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Polymerizable deep eutectic solvents (PDES) represent a novel class of ionic liquids characterized by the presence of polymerizable groups in their hydrogen‐bond donor or acceptor components. Within the realm of flexible electronics, PDES is emerged as a promising material for the fabrication of sensors that exhibit both flexibility and stretchability. This research employs the UV‐initiated photocopolymerization of a ternary PDES composed of choline chloride (ChCl), 2‐hydroxyethyl acrylate (HEA), and itaconic acid (IA), to synthesize an ionic conductive elastomer (ICE) that boasts desirable comprehensive performances, which can be controlled by meticulously adjusting the ratios of these components. The fabrication process is streamlined and efficient, utilizing cost‐effective and eco‐friendly materials. This elastomer exhibits favorable ionic conductivity (1.70 × 10−2–5.45 × 10−2 S m−1), mechanical strength (0.48–1.21 MPa stress at break, 395–701% elongation at break), adhesion capacity (49–120 kPa adhesion strength), and sensing sensitivity toward human motions. [ABSTRACT FROM AUTHOR]

Adoption of multitarget, cost‐effective fixed‐dose medication combinations can help lower the pill load without increasing the risk of adverse events. In this study, three new 1:1 drug‐drug binary solid forms of panobinostat (PNB) and nonsteroidal anti‐inflammatory drugs (NSAIDs) were effectively synthesized by liquid‐assisted grinding and slow evaporation crystallization techniques. The obtained solid forms were extensively characterized by various analytical techniques. The structural investigation revealed that all molecular adducts formed salt with a comparable R42${\mathrm{R}}_4^2$(10) graph set pattern created by heteromeric interactions formed between PNB and corresponding salt formers. To determine the dissolving behavior of the newly developed adducts, solubility tests were performed at various pH levels (pH 1.2 and pH 7), and the results indicated that the solubility of all forms is increased at pH 7.0, particularly PNB.NIF has a solubility of 0.195 mg/mL, which is seven times higher than the parent drug. Furthermore, PXRD was used to assess the stability of the synthesized adduct at varied temperature and humidity levels and it was found that all the adducts are stable. Based on the findings, we hope that the newly found PNB drug‐drug binary adducts have possible potential to broaden the use of drug combinations without changing the chemical structures. [ABSTRACT FROM AUTHOR]

Lightweight, flexible, and thermostable thermally conductive materials are essential for enhancing heat dissipation efficiency in advanced electronics. The development of intrinsic thermally conductive polymers is the key to expanding the space for improving the thermal conductivity of polymer‐based thermal management materials. In order to balance the thermal conductivity and mechanical performance of bulk polymers, thermally conductive aramid nanofiber (ANF) films are assembled by manipulating the proton‐donating ability of solvents. Compared to water as a conventional proton donor, ethanol‐induced multi‐scale structures composed of dense hydrogen bonding interaction, large grain size, and uniform fiber topology endow the resulting ANF films with enhanced intrinsic thermal conductivity up to 5.05 W m−1 K−1 with a 34% increase, salient mechanical performance with the tensile strength of 181.4 MPa, and exceptional thermal stability higher than 500 °C. These outstanding properties of ANF films provide many possibilities for the preparation of polymer‐based thermally conductive materials. [ABSTRACT FROM AUTHOR]

Birefringent crystals, which possess optical anisotropy, are important optical components. However, designing and synthesizing birefringent crystals faces the challenge of achieving anisotropic structures, especially coplanar geometries. Herein, we achieve a significant birefringence in an ionic compound (C5H6ON)+(NO3)−, (4‐hydroxypyridinium nitrate, 4HPN) by hydrogen bonding between planar donors and planar acceptors. We demonstrate that the interactions between the planar hydrogen bond donor ((C5H6ON)+) and planar hydrogen bond acceptor ((NO3)−) ensure the coplanarity during the crystal packing, generating the desired giant optical anisotropy. On two manually cut crystal chips, we observe a Δnobv. ${\Delta {n}^{obv.}}$ =0.494 ( Δnmaxcal. ${\Delta {n}_{max}^{cal.}}$ =0.593), which is the largest among nitrates, or hydroxypyridinium derivatives. This Δnobv. ${\Delta {n}^{obv.}}$ value already surpasses those of the benchmark crystals, e.g., YVO4 and CaCO3, commonly used in the UV to visible and near IR spectral range. 4HPN also exhibits a strong second harmonic generation response (9.55×KDP). This strategy offers a promising avenue for the design and development of birefringent crystals with potential applications in optical communication, sensing and signal processing devices. [ABSTRACT FROM AUTHOR]

To extend the rule‐based approach for hydrogen abstraction reactions from oxygenated compounds, a systematic investigation was performed to examine the reactivity of gas‐phase hydrogen abstraction reactions from alkyl groups (methyl and ethyl groups) bound to oxygen atoms in five types of oxygenated compounds (alcohols, ethers, formate esters, acetate esters, and carbonate esters) by H atoms and HO2 radicals comprehensively considering rotational conformers. Quantum chemical calculations were conducted at the CBS‐QB3 level for stationary points. Rate constants were determined employing conventional transition state theory (TST). For hydrogen abstraction reactions by H, the rotational conformer distribution partition function was employed to approximate partition functions, owing to the similarity in vibrational energy‐level structures among conformers. In hydrogen abstraction reactions by HO2, the vibrational structures of transition‐state (TS) conformers varied significantly due to the hydrogen bonding, leading to an inappropriate evaluation of rate constants when using the lowest‐energy conformer as a representative. Therefore, the rate constants were calculated by the multi‐structural TST. It was revealed that the differences in functional groups containing O atoms mainly affect the bond dissociation energies of the C–H bonds and the activation energies of hydrogen abstraction reactions only when the C atoms are adjacent to the O atoms. Additionally, it was found that hydrogen bonds formed in the TSs show minor effect on rate parameters for the overall rate constants, apart from the reduction of the pre‐exponential factors for the H‐abstraction reactions from the methylene position of ethyl groups. The comparison with the rate constants from previous studies showed reasonable results, indicating that the rate constants in this study, which thoroughly consider rotational conformers, can be the current best estimates. [ABSTRACT FROM AUTHOR]

Aluminum air batteries have great potential as a state-of-the-art energy storage device due to their high capacity, energy density and fascinating safety. However, the disturbing hydrogen evolution reaction (HER) of the Al anode increase the gap between practical application and theoretical level. Electrolyte engineering with organic additives has been the spotlight to address the problem of HER. The polar functional group of organic molecules could bound with the water via the hydrogen bond to drop the activity of water. Unfortunately, the basic physicochemical properties of electrolyte would be deteriorated due to the organic matter, which has a negative impact on the electrochemical performance of batteries. Herein, an inorganic additive was adopted to regulate the hydrogen bond network and anode interface. The activity of H 2 O could be obviously suppressed by the stronger three-center-four-electron hydrogen bonds bridged by fluoride ions. And the water molecules are kept away from the anode surface due to the protective layer caused by the adsorption of fluoride ions. The HER could be greatly inhibited by both pathways, which reaches an inhibition efficiency of 55% in the electrolyte with 5 M KF. Correspondingly, the Al air battery exhibits a high discharge specific capacity of 1552.8 mAh g−1 and an energy density of 1829.51 Wh kg−1 at a current density of 25 mA cm−2. This work showcases a promising inorganic additive to suppress the HER for high-performance Al air battery. [Display omitted] • An inorganic additive was adopted to regulate hydrogen bond network. • The 3c4e hydrogen bond bridged by fluoride ion decreases the activity of H 2 O. • The fluoride ions constructure a protective layer for anode. • Al air battery exhibits high discharge capacity of 1552.8 mAh g−1 at 25 mA cm−2. [ABSTRACT FROM AUTHOR]

