136 results found
Laidlaw B, Eng J, Wade J, et al., 2021, On the factors influencing the chiroptical response of conjugated polymer thin films., Chem Commun (Camb)
We study the influence of the physical and chemical structure on the chiroptical response of fluorene-based polymeric systems, namely poly(9,9-dioctylfluorene) (PFO) and the donor-acceptor type copolymer poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT). We reveal the significance of electric-magnetic coupling, at both short (molecular-level) and intermediate (delocalised over multiple polymer chains) length scales, on the magnitude of the dissymmetry. These findings provide a framework for the design of new materials with an enhanced chiroptical response.
Greenfield J, Mihael G, Gibson R, et al., 2021, Efficient electrocatalytic switching of azoheteroarenes in the condensed phases, Journal of the American Chemical Society, ISSN: 0002-7863
Azo-based photoswitches have shown promise as molecular solar thermal (MOST) materials, due to their ability to storeenergy in their metastable Z isomeric form. The energy is then released, in the form of heat, upon photoisomerisation to thethermodynamically stable E form. However, obtaining a high energy density and recovering the stored energy with high efficiency requiresthe materials to be employed in the condensed phase and display a high degree of Z to E switching, respectively: both of which arechallenging to engineer. Here we show that arylazopyrazole motifs undergo efficient redox-induced Z to E switching in both the solutionand condensed phase, to a higher completeness of switching than achieved photochemically. This redox-initiated pathway lowers thebarrier to Z to E isomerization by 27 kJ/mol, whilst in the condensed phase, the efficiency of electrochemical switching is improved by overan order of magnitude relative to that in the solution state. The influence of the photoswitch’s phase, electrical conductivity, and viscosityon the electrochemical switching in the condensed phase is reported, culminating in a set of design rules to facilitate further investigations.We anticipate the use of an alternative stimulus to light will facilitate the application of MOST materials in situations where photo-triggeredheat release is unachievable or inefficient, e.g. indoor or at night. Furthermore, exploiting the electrocatalytic mechanism, whereby acatalytic amount of charge triggers Z to E switching via a redox process, bypasses the need for fine-tuning of the photoswitchingchromophore to achieve complete Z to E switching, thus providing an alternative approach to photoswitch molecular design.
Schmidt J, Weatherby J, Sugden I, et al., 2021, Computational screening of organic semiconductors: exploring side-group functionalisation and assembly to optimise charge transport in chiral molecules, Crystal Growth and Design, ISSN: 1528-7483
Molecular materials are challenging to design as their packing arrangement and hence properties are subject to subtle variations in the interplay of soft intermolecular interactions that are difficult to predict. The rational design of new molecular materials with tailored properties is currently hampered by the lack of knowledge of how a candidate molecule will pack in space and how we can control the polymorphs we can experimentally obtain. Here, we develop a simplified approach to aid the material design process, by the development of a screening process that is used to test 1344 helicene molecules that have potential as organic electronic materials. Our approach bridges the gap between single molecule design, molecular assembly, and the resulting charge-carrier mobilities. We find that fluorination significantly improves electron transport in the molecular material by up to 200%; the reference helicene packing showed a mobility of 0.30 cm2 V-1 s-1, fluorination increased the mobility to up to 0.96 and 0.97 (13-fluoroH and 4,13-difluoroH), assuming an outer reorganisation energy of 0.30 eV. Side groups containing triple bonds largely lead to improved transfer integrals. We validate our screening approach through the use of crystal structure prediction to confirm the presence of favourable packing motifs to maximize charge mobility.
