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Tuning of micro‐ and macro‐structures of hard carbon is important for expanding its properties. However, achieving controlled and integrated modulation of the micro‐ and macro‐structures of such materials remains a challenge. An intermolecular hydrogen bond‐driven interfacial cooperative‐assembly and then polymerization strategy is reported herein: micelles‐glucose molecules are used for the synthesis of wrinkled hard carbon spheres with precisely tunable crystallinity. As intermolecular hydrogen is positioned bonds to achieve an anchoring effect, which facilitates immobilization of glucose molecules at the molecular level during the assembly and subsequent dehydration‐aromatization. In virtue of controlling the micelle concentration, the density of intermolecular hydrogen bonding interactions is precisely regulated. As a result, the yielded hard carbon spheres exhibited excellent sodium‐ion storage performance because of their high crystallinity and exposed surfaces. By establishing a simple micelle–based interfacial reaction strategy, the study leverages optimized intermolecular hydrogen bond anchoring effects to tailor the properties of materials at a molecular level. [ABSTRACT FROM AUTHOR]

The molecular structure of the tripodal carbamoylmethylphosphine oxide compound diethyl {[(5-[2-(diethoxyphosphoryl)acetamido]-3-{2-[2-(diethoxyphosphoryl)acetamido]ethyl}pentyl)carbamoyl]methyl}phosphonate, C25H52N3O12P3, features six intramolecular hydrogen-bonding interactions. The phosphonate groups have key bond lengths ranging from 1.4696 (12) to 1.4729 (12) Å (P=O), 1.5681 (11) to 1.5811 (12) Å (P—O) and 1.7881 (16) to 1.7936 (16) Å (P—C). Each amide group adopts a nearly perfect trans geometry, and the geometry around each phophorus atom resembles a slightly distorted tetrahedron.

The molecular structure of the tripodal carbamoylmethylphosphine oxide compound diethyl {[(5-[2-(diethoxyphosphoryl)acetamido]-3-{2-[2-(diethoxyphosphoryl)acetamido]ethyl}pentyl)carbamoyl]methyl}phosphonate, C25H52N3O12P3, features six intramolecular hydrogen-bonding interactions. The phosphonate groups have key bond lengths ranging from 1.4696 (12) to 1.4729 (12) Å (P=O), 1.5681 (11) to 1.5811 (12) Å (P—O) and 1.7881 (16) to 1.7936 (16) Å (P—C). Each amide group adopts a nearly perfect trans geometry, and the geometry around each phophorus atom resembles a slightly distorted tetrahedron. [ABSTRACT FROM AUTHOR]

In the present research, thermal investigation of amorphous solid dispersions (ASDs) was performed in order to compare their relaxation transitions. Two different active pharmaceutical ingredients (APIs), namely naproxen (NAP) and spironolactone (SPIR), were used as model drugs and combined with polyvinylpyrrolidone vinyl acetate (PVPVA64) copolymer to form stable ASDs. The reason for the API selection was their different interacting potentials based on the presence (in the case of NAP) and the lack of H-bond donor group (in the case of SPIR). Determination of both Tg and sub-Tg transitions suggested that ASDs containing NAP and PVPVA64 are 'interacting' systems with respect to the H-bonding. Besides, temperature-dependent Raman spectroscopic experiments confirmed that the naphthalene ring of the NAP has a significant role in the sub-Tg relaxations. In contrast, SPIR-PVPVA64 systems proved to be 'non-interacting' ASDs according to the MDSC, TSDC, and Raman measurements. This study highlights that the combination of the results of different thermoanalytical investigations with spectroscopic methods helps to understand the molecular background of the relaxations in ASDs and thus contributes to the conscious design of stable amorphous pharmaceuticals in the early stage of development. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the microsolvation effect on proton exchange (PE) between carbonic acid and methylamine (CA-MTA) has been explored by quantum dynamics simulations. The structural, energy, and dynamic properties of the CA-MTA complex with and without an explicit water molecule are elucidated at the molecular level. The reactions from this study have been clarified into different types: single-step PE (SSPE) and stepwise PE (SWPE). Without the water molecule, the SSPE mechanism is hardly found but observable with a low probability of 0.2. In particular, the water molecule interacting through intermolecular hydrogen-bonded network between CA and MTA in CA-MTA-Win could affect PE by showing both SSPE and SWPE mechanisms. In addition, the existing water molecule plays the significant role in shortening intermolecular hydrogen bonding interactions within the complex resulting in increasing the probability of PE up to 0.92 especially in CA-MTA-Wout. Hence, one water molecule could be used to provide reliable results to represent the significant activity that occurs for the proton exchangeability of the CA and MTA complex.

Inspired by the concept of ionic charge‐transfer complexes for the Mott insulator, integer‐charge‐transfer (integer‐CT) cocrystals are designed for NIR photo‐thermal conversion (PTC). With amino‐styryl‐pyridinium dyes and F4TCNQ (7,7',8,8'‐Tetracyano‐2,3,5,6‐tetrafluoroquinodimethane) serving as donor/acceptor (D/A) units, integer‐CT cocrystals, including amorphous stacking "salt" and segregated stacking "ionic crystal", are synthesized by mechanochemistry and solution method, respectively. Surprisingly, the integer‐CT cocrystals are self‐assembled only through multiple D−A hydrogen bonds (C−H⋅⋅⋅X (X=N, F)). Strong charge‐transfer interactions in cocrystals contribute to the strong light‐harvesting ability at 200–1500 nm. Under 808 nm laser illumination, both the "salt" and "ionic crystal" display excellent PTC efficiency beneficial from ultrafast (∼2 ps) nonradiative decay of excited states. Thus integer‐CT cocrystals are potential candidates for rapid, efficient, and scalable PTC platforms. Especially amorphous "salt" with good photo/thermal stability is highly desirable in practical large‐scale solar‐harvesting/conversion applications in water environment. This work verifies the validity of the integer‐CT cocrystal strategy, and charts a promising path to synthesize amorphous PTC materials by mechanochemical method in one‐step. [ABSTRACT FROM AUTHOR]

