Polar Side Chains Research Articles

Electromembrane extraction of peptides based on hydrogen bond interactions

BackgroundElectromembrane extraction (EME) of peptides reported in the scientific literature involve transfer of net positively charged peptides from an aqueous sample, through a liquid membrane, and into an aqueous acceptor solution, under the influence of an electrical field. The liquid membrane comprises an organic solvent, containing an ionic carrier. The purpose of the ionic carrier is to facilitate peptide solvation in the organic solvent based on ionic interactions. Unfortunately, ionic carriers increase the conductivity of the liquid membrane; the current in the system increases, the electrolysis in sample and acceptor is accelerated, and the extraction system tend to be unstable and suffers from drifting pH. ResultsIn the present work, a broad selection of organic solvents were tested as pure liquid membrane for EME of peptides, without ionic carrier. Several phosphates provided high mass transfer, and tri(pentyl) phosphate was selected since this solvent also provided high operational stability. Among 16 different peptides used as model analytes, tri(pentyl) phosphate extracted those with net charge +1 and with no more than two polar side chains. Tri(pentyl) phosphate served as a very strong hydrogen bond acceptor, while the protonated peptides were hydrogen bond donors. By such, hydrogen bonding served as the primary interactions responsible for mass transfer. Tri(pentyl) phosphate as liquid membrane, could exhaustively extract leu-enkephalin, met-enkephalin, and endomorphin from human blood plasma and detected by LC-MS/MS. Calibration curves were linear (r2 > 0.99) within a concentration range from 1 to 500 ng/mL, and a relative standard deviation within 12% was observed for precision studies. SignificanceThe current experiments are important because they indicate that small peptides of low polarity may be extracted selectively in EME based on hydrogen bond interactions, in systems not suffering from electrolysis.

Transient water wires mediate selective proton transport in designed channel proteins.

Selective proton transport through proteins is essential for forming and using proton gradients in cells. Protons are conducted along hydrogen-bonded 'wires' of water molecules and polar side chains, which, somewhat surprisingly, are often interrupted by dry apolar stretches in the conduction pathways, inferred from static protein structures. Here we hypothesize that protons are conducted through such dry spots by forming transient water wires, often highly correlated with the presence of the excess protons in the water wire. To test this hypothesis, we performed molecular dynamics simulations to design transmembrane channels with stable water pockets interspersed by apolar segments capable of forming flickering water wires. The minimalist designed channels conduct protons at rates similar to viral proton channels, and they are at least 106-fold more selective for H+ over Na+. These studies inform the mechanisms of biological proton conduction and the principles for engineering proton-conductive materials.

Side-Chain Modification in Conjugated Polymer Frameworks for the Electrocatalytic Oxygen Evolution Reaction.

Conjugated polymer frameworks (CPFs) have recently sparked tremendous research interest due to their broad potentials in various frontline application areas such as photocatalysis, sensing, gas storage, energy storage, etc. These framework materials, without sidechains or functional groups on their backbone, are generally insoluble in common organic solvents and less solution processable for further device applications. There are few reports on metal-free electrocatalysis, especially oxygen evolution reaction (OER) using CPF. Herein, we have developed two triazine-based donor-acceptor conjugated polymer frameworks by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different sidechains, alkyl and oligoethylene glycol, were rationally introduced into the 3-position of thiophene in the polymer framework to investigate the effect of side-chain functionality on the electrocatalytic property. Both the CPFs demonstrated superior electrocatalytic OER activity and long-term durability. The electrocatalytic performance of CPF2, which achieved a current density of 10 mA/cm2 at an overpotential (η) of 328 mV, is much superior to CPF1, which reached the same current density at an overpotential of 488 mV. The porous and interconnected nanostructure of the conjugated organic building blocks, which allowed for fast charge and mass transport processes, could be attributed to the higher electrocatalytic activity of both CPFs. However, the superior activity of CPF2 compared to CPF1 may be due to the presence of a more polar oxygen-containing ethylene glycol side chain, which enhances the surface hydrophilicity, promotes better ion/charge and mass transfer, and increases the accessibility of the active sites toward adsorption through lower π-π stacking compared to hexyl side chain present in CPF1. The DFT study also supports the plausible better performance toward OER for CPF2. This study confirms the promising potentiality of metal-free CPF electrocatalysts for OER and further sidechain modification to improve their electrocatalytic property.

