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The observation and discovery of lysosome dynamic alterations will greatly contribute to the in-depth understanding of lysosome biology and the development of new cancer therapeutics. To visualize lysosomal dynamics, here we have developed a lysosome-targetable fluorescent probe of

Recent work has demonstrated that force-triggered mechanochemical reactions within a polymeric material are capable of inducing measurable changes in macroscopic material properties, but examples of bulk property changes without irreversible changes in shape or structure are rare. Here, we report a double-network hydrogel that undergoes order-of-magnitude increases in acidity when strained, while recovering its initial shape after large deformation. The enabling mechanophore design is a 2-methoxy

We report the mechanochemical reactivity of the highly strained pentacyclic hydrocarbon cubane. The mechanical reactivity of cubane is explored for three regioisomers with 1,2-, 1,3-, and 1,4-substituted pulling attachments. Whereas all compounds can be activated thermally, mechanical activation is observed via pulsed ultrasonication of cubane-containing polymers only when force is applied via 1,2-attachment. The single observed product of the force-coupled reaction is a thermally inaccessible

Longer and stronger; stiff but not brittle Hydrogels are highly water-swollen, cross-linked polymers. Although they can be highly deformed, they tend to be weak, and methods to strengthen or toughen them tend to reduce stretchability. Two papers now report strategies to create tough but deformable hydrogels (see the Perspective by Bosnjak and Silberstein). Wang et al . introduced a toughening mechanism by storing releasable extra chain length in the stiff part of a double-network hydrogel. A high applied force triggered the opening of cycling strands that were only activated at high chain extension. Kim et al . synthesized acrylamide gels in which dense entanglements could be achieved by using unusually low amounts of water, cross-linker, and initiator during the synthesis. This approach improves the mechanical strength in solid form while also improving the wear resistance once swollen as a hydrogel. —MSL

Two large landslides successively blocked the Jinsha River at the same location in Jiangda Village on October 10 and November 3, 2018, respectively. The dynamic processes and possible interactions of the two landslides need to be studied to better understand the physical processes involved, and to provide information on future disaster mitigation. We investigated their force histories and sliding directions by inverting regional broadband seismograms. The scale of the October landslide was approximately three times that of the November event. The October event revealed a particularly strong deceleration force, which may have been caused by a collision between the sliding mass and ground surface. In contrast, the November event had a relatively weaker deceleration force, indicating that it may have been gradually stopped by the landslide dam formed during the October landslide. The sliding directions of the two landslides differed significantly in terms of both horizontal and vertical directions, indicating a change in their sliding surfaces. We conclude that unconsolidated materials at the top of the October landslide continued sliding along a curved slope during the November event. From our seismic models of dynamic processes, both the October landslide and local background may have affected and even changed a subsequent landslide’s mechanism.

The 2019 Ridgecrest, California, earthquake sequence included an Mw 6.4 foreshock on 4 July, followed by an Mw 7.1 mainshock about 32 hr later. We determined the rupture patterns of the foreshock and mainshock by applying the automatic iterative deconvolution and stacking method to strong-motion records. The foreshock was characterized by a unilateral rupture toward the southwest, and the shallow portion had a relatively large slip with the maximum value of ∼1.4 m. The mainshock presents an asymmetrical bilateral rupture with an average rupture velocity of 2.0 km/s. More than 80% of the seismic moment was released on the northwest segment of the fault, producing a maximum slip of ∼5.2 m. With the two inferred slip models, we calculated the Coulomb failure stress change (ΔCFS) to analyze the spatial–temporal correlation of the seismicity activity in this sequence. The result shows that the epicenter of the Mw 7.1 mainshock was brought 0.4 bars closer to failure by the Mw 6.4 foreshock, and the stress-increased zone has a good spatial consistence with the coseismic slip distribution of the mainshock and the aftershock distribution of the foreshock. Besides, the positive ΔCFS induced by the mainshock also enhanced its aftershock activity, especially at depths of 4–10 km where the major rupture occurred, inferring that the mainshock-induced ΔCFS may be responsible for the occurrence of aftershocks. In addition, we test the effects of different cutoff frequencies and crust velocity structures on the inversion results. The result reveals that the main source rupture characteristics are almost independent of these factors, implying a high reliability of automation inversion of strong-motion data. Overall, this work indicates that automatic inversion of strong-motion data can provide reliable and rapid rupture model, which is essential for earthquake emergency responses and tsunami early warnings.

