Low-Loss Optical Waveguide and Highly Polarized Emission in a Uniaxially Oriented Molecular Crystal Based on 9,10-Distyrylanthracene Derivatives

A uniaxially oriented crystal based on 9,10-bis­(2,2-di-<i>p</i>-tolylvinyl)­anthracene (BDTVA) with an excellent waveguide and polarization performance has been prepared. The low loss coefficient (2.75 cm^–1) and the high polarization contrast (0.72) may result from the uniaxially oriented packing and layer-by-layer molecular structure in the BDTVA crystal. Moreover, amplified spontaneous emission is observed from the BDTVA crystal with a low threshold of 265 μJ/cm², and the gain coefficient is 52 cm^–1 at the peak wavelength of 509 nm. These features indicate that the BDTVA crystal may be potentially applied in the field of optical waveguides and organic solid-state lasers

Direct Observation of the Symmetrical and Asymmetrical Protonation States in Molecular Crystals

The symmetrical and asymmetrical protonation states are realized via the formation of intermolecular hydrogen bonds inside 9,10-bis­((<i>E</i>)-2-(pyridin-4-yl)­vinyl)­anthracene (BP4VA) molecular crystals. With the protonation of H₂SO₄, BP4VA molecules are protonated symmetrically, while the molecules are asymmetrically protonated by introducing HCl. The different protonation states of BP4VA crystals result in various supramolecular interactions, aggregation states, and even tunable optical properties. It provides a fundamental principle to understand the effect of protonation in organic conjugated molecules and an approach to expanding the scope of organic functional materials

Supramolecular Hybrids of AIEgen with Carbon Dots for Noninvasive Long-Term Bioimaging

Fluorescent bioprobes have been regarded as promising tools for bioimaging in recent years due to their excellent properties. However, the aggregation-caused quenching of emissions is a big limitation in practice for this strategy. Organic dyes with aggregation-induced emission (AIE) feature can effectively solve this problem. Herein, stable fluorescent nanoparticles were prepared by supramolecular assembling of carbon dots (CDs) and hydrophobic AIEgen. The formulated CDsG-AIE 1 exhibits superior physical and photo stability than AIE self-assembling nanoparticles in various physiology conditions. On the other hand, the formulated CDsG-AIE 1 also showed advanced features such as large Stokes shift, good biocompatibility, high emission efficiency, and strong photobleaching resistance. More importantly, the CDsG-AIE 1 can be readily internalized by HeLa cells, and strong red fluorescence from the nanoparticles can still be clearly observed after six generations over 15 days. In addition, the CDsG-AIE 1 also exhibits superior long-term imaging ability in vivo. These incredible features make the AIE nanoparticles to be an ideal fluorescent probe for noninvasive long-term tracing and imaging applications. This work highlights the potential of using carbon dots to assemble AIEgen for the preparation of nanoscale AIEgen-contained particles for desirable bioimaging and diagnostic

Direct Observation of the Symmetrical and Asymmetrical Protonation States in Molecular Crystals

The symmetrical and asymmetrical protonation states are realized via the formation of intermolecular hydrogen bonds inside 9,10-bis­((<i>E</i>)-2-(pyridin-4-yl)­vinyl)­anthracene (BP4VA) molecular crystals. With the protonation of H₂SO₄, BP4VA molecules are protonated symmetrically, while the molecules are asymmetrically protonated by introducing HCl. The different protonation states of BP4VA crystals result in various supramolecular interactions, aggregation states, and even tunable optical properties. It provides a fundamental principle to understand the effect of protonation in organic conjugated molecules and an approach to expanding the scope of organic functional materials

Mechanochromism and Polymorphism-Dependent Emission of Tetrakis(4-(dimethylamino)phenyl)ethylene

The mechanochromic property of tetrakis­(4-(dimethylamino)­phenyl)­ethylene (TDMAPE) with natural propeller shape and nearly centrosymmetric structure was investigated. The destruction of the crystalline structure leads to the planarization of molecular conformation, which is considered as a possible reason for the red-shift of absorption and fluorescence spectra after grinding. And the polymorphism-dependent emissions of the two polymorphs of TDMAPE are mainly determined by the intramolecular conformation, which show the increased coplanarity or conjugation degree, ultimately leading to the bathochromic shift of the emissions