In the title mol­ecule, C20H18ClN3O2, the 2-chloro­phenyl group is disordered to a small extent [occupancies 0.875 (2)/0.125 (2)]. The phenyl­acetamide moiety is nearly planar due to a weak, intra­molecular C—H⋯O hydrogen bond. In the crystal, N—H⋯O hydrogen bonds and π-stacking inter­actions between pyridazine and phenyl rings form helical chains of mol­ecules in the b-axis direction, which are linked by C—H⋯O hydrogen bonds and C—H⋯π(ring) inter­actions. A Hirshfeld surface analysis was performed, which showed that H⋯H, C⋯H/H⋯C and O⋯H/H⋯O inter­actions to dominate the inter­molecular contacts in the crystal. [ABSTRACT FROM AUTHOR]

The title molecule, C25H23BrN2O2, adopts a cup shaped conformation with the distinctly ruffled imidazolidine ring as the base. In the crystal, weak C-HO hydrogen bonds and C-H...π(ring) interactions form helical chains of mol- ecules extending along the b-axis direction that are linked by additional weak C-H π(ring) interactions across inversion centres. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from HH (51.0%), CH/HC (21.3%), Br...H/ HBr (12.8%) and OH/HO (12.4%) interactions. The volume of the crystal voids and the percentage of free space were calculated to be 251.24 ų and 11.71%, respectively, showing that there is no large cavity in the crystal packing. Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the stabilization is dominated by the dispersion energy. [ABSTRACT FROM AUTHOR]

A new aluminum complex (NSO)AlMe2 featuring a hydrogen bond donor on the ligand backbone has been synthesized via the reaction of AlMe3 with 1-((2-(isopropylamino)phenyl)thio)propan-2-ol (NSO-H) and spectroscopically characterized. In the complex, the aluminum atom is in a distorted tetrahedral coordination sphere determined by the anionic oxygen and neutral nitrogen atoms of the ligand and by the two carbon atoms of the alkyl groups. After proper activation, the complex (NSO)AlMe2 was able to promote the ring-opening polymerization of L-, rac-lactide, ε-caprolactone and rac-β-butyrolactone. The polymerization of rac-lactide was faster than that of L-lactide: in a toluene solution at 80 °C, the high monomer conversion of 100 equivalents was achieved in 1.5 h, reaching a turnover frequency of 63 molLA·molAl–1·h–1. The experimental molecular weights of the obtained polymers were close to those calculated, assuming the growth of one polymer chain for one added alcohol equivalent and the polydispersity indexes were monomodal and narrow. The kinetic investigation of the polymerization led to the determination of the apparent propagation constants and the Gibbs free energies of activation for the reaction; the terminal groups of the polymers were also identified. The complex (NSO)AlMe2 was active in harsh conditions such as at a very low concentration or in the melt using technical-grade rac-lactide. A relatively high level of activity was observed in the ring-opening polymerization of ε-caprolactone and rac-β-butyrolactone. DFT calculations were performed and revealed the central role of the NH function of the coordinated ligand. Acting as a hydrogen bond donor, it docks the monomer in the proximity of the metal center and activates it toward the nucleophilic attack of the growing polymer chain. [ABSTRACT FROM AUTHOR]

Biologically active compounds are highly sought‐after materials for developing novel structures applicable to industry. Cytosine and pyridine‐2,3‐dicarboxylic acid (quinolinic acid) are notably significant environmentally. Cytosine, a pyrimidine derivative, features a six‐membered ring with a ketone and an amino group, constituting a fundamental nitrogenous base found in deoxyribonucleic acid (DNA). The present synthesis yielded a salt of dipyridine‐2,3‐dicarboxylic acid with cytosine, wherein a proton was transferred from a carboxyl group of quinolinic acid to a ring N atom in the cytosine molecule giving the salt 6‐amino‐2‐oxo‐2,3‐dihydropyrimidin‐1‐ium 3‐carboxypyridine‐2‐carboxylate, C4H6N3O+·C7H4NO4−. A Hirshfeld surface analysis was conducted to examine the contribution of contacts within the salt. The structure of the salt was compared to other structures containing quinolinic acid in the Cambridge Structural Database (CSD). [ABSTRACT FROM AUTHOR]

This study delves into the nature of individual hydrogen bonds and the relationship between metal cations and hydrogen bonding in the Watson–Crick guanine–cytosine (GC) base pair and its alkali and alkaline earth cation‐containing complexes (Mn+–GC). The findings reveal how metal cations affect the nature and strength of individual hydrogen bonds. The study employs interacting quantum atoms (IQA) analysis to comprehensively understand three individual hydrogen bonds within the GC base pair and its cationic derivatives. These analyses unveil the nature and strength of hydrogen bonds and serve as a valuable reference for exploring the impact of cations (and other factors) on each hydrogen bond. All the H⋯D interactions (H is hydrogen and D is oxygen or nitrogen) in the GC base pair are primarily electrostatic in nature, with the charge transfer component playing a substantial role. Introducing a metal cation perturbs all H⋯D interatomic interactions in the system, weakening the nearest hydrogen bond to the cation (indicated by a) and reinforcing the other (b and c) interactions. Notably, the interaction a, the strongest H⋯D interaction in the GC base pair, becomes the weakest in the Mn+–GC complexes. A broader perspective on the stability of GC and Mn+–GC complexes is provided through interacting quantum fragments (IQF) analysis. This approach considers all pairwise interactions between fragments and intra‐fragment components, offering a complete view of the factors that stabilize and destabilize GC and Mn+–GC complexes. The IQF analysis underscores the importance of electron sharing, with the dominant contribution arising from the inter‐fragment exchange‐correlation term, in shaping and sustaining GC and Mn+–GC complexes. From this point of view, alkaline and alkaline earth cations have distinct effects, with alkaline cations generally weakening inter‐fragment interactions and alkaline earth cations strengthening them. In addition, IQA and IQF calculations demonstrate that the hydration of cations led to small changes in the hydrogen bonding network. Finally, the IQA interatomic energies associated with the hydrogen bonds and also inter‐fragment interaction energies provide robust indicators for characterizing hydrogen bonds and complex stability, showing a strong correlation with total interaction energies. [ABSTRACT FROM AUTHOR]

Amidine‐substituted allosteric receptors 2 a and 2 b for benzenediols were synthesized. Receptor 2 a with five‐membered amidines exhibited greater allostericity than the amide‐substituted receptor 1, while 2 b with six‐membered amidines exhibited less allostericity. NMR titration experiments revealed that a significant enthalpic factor was involved in the allostericity of these receptors. X‐ray and DFT optimized structures of 2 a and 2 b revealed that 2 a adopted a coplanar conformation with π‐conjugation between the amidines and the phenylene ring of the hydrindacene framework, resulting in high allostericity due to inactivation of the initial binding. [ABSTRACT FROM AUTHOR]

