André L.A. Parussulo

Sevenfold enhancement on porphyrin dye efficiency by coordination of ruthenium polypyridine complexes.

Sevenfold enhancement of photoconversion efficiency was achieved by incorporation of peripheral ruthenium complexes to a porphyrin dye, generating supramolecular effects capable of playing several key roles (e.g., transferring energy to, inhibiting aggregation, and accepting the hole generated in the porphyrin center after electron injection), providing new insights for the design of better DSSC photosensitizers.

Unravelling the Chemical Morphology of a Mesoporous Titanium Dioxide Interface by Confocal Raman Microscopy: New Clues for Improving the Efficiency of Dye Solar Cells and Photocatalysts

The presence of anatase and rutile domains on nanocrystalline films of P25 TiO2, as well as the distinct coordination modes of carboxylates on those phases, were revealed by confocal Raman microscopy, a technique that showed to be suitable for imaging the chemical morphology down to submicrometric size.

N3-dye-induced visible laser anatase-to-rutile phase transition on mesoporous TiO2 films.

Titanium dioxide has been extensively used in photocatalysis and dye-sensitized solar cells, where control of the anatase-to-rutile phase transformation may allow the realization of more efficient devices exploiting the synergic effects at anatase/rutile interfaces. Thus, a systematic study showing the proof of concept of a dye-induced morphological transition and an anatase-to-rutile transition based on visible laser (532 nm) and nano/micro patterning of mesoporous anatase (Degussa P25 TiO(2)) films is described for the first time using a confocal Raman microscope. At low laser intensities, only the bleaching of the adsorbed N3 dye was observed. However, high enough temperatures to promote melting/densification processes and create a deep hole at the focus and an extensive phase transformation in the surrounding material were achieved using 1s laser pulses of 25-41 mW/cm(2), in resonance with the MLCT band. The dye was shown to play a key role, being responsible for the absorption and efficient conversion of the laser light into heat. As a matter of fact, the dye is photothermally decomposed to amorphous carbon or to gaseous species (CO(x), NO(x), and H(2)O) under a N(2) or O(2) atmosphere, respectively.

Evaluation of Sun Protection Factor of Cosmetic Formulations by a Simple Visual In Vitro Method Mimicking the In Vivo Method

A new concept for in vitro visual evaluation of sun protection factor (SPF) of cosmetic formulations based on a supramolecular ultraviolet (UV) dosimeter was clearly demonstrated. The method closely parallels the method validated for in vivo evaluation and relies on the determination of the slightest perceptible bleaching of an iron-complex dye/nanocrystalline-titanium dioxide interface (UV dosimeter) in combination with an artificial skin substrate simulating the actual human skin in the presence and absence of a cosmetic formulation. The successful evaluation of SPF was ensured by the similarity of the erythema response of our dosimeter and human skin to UV light irradiation. A good linear correlation of in vitro and in vivo data up to SPF 40 confirmed the effectiveness of such a simple, cheap, and fast method. In short, here we unravel a convenient and accessible visual FPS evaluation method that can help improving the control on cosmetic products contributing to the reduction of skin cancer, one of the critical public health issues nowadays.

How relevant can the SERS effect in isolated nanoparticles be

Gold nanoparticles electrostatically stabilized with negatively charged ruthenium complexes were individually monitored based on their characteristic plasmon bands, by means of hyperspectral dark field microscopy. Very strong SERS enhancements were observed for the isolated gold nanoparticles at exciting wavelengths in resonance with the surface plasmon band, using confocal Raman microscopy, revealing a contrasting behaviour between the agglomerated and non-agglomerated systems. The results highlighted the relevant role played by the surface enhanced resonance Raman mechanisms (SERRS) in isolated nanoparticles, more than compensating for the lack of local hot spots, in relation to the agglomerated systems.

Unraveling the Mysterious Role of Palladium in Feigl bis(dimethylglyoximate)nickel(II) Spot Tests by Means of Confocal Raman Microscopy

The acid protection effect promoted by traces of PdCl(2) in [Ni(dmgH)(2)] spot tests was elucidated from confocal Raman microscopy imaging, which revealed the formation of protecting layers of [Pd(dmgH)(2)] closing the extremities of the [Ni(dmgH)(2)] filaments.

Gold nanoparticles functionalised with Ru–dicarboxybipyridine–trimercaptotriazine: SERS effect and application in plasmonic dye solar cells

A dicarboxybipyridine–trimercaptotriazine ruthenium complex, primarily designed for dye–sensitised solar cells (DSSC), has been successfully employed in the generation of electrostatically stabilised gold colloids, because of its high negative charge and capability of binding to gold nanoparticles via the sulphur groups. Strong SERS enhancements have been obtained for the isolated gold nanoparticles, as monitored by dark field hyperspectral and confocal Raman microscopy. A preliminary design of TiO2 solar cell incorporating the ruthenium dye in association with the gold nanoparticles, has been tested, in the presence of a cobalt complex mediator. The results were considered rather promising, in spite of the slight decay of efficiency in relation to the original dye cell, owing to lixiviation processes and electron recombination effects at the interface.