Organic Thermoelectric Materials from n-Type Polymer Semiconductors.

Organic thermoelectric (OTE) materials have aroused increasing attention due to their potential application in wearable/flexible TE generator for energy harvesting. To meet the practical application of thermoelectric device, high-performance p- and n-type OTE materials are both necessary. In the past few years, n-type polymer semiconductors have witnessed the rapid development in OTE field, however, their thermoelectric performance isstill lagging behind p-type counterparts. Therefore, more efforts should be made to enhance n-type polymer TE performance, including development of novel molecule structure, synthesis of new dopants and optimization of device engineering. In this review, we highlight the effects of molecular structure and side chain length and polarity of n-type polymer semiconductors on the TE performance such as electron transport, electrical conductivity, and power factor. Finally, further perspective and challenge are also discussed to provide useful guideline for the design of high-performance n-type OTE materials.

Conserved loop residues−Tyr270 and Asn372 near the catalytic site of the lysostaphin endopeptidase are essential for staphylolytic activity toward pentaglycine binding and catalysis

Lysostaphin endopeptidase cleaves pentaglycine cross-bridges found in staphylococcal cell-wall peptidoglycans and proves very effective in combatting methicillin-resistant Staphylococcus aureus. Here, we revealed the functional importance of two loop residues, Tyr270 in loop 1 and Asn372 in loop 4, which are highly conserved among the M23 endopeptidase family and are found close to the Zn2+-coordinating active site. Detailed analyses of the binding groove architecture together with protein-ligand docking showed that these two loop residues potentially interact with the docked ligand–pentaglycine. Ala-substituted mutants (Y270A and N372A) were generated and over-expressed in Escherichia coli as a soluble form at levels comparable to the wild type. A drastic decrease in staphylolytic activity against S. aureus was observed for both mutants, suggesting an essential role of the two loop residues in lysostaphin function. Further substitutions with an uncharged polar Gln side-chain revealed that only the Y270Q mutation caused a dramatic reduction in bioactivity. In silico predicting the effect of binding site mutations revealed that all mutations displayed a large ΔΔGbind value, signifying requirements of the two loop residues for efficient binding to pentaglycine. Additionally, MD simulations revealed that Y270A and Y270Q mutations induced large flexibility of the loop 1 region, showing markedly increased RMSF values. Further structural analysis suggested that Tyr270 conceivably participated in the oxyanion stabilization of the enzyme catalysis. Altogether, our present study disclosed that two highly conserved loop residues, loop 1-Tyr270 and loop 4-Asn372, located near the lysostaphin active site are crucially involved in staphylolytic activity toward binding and catalysis of pentaglycine cross-links.

Constructing Novel High-Performance Dipolar Glass Polymer Dielectrics by Polar Rigid/Flexible Side Chains.

