of antifouling materials are more commonly focused on the fouling of fully submerged substrates. [9] Accordingly, less is known about specific design principles that operate well at the triple interface beyond what is already known about the solid-liquid interface. Despite their exceptional antifouling performance in submerged applications ranging from medical device coatings to reverse osmosis membranes, [10,11] zwitterionic polymers incur considerable growth of P. aeruginosa biofilm at the three-phase contact line. The simultaneous need for a hydrophobic surface in air and a hydrophilic surface in water calls for a dynamic interface design that can switch between the two surface energy states in response to the environment. [12] Molecular-scale heterogeneities of amphiphilic polymer coatings were enabled by the initiated chemical vapor deposition (iCVD) technique. The heterogeneities composed of zwitterionic and fluorinated moieties were shown to effectively reduce biofilm formation at the solid-liquid-air interface. To date, antifouling polymer chemistries aimed at the solid-liquid interface have relied predominantly on strong surface hydration, creating a large enthalpic penalty for microbes to replace tightly bound water molecules. The most prevalent antifouling polymer continues to be poly(ethylene glycol) and its derivatives, which feature a large fraction of hydrophilic ether bonds along the polymer backbone. [13] In the past decade, zwitterionic polymers have emerged as a promising alternative because of the strong electrostatic hydration resulting from zwitterionic moieties such as phosphorylcholine, carboxybetaine, or sulfobetaine. [14,15] Impressively, over 92% reduction in adhesion of Escherichia coli and Staphylococcus aureus has been achieved over 3 h using a zwitterionic 2-methacryloyloxyethyl phosphorylcholine coating; up to 99% reduction in adhesion of E. coli was observed after 2 h on 2-methacryloyl phosphorylcholine gels. [16,17] With nearzero water contact angles, zwitterionic polymers have pushed the performance of hydration-based antifouling materials close to the thermodynamic limit. Amphiphilic polymers have become a major focus of antifouling materials research in recent years in an attempt to build upon the successes of zwitterionic polymers. [18] The antifouling effect of amphiphilic polymers has been attributed to the unwelcoming landscape featuring domains of heterogeneous surface Biofouling at the solid-liquid-air interface poses a serious threat to public health and environmental sustainability. Despite the variety of antifouling materials developed, few have proven to resist fouling at the three-phase contact line. In fact, antifouling at the liquid-solid interface and the air-solid interface call for opposite surface properties-hydrophilic for the former and hydrophobic for the latter. By devising a new design strategy, one that maximizes the mismatch of surface energies of comonomers for dynamic chain reorientation at the three-phase contact line, an antifouling amphiphilic copo...

We report the synthesis, characterization, and catalytic CO2 reduction activity of two LMn­(CO)3Br complexes with carbene-pyridine-carbene pincer ligands, [MnCNCMe]Br 1 and [MnCNCBn]Br (Bn = benzyl) 2. X-ray crystallography reveals an octahedral coordination environment with an outer sphere Br anion for 1. Catalyst 2 performs the reduction of CO2 to CO at 100 mV more positive potential with similar current densities as 1. We hypothesize the bulkier benzyl arms on the pincer hinder formation of a dimer. They also alter the wingtip electronics, enabling operation at a lower overpotential. We use normal pulse voltammetry and diffusion ordered spectroscopy to quantify a 1e– reduction per manganese center at the catalytic onset. We now show turnover even in the absence of added protons..

Reduced biofilm formation is highly desirable in applications ranging from transportation to separations and healthcare. Biofilms often form at the three-phase interface where air, liquid, and solid coexist due to the close proximity to nutrients and oxygen. Reducing biofilm formation at the triple interface presents challenges because of the conflicting requirements for hydrophobicity at the air−solid interface (for selfcleaning properties) and for hydrophilicity at the liquid−solid interface (for reduced foulant adhesion). Meeting those needs simultaneously likely entails a dynamic surface, capable of shifting the surface energy landscape in response to wetting conditions and thus enabling hydrophobicity in air and hydrophilicity in water.Here, we designed a facile approach to render existing surfaces resistant to biofilm formation at the triple interface. By adding trace amounts (∼0.1 mM) of surfactants, biofilm formation of Pseudomonas aeruginosa (known to form biofilm at the triple interface) was reduced on all surfaces tested, ranging from hydrophilic to hydrophobic, polar to nonpolar. That reduced fouling was not a result of the known antimicrobial effects. Instead, it was attributed to the surface-adsorbed surfactants that dynamically control surface energy at the triple interface. To further understand the effect of surfactant−surface interactions on biofilm reduction, we systematically varied the surfactant charge type and surface properties (surface energy and charge). Electrostatic interactions between surfactants and surfaces were identified as an influential factor when predicting the relative fouling reduction upon introduction of surfactants. Nevertheless, biofilm formation was reduced even on the charge-neutral, fluorinated surface made of poly(1H, 1H, 2H, 2H-perfluorodecyl acrylate) by more than 2-fold simply via adding 0.2 mM dodecyl trimethylammonium chloride or 0.3 mM sodium dodecyl sulfate. Given its robustness, this strategy is broadly applicable for reducing fouling on existing surfaces, which in turn improves the cost-effectiveness of membrane separations and mitigates contaminations and nosocomial infections in healthcare.

Electroanalytical methods have become central tools for the development of molecular redox chemistry in the context of energy sciences and synthetic methods. Cyclic voltammetry (CV) is a routine diagnostic method for the measurement of the equilibrium potential of a redox couple. When electrochemical processes are reversible, CV may be used to determine the number of electrons involved in the redox transition. However, on the timescale of the measurement, redox couples can appear distorted due to short lifetimes of ion radicals or coupled chemical processes. In these cases, the number of electrons involved in a redox process is unclear when following the most commonly available methods. With the advent of a renaissance in electrochemistry‐based synthetic methods, we report a method based on combination of techniques: Normal Pulse Voltammetry (NPV) and a routine NMR experiment: Diffusion Ordered Spectroscopy (DOSY) to enable the determination of the number of electrons, n for a redox transition of such a couple. These two measurements provide an expeditious way to determine n using commonly available equipment.

At the biointerface where materials and microorganisms meet, the organic and synthetic worlds merge into a new science that directs the design and safe use of synthetic materials for biological applications. Vapor deposition techniques provide an effective way to control the material properties of these biointerfaces with molecular-level precision that is important for biomaterials to interface with bacteria. In recent years, biointerface research that focuses on bacteria–surface interactions has been primarily driven by the goals of killing bacteria (antimicrobial) and fouling prevention (antifouling). Nevertheless, vapor deposition techniques have the potential to create biointerfaces with features that can manipulate and dictate the behavior of bacteria rather than killing or deterring them. In this review, we focus on recent advances in antimicrobial and antifouling biointerfaces produced through vapor deposition and provide an outlook on opportunities to capitalize on the features of these techniques to find unexplored connections between surface features and microbial behavior.