Based on the marine natural products piperafizine B, XR334, and our previously reported compound 4m, fourteen novel 3,6-diunsaturated 2,5-diketopiperazine (2,5-DKP) derivatives (1, 2, 4–6, 8–16), together with two known ones (3 and 7), were designed and synthesized as anticancer agents against the A549 and Hela cell lines. The MTT assay results showed that the derivatives 6, 8–12, and 14 had moderate to good anticancer capacities, with IC50 values ranging from 0.7 to 8.9 μM. Among them, compound 11, with naphthalen-1-ylmethylene and 2-methoxybenzylidene functions at the 3 and 6 positions of 2,5-DKP ring, respectively, displayed good inhibitory activities toward both A549 (IC50 = 1.2 μM) and Hela (IC50 = 0.7 μM) cancer cells. It could also induce apoptosis and obviously block cell cycle progression in the G2/M phases in both cells at 1.0 μM. The electron-withdrawing functions might not be favorable for the derivatives with high anticancer activities. Additionally, compared to piperafizine B and XR334, these semi-N-alkylated derivatives have high liposolubilities (>1.0 mg mL−1). Compound 11 can be further developed, aiming at the discovery of a novel anticancer candidate. [ABSTRACT FROM AUTHOR]

A novel triazole fluorescent sensor was efficiently synthesized using binaphthol as the starting substrate with 85% total end product yield. This chiral fluorescence sensor was proved to have high specific enantioselectivity for lysine. The fluorescence intensity of R-1 was found to increase linearly when the equivalent amount of L-lysine (0–100 eq.) was gradually increased in the system. The fluorescence intensity of L-lysine to R-1 was significantly enhanced, accompanied by the red-shift of emission wavelength (389 nm to 411 nm), which was attributed to the enhanced electron transfer within the molecular structure, resulting in an ICT effect, while the fluorescence response of D-lysine showed a decreasing trend. The enantioselective fluorescence enhancement ratio for the maximum fluorescence intensity was 31.27 [ef = |(IL − I0)/(ID − I0)|, 20 eq. Lys], thus it can be seen that this fluorescent probe can be used to identify and distinguish between different configurations of lysine. [ABSTRACT FROM AUTHOR]

• The H 2 →N 3 process of 2,4-bImP in AcOH solvent is an intermolecular process. • Its intramolecular proton transfer process promotes second-step H 2 →N 3 process. • Explicit solvent induces fluorescence enhancement and wavelength blue shift. • Explicit solvent molecules have great influence on the ICT process of 2,4-bImP. The excited-state proton transfer process induces unique photophysical properties in organic molecules, which have been extensively applied in new optoelectronics, fluorescent dyes, photocatalysis, and other fields. Experimentally, a new organic molecule (2,4-bis(4,5-diphenyl-1H-imidazol-2-yl)phenol (2,4-bImP)) first synthesized with photochromic behavior triggered by the excited-state intramolecular proton transfer process. However, the specific theoretical details of the excited-state transfer process of this molecule were not provided. In this work, we utilized density functional theory and time-dependent density functional theory to investigate the influence of explicit solvent molecules on the excited-state double proton transfer process of this molecule. The results show that the formation of intermolecular hydrogen bonds between 2,4-bImP and two explicit solvent molecules can effectively reduce the energy barrier for excited-state double proton transfer. One molecule directly participates in the proton transfer process by establishing an intermolecular hydrogen bond bridge with the 2,4-bImP molecule, while the other molecule indirectly reduces the proton transfer energy barrier by weakening the electronegativity of the donor O atom of intramolecular hydrogen bond. This work allows us to realize the important role that explicit solvent molecules play in the proton transfer and photophysical properties of fluorescent molecules, and provides new insights and ideas for the development and design of novel fluorescent molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • NapH1 in DMF cannot undergo ESPT process in the presence of intermolecular hydrogen bond. • Due to differences on basicity and pKa values, NapH1 can form deprotonated form in S 0 state in DMF rather than in toluene. • The enol* and deprotonated* fluorescence combined to produce near-white-light in DMF. • The single fluorescence in toluene is originated from the original form. Organic white light materials fabricated on the basis of single molecules have applied to manufacture the white light-emitting diodes due to their good photostability and relatively simple material preparation. In this work, the different fluorescence emission mechanisms of the NapH1 in n,n-dimethylformamide (DMF) and toluene are investigated to elucidate the process for generating single-molecule near-white-light. From the analysis of bond lengths and electrostatic potential analysis, the intermolecular hydrogen bond can form in DMF instead of in toluene. From the potential energy curves, it is clear that intermolecular proton transfer is not feasible in either DMF or toluene. Frontier molecular orbitals analysis, the dissociation constants and the vertical excitation energies are used to confirm that NapH1 can undergo the deprotonation process in DMF rather than in toluene. Combined with the calculations of the fluorescence values, only the original structure exists stably in toluene which emits blue fluorescence. And the dual fluorescence peaks of NapH1 in DMF are originated from the enol form and the deprotonated form, interacting jointly to emit near-white light. This work contributes to the investigation and advancement for single-molecule organic white luminescent materials. [ABSTRACT FROM AUTHOR]

