An electrically conducting 3D coronene-based metal-organic framework.

A novel cubic mesoporous metal-organic framework (MOF), consisting of hexahydroxy-cata-hexabenzocoronene (c-HBC) and FeIII ions is presented. The highly crystalline and porous MOF features broad optical absorption over the whole visible and near infrared spectral regions. An electrical conductivity of 10-4 S cm-1 was measured on a pressed pellet.

Molecular nanoribbon gels.

Herein, we show that twisted molecular nanoribbons with as many as 322 atoms in the aromatic core are efficient gelators capable of self-assembling into ordered π-gels with morphologies and sol-gel transitions that vary with the length of the nanoribbon. In addition, the nanoribbon gels show a red fluorescence and also pseudoconductivity values in the same range as current state-of-the-art π-gels.

Non-invasive tests for clinically significant portal hypertension after HCV cure.

BACKGROUND & AIMS: Non-invasive tests (NITs) for clinically significant portal hypertension (CSPH; hepatic venous pressure gradient [HVPG] ≥10 mmHg) have predominantly been studied in patients with active HCV infection. Investigations after HCV cure are limited and have yielded conflicting results. We conducted a pooled analysis to determine the diagnostic/prognostic utility of liver stiffness measurement (LSM)/platelet count (PLT) in this setting. METHODS: A total of 418 patients with pre-treatment HVPG ≥6 mmHg who achieved sustained virological response (SVR) and underwent post-treatment HVPG measurement were assessed, of whom 324 (HVPG/NIT-cohort) also had paired data on pre-/post-treatment LSM/PLT. The derived LSM/PLT criteria were then validated against the direct endpoint decompensation in 755 patients with compensated advanced chronic liver disease (cACLD) with SVR (cACLD-validation-cohort). RESULTS: HVPG/NIT-cohort: Among patients with cACLD, the pre-/post-treatment prevalence of CSPH was 80%/54%. The correlation between LSM/HVPG increased from pre- to post-treatment (r = 0.45 vs. 0.60), while that of PLT/HVPG remained unchanged. For given LSM/PLT values, HVPG tended to be lower post- vs. pre-treatment, indicating the need for dedicated algorithms. Combining post-treatment LSM/PLT yielded a high diagnostic accuracy for post-treatment CSPH in cACLD (AUC 0.884; 95% CI 0.843-0.926). Post-treatment LSM <12 kPa & PLT >150 G/L excluded CSPH (sensitivity: 99.2%), while LSM ≥25 kPa was highly specific for CSPH (93.6%). cACLD-validation-cohort: the 3-year decompensation risk was 0% in the 42.5% of patients who met the LSM <12 kPa & PLT >150 G/L criteria. In patients with post-treatment LSM ≥25 kPa (prevalence: 16.8%), the 3-year decompensation risk was 9.6%, while it was 1.3% in those meeting none of the above criteria (prevalence: 40.7%). CONCLUSIONS: NITs can estimate the probability of CSPH after HCV cure and predict clinical outcomes. Patients with cACLD but LSM <12 kPa & PLT>150 G/L may be discharged from portal hypertension surveillance if no co-factors are present, while patients with LSM ≥25 kPa require surveillance/treatment. LAY SUMMARY: Measurement of liver stiffness by a specific ultrasound device and platelet count (a simple blood test) are broadly used for the non-invasive diagnosis of increased blood pressure in the veins leading to the liver, which drives the development of complications in patients with advanced liver disease. The results of our pooled analysis refute previous concerns that these tests are less accurate after the cure of hepatitis C virus (HCV) infection. We have developed diagnostic criteria that facilitate personalized management after HCV cure and allow for a de-escalation of care in a high proportion of patients, thereby decreasing disease burden.

A Crystalline 1D Dynamic Covalent Polymer.

