Porous shape-persistent rylene imine cages with tunable optoelectronic properties and delayed fluorescence.

A simultaneous combination of porosity and tunable optoelectronic properties, common in covalent organic frameworks, is rare in shape-persistent organic cages. Yet, organic cages offer important molecular advantages such as solubility and modularity. Herein, we report the synthesis of a series of chiral imine organic cages with three built-in rylene units by means of dynamic imine chemistry and we investigate their textural and optoelectronic properties. Thereby we demonstrate that the synthesized rylene cages can be reversibly reduced at accessible potentials, absorb from UV up to green light, are porous, and preferentially adsorb CO2 over N2 and CH4 with a good selectivity. In addition, we discovered that the cage incorporating three perylene-3,4:9,10-bis(dicarboximide) units displays an efficient delayed fluorescence. Time-correlated single photon counting and transient absorption spectroscopy measurements suggest that the delayed fluorescence is likely a consequence of a reversible intracage charge-separation event. Rylene cages thus offer a promising platform that allows combining the porosity of processable materials and photochemical phenomena useful in diverse applications such as photocatalysis or energy storage.

Long-lived triplet charge-separated state in naphthalenediimide based donor-acceptor systems.

1,4,5,8-Naphthalenediimides (NDIs) are widely used motifs to design multichromophoric architectures due to their ease of functionalisation, their high oxidative power and the stability of their radical anion. The NDI building block can be incorporated in supramolecular systems by either core or imide functionalization. We report on the charge-transfer dynamics of a series of electron donor-acceptor dyads consisting of a NDI chromophore with one or two donors linked at the axial, imide position. Photo-population of the core-centred π-π* state is followed by ultrafast electron transfer from the electron donor to the NDI. Due to a solvent dependent singlet-triplet equilibrium inherent to the NDI core, both singlet and triplet charge-separated states are populated. We demonstrate that long-lived charge separation in the triplet state can be achieved by controlling the mutual orientation of the donor-acceptor sub-units. By extending this study to a supramolecular NDI-based cage, we also show that the triplet charge-separation yield can be increased by tuning the environment.

Synchronized and asynchronous modulation of seismicity by hydrological loading: A case study in Taiwan.

Delineation of physical factors that contribute to earthquake triggering is a challenging issue in seismology. We analyze hydrological modulation of seismicity in Taiwan using groundwater level data and GNSS time series. In western Taiwan, the seismicity rate reaches peak levels in February to April and drops to its lowest values in July to September, exhibiting a direct correlation with annual water unloading. The elastic hydrological load cycle may be the primary driving mechanism for the observed synchronized modulation of earthquakes, as also evidenced by deep earthquakes in eastern Taiwan. However, shallow earthquakes in eastern Taiwan (<18 km) are anticorrelated with water unloading, which is not well explained by either hydrological loading, fluid transport, or pore pressure changes and suggests other time-dependent processes. The moderate correlation between stacked monthly trends of large historic earthquakes and present-day seismicity implies a modestly higher seismic hazard during the time of low annual hydrological loading.

Photochemistry Meets Porous Organic Cages.

Chemistry of porous organic cages has developed in the past decade as an alternative to the wellknown nanoporous materials based on extended networks, such as metal organic frameworks (MOFs) or covalent organic frameworks (COFs). Unlike these extended polymeric materials, the molecular nature of organic cages offers important advantages, such as solubility of the material in common organic solvents. However, a simultaneous combination of porosity and additional optoelectronic properties, common in MOFs and COFs, is still quite rare. Therefore, porous organic cages are relatively underdeveloped when compared to MOFs and COFs. Here, we highlight the rich possibilities the porous organic cages offer and discuss the recent development where interesting photophysical properties augment the porosity, including our own work.

Unveiling Tatun volcanic plumbing structure induced by post-collisional extension of Taiwan mountain belt.

The Tatun Volcanic Group (TVG) is proximal to the metropolis of Taipei City (population of ca. 7 million) and has long been a major concern due to the potential risks from volcanic activity to the population and critical infrastructure. While the TVG has been previously considered a dormant or extinct volcano, recent evidence suggests a much younger age of the last eruption event (~ 6000 years) and possible existence of a magma reservoir beneath the TVG. However, the location, dimension, and detailed geometry of the magma reservoir and plumbing system remains largely unknown. To examine the TVG volcanic plumbing structure in detail, the local P-wave travel time data and the teleseismic waveform data from a new island-wide Formosa Array Project are combined for a 3D tomographic joint inversion. The new model reveals a magma reservoir with a notable P-wave velocity reduction of 19% (ca. ~ 19% melt fraction) at 8-20 km beneath eastern TVG and with possible northward extension to a shallower depth near where active submarine volcanoes that have been detected. Enhanced tomographic images also reveal sporadic magmatic intrusion/underplating in the lower crust of Husehshan Range and northern Taiwan. These findings suggest an active volcanic plumbing system induced by post-collisional extension associated with the collapse of the orogen.

