Publications by authors named "Fabiano S Santos"
This study describes the synthesis of new carboxylated merocyanine dyes by Knoevenagel condensation between 4-carboxybenzaldehyde and indolium/benzoindolium- and benzothiazolium-based coupling compounds. The condensations were performed in the presence of ammonium acetate, and the products were obtained in good yields after simple purification. These merocyanines exhibit UV-A-to-blue absorption and blue-to-green fluorescence emission, characterized by relatively large Stokes shift values (∼5000 cm).
View Article and Find Full Text PDFHighly Water-Stable Polymer-Perovskite Nanocomposites.
ACS Appl Mater Interfaces
December 2021
The excellent performance of hybrid metal-halide perovskite nanocrystals (NCs) contrasts with their unsatisfactory stability in a high-humidity environment or water. Herein, polymer composite lead-halide perovskites (LHPs) NCs were prepared by casting or spin-coating to produce a high fluorescence yield and a fully water-resistant material. Poly(l-lactide) (PLla), polypropylene glycol (PPGly), and polysulfone (PSU) commercial polymers were used to prepare suspensions of MAPbBr-HDA NCs (MA: CHNH; HDA: hexadecylamine).
View Article and Find Full Text PDFIn this article, new fluorescent lipophilic based benzazoles were synthesized from the reaction between photoactive formyl derivatives and aliphatic amines followed by NaBH4 reduction with good yields. The photophysics of the benzazoles was investigated experimentally and theoretically. These compounds present absorption maxima in the UV region (∼339 nm) and fluorescence emission maxima in the cyan to green region with a large Stokes shift (∼175 nm) due to a proton transfer process in the excited state.
View Article and Find Full Text PDFArticle Synopsis
- The paper discusses the phenomenon of photoinduced electron transfer through an organic molecular wall using octa acid encapsulated ESIPT (Excited State Intramolecular Proton Transfer) dyes as electron donors.
- The study highlights the effects of encapsulation on the efficiency and dynamics of the electron transfer process, which is significant for potential applications in organic electronics and solar energy conversion.
- The authors present experimental findings and theoretical analyses that demonstrate how the molecular environment influences electron transfer, contributing to a deeper understanding of energy transfer mechanisms in organic materials.
Article Synopsis
- Researchers found that certain dyes can transfer electrons efficiently when they're enclosed in a water-soluble structure called octa acid in water.
- The study showed that 4,4′-Dimethylviologen dichloride is the most effective electron acceptor compared to another compound, N-methylpyridinium iodide.
- This effectiveness is likely due to 4,4′-Dimethylviologen's stronger binding to the outer walls of the host octa acid.
Article Synopsis
- The study examines how two flavone derivatives, 3-hydroxyflavone and 4'-N,N-diethylaminoflavonol, behave in excited states when placed in a confined medium.
- It suggests that supramolecular interactions can significantly change the fluorescence characteristics of these compounds.
- In the specific environment of an octa acid host, both dyes exhibit a unique large Stokes shift in their emission due to proton transfer within the molecules, contrasting with their behavior in water.
Two Schiff bases were synthesized by reaction of 2-(4'-aminophenyl)benzoxazole derivatives with 4-N,N-diethylaminobenzaldehyde. UV-visible (UV-vis) and steady-state fluorescence in solution were applied in order to characterize its photophysical behavior. The Schiff bases present absorption in the UV region with fluorescence emission in the blue-green region, with a large Stokes' shift.
View Article and Find Full Text PDFIn this paper, we present a fuzzy approach to the Reed-Frost model for epidemic spreading taking into account uncertainties in the diagnostic of the infection. The heterogeneities in the infected group is based on the clinical signals of the individuals (symptoms, laboratorial exams, medical findings, etc.), which are incorporated into the dynamic of the epidemic.
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