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The notion of asymmetrical Hydrogen Bond (O:H-O) Cooperativity and Polarizability (HBCP) has enabled exploration of the core physics behind irregularities of water and ice, particularly, the evolution of mass density, phase stability, energy exchange, and their transition velocity under perturbation. We humbly share the initiatives of the quasisolidity presented between Liquid and Ice, the supersolidity pertained to polarization by electrification or molecular undercoordination, and the H ↔ H and O: ⇔ :O repulsivity owing to the respective injection of excessive protons and lone pairs to the liquid by solvation. The O—O repulsivity forms the key that drives the O:H-O bond to cooperatively relax its segmental length, cohesive energy, vibration frequency, and specific heat upon perturbation, which establishes an efficient set of parameters to feature the bonding and electronic dynamics in the frequency–space–time domains. An interplay of the segmental specific heats defines the mass densities, phase boundaries, and the exotic quasisolid (QS) phase that exhibits negative thermal expansivity through H-O contracting less than the scale of O:H expansion upon cooling. However, the H-O bond undergoes cooling elongation in the Liquid and the Ice-I phase and remains silent in the XI phase. H-O bond absorbs energy by contraction and does it inverse at expansion. The O:H nonbond always relaxes more than the H-O bond does in contrasting direction. Mechanical compression symmetrizes the O:H-O segmental length associated with polarization, which disperses inwardly the QS phase boundary to lower the T m for melting but raise the temperature T N for ice nucleation and the T V for evaporation, resulting in the phenomena of ice regelation and instant-ice formation. Polarization, however, has the contrast effect to compression on the hydrogen bond relaxation and phase transition. The polarization converts the pristine water into the gel-like, hydrophobic, and viscoelastic supersolid which is less-dense and thermally more diffusive and stable, entitling surface premelting, superheating at T m , and supercooling at T N and T V. Polarization enhances the dielectrics of water and widens the bandgap of ice. The supersolidity ensures the 120 K superelasticity of ice microfibers and the 330 K stability of the electrified water bridge crossing the rims of infilled containers. The high elasticity of the softer O:H nonbond and the interface electrostatic repulsivity secure the slipperiness of ice and the superfluidity of water traveling in fine channels. The skin supersolidity and the O:H-O bond memorability uniquely foster the Mpemba effect — warm water cools more quickly. The H ↔ H or O: ⇔ :O repulsivity modifies the bonding network and solution properties through solvent H-O bond elongation, solute H-O bond contraction, and polarization. The HBCP premise has thus correlated the irregularity of water and ice to the O:H-O bonding and electronic dynamics under perturbation. Further extension of the HBCP to aqueous and molecular assemblies involved with electron lone pairs and coupling interactions could be even more fascinating and profoundly promising. [Display omitted] • O—O repulsive coupling interaction entitles the irregularity of water and ice. • O:H-O bond cooperativity and polarizability revolutionizes the parameter space. • Perturbations drive the quasisolidity, supersolidity, H ↔ H and O: ⇔ :O repulsivity. • Specific-heat disparity resolves water's density anomalies and phase boundaries. • The T m and T N /T V vary respectively with the H-O and the O:H binding energy. • (e; ± ;H 3 O + ;HO −) ⋅ 4H 2 O:6H 2 O hydration revises solution's network and properties. [ABSTRACT FROM AUTHOR]

We systematically examined the effect of (H, Li)Cl and LiOH solvation on the O:H O bond network deformation, surface tension (contact angle), solution electrical conductivity, thermomics, and viscosity evolution aiming to clarifying the functionalities for ions, lone pairs, and protons acting in these solutions. Results confirmed that H+ and electron lone pair ':' introduction turns out the (H 3 O+, OH−)·4H 2 O motifs and that the Li+ and Cl− form each a hydration volume through the screened electrostatic polarization. The (H 3 O+, OH−)·4H 2 O turns an O:H O bond into the H ↔ H anti–HB that disrupts the HCl solution network and its surface tension and into the O:⇔:O super–HB compressor that raises the LiOH solution surface tension and viscosity, as well as the solution temperature during solvation. The Li+/Cl− ion reserves/reduces its hydration volume because of the complete/incomplete screen shielding by the ordered hydrating H 2 O dipoles and the Cl− ↔ Cl− repulsion at higher concentrations. The invariant/variant Li+/Cl− hydration volume dictates, respectively, the linear/nonlinear concentration dependence of the Jones–Dole viscosity. Except for the HCl/H 2 O surface tension and LiOH/H 2 O viscosity, the conductivity, surface tension, and viscosity of these solutions follow the Jones–Dole notion that underscores the faction of bond transition from the mode of water to hydration. Proton H+, lone pair ':', Li+ and Cl− injection mediates cooperatively the HB network, conductivity, surface tension, and viscosity of (H, Li)Cl and LiOH solutions through H ↔ H fragilization, O:⇔:O compression, ionic screened polarization, Cl− ↔ Cl− repulsion, solvent H O bond elongation, and undercoordinated solute H O bond contraction. Unlabelled Image • Proton H+, lone pair ':', Li+ and Cl− hydration distort the (H, Li)Cl and LiOH solution network. • H ↔ H fragilization, O:⇔:O compression, ionic screened polarization, Cl− ↔ Cl− repulsion coexist. • Polarization and inter-solute repulsion determine the solution properties. • H O bond relaxation exchanges energy to the exo- and endothermic hydration. [ABSTRACT FROM AUTHOR]