Currently, the majority of ultralong organic luminescence (UOL) materials show an undiversified color of yellow with a vibrational-structured spectrum [λUOL: ∼550 nm; shoulders: ∼600 and ∼650 nm]. Herein, we demonstrate that the radiative deactivation of singlet and/or triplet excitons showing an intermolecular through-space charge-transfer (I-TSCT) character can also result in UOL. With the aid of their CT feature of the long-lived excited state, the emission color of UOL materials based on this mechanism can be fine-tuned rationally. Using this constructive strategy, compounds CzSO and β-CbSO with λUOL of 490 nm and 460 nm, respectively, have been acquired successfully. Note that the UOL of CzSO has a long lifetime of 0.45 s together with a quantum efficiency over 26% under visible-light excitation at 440 nm. Moreover, thanks to its ground-state CT character, bright two-photon excited UOL is also observed in crystalline CzSO under near-infrared (NIR) excitation at 840 nm.

Aiming for solving the emergence of drug-resistant bacteria worldwide, the construction of novel supramolecular self-assembly systems with antibacterial functions is attracting growing research attention. Herein, using dynamically reversible Schiff-base imine bonds as the assembly strategy, a three-dimensional pure organic cage, namely 4-cage, was obtained in high yield. By taking advantage of the bidentate chelating capability of its imine-based skeleton, 4-cage was demonstrated to serve as an Ag+-carrier. Owing to the acid-induced decomposition of this skeleton, the Ag+-loaded 4-cage can controllably release Ag+ through pH regulation, hence, as a proof-of-concept, it is proved to be applicable as a controllable release antibacterial reagent. Such pH-responsive Ag+-carried supramolecular architecture may shed light on the molecule design strategies for bacterial elimination in different environments, or for controllable functions in various other fields.

After entering a cell, most small molecule fluorescent probes are dispersed in the cytoplasm before they then accumulate in a specific organelle or subcellular zone. Molecules that can enter two or more organelles with high selectivity are all but unknown. In this work, we report a naphthalimide-based fluorescent probe, NIM-7, that allows lipid droplets and lysosomes to be labelled simultaneously and with high specificity. These subcellular entities can then be visualized readily through yellow and red fluorescence, using different excitation and detection channels. NIM-7 allows 3D imaging and quantitative visualizing of lipid droplets and lysosomes. It is also able to track simultaneously the movement of lipid droplets and lysosomes in real-time. We also report here that NIM-7 can be used to image both different cell lines and zebrafish embryos.

A bistable [2]catenane composed of a tetracationic cyclophane, namely cyclobis(paraquat-p-phenylene) (CBPQT4+) that is mechanically interlocked by a neutral macrocylic component containing both a 1,5-dioxynaphthalene (DNP) and a naphthalene-1,4,5,8-bis(dicarboximide) (NDI) unit, was obtained by using template-directed synthesis via click chemistry. In the fully oxidized state, the CBPQT4+ component encircles the DNP unit, driven by donor-acceptor interactions. Upon reduction of both the CBPQT4+ ring and the NDI unit, the CBPQT2(˙+) ring undergoes shuttling and resides on the NDI˙- station, driven by coulombic-enhanced spin-pairing interactions between different aromatic radicals.

Automatic and rapid imaging of earthquake rupture process is a difficult task but critical for postearthquake response and possible tsunami early warning. We have developed an automatic system for finite‐fault inversion based on the iterative deconvolution and stacking (IDS) approach, in which we screen the waveforms and update the fault size automatically. Strong‐motion seismograms are used in offline tests to invert for the rupture processes of 34 significant earthquakes in 2008–2017 in and around Japan with magnitudes MW ≥ 6.0 occurred onshore and MW ≥ 6.5 offshore. Rupture model of an earthquake, including moment magnitude, source time function, slip distribution, rupture velocity, and stress drop, is obtained in ~1.5 min on a desktop PC. The moment magnitudes we obtained are consistent with those published by other agencies. The slip distributions, rupture directions, and velocities also agree well with those released by the Japan Meteorological Agency. In all test cases, our results show that the automatic inversion of strong‐motion data can provide reliable major source parameters without manual revision, which demonstrates great potential for emergency response and tsunami early warning purposes. The automatic inversion system developed in this work can also be used to build catalogs of finite‐fault models for moderate to strong earthquakes in other areas where the moment tensor solutions and near‐field waveform data are available.