• Photophysical mechanism of NapH is clearly elucidated in H 2 O, MeOH and THF solvents. • The ESPT process is responsibility for the long-wavelength emission in H 2 O and MeOH. • The dual color fluorescence intensity is effectively regulated by the ESPT barrier. • Ideal white light emission mechanism is verified by mixing NapH1/NapH2 and DMSO/DIOX. Organic white light emitting (WLE) materials have sparked a research boom due to their promising applications in display devices, artificial lighting, and molecular sensors. However, the complex luminescence mechanism of full-spectra emitting materials has limited the development of white light materials with high stability and reproducibility. In this study, building on the full-spectra luminescent naphthimide dye (NapH) introduced by Xu et al., (Chin. Chem. Lett. 35(2024), 108348), we report the solvent-sensitive excited state proton transfer (ESPT) properties and white light emission mechanism in NapH. Our theoretical research results show that the ESPT process of NapH molecule is hindered in the low-polar solvent tetrahydrofuran (THF), so only the blue fluorescence from the Enol* is observed in the experiment. In contrast, in polar solvents such as water (H 2 O) and methanol (MeOH), the formation of strong intermolecular hydrogen bonds successfully initiates the ESPT process, leading to the dual fluorescence observed in experiments, with blue emission from the Enol* and red emission from the Nap anion. In essence, different solvent environments can adjust several emission colors. Furthermore, we theoretically verify that the optimal white light emission can be achieved when the mixed solvent ratio of dimethyl sulfoxide (DMSO) and dioxane (DIOX) is 5:5, which aligns well with experimental results. More importantly, we elucidate the specific WLE mechanism from multiple perspectives, including potential energy curves and electron spectra. Our work not only displays the interaction models of NapH molecule in various solvents, but also reveals the underlying luminescence mechanism, thus providing a valuable theoretical reference for the development and advancement of new white light materials. [ABSTRACT FROM AUTHOR]

Based on the marine natural products piperafizine B, XR334, and our previously reported compound 4m, fourteen novel 3,6-diunsaturated 2,5-diketopiperazine (2,5-DKP) derivatives (1, 2, 4–6, 8–16), together with two known ones (3 and 7), were designed and synthesized as anticancer agents against the A549 and Hela cell lines. The MTT assay results showed that the derivatives 6, 8–12, and 14 had moderate to good anticancer capacities, with IC50 values ranging from 0.7 to 8.9 μM. Among them, compound 11, with naphthalen-1-ylmethylene and 2-methoxybenzylidene functions at the 3 and 6 positions of 2,5-DKP ring, respectively, displayed good inhibitory activities toward both A549 (IC50 = 1.2 μM) and Hela (IC50 = 0.7 μM) cancer cells. It could also induce apoptosis and obviously block cell cycle progression in the G2/M phases in both cells at 1.0 μM. The electron-withdrawing functions might not be favorable for the derivatives with high anticancer activities. Additionally, compared to piperafizine B and XR334, these semi-N-alkylated derivatives have high liposolubilities (>1.0 mg mL−1). Compound 11 can be further developed, aiming at the discovery of a novel anticancer candidate.

Self-assembly of organic ions in aqueous solutions is a hot topic at the present time, and substances that are well-soluble in water are usually studied. In this work, aqueous solutions of sodium diclofenac are investigated, which, like most medicinal compounds, is poorly soluble in water. Classical MD modeling of an aqueous solution of diclofenac sodium showed equilibrium between the hydrated anion and the hydrated dimer of the diclofenac anion. The assignment and interpretation of the bands in the UV, NIR, and IR spectra are based on DFT calculations in the discrete-continuum approximation. It has been shown that the combined use of spectroscopic methods in various frequency ranges with classical MD simulations and DFT calculations provides valuable information on the association processes of medical compounds in aqueous solutions. Additionally, such a combined application of experimental and calculation methods allowed us to put forward a hypothesis about the mechanism of the effect of diclofenac sodium in high dilutions on a solution of diclofenac sodium. [ABSTRACT FROM AUTHOR]

Introduction. Biologically active compounds 4,6-dinitro-5,7-dichlorobenzofuroxan (4,6-DNDHBFO) and 5-nitro-4,6-dichlorobenzofuroxan (5-NDHBFO) effectively in-hibit ultra-resistant microorganisms: Staphylococcus aureus, pathogenic fungi – Aspergillius niger, Coniophora cerebella, Candida albicanas and other microor-ganisms. Mixed systems based on 4,6-DNDHBFO and 5-NDHBFO exhibit high potentiated synergistic activity against Aspergillius niger. Currently, there are no full-fledged studies about the mechanism of synergism of 5-NDHBFO and 4,6-DNDHBFO in a solidphase system. The results of the study of solid-phase sys-tems 5-NDHBFO – 4,6-DNDHBFO by IR spectroscopy will make it possible to establish the nature of the interaction between the components of the binary mix-ture.Aim. Experimental study of the intermolecular interaction of 5-NDHBFO with 4,6-DNDHBFO by the IR spectroscopy method.Materials and methods. The intermolecular interaction of 5-NDHBFO with 4,6-DNDHBFO at different ratios in a solid-phase system was studied by the IR spectroscopy method.Results and discussion. Based on the results of the study, the physico-chemical interaction of 5-NDHBPO with 4,6-DNDHBFO in solid-phase systems was revealed. Shifts and changes in the intensities of the characteristic frequencies of functional groups involved in the formation of intermolecular bonds between 5-NDHBPO and 4,6-DNDHBPO were revealed.Conclusion. The nature of the interaction between 4,6-DNDHBFO and 5-NDHBFO in the solid-phase system was established, leading to the appearance of a synergy effect. The interaction of 5-NDHBFO with 4,6-DNDHBFO in a bi-nary system is due to the formation of an intermolecular hydrogen bond. The in-teraction involves the proton of the 5-NDHBFO molecule, the oxygen of the fu-roxan ring of 4,6-DNDHBFO, as well as the halogen atom of 4,6-DNDHBFO at an equimolar ratio of the components of the solid-phase system.

A novel triazole fluorescent sensor was efficiently synthesized using binaphthol as the starting substrate with 85% total end product yield. This chiral fluorescence sensor was proved to have high specific enantioselectivity for lysine. The fluorescence intensity of R-1 was found to increase linearly when the equivalent amount of L-lysine (0–100 eq.) was gradually increased in the system. The fluorescence intensity of L-lysine to R-1 was significantly enhanced, accompanied by the red-shift of emission wavelength (389 nm to 411 nm), which was attributed to the enhanced electron transfer within the molecular structure, resulting in an ICT effect, while the fluorescence response of D-lysine showed a decreasing trend. The enantioselective fluorescence enhancement ratio for the maximum fluorescence intensity was 31.27 [ef = |(IL − I0)/(ID − I0)|, 20 eq. Lys], thus it can be seen that this fluorescent probe can be used to identify and distinguish between different configurations of lysine.