Mechanochromism and Polymorphism-Dependent Emission of Tetrakis(4-(dimethylamino)phenyl)ethylene

The mechanochromic property of tetrakis­(4-(dimethylamino)­phenyl)­ethylene (TDMAPE) with natural propeller shape and nearly centrosymmetric structure was investigated. The destruction of the crystalline structure leads to the planarization of molecular conformation, which is considered as a possible reason for the red-shift of absorption and fluorescence spectra after grinding. And the polymorphism-dependent emissions of the two polymorphs of TDMAPE are mainly determined by the intramolecular conformation, which show the increased coplanarity or conjugation degree, ultimately leading to the bathochromic shift of the emissions

Predicted Formation of H₃⁺ in Solid Halogen Polyhydrides at High Pressures

The structures of compressed halogen polyhydrides H_<i>n</i>X (X = F, Cl and <i>n</i> > 1) and their evolution under pressure are studied using <i>ab initio</i> calculation based on density functional theory. H_<i>n</i>F (<i>n</i> > 1) are metastable up to 300 GPa, whereas for H_<i>n</i>Cl (<i>n</i> > 1), four new stoichiometries (H₂Cl, H₃Cl, H₅Cl, and H₇Cl) are predicted to be stable at high pressures. Interestingly, triangular H₃⁺ species are unexpectedly found in stoichiometries H₂F with [H₃]⁺[HF₂]⁻, H₃F with [H₃]⁺[F]⁻, H₅F with [H₃]⁺[HF₂]⁻[H₂]₃, and H₅Cl with [H₃]⁺[Cl]⁻[H₂] above 100 GPa. Importantly, formation processes of H₃⁺ species are clearly seen on the basis of comparing bond lengths, bond overlap populations, electron localization functions, and Bader charges as a functions of pressure. Further analysis reveals that the formation of H₃⁺ species is attributed to the pressure-induced charge transfer from hydrogen atoms to halogen atoms

Mechanochromism and Polymorphism-Dependent Emission of Tetrakis(4-(dimethylamino)phenyl)ethylene

The mechanochromic property of tetrakis­(4-(dimethylamino)­phenyl)­ethylene (TDMAPE) with natural propeller shape and nearly centrosymmetric structure was investigated. The destruction of the crystalline structure leads to the planarization of molecular conformation, which is considered as a possible reason for the red-shift of absorption and fluorescence spectra after grinding. And the polymorphism-dependent emissions of the two polymorphs of TDMAPE are mainly determined by the intramolecular conformation, which show the increased coplanarity or conjugation degree, ultimately leading to the bathochromic shift of the emissions

Proton-Triggered Hypsochromic Luminescence in 1,1′-(2,5-Distyryl-1,4-phenylene) Dipiperidine

A proton-triggered hypsochromic luminescent chromophore 1,1′-(2,5-distyryl-1,4-phenylene) dipiperidine (DPD) was designed and synthesized. Upon treatment by hydrochloric acid (HCl), the emission of DPD showed a large hypsochromic shift in both THF solution and microcrystals. Theoretical calculations and powder X-ray diffraction experiments reveal that the switchable emission of DPD originated from the change of the distribution and the spatial arrangement of the frontier molecular orbitals, and the different stacking modes of DPD in microcrystals also contribute to the switchable emission of DPD in aggregates

Fluorescent Aptasensor Based on Aggregation-Induced Emission Probe and Graphene Oxide

Recently, a great variety of aggregation-induced emission (AIE)-active molecules has been utilized to design bioprobes for label-free fluorescent turn-on aptasensing with high sensitivity. However, due to nonspecific binding interaction between aptamer and AIE probe, these AIE-based aptasensors have nearly no selectivity, thereby significantly limiting the development. In this work, a 9,10-distyrylanthracene with two ammonium groups (DSAI) is synthesized as a novel AIE probe, and the fluorescent aptasensor based on DSAI and graphene oxide (GO) is developed for selective and sensitive sensing of targeted DNA and thrombin protein. Given its AIE property and high selectivity and sensitivity, this aptasensor can be also exploited to detect other targets