Molecular Sieving of Propyne/Propylene by a Scalable Nanoporous Crystal with Confined Rotational Shutters.

Soft porous coordination polymers (PCPs) have the remarkable ability to recognize similar molecules as a result of their structural dynamics. However, their guest-induced gate-opening behaviors often lead to issues with selectivity and separation efficiency, as co-adsorption is nearly unavoidable. Herein, we report a strategy of a confined-rotational shutter, in which the rotation of pyridyl rings within the confined nanospace of a halogen-bonded coordination framework (NTU-88) creates a maximum aperture of 4.4 Å, which is very close to the molecular size of propyne (C3 H4 : 4.4 Å), but smaller than that of propylene (C3 H6 : 5.4 Å). This has been evidenced by crystallographic analyses and modelling calculations. The NTU-88o (open phase of activated NTU-88) demonstrates dedicated C3 H4 adsorption, and thereby leads to a sieving separation of C3 H4 /C3 H6 under ambient conditions. The integrated nature of high uptake ratio, considerable capacity, scalable synthesis, and good stability make NTU-88 a promising candidate for the feasible removal of C3 H4 from C3 H4 /C3 H6 mixtures. In principle, this strategy holds high potential for extension to soft families, making it a powerful tool for optimizing materials that can tackle challenging separations with no co-adsorption, while retaining the crucial aspect of high capacity.

Identifying high-grade serous ovarian carcinoma-specific extracellular vesicles by polyketone-coated nanowires.

Cancer cell-derived extracellular vesicles (EVs) have unique protein profiles, making them promising targets as disease biomarkers. High-grade serous ovarian carcinoma (HGSOC) is the deadly subtype of epithelial ovarian cancer, and we aimed to identify HGSOC-specific membrane proteins. Small EVs (sEVs) and medium/large EVs (m/lEVs) from cell lines or patient serum and ascites were analyzed by LC-MS/MS, revealing that both EV subtypes had unique proteomic characteristics. Multivalidation steps identified FRα, Claudin-3, and TACSTD2 as HGSOC-specific sEV proteins, but m/lEV-associated candidates were not identified. In addition, for using a simple-to-use microfluidic device for EV isolation, polyketone-coated nanowires (pNWs) were developed, which efficiently purify sEVs from biofluids. Multiplexed array assays of sEVs isolated by pNW showed specific detectability in cancer patients and predicted clinical status. In summary, the HGSOC-specific marker detection by pNW are a promising platform as clinical biomarkers, and these insights provide detailed proteomic aspects of diverse EVs in HGSOC patients.

Quasi-Reversible Photoinduced Displacement of Aromatic Ligands from Semiconductor Nanocrystals.

Organic-inorganic nanohybrids using semiconductor nanocrystals (NCs) coordinated with aromatic organic molecules have been widely studied in the fields of optoelectronic materials, such as solar cells, photocatalysis, and photon upconversion. In these materials, coordination bonds of ligand molecules are usually assumed to be stable during optical processes. However, this assumption is not always valid. In this study, we demonstrate that the coordination bonds between ligand molecules and NCs by carboxyl groups are displaced quasi-reversibly by light irradiation using zinc sulfide (ZnS) NCs coordinated with perylenebisimide (PBI) as a model system. Time-resolved spectroscopy over a wide range of time from tens-of femtosecond to second timescales and density functional theory calculations show that the photoinduced ligand displacement is driven by ultrafast hole transfer from PBI to ZnS NCs and that the dissociated radical anion of PBI survives over the second timescale. Photoinduced ligand displacements are important to be considered in various organic-inorganic nanohybrids and offer a possibility of NCs covered by nonphotoresponsive organic ligands for advanced photofunctional materials.

Anomalously supercooled H2-D2 mixtures flowing inside a carbon nano tube.