The structural symmetry and molecular separation in water and ice remain uncertain. We present herewith a solution to unifying the density, the structure order and symmetry, the size (H-O length dH), and the separation (dOO = dL + dH or the O:H length dH) of molecules packing in water and ice in terms of statistic mean. This solution reconciles: i) the dL, and the dH symmetrization of the O:H-O bond in compressed ice, ii) the dOO relaxation of cooling water and ice and, iii) the dOO expansion of a dimer and between molecules at water surface. With any one of the dOO, the density r(g.cm-3), the dL, and the dH, as a known input, one can resolve the rest quantities using this solution that is probing conditions or methods independent. We clarified that: i) liquid water prefers statistically the mono-phase of tetrahedrally-coordinated structure with fluctuation, ii) the low-density phase (supersolid phase as it is strongly polarized with even lower density) exists only in regions consisting molecules with fewer than four neighbors and, iii) repulsion between electron pairs on adjacent oxygen atoms dictates the cooperative relaxation of the segmented O:H-O bond, which is responsible for the performance of water and ice. [ABSTRACT FROM AUTHOR]

Understanding the stabilization of nitrogen heterocycles is critical in the field of energetic materials and calls for innovative knowledge of nitrogen aromatics. Herewith, we report for the first time that nitrogen lone pair electron (NLPE) delocalization in five-membered nitrogen heterocycles creates a second σ-aromaticity in addition to the prototypical π-aromaticity. The NLPE delocalization and the attendant dual-aromaticity are enhanced as more carbon atoms in the ring are substituted by unsaturated nitrogen atoms. The presence of adjacent nitrogen atoms in the ring can enhance the aromaticity of the nitrogen heterocycles and improve in-crystal intermolecular binding strength but will decrease the firmness of the individual molecular architecture. Notably, such σ-aromaticity is not present in six-membered nitrogen heterocycles, probably due to the longer bonds and broader regions of their rings; therefore, six-membered heterocycles present overall lower aromaticity than five-membered heterocycles. This work brings new knowledge to nitrogen aromatics and is expected to inspire broad interest in the chemistry community. [ABSTRACT FROM AUTHOR]

Energy density and structure stability are of key concerns in devising energy materials such as CNHO molecular crystals and the emerging cyclo-N 5 − complexes for desired explosive functionalities with a mechanism being open for exploration. An extension of the recent progress in solvation suggests that a combination of the intermolecular hydrogen bond (X:H–Y or HB with ':' being electron lone pair of X, Y = O or N) tension and the super-HB (X:⇔:Y) or anti-HB (H↔H) compression not only stabilizes the structure but also stores excessive energy by shortening the intramolecular bonds. The presence of the X:H constrains and the presence of the X:⇔:Y and/or H↔H fosters the explosion. Observations suggest that the absence of X:H–Y tension results in the spontaneous aquatic explosion of alkali metals and molten alkali halides. The lack of X:⇔:Y repulsion fosters no explosion of the molten NaCl in liquid NH 3 , nor the molten Na 2 CO 3 salt or H 3 BO 3 acid in water. The findings shall offer guidelines for devising efficient energy materials and reconciling the nature origin of water ice, aqueous solutions, and explosive energy materials – significance of electron lone pairs and protons. The combination of the hydrogen-bond (X:H–Y) tension and the super-HB (X:⇔:Y) or the anti-HB (H↔H) repulsion not only stabilizes the structure but also stores energy by shortening the intramolecular covalent bonds. The X:H tension constrains and the X:⇔:Y repulsion fosters explosion. Unlabelled Image • Segmental cooperativity of the X:H-Y oscillator pair dictates the behavior of aqueous solutions. • Excessive H+ or lone pairs ":" derive H↔H or X:⇔:Y repulsion in molecular crystals/liquids. • X:⇔:Y or/and H↔H repulsion and X:H-Y tension governs the stability and energy of crystals. • The absence/presence of the X:H-Y tension fosters the spontaneous/constrained explosion. [ABSTRACT FROM AUTHOR]

