Local Hydrogen Bond Research Articles

Per- and Polyfluoroalkyl (PFAS) Disruption of Thyroid Hormone Synthesis.

Per- and polyfluoroalkyl substances (PFAS) are a group of environmental pollutants that have been linked to a variety of health problems in humans, including the disruption of thyroid functions. Herein, for the first time, the impact of PFAS on thyroid hormone synthesis is shown. Mid- to long-chain PFAS impact thyroid hormone synthesis by changing the local hydrogen bond network as well as the required orientation of hormonogenic residues, stopping the production of thyroxine (T4). Furthermore, the toxic effects of sulfonic PFAS are more prominent than those of carboxylic PFAS, highlighting that the exposure to these specific compounds can pose greater problems for thyroid homeostasis.

Molecular biological identification of a case with A223B subtype

To study the molecular basis for a proband with A subtype B of the ABO blood group and explore the influence of amino acid variant on the activity of glycosyltransferase (GT). A proband who had presented at the First Affiliated Hospital of Zhengzhou University on July 2, 2020 was selected as the study subject. Serological identification of the ABO blood groups of the proband and her family members were performed by gel card and test tube methods. The ABO gene of the proband was identified by PCR-sequence specific primers (PCR-SSP) and DNA sequencing. A 3D molecular homologous model was constructed to predict the impact of the variant on the stability of α-(1→3)-D-N-acetylgalactosamine transferase (GTA). The red blood cells of the proband, her mother and two younger brothers showed weak agglutination with anti-A and strong agglutination with anti-B. The sera showed 1~2+ agglutination with Ac and no agglutination with Bc. Based on the serological characteristics, the proband was identified as AwB subtype. Pedigree analysis suggested that the variant was inherited from her mother. The blood group of the proband was identified as A223B type by PCR-SSP. ABO gene sequencing analysis showed that the proband has harbored heterozygous variants of c.297A>G, c.467C>T, c.526C>G, c.657C>T, c.703G>A, c.796C>A, c.803G>C, c.930G>A and c.1055insA. Based on the results of clone sequencing, it was speculated that the genotype was ABO*A223/ABO*B.01. There were c.467C>T and c.1055insA variants compared with ABO*A1.01, and c.1055insA variant compared with ABO*A1.02. Homologous modeling showed that the C-terminal of A223 GT was significantly prolonged, and the local amino acids and hydrogen bond network have changed. Above results revealed the molecular genetics mechanism of A223B subtype. The c.1055insA variant carried by the proband may affect the enzymatic activity of GTA and ultimately lead to weakening of A antigen.

Spectroscopic Evidence for Doubly Hydrogen-Bonded Cationic Dimers in the Solid, Liquid, and Gaseous Phases of Carboxyl-Functionalized Ionic Liquids.

Intermolecular interactions determine whether matter sticks together, gases condense into liquids, or liquids freeze into solids. The most prominent example is hydrogen bonding in water, responsible for the anomalous properties in the liquid phase and polymorphism in ice. The physical properties are also exceptional for ionic liquids (ILs), wherein a delicate balance of Coulomb interactions, hydrogen bonds, and dispersion interactions results in a broad liquid range and the vaporization of ILs as ion pairs. In this study, we show that strong, local, and directional hydrogen bonds govern the structures and arrangements in the solid, liquid, and gaseous phases of carboxyl-functionalized ILs. For that purpose, we explored the H-bonded motifs by X-ray diffraction and attenuated total reflection (ATR) infrared (IR) spectroscopy in the solid state, by ATR and transmission IR spectroscopy in the liquid phase, and by cryogenic ion vibrational predissociation spectroscopy (CIVPS) in the gaseous phase at low temperature. The analysis of the CO stretching bands reveals doubly hydrogen-bonded cationic dimers (c═c), resembling the archetype H-bond motif known for carboxylic acids. The like-charge doubly hydrogen-bonded ion pairs are present in the crystal structure of the IL, survive phase transition into the liquid state, and are still present in the gaseous phase even in (2,1) complexes wherein one counterion is removed and repulsive Coulomb interaction increased. The interpretation of the vibrational spectra is supported by quantum chemical methods. These observations have implications for the fundamental nature of the hydrogen bond between ions of like charge.