Wan L, Shi X, Wade J, et al., 2021, Strongly Circularly Polarized Crystalline and beta-Phase Emission from Poly(9,9-dioctylfluorene)-Based Deep-Blue Light-Emitting Diodes, ADVANCED OPTICAL MATERIALS, ISSN: 2195-1071
LanyonHogg T, Ritzefeld M, Zhang L, et al., 2021, Photochemical Probe Identification of a Small‐Molecule Inhibitor Binding Site in Hedgehog Acyltransferase (HHAT)**, Angewandte Chemie, Vol: 133, Pages: 13654-13659, ISSN: 0044-8249
Lanyon-Hogg T, Ritzefeld M, Zhang L, et al., 2021, Photochemical probe identification of the small-molecule binding site in a mammalian membrane-bound O-acyltransferase, Angewandte Chemie International Edition, Vol: 60, Pages: 13542-13547, ISSN: 1433-7851
The mammalian membrane‐bound O ‐acyltransferase (MBOAT) superfamily is involved in biological processes including growth, development and appetite sensing. MBOATs are attractive drug targets in cancer and obesity; however, information on the binding site and molecular mechanisms underlying small‐molecule inhibition is elusive. This study reports rational development of a photochemical probe to interrogate a novel small‐molecule inhibitor binding site in the human MBOAT Hedgehog acyltransferase (HHAT). Structure‐activity relationship investigation identified single enantiomer IMP‐1575 , the most potent HHAT inhibitor reported to‐date, and guided design of photocrosslinking probes that maintained HHAT‐inhibitory potency. Photocrosslinking and proteomic sequencing of HHAT delivered identification of the first small‐molecule binding site in a mammalian MBOAT. Topology and homology data suggested a potential mechanism for HHAT inhibition which was confirmed via kinetic analysis. Our results provide an optimal HHAT tool inhibitor IMP‐1575 ( K i = 38 nM) and a strategy for mapping small molecule interaction sites in MBOATs.
Greenfield JL, Wade J, Brandt JR, et al., 2021, Pathways to increase the dissymmetry in the interaction of chiral light and chiral molecules, CHEMICAL SCIENCE, ISSN: 2041-6520
Wade J, Higgins SG, Heutz S, et al., 2021, In memoriam Alasdair James Campbell (11 May 1961-27 February 2021), Journal of Materials Chemistry C, Vol: 9, Pages: 6100-6102, ISSN: 2050-7526
Ward M, Wade J, Shi X, et al., 2021, Highly Selective Ultrafast Circularly Polarized Photodiodes Based on π-Conjugated Polymers
<jats:p>Chiral π-conjugated molecular systems that are intrinsically sensitive to the handedness of circularly polarized (CP) light potentially allow for miniaturized, low-cost CP detection devices. Such devices promise to transform several technologies, including biosensing, quantum optics and communication of data encrypted by exploiting the spin angular momentum of light. Here we realize a simple, bilayer organic photodiode (CP OPD) comprising an achiral π-conjugated polymer–chiral additive blend as the electron donor layer and an achiral C<sub>60</sub> electron acceptor layer. These devices exhibit considerable photocurrent dissymmetry <i>g</i><sub>ph</sub>, with absolute values as high as 0.85 and dark currents as low as 10 pA. Impressively, they showcase a linear dynamic range of 80 dB, and rise and fall times of 50 and 270 ns respectively, which significantly outperforms all previously reported CP selective photodetectors. Mechanistically, we show that the <i>g</i><sub>ph</sub> is sensitive to the thickness of <i>both</i> the chiral donor and achiral acceptor layers and that a trade-off exists between the external quantum efficiency (EQE) and <i>g</i><sub>ph</sub>. The fast-switching speeds of these devices, coupled with their large dynamic range and highly selective response to CP light, opens up the possibility of their direct application in CP sensing and optical communication.</jats:p>
Miguel-Blanco C, Murithi JM, Benavente ED, et al., 2021, The antimalarial efficacy and mechanism of resistance of the novel chemotype DDD01034957, Scientific Reports, Vol: 11, ISSN: 2045-2322
New antimalarial therapeutics are needed to ensure that malaria cases continue to be driven down, as both emerging parasite resistance to frontline chemotherapies and mosquito resistance to current insecticides threaten control programmes. Plasmodium, the apicomplexan parasite responsible for malaria, causes disease pathology through repeated cycles of invasion and replication within host erythrocytes (the asexual cycle). Antimalarial drugs primarily target this cycle, seeking to reduce parasite burden within the host as fast as possible and to supress recrudescence for as long as possible. Intense phenotypic drug screening efforts have identified a number of promising new antimalarial molecules. Particularly important is the identification of compounds with new modes of action within the parasite to combat existing drug resistance and suitable for formulation of efficacious combination therapies. Here we detail the antimalarial properties of DDD01034957-a novel antimalarial molecule which is fast-acting and potent against drug resistant strains in vitro, shows activity in vivo, and possesses a resistance mechanism linked to the membrane transporter PfABCI3. These data support further medicinal chemistry lead-optimization of DDD01034957 as a novel antimalarial chemical class and provide new insights to further reduce in vivo metabolic clearance.