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Intermolecular hydrogen bonds are formed through the electrostatic attraction between the hydrogen nucleus on a strong polar bond and high electronegative atom with an unshared pair of electrons and a partial negative charge. It affects the physical and chemical properties of substances. Based on this, we presented a physical method to modulate intermolecular hydrogen bonds for not changing the physical–chemical properties of materials. The graphite and graphene are added into the glycerol, respectively, by being used as a viscosity reducer in this paper. The samples are characterized by Raman and 1H-nuclear magnetic resonance. Results show that intermolecular hydrogen bonds are adjusted by graphite or graphene. The rheology of glycerol is reduced to varying degrees. Transmission electron microscopes and computer simulation show that the spatial limiting action of graphite or graphene is the main cause of breaking the intermolecular hydrogen bond network structure. We hope this work reveals the potential interplay between nanomaterials and hydroxyl liquids, which will contribute to the field of solid–liquid coupling lubrication.

• Densities and excess volumes for propylene glycol methyl ether + 1,2-propylenediamine. • Viscosities and viscosity deviation for propylene glycol methyl ether + 1,2-propylenediamine. • Form of HBs as OH···NH 2 in propylene glycol methyl ether + 1,2-propylenediamine. In this work, the systematic measurements of physicochemical properties, viz., density (ρ) and viscosity (η) values of propylene glycol methyl ether (PGME) + 1,2-propylenediamine (1,2-PDA) binary system, including pure substances, over the entire mole fraction range at the temperatures of T/K = (298.15 to 318.15) under atmospheric pressure of P = 100.5 kPa. The fundamental data were used to calculate several excess properties, including excess molar volume (V m E), viscosity deviation (Δ η), and excess activation Gibbs free energy (Δ G ∗ E). Meanwhile, the work further investigated the values of thermal expansion coefficient (α p), partial molar volume ( V ¯ ) and apparent molar volume (V φ), thereby offering a comprehensive understanding on non-ideal behavior of the binary system. Furthermore, the variations in ρ values with various molar ratios and temperatures were evaluated through Jouyban-Acree model and nonlinear least squares method. Simultaneously, Grunberg-Nissan model, Eyring-Margules model, Heric model, and McAllister model, were used to fit the dependence of η values on the molar ratio. Arrhenius equation was employed to fit the temperature dependency of η values. In addition, Redlich-Kister (R-K) equation was utilized to fit the V m E , Δ η , and Δ G ∗ E values of binary system. Based on spectral analyses of Raman, ultra-violet (UV), and 1H Nuclear Magnetic Resonance (NMR) and density functional theory (DFT) calculation, the intermolecular hydrogen bond (IHB) of PGME with 1,2-PDA was discussed in depth. [ABSTRACT FROM AUTHOR]

The inclusion of catechins with cyclodextrin (CD) is performed for the purpose of improving the water solubility and reducing the bitterness of catechins. In this study, the effect of catechins' conformation on the formation of an inclusion complex between catechins and β-CD was examined by density functional theory (DFT) calculation at the B3PW91/cc-pVDZ level. It is known that the main components of catechins in tea leaves are (−)-epigallocatechin (EGC), which is a non-gallate-type catechin, and (−)-epigallocatechin gallate (EGCg), which is a gallate-type catechin. Catechins have a plurality of sites that can be included by β-CD (EGC: AC ring and B ring, EGCg: AC ring, B ring, and B′ ring). First, initial models for the calculation in which each ring of catechins gradually approaches into the cavity of β-CD were built. These initial models were optimized in water and then the optimized structure of the inclusion complex in water was determined. From the results of calculation, the degree of penetration of each ring into the β-CD cavity, the complex formation energy, and the number of intermolecular hydrogen bonds were examined. The results of calculation showed that the AC ring of catechins is most deeply included in the β-CD cavity and the B′ ring of catechins forms an energetically stable complex with β-CD. It was found that the inclusion complex of catechins and β-CD is stabilized energetically by intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Self-assembly of organic ions in aqueous solutions is a hot topic at the present time, and substances that are well-soluble in water are usually studied. In this work, aqueous solutions of sodium diclofenac are investigated, which, like most medicinal compounds, is poorly soluble in water. Classical MD modeling of an aqueous solution of diclofenac sodium showed equilibrium between the hydrated anion and the hydrated dimer of the diclofenac anion. The assignment and interpretation of the bands in the UV, NIR, and IR spectra are based on DFT calculations in the discrete-continuum approximation. It has been shown that the combined use of spectroscopic methods in various frequency ranges with classical MD simulations and DFT calculations provides valuable information on the association processes of medical compounds in aqueous solutions. Additionally, such a combined application of experimental and calculation methods allowed us to put forward a hypothesis about the mechanism of the effect of diclofenac sodium in high dilutions on a solution of diclofenac sodium.

The title hemihydrate, C12H9N5·0.5H2O, was isolated from the condensation reaction of quinoline-2-carbaldehyde with 4-amino-4H-1,2,4-triazole. The Schiff base molecule adopts an E configuration about the C=N bond and is approximately planar, with a dihedral angle between the quinoline ring system and the 1,2,4-triazole ring of 12.2 (1)°. In the crystal, one water molecule bridges two Schiff base molecules via O—H...N hydrogen bonds. The Schiff base molecules are interconnected by π–π stacking interactions [centroid-centroid distances of 3.7486 (7) and 3.9003 (7) Å] into columns along [1\overline{1}0].