Functional assessment of a novel biallelic MYH3 variation causing CPSKF1B (contractures, pterygia, and spondylocarpotarsal fusion syndrome1B).

The MYH3-associated myosinopathies comprise a spectrum of rare neuromuscular disorders mainly characterized by distal arthrogryposis with or without other features like pterygia and vertebrae fusion. CPSKF1B (contractures, pterygia, and spondylocarpotarsal fusion syndrome1B) is the only known autosomal recessiveMYH3-associated myosinopathy so far, with no more than two dozen cases being reported. A boy with CPSKF1B was recruited and subjected to a comprehensive clinical and imaging evaluation. Genetic detection with whole-exome sequencing (WES) was performed on the patient and extended family members to identify the causative variation. A series of in silico and invitro investigations were carried out to verify the pathogenicity of the two variants of the identified compound heterozygous variation. The patient exhibited moderate CPSKF1B symptoms including multiarticular contractures, webbed neck, and spondylocarpotarsal fusion. WES detected a compound heterozygous MYH3 variation consisting of two variants, namely NM_002470.4: c.3377A>G; p. (E1126G) and NM_002470.4: c.5161-2A>C. It was indicated that the NM_002470.4: c.3377A>G; p. (E1126G) variant mainly impaired the local hydrogen bond formation and impacted the TGF-B pathway, while the NM_002470.4: c.5161-2A>C variant could affect the normal splicing of pre-mRNA, resulting in the appearance of multiple abnormal transcripts. The findings of this study expanded the mutation spectrum of CPSKF1B, provided an important basis for the counseling of the affected family, and also laid a foundation for the functional study of MYH3 mutations.

Salinity-mediated water self-purification via bond network distorting of H2O molecules on DRC-surface.

High salinity has plagued wastewater treatment for a long time by hindering pollutant removal, thereby becoming a global challenge for water pollution control that is difficult to overcome even with massive energy consumption. Herein, we propose a novel process for rapid salinity-mediated water self-purification in a dual-reaction-centers (DRC) system with cation-π structures. In this process, local hydrogen bond networks of H2O molecules can be distorted through the mediation of salinity, thereby opening the channels for the preferential contact of pollutants on the DRC interface. As the result, the elimination rate of pollutants increased approximately 32-fold at high salinity (100 mM) without any external energy consumption. Our findings provide a novel technology for high-efficiency and low-consumption water self-purification, which is of great significance in environmental remediation and even fine chemical industry.

Electric Double Layer Effects in Electrocatalysis: Insights from Ab Initio Simulation and Hierarchical Continuum Modeling.

Structures of the electric double layer (EDL) at electrocatalytic interfaces, which are modulated by the material properties, the electrolyte characteristics (e.g., the pH, the types and concentrations of ions), and the electrode potential, play crucial roles in the reaction kinetics. Understanding the EDL effects in electrocatalysis has attracted substantial research interest in recent years. However, the intrinsic relationships between the specific EDL structures and electrocatalytic kinetics remain poorly understood, especially on the atomic scale. In this Perspective, we briefly review the recent advances in deciphering the EDL effects mainly in hydrogen and oxygen electrocatalysis through a multiscale approach, spanning from the atomistic scale simulated by ab initio methods to the macroscale by a hierarchical approach. We highlight the importance of resolving the local reaction environment, especially the local hydrogen bond network, in understanding EDL effects. Finally, some of the remaining challenges are outlined, and an outlook for future developments in these exciting frontiers is provided.

