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Interactions of Ni(0) and thiophene–benzothiadiazole–thiophene (TBT) units during the Kumada catalyst transfer polycondensation (KCTP) of 2-chloromagnesio-5-bromo-3-hexylthiophene (1) are investigated. Monofunctional TBT initiator precursors are used for the external initiation of KCTP, and the mechanism of initiator activation and polymerization is elucidated using NMR and MALDI-ToF MS. We find that the activation of the TBT-bromide initiator precursor using nickel–diethylbipyridine (NiEt2bipy) occurs via a two-step pathway, in which NiEt2bipy coordinates to benzothiadiazole (B) first, followed by the elimination of butane and oxidative addition of liberated Ni(0)bipy into the terminal TBT–Br bond. It is shown that the B unit traps Ni(0) during the KCTP of 1, which results in significant termination, as derived from the degree of bromine-terminated chains. The ability of B units to trap Ni(0) is further illustrated by using a symmetric bifunctional Br-TBT-Br initiator precursor for the KCTP of 1, during which Ni(0) is not able to “ring walk” over the B unit to initiate polymerization at the other end of the chain. These results are important for the design of well-defined and electronically end-functionalized conjugated polymers, but also for understanding termination mechanisms in KCTP in general. [ABSTRACT FROM AUTHOR]

The construction of multiple heptagonal rings in nanographene is the key step for obtaining exotic carbon nanostructures with a negative curvature and intriguing properties. Herein, a novel saddle-shaped nanographene ( 1 ) with four embedded heptagons is synthesized via a highly efficient one-shot Scholl reaction from a predesigned oligophenylene precursor. Notably, a quadruple [6]helicene intermediate was also obtained and isolated by controlling the Scholl reaction conditions. Interestingly, the single crystal structures of 1 display a saddle geometry induced by the four embedded heptagons, resulting in a deep curvature with a width of 16.5 Å and a depth of 8.0 Å. Theoretical calculations at the molecular level suggest a weak antiaromatic character of the heptagons in 1 . Remarkably, compound 1 exhibits dual fluorescence from S 1 and S 2 . The deep-saddle-shaped geometry in 1 defines host-guest interactions with fullerenes, which were explored in titration experiments and by theoretical methods. The resulting 1@C 60 are stable and are subject to an electron transfer from photoexcited 1 to C 60 . Our current study underscores the influence of heptagon rings on the photophysical, self-assembly, and electron-donating properties of NGs.

Background: Post-stroke fatigue (PSF) affects 50% of stroke survivors. Current guidance on management of this condition is limited., Aims: This systematic review and meta-analysis aimed to identify and analyze all randomized clinical trials (RCTs) of non-pharmacological interventions for the treatment of PSF., Summary of Review: Six electronic databases were searched from inception to January 2023 for English-language RCTs investigating the efficacy of non-pharmacological interventions versus passive controls in patients with PSF. The primary outcome was fatigue severity at the end of the intervention. The Cochrane risk-of-bias (ROB)2 tool was used to assess evidence quality. A total of 7990 records were retrieved, 333 studies were scrutinized, and 13 completed RCTs (484 participants) were included. Interventions included psychological therapies, physical therapies, and brain stimulation. Nine studies provided sufficient data for meta-analysis, of which seven also had follow-up data. Fatigue severity was lower in the intervention groups at the end of the intervention compared with control (participants = 310, standardized mean difference (SMD) = -0.57, 95% confidence intervals (CIs) (-0.87 to -0.28)) and at follow-up (participants = 112, SMD = -0.36, 95% CIs (-0.83 to 0.10)). Certainty in the effect estimate was downgraded to low for a serious ROB and imprecision. Subgroup analysis revealed significant benefits with physical therapy and brain stimulation but not psychological therapies, though sample sizes were low., Conclusion: Non-pharmacological interventions improved fatigue but the quality of evidence was low. Further RCTs are needed for PSF management., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Helical nanographenes with high quantum yields and strong chiroptical responses are pivotal for developing circularly polarized luminescence (CPL) materials. Here, we present the successful synthesis of novel π-extended double [7]helicenes (ED7Hs) where two helicene units are fused at the meta- or para-position of the middle benzene ring, respectively, as the structural isomers of the reported ortho-fused ED7H. The structural geometry of these ED7Hs is clearly characterized by single-crystal X-ray analysis. Notably, this class of ED7Hs exhibits bright luminescence with high quantum yields exceeding 40 %. Through geometric regulation of two embedded [7]helicene units from ortho-, meta- to para-position, these ED7Hs display exceptional amplification in chiroptical responses. This enhancement is evident in a remarkable approximate fivefold increase in the absorbance and luminescence dissymmetry factors (g abs and g lum ), respectively, along with a boosted CPL brightness up to 176 M -1  cm -1 , surpassing the performance of most helicene-based chiral NGs. Furthermore, DFT calculations elucidate that the geometric adjustment of two [7]helicene units allows the precise alignment of electric and magnetic transition dipole moments, leading to the observed enhancement of their chiroptical responses. This study offers an effective strategy for magnifying the CPL performance in chiral NGs, promoting their expanded application as CPL emitters., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Computed tomography (CT) imaging of the thorax is widely used for the detection and monitoring of pulmonary embolism (PE). However, CT images can contain artifacts due to the acquisition or the processes involved in image reconstruction. Radiologists often have to distinguish between such artifacts and actual PEs. We provide a proof of concept in the form of a scalable hypothesis testing method for CT, to enable quantifying uncertainty of possible PEs. In particular, we introduce a Bayesian Framework to quantify the uncertainty of an observed compact structure that can be identified as a PE. We assess the ability of the method to operate under high-noise environments and with insufficient data., (© The Author(s) 2024. Published by Oxford University Press on behalf of National Academy of Sciences.)