Shi W, Salerno F, Ward MD, et al., 2021, Fullerene desymmetrization as a means to achieve single-enantiomer electron acceptors with maximized chiroptical responsiveness., Advanced Materials, Vol: 33, Pages: 1-7, ISSN: 0935-9648
Solubilized fullerene derivatives have revolutionized the development of organic photovoltaic devices, acting as excellent electron acceptors. The addition of solubilizing addends to the fullerene cage results in a large number of isomers, which are generally employed as isomeric mixtures. Moreover, a significant number of these isomers are chiral, which further adds to the isomeric complexity. The opportunities presented by single-isomer, and particularly single-enantiomer, fullerenes in organic electronic materials and devices are poorly understood however. Here, ten pairs of enantiomers are separated from the 19 structural isomers of bisphenyl-C61-butyric acid methyl ester, using them to elucidate important chiroptical relationships and demonstrating their application to a circularly polarized light (CPL)-detecting device. Larger chiroptical responses are found, occurring through the inherent chirality of the fullerene. When used in a single-enantiomer organic field-effect transistor, the potential to discriminate CPL with a fast light response time and with a very high photocurrent dissymmetry factor (gph = 1.27 ± 0.06) is demonstrated. This study thus provides key strategies to design fullerenes with large chiroptical responses for use as chiral components of organic electronic devices. It is anticipated that this data will position chiral fullerenes as an exciting material class for the growing field of chiral electronic technologies.
Wade J, Brandt JR, Reger D, et al., 2021, 500‐Fold Amplification of Small Molecule Circularly Polarised Luminescence through Circularly Polarised FRET, Angewandte Chemie, Vol: 133, Pages: 224-229, ISSN: 0044-8249
Wade J, Hilfiker J, Brandt J, et al., 2020, Natural optical activity as the origin of the large chiroptical properties in π-conjugated polymer thin films, Nature Communications, Vol: 11, Pages: 1-11, ISSN: 2041-1723
Polymer thin films that emit and absorb circularly polarised light have been demonstrated with the promise of achieving important technological advances; from efficient, high-performance displays, to 3D imaging and all-organic spintronic devices. However, the origin of the large chiroptical effects in such films has, until now, remained elusive. We investigate the emergence of such phenomena in achiral polymers blended with a chiral small-molecule additive (1-azahelicene) and intrinsically chiral-sidechain polymers using a combination of spectroscopic methods and structural probes. We show that – under conditions relevant for device fabrication – the large chiroptical effects are caused by magneto-electric coupling (natural optical activity), not structural chirality as previously assumed, and may occur because of local order in a cylinder blue phase-type organisation. This disruptive mechanistic insight into chiral polymer thin films will offer new approaches towards chiroptical materials development after almost three decades of research in this area.
Fuchter MJ, 2020, On the promise of photopharmacology using photoswitches: a medicinal chemist's perspective., Journal of Medicinal Chemistry, Vol: 63, Pages: 11436-11447, ISSN: 0022-2623
Photopharmacology is a growing area of endeavor that employs photoswitchable ligands to allow for light-dependent pharmacological activity. By coupling light to therapeutic action, improved spatial and temporal selectivity can be achieved and subsequently harnessed for new concepts in therapy. Tremendous progress has already been made, with photopharmacological agents now reported against a wide array of target classes, and light-dependent results demonstrated in a range of live cell and animal models. Several challenges remain however, especially in order for photopharmacology to truly impact the clinical management of disease. This perspective aims to summarize these challenges, particularly with attention to the medicinal chemistry that will be unavoidably required for the further translation of these agents/approaches. By clearly defining challenges for drug hunters, it is hoped that further research into the medicinal chemistry of photopharmacological agents will be stimulated; ultimately enabling full realization of the huge potential for this exciting field.