Perturbation Raman spectroscopy has underscored the hydrogen bond (O:H–O or HB) cooperativity and polarizability (HBCP) for water, which offers a proper parameter space for the performance of the HB and electrons in the energy-space-time domains. The O O repulsive coupling drives the O:H–O segmental length and energy to relax cooperatively upon perturbation. Mechanical compression shortens and stiffens the O:H nonbond while lengthens and softens the H O bond associated with polarization. However, electrification by an electric field or charge injection, or molecular undercoordination at a surface, relaxes the O:H–O in a contrasting way to the compression with derivation of the supersolid phase that is viscoelastic, less dense, thermally diffusive, and mechanically and thermally more stable. The H O bond exhibits negative thermal expansivity in the liquid and the ice-I phase while its length responds in proportional to temperature in the quasisolid phase. The O:H–O relaxation modifies the mass densities, phase boundaries, critical temperatures and the polarization endows the slipperiness of ice and superfluidity of water at the nanometer scale. Protons injection by acid solvation creates the H↔H anti-HB and introduction of electron lone pairs derives the O:⇔:O super-HB into the solutions of base or H 2 O 2 hydrogen-peroxide. The repulsive H↔H and O:⇔:O interactions lengthen the solvent H O bond while the solute H O bond contracts because its bond order loss. Differential phonon spectroscopy quantifies the abundance, structure order, and stiffness of the bonds transiting from the mode of pristine water to the perturbed states. The HBCP and the perturbative spectroscopy have enabled the dynamic potentials for the relaxing O:H–O bond. Findings not only amplified the power of the Raman spectroscopy but also substantiated the understanding of anomalies of water subjecting to perturbation. Scaling relations for the HBCP of the (a) measured segmental length and the (b) computed H O vibration frequency. [Display omitted] • O O repulsion couples the intramolecular H O and intermolecular O:H interactions. • O:H–O segmental length, energy, frequency, and specific heat parameterize water ice. • Mechanical compression shortens the O:H and lengthens the H O and polarizes water. • Electrification or molecular undercoordination effects contrastingly to compression. • DPS distills the abundance-order-stiffness transition of O:H–O driven by perturbation. [ABSTRACT FROM AUTHOR]

The H N bond in the TATB assembly exhibits excitingly negative compressibility and negative thermal expansivity because of the unprecedented O N coupling interactions. [Display omitted] • O:H N bond in TATB acts the same to O:H O in H 2 O upon compression and heating. • H N bond possesses negative compressibility and negative thermal expansibility. • Heating shortens C NH 2 and N H but does the C NO 2 and N O contrastingly. • The O/N:H nonbonds possess the regular compressibility and thermal expansivity. • The N O repulsion drives the unusual response of the O:H N bond to perturbation. Incorporating the mechanical and thermal perturbations to the Raman spectroscopy has enabled resolution to the response of the individually segmented C N 2H:2O N C interactions for the 1,3,5-triamona, 2,4,6-trinitorbenzene (TATB, C 6 H 6 N 6 O 6) assembly with ":" representing the electron lone pair of nitrogen or oxygen at the molecular interfaces. It is uncovered that: (i) the N H bond possesses the negative compressibility and negative thermal expansivity; (ii) the C (N 2H) bond undergoes both compressive and thermal contraction; (iii) the (O,N):H and rest interactions follow the regular compressibility and thermal expansivity. The unusual response of the H N bond in TATB to perturbation is the same to the H O segment of the O:H O bond of water ice and the N:H O bond of the cyclo -N 5 −:4H 3 O+ complexes, which proves that the O:⇔:N repulsion couples the inter-(O:H) and the intramolecular (H N) interactions and drives the O:H N to relax cooperatively in the segmental length, energy, and vibration frequency when subjecting to perturbation. Discoveries demonstrate not only the significance of molecular coupling interactions but also the power of mechanical and thermal perturbations that enable detailed information of individual bond relaxation, advancing the engineering in chemistry and devising of functional molecular materials. [ABSTRACT FROM AUTHOR]