Perfluoroalkyl acids are a subclass of persistent toxic per- and polyfluoroalkyl substances (PFAS) whose volatility enables airborne exposure pathways that remain largely unmonitored. Therefore, suitable technologies are urgently needed for real-time monitoring of PFAS acids in the vapor phase. Herein, we report a new platform for selective vapor-phase detection of volatile perfluoroalkyl acids using amplifying fluorescent polymers. The designs incorporate highly fluorinated moieties to create a fluorous microenvironment that enhances selectivity and pyridine-based selectors that react with volatile PFAS acids through proton-transfer reactions. Ratiometric fluorescence detection was employed in sensing experiments, and polymer thin films exhibited rapid responses (<5 s) to PFAS acids vapor exposure, with the induced signal persisting for more than 15 min. The polymer C8/C4PF-Py emerged as the most sensitive material, exhibiting vapor-phase detection limits of 47.8 ppm, 2.38 ppm, and 450 ppb for TFA, PFBA, and GenX, respectively. This work establishes a versatile, rapid, and selective platform for vapor-phase detection of PFAS acids. The materials can be coated on a variety of surfaces, and their fluorescence changes can be easily monitored, thereby reducing expensive instrumentation dependence and laboratory testing, providing a practical pathway toward routine monitoring and regulation of airborne PFAS acids.

Conspectus Excitons are mobile excited states in materials with properties and dynamics that underpin many applications of conjugated organic polymers. Understanding these quasiparticles in organic materials requires knowledge of classical molecular photophysics and solid-state physics-based descriptions of semiconducting polymers. The molecular interpretation of an exciton is an excited state with physical size determined by the region over which bond lengths/angles are relaxed from their equilibrium ground state geometries. The physics representation is that excitons are quasiparticles comprising a bound electron–hole pair. Specifically, in the excited state the hole is a vacancy in the HOMO (valence band) and the electron is an unpaired electron in the LUMO (conduction band). Excitons move through multiple mechanisms. These include Förster energy transfer wherein the dipole from a virtual electronic emission is captured by a coupled chromophore to create a new excited state. The Förster mechanism is facilitated by the natural tendency of the high aspect ratio of conjugated polymer chromophores to align, the relatively low dielectric constant of the materials, and the high spectral overlap of the absorptions and emissions. In a second mechanism, the exciton moves through band transport, wherein thermal phonons (traveling compression/expansion nuclear motion excitations) nudge the excitons and cause movement. This mechanism requires direct orbital interactions (strong electronic coupling) and is related to Dexter energy transfer in the molecular systems, wherein collisional interactions between molecules allow for energy transfer. Both molecular and solid-state physics perspectives are valuable in understanding exciton dynamics/mobility. Exciton transport is central to photovoltaics and photodetectors excitons wherein these electron–hole pairs diffuse to interfaces and separate to create electrical potentials and/or photocurrents. Ultrasensitive chemical sensors and biosensors based on conjugated organic polymers exhibit amplified sensor responses enabled by exciton diffusion. This natural amplification has been widely exploited for trace chemical and biological sensing, and explosive sensors have been commercial now for more than 20 years based on this principle. Moreover, the polychromophore character of conjugated organic polymers creates very large absorption cross sections and when combined with high emission quantum yields makes them exceptionally bright fluorescent labels, which has found use in biology. Exciton diffusion enhances photoredox catalysis wherein fast exciton diffusion increases the probably of encounter of the reactive excited state within a nanosecond timeline. My studies of excitons have been guided by classical physical organic chemistry wherein hypotheses are tested through materials design and synthesis. I will detail how receptor integration, control of interpolymer organization, precision assembly of aligned polymers, and modulation of excited state lifetimes have provided understanding and empowered key applications.

