Doubly Spiro-Conjugated Chiral Carbocycles Exhibiting SOMO-HOMO Inversion in Persistent Radical Cations

Persistent chiral organic open-shell systems have captured growing interest due to their potential applications in organic spintronic and optoelectronic devices. Nevertheless, the integration of configurationally stable chirality into an organic open-shell system continues to pose challenges in molecular design. The π-extended skeleton incorporated in spiro-conjugated carbocycles can provide robust chiroptical properties and a significant stabilization of the excited and ionic radical states. However, this approach has been relatively less explored in the design of persistent organic open-shell systems. We report here the (S,S)-, (R,R)-, and meso-isomers of doubly spiro-conjugated carbocycles featuring flat and rigid carbon-bridged para-phenylenevinylene (CPV) of different conjugation lengths connected by two spiro-carbon centers, which we denote D-spiro-CPV for its quasi-dimeric structure. Our synthetic method based on a double lithiation cyclization approach enables facile production of D-spiro-CPV. D-spiro-CPVs exhibit circularly polarized luminescence (CPL) with high fluorescence quantum yields (ΦFL) resulting in a high CPL brightness of 21 M-1 cm-1 and also exhibit high thermal and photostability. The monoradical cation of D-spiro-CPV absorbing near-infrared light is notably persistent, exhibiting a half-life of 570 h under ambient conditions due to doubly spiro-conjugative stabilization. Theoretical and electrochemical studies indicate the radical cation of D-spiro-CPVs presents a non-Aufbau electron filling, exhibiting inversion of the energy level of the singly occupied molecular orbital (SOMO) and the highest (doubly) occupied molecular orbitals with the SOMO level even below the HOMO-1 level (double SHI effect). Our discoveries provide valuable insights into non-Aufbau molecules and the development of configurationally stable, optically active persistent radicals.

Cinematographic study of stochastic chemical events at atomic resolution

The advent of single-molecule atomic-resolution time-resolved electron microscopy (SMART-EM) has created a new field of 'cinematic chemistry,' allowing for the cinematographic recording of dynamic behaviors of organic and inorganic molecules and their assembly. However, the limited electron dose per frame of video images presents a major challenge in SMART-EM. Recent advances in direct electron counting cameras and techniques to enhance image quality through the implementation of a denoising algorithm have enabled the tracking of stochastic molecular motions and chemical reactions with sub-millisecond temporal resolution and sub-angstrom localization precision. This review showcases the development of dynamic molecular imaging using the SMART-EM technique, highlighting insights into nanomechanical behavior during molecular shuttle motion, pathways of multistep chemical reactions, and elucidation of crystallization processes at the atomic level.

Lateral Laxity in Flexion Influences Patient-Reported Outcome After Total Knee Arthroplasty

Introduction

Slight lateral laxity exists in normal knee especially in flexion. The lateral laxity in flexion has possibility to affect the outcome after total knee arthroplasty (TKA).

Purpose

The purpose of this study was to determine how intraoperative laxity in flexion affects patient-reported outcome after total knee arthroplasty.

Methods

We retrospectively analysed 98 knees with osteoarthritis that underwent total knee arthroplasty. After bone resection, ligament imbalance and joint component gaps were measured using an offset-type tensor while applying a 40-lb joint distraction force at 0° and 90° of knee flexion. The lateral laxity in flexion was determined by subtracting polyethylene insert thickness from the lateral gap at 90°. All patients were divided into three groups: ≤ 2 mm (A), 2-5 mm (B), and > 5 mm (C). One year after surgery, patients were asked to fill out questionnaires using the new Knee Society Score after examination outside the consultation room.

Results

The mean intraoperative lateral laxities at 90° were - 0.2 ± 2.1 mm, 3.5 ± 0.7 mm, and 6.7 ± 1.9 mm in groups A, B, and C, respectively. The symptom score of group C was significantly lower than those of groups A or B. There were no significant differences in terms of satisfaction or the expectation and activity scores among all groups. There were no significant differences in terms of alignment after total knee arthroplasty among all groups.

Conclusions

Excessive lateral laxity possibly resulted in worse patient-reported outcomes. However, slight lateral laxity of 2-5 mm might have no effect on patient-reported outcome and this slight varus imbalance could be acceptable. Altogether, our findings would lead to avoidance of excessive medial release in soft tissue balancing.

Time-resolved imaging and analysis of the electron beam-induced formation of an open-cage metallo-azafullerene

The visualization of single-molecule reactions provides crucial insights into chemical processes, and the ability to do so has grown with the advances in high-resolution transmission electron microscopy. There is currently a limited mechanistic understanding of chemical reactions under the electron beam. However, such reactions may enable synthetic methodologies that cannot be accessed by traditional organic chemistry methods. Here we demonstrate the synthetic use of the electron beam, by in-depth single-molecule, atomic-resolution, time-resolved transmission electron microscopy studies, in inducing the formation of a doubly holed fullerene-porphyrin cage structure from a well-defined benzoporphyrin precursor deposited on graphene. Through real-time imaging, we analyse the hybrid's ability to host up to two Pb atoms, and subsequently probe the dynamics of the Pb-Pb binding motif in this exotic metallo-organic cage structure. Through simulation, we conclude that the secondary electrons, which accumulate in the periphery of the irradiated area, can also initiate chemical reactions. Consequently, designing advanced carbon nanostructures by electron-beam lithography will depend on the understanding and limitations of molecular radiation chemistry.