H2 and D2 molecules condensed in a carbon nano tube (CNT) and their nonequilibrium flow through nano pores offer a key test to reveal mass molecular transport and separation of purely isotopic molecules that possess the same electronic potential but a two-times difference in mass inducing differently enhanced nuclear quantum effects (NQEs) such as nuclear delocalization and zero-point energy. Taking advantage of the non-empirical quantum molecular dynamics method developed for condensed H2-D2 molecules that can describe various kinds of condensed phases and thermodynamic states including uneven density and a shear flow, we investigated condensed isotopic H2-D2 mixtures flowing inside nanoscale adsorbable CNTs. We found that, in any mixture, the more delocalized H2 molecules are more supercooled than the less delocalized D2 molecules in a two-dimensional liquid film adsorbed around the CNT well, and that the stronger supercooling of the H2 molecules than the D2 molecules in an equilibrium state becomes more enhanced under the nonequilibrium flow due to the isotope-dependent flow-induced condensation, demonstrating the anomalous condensed-phase quantum sieving under the nonequilibrium flow and its dependence on the mixing ratio and temperature. The differently enhanced NQEs of the purely isotopic molecules essentially influence the condensed adsorption and their flows occurring in the nanoscale CNT, which should be distinguished from a dilute gas adsorption. The predicted properties and obtained physical insights in this paper will help in experimentally controlling condensed H2-D2 mixtures, and open a new strategy and innovative design of nanoporous materials for adsorptive separation of condensed-phase mixtures under a nonequilibrium flow not of a dilute gas mixture in an equilibrium state.

Polyoxocationic antimony oxide cluster with acidic protons.

The success and continued expansion of research on metal-oxo clusters owe largely to their structural richness and wide range of functions. However, while most of them known to date are negatively charged polyoxometalates, there is only a handful of cationic ones, much less functional ones. Here, we show an all-inorganic hydroxyiodide [H10.7Sb32.1O44][H2.1Sb2.1I8O6][Sb0.76I6]2·25H2O (HSbOI), forming a face-centered cubic structure with cationic Sb32O44 clusters and two types of anionic clusters in its interstitial spaces. Although it is submicrometer in size, electron diffraction tomography of HSbOI allowed the construction of the initial structural model, followed by powder Rietveld refinement to reach the final structure. The cationic cluster is characterized by the presence of acidic protons on its surface due to substantial Sb3+ deficiencies, which enables HSbOI to serve as an excellent solid acid catalyst. These results open up a frontier for the exploration and functionalization of cationic metal-oxo clusters containing heavy main group elements.

Flow-Induced Autonomic Ordering of Hydrogen Molecules under a Non-Equilibrium Flow.

A non-equilibrium molecular flow through a carbon nanotube (CNT) serves as a key system for revealing molecular transport and establishing nanofluidics. It has been challenging to simulate a non-equilibrium flow of hydrogen molecules exhibiting strong nuclear quantumness. Taking advantage of the quantum molecular dynamics method that can calculate real-time trajectories of hydrogen molecules even under a non-equilibrium flow, we found that the non-equilibrium flow makes hydrogen molecules more condensed and accelerates their adsorption near a CNT surface, letting the molecules flow more smoothly by propagating velocity momenta more efficiently along the CNT axis and by suppressing transverse molecular dynamics on the CNT cross section. Such flow-induced autonomic ordering indicates the importance of monitoring and investigating dynamics and adsorption of hydrogen molecules under a non-equilibrium circumstance as well as in a quiet equilibrium state, opening a new strategy for efficient hydrogen liquefaction and storage.

Real-time hydrogen molecular dynamics satisfying the nuclear spin statistics of a quantum rotor.

Apparent presence of the nuclear-spin species of a hydrogen molecule, para-hydrogen and ortho-hydrogen, associated with the quantum rotation is a manifestation of the nuclear quantum nature of hydrogen, governing not only molecular structures but also physical and chemical properties of hydrogen molecules. It has been a great challenge to observe and calculate real-time dynamics of such molecularized fermions. Here, we developed the non-empirical quantum molecular dynamics method that enables real-time molecular dynamics simulations of hydrogen molecules satisfying the nuclear spin statistics of the quantum rotor. While reproducing the species-dependent quantum rotational energy, population ratio, specific heat, and H-H bond length and frequency, we found that their translational, orientational and vibrational dynamics becomes accelerated with the higher rotational excitation, concluding that the nuclear quantum rotation stemmed from the nuclear spin statistics can induce various kinds of dynamics and reactions intrinsic to each hydrogen species.

Near-Unity Singlet Fission on a Quantum Dot Initiated by Resonant Energy Transfer.