N-Nitrosodimethylamine (NDMA) is a water-soluble carcinogen typically quantified using mass spectrometry coupled with chromatographic separation, which requires extensive sample preparation and sophisticated instrumentation. Here, we report a fluorescence-based detection strategy for NDMA in aqueous media that replaces column-based separation with affinity capture. Photochemical transformation of NDMA, followed by reaction with a biotinylated polymeric reagent, generates a biotin-labeled fluorescent product that can be selectively enriched through streptavidin-biotin interaction, enabling effective separation of the analytical signal from background. The assay is performed entirely in water without sample pretreatment, preconcentration, or solvent exchange. Under optimized conditions, quantitative detection is achieved in a plate-based format using only 100 mu L samples, affording a limit of detection of 235 ppb. The chemical transformation is completed within 22 min, followed by rapid affinity capture via streptavidin-coated agarose beads or plates. The method is rigorously validated through spectroscopic characterization, selective capture experiments, and quantitative analysis, and demonstrates consistent performance in spiked commercial water samples. These results establish a chemically defined platform for chromatography-independent optical NDMA detection and provide a basis for further development toward scalable sensing formats built on streptavidin-functionalized solid phases.

Open shell luminescent organic molecules have been gaining attention in recent years for their ability to access different excited state manifolds compared to their closed shell congeners. However, there has been little work to expand the design of these systems beyond direct conjugation strategies. Herein, we report the synthesis, and optical and magnetic characterization of two new triarylmethyl radical compounds that interact via a remote homoconjugation with a donor group through a [2.2.2] bridge. The properties of these bridged radicals are compared to those of a non-bridged species. This study ultimately expands the design strategies for synthesizing emissive radical species.

Rapid and reliable quantification of bacterial dynamics at the cellular level is critical for pathogen sensing, live-dead bacterial assays, and monitoring of bacteria fitness and viability. Here, we demonstrate bacterial fitness quantification by capturing individual cells on topological defects of micro-scale liquid crystal emulsion droplets. The emulsion droplets are composed of phase-separated nematic liquid crystal and fluorocarbon components and exhibit an asymmetric mass distribution. A topological singularity in the director field of the liquid crystal phase localizes tailormade surfactants that tether a single bacterium per droplet. Active motion of the bacterium induces a tilt and azimuthal rotation of the droplet trap, which is counteracted by gravity acting on the droplet center of mass. By comparing the observed dynamics of a tethered bacterium's stochastic movement to a computational model of bacterial motion on spherical surfaces that is based on the classical Ornstein-Uhlenbeck process, we quantify the fitness of bacteria subjected to starvation over several days. This pathogen fitness sensing concept, which relies on the scalable chemical design of single bacterial cell traps, a robust optical readout, and a theoretical understanding of bacterial dynamics on spherical surfaces, offers opportunities for rapid pathogen activity assessment, micro-biological sensing, and biologically powered micro-actuator systems.

N-Nitrosodimethylamine (NDMA) is a water-soluble carcinogen typically quantified using mass spectrometry coupled with chromatographic separation, which requires extensive sample preparation and sophisticated instrumentation. Here, we report a fluorescence-based detection strategy for NDMA in aqueous media that replaces column-based separation with affinity capture. Photochemical transformation of NDMA, followed by reaction with a biotinylated polymeric reagent, generates a biotin-labeled fluorescent product that can be selectively enriched through streptavidin-biotin interaction, enabling effective separation of the analytical signal from background. The assay is performed entirely in water without sample pretreatment, preconcentration, or solvent exchange. Under optimized conditions, quantitative detection is achieved in a plate-based format using only 100 μL samples, affording a limit of detection of 235 ppb. The chemical transformation is completed within 22 min, followed by rapid affinity capture via streptavidin-coated agarose beads or plates. The method is rigorously validated through spectroscopic characterization, selective capture experiments, and quantitative analysis, and demonstrates consistent performance in spiked commercial water samples. These results establish a chemically defined platform for chromatography-independent optical NDMA detection and provide a basis for further development toward scalable sensing formats built on streptavidin-functionalized solid phases.