Vital Signs: Seismology of Icy Ocean Worlds.

Ice-covered ocean worlds possess diverse energy sources and associated mechanisms that are capable of driving significant seismic activity, but to date no measurements of their seismic activity have been obtained. Such investigations could reveal the transport properties and radial structures, with possibilities for locating and characterizing trapped liquids that may host life and yielding critical constraints on redox fluxes and thus on habitability. Modeling efforts have examined seismic sources from tectonic fracturing and impacts. Here, we describe other possible seismic sources, their associations with science questions constraining habitability, and the feasibility of implementing such investigations. We argue, by analogy with the Moon, that detectable seismic activity should occur frequently on tidally flexed ocean worlds. Their ices fracture more easily than rocks and dissipate more tidal energy than the <1 GW of the Moon and Mars. Icy ocean worlds also should create less thermal noise due to their greater distance and consequently smaller diurnal temperature variations. They also lack substantial atmospheres (except in the case of Titan) that would create additional noise. Thus, seismic experiments could be less complex and less susceptible to noise than prior or planned planetary seismology investigations of the Moon or Mars. Key Words: Seismology-Redox-Ocean worlds-Europa-Ice-Hydrothermal. Astrobiology 18, 37-53.

Seismology-based early identification of dam-formation landquake events.

Flooding resulting from the bursting of dams formed by landquake events such as rock avalanches, landslides and debris flows can lead to serious bank erosion and inundation of populated areas near rivers. Seismic waves can be generated by landquake events which can be described as time-dependent forces (unloading/reloading cycles) acting on the Earth. In this study, we conduct inversions of long-period (LP, period ≥20 s) waveforms for the landquake force histories (LFHs) of ten events, which provide quantitative characterization of the initiation, propagation and termination stages of the slope failures. When the results obtained from LP waveforms are analyzed together with high-frequency (HF, 1-3 Hz) seismic signals, we find a relatively strong late-arriving seismic phase (dubbed Dam-forming phase or D-phase) recorded clearly in the HF waveforms at the closest stations, which potentially marks the time when the collapsed masses sliding into river and perhaps even impacting the topographic barrier on the opposite bank. Consequently, our approach to analyzing the LP and HF waveforms developed in this study has a high potential for identifying five dam-forming landquake events (DFLEs) in near real-time using broadband seismic records, which can provide timely warnings of the impending floods to downstream residents.

Volcanology. The Yellowstone magmatic system from the mantle plume to the upper crust.

The Yellowstone supervolcano is one of the largest active continental silicic volcanic fields in the world. An understanding of its properties is key to enhancing our knowledge of volcanic mechanisms and corresponding risk. Using a joint local and teleseismic earthquake P-wave seismic inversion, we revealed a basaltic lower-crustal magma body that provides a magmatic link between the Yellowstone mantle plume and the previously imaged upper-crustal magma reservoir. This lower-crustal magma body has a volume of 46,000 cubic kilometers, ~4.5 times that of the upper-crustal magma reservoir, and contains a melt fraction of ~2%. These estimates are critical to understanding the evolution of bimodal basaltic-rhyolitic volcanism, explaining the magnitude of CO2 discharge, and constraining dynamic models of the magmatic system for volcanic hazard assessment.

Double stranded polymeric ladderphanes with 16-π-electron antiaromatic metallocycle linkers.

Three double stranded polymeric ladderphanes with 16-π-electron antiaromatic metallocycle linkers are synthesised by ring opening metathesis polymerisation of the corresponding bisnorbornene monomers. Scanning tunnelling microscopic (STM) images indicate that these polymers can assemble nicely on a graphite surface to form a highly ordered pattern which has been observed in other ladderphanes with different kinds of aromatic linkers. Little change in (1)H NMR, absorption spectra and electrochemical oxidation potential between these polymers and the corresponding monomers suggest that there would be no interactions between adjacent antiaromatic linkers in these polymeric ladderphanes. Presumably, the distance between two antiaromatic rings in these ladderphanes (5-6 Å) is far too long in comparison with that between two rings in methylene-bridged antiaromatic superphanes (2.5 Å<), where stabilisation is predicted by theoretical calculations.

Comparatively electrochemical studies at different operational temperatures for the effect of layered silicate and spherical silica on the anticorrosion efficiency of PANI nanocomposite coatings.