The conversion of a high-energy photon into two excitons using singlet fission (SF) has stimulated a variety of studies in fields from fundamental physics to device applications. However, efficient SF has only been achieved in limited systems, such as solid crystals and covalent dimers. Here, we established a novel system by assembling 4-(6,13-bis(2-(triisopropylsilyl)ethynyl)pentacen-2-yl)benzoic acid (Pc) chromophores on nanosized CdTe quantum dots (QDs). A near-unity SF (198 ± 5.7%) initiated by interfacial resonant energy transfer from CdTe to surface Pc was obtained. The unique arrangement of Pc determined by the surface atomic configuration of QDs is the key factor realizing unity SF. The triplet-triplet annihilation was remarkably suppressed due to the rapid dissociation of triplet pairs, leading to long-lived free triplets. In addition, the low light-harvesting ability of Pc in the visible region was promoted by the efficient energy transfer (99 ± 5.8%) from the QDs to Pc. The synergistically enhanced light-harvesting ability, high triplet yield, and long-lived triplet lifetime of the SF system on nanointerfaces could pave the way for an unmatched advantage of SF.

Distinct molecular dynamics dividing liquid-like and gas-like supercritical hydrogens.

Understanding how a supercritical fluid is related to normal liquid and gas and separating it into liquid-like and gas-like regions are of fundamental and practical importance. Despite the usefulness of hydrogen storage, molecular dynamics images on supercritical hydrogens exhibiting strong nuclear quantum effects are scarce. Taking advantage of the non-empirical ab initio molecular dynamics method for hydrogen molecules, we found that, while radial distribution functions and diffusion show a monotonic change along the density, van Hove time correlation functions and intramolecular properties such as bond length and vibrational frequency exhibit the anomalous order crossing the Widom line. By demonstrating that the anomalous order stemmed from the largest deviations between liquid-like and gas-like solvations formed around the Widom line, we concluded that this supercritical fluid is a mixture of liquid and gas possessing heterogeneity. The obtained physical insights can be an index to monitor the supercriticality and to identify distinct liquid-like and gas-like supercritical fluids.

Fast T-Type Photochromism of Colloidal Cu-Doped ZnS Nanocrystals.

This paper reports on durable and nearly temperature-independent (at 298-328 K) T-type photochromism of colloidal Cu-doped ZnS nanocrystals (NCs). The color of Cu-doped ZnS NC powder changes from pale yellow to dark gray by UV light irradiation, and the color changes back to pale yellow on a time scale of several tens of seconds to minutes after stopping the light irradiation, while the decoloration reaction is accelerated to submillisecond in solutions. This decoloration reaction is much faster than those of conventional inorganic photochromic materials. The origin of the reversible photoinduced coloration is revealed to be a strong optical transition involving a delocalized surface hole which survives over a minute after escaping from intraparticle carrier recombination due to electron-hopping dissociation. ZnS NCs can be easily prepared in a water-mediated one-pot synthesis and are less toxic. Therefore, they are promising for large-scale photochromic applications such as windows and building materials in addition to conventional photochromic applications. Moreover, the present study demonstrates the importance of excited carrier dynamics and trap depths, resulting in coloration over minutes not only for photochromic nanomaterials but also for various advanced photofunctional materials, such as long persistent luminescent materials and photocatalytic nanomaterials.

Controlling the dimension of the quantum resonance in CdTe quantum dot superlattices fabricated via layer-by-layer assembly.

In quantum dot superlattices, wherein quantum dots are periodically arranged, electronic states between adjacent quantum dots are coupled by quantum resonance, which arises from the short-range electronic coupling of wave functions, and thus the formation of minibands is expected. Quantum dot superlattices have the potential to be key materials for new optoelectronic devices, such as highly efficient solar cells and photodetectors. Herein, we report the fabrication of CdTe quantum dot superlattices via the layer-by-layer assembly of positively charged polyelectrolytes and negatively charged CdTe quantum dots. We can thus control the dimension of the quantum resonance by independently changing the distances between quantum dots in the stacking (out-of-plane) and in-plane directions. Furthermore, we experimentally verify the miniband formation by measuring the excitation energy dependence of the photoluminescence spectra and detection energy dependence of the photoluminescence excitation spectra.

Decelerated Liquid Dynamics Induced by Component-Dependent Supercooling in Hydrogen and Deuterium Quantum Mixtures.

Isotopic mixtures of p-H2 and o-D2 molecules have been an attractive binary system because they include two kinds of purely isotopic molecules which possess the same electronic potential but the twice different mass inducing differently pronounced nuclear quantum effects (NQEs). Accessing details of structures and dynamics in such quantum mixtures combining complex molecular dynamics with NQEs of different strengths remains a challenging problem. Taking advantage of the nonempirical molecular dynamics method which describes p-H2 and o-D2 molecules, we found that the liquid dynamics slows down at a specific mixing ratio, which can be connected to the observed anomalous slowdown of crystallization in the quantum mixtures. We attributed the decelerated dynamics to the component-dependent supercooling of p-H2 taking place in the mixtures, demonstrating that there is an optimal mixing ratio to hinder crystallization. The obtained physical insights will help in experimentally controlling and achieving unknown quantum mixtures including superfluid.