Oscillating electric field-induced water blocking breakthrough to facilitate CO2 miscible flooding

CO2 miscible flooding is a great promising enhanced oil recovery (EOR) method. However, the loss of fracturing fluid in the formation causes water blocking that seriously impedes the realisation of CO2 miscible flooding. To solve this problem, a strategy of applying an oscillating electric field to promote CO2 breaking through water blocking and enhance the miscibility of CO2 and oil is proposed. The electric field with the frequency of 12 THz can maximise the breakthrough efficiency of water blocking, while the 16 THz electric field is most conducive to the miscibility of CO2 and oil. Under the 12 THz oscillating electric field, the prompt destruction of the local hydrogen bonds in water blocking results in the fastest breakthrough of water blocking. However, the expansion of water blocking hinders the miscibility of CO2 and oil to some extent. 16 THz oscillating electric field can induce the electric resonance of hydrogen bonds between water molecules, uniformly breaking hydrogen bonds to the greatest extent. Compared to that under the 12 THz electric field, the miscibility of CO2 and oil under the 16 THz electric field is enhanced due to the reduced expansion of water blocking.

Stabilizing α-Helicity of a Polypeptide in Aqueous Urea: Dipole Orientation or Hydrogen Bonding?

We propose a mechanism for α-helix folding of polyalanine in aqueous urea that reconciles experimental and simulation studies. Over 15 μs long, all-atom simulations reveal that, upon dehydrating the protein's first solvation shell, a delicate balance between localized urea-residue dipole interactions and hydrogen bonds dictates polypeptide solvation properties and structure. Our work clarifies the experimentally observed tendency of these alanine-rich systems to form secondary structures at low and intermediate urea concentrations. Moreover, it is consistent with the commonly accepted hydrogen-bond-induced helix unfolding, dominant at high urea concentrations. These results establish a structure-property relationship highlighting the importance of microscopic dipole-dipole orientations/interactions for the operational understanding of macroscopic protein solvation.

Inorganic Solid-State Nonlinear Optical Switch with a Linearly Tunable Tc Spanning a Wide Temperature Range.

Nonlinear optical (NLO) switch materials that turn on/off second-harmonic generation (SHG) at a phase transition temperature (Tc ) are promising for applications in the fields of photoswitching and optical computing. However, precise control of Tc remains challenging, mainly because a linearly tunable Tc has not been reported to date. Herein, we report a unique selenate, tetragonal P 21 c [Ag(NH3 )2 ]2 SeO4 with a=b=8.5569(2) Å and c=6.5208(2) Å that exhibits a strong SHG intensity (1.3×KDP) and a large birefringence (Δnobv. =0.08). This compound forms a series of isostructural solid-solution crystals [Ag(NH3 )2 ]2 Sx Se1-x O4 (x=0-1.00) that exhibit excellent NLO switching performance and an unprecedented linearly tunable spanning 430 to 356 K. The breaking of localized hydrogen bonds between SeO4 2- and the cation triggers a phase transition accompanied by hydrogen bond length changes with increasing x and a linear change in the enthalpy .

Inorganic Solid‐State Nonlinear Optical Switch with a Linearly TunableTcSpanning a Wide Temperature Range

AbstractNonlinear optical (NLO) switch materials that turn on/off second‐harmonic generation (SHG) at a phase transition temperature (Tc) are promising for applications in the fields of photoswitching and optical computing. However, precise control ofTcremains challenging, mainly because a linearly tunableTchas not been reported to date. Herein, we report a unique selenate, tetragonalP21c[Ag(NH3)2]2SeO4witha=b=8.5569(2) Å andc=6.5208(2) Å that exhibits a strong SHG intensity (1.3×KDP) and a large birefringence (Δnobv.=0.08). This compound forms a series of isostructural solid‐solution crystals [Ag(NH3)2]2SxSe1−xO4(x=0–1.00) that exhibit excellent NLO switching performance and an unprecedented linearly tunablespanning 430 to 356 K. The breaking of localized hydrogen bonds between SeO42−and the cation triggers a phase transition accompanied by hydrogen bond length changes with increasingxand a linear change in the enthalpy.