In this paper, a series of PANI nanocomposites have been successfully prepared by in situ oxidative polymerization. The as-prepared PANI nanocomposites were subsequently characterized by WAXRD patterns and TEM. It should be noted that the nanocomposite coating containing 3 wt-% of organophilic clay loading was found to exhibit an observable enhanced corrosion protection on cold-rolled steel (CRS) electrode at higher operational temperature of 50 degrees C, which was even better than that of uncoated and electrode-coated with PANI or PANI nanocomposites with 3 wt-% of amino-modified silica nanoparticles alone at room temperature of 30 degrees C based on the electrochemical parameter evaluations (e.g., E(corr), R(p), I(corr), R(corr) and impedance). The vapor permeability property at three different operational temperatures of PANI and PANI nanocomposite membranes were investigated by vapor permeability analyzer (VPA). Effect of material composition on the molecular weight, optical properties and surface hydrophobicity of neat PANI and PANI nanocomposite, in the form of membrane and solution, were studied by gel permeation chromatography (GPC), ultraviolet-visible absorption spectra and contact-angle measurements, respectively. Finally, electrical conductivity at three different operational temperatures of PANI and PANI nanocomposite powder-pressed pellets was also investigated through the measurements of standard four-point-probe technique.

Comparative electrochemical studies at different operational temperatures for the effect of nanoclay platelets on the anticorrosion efficiency of organo-soluble polyimide/clay nanocomposite coatings.

A organic soluble polyimide (SPI) prepared from 4,4'-Oxydianiline and 4,4'-(4,4'-Isopropylidenediphenoxy)bis(phthalic anhydride) was mixed with organo-modified montmorillonite (MMT) in N,N-Dimethylacetamide. The organic soluble polyimide-clay nanocomposite (PCN) materials were characterized by Fourier-Transformation infrared (FTIR), spectroscopy, wide-angle X-ray diffraction (WAXRD) patterns and transmission electron microscopy (TEM). It should be noted that the nanocomposite coating containing 3 wt% of clay loading was found to exhibit an observable enhanced corrosion protection on cold-rolled stell (CRS) electrode at higher operational temperature of 50 degrees C, which was even better than that of uncoated and electrode-coated with SPI alone at room temperature of 30 degrees C based on the electrochemical parameter evaluations. In this work, all electrochemical measurements were performed at a double-wall jacketed cell, covered with a glass plate, through which water was circulated from a thermostat to maintain a constant operational temperature of 30, 40 and 50 +/- 0.5 degrees C. Moreover, a series of electrochemical parameters shown in Tafel, Nyquist and Bode plots were all used to evaluate PCN coatings at three different operational temperatures in 5 wt% aqueous NaCl electrolyte. The molecular barrier properties at three different operational temperatures of SPI and PCN membranes were investigated by gas permeability analyzer (GPA) and vapor permeability analyzer (VPA).

Effect of amino-modified silica nanoparticles on the corrosion protection properties of epoxy resin-silica hybrid materials.

In this paper, a series of organic-inorganic hybrid materials consisting of epoxy resin frameworks and dispersed nanoparticles of amino-modified silica (AMS) were successfully prepared. First of all, the AMS nanoparticles were synthesized by carrying out the conventional acid-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) in the presence of (3-aminopropyl)-trimethoxysilane (APTES) molecules. The as-prepared AMS nanoparticles were then characterized by FTIR, 13C-NMR and 29Si-NMR spectroscopy. Subsequently, a series of hybrid materials were prepared by performing in-situ thermal ring-opening polymerization reactions of epoxy resin in the presence of as-prepared AMS nanoparticles and raw silica (RS) particles. The as-prepared epoxy-silica hybrid materials with AMS nanoparticles were found to show better dispersion capability than that of RS particles existed in hybrid materials based on the morphological observation of transmission electron microscopy (TEM). The hybrid materials containing AMS nanoparticles in the form of coating on cold-rolled steel (CRS) were found to be much superior in corrosion protection over those of hybrid materials with RS particles when tested by a series of electrochemical measurements of potentiodynamic and impedance spectroscopy in 5 wt% aqueous NaCI electrolyte. The increase of corrosion protection effect of hybrid coatings may have probably resulted from the enhancement of the adhesion strength of the hybrid coatings on CRS coupons, which may be attributed to the formation of Fe-O-Si covalent bond at the interface of coating/CRS system based on the FTIR-RAS (reflection absorption spectroscopy) studies. The better dispersion capability of AMS nanoparticles in hybrid materials were found to lead more effectively enhanced molecular barrier property, mechanical strength, surface hydrophobicity and optical clarity as compared to that of RS particles, in the form of coating and membrane, based on the measurements of molecular permeability analysis, dynamic mechanical analysis, contact angle measurements and ultraviolet-visible transmission spectra, respectively.