2-Amino-5-nitro-4-(tetrazol-5-yl)-1,2,3-triazole (HANTT), its corresponding energetic salts and a dimeric azo compound are successfully synthesized. Compared to 5-nitro-4-(tetrazol-5-yl)-1,2,3-triazole (H2 NTT), the neutral N -amino compound HANTT exhibits excellent properties in many aspects, including a higher density (ρ = 1.86 g cm–3), a better detonation performance (Dv = 8931 m s–1 , P = 32.2 GPa) and a higher thermal decomposition temperature (Td = 237 °C). Among the prepared materials, the hydroxylammonium energetic salt exhibits the best detonation performance (Dv = 9096 m s–1 , P = 32.8 GPa) and an acceptable mechanical sensitivity (IS = 12 J, FS = 144 N). HANTT, the energetic salts and the azo compound are fully characterized by infrared spectroscopy, multinuclear NMR spectroscopy, elemental analysis and differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

Supramolecular polymers offer an intriguing possibility to transfer molecular properties from the nano‐ to the mesoscale. Towards this achievement, seed‐initiated supramolecular polymerization has emerged as a powerful tool, as it prevents unlimited growth and enables size control of the assembly outcome. However, the potential application of the seeding method in the context of complex supramolecular systems is hitherto unclear. Herein we demonstrate that minute differences in molecular design in direct proximity to intermolecular recognition sites govern the molecular packing and in turn dictate the efficacy of seeded polymerization processes. We introduce a stepwise increase in steric demand in the central amino acid residue of a diamide system, which gradually increases the rotational displacement within the aggregated state. This fine‐tuning of the molecular packing directly affects the propensity of the different aggregates to act as seeds for the other supramolecular synthons. In turn this allows us to selectively target specific trapped monomer states in binary mixtures for social or narcissistic seeded polymerization. [ABSTRACT FROM AUTHOR]

It is a great challenge to manufacture room‐temperature blue long afterglow phosphorescent materials adapted to environmental conditions. Herein, an Na‐based metal‐organic framework (MOF) was constructed using Na+ and 1H‐1,2,4‐triazole‐3,5‐dicarboxylic acid, which exhibits long‐lived of 378.9 ms, deep blue and room‐temperature phosphorescence, meanwhile possesses the visible blue afterglow for 3~6 seconds after removing excitation light source. The three‐dimensional coordination bonds network provided by Na‐based MOF protects the organic ligands intrinsic hydrogen bond network, resulting in the phosphor lifetime and residual color remaining unchanged in different gas atmospheres. Furthermore, first‐principles time‐dependent density functional theory reveals that the rigid Na‐based MOF structure can limit the rotation and vibration of the room‐temperature phosphorescent organic ligands. This limitation results in the suppression of non‐radiative decay for both singlet and triplet excitons, promotes intersystem crossing, and increases the rate of radiative decay, ultimately achieving long‐lived room‐temperature phosphorescence. [ABSTRACT FROM AUTHOR]

Homogeneous electrocatalysts typified by transition‐metal complex show transcendent potency in efficient energy catalysis through molecular design. For example, metal complexes with elaborate design performed wonderful activity and selectivity for electrocatalytic CO2 reduction. Primary coordination sphere of metal complexes plays a key role in regulating its intrinsic redox properties and catalytic activity. However, the overall reduction efficiency of CO2 is also bound up with the substrate activation process. Transition‐metal complexes are hoped to exhibit reasonable redox potential, reactive activity, and stability, while binding and activating CO2 molecules to achieve efficient CO2 reduction. Construction of second coordination sphere, especially hydrogen‐bonding network of transition‐metal complexes, is reported to be the “kill two birds with one stone” strategy to realize efficient CO2 reduction catalysis via systematic catalyst properties modulation and substrate activation. Herein, we present recent progress on the construction of hydrogen‐bonding network in the second coordination sphere of metal complexes by ligand modification or the introduction of exogenous organic ligand, and the resulted productive enhancement of the catalytic performance of metal complexes by the improvement of adsorption capacity and activation of CO2, proton transfer rate, and stability of reaction intermediates, and so forth. [ABSTRACT FROM AUTHOR]

Self‐healing research based on commercial polymeric materials (such as polyurethane) is beneficial to sustainable development by prolonging the life of materials. However, developing polymeric materials that integrate robust mechanical properties with self‐healing ability at ambient temperature remains a formidable challenge. The formation of polymeric materials by physically and chemically dual crosslinking structures is a powerful method to improve mechanical properties. Herein, a series of dual crosslinking self‐healing polyurethane have been designed and successfully synthesized by incorporating 2‐ureido‐4[1H]‐pyrimidinone (UPy) units and triethanolamine (TEOA) into the polymer networks. Relying on the reinforcement of chemical crosslinking which is induced by TEOA, the resulting polyurethane exhibited robust strength of 10.3 MPa and elongation at break of 569.4%, which are quite prominent compared with previous reports. At the same time, the recombination of hydrogen bonds makes the polyurethane with UPy structure achieve rapid self‐healing after 24 h at 40°C and the strength recovered to 4.98 MPa. This work provided a novel way to fabricate sustainable polyurethane with robust mechanical properties. [ABSTRACT FROM AUTHOR]

Low‐dimensional organic–inorganic hybrid perovskites (OIHPs) have attracted extensive attention due to their outstanding photoluminescence properties. However, the charge transfer between the organic A‐site and the inorganic framework is impeded, resulting in lower photoluminescence quantum yield (PLQY). Herein, m‐xylylenediamine (MXD) is incorporated into the perovskite, realizing the synthesis of a series of 0D perovskite‐like single crystals, i.e., (MXD)2PbX6 (X = Cl, Br, I). Density functional theory (DFT) calculations reveal the presence of effective hydrogen bonding between MXD and [PbX6]4−, which is enhanced through the controlled modification of halogen sites, enables the establishment of efficient charge transfer channels, and facilitates charge migration. Accordingly, (MXD)2PbCl6 achieves a PLQY as high as 55.9% at 460 nm, characterized by blue light emission and remarkable air stability. [ABSTRACT FROM AUTHOR]

Although a variety of functional polyvinyl alcohol hydrogels (PVAHG) with attractive mechanical and electrochemical properties have been fabricated using traditional freeze‐thaw cycling, this approach is usually relatively complicated, time‐consuming and relies essentially on the use of PVA chains with a weight‐average molecular weight above 60000. Here a new strategy capable of assembling relatively low‐molecular‐weight (≈30000) polyvinyl alcohol (PVA) into highly crosslinked physical hydrogels is developed. By exploiting ammonium persulfate as a simple and versatile oxidant to simultaneously provide oxidizing and salting‐out effects to the polymeric building blocks, PVAHG with excellent and tailorable elasticity, conductivity and sensitivity can be achieved building on the strong intermolecular hydrogen bonding between the newly formed ─COOH and ─CHO terminations and the inclusion of abundant inorganic ions. The hydrogels cannot only act as effective wearable wireless sensors for detecting output resistance signals but also be further employed to construct a motion‐mapped self‐propelled robotic arm that is able to instantly and accurately map the motion of human bodies. This study may provide new insights into polymer chemistry, hydrogel sensing, and soft robotics. [ABSTRACT FROM AUTHOR]