Lam P-Y, Thawani AR, Balderas E, et al., 2020, TRPswitch — a step function chemo-optogenetic ligand for the vertebrate TRPA1 channel, Journal of the American Chemical Society, Vol: 142, Pages: 17457-17468, ISSN: 0002-7863
Chemo-optogenetics has produced powerful tools for optical control of cell activity, but current tools suffer from a variety of limitations including low unitary conductance, the need to modify the target channel, or the inability to control both on and off switching. Using a zebrafish behavior-based screening strategy, we discovered “TRPswitch”, a photoswitchable non-electrophilic ligand scaffold for the transient receptor potential ankyrin 1 (TRPA1) channel. TRPA1 exhibits high unitary channel conductance, making it an ideal target for chemo-optogenetic tool development. Key molecular determinants for the activity of TRPswitch were elucidated and allowed for replacement of the TRPswitch azobenzene with a next-generation azoheteroarene. The TRPswitch compounds enable reversible, repeatable, and nearly quantitative light-induced activation and deactivation of the vertebrate TRPA1 channel with violet and green light, respectively. The utility of TRPswitch compounds was demonstrated in larval zebrafish hearts exogenously expressing zebrafish Trpa1b, where heartbeat could be controlled using TRPswitch and light. Therefore, TRPA1/TRPswitch represents a novel step-function chemo-optogenetic system with a unique combination of high conductance, high efficiency, activity against an unmodified vertebrate channel, and capacity for bidirectional optical switching. This chemo-optogenetic system will be particularly applicable in systems where a large depolarization current is needed or sustained channel activation is desirable.
Wade J, Brandt J, Reger D, et al., 2020, 500‐fold amplification of small molecule circularly polarized luminescence through circularly polarized FRET, Angewandte Chemie International Edition, ISSN: 1433-7851
Strongly dissymmetric circularly polarised (CP) luminescence from small organic molecules could transform a range of technologies, such as display devices. However, highly dissymmetric emission is usually not possible with small organic molecules, which typically give dissymmetric factors of photoluminescence ( g PL ) less than 10 ‐2 . Here we describe an almost 10 3 ‐fold chiroptical amplification of a π‐extended superhelicene when embedded in an achiral conjugated polymer matrix. This combination increases the |gPL| of the superhelicene from approximately 3 × 10 ‐4 in solution to 0.15 in a blend film in the solid‐state. We propose that the amplification arises not simply through a chiral environment effect, but instead due to electrodynamic coupling between the electric and magnetic transition dipoles of the polymer donor and superhelicene acceptor, and subsequent CP Förster resonance energy transfer. We show that this amplification effect holds across several achiral polymer hosts and thus represents a simple and versatile approach to enhance the g‐factors of small organic molecules.
Wan L, Wade J, Shi X, et al., 2020, Highly Efficient Inverted Circularly Polarized Organic Light-Emitting Diodes, ACS Applied Materials & Interfaces, Vol: 12, Pages: 39471-39478, ISSN: 1944-8244
Circularly polarized (CP) electroluminescence has been demonstrated as a strategy to improve the performance of organic light-emitting diode (OLED) displays. CP emission can be generated from both small-molecule and polymer OLEDs (SM-OLEDs and PLEDs), but to date, these devices suffer from low dissymmetry factors (g-factor < 0.1), poor device performance, or a combination of the two. Here, we demonstrate the first CP-PLED employing an inverted device architecture. Through this approach, we demonstrate a highly efficient CP-PLED, with a current efficiency of 16.4 cd/A, a power efficiency of 16.6 lm/W, a maximum luminance of over 28,500 cd/m2, and a high EL dissymmetry (gEL) of 0.57. We find that the handedness of the emitted light is sensitive to the PLED device architecture: the sign of CP-EL from an identically prepared active layer reverses between inverted and conventional devices. The inverted structure affords the first demonstration of CP-PLEDs exhibiting both high efficiency and high dissymmetry—the two figures of merit which, until now, have been difficult to achieve at the same time. We also highlight device architecture and associated internal electric field to be a previously unexplored means to control the handedness of CP emission. Our findings significantly broaden the versatility of CP emissive devices and should enable their further application in a variety of other CP-dependent technologies.