Developing new polymer dielectrics with superior dielectric and energy storage properties is urgent to meet the demand for electronic devices in the field of microminiaturization or harsh environments. In this paper, two dipolar glass polymers based on polynorbornene main chain and flexible/rigid cyano side chain were synthesized by ring opening metathesis polymerization method: polymer PCEMT with flexible side chains and polymer PCPMT with rigid side chains. The backbone is built from two rigid five-membered rings, which not only avoids the narrow band gap caused by π-π conjugation of traditional aromatic main chains, but also maintains high thermal stability and high glass transition temperature (Tg). The introduced polar cyano groups on the side chain gave high dielectric constants (εr) for both polymers, where the εr of PCEMT and PCPMT reached 7.9 and 4.6 at room temperature and 1 kHz, respectively. Due to high polarization and high breakdown strength, the PCPMT obtains a maximum discharge energy density (Ud) of 4.47 J/cm3 at room temperature, which is 1.61 and 1.57 times of biaxially oriented polypropylene and polyimide (Kapton). The supernal Tg of 229 °C makes the energy storage performance of PCPMT almost unaffected at 100 °C. The charge-discharge efficiency (η) always keeps over 90% and an Ud of 5.2 J/cm3 at 480 MV/m is achieved, which is much better than Kapton (Ud = 1.77 J/cm3, η = 42.5%) under the same conditions. This work provides a new idea for preparing the high-performance polymer dielectrics via introducing rigid polar side chains.

Regioisomeric Cyanated Polythiophenes Bearing Polar Side Chains for n-Type Organic Thermoelectrics

The development of n-type polymers with high thermoelectric performance remains a major challenge for organic thermoelectrics. Herein, by devising two new isomeric cyano-functionalized bithiophene building blocks bearing polar side chains, we report two novel donor–acceptor-configurated n-type polythiophene polymers (BTOgCN-FT and BTCNOg-FT) with regiochemically tuned intramolecular S···O noncovalent interactions (INIs) and cyanation patterns for n-type thermoelectric application. The results show that cyanation furnished low-lying LUMO energy levels approaching that of the benchmark n-type polymer N2200 for both polymers (∼−3.90 eV), which combine with their polar side chain-enabled high dopant miscibility, leading to efficient n-doping efficiencies. Detailed theoretical and experimental studies also suggest that BTOgCN-FT exhibited a more planar backbone conformation and more ordered interchain packing in film state, thus yielding higher electrical values than BTCNOg-FT. Therefore, the polymer BTOgCN-FT eventually displays an optimal power factor (PF) value of 2.77 μW m–1 K–2, which is higher than that of BTCNOg-FT (1.50 μW m–1 K–2) and also largely outperforming that of the thoroughly investigated and optimized polymer N2200 (typical PF value of 10–2 μW m–1 K–2). Our work not only presents two novel structurally simple and isomeric electron-accepting building blocks but also offers valuable structure–property correlations for the future design of high-performance n-type thermoelectric materials.

A novel davunetide (NAPVSIPQQ to NAPVSIPQE) point mutation in activity-dependent neuroprotective protein (ADNP) causes a mild developmental syndrome.

NAP (NAPVSIPQ, drug candidate name, davunetide) is the neuroprotective fragment of activity-dependent neuroprotective protein (ADNP). Recent studies identified NAPVSIP as a Src homology 3 (SH3) domain-ligand association site, responsible for controlling signalling pathways regulating the cytoskeleton. Furthermore, the SIP motif in NAP/ADNP was identified as crucial for direct microtubule end-binding protein interaction facilitating microtubule dynamics and Tau microtubule interaction, at the microtubule end-binding protein site EB1 and EB3. Most de novo ADNP mutations reveal heterozygous STOP or frameshift STOP aberrations, driving the autistic/intellectual disability-related ADNP syndrome. Here, we report for the first time on a de novo missense mutation, resulting in ADNP containing NAPVISPQE instead of NAPVSIPQQ, in a child presenting developmental hypotonia, possibly associated with inflammation affecting food intake in early life coupled with fear of peer interactions and suggestive of a novel case of the ADNP syndrome. In silico modelling showed that the mutation Q (polar side chain) to E (negative side chain) affected the electrostatic characteristics of ADNP (reducing, while scattering the electrostatic positive patch). Comparison with the most prevalent pathogenic ADNP mutation, p.Tyr719*, indicated a further reduction in the electrostatic patch. Previously, exogenous NAP partially ameliorated deficits associated with ADNP p.Tyr719* mutations in transfected cells and in CRISPR/Cas9 genome edited cell and mouse models. These findings stress the importance of the NAP sequence in ADNP and as a future putative therapy for the ADNP syndrome.