Frequency-domain interferometry for the determination of time delay between two extreme-ultraviolet wave packets generated by a tandem undulator

Synchrotron radiation, emitted by relativistic electrons traveling in a magnetic field, has poor temporal coherence. However, recent research has proved that time-domain interferometry experiments, which were thought to be enabled by only lasers of excellent temporal coherence, can be implemented with synchrotron radiation using a tandem undulator. The radiation generated by the tandem undulator comprises pairs of light wave packets, and the longitudinal coherence within a light wave packet pair is used to achieve time-domain interferometry. The time delay between two light wave packets, formed by a chicane for the electron trajectory, can be adjusted in the femtosecond range by a standard synchrotron technology. In this study, we show that frequency-domain spectra of the tandem undulator radiation exhibit fringe structures from which the time delay between a light wave packet pair can be determined with accuracy on the order of attoseconds. The feasibility and limitations of the frequency-domain interferometric determination of the time delay are examined.

Wavy Graphene-Like Network Forming during Pyrolysis of Polyacrylonitrile into Carbon Fiber

Carbon fiber (CF) obtained by pyrolysis of polyacrylonitrile (PAN-CF) surpasses metals in properties suitable for diverse applications such as aircraft manufacture and power turbine blades. PAN-CF obtained by pyrolysis at 1200-1400 °C shows a remarkably high tensile strength of 7 GPa, much higher than pitch-based CF (pb-CF) consisting of piles of pure graphene networks. However, little information has been available on the atomistic structure of PAN-CF and on how it forms during pyrolysis. We pyrolyzed an acrylonitrile 9-mer in a carbon nanotube, monitored the course of the reaction using atomic-resolution electron microscopy and Raman spectroscopy, and found that this oligomer forms a thermally reactive wavy graphene-like network (WGN) at 1200-1400 °C during slow graphitization taking place between 900 and 1800 °C. Ptychographic microscopic analysis indicated that such material consists of 5-, 6-, and larger-membered rings; hence, it is not flat but wavy. The experimental data suggest that, during PAN-CF manufacturing, many layers of WGN hierarchically pile up to form a chemically and physically interdigitated noncrystalline phase that resists fracture and increases the tensile strength─the properties expected for high-entropy materials. pb-CF using nearly pure carbon starting material, on the other hand, forms a crystalline graphene network and is brittle.

Cinematographic Recording of a Metastable Floating Island in Two- and Three-Dimensional Crystal Growth

Many chemical reactions go through a cascade of events in which a series of metastable intermediates appear, and crystal nucleation is no exception. Although the consensus on the energetics of nucleation suggests the formation of metastable states preceding the crystal growth, little experimental evidence has been reported for their dynamics at an atomistic level. Operando imaging of two-dimensional nucleation on a defect-free NaCl nanocrystal in carbon nanotubes using a millisecond angstrom-resolution transmission electron microscope revealed the formation of a metastable "floating island" (FI) that migrates thermally on the (100) facet of NaCl as the first intermediate of epitaxy. The speed of the migration at 298 K is estimated to be larger than 0.3 nm ms^-1. When a crystal tumbles in a container, a space repeatedly forms between the crystal and the container wall that hosts the FI. Tumbling changes the surface energy repeatedly and promotes the conversion of the FI into a new epitaxial layer. We anticipate that this surface catalysis mechanism found on the nanoscale also operates in bulk heterogeneous nucleation where agitation and attrition accelerate crystallization.

Atomically Precise Incorporation of BN-Doped Rubicene into Graphene Nanoribbons

Substituting heteroatoms and non-benzenoid carbons into nanographene structure offers a unique opportunity for atomic engineering of electronic properties. Here we show the bottom-up synthesis of graphene nanoribbons (GNRs) with embedded fused BN-doped rubicene components on a Au(111) surface using on-surface chemistry. Structural and electronic properties of the BN-GNRs are characterized by scanning tunneling microscopy (STM) and atomic force microscopy (AFM) with CO-terminated tips supported by numerical calculations. The periodic incorporation of BN heteroatoms in the GNR leads to an increase of the electronic band gap as compared to its undoped counterpart. This opens avenues for the rational design of semiconducting GNRs with optoelectronic properties.

Versatile Synthesis of Trisphosphines Bearing Phenylene and Vinylene Backbones Useful for Metal Catalysis and Materials Applications

Trisphosphines, in which two phenylene or vinylene backbones connect three phosphine atoms, belong to an emerging class of ligands in metal-catalyzed organic synthesis and materials applications. However, these ligands were previously known only in a small variety because of the synthetic limitations. We report herein two versatile synthetic routes to a hitherto unavailable variety of trisphosphines. The compounds bearing phenylene backbones were synthesized by sequential addition of two different organolithium reagents to triphenyl phosphite and that with vinylene backbones by stereoretentive addition of lithium diarylphosphide to a cis-bromoalkene. The new trisphosphine compounds will serve as valuable tools for the development of transition-metal-catalyzed reactions and functional materials.