Solubility data were determined using a laboratory scale reaction kettle for dilute SO2 in 2-Butoxy ethanol (BOE) (1) + water (H2O) (2) binary system at a temperature range of 298.15–308.15 K under 123.15 kPa. Based on solubility data, the linear slope of the solubility was fitted with Henry's law, and the SO2 solubility in BOE (1) + H2O (2) binary system showed a minimum at 40 wt%. The regeneration results showed that the SO2 absorption process was reversible in the binary system, and the system could be reused and almost no solvent loss after five cycles. Additionally, the spectral data indicated that the hydrogen bonds among BOE, H2O, and molecular SO2 contribute to the solubility of SO2. [ABSTRACT FROM AUTHOR]

The surface chemistry of catalyst plays a vital role in the catalytic process. And the effects of surface groups of porous boron nitride (p -BN) on the hydrogenation reaction have not been studied in detailed. In this work, two main surface species of Co/ p -BN catalyst were tuned thermally and their roles on the hydrogenation reaction were discriminated by α, β-unsaturated aldehyde hydrogenation reaction. The surface B O content decreased at higher reduction temperature and the cobalt phase changed from CoO to the mixture of CoO and Co0. The Co/ p -BN-500 exhibited the highest selectivity to C O hydrogenation. And its turnover frequency (TOF) of 13.2 h−1 is close to the optimal value of reported cobalt catalysts. When the reaction proceeds, hydrogenation rate of C O increases but that of C C decreases gradually, thus a surface groups variation was expected at the initial period. Further in-situ FTIR spectra showed the band intensity of edge N H increases as the adsorption proceeds at 50°С but it decreases as the temperature rise to 200°С, in combined with the shift of C O adsorption peak, a intermolecular hydrogen bond between edge N H and the terminal C O group was suggested, which account for the better selectivity to C O than C C. Unlabelled Image • The surface B O and N H of boron nitride is regulated by controlling reduction temperature. • The Co/ p -BN-T catalysts exhibit huge difference on activity of cinnamaldehyde hydrogenation. • The intermolecular hydrogen bond between N H and C O facilitates the selectivity to cinnamyl alcohol. [ABSTRACT FROM AUTHOR]

Abstract We report the influence of intermolecular and intramolecular hydrogen bonding on the excited state proton transfer (ESPT) emission behavior of two bent core liquid crystal (BLC) molecules, C 54 H 63 NO 9 (BLC3) and C 60 H 75 NO 9 (BLC4), having a Schiff-base and two long alkyl chains at its two ends. Fluorescence spectra of these BLC molecules dispersed in different solvents show dual emission (at ∼ 365 nm and ∼425 nm) from the keto and enol tautomers. We observed that the population of these keto and enol tautomers and the corresponding intensities of fluorescence emission are strongly influenced by the solvent polarity. In protic solvents, formation of intermolecular hydrogen bond with the Schiff-base of the BLC molecules is highly favoured than the intramolecular hydrogen bonding. This intermolecular hydrogen bonding drastically reduces the population of the keto tautomers in the excited state, resulting in enhanced enol fluoroscence band along with a weak keto emission band. The observed intensity of the enol fluorescence band is the highest for the most studied polar solvent (methanol). On the other hand, in aprotic solvents, the intramolecular hydrogen bonding is highly favoured, which leads to the formation of keto tautomers in the excited state. Hence, an intense keto emission band is observed for the aprotic solvents along with a weak enol emission band. From the time resolved fluorescence studies we observed a longer life time for the keto band than that for the enol band. This is also related to the delayed emission associated with the vibrational bands resulting from the bulky alkyl chains attached to the ends of the BLC molecules. Graphical abstract The intensity of fluoroscence emission can be tuned through solvent polarity via formation of intramolecular or intermolecular hydrogen bonds. Image 1 Highlights • Excited State Proton Transfer emission of the LCs can be tuned through the solvent polarity. • Intensity of keto emission increases with increase in polarity of the protic solvents. • Intra-molecular (inter-molecular) hydrogen bonds prevail in aprotic (protic) solvents. • The intensity of keto - (enol-) emission is stronger in aprotic (protic) solvents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Water molecules can be used as hydrogen bond bridges to produces a synergistic excited intermolecular double-proton transfer process, which effectively reduces the ESIPT barrier. • The drastically increased water fraction in the solvent inhibits the ESIPT reaction. • The phenomenon of fluorescence quenching can be ascribed to the increased polarity of solvent and stimulative ICT process. • Our work provides a theoretical basis for the synthesis of new Schiff base fluorescent chromophores for the water detection in organic solvents. The 8-hydroxyquinoline-2-carboxaldehyde thiosemicarbazone (HQCT) is sensitive to water molecules in dimethyl sulfoxide according to the experimental phenomenon description, with a sensory performance that is dependent on the water-based hydrogen bond bridge as mediator. Here the excited state intramolecular (ESAPT) and intermolecular (ESEPT) proton transfer mechanism involved by water solvent and the optical properties associated with them are clarified in details. Along the minimum energy pathways in the scanned potential energy surfaces (PESs), we find that the ESEPT reaction induced by water molecule is a synergistic double-proton transfer process. And the results indicate that trace water molecules can promote the reaction effectively. In addition, we also investigate the photophysical properties involved with the excited state proton transfer (ESPT) reaction with the increase of water fraction in the solvent. The results show that the fluorescent oscillator strength (f) and radiative rates (k r) decrease with the increase of water fraction, which are consistent with the experimental phenomenon. We attribute the phenomenon of fluorescence quenching to the increasing transition dipole moment (μ) which accelerates the intramolecular charge transfer (ICT) process. Our work not only explain the water-detection mechanism in the organic solvent before water-sensitive reactions essentially, but also provide a theoretical basis for the synthesis of new Schiff base fluorescent chromophores for the water detection in organic solvents. [ABSTRACT FROM AUTHOR]