Due to some useful mechanical, dynamic, and dielectric properties along with the ease of processing and forming, liquid rubbers are ideal materials for fabricating dielectric elastomer actuators in various configurations and for many potential applications ranging from automation to automobile and medical industry. In this study, we present a cross-linkable liquid rubber composition where amine-catalyzed esterification reactions lead to the formation of a network structure based on anhydride functional isoprene rubber, carboxyl-terminated nitrile-butadiene rubber, and epoxy end-capped prepolymers. The success of this intricate network formation procedure was verified by HR-MAS NMR spectroscopy. The new isoprene-based elastomeric material exhibits actuation-relevant attributes including a low elastic modulus of 0.45 MPa, soft response to an applied load up to a large deformation of 300%, and a dielectric constant value (2.6) higher than the conventional Elastosil silicone (2.2). A dot actuator comprising of an isoprene dielectric elastomer film in unstretched state and carbon paste electrodes was fabricated that demonstrated an electrode deformation of 0.63%, which is nearly twice as high as for the commercial Elastosil 2030 film (∼0.30%) at 5 kV. Compared to the Elastosil silicone film, the enhanced performance is attributed to the low modulus and high dielectric constant value of the new isoprene elastomer., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Graphene nanoribbons (GNRs) have garnered significant interest due to their highly customizable physicochemical properties and potential utility in nanoelectronics. Besides controlling widths and edge structures, the inclusion of chirality in GNRs brings another dimension for fine-tuning their optoelectronic properties, but related studies remain elusive owing to the absence of feasible synthetic strategies. Here, we demonstrate a novel class of cove-edged chiral GNRs ( CcGNRs ) with a tunable chiral vector ( n , m ). Notably, the bandgap and effective mass of ( n ,2)-CcGNR show a distinct positive correlation with the increasing value of n , as indicated by theory. Within this GNR family, two representative members, namely, (4,2)-CcGNR and (6,2)-CcGNR , are successfully synthesized. Both CcGNRs exhibit prominently curved geometries arising from the incorporated [4]helicene motifs along their peripheries, as also evidenced by the single-crystal structures of the two respective model compounds ( 1 and 2 ). The chemical identities and optoelectronic properties of (4,2)- and (6,2)-CcGNRs are comprehensively investigated via a combination of IR, Raman, solid-state NMR, UV-vis, and THz spectroscopies as well as theoretical calculations. In line with theoretical expectation, the obtained (6,2)-CcGNR possesses a low optical bandgap of 1.37 eV along with charge carrier mobility of ∼8 cm 2 V -1 s -1 , whereas (4,2)-CcGNR exhibits a narrower bandgap of 1.26 eV with increased mobility of ∼14 cm 2 V -1 s -1 . This work opens up a new avenue to precisely engineer the bandgap and carrier mobility of GNRs by manipulating their chiral vector.

Helical nanographenes (NGs) have attracted increasing attention recently because of their intrinsic chirality and exotic chiroptical properties. However, the efficient synthesis of extended helical NGs featuring a multilayer topology is still underdeveloped, and their layer-dependent chiroptical properties remain elusive. In this study, we demonstrate a modular synthetic strategy to construct a series of novel helical NGs ( 1 - 3 ) with a multilayer topology through a consecutive Diels-Alder reaction and regioselective cyclodehydrogenation from the readily accessible phenanthrene-based precursors bearing ethynyl groups. The resultant NGs exhibit bilayer, trilayer, and tetralayer structures with elongated π extension and rigid helical backbones, as unambiguously confirmed by single-crystal X-ray or electron diffraction analysis. We find that the photophysical properties of these helical NGs are notably influenced by the degree of π extension, which varies with the number of layers, leading to obvious redshifted absorption, a fast rising molar extinction coefficient (ε), and markedly boosted fluorescence quantum yield (Φ f ). Moreover, the embedded [7]helicene subunits in these NGs result in stable chirality, enabling both chiral resolution and exploration of their layer-dependent chiroptical properties. Profiting from the good alignment of electric and magnetic dipole moments determined by the multilayer structure, the resultant NGs exhibit excellent circular dichroism and circularly polarized luminescence response with unprecedented high CPL brightness up to 168 M -1 cm -1 , rendering them promising candidates for CPL emitters.

Efficient organic electronic devices are fabricated from both small molecules and disperse polymers, but materials with characteristics in between remain largely unexplored. Here, we present a gram-scale synthesis for a series of discrete n-type oligomers comprising alternating naphthalene diimide (NDI) and bithiophene (T2). Using C-H activation, discrete oligomers of type T2-(NDI-T2) n ( n ≤ 7) and persistence lengths up to ∼10 nm are made. The absence of protection/deprotection reactions and the mechanistic nature of Pd-catalyzed C-H activation allow one to produce symmetrically terminated species almost exclusively, which is key to the fast preparation, high yields, and the general success of the reaction pathway. The reaction scope includes different thiophene-based monomers, end-capping to yield NDI-(T2-NDI) n ( n ≤ 8), and branching at T2 units by nonselective C-H activation under certain conditions. We show how the optical, electronic, thermal, and structural properties depend on oligomer length along with a comparison to the disperse, polymeric analogue PNDIT2. From theory and experiments, we find that the molecular energy levels are not affected by chain length resulting from the strong donor-acceptor system. Absorption maxima saturate for n = 4 in vacuum and for n = 8 in solution. Linear oligomers T2-(NDI-T2) n are highly crystalline with large melting enthalpies up to 33 J/g; NDI-terminated oligomers show reduced crystallinity, stronger supercooling, and more phase transitions. Branched oligomers and those with bulky thiophene comonomers are amorphous. Large oligomers exhibit similar packing characteristics compared to PNDIT2, making these oligomers ideal models to study length-structure-function relationships at constant energy levels.