Time-Resolved Atomistic Imaging and Statistical Analysis of Daptomycin Oligomers with and without Calcium Ions

Daptomycin (DP) is effective against multiple drug-resistant Gram-positive pathogens because of its distinct mechanism of action. An accepted mechanism includes Ca²⁺-triggered aggregation of the DP molecule to form oligomers. DP and its oligomers have so far defied structural analysis at a molecular level. We studied the ability of DP molecule to aggregate by itself in water, the effects of Ca²⁺ ions to promote the aggregation, and the connectivity of the DP molecules in the oligomers by the combined use of dynamic light scattering in water and atomic-resolution cinematographic imaging of DP molecules captured on a carbon nanotube on which the DP molecule is installed as a fishhook. We found that the DP molecule aggregates weakly into dimers, trimers, and tetramers in water, and strongly in the presence of calcium ions, and that the tetramer is the largest oligomer in homogeneous aqueous solution. The dimer remains as the major species, and we propose a face-to-face stacked structure based on dynamic imaging using millisecond and angstrom resolution transmission electron microscopy. The tetramer in its cyclic form is the largest oligomer observed, while the trimer forms in its linear form. The study has shown that the DP molecule has an intrinsic property of forming tetramers in water, which is enhanced by the presence of calcium ions. Such experimental structural information will serve as a platform for future drug design. The data also illustrate the utility of cinematographic recording for the study of self-organization processes.

Triarylamine/Bithiophene Copolymer with Enhanced Quinoidal Character as Hole-Transporting Material for Perovskite Solar Cells

Polytriarylamine is a popular hole-transporting materials (HTMs) despite its suboptimal conductivity and significant recombination at the interface in a solar cell setup. Having noted insufficient conjugation among the triarylamine units along the polymer backbone, we inserted a bithiophene unit between two triarylamine units through iron-catalyzed C-H/C-H coupling of a triarylamine/thiophene monomer so that two units conjugate effectively via four quinoidal rings when the molecule functions as HTM. The obtained triarylamine/bithiophene copolymer (TABT) used as HTM showed a high-performance in methylammonium lead iodide perovskite (MAPbI₃ ) solar cells. Mesityl substituted TABT forms a uniform film, shows high hole-carrier mobility, and has an ionization potential (IP=5.40 eV) matching that of MAPbI₃ . We fabricated a solar cell device with a power conversion efficiency of 21.3 % and an open-circuit voltage of 1.15 V, which exceeds the performance of devices using reference standard such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) and Spiro-OMeTAD.

Time-Resolved Imaging of Stochastic Cascade Reactions over a Submillisecond to Second Time Range at the Angstrom Level

Many chemical reactions, such as multistep catalytic cycles, are cascade reactions in which a series of transient intermediates appear and disappear stochastically over an extended period. The mechanisms of such reactions are challenging to study, even in ultrafast pump-probe experiments. The dimerization of a van der Waals dimer of [60]fullerene producing a short carbon nanotube is a typical cascade reaction and is probably the most frequently studied in carbon materials chemistry. As many as 23 intermediates were predicted by theory, but only the first stable one has been verified experimentally. With the aid of fast electron microscopy, we obtained cinematographic recordings of individual molecules at a maximum frame rate of 1600 frames per second. Using Chambolle total variation algorithm processing and automated cross-correlation image matching analysis, we report on the identification of several metastable intermediates by their shape and size. Although the reaction events occurred stochastically, varying the lifetime of each intermediate accordingly, the average lifetime for each intermediate structure could be obtained from statistical analysis of many cinematographic images for the cascade reaction. Among the shortest-living intermediates, we detected one that lasted less than 3 ms in three independent cascade reactions. We anticipate that the rapid technological development of microscopy and image processing will soon initiate an era of cinematographic studies of chemical reactions and cinematic chemistry.

De Novo Synthesis of Free-Standing Flexible 2D Intercalated Nanofilm Uniform over Tens of cm2

Of a variety of intercalated materials, 2D intercalated systems have attracted much attention both as materials per se, and as a platform to study atoms and molecules confined among nanometric layers. High-precision fabrication of such structures has, however, been a difficult task using the conventional top-down and bottom-up approaches. The de novo synthesis of a 3-nm-thick nanofilm intercalating a hydrogen-bonded network between two layers of fullerene molecules is reported here. The two-layered film can be further laminated into a multiply film either in situ or by sequential lamination. The 3 nm film forms uniformly over an area of several tens of cm² at an air/water interface and can be transferred to either flat or perforated substrates. A free-standing film in air prepared by transfer to a gold comb electrode shows proton conductivity up to 1.4 × 10^-4 S cm^-1 . Electron-dose-dependent reversible bending of a free-standing 6-nm-thick nanofilm hung in a vacuum is observed under electron beam irradiation.

A Singular Molecule-to-Molecule Transformation on Video: The Bottom-Up Synthesis of Fullerene C60 from Truxene Derivative C60H30

Singular reaction events of small molecules and their dynamics remain a hardly understood territory in chemical sciences since spectroscopy relies on ensemble-averaged data, and microscopic scanning probe techniques show snapshots of frozen scenes. Herein, we report on continuous high-resolution transmission electron microscopic video imaging of the electron-beam-induced bottom-up synthesis of fullerene C₆₀ through cyclodehydrogenation of tailor-made truxene derivative 1 (C₆₀H₃₀), which was deposited on graphene as substrate. During the reaction, C₆₀H₃₀ transformed in a multistep process to fullerene C₆₀. Hereby, the precursor, metastable intermediates, and the product were identified by correlations with electron dose-corrected molecular simulations and single-molecule statistical analysis, which were substantiated with extensive density functional theory calculations. Our observations revealed that the initial cyclodehydrogenation pathway leads to thermodynamically favored intermediates through seemingly classical organic reaction mechanisms. However, dynamic interactions of the intermediates with the substrate render graphene as a non-innocent participant in the dehydrogenation process, which leads to a deviation from the classical reaction pathway. Our precise visual comprehension of the dynamic transformation implies that the outcome of electron-beam-initiated reactions can be controlled with careful molecular precursor design, which is important for the development and design of materials by electron beam lithography.