Characterizing the functional impact of embryonic myosin mutations in stem cell-derived skeletal muscle.

Divergent contractile properties of different myosins suggest that each isoform performs distinct functions in embryonic and adult skeletal muscles. To better understand the role of embryonic myosin heavy chain 3 (MYH3) in regulating skeletal muscle pattern formation, growth and regeneration, our group investigated the functional defects caused by multiple mutations. Our team generated human induced pluripotent stem cell (iPSC) lines bearing T178I or R672C mutations in MYH3. Human iPSCs bearing these mutations were differentiated into skeletal muscle and evaluated for differences in the structure, maturation and functional performance of the sarcomere. Isolated myofibril mechanics showed T178I myotubes generated significantly greater specific force compared to control myofibrils. Diseased myofibrils also expressed significantly slower rates of relaxation and prolonged thin filament deactivation compared to controls. Myofibril preparations were also used to compare ATP binding rates and showed homozygous R672C myofibrils have faster ATP binding rates compared to heterozygous and control preparations. When incorporated into 3D engineered tissues, these changes in MYH3 mechanics resulted in slower relaxation kinetics and an incomplete relaxation of the tissue in response to repetitive tetanic stimulation, which may explain the emergence of developmental contractures in patients possessing MYH3 mutations. Molecular dynamics simulations of R672C and T178I mutations in the post rigor state showed greater separation between the β-sheet and SH-Helix than in controls. Mutations also disrupted local salt bridges and hydrogen bond formation in some residues that help stabilize the nucleotide binding pocket and converter-connected helix. Interrupted structural communication between the nucleotide binding pocket and surrounding functional regions may underly the impaired relaxation phenotype. Ongoing studies will further characterize the effect of mutation on actin-myosin binding, crossbridge cycling kinetics, the maturation of skeletal myotubes over time, and myosin isoform switching dynamics.

Embryonic myosin mutations alter the mechanics and maturation of HiPSC derived skeletal muscle.

Distal arthrogryposis (DA) is a skeletal muscle disorder characterized by joint contractures predominantly localized in the distal extremities. DA associated syndromes like Freeman-Sheldon syndrome (FSS) are linked to mutations in the MYH3 gene that encodes the embryonic skeletal muscle myosin. To study the mutation and its effect on developing muscle, we generated human induced pluripotent stem cell (hiPSC) lines bearing T178I or R672C MYH3 mutations. hiPSC were differentiated into skeletal muscle and evaluated for differences in the maturation of the contractile unit and its functional performance. Preliminary myofibril mechanics measurements showed T178I myotubes generated significantly greater specific force compared to control myofibrils. Diseased myofibrils also expressed significantly slower rates of relaxation and prolonged thin filament deactivation compared to control myofibrils. Myofibril preparations were also used to compare ATP binding rates across conditions. Preliminary results showed homozygous R672C myofibrils have faster ATP binding rates compared to heterozygous and control preparations. Mutations in MYH3 were also associated with alterations in myosin isoform content, with homozygous R672C having reduced MYH3 levels in day 7 cells. Molecular dynamics simulations of R672C and T178I mutations in the post rigor state showed greater separation between the beta-sheet and SH-helix than in controls. Mutation also disrupted local salt bridges and hydrogen bond formation in some residues that help stabilize the nucleotide binding pocket and converter-connected helix. Interrupted structural communication between the nucleotide binding pocket and surrounding functional regions may underly the impaired relaxation phenotype. Ongoing studies will further characterize the effect of mutation on actin-myosin binding, crossbridge cycling kinetics, the maturation of skeletal myotubes over time, and myosin isoform switching dynamics.

Vibrational dynamics of liquid water in an external electric field.

