The main motivation for the development of digital data storage has been the improvement in play‐back quality and the increase in storage capacity. In 1982 Philips and Sony introduced the first technically and economically successful system based on this—the compact disc (CD) and a compatible player. A very broad diversity of optical data recording formats are available today, and a difference is drawn between prerecorded, recordable, and rewritable media. This Review gives an overview of the systems used, the main features of production, and then concentrates on the properties of the organic dyes that are used in recordable systems. Dyestuffs chemistry has gained the reputation of having become a mature field of activity. Is this prejudice or a justified swan song for dyestuffs chemistry? When applications in optical data storage are considered, it is evident that even today progresses such as CD‐R and DVD/R would not be feasible without functional dyes. 相似文献
Areas of fusion and crystallization peaks of K3TaO2F4 and KTaF6 were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering
the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K3TaO2F4 at the fusion temperature of 1181 K of (43 ± 4) kJ mol−1 and of KTaF6 at the fusion temperature of 760 K of (8 ± 1) kJ mol−1 were determined. 相似文献
Two series of BODIPY dyes with substituents either in the α positions or in the β positions and different conjugation lengths were synthesized by means of iridium‐catalyzed borylation and rhodium‐catalyzed Heck‐type addition (see scheme). The α‐ and β‐substituted series show completely different photophysical properties. BODIPY=boron dipyrrin.
Driven round the twist by DNA : One‐dimensional helical J‐aggregates are formed by the self‐assembly of thymidylic acid appended anthracene dye (shown in red and yellow) in the presence of complementary single‐stranded oligoadenylic acid (shown in green and blue) in an aqueous solution.
Bright polymers : Fluorescent coordination polymers made up of versatile functionalized bodipy (boron‐dipyrrin) chromophore building blocks, such as that depicted, are described. Polymerization is signaled by changes in fluorescence emission intensity and shifts in peak emission wavelengths.
A reputation restored : Eligio Perucca (see photo) first observed the enantioselective adsorption of a racemic mixture to a chiral crystal (NaClO3) in Turin in 1919. However, this milestone in enantioselective chemistry and chiroptics went unnoticed. Identified previously as a coward who refused in 1941 to supervise the research of the budding stereochemist Primo Levi because of the race laws, Perucca was opposed to the fascist regime.
Easily disrupted : Micelles of a new amphiphilic block copolymer that bear coumarin groups are sensitive to near infrared light by two‐photon absorption of the chromophore. Disruption of the micelles under irradiation at 794 nm results in release of both photocleaved coumarin and encapsulated nile red from the hydrophobic core of micelle into aqueous solution, which results in opposing changes in fluorescence emission intensity.