Iron-Catalyzed Tandem Cyclization of Diarylacetylene to a Strained 1,4-Dihydropentalene Framework for Narrow-Band-Gap Materials

Carbon bridging in a form of a strained 1,4-dihydropentalene framework is an effective strategy for flattening and stabilizing oligophenylenevinylene systems for the development of optoelectronic materials. However, efficient and flexible methods for making such a strained ring system are lacking. We report herein a mild and versatile synthetic access to the 1,4-dihydropentalene framework enabled by iron-catalyzed single-pot tandem cyclization of a diarylacetylene using FeCl₂ and PPh₃ as catalyst, magnesium/LiCl as a reductant, and 1,2-dichloropropane as a mild oxidant. The new annulation method features two iron-catalyzed transformations used in tandem, a reductive acetylenic carboferration and an oxidation-induced ring contraction of a ferracycle under mild oxidative conditions. The new method provides access not only to a variety of substituted indeno[2,1-a]indenes but also to their thiophene congeners, 4,9-dihydrobenzo[4,5]pentaleno[1,2-b]thiophene (CPTV) and 4,8-dihydropentaleno[1,2-b:4,5-b']dithiophenes (CTV). With its high highest occupied molecular orbital level and narrow optical gap, CTV serves as a donor unit in a narrow-band-gap non-fullerene acceptor, which shows absorption extending over 1000 nm in the film state, and has found use in a near-infrared photodetector device that exhibited an external quantum efficiency of 72.4% at 940 nm.

Rim Binding of Cyclodextrins in Size-Sensitive Guest Recognition

Cyclodextrins (CDs) are doughnut-shaped cyclic oligosaccharides having a cavity and two rims. Inclusion binding in the cavity has long served as a classic model of molecular recognition, and rim binding has been neglected. We found that CDs recognize guests by size-sensitive binding using the two rims in addition to the cavity, using single-molecule electron microscopy and a library of graphitic cones as a solid-state substrate for complexation. For example, with its cavity and rim binding ability combined, γ-CD can recognize a guest of radius between 4 and 9 Å with a size-recognition precision of better than 1 Å, as shown by structural analysis of thousands of individual specimens and statistical analysis of the data thereof. A 2.5 ms resolution electron microscopic video provided direct evidence of the process of size recognition. The data suggest the occurrence of the rim binding mode for guests larger than the size of the CD cavity and illustrate a unique application of dynamic molecular electron microscopy for deciphering the spatiotemporal details of supramolecular events.

Nano- and Microspheres Containing Inorganic and Biological Nanoparticles: Self-Assembly and Electron Tomographic Analysis

Organofullerene amphiphiles show diverse behaviors in water, forming vesicles, micelles, Langmuir-Blodgett films, and anisotropic nanostructures. We found that gradual in situ protonation of an organic solution of (4-heptylphenyl)₅C₆₀^-K⁺ by water or buffer generates the corresponding protonated molecule, (4-heptylphenyl)₅C₆₀H, which self-assembles to form nano- and microspheres of organofullerene (fullerspheres) with uniform diameters ranging from 30 nm to 2.5 μm that are controlled by the preparation or pH of the buffer. By using an aqueous solution of an organic dye, inorganic nanoparticle, protein, and virus, we encapsulated these entities in the fullersphere. This approach via self-assembly is distinct from other preparations of organic core-shell particles that generally require polymerization for the construction of a robust shell. The sphere is entirely amorphous, thermally stable up to 300 °C under vacuum, and resistant to electron irradiation, and we found the unconventional utility of the sphere for electron tomographic imaging of nanoparticles and biomaterials.

Capturing the Moment of Emergence of Crystal Nucleus from Disorder

Crystallization is the process of atoms or molecules forming an organized solid via nucleation and growth. Being intrinsically stochastic, the research at an atomistic level has been a huge experimental challenge. We report herein in situ detection of a crystal nucleus forming during nucleation/growth of a NaCl nanocrystal, as video recorded in the interior of a vibrating conical carbon nanotube at 20-40 ms frame^-1 with localization precision of <0.1 nm. We saw NaCl units assembled to form a cluster fluctuating between featureless and semiordered states, which suddenly formed a crystal. Subsequent crystal growth at 298 K and shrinkage at 473 K took place also in a stochastic manner. Productive contributions of the graphitic surface and its mechanical vibration have been experimentally indicated.

SHROOM3, the gene associated with chronic kidney disease, affects the podocyte structure

Chronic kidney disease is a public health burden and it remains unknown which genetic loci are associated with kidney function in the Japanese population, our genome-wide association study using the Biobank Japan dataset (excluding secondary kidney diseases, such as diabetes mellitus) clearly revealed that almost half of the top 50 single nucleotide polymorphisms associated with estimated glomerular filtration rate are located in the SHROOM3 gene, suggesting that SHROOM3 will be responsible for kidney function. Thus, to confirm this finding, supportive functional analyses were performed on Shroom3 in mice using fullerene-based siRNA delivery, which demonstrated that Shroom3 knockdown led to albuminuria and podocyte foot process effacement. The in vitro experiment shows that knockdown of Shroom3 caused defective formation of lamellipodia in podocyte, which would lead to the disruption of slit diaphragm. These results from the GWAS, in vivo and in vitro experiment were consistent with recent studies reporting that albuminuria leads to impairment of kidney function.

