Fluorogenic Rhodamine Probes with Pyrrole Substitution Enables STED and Lifetime Imaging of Lysosomes in Live Cells.

Fluorogenic dyes with high brightness, large turn-on ratios, excellent photostability, favorable specificity, low cytotoxicity, and high membrane permeability are essential for high-resolution fluorescence imaging in live cells. In this study, we endowed these desirable properties to a rhodamine derivative by simply replacing the N, N-diethyl group with a pyrrole substituent. The resulting dye, Rh-NH, exhibited doubled Stokes shifts (54 nm) and a red-shift of more than 50 nm in fluorescence spectra compared to Rhodamine B.

Aryl-Modified Pentamethyl Cyanine Dyes at the C2' Position: A Tunable Platform for Activatable Photosensitizers.

Pentamethyl cyanine dyes are promising fluorophores for fluorescence sensing and imaging. However, advanced biomedical applications require enhanced control of their excited-state properties. Herein, a synthetic approach for attaching aryl substituents at the C2' position of the thio-pentamethine cyanine (TCy5) dye structure is reported for the first time.

Ultrafast synthesis of silicone elastomers using silsesquioxane cages as crosslinkers.

Cross-linked siloxane/silsesquioxane-based elastomers were easily prepared in 15 min the anionic ring-opening polymerization of cyclotetrasiloxane (D) and a polyhedral oligomeric silsesquioxane, using KCO as a catalytic base in dimethylformamide at 70 °C. The resulting silicone elastomers have high mechanical strength, good thermal stability, and good superhydrophobic properties.

Ground-state intramolecular proton transfer inhibits the selective methylation on quinoline and pyridine derivatives.

Methylation is one of the crucial steps for drug discovery, organic synthesis, and catalysis. Despite being a versatile and well-known chemical reaction, its chemoselectivity has not been well addressed. In this paper, we reported a thorough experimental and computational investigation of the selective -methylation of N-heterocyclic compounds, mainly quinolines and pyridines.

Stepwise on-demand functionalization of multihydrosilanes enabled by a hydrogen-atom-transfer photocatalyst based on eosin Y.

Organosilanes are of vital importance for modern human society, having found widespread applications in functional materials, organic synthesis, drug discovery and life sciences. However, their preparation remains far from trivial, and on-demand synthesis of heteroleptic substituted silicon reagents is a formidable challenge. The generation of silyl radicals from hydrosilanes via direct hydrogen-atom-transfer (HAT) photocatalysis represents the most atom-, step-, redox- and catalyst-economic pathway for the activation of hydrosilanes.

A Descriptor for Accurate Predictions of Host Molecules Enabling Ultralong Room-Temperature Phosphorescence in Guest Emitters.

Although doping can induce room-temperature phosphorescence (RTP) in heavy-atom free organic systems, it is often challenging to match the host and guest components to achieve efficient intersystem crossing for activating RTP. In this work, we developed a simple descriptor ΔE to predict host molecules for matching the guest RTP emitters, based on the intersystem crossing via higher excited states (ISCHES) mechanism. This descriptor successfully predicted five commercially available host components to pair with naphthalimide (NA) and naphtho[2,3-c]furan-1,3-dione (2,3-NA) emitters with a high accuracy of 83 %.

Lithium-Templated Formation of Polyhedral Oligomeric Silsesquioxanes (POSS).

A coordination complex, lithium hepta(-butyl)silsesquioxane trisilanolate (; Li-T), a stable intermediate in silsesquioxane (SQ) syntheses, was successfully isolated in 65% yield and found to be highly soluble in nonpolar solvents such as hexane. The structure of Li-T was confirmed by NMR, IR spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry, and computational simulation, providing detailed elucidation of the intermolecular self-association of the SQ cage with a box-shaped LiO polyhedron through strong coordination bonds. After acid treatment, Li-T undergoes lithium-proton cationic exchange, yielding hepta(-butyl)silsesquioxane trisilanol (; H-T) quantitatively.

Anion identification using silsesquioxane cages.

Anthracene-conjugated octameric silsesquioxane (AnSQ) cages, prepared Heck coupling between octavinylsilsesquioxane (OVS) and 9-bromoanthracene, thermodynamically display intramolecular excimer emissions. More importantly, these hosts are sensitive to each anionic guest, thereby resulting in change of anthracene excimer formation, displaying the solvent-dependent fluorescence and allowing us to distinguish up to four ions such as F, OH, CN and PO by fluorescence spectroscopy. Depending on the solvent polarity, for example, both F and CN quenched the fluorescence emission intensity in THF, but only F could enhance the fluorescence in all other solvents.

Silsesquioxane cages as fluoride sensors.

Pyrene functionalized silsesquioxane cages (PySQ) not only provide significant fluorescence from pyrene-pyrene excimers with a very large Stokes shift (Δλ = 143 nm, 69 930 cm) in DMSO but also exhibit fluoride capture results coincidentally with a π-π* fluorescence enhancement. On the other hand, PySQ-F in THF significantly exhibits π-π* fluorescence quenching and a color change can be observed with the naked eye from light yellow to deep orange by forming a charge-transfer (CT) complex among the pyrenyl rings. Moreover, PySQ selectively captures F with a response time of <2 min and with a very low detection limit (1.