The synthesis of crystalline one-dimensional polymers provides a fundamental understanding about the structure-property relationship in polymeric materials and allows the preparation of materials with enhanced thermal, mechanical, and conducting properties. However, the synthesis of crystalline one-dimensional polymers remains a challenge because polymers tend to adopt amorphous or semicrystalline phases. Herein, we report the synthesis of a crystalline one-dimensional polymer in solution by dynamic covalent chemistry. The structure of the polymer has been unambiguously confirmed by microcrystal electron diffraction that together with charge transport studies and theoretical calculations show how the π-stacked chains of the polymer generate optimal channels for charge transport.

Early predictors of corticosteroid response in acute severe autoimmune hepatitis: a nationwide multicenter study.

BACKGROUND AND AIMS: To assess whether corticosteroids improve prognosis in patients with AS-AIH, and to identify factors at therapy initiation and during therapy predictive of the response to corticosteroids. METHODS: This was a retrospective cohort study including all patients with AS-AIH admitted to 13 tertiary centres from January 2002 to January 2019. The composite primary outcome was death or liver transplantation within 90 days of admission. Kaplan-Meier and Cox regression methods were used for data analysis. RESULTS: Of 242 consecutive patients enrolled (mean age [SD] 49.7 [16.8] years), 203 received corticosteroids. Overall 90-day transplant-free survival was 61.6% (95% confidence interval [CI] 55.4-67.7). Corticosteroids reduced the risk of a poor outcome (adjusted hazard ratio [HR] 0.25; 95% CI 0.2-0.4), but this treatment failed in 30.5%. An internally validated nomogram composed of older age, MELD, encephalopathy and ascites at the initiation of corticosteroids accurately predicted the response (C-index 0.82; [95% CI 0.8-0.9]). In responders, MELD significantly improved from days 3 to 14 but remained unchanged in non-responders. MELD on day 7 with a cut-off of 25 (sensitivity 62.5%[95% CI: 47.0-75.8]; specificity 95.2% [95% CI: 89.9-97.8]) was the best univariate predictor of the response. Prolonging corticosteroids did not increase the overall infection risk (adjusted HR 0.75; 95% CI 0.3-2.1). CONCLUSION: Older patients with high MELD, encephalopathy or ascites at steroid therapy initiation and during treatment are unlikely to show a favourable response and so prolonged therapy in these patients, especially if they are transplantation candidates, should be avoided.

Observing polymerization in 2D dynamic covalent polymers.

The quality of crystalline two-dimensional (2D) polymers1-6 is intimately related to the elusive polymerization and crystallization processes. Understanding the mechanism of such processes at the (sub)molecular level is crucial to improve predictive synthesis and to tailor material properties for applications in catalysis7-10 and (opto)electronics11,12, among others13-18. We characterize a model boroxine 2D dynamic covalent polymer, by using in situ scanning tunnelling microscopy, to unveil both qualitative and quantitative details of the nucleation-elongation processes in real time and under ambient conditions. Sequential data analysis enables observation of the amorphous-to-crystalline transition, the time-dependent evolution of nuclei, the existence of 'non-classical' crystallization pathways and, importantly, the experimental determination of essential crystallization parameters with excellent accuracy, including critical nucleus size, nucleation rate and growth rate. The experimental data have been further rationalized by atomistic computer models, which, taken together, provide a detailed picture of the dynamic on-surface polymerization process. Furthermore, we show how 2D crystal growth can be affected by abnormal grain growth. This finding provides support for the use of abnormal grain growth (a typical phenomenon in metallic and ceramic systems) to convert a polycrystalline structure into a single crystal in organic and 2D material systems.

Nonplanar Rhombus and Kagome 2D Covalent Organic Frameworks from Distorted Aromatics for Electrical Conduction.

