169030-64-2Relevant academic research and scientific papers
Switchable Mesomeric Betaines Derived from Pyridinium-Phenolates and Bis(thienyl)ethane
Adams, J?rg,Dahle, Sebastian,Hübner, Eike G.,Lederle, Felix,Maus-Friedrichs, Wolfgang,Nagorny, Sven,Schmidt, Andreas,Udachin, Viktor,Weingartz, Thea
, p. 3178 - 3189 (2021/07/02)
Syntheses of push–pull substituted non-symmetric bis(thienyl)ethenes (BTEs) possessing a central perfluorocyclopentene core are described. The substituent effects of anisole, phenole, and phenolate as well as pyridine, pyridinium, and N-methylpyridinium substituents, joined through their 3- or 4-positions to the central BTE core, respectively, cover the range from very strongly electron-donating [σ(4-phenolate)=?1.00] to extremely strongly electron-withdrawing [σ(pyridinium-4-yl)=+2.57] in the title mesomeric betaines. The different isomers possessing 4-yl/4-yl, 4-yl/3-yl and 3-yl/3-yl substituents represent different combinations of conjugated and cross-conjugated partial structures and cause different spectroscopic properties. In addition, through-space conjugation between the 2- and 2′-position of the thiophenes can be observed which circumvents the charge-separation of through-bond cross-conjugation. The BTE possessing the push–pull chromophore consisting of 3-anisole and 4-pyridinium substituents (24) displays the best extinction coefficients within the series of compounds described here (?=33.8/15.7 L/mol ? cm), while the mesomeric betaine possessing an N-methylpyridinium-4-yl and a 4-phenolate substituent (29) displays considerable bathochromic shifts to λmax=724 nm in its closed form.
Photochemical pK(a)-modulation and gated photochromic properties of a novel diarylethene switch
Kawai, Stephen H.,Gilat, Sylvain L.,Lehn, Jean-Marie
, p. 2359 - 2366 (2007/10/03)
The unsymmetrical dithlenylethene photochrome 1a exhibits proton-gated photochromic properties as well as novel chemical reactivity. The dimethoxylated derivative 9a represents a light-triggered proton switch whose dissociation constant is increased by a factor of 16 upon photochemical cyclization to 9b. Such compounds are of potential interest for multiplexing photochemical systems.
Optical switching and fluorescence modulation properties of photochromic metal complexes derived from dithienylethene ligands
Fernandez-Acebes, Alvaro,Lehn, Jean-Marie
, p. 3285 - 3292 (2007/10/03)
Organic photochromic systems represent a starting point for the preparation of light-triggered molecular switching devices. The novel dithienylethene-tungsten (1,2), rhenium (3,4), and ruthenium (5) complexes were synthesized from their parent ligands. The biscyano photochromic complexes 14 and 16 were also prepared although their metallic complexes could not be isolated. All the compounds described exhibited pronounced photochromic properties. Irradiation of the open forms of complexes 1-4 with UV light resulted in essentially quantitative photocyclization to the deeply colored closed forms; the colorless open forms could be regenerated by irradiation with visible light of λ>600 nm. Compounds 1-4 were found to display a fluorescence discrimination between their open and closed forms when excited at wavelengths (240 nm) that almost did not affect the state of the system. Finally the closed form of product 5, prepared from the closed form of its parent ligand, was photochemically stable. Thus, the molecules 1-5 represent two kinds of non-destructive read-out models.