Coupled electronic states in CdTe quantum dot assemblies fabricated by utilizing chemical bonding between ligands.

Semiconductor quantum dot superlattices (QDSLs) have attracted much attention as key materials for realizing new optoelectronic devices such as solar cells with high conversion efficiency and thermoelectric elements with high electrical conductivity. To improve the charge transport properties of QDSL-based optoelectronic devices, it is important that the QD structures form minibands, which are the coupled electronic states between QDs. A shorter inter-QD distance and a periodic arrangement of QDs are the essential conditions for the formation of minibands. In this study, we use CdTe QDs capped with short ligands of N-acetyl-l cysteine (NAC) to fabricate three-dimensional QD assemblies by utilizing chemical bonding between NACs. Absorption spectra clearly display the quantum resonance phenomenon originating from the coupling of the wave functions between the adjacent QDs in CdTe QD assemblies. Furthermore, we demonstrate the formation of minibands in CdTe QD assemblies by examining both, the excitation energy dependence of photoluminescence (PL) spectra and the detection energy dependence of PL excitation spectra. The fabrication method of QD assemblies utilizing chemical bonding between NACs can be applied to all QDs capped with NAC as a ligand.

Ultrafast Orbital Depolarization and Defect-Localized Phonon Dynamics Induced by Quantum Resonance between Multi-Nitrogen Vacancy Defects.

Proximate nitrogen-vacancy (NV) defects with interdefect interaction may establish a new kind of quantum qubit network to explore controlled multibody quantum dynamics. In particular, by introducing the critical distance and favorable orientation between a pair of NV defects, the quantum resonance (QR) can be induced. Here, we present the first real-time depolarization and phonon dynamics on the excited state at ambient temperature which are intrinsic to the proximate multi-NV defects. We computationally demonstrate that the QR can effectively change the major properties of the multi-NV defects, such as orbital degeneracy, orbital delocalization, local phonon modes, electron-phonon coupling, and orbital depolarization dynamics, elucidating the physical mechanisms and finding the key factors to control them. The physical insights provide a starting point for the positioning accuracy of NV defects and creation protocols with broad implications for magnetometry, quantum information, nanophotonics, sensing, and spectroscopy, allowing the QR to be a new means of physical manipulation.

Enhanced Breakthrough Efficiency by a Chemically Stable Porous Coordination Polymer with Optimized Nanochannel.

High separation efficiency is very important for process of pressure swing adsorption (PSA) in the industry. Herein, we propose a fine design of chemically stable porous coordination polymers (PCPs) with optimized nanochannel by strategy of inserting and shifting shortest alkyl group on T-shaped ligand. Remarkably, the synergistic effect of optimized nanochannel, unique crystal morphology and fitted channel enable sharply enhanced breakthrough efficiency of C2H6/4/CH4, 1.17 or 0.77 g of CH4 can be separated from corresponding dual mixtures (2/8, v/v) by 1 g of NTU-25 at 273 K, which was further validated and understood by controlled experiments and density functional theory (DFT) computations.

Isotopic Effects on Intermolecular and Intramolecular Structure and Dynamics in Hydrogen, Deuterium, and Tritium Liquids: Normal Liquid and Weakly and Strongly Cooled Liquids.

Differences in properties such as phase-transition temperature and transport coefficients among liquids of different isotopic compositions, hydrogen, deuterium, and tritium, should originate from their differently pronounced nuclear quantum effects (NQEs) rather than from any subtle difference in the electronic interaction potentials. Accurate and efficient determination of structural and dynamical isotopic effects in the quantum liquids still remains as one of the challenging problems in condensed-phase physics. With a recently developed nonempirical real-time molecular dynamics method which describes nonspherical molecules with the NQEs, we computationally realized and investigated dynamical and quantum isotopic effects of not only traditionally studied isotopes, hydrogen, and deuterium but also a lesser known radioisotope, tritium, in broad thermodynamic conditions from normal liquid to weakly and strongly cooled liquids, which have been hindered by rapid crystallization in spite of numerous experimental attempts at supercooling. Reproducing the previously reported experimental isotope dependence on the bond length and vibrational frequencies of hydrogen, deuterium, and tritium liquids, we further demonstrate that distinctive isotope effects appear in their intermolecular and intramolecular structure and dynamics not only at lower temperature but also at higher temperature, which none has so far been able to obtain quantitative results for realistic systems. Rationalization of their physical origins and the obtained physical insights will help future experimental searching and monitoring intermolecular and intramolecular dynamics and structures of these isotopes not only in normal liquid but also in supercooled liquid.