Molecularly Hybridized Conduction in DPP-Based Donor-Acceptor Copolymers toward High-Performance Iono-Electronics.

Iono-electronics, that is, transducing devices able to translate ionic injection into electrical output, continue to demand a variety of mixed ionic-electronic conductors (MIECs). Though polar sidechains are widely used in designing novel polymer MIECs, it remains unclear to chemists how much balance is needed between the two antagonistic modes of transport (ion permeability and electronic charge transport) to yield high-performance materials. Here, the impact of molecularly hybridizing ion permeability and charge mobility in semiconducting polymers on their performance in electrochemical and synaptic transistors is investigated. A series of diketopyrrolopyrrole (DPP)-based copolymers are employed to demonstrate the multifunctionality attained by controlling the density of polar sidechains along the backbone. Notably, efficient electrochemical signal transduction and reliable synaptic plasticity are demonstrated via controlled ion insertion and retention. The newly designed DPP-based copolymers further demonstrate unprecedented thermal tolerance among organic mixed ionic-electronic conductors, a key property in the manufacturing of organic electronics.

Mechanisms by which water-mediated hydrogen-bond networks govern pH-dependent reactions at membrane interfaces.

pH-dependent reactions at membrane interfaces are used by cells to maintain pH homeostasis and to ensure normal cell function. Membrane-bound proteins and peptide systems that sense pH typically bind protons using a few titratable sidechains that communicate with the bulk. The identity of these pH-sensing sidechains is central to hypotheses about protein reaction mechanisms and for the rational design of proton detectors. But, as protein groups hypothesized to sense pH in proteins and peptide systems are part of dynamic water-mediated networks, evaluating their pH-sensing functionality may prove difficult. We developed efficient graph-based algorithms and methodologies to evaluate dynamic hydrogen-bond networks of protein and peptide systems known to have a pH-sensing functionality, and to identify sites of hydrogen-bond networks where protons are likely to bind. We find that the assembly of dynamic water-mediated hydrogen-bond networks that include potential proton-sensing groups is a key event along the reaction coordinates of pH-dependent membrane proteins and membrane-bound peptides, and implement graph-based algorithms to characterize the dynamics of these water networks. We further find that polar and basic protein sidechains largely govern the dynamics of the water-mediated hydrogen-bond networks of proton-binding groups, and help maintain acidic sidechains within clusters that collectively can bind and store protons. Taken together, the ensemble of hydrogen-bond network computations we performed for pH-coupled proteins and peptide systems provide a framework to decipher the roles of dynamic water-mediated hydrogen-bond networks in proton binding at membrane interfaces. Research was supported in part by the European Union's Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie grant agreement No 860592, Innovative Training Network ‘Proton and proton-coupled transport’, and by computing time from the Physics Department of the Freie Universität Berlin and from the Forschungszentrum Jülich (JURECA-DC, allocation PHDPORES).

The role of myosin loop-4 in localizing tropomyosin on actin during muscle activation and relaxation.