[Display omitted] • ESIPT process of compound 1a is completed through DMSO molecular bridge assisted. • Infrared vibrational spectrum and electrostatic potential demonstrate tendency of intermediate formation. • The potential energy curves prove origin of three fluorescence peaks. • The attribution of triple fluorescence peaks was revised. The compound in solvents with triple fluorescence feature of excited state intramolecular proton transfer (ESIPT) has a broad prospect in fluorescent probes, dye sensors and molecular synthesis of photosensitive dyes. An ESIPT molecule hydroxy-bis-2,5-disubstituted-1,3,4-oxadiazoles (compound 1a) emits two fluorescence peaks in dichloromethane (DCM) and three fluorescence peaks in dimethyl sulfoxide (DMSO). [Dyes and Pigments 197 (2022) 109927]. Two longer peaks were attributed to enol and keto emission in both solvents and the shortest third peak in DMSO was just attributed simply. However, there is a significant difference in proton affinity between DCM and DMSO solvents which has influence on the position of emission peaks. Therefore, the correctness of this conclusion needs to be further verified. In this research, density functional theory and time-dependent density functional theory method are used to explore ESIPT process. Optimized structures indicate ESIPT occurs through molecular bridge assisted by DMSO. The calculated fluorescence spectra demonstrate two peaks indeed originated from enol and keto in DCM, while interestingly three peaks are originated from enol, keto and intermediate in DMSO. Infrared spectrum, electrostatic potential and potential energy curves further prove existence of three structures. We reveal the mechanisms that compound 1a molecule occurs ESIPT in DCM solvent and undergoes an ESIPT through assisted by DMSO molecular bridge. Additionally, three fluorescence peaks in DMSO are reattributed. Our work is expected to provide an insight for understanding intra- and intermolecular interactions and synthesis of efficient organic lighting-emitting molecule. [ABSTRACT FROM AUTHOR]

• To report densities and excess volumes for n-propanol/isopropanol and EDA. • Two n-propanol/isopropanol binding one EDA to form stable hydrogen bonds. • To report viscosities and viscosity deviation for n-propanol/isopropanol and EDA. • To confirm hydrogen bonds as –OH···NH 2 – from spectra and computational chemistry. Density (ρ) and viscosity (η) values of binary mixtures composed of n-propanol/isopropanol and ethylenediamine (EDA) were measured at T = (298.15–318.15) K and P = 1005 hPa (atmospheric pressure in Tianjin, China). The excess properties, including viscosity deviation (Δη), excess molar volume (V m E), and excess Gibbs energy of activation of viscous flow (ΔG*E), were then obtained. The least-squares method and Jouyban–Acree model were used to correlate the experimental ρ values and kinematic viscosity associated with three semi-empirical models, and a superior fitting was obtained by comparing the model parameters. V m E , Δη, and ΔG*E were fitted to the Redlich–Kister equation, and partial molar volumes, apparent molar volumes, and viscous activation parameters of n-propanol/isopropanol and EDA binary mixtures were calculated. Raman spectroscopy, fluorescence spectroscopy (FLS), 1H NMR spectroscopy, and computational chemistry methods were used to demonstrate the existence of intermolecular hydrogen bonds (IHBs) in n-propanol/isopropanol and EDA binary mixtures, and the form of IHBs was confirmed as –OH···NH 2 –. Finally, the CO 2 uptake rate was measured for binary mixtures at the molar fractions with strong intermolecular interactions. [ABSTRACT FROM AUTHOR]

Abstract: Metallosupramolecule‐based polymeric platforms with high degrees of hierarchy and tailorable functionalities are of great interests because of their unique morphologies and potential applications. Herein, the controllable synthesis of a highly‐ordered polymeric structure, {[M,P‐Co8(PDA)6(HIP)3(DMF)5(H2O)]3‐[Co(DMF)(H2O)2]} (1) (PDA=2,6‐pyridinedicarboxylate, HIP=5‐hydroxyisophthalate, DMF=dimethylformamide) with unique topology is reported. The solid‐state structure of 1 reveals that it is alternately and periodically assembled from racemic supramolecular monomers to form a zigzag‐shaped polymeric strand. Discrete racemic supramolecules (2) with topologies similar to those of monomeric species of 1 are also controllably synthesized in a separate reaction. Formation of intermolecular hydrogen bonds between supramolecules associated with hydroxyl groups of HIPs are critical for the unique solid‐state packing geometries of 1 and 2. [ABSTRACT FROM AUTHOR]

The control of internal molecular motions by outside stimuli is a decisive task in the construction of functional molecules and molecular machines. Light-induced intramolecular rotations of photoswitches have attracted increasing research interests because of the high stability and high reversibility of photoswitches. Recently, Henry et al. reported an unprecedented two-dimensional controlled photoswitch, the hemithioindigo (HTI) derivative Z1, whose single bond rotation in dimethyl sulphoxide (DMSO) solvent and double bond rotation in cyclohexane solvent can be induced by visible light (J. Am. Chem. Soc. 2016, 138, 12,219). Here we investigate the intramolecular rotations of the HTI and Z1 in different polar solvents by time-dependent density functional theory (TDDFT) and Nonadiabatic dynamic simulations. Due to the steric hindrance between methyl and thioindigo fragment, the rotations of Z1 in the excited state are obstructed. Interestingly, the HTI exhibits two distinct rotation paths in DMSO and cyclohexane solvents at about 50 fs. The intermolecular hydrogen bonds between HTI and DMSO play an important role in the rotation of HTI in DMSO solvent. Therefore, the HTI is a more promising two-dimensional photoswitch compared with the Z1. Our finding is thus of fundamental importance to understand the mechanisms of this class of photoswitches and design complex molecular behavior. [ABSTRACT FROM AUTHOR]

Density functional theory and time-dependent density functional theory methods were carried out to investigate the excited-state intramolecular charge transfer process (ICT) of coumarin 340 (C340) in tetrahydrofuran (THF) solvent for the first time. The plotted electrostatic potential and optimized geometric structures vividly indicated that the intermolecular hydrogen bond can be formed between the N-H group of C340 monomer and the oxygen atom of THF solvent. The analysis of frontier molecular orbitals and the differences in electronegativity confirmed the occurrence of ICT process in hydrogen-bonded complex C340-THF upon photoexcitation. The results of calculated bond lengths and bond energies revealed that the intermolecular hydrogen bond in C340-THF is significantly strengthened in the first excited state. Furthermore, the calculated electronic spectra, non-covalent interactions and IR spectra provided strong evidence for the hydrogen bond reinforce. Based on the theoretical calculations, we demonstrated that the ICT process in C340-THF can be facilitated effectively by the excited-state intermolecular hydrogen bond strengthening. [ABSTRACT FROM AUTHOR]