Introduction Increasing rectal size is associated with increased artefacts on magnetic resonance imaging (MRI) of the prostate and has the potential to degrade image quality. The objective of this study was to analyse the effect of oral laxative medication on rectal distension and image quality in prostate MRI. Methods Eighty patients prospectively received either 15 mg of oral senna (laxative group) or no medication (control group). Patients underwent prostate MRI according to standard local protocol and seven rectal dimensions on axial and sagittal images were measured. A subjective assessment of rectal distension was also made using a five-point Likert scale. Finally, artefacts on diffusion-weighted sequences were assessed using a four-point Likert scale. Results There was a small reduction in rectal diameter on sagittal images in the laxative group compared to the control group, with mean diameters of 27.1 mm and 30.0 mm respectively, p=0.02. There was no significant difference in rectal measurements of anteroposterior diameter, transverse diameter, or rectal circumference on axial imaging. Subjective scoring also demonstrated no significant difference in diffusion-weighted imaging quality between the laxative group and control group, p=0.82. Conclusion Bowel preparation with the oral laxative, senna, provided only a marginal decrease in rectal distension on one measure and no reduction in artefacts on diffusion-weighted sequences. The findings of this study do not support the routine use of this medication in patients undergoing prostate MRI., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Foley et al.)

Objectives: Whole-body single photon emission computed tomography/computed tomography (WB-SPECT/CT) is useful for diagnosing bone metastases. When performed on a dual-headed gamma camera, this may cover from clavicles to proximal femurs due to time constraints. In contrast, the novel 360 o cadmium-zinc-telluride scanner can perform WB-SPECT/CT (from vertex to toes) in approximately 20 min. The aim was to assess the prevalence of additional findings above the clavicles and below the lesser trochanters and the prevalence of incidental findings in the CT component., Methods: Retrospective study of 117 WB-SPECT/CT scans for oncological bone assessment over a 4-month-period. Scan analysis was performed by two independent experienced radionuclide radiologists., Results: The male:female ratio was 71:46 and the mean patient age was 68 years. The primary malignancies were predominantly prostate 65/117 (55.6%) and breast 40/117 (34.2%). There were additional findings of malignancy above the clavicles in 16/116 scans (13.8%) and below the lesser trochanters in 16/117 scans (13.7%). Two cases in the 'above the clavicles' group were suspected solitary metastases, whereas four cases in the 'below lesser trochanters' group were bone metastases at risk of pathological fracture. Incidental findings of clinical significance included suspected new malignancy in 11/117 (9.4%)., Conclusion: A WB-SPECT/CT (from vertex to toes) oncological bone protocol is useful for the detection of additional findings of clinical significance above the clavicles and below the lesser trochanters. Reviewing and reporting the CT findings in SPECT/CT is important., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.)

The precision synthesis of helical bilayer nanographenes (NGs) with new topology is of substantial interest because of their exotic physicochemical properties. However, helical bilayer NGs bearing non-hexagonal rings remain synthetically challenging. Here we present the efficient synthesis of the first helical bilayer nonbenzenoid nanographene (HBNG1) from a tailor-made azulene-embedded precursor, which contains a novel [10]helicene backbone with two embedded heptagons. Single-crystal X-ray analysis reveals its highly twisted bilayer geometry with a record small interlayer distance of 3.2 Å among the reported helical bilayer NGs. Notably, the close interlayer distance between the two layers offers intramolecular through-space conjugation as revealed by in situ spectroelectrochemistry studies together with DFT simulations. Furthermore, the chiroptical properties of the P/M enantiomers of HBNG1 are also evaluated by circular dichroism and circularly polarized luminescence., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The impact of phosphorus-containing flame retardants (FR) on rigid polyisocyanurate (PIR) foams is studied by systematic variation of the chemical structure of the FR, including non-NCO-reactive and NCO-reactive dibenzo[d,f][1,3,2]dioxaphosphepine 6-oxide (BPPO)- and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-containing compounds, among them a number of compounds not reported so far. These PIR foams are compared with PIR foams without FR and with standard FRs with respect to foam properties, thermal decomposition, and fire behavior. Although BPPO and DOPO differ by just one oxygen atom, the impact on the FR properties is very significant: when the FR is a filler or a dangling (dead) end in the PIR polymer network, DOPO is more effective than BPPO. When the FR is a subunit of a diol and it is fully incorporated in the PIR network, BPPO delivers superior results.

Curved graphene nanoribbons (GNRs) with hybrid edge structures have recently attracted increasing attention due to their unique band structures and electronic properties as a result of their nonplanar conformation. This work reports the solution synthesis of a long and curved multi-edged GNR (cMGNR) with unprecedented cove-armchair-gulf edge structures. The synthesis involves an efficient A 2 B 2 -type Diels-Alder polymerization between a diethynyl-substituted prefused bichrysene monomer (3b) and a dicyclopenta[e,l]pyrene-5,11-dione derivative (6) followed by FeCl 3 -mediated Scholl oxidative cyclodehydrogenation of the obtained polyarylenes (P1). Model compounds 1a and 1b are first synthesized to examine the suitability and efficiency of the corresponding polymers for the Scholl reaction. The successful formation of cMGNR from polymer P1 bearing prefused bichrysene units is confirmed by FTIR, Raman, and solid-state NMR analyses. The cove-edge structure of the cMGNR imparts the ribbon with a unique nonplanar conformation as revealed by density functional theory (DFT) simulation, which effectively enhances its dispersibility in solution. The cMGNR has a narrow optical bandgap of 1.61 eV, as estimated from the UV-vis absorption spectrum, which is among the family of low-bandgap solution-synthesized GNRs. Moreover, the cMGNR exhibits a carrier mobility of ≈2 cm 2 V -1 s -1 inferred from contact-free terahertz spectroscopy., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Open-shell non-alternant polycyclic hydrocarbons (PHs) are attracting increasing attention due to their promising applications in organic spintronics and quantum computing. Herein we report the synthesis of three cyclohepta[def]fluorene-based diradicaloids (1-3), by fusion of benzo rings on its periphery for the thermodynamic stabilization, as evidenced by multiple characterization techniques. Remarkably, all of them display a very narrow optical energy gap (E g opt =11.7-33.3 h). More importantly, this new type of diradicaloids possess a low-lying triplet state with an extremely small singlet-triplet energy gap, as low as 0.002 kcal mol 1/2 =11.7-33.3 h). More importantly, this new type of diradicaloids possess a low-lying triplet state with an extremely small singlet-triplet energy gap, as low as 0.002 kcal mol -1 , with a clear dependence on the molecular size. This family of compounds thus offers a new route to create non-alternant open-shell PHs with high-spin ground states, and opens up novel possibilities and insights into understanding the structure-property relationships., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Anti-(ds)-DNA antibodies are the serological hallmark of Systemic Lupus Erythematosus (SLE). They assemble in the bloodstream with (ds)-DNA, forming immunocomplexes, which spread all over the body causing, among the other symptoms, lupic glomerulonephritis. Pathological manifestations of the disease may be reduced by destabilizing or inhibiting the formation of the immunocomplexes. In this respect, glycodendrimers showed peculiar interacting abilities towards this kind of biomolecule. Various generations of open-shell maltose-decorated poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI) dendrimers and two oligopeptides with different polyethylene glycol units were synthesized and characterized, and then tested for their anti-SLE activity. The activity of glycodendrimers and oligopeptides was evaluated in human plasma from patients with SLE, compared to healthy plasma, by means of an enzyme-linked immunosorbent assay (ELISA), and electron paramagnetic resonance (EPR) characterization using spin-label and spin-probe techniques. Different strategies for the immunocomplex formation were tested. The results show that both kinds of glycodendrimers and oligopeptides inhibited the formation of immunocomplexes. Also, a partial breakdown of preformed immunocomplexes was observed. Both ELISA and EPR analyses indicated a better activity of glycodendrimers compared to oligopeptides, the 3 rd generation PPI dendrimer being the most promising against SLE. This study highlights the possibility to develop a new class of dendritic therapeutics for the treatment of Lupus in pre-clinical studies.