A macrocycle through a dynamic covalent approach relying on reversible hydrazone formation in acidic aqueous solutions at elevated temperatures is constructed. By decreasing the acidity of the solution and lowering the temperature, the structure becomes kinetically inert. The macrocycle is capable of hosting hydrophobic aromatic guest molecules in water.

Serving as important dynamic cytoplasmic organelles in cells, lipid droplets (LDs) play indispensable roles in membrane formation, intracellular signaling and energy supply for cellular functions. Hence, clear and selective probing and tracking of LDs to study their biological functions are of great interests in recent years. In this work, we synthesized and developed NIM-3A, a novel and highly selective fluorescent bioprobe for super-resolution imaging of LDs in living cells, which further allows us to quantitatively measure the number and diameter of LDs in a single living cell. Moreover, NIM-3A can also provide a reliable platform to monitor the dynamic movement of LDs, which further expands its potential applications in the cell biology of lipid droplets.

Lysosomes function as important organelles within cells and their movement associates with diverse biological events, hence the real-time tracking of lysosomal movement is of great significance. However, since most lysosome fluorescent probes suffer from relatively unsatisfactory photostability, tracking lysosomal movement in real-time remains challenging. Here, we report that a naphthalimide-based fluorescent compound, namely NIMS, is a quite promising probe for lysosome imaging. The visualizing mechanism lies in the selective accumulation of NIMS in lysosomes via a protonation reaction, followed by the fluorescence enhancement due to the interactions of NIMS with proteins. Owing to its high selectivity and good photostability, NIMS was successfully applied to capture super-resolution fluorescence images of lysosomes. More importantly, real-time tracking of lysosome movement in a single living cell by NIMS was realized with a confocal laser scanning microscope. Surprisingly, even in normal culture conditions, around 2/3 of the captured lysosomes were observed to move within 5 min, indicative of the highly dynamic features of lysosomes. Thus, this probe may facilitate the understanding of the lysosome dynamics in physiological or pathological conditions.

The application of fluorescent probes for organelle imaging and tracking has been extensively explored in recent years due to their unique optical performance. This review focuses on 1,8-naphthalimide (NI) fluorophore highlighting the recent advances in imaging and tracking of individual or multiple organelles in living cells. Specifically, we emphasize their labeling mechanism, and summarize the applications by monitoring their dynamic microenvironment (e.g., viscosity, polarity, temperature, and pH), bioactive species (e.g., cations/anions, molecules, radicals), and the enzyme activities. We also point out the shortcomings of the reported NI-based organelle fluorescent probes and present our perspective on the future developments in this field. We hope this review can be used not only as a reference for beginners, but also as a compass of these fields, and contribute to solving more promising and meaningful topics for chemical and biological researchers.

A novel naphthalimide-based fluorescent sensor, namely NIMS , is designed and synthesized for fluoride ion detection. NIMS undergoes a desilylation reaction upon addition of F − ion, thereby shows a colorimetric/fluorometric dual-channel spectral response, i.e. , a huge ratiometric absorption value of 229 nm together with distinct colour change from yellow to blue, and drastically quenched fluorescence as well. Additionally, NIMS shows high selectivity, good sensitivity and rapid response toward F − ion, and could be used in qualitative detection of F − ion in the solid state and quantitative detection F − ion in toothpaste samples.

We demonstrated that a purely organic stack, namely, TPE-3-stack, can be assembled in high yield by using dynamic imine chemistry. TPE-3-stack emits strong fluorescence not only in the solid state (ϕPL = 83%) but also in dilute solutions (e.g., ϕPL = 82% in DMSO), which is significantly distinct from the case of the aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE) chromophores. In addition, it shows high spectral, thermal, and chemical stabilities as well as excellent solubility in common solvents. Therefore, this stack is feasible for fabricating a solution-processed electroluminescent device, which displays brightness over 1000 cd m-2 and a current efficiency up to 2.3 cd A-1. TPE-3-stack is also demonstrated as a promising fluorescent visualizer for lysosome imaging. Such characteristics of the stack compound were attributed to the efficient suppression of intramolecular rotation and vibration by locking its structure into the rigid framework by means of a self-assembly strategy.