Context: Organic cocrystals have a wide range of applications in the field of optics due to their photo responsive property. We present here a newly synthesized phenazine 2-hydroxynaphthalene (1:1) cocrystal, its structural and theoretical calculations which tend to the nonlinear optical property. In the crystal structure of the title cocrystal, the phenazine and 2-hydroxynaphthalene molecules from one- and two-dimensional supramolecular frameworks via O‒H...N hydrogen bonds and C‒H...N, C‒H...π interaction, respectively. The phenazine molecules from an infinite off-set stacking through π...π interaction in the three-dimensional molecular packing of the title cocrystal. The contribution of intermolecular interaction in the three-dimensional molecular packing and the interaction energy calculation is studied by the Hirshfeld surface analysis. The molecular geometry retrieved from the experimental X-ray diffraction analysis is in good agreement with the theoretically calculated parameters. Further, the molecular electrostatic potential (MEP) and frontier molecular orbital (FMO) analysis have been carried out to study the charge distribution and molecular reactive mechanism. Third-order nonlinear optical property of the cocrystals has been analyzed by Z-scan measurements. The determined nonlinear optical absorption coefficient value 6.442 × 10−05 (m/W) and the nonlinear refractive index value − 5.535 × 10−2 (m/W) suggest that the crystalline solid can be a good choice of potential nonlinear optical material. Method: The crystal structures of phenazine 2-hydroxynaphthalene cocrystal was solved by direct methods procedure using SHELXS program and refined by full-matrix least square procedure on F2 using SHELXL-2018 program on Olex2 software. The computational calculation has been carried out using DFT/B3LYP quantum chemical function with triple zeta 6–311 + + basis set in the ground state molecular stability using Gaussian 09W program suite. The Hirshfeld surface analysis mapping, associated 2D fingerprint plot, and intermolecular molecular interaction energy calculations were carried out using CrystalExplorer (version 21.5) software. [ABSTRACT FROM AUTHOR]

Context and results: The structure, mechanical, electronic, vibration, and hydrogen bonding properties of a novel high-energy and low-sensitivity 5, 5′-dinitroamino-3, 3′-azo-oxadiazole 4, 7-diaminopyridazino [4, 5-c] furoxan salt have been studied by density functional theory. The calculated vibrational properties show that the low-frequency mode is mainly contributed by the vibration of the -NO2 group, and the high-frequency mode is mainly contributed by the vibration of the -NH2 group and the N7-H3 bond which protonates the cation. In addition, it is analyzed that the first bond to break may be the N-NO2 bond. The calculated hydrogen bond properties indicate that the hydrogen bond between water molecules and cations is N7-H3... O5 (1.563 Å), which is the shortest hydrogen bond among all hydrogen bonds. The presence of this exceptionally short hydrogen bond renders the N7-H3 and H6-O5 bonds resistant to disruption at high frequencies, underscoring the pivotal role of hydrogen bonding in stabilizing the structure of energetic materials. Given the absence of experimental and theoretical data on the electronic, mechanical, and vibrational properties of the material thus far, our calculations offer valuable theoretical insights into the ionic salts of high energy and low sensitivity. Computational methods: All calculations have been carried out based on density functional theory (DFT) and implemented in the CASTEP code. The mode-conserving pseudopotential is utilized to describe the plane wave expansion function, while the PBE functional within the generalized gradient approximation (GGA) is employed to characterize the exchange–correlation interaction. Additionally, dispersion correction is applied using Grimme's DFT-D method. [ABSTRACT FROM AUTHOR]

Isoguanosine (isoG) is a natural structural isomer of guanosine (G) with significant potential for applications in ionophores, genetics, gel formation, and cancer therapy. However, the cost of commercially available isoG on a gram scale is relatively high. To date, a detailed method for the large‐scale preparation of high‐purity isoG has not been reported. This study presented a simple and convenient approach for the large‐scale synthesis of isoG through the diazotization of 2,6‐diaminopurine riboside with sodium nitrite and acetic acid at room temperature. Further, this method could synthesize isoG derivatives (2'‐fluoro‐isoguanosine (1) and 2'‐deoxy‐isoguanosine (2)) from 2,6‐diaminopurine nucleoside derivatives using diazotization. The structural information of natural and modified nucleosides is crucial for the modification and substitution of DNA/RNA. This study obtained the single‐crystal structure of isoG for the first time and analyzed it in detail using microcrystal electron diffraction. The three‐dimensional supramolecular structure of isoG adopted similarly base‐pair motifs from π‐π stacking interaction of diverse layers, intramolecular hydrogen bonding, and distinct hydrogen bonding interactions from sugar residues. This study has contributed to further isoG modification and its applications in medicinal chemistry and materials. [ABSTRACT FROM AUTHOR]

The benzimidazole moiety in the title molecule, C19H25N5O, is almost planar and oriented nearly perpendicular to the triazole ring. In the crystal, C—H...O hydrogen bonds link the molecules into a network structure. There are noμ-μinteractions present but two weak C—H...π(ring) interactions are observed. A Hirshfield surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (62.0%), H...C/ C...H (16.1%), H...N/N...H (13.7%) and H...O/O...H (7.5%) interactions. Evaluation of the electrostatic, dispersion and total energy frameworks indicate that the stabilization is dominated via the dispersion energy contributions in the title compound. [ABSTRACT FROM AUTHOR]

Two‐step sequential deposition is a widespread technique for the fabrication of perovskite films, renowned for its better control of the crystallization process. However, achieving a well‐controlled and complete reaction of PbI2 by organic ammonium salts remains a key challenge. Previous studies have predominantly focused on regulating the properties of the PbI2 layer while paying less attention to the high reactivity of organic ammonium salts. In this study, the natural molecule anethole is first explored to control perovskite crystallization during two‐step sequential deposition, focusing on the reactivity modulation of organic formamidine ion (FA+). It is demonstrated that FA+ exhibits strong hydrogen bond interactions with anethole, inhibiting the high reactivity of FA+ and effectively delaying the rapid reaction between FAI and PbI2. This decelerates the crystallization kinetics of perovskite films, facilitating the orderly and complete reaction of PbI2 by FAI while suppressing detrimental δ‐phase formation. Consequently, FA‐based perovskite films with high crystallinity, preferred orientation, and low defect state density are obtained. The fabricated planar hole transport layer‐free carbon electrode perovskite solar cells deliver an efficiency of 20.41% (certified efficiency of 20.0%), which is a new record for this kind of solar cell. [ABSTRACT FROM AUTHOR]

With the continuous development of electrochemical energy storage technology, especially in the current pursuit of environmental sustainability and safety, aqueous energy storage devices, due to their high safety, environmental friendliness, and cost‐effectiveness, are becoming an important direction of development in the field of energy storage. Diverse application scenarios require that energy storage systems be capable of continuous power supply under low temperature conditions. However, conventional aqueous electrolytes freeze at extremely low temperatures, causing limited ion transport and slow reaction kinetics, degrading the performance of the energy storage system. The design of low‐temperature anti‐freeze aqueous electrolytes has become an effective way to address this issue. In this review, the deep connection between hydrogen bonds (HBs) interactions in aqueous electrolytes and the liquid‐to‐solid conversion process, and the fundamental principles of the anti‐freeze mechanism is first explored. Subsequently, a systematic categorization and discussion of the design strategies for low‐temperature anti‐freeze aqueous electrolytes are conducted. Finally, potential directions are proposed. This review aims to provide comprehensive scientific guidance and technical reference for the development of anti‐freeze aqueous electrolytes with excellent low‐temperature performance, thereby promoting the application and innovation of aqueous energy storage devices in low‐temperature environments. [ABSTRACT FROM AUTHOR]