Aims: To explore whether the novel 360° gamma camera design of VERITON-CT adversely affects the rate of scan non-completion due to claustrophobia or other patient experience factors, when compared to a standard dual-headed gamma camera. Methods: Single centre prospective study of all nuclear medicine studies on either of two gamma cameras; the VERITON-CT (Spectrum Dynamics Medical) and Discovery NM/CT 670 (GE Healthcare). It was recorded whether the patient had completed the scan as protocoled or, due to claustrophobia, had a shortened scan or no scan. The patients were also offered a patient experience questionnaire, with domains of comfort, scan time, scan noise and claustrophobia assessed using a five-point Likert scale. Results: Over a four-month period, there were 296 patients scanned on the Discovery scanner and 274 patients scanned on the VERITON-CT scanner. There was a scan non-completion rate, due to claustrophobia, of 1.35 % for the Discovery and 1.46 % for the VERITON-CT scanner. 354/570 (62%) of all patients involved returned their questionnaires. There was no statistical difference between the responses for comfort, scan time, scan noise and feelings of claustrophobia. Conclusion: The study provides evidence that the novel 360° gamma camera design of VERITON-CT does not lead to a significantly increased scan failure rate due to claustrophobia and there is no change in the subjective experience for patients., (Copyright © 2021 by the Society of Nuclear Medicine and Molecular Imaging, Inc.)

n-peri-Acenes (n-PAs) have gained interest as model systems of zigzag-edged graphene nanoribbons for potential applications in nanoelectronics and spintronics. However, the synthesis of n-PAs larger than peri-tetracene remains challenging because of their intrinsic open-shell character and high reactivity. Presented here is the synthesis of a hitherto unknown n-PA, that is, peri-heptacene (7-PA), in which the reactive zigzag edges are kinetically protected with eight 4-tBu-C 6 H 4 groups. The formation of 7-PA is validated by high-resolution mass spectrometry and in situ FT-Raman spectroscopy. 7-PA displays a narrow optical energy gap of 1.01 eV and exhibits persistent stability (t 1/2 ≈25 min) under inert conditions. Moreover, electron-spin resonance measurements and theoretical studies reveal that 7-PA exhibits an open-shell feature and a significant tetraradical character. This strategy could be considered a modular approach for the construction of next-generation (3 N+1)-PAs (where N≥3)., (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

In this work, we describe the synthesis and characterization of three novel sulfur-doped nanographenes (NGs) ( 1-3 ) containing multiple subhelicenes, including carbo[4]helicenes, thieno[4]helicenes, carbo[5]helicenes, and thieno[5]helicenes. Density functional theory calculations reveal that the helicene substructures in 1-3 possess dihedral angles from 15° to 34°. The optical energy gaps of 1-3 are estimated to be 2.67, 2.45, and 2.30 eV, respectively. These three sulfur-doped NGs show enlarged energy gaps compared to those of their pristine carbon analogues.

Defects have been observed in graphene and are expected to play a key role in its optical, electronic, and magnetic properties. However, because most of the studies focused on the structural characterization, the implications of topological defects on the physicochemical properties of graphene remain poorly understood. Here, we demonstrate a bottom-up synthesis of three novel nanographenes ( 1 - 3 ) with well-defined defects in which seven-five-seven (7-5-7)-membered rings were introduced to their sp 2 carbon frameworks. From the X-ray crystallographic analysis, compound 1 adopts a nearly planar structure. Compound 2 , with an additional five-membered ring compared to 1 , possesses a slightly saddle-shaped geometry. Compound 3 , which can be regarded as the "head-to-head" fusion of 1 with two bonds, features two saddles connected together. The resultant defective nanographenes 1 - 3 were well-investigated by UV-vis absorption, cyclic voltammetry, and time-resolved absorption spectra and further corroborated by density functional theory (DFT) calculations. Detailed experimental and theoretical investigations elucidate that these three nanographenes 1 - 3 exhibit an anti-aromatic character in their ground states and display a high stability under ambient conditions, which contrast with the reported unstable biradicaloid nanographenes that contain heptagons. Our work reported herein offers insights into the understanding of structure-related properties and enables the control of the electronic structures of expanded nanographenes with atomically precise defects.

Triangulene and its π-extended homologues constitute non-Kekulé polyradical frameworks with high-spin ground states, and are anticipated to be key components of organic spintronic devices. We report a combined in-solution and on-surface synthesis of the hitherto largest triangulene homologue, [7]triangulene (C78H24), consisting of twenty-eight benzenoid rings fused in a triangular fashion. We employ low-temperature scanning tunneling microscopy to confirm the chemical structure of individual molecules adsorbed on a Cu(111) surface. While neutral [7]triangulene in the gas phase is predicted to have an open-shell septet ground state; our scanning tunneling spectroscopy measurements, in combination with density functional theory calculations, reveal chemisorption of [7]triangulene on Cu(111) together with considerable charge transfer, resulting in a closed-shell state. Furthermore, substantial hybridization between the molecular orbitals of [7]triangulene is observed.