Polypyrrole is functionalized by deprotonation of its oxidized state, followed by a thiol-Michael addition reaction. It is found that this process produced emissive compositions. This feature is found to be diagnostic of the functionalization and relative solvation by water, wherein enhanced interactions with the solvent gave higher emission intensities. The thiol-conjugation method is shown to be general and can be extended to a range of polar, nonpolar, and aromatic materials. Thiol-conjugated materials retain the electroactivity characteristic of polypyrrole. The dual fluorescence and electroactivity of these thiol-conjugated nanoparticles suggest their potential as a sensing platform.

Presently, error correction of covalent bonds for the controlled synthesis of ordered multidimensional materials is largely restricted to thermal methods, which oftentimes require harsh reaction conditions. This limitation affects interfacial applications, for example, in emulsions that are central to many industrial applications in energy, healthcare, or foods. Herein, we introduce wavelength-orthogonal optodynamics, which enables photoinduced error correction and provides a mild alternative to conventional dynamic covalent chemistry. We demonstrate that the dynamic interplay between two wavelengths (440 and 370 nm) can be harnessed for the preferential cleavage of suboptimal linkages to induce major structural improvements in interfacial polymer shells of emulsions. This overwrites the inherent statistical limitations of conventional photopolymerizations, which traditionally result in highly heterogeneous and defective structures. Overall, the work exemplifies the opportunities of wavelength-orthogonal optodynamic chemistry for the generation and modification of organic materials and highlights the prospect of it to areas previously inaccessible to dynamic covalent synthesis.

Herein, we present the development and evaluation of a molecularly imprinted polymer (MIP) sensor for the sensitive and selective detection of N-nitrosodimethylamine (NDMA) in aqueous environments. MIP coatings over electrochemically active electrodes enable NDMA detection with a notably low detection limit of 1.16 ppb. Our findings demonstrate that the dual-monomer system employed in the MIP fabrication enhances both the selectivity and sensitivity toward NDMA. Additionally, the reversibility of the sensor was confirmed via a chronoamperometry regeneration process. Furthermore, the sensor's robustness was demonstrated across various water samples, as well as on different electrode materials, highlighting its potential for practical and reliable water quality monitoring applications.

The increased mechanical flexibility, solution processability, ease of fabrication, and high Verdet constants have made organic Faraday rotators a promising alternative to conventional inorganic magneto-optical (MO) materials. Despite this, organic Faraday rotators have not been developed to address near-infrared (NIR) MO applications, limiting their device applications. Here, we describe a three-step synthesis and MO characterization of a fused octapyrrolyl cyclooctatetraene (FOPCOT) which exhibits a record high Verdet constant of a small molecule in the NIR-II region. Notably, the cyclooctatetraene core is constructed in a three-step one-pot reaction whereby a N,N'-dipyrrolyl acetylene is generated and immediately reacted with Rosenthal's complex to produce the corresponding zirconacycle intermediate in situ. The cascade is completed with a copper-mediated transmetalation that reductively eliminates to yield the octapyrrolyl cyclooctatetraene. This transformation offers a distinct alternative to conventional methods for pyrrole incorporation into polycyclic aromatic hydrocarbons. Stoichiometric oxidation with AgPF6 affords the oxidized analogues FOPCOT•+ and FOPCOT2+, which display strong optical absorptions at 1743 and 1198 nm, respectively. Magnetic circular dichroism study on spin-coated thin films of FOPCOT2+ yielded a maximum Verdet constant of -2.5 × 105 deg T-1 m-1 at 1224 nm.