In our present study, we have investigated the effects of an externally applied static electric field on the vibrational dynamics of liquid water (D2O) using ab initio molecular dynamics. The rate of vibrational spectral diffusion is obtained from simulated two-dimensional infrared spectra, three-pulse photon echo intensity, and frequency correlation functions and distributions. We find that the static vibrational frequency distribution undergoes a redshift of 90 cm-1 whereas the overall vibrational dynamics get slower with the relaxation time constant to be around 4.9 ps. Thus we infer that the local hydrogen bond network tends to reorganize in the presence of an external field with an increase in local structural order as evident from the overall slower vibrational dynamics and reduced molar entropy.

Thermochemical Study of CH3NH3Pb(Cl1-xBrx)3 Solid Solutions.

Hybrid organic-inorganic perovskite halides, and, in particular, their mixed halide solid solutions, belong to a broad class of materials which appear promising for a wide range of potential applications in various optoelectronic devices. However, these materials are notorious for their stability issues, including their sensitivity to atmospheric oxygen and moisture as well as phase separation under illumination. The thermodynamic properties, such as enthalpy, entropy, and Gibbs free energy of mixing, of perovskite halide solid solutions are strongly required to shed some light on their stability. Herein, we report the results of an experimental thermochemical study of the CH3NH3Pb(Cl1-xBrx)3 mixed halides by solution calorimetry. Combining these results with molecular dynamics simulation revealed the complex and irregular shape of the compositional dependence of the mixing enthalpy to be the result of a complex interplay between the local lattice strain, hydrogen bonds, and energetics of these solid solutions.

Local Weak Hydrogen Bonds Significantly Enhance CO 2 Electroreduction Performances of a Metal–Organic Framework

Local Weak Hydrogen Bonds Significantly Enhance CO ₂ Electroreduction Performances of a Metal–Organic Framework

Ionic Dynamics and Vibrational Spectral Diffusion of a Protic Alkylammonium Ionic Salt through Intrinsic Cationic N-H Vibrational Probe from FPMD Simulations.

We employed density functional theory (DFT)-based molecular dynamics simulations to explore the structure, dynamics, and spectral properties of the protic ionic entity trimethylammonium chloride (TMACl). Structural investigations include calculating the site-site radial distribution functions (RDFs), the distribution of constituent cations and anions in three-dimensional space, and combined distribution functions of the hydrogen-bonded pair RDF versus angle, revealing the structural characteristics of the ionic solvation and the intermolecular interactions within ions. Further, we determined the instantaneous vibrational stretching frequencies of the intrinsic N-H stretch probe modes by applying the time-series wavelet method. The associated ionic dynamics within the protic ionic compound were investigated by calculating the time-evolution of the fluctuating frequencies and the frequency-time correlation functions (FFCFs). The time scale related to the local structural relaxation process and the average hydrogen bond lifetime, ion cage dynamics, and mean squared displacement were investigated. The faster decay component of the FFCFs, depicting the intermolecular motion of intact hydrogen bonds in TMACl, is 0.07 ps for the Perdew-Burke-Ernzerhof (PBE)-based simulation and 0.06 ps for the PBE-D2 representation. The slower time scale of the longer picosecond decay time component of PBE and PBE-D2 representations are 3.13 and 2.87 ps, respectively. These picosecond time scales represent more significant fluctuations of the hydrogen-bonding partners in the ionic entity and hydrogen-bond jump events accompanied by large angular jumps. The longest picosecond time scales represent structural relaxation, including large angular jumps and ion-pair dynamics. Also, ion cage lifetimes correlate with the slowest time scale of the associated dynamics of vibrational spectral diffusion despite the type of DFT functional. This study benchmarks DFT treatments of the exchange-correlation functional with and without the van der Waals (vdW) dispersion correction scheme. The inclusion of vdW interactions to the PBE functional represents a less structured state of the ionic entity and faster dynamics of the molecular motions relative to the one predicted by the PBE system. All the results illustrate the necessity of accurately describing the Coulomb interactions, vdW dispersive interactive forces, and localized hydrogen bonds required to sustain the energetic balance in this ionic salt.

Engineering a Local Free Water Enriched Microenvironment for Surpassing Platinum Hydrogen Evolution Activity.