Elastomers with high mechanical toughness can guarantee their durability during service life. Self-healing ability, as well as recyclability, can also extend the life of materials and save the consuming cost of the materials. Many efforts have been dedicated to promoting the mechanical toughness as well as the self-healing capability of elastomers at the same time, while it remains a challenge to balance the trade-off between the above properties in one system. Herein we proposed a molecular design driven by dual interactions of acylsemicarbazide hydrogen bonding and Cu2+-neocuproine coordination simultaneously. By introducing the reversible multiple hydrogen bonds and strong coordination bonds, we successfully fabricated an extremely tough and self-healing elastomer. The elastomer can achieve an impressive top-notch toughness of 491 MJ/m3. Furthermore, it boasted rapid elastic restorability within 10 min and outstanding crack tolerance with high fracture energy (152.6 kJ/m2). Benefiting from the combination of dynamic interactions, the material was able to self-repair under 80 °C conveniently and could be reprocessed to restore the exceptional mechanical properties. [ABSTRACT FROM AUTHOR]

Ethanolamine hydrates containing from one to seven water molecules were identified via rotational spectroscopy with the aid of accurate quantum chemical methods considering anharmonic vibrational corrections. Ethanolamine undergoes significant conformational changes upon hydration to form energetically favorable hydrogen bond networks. The final structures strongly resemble the pure (H2O)3–9 complexes reported before when replacing two water molecules by ethanolamine. The 14N nuclear quadrupole coupling constants of all the ethanolamine hydrates have been determined and show a remarkable correlation with the strength of hydrogen bonds involving the amino group. After addition of the seventh water molecule, both hydrogen atoms of the amino group actively contribute to hydrogen bond formation, reinforcing the network and introducing approximately 21–27 % ionicity towards the formation of protonated amine. These findings highlight the critical role of microhydration in altering the electronic environment of ethanolamine, enhancing our understanding of amine hydration dynamics. [ABSTRACT FROM AUTHOR]

Given the abundance of functional groups, meso- and macro-pores, and a high surface area, the piperazine-based poly(amic acid) was employed as a heterogeneous catalyst in the multicomponent reaction to prepare pyrrolidinone scaffolds in a green solvent, acting as a medium for mass transfer and crystallization solvent. The important parameters of the reaction were investigated to find the optimal reaction conditions. A conversion of 100% was obtained at reflux conditions within 30–100 min using a catalytic amount of 200 mg of piperazine-based poly(amic acid) per 2 mmol of reactants (100 mg of cat./1 mmol of reactant). The piperazine-based poly(amic acid) exhibited high recyclability and the recovered catalyst could be used in successive runs without worthy loss in its activity. This work revealed the catalytic activity of the piperazine-based poly(amic acid) as a promising functional polymeric heterogeneous catalyst for organic synthesis. [ABSTRACT FROM AUTHOR]

Two novel hydrophobic deep eutectic solvents (HDESs), composed of alkyl (=Hexyl, Nonan) ethylenediaminium and menthol (Men), namely Hexen/Men and Nonen/Men, were synthesized. Hexen and Nonen primarily act as hydrogen bond acceptors, with Men serving as the principal hydrogen bond donor. After the formation of HDES, the IR absorption peaks of Hexen, Nonen's–NH2, and Men–OH fused into a wider peak, the 1H-NMR spectra of Men–OH, shifted to a lower field. Furthermore, a significant redshift approximately 300 cm−1 was detected in the vibrational frequency of the Men–OH functional group when performing density functional theory (DFT) calculations for the HDESs. These results support the development of stronger O–H···N bonds between Hexen/Nonen–NH2 and Men–OH, and the calculated sum of hydrogen bonding energy was approximately 56 mol·kg–1, categorizing it as an intermediate-strength hydrogen bond. Both HDESs have ethylenediamine polar heads in their hydrogen bond acceptors, which have chelating characteristics that help them coordinate with transition metal ions. Metal ions such as Cu(II), Co(II), and Ni(II) were successfully extracted from aqueous solutions at a concentration of 10 mmol·L–1using HDESs. The Cu(II) and Ni(II) extraction efficiencies exceeded 90%, indicating their effectiveness. Notably, even at higher metal ion concentrations (100 mmol·L–1), the extraction efficiencies of all three metal ions remained consistently below 80%. This indicates that the HDESs can suitably collect trace metal ions. [ABSTRACT FROM AUTHOR]

Hydrogen-bonded interactions of organic acids play crucial role in many chemical and biochemical processes vital for life's maintenance. They are important as well in the context of secondary aerosol formation in the atmosphere. In the present work, we study the nature of hydrogen-bonded acid–base interactions present in the binary clusters of vanillic acid, a natural phenolic compound found in various plants and also observed in Amazonian aerosol, with common atmospheric bases such as ammonia and methylamines (mono-, di-, and tri-methylamine). Detailed and systematic quantum-chemical DFT calculations have been performed to analyze the structural, energetic, electrical, and spectroscopic properties of the clusters. The presence of strong intermolecular hydrogen-bonds and large binding electronic energies indicates that vanillic acid interacts strongly with atmospheric molecules. Scattering intensities of radiation (Rayleigh activities) are found to increase with cluster formation. The changes in binding free energy and enthalpy of formation of the vanillic acid-ammonia/amine binary clusters at lower temperatures demonstrate increased thermodynamical stability. [ABSTRACT FROM AUTHOR]

Polymer flooding is one of the most effective tertiary oil recovery technologies, which can significantly improve the sweep efficiency of the reservoir by injecting high-viscosity polymer solution. However, Conventional polymers are difficult to inject, easy to degrade after shearing, cause plugging in low-permeability reservoirs, functional monomers have potential environmental pollution risks, and limit its industrial application. In recent years, more and more attention has been paid to the development of adaptive supramolecular oil displacement materials from bio-based materials. Here, the bases of guanine and cytosine from ribonucleic acid are grafted onto polyacrylamide. With a multi-supramolecular interactions through synergistic hydrogen bonding and hydrophobic interactions, HPAM-C≡G-HPAM with excellent injectivity and high viscosity are developed to improve the recovery of low permeability reservoirs. Subsequently, HPAM-C≡G-HPAM was characterized by FT-IR, NMR, ESEM and DLS. The rheological test results show that the tackifying ability of the supramolecular system is much higher than that of polyacrylamide with the same molecular weight and has excellent shear resistance. In the laboratory core displacement experiment, the injection pressure of HPAM-C≡G-HPAM in low permeability core is only 1/3 of that of polyacrylamide with the same viscosity, and the oil recovery can be increased by 16.31%, The oil recovery can be increased by 10% under high temperature and high salinity conditions. Accordingly, HPAM-C≡G-HPAM has the potential to greatly enhance oil recovery in low permeability reservoirs. [ABSTRACT FROM AUTHOR]