Uriz-Huarte A, Date A, Ang H, et al., 2020, The transcriptional repressor REV-ERB as a novel target for disease, Bioorganic & Medicinal Chemistry Letters, Vol: 30, Pages: 127395-127395, ISSN: 0960-894X
REV-ERB is a member of the nuclear receptor superfamily of transcription factors involved in the regulation of many physiological processes, from circadian rhythm, to immune function and metabolism. Accordingly, REV-ERB has been considered as a promising, but difficult drug target for the treatment of numerous diseases. Here, we concisely review current understanding of the function of REV-ERB, modulation by endogenous factors and synthetic ligands, and the involvement of REV-ERB in select human diseases. Particular focus is placed on the medicinal chemistry of synthetic REV-ERB ligands, which demonstrates the need for higher quality ligands to aid in robust validation of this exciting target.
Rushworth J, Montgomery K, Cao B, et al., 2020, Glycosylated nanoparticles derived from RAFT polymerization for effective drug delivery to macrophages, ACS Applied Bio Materials, Vol: 3, Pages: 5775-5786, ISSN: 2576-6422
The functional group tolerance and simplicity of reversible addition fragmentation chain transfer (RAFT) polymerization enable its use in the preparation of a wide range of functional polymer architectures for a variety of applications, including drug delivery. Given the role of tumor-associated macrophages (TAMs) in cancer and their dependence on the tyrosine kinase receptor FMS (CSF-1R), the key aim of this work was to achieve effective delivery of an FMS inhibitor to cells using a polymer delivery system. Such a system has the potential to exploit biological features specific to macrophages and therefore provide enhanced selectivity. Building on our prior work, we have prepared RAFT polymers based on a poly(butyl methacrylate-co-methacrylic acid) diblock, which were extended with a hydrophilic block, a cross-linker, and a mannose-based monomer scaffold, exploiting the abundance of macrophage mannose receptors (MMRs, CD206) on the surface of macrophages. We demonstrate that the prepared polymers can be assembled into nanoparticles and are successfully internalized into macrophages, in part, via the MMR (CD206). Finally, we showcase the developed nanoparticles in the delivery of an FMS inhibitor to cells, resulting in inhibition of the FMS receptor. As such, this study lays the groundwork for further drug-delivery studies aimed at specifically targeting TAMs with molecularly targeted therapeutics.
Shi W, Salerno F, Santana-Bonilla A, et al., 2020, Fullerene Dissymmetrization as a Means to Achieve Single Enantiomer Electron Acceptors with Maximized Chiroptical Responsiveness
<jats:p><p>Solubilized fullerene derivatives have revolutionised the development of organic photovoltaic devices, acting as excellent electron acceptors. The addition of solubilizing addends to the fullerene cage results in a large number of isomers, which are generally employed as isomeric mixtures. Moreover, a significant number of these isomers are chiral, which further adds to the isomeric complexity. The opportunities presented by single isomer, and particularly single enantiomer, fullerenes in organic electronic materials and devices are poorly understood. Here we separate 10 pairs of enantiomers from the 19 structural isomers of bisPCBM, using them to elucidate important chiroptical structure-property relationships and demonstrating their application to a single enantiomer circularly polarized (CP) light detecting device. We find that larger chiroptical responses occur through inherent chirality of the fullerene cage and particularly through transitions with low CT character. When used in a single enantiomer organic field-effect transistor device, we demonstrate the potential to discriminate CP light with a fast light response time and with a very high photocurrent dissymmetry factor (<i>g<sub>ph</sub></i> = ±1.35). Our study thus provides key strategies to design fullerenes with large chiroptical responses for use as single enantiomer components of organic electronic devices. We anticipate that our data will position chiral fullerenes as an exciting material class for the growing field of chiral electronic technologies.</p></jats:p>
