RESUMO
The fluorescence spectral fingerprint, also known as the excitation-emission matrix (EEM), is used to assess and visualize therapeutic drug photodegradation in combination with chemometrics. Examination of EEM-parallel factor analysis (PARAFAC) data showed that an individual component was easily separated from a mixture of photogenerated products of a heterocyclic pharmacophore, in this case, phenothiazine drugs (PTZs). Detailed investigations of both structure-EEM relationships and kinetics revealed that the components extracted from EEM-PARAFAC could be quantitatively attributed to such photogenerated products as phenothiazine sulfoxide and carbazole derivatives. EEM in combination with principal component analysis (PCA) could be used as a mapping tool to visualize information of the photodegradation process of PTZs. We also assessed the photostability of various types of PTZs containing side chains by using validated EEM-PARAFAC methodology.
RESUMO
Mechanochromic organic molecules (MOMs) that exhibit a large difference of fluorescence wavelength between two states have important potential applications, but few such compounds are known. Here, we report a new MOM, cis-ABPX01(0), which shows switchable near-IR and blue fluorescence responses. Detailed spectrophotometric and single-crystal X-ray analyses revealed that the near-IR fluorescence is attributable to fluorescence from slip-stacked dimeric structures in crystals, while the blue fluorescence is attributable to fluorescence from the monomer. Switching between the two is achieved by dynamic structural interconversion between the two molecular packing arrangements in response to mechanical grinding and solvent vapor-fuming.
Assuntos
Fluoresceínas/química , Xantenos/química , Fluorescência , Raios Infravermelhos , Estrutura MolecularRESUMO
New derivatives of aminobenzopyrano-xanthene (ABPX) dyes have been designed and synthesized with high fluorescence quantum yields in the visible and far-red regions. It was kinetically demonstrated that the structurally rigid conjugation of the xanthene moiety, which is closely related to the reduction of the nonradiative deactivation process, is an effective molecular design for the drastic enhancement of fluorescence emission efficiency.
Assuntos
Benzopiranos/química , Corantes Fluorescentes/síntese química , Xantenos/química , Corantes Fluorescentes/química , Cinética , Estrutura Molecular , Espectrometria de Fluorescência , Espectrofotometria UltravioletaRESUMO
We have designed and synthesized a new class of rhodamine dyes with an extended π-conjugated system and named them 3',3''-bis(oxospiroisobenzofuran)-3,7-bis(diethylamino)benzopyrano-xanthene (ABPX01) dyes. ABPX01 exhibits fluorescence emission in both dilute solution and the aggregate state, whereas conventional rhodamine dyes show aggregation-induced quenching (AIQ). The chemical species of ABPX01 in solution were determined by spectrophotometric measurements and density functional theory (DFT) calculations to study the relationship among chemical species, color, and fluorescence emission. ABPX01 has various forms: the spirolactone form (ABPX01(0)), which is colorless; and the monocationic form (ABPX01H(+)) and the dicationic form (ABPX01H(2)(2+)), which are colored. By orienting a pair of spirolactone benzene moieties differently, the stereoisomers of trans- and cis-ABPX01(0) were separated and their crystal structures determined. ABPX01H(2)(2+) was identified to be a red fluorescent species. Detailed spectroscopic and electron microscopic investigations led to the assumption that the ABPX01H(2)(2+) formed ion associates with Cl(-) as counter anions in HCl aqueous solution, and the nano- and submicrometer-sized colloidal aggregates of ABPX01 hydrochloride exhibit fluorescence emission. To further verify the aggregation-induced emission enhancement (AIEE) mechanism, ABPX01 hydrochloride was synthesized and its fluorescence was similarly checked in the powder state. AIEE in ABPX01 might be attributed to the synergistic combination of the restriction of dye-dye interaction induced dimer formation by sterically hindered ion associates and carboxylic benzene moieties, and the structural rigidity and intermolecular arrangement of the xanthene moiety. We expect that the design strategy of ABPX dyes will be extended to the development of a wide variety of functional organic-dye-based fluorophores (ODFs) with suitable fluorescence-emission controlled mechanisms for many useful applications in new electroluminescent devices.
Assuntos
Benzofuranos/química , Corantes Fluorescentes/química , Xantenos/química , Cristalografia por Raios X , Conformação Molecular , Soluções/química , EstereoisomerismoRESUMO
A new class of rhodamine luminophores, 3',3''-bis(oxospiroisobenzofuran)-3,7-bis(dialkylamino)benzopyrano-xanthene derivatives (ABPX), have been successfully developed. The emission behavior of ABPX series is directly opposite to the concentration quenching of conventional rhodamine dyes. ABPX series exhibit aggregation-induced emission enhancement (AIEE).