Kurzzusammenfassung Die Synthese und Charakterisierung eines ersten Beispiels für ein Ni‐Phthalocyanin (Pc) Hybridmolekül, das vier Hexa‐ peri ‐Hexabenzocoronensubstituenten (HBC) trägt, sowie von drei HBC‐Benzimidazolderivaten ist beschreiben. Die π‐elektronenreichen Chromophore weisen einen hohen molaren Absorptionskoeffizienten mit erweiterter Absorption bis zu 460 nm auf. Insbesondere das HBC‐Pc absorbiert über weite Bereiche des UV‐vis Spektrums; die Pc Q‐Bande befindet sich bei 672 nm. Dies erlaubte die Untersuchung als Faradayrotator, in deren Zuge das Molekül eine beachtliche Verdet‐Konstante von −1.4 × 10 5 deg T −1 m −1 bei 700 nm zeigte, die dem Faraday A‐Term zugewiesen werden konnte. Elektrochemische Messungen, unterstützt von DFT Berechnungen zusammen mit einer Analyse der angeregten Zustände der Molekülorbitale durch TDDFT, erhellen die elektronische Struktur der Moleküle. Das HBC‐Pc zeigt durch das Einfügen des Pc‐Gerüsts einen wesentlich geringeren HOMO‐LUMO Abstand als die übrigen HBC‐basierten Verbindungen.

Easily tunable and processable, porous organic polymers (POPs) have found increasing utility in various applications. Molecular modeling and simulations are invaluable tools in polymer science but remain under-reported in the POP literature. Accurate modeling and simulation of these materials could boost the discovery of high-performance POPs and allow for a more thorough contribution to big data. These polymers contain free volume-promoting structural units, such as iptycenes, and exhibit high glass-transition temperatures, excellent thermal stability, and tunable functionality. However, popular transferable force fields utilized in all-atomistic molecular dynamics (MD) simulations are not fully parametrized for intrinsically porous thermoplastic materials. We present a streamlined workflow for all-atomistic MD simulations of nonporous and porous amorphous polymer materials. In conjunction with the programs ORCA, Q-Force, Assemble!, and GROMACS, a highly accessible methodology is established for force field (FF) parametrization, creation of initial configurations, and simulation of various nonporous and porous polymers. This protocol can reproduce experimental bulk densities and fractional free volume values for amorphous polymeric materials with excellent accuracy and has been made available as a Python package, called PolyPal. As an example, we present our results using PolyPal on a series of nonporous and porous polymers that were previously synthesized and experimentally characterized. FF accuracy was also validated through solid-state NMR studies. These simulations will not only open new avenues for the rational design of high-performance POPs through the contribution of improved insight but also provide a streamlined pathway for simulating previously unexplored porous polymeric materials.

The incorporation of pentiptycene moieties into polymers as a porosity inducing motif has been gaining attention in recent years as a robust strategy to prevent chain packing in the solid state. Herein, we report the synthesis and characterization of pentiptycene containing macromonomers. The halide substituent on the monomers provides access to different polymerization conditions. Macromonomers afford polymers through nucleophilic aromatic substitution, Yamamoto, and Suzuki-Miyaura polymerizations. These polymers are thermally robust as determined by TGA and DSC analysis. BET and WAXS analysis reveal that the pentiptycene moieties contribute substantially to the intrinsic porosity of the final polymer network. These studies also reveal that the nature of the comonomers plays a substantial role in determining the intrinsic porosity.

H2S/CH4 and CO2/CH4 separations show opposing trends, making simultaneous improvement challenging. This is addressed by increasing free volume to enhance competitive sorption effects and boosting diffusion selectivity through in situ crosslinking.

In this paper, we report redox-active azacoronene helicenes obtained through nucleophilic substitution of fluorinated helicenes with 3,4-diethylpyrrole, followed by Scholl reactions. Cyclic voltammetry of these compounds displays reversible oxidation events at low oxidation potentials. The oxidized species display distinct optical properties. Additionally, we incorporated the azacoronene/helicene unit into conjugated polymers.

