RESUMO
This work describes the synthesis and aggregation behavior of a dimeric bile acid derivative in which two steroid cores are bridged by a p-di(phenylethynyl)phenylene fluorophore. The studied compound contains three key characteristics: (a) restricted conformational equilibrium in solution, (b) efficient fluorescence conferred by the bridge, and (c) medium responsiveness encoded in the steroid fragments. The incorporation of the three components afforded a compound that generates nano- and micrometric spherical particles with aggregation-responsive fluorescence emission. The observed self-assembly process of the featured molecule was induced by the gradual addition of water to the tetrahydrofuran (THF) solution. This aggregation led to significant changes in fluorescence that went from two bands at λem values of 370 and 390 nm in pure THF to a new spectrum with two maxima at λem values of 395 and 418 nm at high water contents, without a decrease in emission. The observed changes can be ascribed to weakly coupled aggregation, a hypothesis supported by multiscale molecular modeling, which sheds light on the mechanism of the self-assembly of this unconventional amphiphile.
Assuntos
Ácidos e Sais Biliares , Polímeros , Modelos Moleculares , Espectrometria de Fluorescência , ÁguaRESUMO
A multicomponent diversity-oriented synthesis of new highly emissive tetracyclic isoquinolines that target specific organelles is described. The title compounds were prepared via a three-step protocol starting with an Ugi four-component reaction, followed by either an intramolecular alkyne hydroarylation and subsequent alkene isomerization or through a Pomeranz-Fritsch-type cyclization with a final intramolecular Heck reaction. Subcellular localization studies of these compounds using green channel confocal microscopy revealed remarkable and distinctive distribution patterns in live cells, showing an unprecedented high selectivity and imaging contrast. The differentiated organelle visualization-including localizers for mitochondria, lysosomes, Golgi apparatus, endoplasmic reticulum, and plasma membrane-was achieved by varying the nature of the tetracyclic system and substituent pattern, changing the original four-component set in the starting Ugi reaction.
Assuntos
Corantes Fluorescentes/química , Isoquinolinas/síntese química , Isoquinolinas/metabolismo , Frações Subcelulares/metabolismo , Células HeLa , Humanos , Isoquinolinas/químicaRESUMO
A new rotor exhibits rich solvatomorphism behavior with eight X-ray structures obtained. A heterogeneous solid obtained by mechanical stress exhibited a dominant isotropic 2H line shape at high temperatures. The motion occurs only in the amorphous component of this solid, with an Ea of 7.4 kcal mol-1 and a low pre-exponential factor A of 6.22 × 1010 s-1, which indicates that the motion requires the distortion of the molecular axis.
RESUMO
The use of the multicomponent Ugi reaction to rapidly prepare a library of dumbbell-like molecular rotors is highlighted here. The synthetic strategy consisted of the atom-economic access to 15 bulky and structurally diverse iodinated stators, which were cross-coupled to the 1,4-diethynylphenylene rotator. From those experiments, up to six rotors 1a-c and 1l-n were obtained, with yields ranging from 35 to 69% per coupled C-C bond. In addition to the framework diversity, five of these compounds showed aggregate-enhanced emission properties thanks to their conjugated 1,4-bis(phenylethynyl)benzene cores, a property that rises by increasing the water fraction (fw) in their THF solutions. The results highlight the significance of the diversity-oriented synthesis of rapid access to new molecular fluorescent rotors.