35976-46-6Relevant articles and documents
Synthesis and properties of benzophenone-spiropyran and naphthalene-spiropyran conjugates
Tomasulo, Massimiliano,Kaanumal, Sireesha L.,Sortino, Salvatore,Raymo, Francisco M.
, p. 595 - 605 (2007/10/03)
We have designed and synthesized four compounds integrating luminescent and photochromic components in their molecular skeletons. Two of them combine a nitrospiropyran photochrome with either one or two naphthalene fluorophores and can be prepared in three synthetic steps. The other two consist of a nitrospiropyran photochrome and a benzophenone phosphore connected by either ether or ester linkages and can be prepared in six or five, respectively, synthetic steps. The luminescent components of these assemblies are expected to transfer energy intramolecularly to the photochromic species upon excitation and encourage their photoisomerization. Consistently, the phosphorescence of the benzophenone units and the fluorescence of the naphthalene components are effectively quenched when these species are connected covalently to a nitrospiropyran. Nonetheless, the photoisomerization of the photochrome becomes significantly less efficient after the covalent attachment to the luminescent partner. The fraction of incident radiations absorbed by either the benzophenone or the naphthalene fragment does not promote the isomerization of the photochromic appendage. Instead, irreversible transformations occur upon irradiation of the luminophore-photochrome assemblies. Thus, the covalent attachment of a benzophenone or a naphthalene to a nitrospiropyran is not a viable strategy to improve the photocoloration efficiency of the photochromic component. Even although the very same luminophores are known to sensitize intermolecularly the isomerization of nitrospiropyrans, the transition to covalent luminophore-photochrome assemblies tends to promote degradation, rather than sensitization, upon irradiation.
Structures of Lithium Salts of 2,3,3-Trimethylindolenine and Its 5-Methoxy Derivative in Solution and the Solid State
Jackman, L. M.,Scarmoutzos, L. M.,Smith, B. D.,Williard, Paul G.
, p. 6058 - 6063 (2007/10/02)
An X-ray crystal structure of lithium 2,3,3-trimethylindolenide etherate shows it to be a disolvated dimer having a η3-azaallyl-type structure.The structures of the salt in several solvents have been established by studies of 13C chemical shifts, 6Li, 15N spin-spin splitting, 7Li quadrupole splitting constants, and apparent degrees of aggregation determined by vapor pressure barometry.It is the η3-azaallyl dimer disolvate in diethyl ether, a tetrasolvated dimer in dioxolane, a mixture of monomer splitting constants of 230, 156, 180 - 190 (0.27 - 0.75 M), and 217 kHz, respectively.In diethyl ether with 4 equiv of hexamethylphosphoric triamide, the salt is a mixture of monomeric and triple ion species.Lithium 5-methoxy-2,3,3-trimethylindolenide forms similar species except that, in tetrahydrofuran, the tendency for dimer formation is enhanced, which leads to a higher proportion of C- to N-methylation in its reaction with methyl chloride in that solvent.