Lithium hexafluorophosphate (LiPF6), the most commonly used lithium battery electrolyte salt, is vulnerable to heat and humidity. Quantitative and qualitative determination the variation of LiPF6 have always relied on advanced equipment. Herein, we develop a fast, convenient, high-selective fluorescence detection method based on metal--organic cages (MOC), whose emission is enhanced by nearly 20 times in the presence of LiPF6 with good stability and photobleaching resistance. The fluorescent probe can also detect moisture in battery electrolyte. We propose and verify that the luminescence enhancement is due to the presence of hydrogen bond-induced enhanced emission effect in cages. Fluorescent excitation-emission matrix spectra and variable-temperature nuclear magnetic resonance spectroscopy are employed to clarify the role of hydrogen bonds in guest-loaded cages. Density functional theory (DFT) calculation is applied to simulate the structure of host-guest complexes and estimate the adsorption energy involved in the system. The precisely matched lock-and-key model paves a new way for designing and fabricating novel host structures, enabling specific recognition of other target compounds. [ABSTRACT FROM AUTHOR]

Designing and making sustainable plastics is especially urgent to reduce their ecological and environmental impacts. However, it remains challenging to construct plastics with simultaneous high sustainability and outstanding comprehensive performance. Here, a composite strategy of in situ polymerizing a petroleum‐based monomer with the presence of an industrialized bio‐derived polymer in a quasi‐solvent‐free system is introduced, affording the plastic with excellent mechanical robustness, impressive thermal and solvent stability, as well as low energy, consumes during production, processing, and recycling. Particularly, the plastic can be easily processed into diverse shapes through 3D printing, injection molding, etc. during polymerization and further reprocessed into other complex structures via eco‐friendly hydrosetting. In addition, the plastic is mechanically robust with Young's modulus of up to 3.7 GPa and tensile breaking strength of up to 150.2 MPa, superior to many commercially available plastics and other sustainable plastics. It is revealed that hierarchical hydrogen bonds in plastic predominate the well‐balanced sustainability and performance. This work provides a new path for fabricating high‐performance sustainable plastic toward practical applications, contributing to the circular economy. [ABSTRACT FROM AUTHOR]

Non‐centrosymmetric organics are promising nonlinear optical (NLO) candidates, which always exhibit a short UV absorption cutoff edge, and a strong second harmonic generation (SHG) response, but an overlarge birefringence. Here, in order to optimize the birefringence, the methyl modulation of π‐conjugated organic planar units is proposed and implemented with the urea structure as a template. Thus, N‐methylurea and N,N'‐dimethylurea crystals are obtained by partially replacing hydrogen atoms with methyl groups. This replacement reduces hydrogen donors and weakens interchain hydrogen bonds, which facilitates the decreasing density and the parallel arrangement of π‐conjugated planar units. Hence, both N‐methylurea and N,N'‐dimethylurea crystals exhibit not only an optimized birefringence (N‐methylurea ≈0.099 and N,N'‐dimethylurea ≈0.072 at 546 nm) but also an enhanced SHG response (N‐methylurea ≈1.2 × β‐BaB2O4 and N,N'‐dimethylurea ≈1.9 × β‐BaB2O4), while maintaining a short UV absorption cutoff edge. Therefore, this work provides a novel strategy for the structural design and performance modulation of organic NLO crystals. [ABSTRACT FROM AUTHOR]

This paper proposes a molecular model of covalent grafting of azobenzene derivatives with graphite-like carbon nitride based on hydrogen bond regulation to improve the azobenzene photothermal energy storage density. The enthalpy of isomerization (Δ H) of azobenzene molecular cis - trans isomers is calculated using density functional theory, and the magnitude of Δ H is used to evaluate the photothermal storage performance of the azobenzene graphite-like carbon nitride model. The results showed that the molecular Δ H value increased by 0.105–0.243 eV after the azobenzene derivatives were covalently grafted to the graphitic carbon nitride template. In addition, when the donator group replaced the active benzene ring ortho-site of azobenzene, its value was 0.069–0.295 eV higher than that of the electron-withdrawing groups. Moreover, intramolecular hydrogen bonds can stabilize cis - trans isomers and increase the energy of azobenzene. Compared with unsubstituted azobenzene, the energy of azobenzene Δ H containing one intramolecular hydrogen bond increased by 0.295 eV, while the energy of azobenzene Δ H containing multiple intramolecular hydrogen bonds increased by 0.775 eV. [Display omitted] • A molecular model for covalent grafting of azobenzene onto g-C 3 N 4 with hydrogen bond was developed. • The energy conversion density of azobenzene synthetic was determined using density functional theory. • The grafting effect was evaluated by considering intramolecular hydrogen bond, substitution location, and electron group. [ABSTRACT FROM AUTHOR]

A unique compound (compound 1) with structural features including an unprecedented tridentate-bridging coordination mode of permanganate ions and an eight-coordinated (rhombohedral) κ1-chlorido and tridentate permanganato ligand in a potassium complex containing coordination polymer (CoIII(NH3)6]n[(K(κ1-Cl)2(μ2,2′,2″-(κ3-O,O′,O″-MnO4)2)n∞) with isolated regular octahedral hexamminecobalt(III) cation was synthesized with a yield of >90%. The structure was found to be stabilized by mono and bifurcated N-H∙∙∙Cl and N-H∙∙∙O (bridging and non-bridging) hydrogen bonds. Detailed spectroscopic (IR, far-IR, and Raman) studies and correlation analysis were performed to assign all vibrational modes. The existence of a resonance Raman effect of compound 1 was also observed. The thermal decomposition products at 500 °C were found to be tetragonal nano-CoMn2O4 spinel with 19–25 nm crystallite size and KCl. The decomposition intermediates formed in toluene at 110 °C showed the presence of a potassium- and chloride-containing intermediates combined into KCl during aqueous leaching, together with the formation of cobalt(II) nitrate hexahydrate. This means that the CoIII–CoII redox reaction and the complete decomposition of the permanganate ions occurred in the first decomposition step, with a partial oxidation of ammonia into nitrate ions. [ABSTRACT FROM AUTHOR]

Photoconductors featuring an individual micro/nano‐crystal as the photoactive channel hold the great promise for next‐generation integrated optoelectronics. Meanwhile, the gain aiming for signal amplification without an extra amplifier, the fast response for fast data transfer, and low dark current for weak signal acquisition are highly desirable in integrated optoelectronics, but are inherent trade‐off in traditional photoconductors. Herein, the study demonstrates a single‐microplate MAPbI3 photoconductor based on polyvinyl alcohol‐filled planar electrodes that can simultaneously achieve excellent performance on these parameters. The superior performance can be attributed to the exquisite design of filling the device channel gap with polyvinyl alcohol. This deep‐work‐function transparent polyvinyl alcohol can not only passivate surface defects of the perovskite microplate by hydrogen bonding, but also form a heterojunction with top perovskites to induce a depleted channel. Resultant single‐microplate photodetectors exhibit exceptional performance characteristics including ultra‐low noise‐equivalent power of 0.19 fW Hz−1/2, high specific detectivity of 3.68 × 1014 Jones, fast response of 3.2 µs, high EQE‐bandwidth over 107 Hz, as well as excellent stability. More importantly, single‐microplate MAPbI3 photoconductors demonstrate ultra‐weak‐light imaging ability surpassing silicon counterparts. Furthermore, the successful integration of their microplate pixels showcases the promising prospect for integrated optoelectronics. [ABSTRACT FROM AUTHOR]

