Nanoconfinement of Carbon Dioxide within Interfacial Aqueous/Ionic Liquid Systems.

Nanoporous, gas-selective membranes have shown encouraging results for the removal of CO from flue gas, yet the optimal design for such membranes is often unknown. Therefore, we used molecular dynamics simulations to elucidate the behavior of CO within aqueous and ionic liquid (IL) systems ([EMIM][TFSI] and [OMIM][TFSI]), both confined individually and as an interfacial aqueous/IL system. We found that within aqueous systems the mobility of CO is reduced due to interactions between the CO oxygens and hydroxyl groups on the pore surface.

Erratum: Addition to "Carbonic Anhydrase Robustness for Use in Nanoscale CO Capture Technologies".

[This corrects the article DOI: 10.1021/acsomega.3c02630.

Capturing CO in Quadrupolar Binding Pockets: Broadband Microwave Spectroscopy of Pyrimidine-(CO), = 1,2.

Pyrimidine has two in-plane CH(δ+)/(δ-)/CH(δ+) binding sites that are complementary to the (δ-/2δ+/δ-) quadrupole moment of CO. We recorded broadband microwave spectra over the 7.5-17.

Transport and Energetics of Carbon Dioxide in Ionic Liquids at Aqueous Interfaces.

A major hurdle in utilizing carbon dioxide (CO) lies in separating it from industrial flue gas mixtures and finding suitable storage methods that enable its application in various industries. To address this issue, we utilized a combination of molecular dynamics simulations and experiments to investigate the behavior of CO in common room-temperature ionic liquids (RTIL) when in contact with aqueous interfaces. Our investigation of RTILs, [EMIM][TFSI] and [OMIM][TFSI], and their interaction with a pure water layer mimics the environment of a previously developed ultrathin enzymatic liquid membrane for CO separation.

Energetics of high temperature degradation of fentanyl into primary and secondary products.

Fentanyl is a synthetic opioid used for managing chronic pain. Due to its higher potency (50-100×) than morphine, fentanyl is also an abused drug. A sensor that could detect illicit fentanyl by identifying its thermally degraded fragments would be helpful to law enforcement.

Binding of Li to Negatively Charged and Neutral Ligands in Polymer Electrolytes.

Conceptually, single-ion polymer electrolytes (SIPE) with the anion bound to the polymer could solve major issues in Li-ion batteries, but their conductivity is too low. Experimentally, weakly interacting anionic groups have the best conductivity. To provide a theoretical basis for this result, density functional theory calculations of the optimized geometries and energies are performed for charged ligands used in SIPE.

Binding of carboxylate and water to monovalent cations.

The interactions of carboxylate anions with water and cations are important for a wide variety of systems, both biological and synthetic. To gain insight on properties of the local complexes, we apply density functional theory, to treat the complex electrostatic interactions, and investigate mixtures with varied numbers of carboxylate anions (acetate) and waters binding to monovalent cations, Li, Na and K. The optimal structure with overall lowest free energy contains two acetates and two waters such that the cation is four-fold coordinated, similar to structures found earlier for pure water or pure carboxylate ligands.

Carbonic Anhydrase Robustness for Use in Nanoscale CO Capture Technologies.

Continued dependence on crude oil and natural gas resources for fossil fuels has caused global atmospheric carbon dioxide (CO) emissions to increase to record-setting proportions. There is an urgent need for efficient and inexpensive carbon sequestration systems to mitigate large-scale emissions of CO from industrial flue gas. Carbonic anhydrase (CA) has shown high potential for enhanced CO capture applications compared to conventional absorption-based methods currently utilized in various industrial settings.

Insight into the K channel's selectivity from binding of K, Na and water to -methylacetamide.

In potassium channels that conduct K selectively over Na, which sites are occupied by K or water and the mechanism of selectivity are unresolved questions. The combination of the energetics and the constraints imposed by the protein structure yield the selective permeation and occupancy. To gain insight into the combination of structure and energetics, we performed density functional theory (DFT) calculations of multiple -methyl acetamide (NMA) ligands binding to K and Na, relative to hydrated K and Na.

Molecular Cage Reports on Its Contents: Spectroscopic Signatures of Cryo-Cooled K- and Ba-Benzocryptand Complexes.

UV photofragment spectroscopy and IR-UV double resonance methods are used to determine the structure and spectroscopic responses of a three-dimensional [2.2.2]-benzocryptand cage to the incorporation of a single K or Ba imbedded inside it (labeled as K-BzCrypt, Ba-BzCrypt).