In this work, based on density functional theory (DFT) and time‐dependent DFT (TD‐DFT) methods, we theoretically investigate the excited‐state process of the 2‐(6'‐hydroxy‐2'‐pyridyl)benzimidazole (2HPB) system in acetonitrile and water solvents. Since acetonitrile is an aprotic solvent, it has no effect on the solvent‐assisted excited‐state proton transfer (ESPT) process. Therefore, the 2HPB molecule cannot transfer the proton in acetonitrile, which is consistent with previous experimental observation. On the other hand, 2HPB can combine one water molecule (which is a protic solvent), forming the 2HPB–H2O complex in the S0 state. After photoexcitation, the intermolecular hydrogen bonds O1H2···O3 and O3H4···N5 both get strengthened in the S1 state, which leads to the possibility of a water‐assisted ESPT process. Further, the charge redistribution reveals the tendency of ESPT. By exploring the potential energy curves for the 2HPB–H2O complex in water, we confirm that a stepwise double proton transfer process occurs in the S1 state. Water‐assisted ESIPT can occur along O1H2···O3 or O3H4···N5 because of their similar potential barriers. Based on the stepwise ESPT mechanism, we reinterpret the absorption and fluorescence spectra mentioned in the experiments and confirm the rationality of the water‐assisted ESPT process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The inter-PT process of the pheomelanin building block in methanol is reconsidered. • The single fluorescence peak is ascribed to the enol* form emission. • The competition of TICT state and the reduced charge coupling are the prime reasons for the non-fluorescence of keto* form. Pheomelanin is responsible for enhancing UV sensitivity and its proton transfer (PT) process is crucial to reveal the complex mechanisms of pheomelanin phototoxicity. Nahhas et al. studied the PT process of the pheomelanin building block 6-(2-amino-2-carboxyethyl)-4-hydroxy-1,3-benzothiazole (BT) in methanol. Based on the small Stokes shift corresponding to the absorption and fluorescence peaks, it is deemed that BT cannot perform PT process in methanol [J. Phys. Chem. Lett. 5 (2014) 2094–2100]. However, protic methanol solvent has both oxygen atom that attract proton and hydrogen atom that supply proton. It is worth reconsidering about the intermolecular proton transfer (inter-PT) process of BT with the aid of methanol. In our work, the inter-PT process of BT and methanol molecules are deciphered by density functional theory and time-dependent density functional theory. The structures, non-covalent interactions and infrared spectra testify that the double hydrogen bonds are reinforced under photoexcitation. The potential energy curve of S 1 state without barrier attests that the inter-PT process can occur in the BT molecule where methanol acts as the proton transporter. In addition, the fluorescence of BT-methanol complex is emitted by enol* form. In the light of the frontier molecular orbitals, the non-fluorescence of keto* form is explained by the reduced charge coupling compared to the enol* form and the competition of the twisted intramolecular charge transfer state. Our results provide an insight for understanding the photochemical process of the pheomelanin in protic systems. [ABSTRACT FROM AUTHOR]

"D-A pairs" as the basic "micro-stacking units" in cocrystals guarantee strong donor-acceptor interactions and excellent photothermal performance. Dynamics of excited states, mechanochemistry, integer-charge-transfer, intermolecular hydrogen bond, photo-thermal conversion Keywords: dynamics of excited states; mechanochemistry; integer-charge-transfer; intermolecular hydrogen bond; photo-thermal conversion EN dynamics of excited states mechanochemistry integer-charge-transfer intermolecular hydrogen bond photo-thermal conversion 1 1 1 07/25/23 20230721 NES 230721 B The Front Cover b shows integer-charge-transfer cocrystals are self-assembled via multiple intermolecular hydrogen bonds with one electron transferred from donor to acceptor unit for high-efficiency (~87 %) NIR photothermal conversion. [Extracted from the article]

• To report densities and excess volumes for 1,2-propanediamine with two mono-alcohols. • Two n-propanol/isopropanol binding one 1,2-propanediamine to form stable hydrogen bonds. • To report viscosities and viscosity deviation for 1,2-propanediamine with two mono-alcohols. • To confirm hydrogen bonds as –OH···NH 2 – from spectra and computational chemistry. To understand excess properties and intermolecular interactions of 1,2-propanediamine and n-propanol/isopropanol binary mixtures, their density and viscosity were systemically measured at T = (298.15–318.15) K under atmospheric pressure (1005 hectopascals in Tianjin, China), and their excess molar volume (V m E), viscosity deviation (Δ η) and excess viscous activation free energy (ΔG*E) were also calculated. From the results of V m E , it can be inferred that two n-propanol/isopropanol molecules and one 1,2-propanediamine molecule have the strongest binding capacity and form the most stable intermolecular hydrogen bonds. The experimental density and kinematic viscosity were correlated and predicted by several semi-empirical models, among which the Jouyban-Acree model had a better fit for the density and the McAllister four-body equation had a better fit for the kinematic viscosity, and the calculated results of V m E , Δη and ΔG*E were analyzed using the R-K equation. Meanwhile, the apparent molar volume, partial molar volume, thermal expansion coefficient and viscous activation parameters of 1,2-propanediamine and n-propanol/isopropanol solutions were calculated and analyzed. After that, the existence of intermolecular hydrogen bonds (IHBs) between 1,2-propanediamine and n-propanol/isopropanol binary mixtures was demonstrated on the basis of computational chemistry. And then, the IHBs between 1,2-propanediamine and n-propanol/isopropanol binary mixtures with the form of –OH···NH 2 – were further confirmed based on Raman, ultraviolet (UV), fluorescence (FLS) and nuclear magnetic resonance (1H NMR) spectral technologies. [ABSTRACT FROM AUTHOR]