Ultra-Fast Electron Microscopic Imaging of Single Molecules With a Direct Electron Detection Camera and Noise Reduction

Time-resolved imaging of molecules and materials made of light elements is an emerging field of transmission electron microscopy (TEM), and the recent development of direct electron detection cameras, capable of taking as many as 1,600 fps, has potentially broadened the scope of the time-resolved TEM imaging in chemistry and nanotechnology. However, such a high frame rate reduces electron dose per frame, lowers the signal-to-noise ratio (SNR), and renders the molecular images practically invisible. Here, we examined image noise reduction to take the best advantage of fast cameras and concluded that the Chambolle total variation denoising algorithm is the method of choice, as illustrated for imaging of a molecule in the 1D hollow space of a carbon nanotube with ~1 ms time resolution. Through the systematic comparison of the performance of multiple denoising algorithms, we found that the Chambolle algorithm improves the SNR by more than an order of magnitude when applied to TEM images taken at a low electron dose as required for imaging at around 1,000 fps. Open-source code and a standalone application to apply Chambolle denoising to TEM images and video frames are available for download.

Chromium(III)-Catalyzed C(sp2)-H Alkynylation, Allylation, and Naphthalenation of Secondary Amides with Trimethylaluminum as Base

Among base metals used for C-H activation reactions, chromium(III) is rather unexplored despite its natural abundance and low toxicity. We report herein chromium(III)-catalyzed C(sp²)-H functionalization of an ortho-position of aromatic and α,β-unsaturated secondary amides using readily available AlMe₃ as a base and using bromoalkynes, allyl bromide, and 1,4-dihydro-1,4-epoxynaphthalene as electrophiles. This redox-neutral reaction taking place at 70-90 °C, requires as low as 1-2 mol % of CrCl₃ or Cr(acac)₃ as a catalyst without any added ligand, and tolerates functional groups such as aryl iodide, boronate, and thiophene groups. Stoichiometric and kinetics studies as well as kinetic isotope effects suggest that the catalytic cycle consists of a series of thermally stable but reactive intermediates bearing two molecules of the amide substrate on one chromium atom and also that one of these chromate(III) complexes takes part in the alkynylation, allylation, and naphthalenation reactions. The proposed mechanism accounts for the effective suppression of methyl group delivery from AlMe₃ for ortho-C-H methylation.

Preparation of Hierarchically Assembled Silver Nanostructures based on the Morphologies of Crystalline Peptide-Silver(I) Complexes

The preparation of a hierarchically assembled Ag nanostructures based on a nanocrystalline assembly was demonstrated using an Ag(I) complex of a dipeptide (AspDap). By heating under N₂ gas, a spherical assembly of a nanocrystalline dipeptide-Ag(I) complex (diameter 4-5 μm), which has a morphology similar to the assembled structure of the dipeptide, was transformed to an assembly of Ag nanostructures, where the micrometre-order crystalline morphology was maintained. In addition, detailed scanning electron microscopy studies revealed that Ag nanoparticles (diameter ca. 10 nm) were formed on the surface of the Ag nanostructure. When the Ag(I) ions were reduced to Ag(0), this phenomenon exhibited surface dependence due to the anisotropic two-dimensional Ag(I) arrangement in the crystals. Thermogravimetric measurements and X-ray photoelectron spectroscopy revealed that the reduction proceeds in a stepwise manner around 200-250 °C, together with the removal of primary and secondary carboxylic groups in the dipeptide. Comparison with the heating process of the crystalline Ag(I) complex of β-alanine indicated that stepwise reduction is key for maintaining the original micrometre-order morphology.

Bifurcation of self-assembly pathways to sheet or cage controlled by kinetic template effect

The template effect is a key feature to control the arrangement of building blocks in assemblies, but its kinetic nature remains elusive compared to the thermodynamic aspects, with the exception of very simple reactions. Here we report a kinetic template effect in a self-assembled cage composed of flexible ditopic ligands and Pd(II) ions. Without template anion, a micrometer-sized sheet is kinetically trapped (off-pathway), which is converted into the thermodynamically most stable cage by the template anion. When the template anion is present from the start, the cage is selectively produced by the preferential cyclization of a dinuclear intermediate (on-pathway). Quantitative and numerical analyses of the self-assembly of the cage on the on-pathway revealed that the accelerating effect of the template is stronger for the early stage reactions of the self-assembly than for the final cage formation step itself, indicating the kinetic template effect.