Polymer semiconductors (PSCs) are an essential component of organic field-effect transistors (OFETs), but their potential for stretchable electronics is limited by their brittleness and failure susceptibility upon strain. Herein, a covalent connection of two state-of-the-art polymers-semiconducting poly-diketo-pyrrolopyrrole-thienothiophene (PDPP-TT) and elastomeric poly(dimethylsiloxane) (PDMS)-in a single triblock copolymer (TBC) chain is reported, which enables high charge carrier mobility and low modulus in one system. Three TBCs containing up to 65 wt% PDMS were obtained, and the TBC with 65 wt% PDMS content exhibits mobilities up to 0.1 cm 2  V -1  s -1 , in the range of the fully conjugated reference polymer PDPP-TT (0.7 cm 2  V -1  s -1 ). The TBC is ultrasoft with a low elastic modulus (5 MPa) in the range of mammalian tissue. The TBC exhibits an excellent stretchability and extraordinary durability, fully maintaining the initial electric conductivity in a doped state after 1500 cycles to 50% strain., (© 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Structurally well-defined graphene nanoribbons (GNRs) have emerged as highly promising materials for the next-generation nanoelectronics. The electronic properties of GNRs critically depend on their edge topologies. Here, we demonstrate the efficient synthesis of a curved GNR ( cGNR ) with a combined cove, zigzag, and armchair edge structure, through bottom-up synthesis. The curvature of the cGNR is elucidated by the corresponding model compounds tetrabenzo[ a,cd,j,lm ]perylene ( 1 ) and diphenanthrene-fused tetrabenzo[ a,cd,j,lm ]perylene ( 2 ), the structures of which are unambiguously confirmed by the X-ray single-crystal analysis. The resultant multi-edged cGNR exhibits a well-resolved absorption at the near-infrared (NIR) region with a maximum peak at 850 nm, corresponding to a narrow optical energy gap of ∼1.22 eV. Employing THz spectroscopy, we disclose a long scattering time of ∼60 fs, corresponding to a record intrinsic charge carrier mobility of ∼600 cm 2 V -1 s -1 for photogenerated charge carriers in cGNR .

Stiff thermosensitive hydrogels (HG) were synthesized by self-crosslinking free radical polymerization of N,N -dimethylacrylamide (DMAA) and N-isopropylacrylamide (NIPAAm), adjusting the degree of swelling by carboxylate-containing sodium acrylate (NaAc) or a 2-oxazoline macromonomer (MM). The formation of hydrogels was possible due to the self-crosslinking property of DMAA when polymerized with peroxodisulfate initiator type. The MM was synthetized by the ring-opening cationic polymerization of 2-methyl-2-oxazoline (MeOxa) and methyl-3-(oxazol-2-yl)-propionate (EsterOxa), and contained a polymerizable styryl endgroup. After ester hydrolysis of EsterOxa units, a carboxylate-containing MM was obtained. The structure of the hydrogels was confirmed by 1 H high-resolution (HR)-MAS NMR spectroscopy. Suitable conditions and compositions of the comonomers have been found, which allowed efficient self-crosslinking as well as a thermoresponsive swelling in water. Incorporation of both the polar comonomer and the macromonomer, in small amounts furthermore allowed the adjustment of the degree of swelling. However, the macromonomer was better suited to retain the thermoresponsive behavior of the poly (NIPAAm) due to a phase separation of the tangling polyoxazoline side chains. Thermogravimetric analysis determined that the hydrogels were stable up to ~ 350 °C, and dynamic mechanical analysis characterized a viscoelastic behavior of the hydrogels, properties that are required, for example, for possible use as an actuator material.

Nanographenes (NGs) with tunable electronic and magnetic properties have attracted enormous attention in the realm of carbon-based nanoelectronics. In particular, NGs with biradical character at the ground state are promising building units for molecular spintronics. However, most of the biradicaloids are susceptible to oxidation under ambient conditions and photolytic degradation, which hamper their further applications. Herein, we demonstrated the feasibility of tuning the magnetic properties of zigzag-edged NGs in order to enhance their stability via the controlled Diels-Alder reactions of peri-tetracene (4-PA). The unstable 4-PA (y 0 =0.72; half-life, t 1/2 =3 h) was transformed into the unprecedented benzo-peri-tetracenes (BPTs) by a one-side Diels-Alder reaction, which featured a biradical character at the ground state (y 0 =0.60) and exhibited remarkable stability under ambient conditions for several months. In addition, the fully zigzag-edged circumanthracenes (CAs) were achieved by two-fold or stepwise Diels-Alder reactions of 4-PA, in which the magnetic properties could be controlled by employing the corresponding dienophiles. Our work reported herein opens avenues for the synthesis of novel zigzag-edged NGs with tailor-made magnetic properties., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Three unprecedented helical nanographenes (1, 2, and 3) containing an azulene unit are synthesized. The resultant helical structures are unambiguously confirmed by X-ray crystallographic analysis. The embedded azulene unit in 2 possesses a record-high twisting degree (16.1°) as a result of the contiguous steric repulsion at the helical inner rim. Structural analysis in combination with theoretical calculations reveals that these helical nanographenes manifest a global aromatic structure, while the inner azulene unit exhibits weak antiaromatic character. Furthermore, UV/Vis-spectral measurements reveal that superhelicenes 2 and 3 possess narrow energy gaps (2: 1.88 eV; 3: 2.03 eV), as corroborated by cyclic voltammetry and supported by density functional theory (DFT) calculations. The stable oxidized and reduced states of 2 and 3 are characterized by in-situ EPR/Vis-NIR spectroelectrochemistry. Our study provides a novel synthetic strategy for helical nanographenes containing azulene units as well as their associated structures and physical properties., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