It has been difficult to detach abrasive particles smaller than 50 nm from polished surfaces in post-CMP cleaning. During the cleaning process, the residual nano-particles exert shear force in the inevitable shear flow. In order to understand the cleaning mechanism, it is indispensable to investigate not only the force but also the energy acting on different-sized nano-particles. In this article, we proposed the evaluation of detachment energy (the energy required to detach nano-particles) by using Lateral Force Microscopy. As an example, the dominant detachment energy of the silica nano-particle between the oxide film is the potential energy of the hydrogen bond. It suggested that the silica nano-particle detachment involves the breaking of hydrogen bonds. [ABSTRACT FROM AUTHOR]

This work involved synthesizing three N‐benzyl‐4‐hydroxybenzylamines using indirect reductive amination of aromatic aldehydes and 4‐hydroxybenzylamine. Such benzylamines' reaction with formaldehyde produced tricyclic azacyclophanes formed by two benzylamine units joined by methylene bridges. Computational calculations established that macrocyclization was promoted by template formation stabilized by hydrogen bonds and π‐stacking. [ABSTRACT FROM AUTHOR]

Polymer flooding, using hydrolyzed polyacrylamide (HPAM), is crucial in enhanced oil recovery technology. The effect of the HPAM and NaCl concentration on the stability of the simulated emulsions was assessed through multiple light scattering experiments. The results demonstrated that HPAM significantly enhanced the stability of both oil‐in‐water (O/W) and water‐in‐oil (W/O) emulsions. The HPAM concentration escalated from 200 mg L−1 to 1000 mg L−1, increasing from 1.24% to 1.31% at 60 minute in the average backscattering of W/O emulsions. The average transmittance of O/W emulsions exhibited a significant decline from 2.54% to 0.12%. The NaCl concentration had a small effect on the stability of the emulsions. Molecular dynamics simulations revealed that HPAM adsorbed at the oil water interface by the point‐like nature, with stronger interaction between its amide group and the oil molecule than its carboxyl group. The hydrogen bond number and the hydrogen bond lifetime of HPAM‐H2O and HPAM‐HPAM increase with increasing the number of HPAM molecules at the oil‐water interface, slowing diffusion coefficient of water molecules and increasing the interface thickness. Increasing salinity can weaken the HPAM‐water interaction, reducing the emulsification stability. This work provides insights into the emulsification characteristics and mechanisms of HPAM. [ABSTRACT FROM AUTHOR]

Detailed quantum‐chemical calculations have been carried out to understand both the origin of the catalysis in the urea‐catalyzed nucleophilic ring‐opening of nitrocyclopropanes and the acceleration induced by the presence of an internal Lewis acid in the catalyst. To this end, the mode of activation of these ureas is quantitatively analyzed in detail by means of the Activation Strain Model of reactivity in combination with the Energy Decomposition Analysis method. It is found that the presence of the Lewis acid in the urea further enhances the interaction between the reactants, by increasing both the electrostatic and orbital attractions, which translates into a reduced activation barrier. This insight is also used to assess the impact of the nature of the Lewis acid on the transformation, facilitating the rational design of more active catalysts. [ABSTRACT FROM AUTHOR]

The creation of frustrated Lewis pairs on catalyst surface is an effective strategy for tuning CO2 activation. The critical step in the formation of frustrated Lewis pairs is the spatial effect of proximal Lewis acid‐Lewis base pairs. Here, we demonstrate a facile surface functionalization methodology that enables hydrogen bonding between N and H atoms to mediate the construction of frustrated Lewis pairs in poly(heptazine imide), thereby increasing the propensity to activate CO2 molecules. Experimental and theoretical results show that the construction of active hydrogen bonding regions can facilitate the bending of CO2 molecules. Furthermore, the delocalization of electron clouds induced by the hydrogen bonding‐mediated frustrated Lewis pairs can promote the heterolytic cleavage and photocatalytic conversion of CO2. This work highlights the potential of utilizing hydrogen bonding‐mediated strategy in heterogeneously photocatalytic activation of CO2 over polymer materials. [ABSTRACT FROM AUTHOR]

Polybenzimidazole (PBI) doped with phosphoric acid (PA) exhibits fast proton conduction in the range of 120–180 °C. However, PA loss during high temperature fuel cells (HT-PEMFCs) operation and plasticization after PA doping are the main obstacles to PBI membrane application. In this work, the properties of PA-doped PBI membranes were improved by branching polyurethane side chains onto the PBI backbone via N-substitution reaction. The urea and amide-ester bonds between the polyurethane side chains form a rich hydrogen bonding network. The hydrogen bonding network together with Ce–O coordination bonding enhance the mechanical properties of PBI membranes. Long branched chains increase the spacing between the molecular chains, and the additional unbonded groups in the polyurethane side chains can also form hydrogen bonding interactions with the PA, which increase the adsorption and retention capacity of the PA. The proton conductivity of polyurethane grafting PBI reached 0.104 S cm −1, while the conductivity of the pristine PBI membrane was only 0.026 S cm −1 under the same conditions. The PBI membrane grafted with polyurethane side chains showed a proton conductivity of up to 0.104 S cm −1 at 160 °C in anhydrous conditions, whereas the pristine PBI membrane showed a conductivity of only 0.026 S cm −1 under the same conditions. During single-cell testing, polyurethane-grafted PBI membrane peak power densities of 408 mW cm −2 could be achieved. In addition, the polyurethane grafted membrane has excellent durability with a voltage decay of only 245 μV h −1 in a 120 h test. Formation of a rich hydrogen bonding network in the polybenzimidazole membrane after grafting polyurethanes promotes rapid proton transfer. [Display omitted] • Rich hydrogen bonding network. • Ce-O coordination bonds enhance the mechanical properties of membranes. • Excellent durability. [ABSTRACT FROM AUTHOR]

2,4-Difluoronitrobenzene has been reacted with a linker diamine (ethylenediamine or propylenediamine) and butylamine, in either order, to give new molecular building blocks for porous supramolecular networks. Two structures were established by X-ray single crystal structure determinations. The propylenediamine structure displays small pores, which may be due to the longer and more flexible linker in the structure. [ABSTRACT FROM AUTHOR]

Motivated by the captivating allure of exquisitely regulated characteristics exhibited by 2‐(2‐hydroxyphenyl)‐benzoxazole and its derivatives in the domains of photochemistry and photophysics, our current endeavor primarily focuses on delving into the intricacies of photo‐induced excited state reactions for derivatives of 2,5‐bis(benzoxazol‐2‐yl)‐thiophene‐3,4‐diol (BTD). Given the profound impact of chalcogen element doping, our primary focus lies in investigating the excited state behaviors of BTD‐O, BTD‐S, and BTD‐Se fluorophores. Through simulations encompassing variations in geometry and vertical excitation charge reorganization, we unveil atomic‐electronegativity‐dependent hydrogen bonding interactions and photoexcitation‐induced charge recombination that can significantly augment the intramolecular double proton transfer (ESDPT) reaction in the excited state for BTD‐O, BTD‐S, and BTD‐Se fluorophores. By constructing potential energy surfaces and identifying transition state forms, we elucidate the ultrafast stepwise ESDPT mechanism facilitated by the low potential barriers. Moreover, we rigorously validate the chalcogen atomic electronegativity‐driven regulation of the stepwise ESDPT mechanism. We sincerely anticipate that manipulating solvent polarity will pave the way for groundbreaking advancements in luminescent materials. [ABSTRACT FROM AUTHOR]