Control of Multiple Exciton Generation and Electron-Phonon Coupling by Interior Nanospace in Hyperstructured Quantum Dot Superlattice.

The possibility of precisely manipulating interior nanospace, which can be adjusted by ligand-attaching down to the subnanometer regime, in a hyperstructured quantum dot (QD) superlattice (QDSL) induces a new kind of collective resonant coupling among QDs and opens up new opportunities for developing advanced optoelectric and photovoltaic devices. Here, we report the first real-time dynamics simulations of the multiple exciton generation (MEG) in one-, two-, and three-dimensional (1D, 2D, and 3D) hyperstructured H-passivated Si QDSLs, accounting for thermally fluctuating band energies and phonon dynamics obtained by finite-temperature ab initio molecular dynamics simulations. We computationally demonstrated that the MEG was significantly accelerated, especially in the 3D QDSL compared to the 1D and 2D QDSLs. The MEG acceleration in the 3D QDSL was almost 1.9 times the isolated QD case. The dimension-dependent MEG acceleration was attributed not only to the static density of states but also to the dynamical electron-phonon couplings depending on the dimensionality of the hyperstructured QDSL, which is effectively controlled by the interior nanospace. Such dimension-dependent modifications originated from the short-range quantum resonance among component QDs and were intrinsic to the hyperstructured QDSL. We propose that photoexcited dynamics including the MEG process can be effectively controlled by only manipulating the interior nanospace of the hyperstructured QDSL without changing component QD size, shape, compositions, ligand, etc.

Dynamical Ordering of Hydrogen Molecules Induced by Heat Flux.

Achieving a direct nonequilibrium simulation for hydrogen systems has been quite challenging because nuclear quantum effects (NQEs) have to be taken into account. We directly simulated nonequilibrium hydrogen molecules under a temperature gradient with the recently developed nonempirical molecular dynamics method, which describes nonspherical hydrogen molecules with the NQEs. We found dynamical ordering purely induced by heat flux, which should be distinguished from static ordering like orientational alignment, as decelerated translational motions and enhanced intensity of H-H vibrational power spectra despite the little structural ordering. This dynamical ordering, which was enhanced with stronger heat flux while independent of system size, can be regarded as self-solidification of hydrogen molecules for their efficient heat conduction.

Density Gradation of Open Metal Sites in the Mesospace of Porous Coordination Polymers.

The prevalence of the condensed phase, interpenetration, and fragility of mesoporous coordination polymers (meso-PCPs) featuring dense open metal sites (OMSs) place strict limitations on their preparation, as revealed by experimental and theoretical reticular chemistry investigations. Herein, we propose a rational design of stabilized high-porosity meso-PCPs, employing a low-symmetry ligand in combination with the shortest linker, formic acid. The resulting dimeric clusters (PCP-31 and PCP-32) exhibit high surface areas, ultrahigh porosities, and high OMS densities (3.76 and 3.29 mmol g-1, respectively), enabling highly selective and effective separation of C2H2 from C2H2/CO2 mixtures at 298 K, as verified by binding energy (BE) and electrostatic potentials (ESP) calculations.

Jahn-Teller-induced femtosecond electronic depolarization dynamics of the nitrogen-vacancy defect in diamond.

Single-photon emission from the nitrogen-vacancy defect in diamond constitutes one of its many proposed applications. Owing to its doubly degenerate 3E electronic excited state, photons from this defect can be emitted by two optical transitions with perpendicular polarization. Previous measurements have indicated that orbital-selective photoexcitation does not, however, yield photoluminescence with well-defined polarizations, thus hinting at orbital-averaging dynamics even at cryogenic temperatures. Here we employ femtosecond polarization anisotropy spectroscopy to investigate the ultrafast electronic dynamics of the 3E state. We observe subpicosecond electronic dephasing dynamics even at cryogenic temperatures, up to five orders of magnitude faster than dephasing rates suggested by previous frequency- and time-domain measurements. Ab initio molecular dynamics simulations assign the ultrafast depolarization dynamics to nonadiabatic transitions and phonon-induced electronic dephasing between the two components of the 3E state. Our results provide an explanation for the ultrafast orbital averaging that exists even at cryogenic temperatures.