Control of the Structural Charge Distribution and Hydration State upon Intercalation of CO into Expansive Clay Interlayers.

Numerous experimental investigations indicated that expansive clays such as montmorillonite can intercalate CO preferentially into their interlayers and therefore potentially act as a material for CO separation, capture, and storage. However, an understanding of the energy-structure relationship during the intercalation of CO into clay interlayers remains elusive. Here, we use metadynamics molecular dynamics simulations to elucidate the energy landscape associated with CO intercalation.

Hydrophobic Nanoconfinement Enhances CO Conversion to HCO.

Understanding the formation of HCO in water from CO is important in environmental and industrial processes. Although numerous investigations have studied this reaction, the conversion of CO to HCO in nanopores, and how it differs from that in bulk water, has not been understood. We use ReaxFF metadynamics molecular simulations to demonstrate striking differences in the free energy of CO conversion to HCO in bulk and nanoconfined aqueous environments.

Development of AMOEBA Polarizable Force Field for Rare-Earth La Interaction with Bioinspired Ligands.

Rare-earth metals (REMs) are crucial for many important industries, such as power generation and storage, in addition to cancer treatment and medical imaging. One promising new REM refinement approach involves mimicking the highly selective and efficient binding of REMs observed in relatively recently discovered proteins. However, realizing any such bioinspired approach requires an understanding of the biological recognition mechanisms.

Carboxylate binding prefers two cations to one.

Almost all studies of specific ion binding by carboxylates (-COO) have considered only a single cation, but clustering of ions and ligands is a common phenomenon. We apply density functional theory to investigate how variations in the number of acetate ligands in binding to two monovalent cations affects ion binding preferences. We study a series of monovalent (Li, Na, K, Cs) ions relevant to experimental work on many topics, including ion channels, battery storage, water purification and solar cells.

Hydrated Anions: From Clusters to Bulk Solution with Quasi-Chemical Theory.

The interactions of hydrated ions with molecular and macromolecular solution and interface partners are strong on a chemical energy scale. Here, we recount the foremost ab initio theory for the evaluation of the hydration free energies of ions, namely, quasi-chemical theory (QCT). We focus on anions, particularly halides but also the hydroxide anion, because they have been outstanding challenges for all theories.

Trapping Ca inside a molecular cavity: computational study of the potential energy surfaces for Ca-[]cycloparaphenylene, = 5-12.

Ion trap quantum computing utilizes electronic states of atomic ions such as Ca to encode information on to a qubit. To explore the fundamental properties of Ca inside molecular cavities, we describe here a computational study of Ca bound inside neutral []-cycloparaphenylenes ( = 5-12), often referred to as "nanohoops". This study characterizes optimized structures, harmonic vibrational frequencies, potential energy surfaces, and ion molecular orbital distortion as functions of increasing nanohoop size.

Enhancing Paraoxon Binding to Organophosphorus Hydrolase Active Site.

Organophosphorus hydrolase (OPH) is a metalloenzyme that can hydrolyze organophosphorus agents resulting in products that are generally of reduced toxicity. The best OPH substrate found to date is diethyl p-nitrophenyl phosphate (paraoxon). Most structural and kinetic studies assume that the binding orientation of paraoxon is identical to that of diethyl 4-methylbenzylphosphonate, which is the only substrate analog co-crystallized with OPH.

Quantum Calculations of VX Ammonolysis and Hydrolysis Pathways via Hydrated Lithium Nitride.

Recently, lithium nitride (LiN) has been proposed as a chemical warfare agent (CWA) neutralization reagent for its ability to produce nucleophilic ammonia molecules and hydroxide ions in aqueous solution. Quantum chemical calculations can provide insight into the LiN neutralization process that has been studied experimentally. Here, we calculate reaction-free energies associated with the LiN-based neutralization of the CWA VX using quantum chemical density functional theory and ab initio methods.

Thermodynamics of ion binding and occupancy in potassium channels.

Potassium channels modulate various cellular functions through efficient and selective conduction of K ions. The mechanism of ion conduction in potassium channels has recently emerged as a topic of debate. Crystal structures of potassium channels show four K ions bound to adjacent binding sites in the selectivity filter, while chemical intuition and molecular modeling suggest that the direct ion contacts are unstable.