In order to evaluate the potential of a technology platform based on hyaluronan copolymers grafted with propargylated ferulate fluorophores (HA-FA-Pg) in the development of drug delivery systems, the propargyl groups of HA-FA-Pg derivatives were employed with oleic acid (OA) or stearic acid (SA) residues across a biocompatible hexa(ethylene glycol) (HEG) spacer. The designed materials (i.e., HA-FA-HEG-OA or HA-FA-HEG-SA ) showed clear-cut aggregation features in an aqueous environment, as confirmed by dynamic light scattering (DLS) and transmission electron microscopy (TEM), generating nanoaggregate systems. In fact, HA-FA-HEG-OA and HA-FA-HEG-SA derivatives showed the property to create self-assembled cytocompatible nanostructured aggregates in water, thanks to the simultaneous presence of hydrophilic portions in the polymeric backbone, such as hyaluronic acid, and hydrophobic portions in the side chains. Furthermore, the designed materials interact with living cells showing a high degree of cytocompatibility. The potential ability of nanosystems to load pharmacologically active molecules was assessed by the physical entrapment of olanzapine into both polymeric systems. The drug loading evaluation demonstrated that the nanoparticles are able to incorporate a good quantity of olanzapine, as well as improve drug solubility, release profile, and cytocompatibility.

Nonbenzenoid carbocyclic rings are postulated to serve as important structural elements toward tuning the chemical and electronic properties of extended polycyclic aromatic hydrocarbons (PAHs, or namely nanographenes), necessitating a rational and atomically precise synthetic approach toward their fabrication. Here, using a combined bottom-up in-solution and on-surface synthetic approach, we report the synthesis of nonbenzenoid open-shell nanographenes containing two pairs of embedded pentagonal and heptagonal rings. Extensive characterization of the resultant nanographene in solution shows a low optical gap, and an open-shell singlet ground state with a low singlet-triplet gap. Employing ultra-high-resolution scanning tunneling microscopy and spectroscopy, we conduct atomic-scale structural and electronic studies on a cyclopenta-fused derivative on a Au(111) surface. The resultant five to seven rings embedded nanographene displays an extremely narrow energy gap of 0.27 eV and exhibits a pronounced open-shell biradical character close to 1 ( y 0 = 0.92). Our experimental results are supported by mean-field and multiconfigurational quantum chemical calculations. Access to large nanographenes with a combination of nonbenzenoid topologies and open-shell character should have wide implications in harnessing new functionalities toward the realization of future organic electronic and spintronic devices.

On-surface synthesis provides an effective approach toward the formation of graphene nanostructures that are difficult to achieve via traditional solution chemistry. Here, we report on the design and synthesis of a nonplanar porous nanographene with 78 sp 2 carbon atoms, namely C78. Through a highly selective oxidative cyclodehydrogenation of 2,3,6,7,10,11-hexa(naphthalen-1-yl)triphenylene (2), propeller nanographene precursor 1 was synthesized in solution. Interestingly, although 1 could not be cyclized further in solution, porous nanographene C78 was successfully achieved from 1 by on-surface assisted cyclodehydrogenation on Au(111). The structure and electronic properties of C78 have been investigated by means of scanning tunneling microscopy, noncontact atomic force microscopy, and scanning tunneling spectroscopy, complemented by computational investigations. Our results provide perspectives for the on-surface synthesis of porous graphene nanostructures, offering a promising strategy for the engineering of graphene materials with tailor-made properties.

Controlling the aromaticity and electronic properties of curved π-conjugated systems has been increasingly attractive for the development of novel functional materials for organic electronics. Herein, we demonstrate an efficient synthesis of two novel wave-shaped polycyclic hydrocarbons (PHs) 1 and 2 with 64 π-electrons. Among them, the wave-shaped π-conjugated carbon skeleton of 2 is unambiguously revealed by single-crystal X-ray crystallography analysis. The wave-shaped geometry is induced by steric congestion in the cove and fjord regions. Remarkably, the aromaticity of these two structural isomers can be tailored by the annulated direction of cyclopenta[ b ]fluorene units. Isomer 1 ( E optg = 1.13 eV) behaves as a closed-shell compound with weakly antiaromatic feature, whereas its structural isomer 2 displays a highly stable tetraradical character ( y 0 = 0.23; y 1 = 0.22; t 1/2 = 91 days) with a narrow optical energy gap of 0.96 eV. Moreover, the curved PH 2 exhibits remarkable ambipolar charge transport in solution-processed organic thin-film transistors. Our research provides a new insight into the design and synthesis of stable functional curved aromatics with multiradical characters.

Junction-functionalized donor-acceptor (D-A) block copolymers (BCPs) enable spatial and electronic control over interfacial charge dynamics in excitonic devices such as solar cells. Here, we present the design, synthesis, morphology, and electronic characterization of block junction-functionalized, all-conjugated, all-crystalline D-A BCPs. Poly(3-hexylthiophene) (P3HT), a single thienylated diketopyrrolopyrrole (Th x DPPTh x , x = 1 or 2) unit, and poly{[ N, N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]- alt-5,5'-(2,2'-bithiophene)} (PNDIT2) are used as donor, interfacial unit, and acceptor, respectively. Almost all C-C coupling steps are accomplished by virtue of C-H activation. Synthesis of the macroreagent H-P3HT-Th x DPPTh x , with x determining its C-H reactivity, is key to the synthesis of various BCPs of type H-P3HT-Th x DPPTh x - block-PNDIT2. Morphology is determined from a combination of calorimetry, transmission electron microscopy (TEM), and thin-film scattering. Block copolymer crystallinity of P3HT and PNDIT2 is reduced, indicating frustrated crystallization. A long period l p is invisible from TEM, but shows up in resonant soft X-ray scattering experiments at a length scale of l p ∼ 60 nm. Photoluminescence of H-P3HT-Th x DPPTh x indicates efficient transfer of the excitation energy to the DPP chain end, but is quenched in BCP films. Transient absorption and pump-push photocurrent spectroscopies reveal geminate recombination (GR) as the main loss channel in as-prepared BCP films independent of junction functionalization. Melt annealing increases GR as a result of the low degree of crystallinity and poorly defined interfaces and additionally changes backbone orientation of PNDIT2 from face-on to edge-on. These morphological effects dominate solar cell performance and cause an insensitivity to the presence of the block junction.

