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Oriented ligand immobilization is one of the most effective strategies used in the design and construction of a high-capacity protein A chromatography. In this work, cysteine was introduced as anchoring sites by substituting a specific residue on Helix I, II, and at C-terminus of antibody binding domain Z from protein A, respectively, to investigate structural evolution and binding behavior of protein A ligands at liquid-solid interfaces. Among the three affinity dextran-coated Fe3O4 magnetic nanoparticles (Fe3O4@Dx MNPs), affinity MNPs with the immobilized ligand via N11C on Helix I (Fe3O4@Dx-Z1 MNPs) had the highest helical content, and MNPs with the immobilized ligand via G29C on Helix II (Fe3O4@Dx-Z2 MNPs) had the lowest helical content at the same pHs. It was attributed to less electrostatic attraction of ligand to negatively charged surface on Fe3O4@Dx-Z1 MNPs because of less positive charged residues on Helix I (K6) than Helix II (R27/K35). Among the three affinity MNPs, moreover, the highest affinity to immunoglobulin G (IgG) binding was observed on Fe3O4@Dx-Z1 MNPs in isothermal titration calorimetry measurement, further validating greater structural integrity of the ligand on Fe3O4@Dx-Z1 MNPs. Finally, the study of IgG binding on MNPs and 96-well plates showed that anchoring sites for ligand immobilization had distinct influences on IgG binding and IgG-mediated antigen binding. This work illustrated that anchoring sites of the ligands had a striking significance for the molecular structure of the ligand at liquid-solid interfaces and raised an important implication for the design and optimization of protein A chromatography and protein A-based immunoassay analysis.

The recent discoveries of many metal superhydrides provide a new route to room-temperature superconductors. However, their stability and structure trends and the large chemical driving force needed to dissociate H2 molecules and form H covalent network cannot be explained by direct metal-hydrogen bonds and volume effect. Here, we demonstrate that the understanding of superhydrides formation needs a perspective beyond traditional chemical bond theory. Using high-throughput calculations, we show that, after removing H atoms, the remaining metal lattices exhibit large electron localization at the interstitial regions, which matches excellently to the H lattice like a template. Furthermore, H lattices consist of 3D aromatic building units that are greatly stabilized by chemical templates of metals close to s-d border. The chemical template theory can naturally explain the stability and structure trends of superhydrides and help to predict new materials such as two-metal superhydrides.

Photoluminescent materials play an essential part in the application of polymer systems. However, intrinsic polymer systems have rarely been intuitively interpreted based on photoluminescent regula...

The unveiling of MOF growth mechanism is hampered by the lack of fundamental knowledge about the very early stage of nucleation, especially the form and ratio of molecular species in the solution for crystal growth. Herein, we report the detection of growth species for a series of MOFs with mono-linker, Cu-MOF-2-BDC and Cu-MOF-2-NDC, and two linkers, MTV-MOF-2-(C4H4)x, by high resolution ESI-MS, where a large variety of Cu-containing species are identified unambiguously. The solvent molecules such as H2O, methanol and DMF participate in the formation of these species, other than ethanol. Furthermore, in the growth solution of MTV-MOF-2-(C4H4)x, growth species containing two different organic linkers are observed. The feeding ratio is not the only factor controlling the distribution of growth species for MTV-MOFs, but also the solvent involves in coordination, an aspect usually overlooked previously.

Propylene molecule owns two active sites, the direct epoxidation of propylene by dioxygen is still a challenge due to the limitation of selectivity. In this work, the direct liquid-phase propylene aerobic epoxidation protocol by chloride manganese meso-tetraphenylporphyrin (MnTPPCl) was developed. The conversion of propylene was 12.7%, and the selectivity towards PO (propylene oxide) reached up to 80.5%. The formation of PO was attributed to the mechanism via high-valent Mn species, which was confirmed by means of in situ UV-vis spectrum.

Electrocatalytic hydrogenation (ECH) of biomass-derived feedstocks has a critical dependence on the molecular structure of the organic and its adsorption on the electrode surface. In this study, we investigated the role of functional groups in the adsorption of the organic molecule on the charged Pd (111) surface and its subsequent effect on organic reduction in electrochemical hydrogenation of organic molecules. With three aromatic carbonyls of benzaldehyde (BZD), acetophenone (ACE), and vanillin (VAN), we rationalize molecular-scale adsorption and interfacial charge transfer processes by employing density-functional-theory based ab initio molecular dynamics simulations. We observe that the functional group and electrode charge strongly affect the proximity of organic molecule to the Pd (111) surface, where distances of aromatic ring and carbonyl group of the organic on the electrode change distinctively with functional groups and charge state of electrode, which strongly impact reduction of organics on the surface. Calculations of differential electron density show the strongest reduction with benzaldehyde via interfacial electron transfer from the charged Pd surface. We also observe that the interaction between the functional groups and solvent (VAN > BZD > ACE) significantly influence the organic interaction with the charged electrode (BZD > VAN > ACE), resulting in the net interaction energy between the organic and the electrode in the order of BZD > ACE > VAN. Experimental measurement of ECH rate also show the same trend of the net interaction energy. These results demonstrate the significance of solvent effect on the reducibility of organic molecules on electrodes.