During force-generating steps of the muscle crossbridge cycle, the tip of the myosin motor, namely myosin loop-4, contacts the tropomyosin cable of actin filaments. In the current study, we determined the corresponding effect of myosin loop-4 on the regulatory positioning of tropomyosin on actin. To accomplish this, we compared high-resolution cryo-EM structures of myosin S1-decorated thin filaments containing either wild-type or a loop-4 mutant construct. In the mutant, the seven-residue portion of myosin loop-4 that contacts tropomyosin was replaced by glycine residues, thus removing polar side chains from residues 366 to 372. Cryo-EM analysis of fully-decorated actin-tropomyosin filaments with either wild-type or mutant S1, yielded 3.4- to 3.6-Å resolution reconstructions, with even higher definition at the actin-myosin interface. Loop-4 densities both in wild-type and mutant S1 were clearly identified, and side chains were resolved in the wild-type structure. Aside from loop-4, actin and myosin structural domains were indistinguishable from each other. In marked contrast, the position of tropomyosin on actin in the two reconstructions differed by 3 to 4 Å. In maps of the mutant, tropomyosin was located closer to the myosin-head and thus moved in the direction of the C-state conformation adopted by myosin-free thin filaments. Complementary interaction energy measurements showed that tropomyosin in the mutant thin filaments sits on actin in a local energy minimum site, whereas tropomyosin is positioned by wild-type S1 in an energetically unfavorable location. We propose that the relatively high potential energy associated with wild-type tropomyosin positioning favors an effective transition to B- and C-states following release of myosin from thin filaments during relaxation.

Sulfone-Modified Perylene Acceptors with Improved Permittivity for Bilayer Organic Solar Cells Processed from Non-halogenated Solvents

Organic photovoltaics show high promise as a technology for sustainable energy conversion. A prominent strategy to reduce the substantial energy loss of organic solar cells is to synthesize high-permittivity (high-ε) active layer materials. However, despite the increase in permittivity, many of the high-ε materials achieved only inferior efficiencies, which is generally explained with a worse bulk heterojunction morphology. In this work, we tackled this issue by preparing high-ε acceptors and incorporating them in a bilayer setup, which we optimized using the systematic Design of Experiment (DoE) approach. The prepared acceptors are based on a perylene-linker-perylene scaffold, to which we attached polar sulfone-containing side chains. The relative permittivity of these acceptors increased by over 50% compared to their alkylated analogues. Simultaneously, some of the acceptors have greatly improved solubilities in non-halogenated “green” solvents. Both improvements enabled us to build bilayer organic solar cells from o-xylene and THF with PTQ10 as the donor, while simultaneously increasing the efficiency to 5.51% with a high open-circuit voltage of 1.3 V. Our results show that using a bilayer setup can successfully prevent morphology-related efficiency losses when employing high-ε materials. Combining this approach with a systematic optimization method (DoE) can unlock the theoretical potential of permittivity modification in organic solar cell research.

ScrepYard: an online resource for disulfide-stabilised tandem repeat peptides.

Receptor avidity through multivalency is a highly sought-after property of ligands. While readily available in nature in the form of bivalent antibodies, this property remains challenging to engineer in synthetic molecules. The discovery of several bivalent venom peptides containing two homologous and independently folded domains (in a tandem repeat arrangement) has provided a unique opportunity to better understand the underpinning design of multivalency in multimeric biomolecules, as well as how naturally occurring multivalent ligands can be identified. In previous work we classified these molecules as a larger class termed secreted cysteine-rich repeat-proteins (SCREPs). Here, we present an online resource; ScrepYard, designed to assist researchers in identification of SCREP sequences of interest and to aid in characterizing this emerging class of biomolecules. Analysis of sequences within the ScrepYard reveals that two-domain tandem repeats constitute the most abundant SCREP domain architecture, while the interdomain "linker" regions connecting the functional domains are found to be abundant in amino acids with short or polar sidechains and contain an unusually high abundance of proline residues. Finally, we demonstrate the utility of ScrepYard as a virtual screening tool for discovery of putatively multivalent peptides, by using it as a resource to identify a previously uncharacterised serine protease inhibitor and confirm its predicated activity using an enzyme assay. This article is protected by copyright. All rights reserved.