Carbon-Bridged Oligo(phenylene vinylene)s: A de Novo Designed, Flat, Rigid, and Stable π-Conjugated System

The modern history of conducting organic systems started with a fortuitous error in 1967 on acetylene polymerization, followed by a rational discovery in 1976 on the effects of doping that generates a polaron and, hence, dramatically increases conductivity. Not unexpectedly, however, the prototypical polyacetylene suffers many problems, including C-C single bond rotation, short effective conjugation length, radiationless deactivation, and instability of the polarons. Several strategies have been put in place to solve these problems. An early approach relied on partial rigidification of the polyene structure by conversion into polymers with thiophene, pyrrole, and benzene linkages. An oligo(phenylene vinylene) (OPV) is an all-carbon analogue of polyacetylene, where every other diene unit in the polyene chain is converted to a benzene unit, still leaving many C-C single bonds freely rotating in the molecule. We considered adding additional carbon bridges to rigidify the OPV skeleton entirely to create a carbon-bridged OPV (COPV). Making such a compound was an obvious challenge. This Account describes the authors' efforts to design and synthesize a series of COPV molecules, where the benzene rings in OPV are bridged by sp³ carbon atoms to form a bicyclo[3.3.0]octatriene framework bearing a tetrasubstituted olefin at the ring fusion. This olefinic bond is so strained that it resists further deformation or conversion to sp³ centers, and hence, it is chemically stable despite the strain. The sp³ carbon bridges can bear organic side chains that hinder intermolecular interactions, rendering the excited states stable and long-lived even in the solid state. They also increase solubility, a common problem among rigid molecular systems. With these structural features, the COPV molecules were found to be well behaved both at a single-molecule level and as a bulk material. We reported in 2009 a method for the synthesis of COPVs and have, since then, reported their structures and physicochemical properties, including basic photophysical properties of neutral and charged derivatives, thermal and photostability, and fast electron transfer. These properties have rendered the COPV molecules useful for electronic and photonic research, for example, lasers, solar cells, and molecular wire applications. Noteworthy discoveries in the area connecting chemistry and physics include inelastic tunneling and long-range resonance tunneling at ambient temperature, which were previously observed only for organic molecular wires placed under cryogenic conditions. Given the ready availability of the COPV skeleton bearing a wide variety of substituents, this class of molecules will serve as versatile building blocks for fundamental and applied research on physicochemical and materials chemistry.

P767Survey of palliative sedation at the end-of-life in terminally ill heart failure patients - a five year experience in national cardiovascular center

Background

Palliative sedation is a therapeutic option when symptom relief is difficult to achieve at the end-of-life. However, little is known regarding palliative sedation in terminally ill heart failure (HF) patients.

Purpose

To survey the practice of palliative sedation in terminally ill HF patients at a tertiary referral cardiovascular center, and to investigate the efficacy and safety of sedative agents in HF patients.

Methods

We retrospectively reviewed consecutive patients who were referred to palliative care team at our institution between September 2013 and August 2018. Patients who were hospitalized for HF and died during hospitalization despite optimal medical therapy were selected and defined as terminally ill HF. We investigated the practice of palliative sedation in terminally ill HF patients and analysed the vital signs and sedation scale before starting sedative agents and about 1 hour afterward.

Results

Among 95 terminally ill HF patients, 37 were prescribed palliative sedation at the end-of-life (Picture). Of 37 patients (mean age: 70 years, median B-type natriuretic peptide: 1018 pg/ml, median creatinine: 3.0 mg/dl, intravenous inotrope: 81%), 25 were prescribed dexmedetomidine, and 12 were prescribed midazolam as first agent for sedation. Patient's backgrounds were comparable between the two groups. Richmond Agitation-Sedation Scale was significantly reduced (P<0.01), whereas blood pressure and heart rate were not altered after treatments in both groups. In midazolam group, significant decreases were noted regarding respiratory rate (P=0.01) and oxygen saturation (P=0.02); however, these parameters were not changed in dexmedetomidine group (Table).

Table 1. Vital signs and sedation scale Dexmedetomidine group (n=25) Midazolam group (n=12) Baseline After P value Baseline After P value Richmond Agitation-Sedation Scale 1 (0, 1) −1 (−2, 0) <0.01 1 (0, 1) −2 (−3, −1) <0.01 Vital signs   Systolic blood pressure (mmHg) 90±15 89±16 0.51 89±21 84±23 0.33   Diastolic blood pressure (mmHg) 52±13 54±11 0.34 60±14 56±23 0.48   Heart rate (beats per minute) 95±20 91±22 0.17 90±21 90±19 0.70   Respiratory rate (breaths per minute) 22±5 20±5 0.24 21±5 17±2 0.01   Oxygen saturation (%) 97±3 96±6 0.59 96±5 94±5 0.02

Picture. Study flowchart

Conclusions

Dexmedetomidine and midazolam were commonly used in real-word practice for HF patients at the end-of-life. Although impact on respiratory system differed by treatments, both agents could be prescribed effectively and safely in terminally ill HF patients.