Two-dimensional (2D) covalent organic frameworks (COFs) are an emerging class of promising 2D materials with high crystallinity and tunable structures. However, the low electrical conductivity impedes their applications in electronics and optoelectronics. Integrating large π-conjugated building blocks into 2D lattices to enhance efficient π-stacking and chemical doping is an effective way to improve the conductivity of 2D COFs. Herein, two nonplanar 2D COFs with kagome (DHP-COF) and rhombus (c-HBC-COF) lattices have been designed and synthesized from distorted aromatics with different π-conjugated structures (flexible and rigid structure, respectively). DHP-COF shows a highly distorted 2D lattice that hampers stacking, consequently limiting its charge carrier transport properties. Conversely, c-HBC-COF, with distorted although concave-convex self-complementary nodes, shows a less distorted 2D lattice that does not interfere with interlayer π-stacking. Employing time- and frequency-resolved terahertz spectroscopy, we unveil a high charge-carrier mobility up to 44 cm2 V-1 s-1, among the highest reported for 2D COFs.

Understanding charge transport in wavy 2D covalent organic frameworks.

Understanding charge transport in 2D covalent organic frameworks is crucial to increase their performance. Herein a new wavy 2D covalent organic framework has been designed, synthesized and studied to shine light on the structural factors that dominate charge transport.

π-Interpenetrated 3D Covalent Organic Frameworks from Distorted Polycyclic Aromatic Hydrocarbons.

Three-dimensional covalent organic frameworks (3D COFs) with a pcu topology have been obtained from distorted polycyclic aromatic hydrocarbons acting as triangular antiprismatic (D3d ) nodes. Such 3D COFs are six-fold interpenetrated as the result of interframework π-stacking, which enable charge transport properties that are not expected for 3D COFs.

Structural Approaches to Control Interlayer Interactions in 2D Covalent Organic Frameworks.

The ability to design and synthesize monomers can affect fundamental aspects in 2D covalent organic frameworks, such as dimensionality, topology, and pore size. Besides this, the structure of the monomers can also affect interlayer interactions, which provide an additional means to influence crystallinity, layer arrangement, interlayer distances, and exfoliability. Herein, some of the effects that the structure of monomers can have on the interlayer interactions in 2D covalent organic frameworks and related materials are illustrated.

Real-Time Molecular-Scale Imaging of Dynamic Network Switching between Covalent Organic Frameworks.

The in situ on-surface conversion process from boroxine-linked covalent organic frameworks (COFs) to boronate ester-linked COFs is triggered and catalyzed at room temperature by an electric field and monitored with scanning tunneling microscopy (STM). The adaptive behavior within the generated dynamic covalent libraries (DCLs) was revealed, providing in-depth understanding of the dynamic network switching process.

Anatomy of On-Surface Synthesized Boroxine Two-Dimensional Polymers.

Synthetic two-dimensional polymers (2DPs) obtained from well-defined monomers via bottom-up fabrication strategies are promising materials that can extend the realm of inorganic 2D materials. The on-surface synthesis of such 2DPs is particularly popular, however the pathway complexity in the growth of such films formed on solid surfaces is poorly understood. In this contribution, we present a straightforward experimental protocol which allows the synthesis of large-area, defect-free 2DPs based on boroxine linkages at room temperature. We focus on unravelling the multiple pathways available to the polymerizing system for the spatial extension of the covalent bonds. Besides the anticipated 2DP, the system can evolve into self-assembled monolayers of partially fused monodisperse reaction products that are difficult to isolate by conventional synthetic methods or remain in the monomeric state. The access to each pathway can be controlled via monomer concentration and the choice of the solvent. Most importantly, the unpolymerized systems do not evolve into the corresponding 2DP upon annealing, indicating the presence of strong kinetic traps. Using high-resolution scanning tunneling microscopy, we show reversibility in the polymerization process where the attachment and the detachment of monomers to 2DP crystallites could be monitored as a function of time. Finally, we show that the way the 2DP grows depends on the choice of the solvent. Using UV-vis absorption and emission spectroscopy, we reveal that the dominant pathway for 2DP growth is via in-plane self-condensation of the monomers, whereas in the case of an aprotic solvent, the favored growth mode is via π stacking of the monomers.

A Wavy Two-Dimensional Covalent Organic Framework from Core-Twisted Polycyclic Aromatic Hydrocarbons.