Poly (aryl piperidinium) membranes with dipolar alkyl nitrile sidechains for fuel cells

Several poly (biphenyl piperidine-trifluoroacetophenone) based polymers with different grafting ratios of polar alkyl nitrile side chains are synthesized, named PBPAp-PN-x. The relationship between structure and performance is studied, including conductivity, swelling ratio (SR), morphology, single-cell performance, etc. The SR and conductivity at 80 °C of PBPAp-PN30% are 41.0% and 142.3 mS cm−1, whereas those of PBPAp-PN0% are 77.8% and 155.3 mS cm−1, respectively. Further, molecular dynamics (MD) simulations are carried out to microcosmically reveal the mechanism of structure-property relationship, which simulate the number of water molecules (NH2O) and the diffusion coefficients (D). The simulations also indicate polar cyanide groups can form close contacts, which is similar to physical crosslinking to inhibit the swelling of backbone. As a result, the advantage of grafting dipolar molecules in AEMs not only effectively resolves the “trade-off” problem between ionic conductivity and dimensional stability, but also might be a promising application in fuel cells.

Structure of SALL4 zinc finger domain reveals link between AT-rich DNA binding and Okihiro syndrome.

Spalt-like 4 (SALL4) maintains vertebrate embryonic stem cell identity and is required for the development of multiple organs, including limbs. Mutations in SALL4 are associated with Okihiro syndrome, and SALL4 is also a known target of thalidomide. SALL4 protein has a distinct preference for AT-rich sequences, recognised by a pair of zinc fingers at the C-terminus. However, unlike many characterised zinc finger proteins, SALL4 shows flexible recognition with many different combinations of AT-rich sequences being targeted. SALL4 interacts with the NuRD corepressor complex which potentially mediates repression of AT-rich genes. We present a crystal structure of SALL4 C-terminal zinc fingers with an AT-rich DNA sequence, which shows that SALL4 uses small hydrophobic and polar side chains to provide flexible recognition in the major groove. Missense mutations reported in patients that lie within the C-terminal zinc fingers reduced overall binding to DNA but not the preference for AT-rich sequences. Furthermore, these mutations altered association of SALL4 with AT-rich genomic sites, providing evidence that these mutations are likely pathogenic.

Aqueous processing of organic semiconductors enabled by stable nanoparticles with built-in surfactants.

The introduction of oligoether side chains onto a polymer backbone can help to stabilise polymeric dispersions in water without the necessity of surfactants or additives when conjugated polymer nanoparticles are prepared. A series of poly(3-hexylthiophene) (P3HT) derivatives with different content of a polar thiophene derivative 3-((2-methoxyethoxy)methyl)thiophene was interrogated to find the effect of the polar chains on the stability of the formed nanoparticles, as well as their structural, optical, electrochemical, and electrical properties. Findings indicated that incorporation of 10-20 percent of the polar side chain led to particles that are stable over a period of 42 days, with constant particle size and polydispersity, however the particles from the polymer with 30 percent polar side chain showed aggregation effects. The polymer dispersions showed a stronger solid-like behaviour in water with decreasing polar side chain content, while thin film deposition from water was found to afford globular morphologies and crystallites with more isotropic orientation compared to conventional solution-processed films. As a proof-of-principle, field-effect transistors were fabricated directly from the aqueous dispersions demonstrating that polymers with hydrophilic moieties can be processed in water without the requirement of surfactants.

Catechol-free ternary random copolymers for strong and repeatable underwater adhesion

Ternary random copolymers consisting of chemical features of nonphenolic aromatic groups, cations, and polar side chains enabled excellent underwater adhesion.

A novel method for in silico assessment of Methionine oxidation risk in monoclonal antibodies: Improvement over the 2-shell model.