Boronic acids and boronates are known as redox shuttles and film-forming additives. For example, 3,5-bis(trifluoromethyl)phenylboronic acid is reduced at a higher potential than that of PC-solvated $$\hbox {Li}^{+}$$ ion because of its lower LUMO energy level. Theoretical (molecular modelling) studies of the HOMO and LUMO energies of several phenylboronic acids and -boronates showed that the LUMO energies of all boronates were significantly lower than the LUMO energies of the commonly used carbonate electrolytes, both in vacuo and in solution, making them good candidates as electrolyte additives. The preferred conformation in vacuo and in solution of the boronate ester groups was 'in-out', with dihedral angles between the aromatic ring and boronate group varying between $$29.5{^{\circ }}$$ and $$33.6{^{\circ }}$$ . In contrast, the preferred conformations of the phenylboronic acids were found to be always coplanar and 'out-out', with dihedral angles close to $$0{^{\circ }}$$ . We speculated that back-bonding and intermolecular hydrogen bonding played a role. In this study, therefore, we investigated the role of intermolecular hydrogen bonding and solvation in this phenomenon, using HF and DFT methods. [ABSTRACT FROM AUTHOR]

A new energetic co-crystal consisting of one of the most powerful explosive molecules 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and the military explosive cyclotrimethylenetrinitramine (RDX) was prepared with a simple solvent evaporation method. Scanning electron microscopy (SEM) revealed the morphology of the bar-shaped product, which differed greatly from the morphology of the individual components. Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction spectrum (XRD), and differential scanning calorimetry (DSC) proved the formation of the co-crystal at the molecular level. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to raw CL-20. Finally, a possible crystallization mechanism was discussed. [ABSTRACT FROM AUTHOR]

The co-adsorption of CO and H 2 O on a Co(0001) surface at 100 K has been systematically studied using temperature programmed desorption (TPD) and density functional theory (DFT) calculations. While the TPD spectra of CO is almost not affected by the presence of H 2 O, the stabilization of H 2 O by co-adsorbed CO is found for the first time in a large coverage range (0.15 ML < θ CO < 0.66 ML; 0.01 ML < θ H2O < 0.6 ML). When the coverage of predosed CO is lower than 0.27 ML, the formerly single desorption peak of H 2 O is gradually separated into three peaks at 0.6 ML coverage. Those at lower and higher temperatures may be attributed to the repulsive interaction between H 2 O molecules and the attractive interaction between H 2 O and CO molecules, respectively. With increasing the coverage of predosed CO, not only the position of the high temperature peak shifts toward higher temperature (by about 15 K), but the intensity is greatly strengthened until a maximum is achieved when θ CO = 0.36 ML. DFT calculations suggest that the attractive interaction between H 2 O and CO on Co(0001) originates from the formation of intermolecular hydrogen bonds. This work not only provides insights into water gas shift reactions with H 2 O and CO as reactants, but opens new avenues for a volume of catalytic process of technological importance. [ABSTRACT FROM AUTHOR]

An energetic co-crystal consisting of the most promising military explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and the most well-known oxidant applied in propellants ammonium perchlorate has been prepared with a simple solvent evaporation method. Scanning electron microscopy revealed that the morphology of co-crystal differs greatly from each component. The X-ray diffraction spectrum, FTIR, Raman spectra, and differential scanning calorimetry characterisation further prove the formation of the co-crystal. The result of determination of hygroscopic rate indicated the hygroscopicity was effectively reduced. At last, the crystallisation mechanism has been discussed. [ABSTRACT FROM AUTHOR]

Nano-sized energetic co-crystal consisting of the most powerful used military explosive 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and a typical insensitive explosive used in propellants nitroguanidine (NQ) was prepared by vacuum freeze drying method. Material studio 6.1 was used to simulate the hydrogen bonds between CL-20 and NQ molecules. Scanning electron microscopy (SEM) was used to reveal the morphology and size of the product. Fourier Transform infrared spectroscopy (FT-IR) and X-ray diffraction spectrum (XRD) proved the formation of the co-crystal at the molecular level. Differential scanning calorimetry (DSC) was employed to characterize the thermal behavior of the co-crystal. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to neat CL-20. [ABSTRACT FROM AUTHOR]

Rheological properties of micellar solutions of a cationic Gemini surfactant, 2-hydroxypropyl-1,3-bis (dodecyldimethylammonium chloride), are studied as a function of aging time and salt addition. The results show that the self-aggregating behaviour in solution changes as a factor of time, probably due to intermolecular hydrogen bonds. The viscosity of the solution undergoes a series of visible changes so that the solution changes from a flow state to highly viscoelastic state, and finally, to a transparent solid, with a corresponding 4–6-fold increase in zero shear state viscosity. Rheology and freeze fracture transmission electron microscopy (FF-TEM) measurements show rod-like micelles at the beginning, which then change to wormlike micelles, and eventually to a quasi-gel-like network. Addition of an inorganic salt (NaCl) induces salting out, while the addition of an organic salt (NaSal) promotes micellar growth. At a fixed NaSal-to-surfactant molar ratio of 3:5, all solutions show Maxwell fluid behaviour and maximum zero-shear-rate viscosity; these trends can be attributed to the formation of a network structure between the cationic ions of the surfactant and Sal–as the surfactant concentration increases. Crystal analysis further confirms the presence of structures linked by intermolecular hydrogen bonds. [ABSTRACT FROM PUBLISHER]

Quantum mechanical calculations on geometries and vibrational wavenumbers of 4,4′-diethyl-2,2′-[methylazanediylbis(methylene)]diphenol denoted as EMD were performed by density functional theory (DFT/B3LYP) methods with the various basis sets, namely, 6-311G(d), 6-311G(d,p) and 6-311 + G(d,p). X-ray crystal structure of the EMD compound was measured at low temperature (100 K) and room temperature (296 K). It was found that no structural change was observed for the temperatures studied. The geometrical parameters from theoretical calculation were in good agreement with the ones from X-ray analysis. Both the theoretical and experimental structures confirmed the presence of the remarkably asymmetric intramolecular hydrogen bonding within the molecule of the EMD compound. Conformational analysis was carried out to calculate energy barrier of breaking the intramolecular hydrogen bond. Moreover, the theoretical IR and Raman spectra have been constructed to make a comparative study with the experimental FT-IR and FT-Raman spectra. The results revealed that the deviation of the theoretical wavenumbers from the experimental values were very small. Besides, the detailed vibrational assignments were conducted and the PED values were reported by VEDA4f program. [ABSTRACT FROM AUTHOR]