Papers by Luisa Lascialfari
Soft matter, Jan 9, 2015
The effect of the replacement of molecular moieties (carbamates vs. urea) that drive self-assembl... more The effect of the replacement of molecular moieties (carbamates vs. urea) that drive self-assembly for two organogelators with an identical C2 symmetric molecular structure is described. The main properties of the gels obtained from the urea-based organogelators are also discussed. The proposed organogelators are chiral molecules and are able to express chirality also at the supramolecular level, thus allowing the employment of electronic circular dichroism to gain insight into the molecular-scale structure of fibrillar aggregates. With the same technique, the behavior of enantiomeric mixtures of the urea-based organogelators was investigated, revealing the occurrence of different self-sorting phenomena at the molecular and supramolecular scale. The urea-based organogelators demonstrated to be more efficient gelators with respect to the carbamate-based analogues, showing a high gel-to-sol transition temperature (up to 66 °C) and a very low minimum gelling concentration (0.85 mg mL(-...
Chirality, Jan 14, 2015
Chiral discrimination in a racemic mixture of dipalmitoylphosphatidylcholine (DPPC) is induced by... more Chiral discrimination in a racemic mixture of dipalmitoylphosphatidylcholine (DPPC) is induced by a new selector at the water-air interface: L-DPPC is segregated in the condensed phase of a Langmuir monolayer upon interactions with an enantiopure amphiphilic compound. Chirality 00:000-000, 2015. © 2015 Wiley Periodicals, Inc.
Journal of colloid and interface science, Jan 15, 2015
We assessed a method for the preparation of small, highly stable and unprotected Pd nanoparticles... more We assessed a method for the preparation of small, highly stable and unprotected Pd nanoparticles by picosecond laser ablation in 2-propanol. The nanoparticles can be extracted from 2-propanol by centrifugation and redispersed in water, where a strongly negative ζ-potential assures long term stability. The proposed procedure permits reduction of particle size down to 1.6nm and optimization of the Pd(0):Pd(II) ratio which, in the best cases, was of the order of 6:1. The increase of this ratio with ablation times has been correlated to the high temperature conversion of PdO to metallic Pd by a simple theoretical model. A study of the relationship between colloid absorption at 400nm and Pd concentration permitted the role of PdO in the determination of the UV-vis spectra to be clarified and the limits of the Mie theory for the evaluation of colloid concentration to be established. The absorption at 400nm can be used as a fast method to estimate the Pd content in the colloids, provided ...
The Journal of Physical Chemistry C, 2014
ChemPlusChem, 2013
Abstract A chiral organogelating scaffold is functionalised with a stable organic radical pendant... more Abstract A chiral organogelating scaffold is functionalised with a stable organic radical pendant. The morphology and spectroscopic properties of the gels are investigated as a function of the organogelator concentration and temperature. The combination of AFM and ESR spectroscopy provides firm evidence that the architecture responsible for the formation of the macroscopic gel (ie, the fibrillar structure) is maintained below the gelling concentration. This opens relevant perspectives in terms of the realisation of complex ...
Thin Solid Films, 2014
The production of nanohybrids formed by oxidized multiwalled carbon nanotubes (MWCNTs) and nanopa... more The production of nanohybrids formed by oxidized multiwalled carbon nanotubes (MWCNTs) and nanoparticles, produced by pulsed laser ablation in liquids process, is described. The use of linkers, obtained by transformation of pyrene-1-butanol, is mandatory to generate an efficient and stable interaction between the two components. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis showed the obtainment of the efficient coverage of the MWCNTs by nanoparticles composed by metal gold and, partially, by oxides.
Progress in Heterocyclic Chemistry, 2014
Thin Solid Films, 2013
ABSTRACT Colloidal dispersions of silver and gold nanoparticles were obtained in pure water by ab... more ABSTRACT Colloidal dispersions of silver and gold nanoparticles were obtained in pure water by ablation with nanosecond pulsed laser. Then, by filtration of the metal particles on alumina, we fabricated nanostructured films, whose surface morphology was examined by atomic force microscopy (AFM) and related to surface-enhanced Raman scattering (SERS) after adsorption of adenine.
Soft Matter, 2011
The organic functionalization of either [60] fullerene or MWCNTs with a highly efficient organoge... more The organic functionalization of either [60] fullerene or MWCNTs with a highly efficient organogelator has allowed the production of novel and homogeneously dispersed soft-nanocomposites. While the nanostructured carbon materials produced by simple mixing do not homogeneously disperse into a preformed gel, C60-and MWCNT-containing gels have been conveniently obtained by covalent functionalization of the carbon lattice with reactive organogelator derivatives. The present study, while emphasizing the gelling properties of ...
Soft Matter, 2014
The purpose of this study is to compare the gelling behavior of two molecules: a chiral compound ... more The purpose of this study is to compare the gelling behavior of two molecules: a chiral compound and its achiral counterpart. The chiral partner is characterized by a rigid, chiral pyrrolidine nucleus, while the achiral one contains a flexible diethanolamine moiety. The chiral compound is an already known good organogelator, but also the achiral compound shows remarkable gelling properties. Very interestingly, a small fraction of the chiral compound induces chirality and strong CD effects in its aggregates with the achiral one. The observed chirality amplification corresponds to a peculiar sergeant-and-soldier effect. Molecular modelling and CD calculations suggested a model for the supramolecular assembly of hetero-aggregates that fits the experimental data.
