Acyclic O- and N-substituted pentadienyl cations: Structural characterisation, cyclisation and computational results
摘要:
A number of 1- and 3-hydroxy and 1-amino substituted acyclic pentadienyl cations have been characterised by NMR spectroscopy in situ at low temperature. Some of the 3-hydroxy cations undergo cyclisation to give 1-hydroxycyclopentenyl cations which on deprotonation give substituted cyclopentenones.
Abstract
In this study, near-infrared absorbing rotaxane-type cyanine dyes exhibit high tolerance to various chemical reactions, which is attributed to the encapsulation effect of their cyclic molecules. As a result, rotaxane dyes can be post-modified on the host α-cyclodextrin or guest cyanine skeleton to adjust their solubility, absorption wavelength, stability, and singlet oxygen generation ability. The guest modification product obtained via the Heck reaction demonstrates a red shift of its absorption wavelength owing to the extended conjugation system. Moreover, the products of host modification through the methylation and benzylation of all cyclodextrin hydroxyl groups not only become lipophilic and show extended absorption, but also exhibit higher photooxidation tolerance, lower singlet oxygen generation rate, and increased singlet oxygen tolerance, indicating their potential applicability as highly durable dyes. Furthermore, the outstanding singlet oxygen tolerance of these dyes enables their use in long-life singlet oxygen generators, in which the total amount of singlet oxygen increases. This work demonstrates that an intrinsically unstable near-infrared cyanine dye can be used as a synthetic intermediate by stabilizing it via α-cyclodextrin encapsulation, allowing the post-modification of various properties of cyanine dyes toward the higher-order near-infrared-absorbing materials with complex functionalities and diverse utilities.
A Complex Comprising a Cyanine Dye Rotaxane and a Porphyrin Nanoring as a Model Light‐Harvesting System
作者:Jiratheep Pruchyathamkorn、William J. Kendrick、Andrew T. Frawley、Andrea Mattioni、Felipe Caycedo‐Soler、Susana F. Huelga、Martin B. Plenio、Harry L. Anderson
DOI:10.1002/anie.202006644
日期:2020.9.14
A nanoring‐rotaxane supramolecularassembly with a Cy7 cyaninedye (hexamethylindotricarbocyanine) threaded along the axis of the nanoring was synthesized as a model for the energy transfer between the light‐harvesting complex LH1 and the reaction center in purple bacteria photosynthesis. The complex displays efficient energy transfer from the central cyaninedye to the surrounding zinc porphyrin nanoring
Stabilisation of a heptamethine cyanine dye by rotaxane encapsulation
作者:C. M. Simon Yau、Sofia I. Pascu、Susan A. Odom、John E. Warren、Eric J. F. Klotz、Michael J. Frampton、Charlotte C. Williams、Veaceslav Coropceanu、Marina K. Kuimova、David Phillips、Stephen Barlow、Jean-Luc Brédas、Seth R. Marder、Val Millar、Harry L. Anderson
DOI:10.1039/b802728e
日期:——
The crystal structure of a cyaninedye rotaxane shows that the cyclodextrin is tightly threaded round the polymethine bridge of the dye; encapsulation dramatically increases the kinetic chemical stability of the radicals formed on oxidation and reduction of the dye, making it possible to observe the rotaxane radical dication by ESR and UV-vis-NIR spectroscopy.
Strategies for remote enantiocontrol in chiral gold(<scp>iii</scp>) complexes applied to catalytic enantioselective γ,δ-Diels–Alder reactions
作者:Jolene P. Reid、Mingyou Hu、Susumu Ito、Banruo Huang、Cynthia M. Hong、Hengye Xiang、Matthew S. Sigman、F. Dean Toste
DOI:10.1039/d0sc00497a
日期:——
square planar gold(III) complexes to access enantioenriched products has rarely been applied in asymmetric catalysis. In this context, we report a mechanistic and synthetic investigation into the use of N-heterocyclic (NHC) gold(III) complexes in γ,δ-Diels–Alder reactions of 2,4-dienals with cyclopentadiene. The optimal catalyst bearing a unique 2-chloro-1-naphthyl substituent allowed efficient synthesis
Baumgarten, Chemische Berichte, 1924, vol. 57, p. 1624
作者:Baumgarten
DOI:——
日期:——
Acyclic O- and N-substituted pentadienyl cations: Structural characterisation, cyclisation and computational results
作者:James A.S. Howell、Paula J. O'Leary、Paul C. Yates、Zeev Goldschmidt、Hugo E. Gottlieb、Daphna Hezroni-Langerman
DOI:10.1016/0040-4020(95)00369-j
日期:1995.6
A number of 1- and 3-hydroxy and 1-amino substituted acyclic pentadienyl cations have been characterised by NMR spectroscopy in situ at low temperature. Some of the 3-hydroxy cations undergo cyclisation to give 1-hydroxycyclopentenyl cations which on deprotonation give substituted cyclopentenones.