Over the past decade, therapeutic monoclonal antibodies (mAbs) have established their role as valuable agents in the treatment of various diseases ranging from cancers to infectious, cardiovascular and autoimmune diseases. Reactive groups of the amino acids within these proteins make them susceptible to many kinds of chemical modifications during manufacturing, storage and in vivo circulation. Among these reactions, the oxidation of methionine residues to their sulfoxide form is a commonly observed chemical modification in mAbs. When the oxidized methionine is in the complementarity-determining region (CDR), this modification can affect antigen binding and thus abrogate biological activity. For these reasons, it is essential to identify oxidation liabilities during the antibody discovery and development phases. Here, we present an in silico method, based on protein modeling and molecular dynamics simulations, to predict the oxidation-liable residues in the variable region of therapeutic antibodies. Previous studies have used the 2-shell water coordination number descriptor (WCN) to identify methionine residues susceptible to oxidation. Although the WCN descriptor successfully predicted oxidation liabilities when the residue was solvent exposed, the method was much less accurate for partially buried methionine residues. Consequently, we introduce a new descriptor, WCN-OH, that improves the accuracy of prediction of methionine oxidation susceptibility by extending the theoretical framework of the water coordination number to incorporate the effects of polar amino acids side chains in close proximity to the methionine of interest.

Triazine and Thiophene-Containing Conjugated Polymer Network Emitter-Based Solution-Processable Stable Blue Organic LEDs

The development of solution-processable fluorescent materials with blue electroluminescence has recently attracted considerable research interest for organic light-emitting diode (OLED) applications. Whereas, conjugated polymer frameworks (CPFs) or networks (CPNs) have attained tremendous research interest due to their vast potential in a variety of cutting-edge applications including photocatalysis, sensing, gas storage, energy storage, and so on. These framework/network materials without side chains or functional groups on their backbone are generally insoluble in common organic solvents and less solution-processable for electronic device applications. Herein, we have reported two triazine-based highly fluorescent and wide-band gap donor–acceptor conjugated polymer networks (CPNs) by coupling a 3-substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different side chains, alkyl and oligoethylene glycol, are rationally introduced into the 3-position of thiophene in the polymer network to make them solution-processable. Further physicochemical and optoelectronic characterizations of these emitters are performed in detail, and the effects of the side chain functionality and polarity on the above-mentioned properties are also thoroughly investigated. OLEDs based on these CPNs as emitters show a maximum external quantum efficiency of 2.3% with a maximum brightness of 2541 cd/m2 and a maximum current efficiency of 2.8 cd/A with blue emission [Commission Internationale de l’éclairage (CIE) coordinates of (0.17, 0.19)]. To the best of our knowledge, this may be the first example of conjugated polymer network material emitters being successfully designed, fabricated, and tested for solution-processable blue OLEDs. These results also demonstrate the high potential of the conjugated polymer network emitters for future blue or other color OLED applications.

Effects of Side-Chain Length and Functionality on Polar Poly(dioxythiophene)s for Saline-Based Organic Electrochemical Transistors.

Understanding the impact of side chains on the aqueous redox properties of conjugated polymers is crucial to unlocking their potential in bioelectrochemical devices, such as organic electrochemical transistors (OECTs). Here, we report a series of polar propylenedioxythiophene-based copolymers functionalized with glyme side chains of varying lengths as well as an analogue with short hydroxyl side chains. We show that long polar side chains are not required for achieving high volumetric capacitance (C*), as short hydroxy substituents can afford facile doping and high C* in saline-based electrolytes. Furthermore, we demonstrate that varying the length of the polar glyme chains leads to subtle changes in material properties. Increasing the length of glyme side chain is generally associated with an enhancement in OECT performance, doping kinetics, and stability, with the polymer bearing the longest side chains exhibiting the highest performance ([μC*]OECT = 200 ± 8 F cm-1 V-1 s-1). The origin of this performance enhancement is investigated in different device configurations using in situ techniques (e.g., time-resolved spectroelectrochemistry and chronoamperometry). These studies suggest that the performance improvement is not due to significant changes in C* but rather due to variations in the inferred mobility. Through a thorough comparison of two different architectures, we demonstrate that device geometry can obfuscate the benchmarking of OECT active channel materials, likely due to contact resistance effects. By complementing all electrochemical and spectroscopic experiments with in situ measurements performed within a planar OECT device configuration, this work seeks to unambiguously assign material design principles to fine-tune the properties of poly(dioxythiophene)s relevant for application in OECTs.