Zigzag-edged nanographene with two rows of fused linear acenes, called as n- peri-acene (n-PA), is considered as a potential building unit in the arena of organic electronics. n-PAs with four ( peri-tetracene, 4-PA), five ( peri-pentacene, 5-PA) or more benzene rings in a row have been predicted to show open-shell character, which would be attractive for the development of unprecedented molecular spintronics. However, solution-based synthesis of open-shell n-PA has thus far not been successful because of the poor chemical stability. Herein we demonstrated the synthesis and characterization of the hitherto unknown 4-PA by a rational strategy in which steric protection of the zigzag edges playing a pivotal role. The obtained 4-PA possesses a singlet biradical character ( y 0 = 72%) and exhibits remarkable persistent stability with a half-life time ( t 1/2 ) of ∼3 h under ambient conditions. UV-vis-NIR and electrochemical measurements reveal a narrow optical/electrochemical energy gap (1.11 eV) for 4-PA. Moreover, the bay regions of 4-PA enable the efficient 2-fold Diels-Alder reaction, yielding a novel full zigzag-edged circumanthracene.

A hydroxyl group containing new cardo diamine monomer was synthesized, namely 9,9-bis (hydroxy- (4'-amino(3-trifluoromethyl)biphenyl-4-oxy)-phenyl)-9H-fluorene (mixture of isomers, HAPHPF). HAPHPF, along with a sulfonated diamine monomer, 4,4'-diaminostilbene-2,2'-disulfonic acid (DSDSA), was used to prepare a series of new sulfonated copolyimides by polycondensation with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). The degree of sulfonation (DS < 1) was adjusted by the feed ratio of DSDSA/HAPHPF and the copolymers were named as DHN-XX, where XX denotes the mole percentage of DSDSA (XX = 50, 60, and 70). The copolymers showed high molecular weights. The copolymer structure and composition were confirmed by FTIR and NMR techniques. Copolymer membranes were prepared through solution cast route by using dimethyl sulfoxide as a solvent. The membranes showed high thermal, mechanical, hydrolytic and peroxide radical stability, and low water uptake and low swelling ratios. Well-separated hydrophilic and hydrophobic phase morphology was observed in TEM and AFM images of the copolymer membranes and was further supported by the SAXS studies. The proton conductivity of the DHN-70 was as high as 97 mS cm -1 at 80 °C and the value is significantly higher than that of the nonhydroxylated analogue. The membranes also showed superior microbial fuel cell (MFC) performance, similar like Nafion 117 under similar test conditions. The chemical oxygen demand removal values provide substantial evidence that the fabricated membranes can be utilized in bioelectrochemical systems.

The synthesis, characterization, and charge transport performance of novel copolymers PNDIFu2 made from alternating naphthalene diimide (NDI) and bifuran (Fu2) units are reported. Usage of potentially biomass-derived Fu2 as alternating repeat unit enables flattened polymer backbones due to reduced steric interactions between the imide oxygens and Fu2 units, as seen by density functional theory (DFT) calculations and UV-vis spectroscopy. Aggregation of PNDIFu2 in solution is enhanced if compared to the analogous NDI-bithiophene (T2) copolymers PNDIT2, occurring in all solvents and temperatures probed. PNDIFu2 features a smaller π-π stacking distance of 0.35 nm compared to 0.39 nm seen for PNDIT2. Alignment of aggregates in films is achieved by using off-center spin coating, whereby PNDIFu2 exhibits a stronger dichroic ratio and transport anisotropy in field-effect transistors (FET) compared to PNDIT2, with an overall good electron mobility of 0.21 cm 2 /(V s). Despite an enhanced backbone planarity, the smaller π-π stacking and the enhanced charge transport anisotropy, the electron mobility of PNDIFu2 is about three times lower compared to PNDIT2. Density functional theory calculations suggest that charge transport in PNDIFu2 is limited by enhanced polaron localization compared to PNDIT2.

Synthesis of antiaromatic polycyclic hydrocarbons (PHs) is challenging because the high energy of their highest occupied molecular orbital and low energy of their lowest unoccupied molecular orbital cause them to be reactive and unstable. In this work, two large antiaromatic acene analogues, namely, cyclopenta[pqr]indeno[2,1,7-ijk]tetraphene (CIT, 1a) and cyclopenta[pqr]indeno[7,1,2-cde]picene (CIP, 1b), as well as a curved antiaromatic molecule with 48 π-electrons, dibenzo[a,c]diindeno[7,1,2-fgh:7',1',2'-mno]phenanthro[9,10-k]tetraphene (DPT, 1c), are synthesized on the basis of the corona of indeno[1,2-b]fluorene. These three antiaromatic PHs possess a narrow energy gap down to 1.55 eV and exhibit high kinetic stability under ambient conditions. Moreover, these compounds display reversible electron transfer processes in both the cathodic and anodic regimes. Their cation and anion radicals are characterized by in situ vis-NIR absorption and electron paramagnetic resonance spectroelectrochemistry. The X-ray crystallographic analysis confirms that while CIP and CIT manifest planar structures, DPT shows a curved π-conjugated carbon skeleton. The synthetic strategy starting from ortho-substituted benzene units to construct five-membered rings in this work provides a unique entry to novel pentagon-embedding or curved antiaromatic polycyclic hydrocarbons. In addition, besides the detailed chemical and physical investigations, microscale single-crystal fiber field-effect transistors were also fabricated.