A high degree of crystallinity is an essential aspect in two-dimensional covalent organic frameworks, as many properties depend strongly on the structural arrangement of the different layers and their constituents. We introduce herein a new design strategy based on core-twisted polycyclic aromatic hydrocarbon as rigid nodes that give rise to a two-dimensional covalent organic framework with a wavy honeycomb (chairlike) lattice. The concave-convex self-complementarity of the wavy two-dimensional lattice guides the stacking of framework layers into a highly stable and ordered covalent organic framework that allows a full 3D analysis by transmission electron microscopy revealing its chairlike honeycomb facets and aligned mesoporous channels. Remarkably, the waviness of the framework does not disrupt the interlayer π-π stacking that shows charge transporting properties similar to those of planar covalent organic frameworks. The implementation of core-twisted aromatics as building blocks for covalent organic frameworks brings new possibilities in the design of highly ordered organic materials.

Management of betablocked patients after sustained virological response in hepatitis C cirrhosis.

BACKGROUND: Current guidelines do not address the post-sustained virological response management of patients with baseline hepatitis C virus (HCV) cirrhosis and oesophageal varices taking betablockers as primary or secondary prophylaxis of variceal bleeding. We hypothesized that in some of these patients portal hypertension drops below the bleeding threshold after sustained virological response, making definitive discontinuation of the betablockers a safe option. AIM: To assess the evolution of portal hypertension, associated factors, non-invasive assessment, and risk of stopping betablockers in this population. METHODS: Inclusion criteria were age > 18 years, HCV cirrhosis (diagnosed by liver biopsy or transient elastography > 14 kPa), sustained virological response after direct-acting antivirals, and baseline oesophageal varices under stable, long-term treatment with betablockers as primary or secondary bleeding prophylaxis. Main exclusion criteria were prehepatic portal hypertension, isolated gastric varices, and concomitant liver disease. Blood tests, transient elastography, and upper gastrointestinal endoscopy were performed. Hepatic venous pressure gradient (HVPG) was measured five days after stopping betablockers. Betablockers could be stopped permanently if gradient was < 12 mmHg, at the discretion of the attending physician. RESULTS: Sample comprised 33 patients under treatment with propranolol or carvedilol: median age 64 years, men 54.5%, median Model for End-Stage Liver Disease (MELD) score 9, Child-Pugh score A 77%, median platelets 77.000 × 103/µL, median albumin 3.9 g/dL, median baseline transient elastography 24.8 kPa, 88% of patients received primary prophylaxis. Median time from end of antivirals to gradient was 67 wk. Venous pressure gradient was < 12 mmHg in 13 patients (39.4%). In univariate analysis the only associated factor was a MELD score decrease from baseline. On endoscopy, variceal size regressed in 19/27 patients (70%), although gradient was ≥ 12 mmHg in 12/19 patients. The elastography area under receiver operating characteristic for HVPG ≥ 12 mmHg was 0.62. Betablockers were stopped permanently in 10/13 patients with gradient < 12 mmHg, with no bleeding episodes after a median follow-up of 68 wk. CONCLUSION: Portal hypertension dropped below the bleeding threshold in 39% of patients more than one year after antiviral treatment. Endoscopy and transient elastography are inaccurate for reliable detection of this change. Stopping betablockers permanently seems uneventful in patients with a gradient < 12 mmHg.

Isolation and Characterization of the Unexpected 1- n-Octyloxyperopyrene: A Solution-Processable p-Type Organic Semiconductor.

The synthesis and optical, electrochemical, thermal, and electrical characterization of a new and unexpected 1- n-octyloxyperopyrene is reported. The structure of 1- n-octyloxyperopyrene has been unambiguously established by single-crystal X-ray diffraction. The solubility of this polycyclic aromatic hydrocarbon, endowed by the alkoxy substituent, allows the fabrication of thin-film field-effect transistors by liquid deposition methods. These devices show hole mobilities up to 1.61 × 10-3 cm2 V-1 s-1.