Schmidt J, Weatherby JA, Sugden I, et al., 2020, Computational Screening of Organic Semiconductors: Exploring Side-Group Functionalisation and Assembly to Optimise Charge Transport in Chiral Molecules, Publisher: American Chemical Society (ACS)
<jats:p><p>Molecular materials are challenging to design as their packing arrangement and hence properties are subject to subtle variations in the interplay of soft intermolecular interactions that are difficult to predict. The rational design of new molecular materials with tailored properties is currently hampered by the lack of knowledge of how a candidate molecule will pack in space and how we can control the polymorphs we can experimentally obtain. Here, we develop a simplified approach to aid the material design process, by the development of a screening process that is used to test 1344 helicene molecules that have potential as organic electronic materials. Our approach bridges the gap between single molecule design, molecular assembly, and the resulting charge-carrier mobilities. We find that fluorination significantly improves electron transport in the molecular material by up to 200%; the reference helicene packing showed a mobility of 0.30 cm2 V-1 s-1, fluorination increased the mobility to up to 0.96 and 0.97 (13-fluoroH and 4,13-difluoroH), assuming an outer reorganisation energy of 0.30 eV. Side groups containing triple bonds largely lead to improved transfer integrals. We validate our screening approach through the use of crystal structure prediction to confirm the presence of favourable packing motifs to maximize charge mobility.</p></jats:p>
Gerkman MA, Gibson RSL, Calbo J, et al., 2020, Arylazopyrazoles for long-term thermal energy storage and optically-triggered heat release below 0 °C, Journal of the American Chemical Society, Vol: 142, Pages: 8688-8695, ISSN: 0002-7863
Arylazopyrazole derivatives based on four core structures (4pzMe, 3pzH, 4pzH, and 4pzH-F2) and functionalized with a dodecanoate group were demonstrated to store thermal energy in their metastable Z isomer liquid phase and release the energy by optically triggered crystallization at −30 ℃ for the first time. Three heat storage-release schemes were discovered involving different activation methods (optical, thermal, or combined) for generating liquid-state Z isomers capable of storing thermal energy. Visible light irradiation induced the selective crystallization of the liquid phase via Z-to-E isomerization, and the latent heat stored in the liquid Z isomers was preserved for longer than two weeks unless optically triggered. Up to 92 kJ/mol of thermal energy was stored in the compounds demonstrating remarkable thermal stability of Z isomers at high temperatures and liquid-phase stability at temperatures below 0 ℃.
Rueda-Zubiaurre A, Yahiya S, Fischer O, et al., 2020, Structure-activity relationship studies of a novel class of transmission blocking antimalarials targeting male gametes., Journal of Medicinal Chemistry, Vol: 63, Pages: 2240-2262, ISSN: 0022-2623
Malaria is still a leading cause of mortality among children in the developing world, and despite the immense progress made in reducing the global burden, further efforts are needed if eradication is to be achieved. In this context, targeting transmission is widely recognized as a necessary intervention towards that goal. After carrying out a screen to discover new transmission-blocking agents, herein we report our medicinal chemistry efforts to study the potential of the most robust hit, DDD01035881, as a male-gamete targeted compound. We reveal key structural features for the activity of this series and identify analogues with greater potency and improved metabolic stability. We believe this study lays the groundwork for further development of this series as a transmission blocking agent.