Poly(acrylic acid) (PAAc) hydrogels are essential functional materials. However, their mechanical properties do not meet the required standards. In this study, a one‐pot method is employed to prepare cellulose‐reinforced PAAc hydrogels by dissolving allyl cellulose (AC) in acrylic acid (AAc) solutions. Fourier transform infrared (FTIR), solid‐state 13C nuclear magnetic resonance (NMR), and thermogravimetric (TG) analysis are used to demonstrate that the incorporation of AC results in the formation of covalent and hydrogen bonds, which contribute to the crosslink network of the PAAc hydrogels. Significantly, by modifying the ratio of AC to AAc in the pre‐polymerization solution, the prepared AC–PAAc hydrogels exhibit a transition from transparent to opaque. This suggests that phase separation is induced by hydrogen bonding. The occurrence of phase separation is verified by observing the hydrogel microstructures using scanning electron microscopy. Phase separation leads to enhanced polymer–polymer interactions in the hydrogels, resulting in a maximum fracture stress of 2.34 MPa. The AC–PAAc hydrogels display distinct swelling behavior under various pH conditions. Moreover, they demonstrate differences in transparency and mechanical properties when exposed to dimethyl sulfoxide (DMSO) and water, indicating their responsiveness to solvents. This work demonstrates the great potential of enhancing the mechanical performance and responsiveness of PAAc hydrogels. [ABSTRACT FROM AUTHOR]

Equilibrium dissociation energies De of the hydrogen‐bonded complexes HAl⋅⋅⋅HX and HGa⋅⋅⋅HX (X=F, Cl, Br, I, CN, CCH, and CP) were calculated ab initio at the CCSD(T)‐(F12c)/cc‐pVDZ−F12 level of theory. The gradients of graphs of De versus the electrophilicity EHX of the Lewis acids HX yielded the nucleophilicities NM−X of the Group 13 atoms M in these diatomic molecules. Molecular electrostatic surfaces potentials reveal that H−Al and H−Ga are bi‐nucleophilic and that the H ends of these H−M molecules are more nucleophilic than the M ends for M=Al and Ga, but not when M=boron. Therefore, the complexes M−H⋅⋅⋅HX were investigated using the same approach. It was concluded for M=Al and Ga that, for a given X, the M−H⋅⋅⋅HX complexes were more strongly bound than the corresponding H−M⋅⋅⋅HX complexes for both M=Al and Ga but the reverse order applies for M = boron. The effects of substituting the H atoms in the M−H molecules by F atoms and by methyl groups were investigated to measure the −I and +I inductive effects relative to H, respectively, on the nucleophilicities of the molecules M−H when M is acting as hydrogen‐bond acceptor in complexes H−M⋅⋅⋅H−X. [ABSTRACT FROM AUTHOR]

The excited‐state double proton transfer (ESDPT) reaction in the intermolecular hydrogen‐bonded complex 7‐azaindole:piperidin‐2‐one is investigated by quantum chemical calculations with particular emphasis on the H‐bonding interactions within the system. The natural bond orbital (NBO) calculations show that the X─H···Y H‐bonds in the studied complexes, namely, 7‐azaindole:piperidin‐2‐one (N‐form) and 7H‐pyrrolo[2,3‐b]pyridine:3,4,5,6‐tetrahydropyridin‐2‐ol (T‐form, proton transferred tautomer) are aptly described by nY→σ∗(X−H)${n}_{\mathrm{Y}} \to {\sigma }^*({{\mathrm{X}} - {\mathrm{H}}})$ hyperconjugative charge transfer effect (nY${n}_{\mathrm{Y}}$ is non‐bonded lone‐pair on Y‐atom). That the hyperconjugation effect outplays the rehybridization effect is invoked to account for the observed red‐shifting H‐bonds in harmony with the Bent's rule. The differential nature of interactions underlying the origin of X─H···Y H‐bonds in the complexes (N‐form and T‐form) is explored from atoms‐in‐molecules (AIM) calculations. The H‐bonds in the N‐form are found to have a primarily electrostatic origin (closed‐shell interaction) whereas the relatively stronger H‐bonds in the T‐form are assisted by contribution from shared‐shell (covalent) interaction. The nonoccurrence of the double‐proton transfer reaction in the S0 state is argued from the large barrier for the transformation N‐form → T‐form (N‐form constitutes the global minimum on the S0‐PEC), whereas the stability order is reversed together with a marked reduction of the energy barrier in the S1‐PEC accounting for the ESDPT process. [ABSTRACT FROM AUTHOR]

Three 2,4‐diarylpyrroles were synthesized starting from 4‐nitrobutanones and the crystal structures of two derivatives were analysed. These are 4‐(4‐methoxyphenyl)‐2‐(thiophen‐2‐yl)‐1H‐pyrrole, C15H13NOS, and 3‐(4‐bromophenyl)‐2‐nitroso‐5‐phenyl‐1H‐pyrrole, C16H11BrN2O. Although pyrroles without substituents at the α‐position with respect to the N atom are very air sensitive and tend to polymerize, we succeeded in growing an adequate crystal for X‐ray diffraction analysis. Further derivatization using sodium nitrite afforded a nitrosyl pyrrole derivative, which crystallized in the triclinic space group P with Z = 6. Thus, herein we report the first crystal structure of a nitrosyl pyrrole. Interestingly, the co‐operative hydrogen bonds in this NO‐substituted pyrrole lead to a trimeric structure with bifurcated halogen bonds at the ends, forming a two‐dimensional (2D) layer with interstitial voids having a radius of 5 Å, similar to some reported macrocyclic porphyrins. [ABSTRACT FROM AUTHOR]

The counterion-mediated hydrogen bonding (CMHB) is related to the hydrogen bonding between bound counterions and polyelectrolyte chains in polyelectrolyte systems, where the counterions can both electrostatically bind to the charged groups of polyelectrolyte chains and act as hydrogen bond donors or acceptors to form hydrogen bonds with the hydrogen bond sites associated with polyelectrolyte chains simultaneously. A large number of literatures illustrate that strong polyelectrolytes (SPs) are insensitive to pH, which severely limmits the applications of SPs as smart materials. However, our studies have demonstrated that the CMHB makes SPs pH-responsive. This perspective discusses the mechanism of pH responsiveness of SPs and the pH-tunable properties of SPs, based on the pH-controlled CMHB effect. The future research directions on the pH responsiveness of SPs are also discussed here. It is anticipated that the study of the pH responsiveness of SPs not only will provide a new understanding of the fundamental properties of SPs, but also will greatly expand the applications of SPs in the field of smart materials. [ABSTRACT FROM AUTHOR]