Owing to the quite similar chemical properties of H

The performance enhancement of organic optoelectronic integrated device (OID) was realized by using a triplet-triplet annihilation (TTA) featured material of 6-(3,5-bis-[9-(4- t -butylphenyl)-9 H -carbazol-3-yl]-phenoxy}-2-(4- t -butylphenyl)-1 H -benzo[ de ]isoquinoline-1,3(2 H )-dione (CzPhONI) as a host and another TTA featured material of ( E )-2-[4-( t -butyl)phenyl]-6-{2-[6-(diphenylamino)naphthalene-2-yl] vinyl}-1 H -benzo [ de ]isoquinoline-1,3(2 H )-dione (NA-TNA) as a dopant in a doping system to be an active layer. The result showed that the OID with a doping system had a maximum luminance of 7100 cd/m 2 with a lower turn-on voltage of 2.5 V as OLED. Meanwhile, the NA-TNA doped OID exhibited a high detectivity of 4.5 × 10 12 Jones at a bias of −1 V under the UV-350 nm illumination, which was 34.6 folds higher than that of the pristine CzPhONI based device. Based on the analysis of the energy transfer model of devices, it was found that the improved electroluminescent performance of OID was attributed to the TTA process and efficient energy transfer from CzPhONI to NA-TNA. And by analyzing the dark current behavior of device, the high ultraviolet detective property of OID was caused by the merit of the energy band “carrier capture region” when the dopant NA-TNA was added into the active layer, and the energy band “carrier capture region” contributed to reducing the dark current of OID.

Owing to the difficulty in acquiring compounds with combined high energy bandgaps and lower-lying intramolecular charge-transfer excited states, the development of ultraviolet (UV) thermally activated delayed fluorescence (TADF) materials is quite challenging. Herein, through interlocking of the diphenylsulfone (PS) acceptor unit of a reported deep-blue TADF emitter (CZ-PS) by a dimethylmethylene bridge, CZ-MPS, a UV-emissive TADF compound bearing a shallower LUMO energy level and a more rigid structure than those of CZ-PS is achieved. This represents the first example of a UV-emissive TADF compound. Organic light-emitting diode (OLED) using CZ-MPS as the guest material can emit efficient UV light with emission maximum of 389 nm and maximum total external quantum efficiency (EQEmax ) of 9.3%. Note that this EQEmax value is twice as high as the current record EQEmax (4.6%) for UV-OLEDs. This finding may shed light on the molecular design strategy for high-performance UV-OLED materials.

Although numerous thermally activated delayed fluorescence (TADF) organic light‐emitting diodes (OLEDs) have been demonstrated, efficient blue or even sky‐blue TADF‐based nondoped solution‐processed devices are still very rare. Herein, through‐space charge transfer (TSCT) and through‐bond charge transfer (TBCT) effects are skillfully incorporated, as well as the multi‐(donor/acceptor) characteristic, into one molecule. The former allows this material to show small singlet–triplet energy splitting (ΔE ST) and a high transition dipole moment. The latter, on the one hand, further lights up multichannel reverse intersystem crossing (RISC) to increase triplet exciton utilization via degenerating molecular orbitals. On the other hand, the nature of the molecular twisted structure effectively suppresses intermolecular packing to obtain high photoluminescence quantum yield (PLQY) in neat flims. Consequently, using this design strategy, T‐CNDF‐T‐tCz containing three donor and three acceptor units, successfully realizes a small ΔE ST (≈0.03 eV) and a high PLQY (≈0.76) at the same time; hence the nondoped solution‐processed sky‐blue TADF‐OLED displays record‐breaking efficiency among the solution process‐based nondoped sky‐blue OLEDs, with high brightness over 5200 cd m−2 and external quantum efficiency up to 21.0%., A novel multi‐(donor/acceptor) thermally activated delayed fluorescence (TADF) molecule with through‐space/‐bond charge transfer is developed. Its nondoped solution‐processed sky‐blue organic light‐emitting diode (OLED) displays high performance with an external quantum efficiency (EQEmax) up to 21.0%, which represents the record‐breaking efficiency among the solution process‐based nondoped sky‐blue OLEDs.

By condensing a trisamino linker with one of the two analogous bisaldehyde ligands, pills and tetrahedrons could be self-assembled. The self-assembled preference could be controlled by tuning the reaction conditions, including the size of side chain, concentration, and temperature. Coordination of silver cation quenches the fluorescence of the fluorene moieties on the pill, opening up opportunities for Ag+ cation detection.

Using a novel dynamic covalent approach relying on reversible hydrazone formation, a purely organic 3-dimensional prismatic cage was developed in water at elevated temperatures. By lowering the temperature, the hydrazone bond becomes kinetically inert. This self-assembled cage acts as an effective receptor for donor–acceptor pairs, whose interactions are weak in the absence of the cage.

