| 1. |
- D'Annibale, Valeria, et al.
(author)
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A spectroscopic and structural study on the solvent-promoted stereospecific self-assembly of new Porphyrin-Bile Salt conjugates
- 2024
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In: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - 0927-7757. ; 700
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Journal article (peer-reviewed)abstract
- The chiral bile salt sodium cholate has been covalently linked to tetra-aryl-porphyrins, conferring them an extrinsic chirality and obtaining new molecules with high tendency to aggregate in solution. The chirality transfer from the molecular to the nano- and meso-scale has been investigated by promoting the self-assembly of the conjugates balancing the ratio of aqueous/organic solvent mixtures and allowing a fine control of the dimensions and morphology of the final supramolecular architectures. The shift from elongated structures with helical ribbon features to monodisperse tubules or from tightly packed rolled sheets to wrapped scrolls was enabled by changing the solvent composition, with the possibility of forming tubular structures with a hollow cavity. From UV–Vis and Circular Dichroism (CD) spectroscopy the ability to self-assemble into J-type aggregates with a strong induction of supramolecular chirality was revealed, shedding light on a two-step process, with a fast monomer nucleation followed by a slow second step of further stereospecific chiral evolution. The results as a whole promote the new porphyrin-cholate conjugates as promising smart and easily tunable chiral materials for the design of stereoselective sensing devices.
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| 2. |
- Dini, Francesca, et al.
(author)
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Chemical sensitivity of self-assembled porphyrin nano-aggregates
- 2009
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In: NANOTECHNOLOGY. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 20:5, s. 055502-
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Journal article (peer-reviewed)abstract
- Nanostructured molecular assemblies may provide additional sensing properties not found in other arrangements of the same basic constituents. Among three-dimensional structures, nanotubes are particularly appealing for applications as chemical sensors, because of the potential inclusion of different guests inside the cavity or the induced modification of the skeletal interaction after analyte binding. Porphyrins are a class of compounds characterized by brilliant sensing properties, appearing also in non-ordered solid-state aggregates. In recent years, it was reported that aggregation of oppositely charged porphyrins led to the formation of self-assembled nanotubes and in this paper their sensing properties, both in solution and in the solid state, have been investigated. The interactions of porphyrin nanotubes with guest molecules have been monitored by following the changes in their UV-vis spectra. The results obtained have been exploited to build up a sensing platform based on a computer screen as a light source and a digital camera as detector. Porphyrin nanostructures exhibited an enhanced sensitivity to different compounds with respect to those shown by single porphyrin subunits. The reason for the increased sensitivity may be likely found in an additional sensing mechanism related to the modulation of the strength of the forces that keep the supramolecular ensemble together.
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