A novel non-fluorescent rhodamine dye forms a twisted intramolecular charge transfer state. A substituent that causes steric hindrance is introduced at an ortho position of a dimethylamino group on the xanthene ring of tetramethylrhodamine, which is a general rhodamine that exhibits strong fluorescence, and a certain amount of twist is imparted in a ground state. As a result, the formation of the twisted intramolecular charge transfer state is promoted in the excited state and non-fluorescence is exhibited.
作者:Monica Pengshung、Patrick Neal、Timothy L. Atallah、Junho Kwon、Justin R. Caram、Steven A. Lopez、Ellen M. Sletten
DOI:10.1039/c9cc09671j
日期:——
utility of low energy light. The incorporation of silicon into xanthene and coumarin scaffolds has resulted in an array of visible and near-infrared fluorophores. Here, we extend this approach to polymethinedyes, another popular fluorophore class, performing experimental and computational analyses. We found that when oxygen was replaced with SiMe2, bathochromic shifts of up to 121 nm and fluorophores
Improved Xanthone Synthesis, Stepwise Chemical Redox Cycling
作者:James L. Bachman、P. Rogelio Escamilla、Alexander J. Boley、Cyprian I. Pavlich、Eric V. Anslyn
DOI:10.1021/acs.orglett.8b03661
日期:2019.1.4
A base-catalyzed direct oxidation of rhodamine, carborhodamine, and siliconrhodamine pyronines to the corresponding xanthones is studied. This methodology utilizes addition of water to split pyronines into xanthone and reduced xanthene, the latter of which is returned to pyronine by oxidation with iodine. The transformation is general, working on the three most recalcitrant versions of N,N,N′,N′-tetramethylpyronines