A red naphthalimide derivative with an intramolecular charge-transfer (ICT) feature, namely (E)-2-(4-(t-butyl)phenyl)-6-(2-(6-(diphenylamino)naphthalen-2-yl)vinyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (NA-TNA), was designed and synthesized. Photophysical and magneto-electroluminescence (MEL) characterization results revealed that NA-TNA could harvest triplet excitons via a triplet–triplet annihilation (TTA) process in organic light-emitting diodes (OLEDs) due to the presence of a lower-lying triplet excited state with 3ππ* character. Consequently, using NA-TNA as a guest compound and CzPhONI, another ICT-featured naphthalimide derivative with triplet fusion delayed fluorescence (TFDF) character as host material, a high-performance orange OLED with 6 wt% NA-TNA doped CzPhONI film as the emitting layer was acquired. The maximum current efficiency (LEmax), brightness (Lmax), and external quantum yield (EQEmax) of this OLED is 7.73 cd A−1, 31 940 cd m−2 and 5.83%, respectively, while the theoretical EQEmax of this device should not exceed 3.34%. On the contrary, the reference device with a NA-TNA doping level of 1.4 wt% showed much inferior performance, with a LEmax, a Lmax, and an EQEmax of 3.19 cd A−1, 24 900 cd m−2 and 2.49%, respectively. The high performance of the 6 wt% NA-TNA doped device was attributed to the efficient harvesting of triplet excitons by both the guest and host materials.

A red aggregation-emission-enhancement guest fluorophor and a green host compound both based upon the naphthalimide skeleton namely, 11- tert -butyl-(( E )-4-(2-(7-(diphenylamino)-9,9-diethyl-9 H -fluoren-2-yl)vinyl)-7 H -benzimidazo[2,1- a ]benzo[ de ]isoquinolin-7-one and 2-(4- tert -butylphenyl)-6-(9-(4- te rt-butylphenyl)-9 H -carbazol-3-yl)-1 H -benzo[ de ]isoquinoline-1,3(2 H )-dione, have been synthesized. They form an efficient energy transfer pair due to their structural similarity. As a consequence of the aggregation characteristics of the red guest, and the high energy-transfer efficiency between the host and guest as well, the 6 wt% heavily-doped organic light-emitting diode based on these naphthalimides shows high performance, with maximum brightness of 6250 cd m −2 and current efficiency of 3.13 cd A −1 . In contrast, the reference device using tris(8-hydroxyquinolinato)aluminium (III) as host just exhibits peak luminance of 1160 cd m −2 and current efficiency of 0.75 cd A −1 . The drastically enhanced device performance was attributed to the much better energy transfer efficiency between the host and guest, which stems from their good structural similarity.

A dual-channel naphthalimide-based chemosensor for rapid and sensitive detection of fluoride ion has been developed. Upon addition of F(-), it undergoes deprotonation reaction through H-bonding interactions, and its maximum absorption wavelength is red-shifted for 214 nm to the far-red region, together with drastically quenched fluorescence. In addition, it shows high selectivity toward F(-) anion, thus could be used for practical applications to detecting F(-) in both solution and solid state. Furthermore, the fluorescence of NIM could be enhanced in protein-containing acidic environments, hence NIM could act as lysosome marker to differentiate cancer cells from normal ones in cell imaging.

In the title compound, C(38)H(42)N(4)O(4)·C(2)H(6)O, prepared via a spiro-lactam ring-formation reaction in a rhodamine dye, the xanthene ring system is approximately planar (r.m.s. deviation = 0.0014Å) and subtends dihedral angles of 88.10 (3) and 86.92 (4)° with the spiro-lactam (r.m.s. deviations = 0.0012 Å) and benzene rings, respectively. The crystal structure consists of chains parallel to [-101], formed via O-H⋯O inter-actions.

In the title compound, C(37)H(40)N(4)O(2), the xanthene and spiro-lactam rings are almost planar, with r.m.s. deviations from the mean planes of 0.223 (2) and 0.057 (2) Å, respectively, and form a dihedral angle of 85.76 (3)°. The dihedral angle between the xanthene mean plane and the benzene ring is 87.16 (5)°. One of the two ethyl groups of one of the diethyl-amino groups is disordered over two sets of sites [0.76 (1):0.24 (1)].