Manipulating the catalyst-electrolyte interface to push reactants into the inner Helmholtz plane (IHP) is highly desirable for efficient electrocatalysts, however, it has rarely been implemented due to the elusive electrochemical IHP and inherent inert catalyst surface. Here, we propose the introduction of local force fields by the surface hydroxyl group to engineer the electrochemical microenvironment and enhance alkaline hydrogen evolution activity. Taking a hydroxyl group immobilized Ni/Ni3 C heterostructure as a prototype, we reveal that the local hydrogen bond induced by the surface hydroxyl group drags 4-coordinated hydrogen-bonded H2 O molecules across the IHP to become free H2 O and thus continuously supply reactants forcatalytic sites catalytic sites. In addition, the hydroxyl group coupled with the Ni/Ni3 C heterostructure further lowers the water dissociation energy by polarization effects. As a direct outcome, hydroxyl-rich catalysts surpass Pt/C activity at high current density (500 mA cm-2 @ ≈276 mV) in alkaline medium.

Engineering a Local Free Water Enriched Microenvironment for Surpassing Platinum Hydrogen Evolution Activity

AbstractManipulating the catalyst–electrolyte interface to push reactants into the inner Helmholtz plane (IHP) is highly desirable for efficient electrocatalysts, however, it has rarely been implemented due to the elusive electrochemical IHP and inherent inert catalyst surface. Here, we propose the introduction of local force fields by the surface hydroxyl group to engineer the electrochemical microenvironment and enhance alkaline hydrogen evolution activity. Taking a hydroxyl group immobilized Ni/Ni3C heterostructure as a prototype, we reveal that the local hydrogen bond induced by the surface hydroxyl group drags 4‐coordinated hydrogen‐bonded H2O molecules across the IHP to become free H2O and thus continuously supply reactants forcatalytic sites catalytic sites. In addition, the hydroxyl group coupled with the Ni/Ni3C heterostructure further lowers the water dissociation energy by polarization effects. As a direct outcome, hydroxyl‐rich catalysts surpass Pt/C activity at high current density (500 mA cm−2@ ≈276 mV) in alkaline medium.

Selectively Altering the Reactivity of Transient Organic Radical Ions via Their Solvation Environment.

Photoexcitation of the charge transfer band of electron donor-acceptor complexes composed of toluene and 1,2,4,5-tetracyanobenzene yields organic radical ion pairs whose ultrafast reactive dynamics are determined by equilibrium solvent properties. A comparative study of ultrafast reaction rates in a series of alkane alcohols identified their dependence on the local polarizability and hydrogen bond donating/accepting character of the solvent. Because of the rapid and efficient equilibration of these radical ion pairs into solvent-separated species, simple modifications to bulk conditions can be used as a means to selectively alter their decay rates. Selectively altering distinct stages in this photochemical cycle via cosolutes or additives is a valuable step toward understanding and controlling the reactivity of organic radical ions in complex environments.

Molecular insight in the wetting behavior of nanoscale water droplet on CSH surface: Effects of Ca/Si ratio

The distribution state and wettability of water molecules on the Calcium silicate hydrate (CSH) surface closely affect the transport behavior of water on CSH gel pores, thus affecting the durability of concrete. To understand the wetting behavior of water droplets on the CSH gel interface with different Ca/Si ratios, this paper focuses on the local structure, ionic pairs, hydrogen bonds, orientation characteristics and dynamic properties of water molecules on the CSH interface based on molecular dynamics simulation. At the molecular level, the water droplets have a larger contact angle at the CSH surface with a low Ca/Si ratio because the CSH with a low Ca/Si ratio has a dense structure and makes it difficult for water molecules to penetrate the silicate chain. Analysis reveals that the dense silicate chains tend to absorb and restrict water molecules in the form of static electricity. The orientation distribution of water molecules at different positions on the CSH interface reveals the driving force of wetting behavior. The results of dynamic properties analysis show that CSH with a high Ca/Si ratio has better wettability to water droplets.