Current developments in optical data storage with organic dyes

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.     

Determination of the enthalpy of fusion of K<Subscript>3</Subscript>TaO<Subscript>2</Subscript>F<Subscript>4</Subscript> and KTaF<Subscript>6</Subscript>

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.     

Dye,fluorophores and pigment coloration of nanofibers produced by electrospinning

Polymeric nanofibers produced by the electrospinning technique are widely used in industrial scale production. Nanofibers chiefly find applications in filtration media and active–barrier surfaces for medical, biological, and military applications. In such applications, the quantity and the uniformity of the nanofibers distribution play a leading role in the product characteristics. For this reason, there is considerable interest regarding the nanofibers recovering quantification and simplification of the qualitative analysis. With the aim to improve and simplify the nanofibers relevability, a coloration approach for nanofibers has been designed and tested. The coloration has been carried out by organic dyes, pigments, and organic fluorophores and the consequent nanofibers' color has been analyzed by optical analysis, colorimetry, and spectroscopy. The coloration obtained by different dyes has been compared and their effect on the nanofibers relevability has been investigated. Moreover, the leading role of the light scattering phenomenon on the nanofiber coloration efficacy has been investigated by comparing the coloration response of nanofibers and film samples on equal terms of dye content. The study has been carried out using polyamide‐6 (PA6) as the testing polymer but the recovering quantification, the coloration approach, and the interaction between light and nanofibers can be extended to all the electrospinnable polymers. Copyright © 2008 John Wiley & Sons, Ltd.     

Functionalization of Boron Dipyrrin (BODIPY) Dyes through Iridium and Rhodium Catalysis: A Complementary Approach to α‐ and β‐Substituted BODIPYs

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.

     

Construction of Helical J‐Aggregates Self‐Assembled from a Thymidylic Acid Appended Anthracene Dye and DNA as a Template

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.

     

Novel Molecular Building Blocks Based on the Boradiazaindacene Chromophore: Applications in Fluorescent Metallosupramolecular Coordination Polymers

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.

     

Turinese Stereochemistry: Eligio Perucca's Enantioselectivity and Primo Levi's Asymmetry

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.

     

A New Two‐Photon‐Sensitive Block Copolymer Nanocarrier

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.