Interfacial Chemistry of Conical Fullerene Amphiphiles in Water

Amphiphiles are used for a variety of applications in our daily life and in industrial processes. They typically possess hydrophobic and hydrophilic moieties within the molecule, thereby performing a myriad of functions through the formation of two- and three-dimensional assemblies in water, such as Gibbs monolayers and micelles. However, these functions are often inseparable because they emerge from the same structural feature of the molecule, and are difficult to control because the structural diversity is limited to either long-chain hydrocarbons bearing a polar end group(s) or polymers bearing polar groups exposed to the exterior surface. In this Account, we describe the chemistry of a new class of amphiphiles, conical fullerene amphiphiles (CFAs), utilizing a superhydrophobic [60]fullerene group as a nonpolar apex with added structural features to make it soluble in water. By selective functionalization of only one side of the fullerene molecule, the CFA molecules spontaneously assemble in water through strong hydrophobic interactions among the fullerene apexes and exhibit unusual supramolecular and interfacial behavior. They form unilamellar micelles and vesicles at a critical aggregation concentration as low as micromolar, not showing any air-water and oil-water interfacial activity. The strong preference for self-assembly in water over monolayer formation at an air-water interface makes CFAs unique among conventional nonpolymeric surfactants. The CFA assemblies are often so mechanically robust that they can be transferred to the surface of a solid substrate and analyzed by high-resolution microscopy. Because of this rigid conical structure of a few nanometers in size, CFA molecules aggregate readily in water to form a hierarchical assembly with biomolecules and nanomaterials while maintaining the structural integrity of the CFA aggregate to form multicomponent agglomerates of controllable structural features. For instance, tissue-selective in vivo transport of DNA and siRNA has been achieved. Hybridization of a CFA vesicle with a transition metal catalyst enables the construction of a structurally defined nanospace and an interface for precise control of the nanoscale morphology of polymers. Solubilization of hydrophobic nanocarbons and nanoparticles is also achieved through hemimicelle formation on solid surfaces. The examples reported here illustrate the potential of the conical fullerene motif for the design of amphiphiles as well as supramolecular structures at molecular and tens of nanometers scale.

Organic/Inorganic Hybrid p-Type Semiconductor Doping Affords Hole Transporting Layer Free Thin-Film Perovskite Solar Cells with High Stability

A feature of perovskite devices is their suitability in the fabrication of semitransparent solar cells (ST-SCs). Methylammonium lead iodide based perovskite material (MAPbI₃ or PV) is a possible material of choice because of its semitransparent nature in thin film form and after considering a balance among average visible light transmittance (AVT), power conversion efficiency (PCE), and device stability. However, there are issues to be addressed in the design of PV ST-SCs, such as the stability of small grain crystals forming in thin films and reducing the number of layers in the device to increase AVT. We report herein that doping PV with a 0.03 wt % hybrid organic p-type semiconductor, fluorinated tetraarylbenzo [1,2- b:4,5- b']dipyrrol-1,5-yl alkanediylsulfonate salt (BDPSO), affords a device with a 280 nm active layer directly fabricated on an indium tin oxide/glass substrate, without fabricating a hole transporting layer. Such a device exhibited a 30% higher PCE of 16.9% than the device made without doping. This device exhibited a stable photocurrent output at the maximum power point (MPP) for >1000 s under air and an operational stability of retaining 93% of the initial PCE after 1000 h continuous light soaking at the MPP. The ST-SC devices made of BDPSO-doped 140 nm and 90 nm thick PV films and a 6 nm thick Au electrode achieved PCEs of 10.3 and 8.0% and whole device semitransparency values of 22 and 30% AVT, respectively. The origins of the observed doping effect of BDPSO are ascribed to the bissulfonate structure that can effectively passivate defects at the interface and grain boundaries and to the HOMO level matching with PV to facilitate charge transfer.

Fibroblast Growth Factor 2 Enhances Tendon-to-Bone Healing in a Rat Rotator Cuff Repair of Chronic Tears

BACKGROUND

The effects of fibroblast growth factor 2 (FGF-2) on healing after surgical repair of chronic rotator cuff (RC) tears remain unclear.

HYPOTHESIS

FGF-2 enhances tenogenic healing response, leading to biomechanical and histological improvement of repaired chronic RC tears in rats.

STUDY DESIGN

Controlled laboratory study.

METHODS

Adult male Sprague-Dawley rats (n = 117) underwent unilateral surgery to refix the supraspinatus tendon to its insertion site 3 weeks after detachment. Animals were assigned to either the FGF-2 group or a control group. The effects of FGF-2 were assessed via biomechanical tests at 3 weeks after detachment and at 6 and 12 weeks postoperatively and were assessed histologically and immunohistochemically for proliferating cell nuclear antigen and mesenchymal stem cell (MSC)-related markers at 2, 6, and 12 weeks postoperatively. The expression of tendon/enthesis-related markers, including SRY-box 9 (Sox9), scleraxis (Scx), and tenomodulin (Tnmd), were assessed by real-time reverse transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry. The effect of FGF-2 on comprehensive gene expressions at the healing site was evaluated by microarray analysis.

RESULTS

The FGF-2 group showed a significant increase in mechanical strength at 6 and 12 weeks compared with control; the FGF-2 group also showed significantly higher histological scores at 12 weeks than control, indicating the presence of more mature tendon-like tissue. At 12 weeks, Scx and Tnmd expression increased significantly in the FGF-2 group, whereas no significant differences in Sox9 were found between groups over time. At 2 weeks, the percentage of positive cells expressing MSC-related markers increased in the FGF-2 group. Microarray analysis at 2 weeks after surgery showed that the expression of several growth factor genes and extracellular matrix-related genes was influenced by FGF-2 treatment.

CONCLUSION

FGF-2 enhanced the formation of tough tendon-like tissues including an increase in Scx- or Tnmd-expressing cells at 12 weeks after surgical repair of chronic RC tears. The increase in mesenchymal progenitors and the changes in gene expression upon FGF-2 treatment in the early phase of healing appear to be related to a certain favorable microenvironment for tenogenic healing response of chronic RC tears.

CLINICAL RELEVANCE

These findings may provide advantages in therapeutic strategies for patients with RC tears.

