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Relevant academic research and scientific papers

The oligomer approach: An effective strategy to assess phenylene vinylene systems as organic heterogeneous photocatalysts in the degradation of aqueous indigo carmine dye

Four oligo-phenylenevinylenes (OPVs) were synthesized by the Mizoroki-Heck cross-coupling reaction to provide a deeper understanding of the mechanism and fate of phenylenevinylene systems when applied to the heterogeneous photocatalytic degradation of indigo carmine (IC) dye in aqueous media. OPVs displayed visible light absorption near 500 nm and appreciable emission properties. The stability, mechanism, and photodegradation activity of the OPV systems over aqueous indigo carmine were investigated using radical scavengers, a singlet oxygen (1O2) trap, and ESI-IT-MS. It was confirmed that superoxide radical (O2??), 1O2, and direct oxidation are responsible for dye degradation. Hydroxide radical formation, under neutral pH conditions, does not occur, and it was corroborated by the HOMO and LUMO levels of the photocatalysts. Additionally, the use of oxalic acid as an electron sacrificial donor was demonstrated as an effective approach to enhance the OPVs photocatalytic activity. However, a significant decrease in activity during the first three irradiation cycles was observed, indicating that the enhancement in photo- and chemical stability is required for further dye-contaminated water treatment applications.

Oligo p-Phenylenevinylene Derivatives as Electron Transfer Matrices for UV-MALDI

Phenylenevinylene oligomers (PVs) have outstanding photophysical characteristics for applications in the growing field of organic electronics. Yet, PVs are also versatile molecules, the optical and physicochemical properties of which can be tuned by manipulation of their structure. We report the synthesis, photophysical, and MS characterization of eight PV derivatives with potential value as electron transfer (ET) matrices for UV-MALDI. UV-vis analysis show the presence of strong characteristic absorption bands in the UV region and molar absorptivities at 355 nm similar or higher than those of traditional proton (CHCA) and ET (DCTB) MALDI matrices. Most of the PVs exhibit non-radiative quantum yields (φ) above 0.5, indicating favorable thermal decay. Ionization potential values (IP) for PVs, calculated by the Electron Propagator Theory (EPT), range from 6.88 to 7.96 eV, making these oligomers good candidates as matrices for ET ionization. LDI analysis of PVs shows only the presence of radical cations (M+.) in positive ion mode and absence of clusters, adducts, or protonated species; in addition, M+. threshold energies for PVs are lower than for DCTB. We also tested the performance of four selected PVs as ET MALDI matrices for analytes ranging from porphyrins and phthalocyanines to polyaromatic compounds. Two of the four PVs show S/N enhancement of 1961% to 304% in comparison to LDI, and laser energy thresholds from 0.17 μJ to 0.47 μJ compared to 0.58 μJ for DCTB. The use of PV matrices also results in lower LODs (low fmol range) whereas LDI LODs range from pmol to nmol. [Figure not available: see fulltext.].

IN VIVO IMAGING OF MYELINATION

A molecular probe for labeling myelin includes a fluorescent stilbenzene derivative.