Kurz W, Yetisen AK, Kaito MV, et al., 2020, UV-Sensitive Wearable Devices for Colorimetric Monitoring of UV Exposure, ADVANCED OPTICAL MATERIALS, Vol: 8, ISSN: 2195-1071
Calbo J, Thawani AR, Gibson RSL, et al., 2019, A combinatorial approach to improving the performance of azoarene photoswitches, BEILSTEIN JOURNAL OF ORGANIC CHEMISTRY, Vol: 15, Pages: 2753-2764, ISSN: 1860-5397
Wan L, Wade J, Salerno F, et al., 2019, Inverting the handedness of circularly polarized luminescence from light-emitting polymers using film thickness, ACS Nano, Vol: 13, Pages: 8099-8105, ISSN: 1936-0851
The emission of circularly polarized light is central to many applications, including data storage, optical quantum computation, biosensing, environmental monitoring, and display technologies. An emerging method to induce (chiral) circularly polarized (CP) electroluminescence from the active layer of polymer light-emitting diodes (polymer OLEDs; PLEDs) involves blending achiral polymers with chiral small-molecule additives, where the handedness/sign of the CP light is controlled by the absolute stereochemistry of the small molecule. Through the in-depth study of such a system we report an interesting chiroptical property: the ability to tune the sign of CP light as a function of active layer thickness for a fixed enantiomer of the chiral additive. We demonstrate that it is possible to achieve both efficient (4.0 cd/A) and bright (8000 cd/m2) CP-PLEDs, with high dissymmetry of emission of both left-handed (LH) and right-handed (RH) light, depending on thickness (thin films, 110 nm: gEL = 0.51, thick films, 160 nm: gEL = -1.05, with the terms "thick" and "thin" representing the upper and lower limits of the thickness regime studied), for the same additive enantiomer. We propose that this arises due to an interplay between localized CP emission originating from molecular chirality and CP light amplification or inversion through a chiral medium. We link morphological, spectroscopic, and electronic characterization in thin films and devices with theoretical studies in an effort to determine the factors that underpin these observations. Through the control of active layer thickness and device architecture, this study provides insights into the mechanisms that result in CP luminescence and high performance from CP-PLEDs, as well as demonstrating new opportunities in CP photonic device design.
Gibson R, Calbo J, Fuchter MJ, 2019, Chemical Z‐E isomer switching of arylazopyrazoles using acid, ChemPhotoChem, Vol: 3, Pages: 372-377, ISSN: 2367-0932
Arylazopyrazoles show significant potential as next‐generation photoswitches, in particular because of the high thermal stability of their Z‐isomers. Herein we investigate the potential to perform Z−E isomer chemical switching of arylazopyrazoles using acid. We show that acid‐accelerated isomerisation allows for robust Z−E switching using mild acids and opens up the possibility to use light‐acid cycles to near quantitatively and reversibly switch the arylazopyrazoles at room temperature. We attribute the chemical switching to azonium formation, facilitated by mesomeric stabilisation by the pyrazole ring. Coupled with their exceptionally long Z‐isomer half‐lives, we believe our study may open up a wider array of functional opportunities for the arylazopyrazoles.
Yahiya S, Rueda-Zubiaurre A, Delves MJ, et al., 2019, The antimalarial screening landscape-looking beyond the asexual blood stage, CURRENT OPINION IN CHEMICAL BIOLOGY, Vol: 50, Pages: 1-9, ISSN: 1367-5931
Bardell-Cox O, White AJP, Aragón L, et al., 2019, Synthetic studies on the reverse antibiotic natural products, the nybomycins, MedChemComm, Vol: 10, Pages: 1438-1444, ISSN: 2040-2503
Antimicrobial resistance (AMR) is a serious issue that could have severe consequences if steps are not taken. The nybomycin natural products have the potential to extend the clinical efficacy of the marketed fluoroquinolone class of antibiotics through a ‘reverse antibiotic’ approach. However, only very limited structure–activity relationships are known for these fascinating compounds, in part due to challenges with their synthesis. Here we report a new scalable and robust synthetic route to the nybomycin natural products to aid in the development of this series. Through this synthesis, we report the antibiotic activity of novel analogues of this family confirming the selectivity for fluoroquinolone resistant bacteria and potential future opportunities for further optimisation.
Mercea DM, Howlett MG, Piascik AD, et al., 2019, Enantioselective reduction of N-alkyl ketimines with frustrated Lewis pair catalysis using chiral borenium ions, Chemical Communications, Vol: 55, Pages: 7077-7080, ISSN: 1359-7345
Enantioselective reduction of ketimines was demonstrated using chiral N-heterocyclic carbene (NHC)-stabilised borenium ions in frustrated Lewis pair catalysis. High levels of enantioselectivity were achieved for substrates featuring secondary N-alkyl substituents. Comparative reactivity and mechanistic studies identify key determinants required to achieve useful enantioselectivity and represent a step forward in the further development of enantioselective FLP methodologies.
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