Carbon-bridged Oligo(phenylenevinylene)s as Light-harvesting Antenna for Porphyrins

The efficacy of carbon-bridged oligo(phenylenevinylenes)s (COPVs) as light-harvesting antenna for porphyrins is demonstrated using a series of 5,15-di-COPVn-substituted free-base and zinc porphyrins, COPVn-MP-COPVn (n=1-3, M=H₂ , Zn). These molecules were synthesized by Suzuki-Miyaura cross-coupling reactions of COPVn-Bpin and Br-H₂ P-Br. The absorption spectra of these compounds in solution show a significant expansion of the Soret band region together with a bathochromic shift of the Q band, suggesting a significant interaction between these chromophores in the ground state. The photoluminescence quantum yield of the porphyrin-COPV conjugates is enhanced up to four times relative to the parent porphyrins. Theoretical calculations also indicated interactions between these chromophores in the HOMO, which suggests that the light-harvesting ability stems from the expansion of the π-electron-conjugation system.

Angiopoietin-Like Protein 2 Induces Synovial Inflammation in the Facet Joint Leading to Degenerative Changes via Interleukin-6 Secretion

Study Design

Experimental human study.

Purpose

To determine whether angiopoietin-like protein 2 (ANGPTL2) is highly expressed in the hyperplastic facet joint (FJ) synovium and whether it activates interleukin-6 (IL-6) secretion in FJ synoviocytes.

Overview of Literature

Mechanical stress-induced synovitis is partially, but significantly, responsible for degenerative and subsequently osteoarthritic changes in the FJ tissues in patients with lumbar spinal stenosis (LSS). However, the underlying molecular mechanism remains unclear. IL-6 is highly expressed in degenerative FJ synovial tissue and is responsible for local chronic inflammation. ANGPTL2, an inflammatory and mechanically induced mediator, promotes the expression of IL-6 in many cells.

Methods

FJ tissues were harvested from five patients who had undergone lumbar surgery. Immunohistochemistry for ANGPTL2, IL-6, and cell markers was performed in the FJ tissue samples. After cultured synoviocytes from the FJ tissues were subjected to mechanical stress, ANGPTL2 expression and secretion were measured quantitatively using real-time quantitative reverse-transcription–polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA), respectively. Following ANGPTL2 administration in the FJ synoviocytes, anti-nuclear factor-κB (NF-κB) activation was investigated using immunocytochemistry, and IL-6 expression and secretion were assayed quantitatively with or without NF-κB inhibitor. Moreover, we assessed whether ANGPTL2-induced IL-6 modulates leucocyte recruitment in the degenerative process by focusing on the monocyte chemoattractant protein-1 (MCP-1) expression.

Results

ANGPTL2 and IL-6 were highly expressed in the hyperplastic FJ synovium samples. ANGPTL2 was co-expressed in both, fibroblast-like and macrophage-like synoviocytes. Further, the expression and secretion of ANGPTL2 in the FJ synoviocytes increased in response to stimulation by mechanical stretching. ANGPTL2 protein promoted the nuclear translocation of NF-κB and induced IL-6 expression and secretion in the FJ synoviocytes. This effect was reversed following treatment with NF-κB inhibitor. Furthermore, ANGPTL2-induced IL-6 upregulated the MCP-1 expression in the FJ synoviocytes.

Conclusions

Mechanical stress-induced ANGPTL2 promotes chronic inflammation in the FJ synovium by activating IL-6 secretion, leading to FJ degeneration and subsequent LSS.

Effects of Remnant Tissue Preservation on Tunnel Enlargement After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Hamstring Tendon

Background

The effects of remnant tissue preservation on tunnel enlargement after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction have not yet been established.

Hypothesis

The preservation of ACL remnant tissue may significantly reduce the degree and incidence of tunnel enlargement after anatomic double-bundle ACL reconstruction, while the remnant-preserving procedure may not significantly increase the incidence of tunnel coalition after surgery.

Study Design

Cohort study; Level of evidence, 2.

Methods

A total of 79 patients underwent anatomic double-bundle ACL reconstruction. Based on the Crain classification of ACL remnant tissue, 40 patients underwent the remnant-preserving procedure (group P), and the remaining 39 patients underwent the remnant-resecting procedure (group R). There were no differences between the 2 groups concerning all background factors, including preoperative knee instability and intraoperative tunnel positions. All patients were examined using computed tomography and a standard physical examination at 2 weeks and 1 year after surgery.

Results

During surgery, the femoral and tibial anteromedial (AM) tunnel sizes in both groups averaged 6.6 and 6.5 mm, respectively. The femoral and tibial posterolateral (PL) tunnel sizes in both groups averaged 6 and 6 mm, respectively. There were no differences in the intraoperative tunnel positions and tunnel sizes between groups. Concerning the femoral AM tunnel, the degree of tunnel enlargement in the oblique coronal and oblique axial views in group P was significantly less than that in group R (P = .0068 and .0323, respectively). Regarding the femoral AM tunnel cross-sectional area, the degree and incidence of tunnel enlargement in group P were significantly less than those in group R (P = .0086 and .0278, respectively). There were no significant differences in tunnel coalition between groups. In each group, there were no significant relationships between tunnel enlargement and each clinical outcome.

Conclusion

Remnant preservation in anatomic double-bundle ACL reconstruction reduced enlargement of the femoral AM tunnel and did not increase the incidence of tunnel coalition. This is one of the advantages of remnant-preserving ACL reconstruction.