Three dimensional nanoscale analysis reveals aperiodic mesopores in a covalent organic framework and conjugated microporous polymer.

The integrated analytical approach developed in this study offers a powerful methodology for the structural characterisation of complex molecular nanomaterials. Structures of a covalent organic framework based on boronate esters (COF-5) and a conjugated microporous polymer (Aza-CMP) have been investigated by a combination of several electron microscopy techniques elucidating the three-dimensional topology of the complex polycrystalline (COF) and non-crystalline (CMP) materials. Unexpected, aperiodic mesoporous channels of 20-50 nm in diameter were found to be penetrating the COF and CMP particles, which cannot be detected by X-ray diffraction techniques. The mesopores appear to be stable under a range of different conditions and accessible to gas molecules, exhibiting a particular bonding capability with CO2 in the case of the CMP. The mesoporosity is unrelated to the intrinsic chemical structures of the COF or CMP but rather it reflects the mechanisms of polymer particle formation in a polycondensation reaction. The mesopores may be templated by clusters of solvent molecules during the COF or CMP synthesis, leaving cavities within the polymer particles. The unexpected mesoporosity discovered in COF and CMP materials begs for re-assessment of the nature of framework materials and may open new opportunities for applications of these molecular materials in gas sorption or catalysis.

Readily Processable Hole-Transporting Peropyrene Gels.

The development of organic electronics requires scalable solution-processing methods that enable the fabrication of electronic devices over large areas at low cost. The preparation of peropyrene gels constituted of 3D networks of entangled 1D ribbon-like fibrils that extend over the µm scale are now reported. OFETs were easily fabricated by depositing the gels in the sol state over bottom-gate bottom-contact transistors and by allowing its gelation thereafter. Electrical characterisation of such field-effect transistors shows a good balance between processability and performance with hole mobilities that are two orders of magnitude higher than those observed in thin films obtained from non-gelating solvents under the same conditions.

Self-Assembled α-Cyanostilbenes for Advanced Functional Materials.

In the specific context of condensed media, the significant and increasing recent interest in the α-cyanostilbene (CS) motif [ArCHC(CN)Ar] is relevant. These compounds have shown remarkable optical features in addition to interesting electrical properties, and hence they are recognized as very suitable and versatile options for the development of functional materials. This progress report is focused on current and future use of CS structures and molecular assemblies with the aim of exploring and developing for the next generations of functional materials. A critical selection of illustrative materials that contain the CS motif, including relevant subfamilies such as the dicyanodistyrylbenzene and 2,3,3-triphenylacrylonitrile shows how, driven by the self-assembly of CS blocks, a variety of properties, effects, and possibilities for practical applications can be offered to the scientific community, through different rational routes for the elaboration of advanced materials. A survey is provided on the research efforts directed toward promoting the self-assembly of the solid state (polycrystalline solids, thin films, and single crystals), liquid crystals, nanostructures, and gels with multistimuli responsiveness, and applications for sensors, organic light-emitting diodes, organic field effect transistors, organic lasers, solar cells, or bioimaging purposes.

Synthesis and Properties of a Twisted and Stable Tetracyano-Substituted Tetrabenzoheptacene.

An approach for the synthesis of pyrene-fused acenes that allows the introduction of electron-withdrawing cyano groups in key positions that simultaneously (i) induce twists in the aromatic framework and (ii) stabilize the LUMO level is reported. This combination of steric and electronic features provide a twisted, stable, and n-type tetrabenzoheptacene as confirmed by a combination of theoretical calculations and optical, electrochemical, thermal, and electrical characterization.

Photoresponsive Cyanostilbene Bent-Core Liquid Crystals as New Materials with Light-Driven Modulated Polarization.

Two isomeric cyanostilbene photoswitchable bent-core mesogens with polar liquid crystal phases in which macroscopic polarization and luminescence can be light-modulated are introduced. Z/E isomerization or [2+2] cycloaddition photochemical processes occur depending on the chemical structure, which make the compounds very innovative multifunctional advanced materials.