Detection and Memory of Nonracemic Molecules by a Racemic Host Polymer Film
Università degli Studi di Salerno, Fisciano, Campania, ItalyJournal of the American Chemical Society (Impact Factor: 12.11). 10/2007; 129(36):10992-3. DOI: 10.1021/ja0732936
Robust syndiotactic polystyrene films, presenting a suitable nanoporous host crystalline phase, are able to transfer, amplify, and memorize the chirality of nonracemic low-molecular-mass molecules. In fact, after temporary exposure to volatile nonracemic guests, the polymer films present intense induced circular dichroism (ICD) phenomena. These ICD phenomena are associated with the temporary formation of polymer/guest cocrystalline phases.
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- "e l s e v i e r . c o m / l o c a t e / c a r b o n present in traces and hence suitable for molecular separation     , sensor       and catalysis   applications. "
ABSTRACT: Robust monolithic aerogels based on syndiotactic polystyrene (s-PS) and graphene oxide (GO), and exhibiting high surface areas (240-290 m2/g) and low density (0.02-0.2 g/cm3), are presented. These aerogels are obtained by supercritical carbon dioxide extraction of s-PS/GO gels, which were prepared by s-PS dissolution in GO dispersions in suitable organic solvents. In contrast to other GO-based aerogels, the s-PS/GO aerogels are blue, not black. This blue color is due to Rayleigh scattering by isolated particles of reduced graphene oxide, whose thickness is much smaller than the wavelength of the light. The s-PS/GO aerogels exhibit the functionalities of the nanoporous-crystalline δ form of the polymer and of reduced and structurally uncorrelated GO layers and maintain the ductility of pure polymer aerogels. Uses can be anticipated as supported GO-based catalyst or “masterbatches” for GO rich nanocomposites.Carbon 10/2014; 77:896-905. DOI:10.1016/j.carbon.2014.06.003 · 6.20 Impact Factor
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- "The occurrence of transfer and amplification of chiral information is particularly relevant for solid polymer films, since they could have in principle applications in chirooptical devices and data storage systems. Recently, is has been reported that non-racemic s-PS films are able to detect, amplify and memorize the chirality of several volatile organic molecules [123,124]. "
ABSTRACT: Chemical sensors are generally based on the integration of suitable sensitive layers and transducing mechanisms. Although inorganic porous materials can be effective, there is significant interest in the use of polymeric materials because of their easy fabrication process, lower costs and mechanical flexibility. However, porous polymeric absorbents are generally amorphous and hence present poor molecular selectivity and undesired changes of mechanical properties as a consequence of large analyte uptake. In this contribution the structure, properties and some possible applications of sensing polymeric films based on nanoporous crystalline phases, which exhibit all identical nanopores, will be reviewed. The main advantages of crystalline nanoporous polymeric materials with respect to their amorphous counterparts are, besides a higher selectivity, the ability to maintain their physical state as well as geometry, even after large guest uptake (up to 10-15 wt%), and the possibility to control guest diffusivity by controlling the orientation of the host polymeric crystalline phase. The final section of the review also describes the ability of suitable polymeric films to act as chirality sensors, i.e., to sense and memorize the presence of non-racemic volatile organic compounds.Sensors 12/2009; 9(12):9816-57. DOI:10.3390/s91209816 · 2.25 Impact Factor
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ABSTRACT: Thermal transitions of the three crystalline phases (γ, δ, and) of syndiotactic polystyrene (s-PS), presenting s(2/1)2 helices, have been compared by X-ray diffraction, differential scanning calorimetry (DSC), and dynamic-mechanical analyses. These analyses have been conducted on crystalline (δ and) films, obtained by similar solvent sorption and desorption procedures, starting from a same γ-form film. The Fourier transform Infrared (FTIR) spectra of the three films have also been compared. The obtained results indicate that the recently discovered -phase, as the already known δ-phase, is transformed in γ-phase by heating above 100 °C. However, the f γ transition occurs directly without the formation, for intermediate temperatures, of a helical mesomorphic phase, as instead observed for the δ f γ transition. DSC studies and FTIR measurements also suggest that the crystalline packing of the -form could be rather similar to that one of the γ-form.Macromolecules 12/2007; 40(26). DOI:10.1021/ma071640q · 5.80 Impact Factor
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