Diindeno-fused bischrysene, a new diindeno-based polycyclic hydrocarbon (PH), was synthesized and characterized. It was elucidated in detailed experimental and theoretical studies that this cyclopenta-fused PH possesses an open-shell singlet biradical structure in the ground state and exhibits high stability under ambient conditions (t 1/2 =39 days). The crystal structure unambiguously shows a novel saddle-shaped π-conjugated carbon skeleton due to the steric hindrance of the central cove-edged bischrysene unit. UV/Vis spectral measurements revealed that the title molecule has a very narrow optical energy gap of 0.92 eV, which is consistent with the electrochemical analysis and further supported by density functional theory (DFT) calculations., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Key parameters allow a reproducible polyassociation between avidin and biotinylated glycopolymers in order to fabricate defined supramolecular nanostructures for future (bio)medical and biotechnological applications. Thus, the polymerization efficiency of biotinylated glycopolymers in the fabrication of biohybrid structures (BHS) was investigated with regard to the influence of (i) the degree of biotinylation of the dendritic glycoarchitectures, (ii) two biotin linkers, (iii) the dendritic scaffold (perfectly branched vs hyperbranched), and (iv) the ligand-receptor stoichiometry. The adjustment of all these parameters opens the way to fabricate defined sizes of the final biohybrid structures as a multifunctional platform ready for their use in different applications. Various analytical techniques, including purification of BHS, were used to gain fundamental insights into the structural properties of the resulting protein-glycopolymer BHS. Finally, the elucidation of pivotal conformational properties of isolated BHS with defined sizes by asymmetrical flow field flow fractionation study revealed that they mainly possess spherical-/star-like properties. From this study, the fundamental knowledge can be likely transferred to other assemblies formed by molecular recognition processes (e.g., adamantane-β-cyclodextrin).

The solvent for direct arylation polycondensation (DAP) is of crucial importance. For conjugated polymers exhibiting reduced solubility, the choice of solvent decides on the maximum molecular weight that can be achieved, hence, good aromatic solvents are generally desirable. However, unintentional activation of C-H bonds present in aromatic solvents under DAP conditions leads to in situ solvent termination which competes with step growth. Here we evaluate relative C-H reactivity and solvent quality of seven aromatic solvents for the DAP of defect-free naphthalene diimide (NDI)-based copolymers of different solubility. C-H reactivity is strongly reduced with increasing degree of substitution for both chlorine and methyl substituents. Mesitylene is largely C-H unreactive and, thus, albeit being a moderate solvent, enables very high molecular weights at elevated temperature for NDI copolymers with limited solubility.

A highly efficient, simple, and environmentally friendly protocol for the synthesis of an alternating naphthalene diimide bithiophene copolymer (PNDIT2) via direct arylation polycondensation (DAP) is presented. High molecular weight (MW) PNDIT2 can be obtained in quantitative yield using aromatic solvents. Most critical is the suppression of two major termination reactions of NDIBr end groups: nucleophilic substitution and solvent end-capping by aromatic solvents via C-H activation. In situ solvent end-capping can be used to control MW by varying monomer concentration, whereby end-capping is efficient and MW is low for low concentration and vice versa. Reducing C-H reactivity of the solvent at optimized conditions further increases MW. Chain perfection of PNDIT2 is demonstrated in detail by NMR spectroscopy, which reveals PNDIT2 chains to be fully linear and alternating. This is further confirmed by investigating the optical and thermal properties as a function of MW, which saturate at Mn ≈ 20 kDa, in agreement with controls made by Stille coupling. Field-effect transistor (FET) electron mobilities μsat up to 3 cm(2)/(V·s) are measured using off-center spin-coating, with FET devices made from DAP PNDIT2 exhibiting better reproducibility compared to Stille controls.

Pd-catalyzed direct arylation (DA) reaction conditions have been established for unsubstituted furan (Fu) and thiophene (Th) with three popular acceptor building blocks to be used in materials for organic electronics, namely 4,7-dibromo-2,1,3-benzothiadiazole (BTBr2), N,N′-dialkylated 2,6-dibromonaphthalene-1,4,5,8-bis(dicarboximide) (NDIBr2), and 1,4-dibromotetrafluorobenzene (F4Br2). Reactions with BTBr2, F4Br2, and NDIBr2 require different solvents to obtain high yields. The use of dimethylacetamide (DMAc) is essential for the successful coupling of BTBr2 and F4Br2, but detrimental for NDIBr2, as the electron-deficient NDI core is prone to nucleophilic core substitution in DMAc as solvent but not in toluene. NDIFu2 is much more planar compared to NDITh2, resulting in an enhanced charge-transfer character, which makes it an interesting building block for conjugated systems designed for organic electronics. This study highlights direct arylation as a simple and inexpensive method to construct a series of important donor–acceptor–donor building blocks to be further used for the preparation of a variety of conjugated materials.

Direct arylation (DA) of 2-chlorothiophene and 2-chloro-3-hexylthiophene with 4,7-dibromo-2,1,3-benzothiadiazole is used to synthesize 4,7-bis(5-chloro-2-thienyl)-2,1,3-benzothiadiazole (TBTCl2) and 4,7-bis(5-chloro-4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (DH-TBTCl2) in one step. Suitable conditions of the Suzuki polycondensations (SPC) of TBTCl2 and DH-TBTCl2 with the carbazole comonomer CbzPBE2 are established, furnishing PCDTBT and P(Cbz-alt-TBT) with high molecular weight and yield. Compared with control samples made from the corresponding dibromides, high-temperature NMR and UV-vis spectroscopy indicate similar properties for PCDTBT but an increased content of Cbz-Cbz homocouplings for P(Cbz-alt-TBT)., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Specific noncovalent interactions are commonly used by nature to modulate numerous processes including cell recognition, viral adhesion, and transmembrane communications. Here we report on the design, synthesis, and preliminary characterization of new supramolecular glycodendrimer-based hybrid drugs based on adamantyl-modified glycodendrimers of third, fourth, or fifth generation (mPPI-G3-AdaB, mPPI-G4-AdaB, and mPPI-G5-AdaB) and a new heterobifunctional ligand. This component was tailored to bind through noncovalent interactions both the multimeric natural 5-HT3 receptor (through an optimized arylpiperazine pharmacophore) and the adamantyl groups located on the glycodendrimer surfaces (through a β-cyclodextrin residue) giving rise to biorelevant supramolecular constructs.