We report the preparation of poly(ionic) polymer-wrapped single-walled carbon nanotube dispersions for chemiresistive methane (CH4) sensors with improved humidity tolerance. Single-walled CNTs (SWCNTs) were noncovalently functionalized by poly(4-vinylpyridine) (P4VP) with varied amounts of a poly(ethylene glycol) (PEG) moiety bearing a Br and terminal azide group (Br-R1). The quaternization of P4VP with Br-R1 was performed using continuous flow chemistry and Bayesian optimization-guided reaction selection. Polymers (PyBrR1) with different degrees of functionalization were used to disperse SWCNTs and subsequently incorporated into sensors containing a platinum complex as an aerobic oxidative catalyst with a polyoxometalate (POM) redox mediator to facilitate room-temperature CH4 sensing. As the degree of quaternization in the PyBrR1-CNT composites increased, improvements in response magnitude were observed, with nominally 10% quaternized PyBrR1 giving the largest response. Incorporation of PEG improved sensor stability at relative humidities between 57-90% versus sensors fabricated from CNT dispersions with unfunctionalized P4VP. Devices fabricated with these dispersions outperformed those prepared in situ under dry conditions, and exhibited greater stability at elevated humidities. The influence of Keggin-type POM character was also evaluated to identify alternative POMs for enhanced sensor performance at high humidity. In an effort to identify areas for further improvement in algorithm performance for polymer functionalization, a kinetically informed machine learning model was explored as a route to predict reactivity of pyridine units and alkyl bromides under flow conditions.

Competitive sorption enables the emergent phenomenon of enhanced CO2-based selectivities for gas separation membranes when using microporous polymers with primary amines. However, strong secondary forces in these polymers through hydrogen bonding results in low solvent solubility, precluding standard solution processing approaches to form these polymers into membrane films. Herein, we circumvent these manufacturing constraints while maintaining competitive-sorption enhancements by synthesizing eight representative microporous poly(arylene ether)s (PAEs) with tertiary amines. High-pressure H2S, CO2, and CH4 sorption isotherms were collected for these samples to demonstrate enhanced affinity for acid gases relative to the unfunctional control polymer. Although competitive sorption was observed for all samples, improvements were less pronounced than for primary-amine-functional analogs. For H2S-based separations, the benefits of competitive sorption offset decreases in selectivity due to plasticization. This detailed study helps to elucidate the role of tertiary amines for acid gas separations in solution-processable microporous PAEs.

Perfluoroalkyl substances (PFAS), known as “forever chemicals,” are a growing concern in the sphere of human and environmental health. In response, rapid, reproducible, and inexpensive methods for PFAS detection in the environment and home water supplies are needed. We have developed a simple and inexpensive perfluoroalkyl acid detection method based on an electrically read lateral flow assay (e-LFA). Our method employs a fluorous surfactant formulation with undoped polyaniline (F-PANI) fabricated to create test lines for the lateral flow assay. In perfluoroalkyl acid sensing studies, an increase in conductivity of the F-PANI film is caused by acidification and doping of PANI. A conductivity enhancement by 10 4 -fold can be produced by this method, and we demonstrate a limit of detection for perfluorooctanoic acid (PFOA) of 400 ppt and perfluorobutanoic acid of 200 ppt. This method for PFOA detection can be expanded for wide-scale environmental and at-home water testing.

This study details the enhancement of CO2 selectivity in ring-opening metathesis polymerization (ROMP) polymers that contain nitrile moieties and micropore-generating ladder side chains. A material, CN-ROMP homopolymer, with nitriles in the ladder side chains was originally targeted and synthesized; however, its low molecular weight and backbone rigidity precluded film formation. As a result, an alternative method was pursued wherein copolymers were synthesized using norbornene (N) and nitrile norbornene (NN). Herein, we report an investigation of the structure-property relationships of backbone functionalization and grafting density on the CO2 transport properties in these ROMP polymers. Nitrile-containing copolymers showed an increase in CO2/CH4 sorption selectivity and a concomitant increase in CO2/CH4 permselectivity when compared to the unfunctionalized (nitrile-free) analogues. The stability in CO2-rich environments is enhanced as grafting density of the rigid, pore-generating side chains increases and an apparent tunability of CO2 plasticization pressure was observed as a function of norbornene content. Lower loadings of norbornene resulted in higher plasticization pressure points. Gas permeability in the ROMP copolymers was found to correlate most strongly with the concentration of the ladder macromonomers in the polymer chain.