Soft Matter, 2010
(3S, 4S)-1-benzylpyrrolidine-3, 4-diyl bis (dodecylcarbamate), a pyrrolidine ring bearing two lon... more (3S, 4S)-1-benzylpyrrolidine-3, 4-diyl bis (dodecylcarbamate), a pyrrolidine ring bearing two long carbon chains connected by carbamate functionalities, is the origin of stable gels in both polar and apolar solvents. Several experimental and theoretical techniques (cryo-TEM, AFM, DSC, circular dichroism (CD), molecular mechanics calculations and CD simulations) were used to describe the formation and the characteristics of the chiral supramolecular structures and fibers constituting the gel. The chirality at both supramolecular and ...
Soft Matter, 2009
A new organogelating moiety, 1, is proposed as a suitable and versatile building block for the pr... more A new organogelating moiety, 1, is proposed as a suitable and versatile building block for the production of other gelling compounds. Linking 1 with several different molecular fragments afforded new gels with different properties. A detailed investigation of the ferrocene substituted gelator is reported in this study.
Physical Chemistry Chemical Physics, 2014
In this work we present the synthesis, time-resolved spectroscopic characterization and computati... more In this work we present the synthesis, time-resolved spectroscopic characterization and computational analysis of a bichromophore composed of two very well-known naturally occurring dyes: 7-hydroxycoumarin (umbelliferone) and 1,2-dihydroxyanthraquinone (alizarin). The umbelliferone donor (Dn) and alizarin acceptor (Ac) moieties are linked to a triazole ring viaσ bonds, providing a flexible structure. By measuring the fluorescence quantum yields and the ultrafast transient absorption spectra we demonstrate the high efficiency (∼85%) and the fast nature (∼1.5 ps) of the energy transfer in this compound. Quantum chemical calculations, within the density functional theory (DFT) approach, are used to characterize the electronic structure of the bichromophore (Bi) in the ground and excited states. We simulate the absorption and fluorescence spectra using the TD-DFT methods and the vertical gradient approach (VG), and include the solvent effects by adopting the conductor-like polarizable continuum model (CPCM). The calculated electronic structure suggests the occurrence of weak interactions between the electron densities of Dn and Ac in the excited state, indicating that the Förster-type transfer is the appropriate model for describing the energy transfer in this system. The average distance between Dn and Ac moieties calculated from the conformational analysis (12 Å) is in very good agreement with the value estimated from the Förster equation (∼11 Å). At the same time, the calculated rate constant for energy transfer, averaged over multiple conformations of the system (3.6 ps), is in reasonable agreement with the experimental value (1.6 ps) estimated by transient absorption spectroscopy. The agreement between experimental results and computational data leads us to conclude that the energy transfer in Bi is well described by the Förster mechanism.
Optical Engineering, 2014
We developed Hg 2þ -sensing chips by decorating the external surface of metal-clad optical wavegu... more We developed Hg 2þ -sensing chips by decorating the external surface of metal-clad optical waveguides with a monolayer of Hg 2þ -sensitive fluorescent molecular probes. The emission properties of the original water-soluble form of the molecule were previously found to be selectively quenched in the presence of Hg 2þ ions. The fabricated samples were tested with optical waveguide fluorescence spectroscopy by putting them in contact with a 5-μM water solution of Hg 2þ ions and recording the emission spectra versus incubation time. The estimate of the limit of detection was 150 nM. A preliminary evaluation of the selectivity of the structure was also performed by using Cd 2þ as possible interfering analytes.
Journal of Molecular Structure, 2011
The choice of a donor and an acceptor with suitable optical and self-assembly properties is essen... more The choice of a donor and an acceptor with suitable optical and self-assembly properties is essential in the design of organogel-based light harvesting systems. Organogels can provide supramolecular structures capable of enhancing energy transfer processes. In this work, we present the characterization of N-(naphthalene-1-carboxyamide)-(3S,4S)-pyrrolidin-(3,4)-bisdodecyl-carbamoyldiester (1) and N-(4-nitrobenzofurazan-7-amino)-(3S,4S)-pyrrolidin-(3,4)-bisdodecyl-carbamoyldiester (2) which are used as donor and acceptor moieties, respectively. The donor molecule
Chirality, 2011
In this work, we present the characterization of an enantiomeric pair of fluorescent dye organoge... more In this work, we present the characterization of an enantiomeric pair of fluorescent dye organogelators and the properties of their stable gel at low concentration in organic solvents. The gels of both enantiomers and of their mixtures were analyzed by differential scanning calorimetry, circular dichroism (CD), atomic force microscopy, UV-vis absorption, and fluorescence. The acquired data were supported by molecular modeling of the helical assembly of the gelators and by the simulation of their CD spectra by means of DeVoe method, and suggested the occurrence of an enantiomeric discrimination process during the formation of the gels.
Chemical Communications, 2010
An unprecedented functionalization of multi-walled carbon nanotubes (MWCNTs) has been convenientl... more An unprecedented functionalization of multi-walled carbon nanotubes (MWCNTs) has been conveniently achieved by the 1,3-dipolar cycloaddition of a cyclic nitrone. This organic functionalization yields materials with a great solubility in DMF (close to 10 mg per mL of DMF) preferentially occurring at the defects of the MWCNT sp(2) network.
Chemical Communications, 2007
The synthesis and the properties of a new chiral organogelator based on a C(2) symmetric pyrrolid... more The synthesis and the properties of a new chiral organogelator based on a C(2) symmetric pyrrolidine, are described together with its use for the synthesis of other functionalised organogelators.
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Papers by Luisa Lascialfari