiation of 4,5-dibromo-9H-xanthene, subsequent zincation, and the Negishi coupling with diverse electrophiles afforded the corresponding 4-aryl- or 4-vinyl-9H-xanthenes in good yields and with high selectivity. The second substitution reactions were performed under mild reaction conditions, thus providing a convenient synthetic route to functionalized molecules based on the 9H-xanthene skeleton.
- Matsubara, Ryosuke,Koide, Miki,Shin, Yong-Soon,Shimada, Toshiyuki,Hayashi, Masahiko
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p. 187 - 192
(2015/08/25)
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- Congested cyclometalated platinum(II) ditopic frameworks and their phosphorescent responses to S-containing amino acids
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New phosphorescent platinum(II) molecular hosts featuring a tridentate N,C,N-coordinating ligand, a conformationally rigid organic linker, and a binding group have been prepared. The complexes have been fully characterized by various spectroscopic techniques, and the X-ray crystal structure of one derivative has been determined. Their photophysical properties have been studied, and intense green metal-perturbed 3IL emission is observed in solution at room temperature. The luminescent responses of these Pt(II) hosts to amino acids have been investigated: emission quenching and UV-vis absorption changes in polar/aqueous media are detected for terminal thiols only, and unusual preferential binding is apparent for cysteine over homocysteine. The nature of the host-guest interactions has been examined by quantitative and comparative binding studies, mass spectrometry, and DFT calculations, which indicate that these observations may be ascribed to the presence of rigidly positioned ditopic binding sites.
- Tong, Wah-Leung,Chan, Michael C. W.,Yiu, Shek-Man
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scheme or table
p. 6377 - 6383
(2011/02/17)
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- Synthesis and spectroscopic properties of modular platinum(II) terpyridine phosphorescent pockets
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A modular design approach has been utilized to develop molecular 'pockets' featuring three integrated components, namely a phosphorescent Pt(II)-π(organic) moiety, a suitable receptor group, and a rigid, conjugated connecting backbone, and the cavities therein are examined by NMR spectroscopy and an X-ray crystal structure. Their photophysical properties have been investigated; unusually for Pt-terpyridine derivatives, the complexes are luminescent (near-red 3MLCT emission) in solution at room temperature. It has been shown that their emissive characteristics are affected by the nature of the backbone component but not the receptor group. The Royal Society of Chemistry 2009.
- Tong, Wah-Leung,Chan, Michael C. W.,Zhu, Nianyong,Leung, Sze-Kar
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supporting information; scheme or table
p. 4741 - 4746
(2009/10/30)
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- Hangman salophens
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We report here a modular approach for the construction of a new class of compounds, the Hangman salophens. In the Hangman motif, an acid-base functionality "hangs" over the face of a redox cofactor. In contrast to more synthetically intractable porphyrin-based Hangman systems, Hangman salophens permit the facile control of their proton and redox properties for the study of the proton-coupled electron transfer (PCET) activation of small molecules. By investigating the catalase-like disproportionation of H2O2, we show that the presence (1) of a strong proton-donating hanging group (i.e., carboxylic acid) and (2) of electron-donating groups on the redox-active salen imparts significant catalytic activity for the O-O bond activation of small molecule substrates. The contribution of the new ligand framework to furthering our understanding of how PCET can be implemented in the design of active/selective catalysts will be discussed. Copyright
- Liu, Shih-Yuan,Nocera, Daniel G.
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p. 5278 - 5279
(2007/10/03)
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