To explore the improving effect of Y2O3 on the water resistance of xY2O3-(100–x)(0.05Al2O3-0.15ZnO-0.15Na2O-0.65B2O3) (x = 0, 0.7 mol%, 1.4 mol%, 2.1 mol%, 2.8 mol%) glasses, glass structure and ion migration characteristics were respectively characterized by an infrared spectrometer and an electrochemical workstation. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to comprehensively analyze the alteration products. The experimental results show that with the increase of Y2O3 content, the mass loss per unit area of the glass is significantly reduced, and pH in leaching solution has the same change trend with mass loss of the glass, which indicates the improving effect of Y2O3 addition on the studied glass. The content of [BO4] structural unit and dc conductivity of glass increase firstly and then decrease with the increase of Y2O3 content, and reach a maximum at x = 0.7 mol%. Although addition of Y2O3 plays the role in the changes of glass structure and ion migration characteristics, the more important influence of Y2O3 is on the glass surface alteration layer. Y and Zn elements are enriched on the glass surface and finally transformed into an alteration layer, moreover, the adhesion between the alteration layers and the glass matrix is enhanced with the increase of Y2O3 content, which effectively blocks the further interdiffusion between the water molecules and the glass matrix.

Constructing molecule@support composites is an attractive strategy to realize heterogeneous molecular electrocatalysis. Herein, we synthesized metal-organic framework (MOF)-supported molecular catalysts for hydrogen evolution and oxygen reduction reaction (HER/ORR). Ligand exchange strategy was used to prepare molecule@support hybrids due to the same functional group. A series of hybrids were obtained using Co porphyrin (1) and different MOFs including MIL-88(Fe), MOF-5(NiCo) and UIO-66(Zr). The 1@MOF-5(NiCo) had the best HER and ORR activity compared with 1@MIL-88(Fe) and 1@MOF-5(NiCo). These hybrids also exhibited tunable selectivity for ORR with four-electron process, which can be attributed to the synergistic effect of porphyrin molecules and MOFs. This work provides a possibility for molecular catalysts to improve activity of HER and tune selectivity of ORR.

Vacuum gas oil (VGO) is the most important feedstock for hydrocracking processes in refineries, but its molecular composition cannot be fully acquired by current analysis techniques owing to its complexity. In order to build an accurate and reliable molecular-level kinetic model for reactor design and process optimization, the molecular composition of VGO has to be reconstructed based on limited measurements. In this study, a modified stochastic reconstruction-entropy maximization (SR-REM) algorithm was applied to reconstruct VGOs, with generation of a general molecule library once and for all via the SR method at the first step and adjustment of the molecular abundance of various VGOs via the REM method at the second step. The universality of the molecule library and the effectiveness of the modified SR-REM method were validated by fifteen VGOs (three from the literature) from different geographic regions of the world and with different properties. The simulated properties (density, elemental composition, paraffin-naphthene-aromatics distribution, boiling point distribution, detailed composition of naphthenes and aromatics in terms of ring number as well as composition of S-heterocycles) are in good agreement with the measured counterparts, showing average absolute relative errors of below 10% for each property.

Herein, we report on the guest-responsive hierarchical self-assembly of dissymmetric cage DC-1 with an intrinsic dipole along its C3-symmetric axis. DC-1 molecules self-assemble into supramolecular...

The engineering of switchable molecules with dramatic magnetic change is currently among the most active areas in chemical research. Here, two cyanide-bridged mixed-valence {FeIII4FeII4} cubes were...

Mechanically interlocked molecules (MIMs) and host–guest chemistry have received great attention in the past few decades. However, it remains challenging to design architectures with mechanically i...

We report the structural and electronic properties of narrow chevron-like graphene nanoribbons with a band gap of 1.5 eV. Molecular heterojunctions are formed during on-surface synthesis via a coupling defect consisting of a 5- and 6-membered ring.

Along this research the (110), (101) (200) and (211) surfaces were chosen to be studied by considering their atomic surface density. The surfaces were studied using CASTEP for the transition state search by DFT calculations, the initial coordinates that establish the SnO2-Methane distance were obtained with Adsorption Locator, a software able to calculate adsorption configurations using Monte Carlo methods. The results show that in terms of overall energy change, surface (101) presents the most favorable configuration with an exothermic total-energy change (form CH4 on the surface to a CO and H2O molecules on the surface) of − 18.47 kcal/mol, being the worst case the CH4 on a (200) surface with an endothermic total energy-change of 128.86 kcal/mol. In terms of the TS energy, the (101) surface remains as the most favorable system with energy maximums on the TS reaction path of 99.25 kcal/mol for the dissociation and adsorption of the CH4 molecule on the surface, and a maximum of 266.42 kcal/mol for the desorption and formation of the CH4 and H2O molecules on the SnO2 surface.

Understanding the impact of substituents on the quantum interference effect at single molecule scale is of great importance for the design of molecular devices. In this work, three platinum(II) complexes with -H, -NH2 and -NO2 groups on conductive backbones were designed and synthesized. Single-molecule conductance, which was measured using scanning tunnelling microscope break junction (STM-BJ) technique, demonstrated a conductance freeze phenomenon under the variation of substituents. Theoretical study revealed that, despite the electronic effect of the substituents shifting the energy level of molecular orbital, the quantum interference effect vanished the influence of electronic effect on the conductance and eventually leaded to the conductance freeze.

An efficient photo-Fenton catalyst (FeS2@HTCN) was designed by maximizing the synergistic effect of FeS2 nanoparticles and hollow tubular g-C3N4 (HTCN). Molecule self-assembly and molten salts-assisted calcination were used to engineering the hollow structured g-C3N4 before anchoring FeS2 nanoparticles on the walls of HTCN via reflux method. Compared to bulk g-C3N4, the unique structure of HTCN and heterojunction in the composite endowed FeS2@HTCN with more active sites and abundant channels for electron transfer and charge separation. The enriched electrons can improve the Fe3+ recycling and boost Fe2+ catalyzed •OH production via H2O2. As-prepared photo-Fenton catalyst was successfully applied to the treatment of industrial paint wastewater. The paint wastewater with its COD as high as 8200 mg/L can be effectively degraded with 0.2 mol/L H2O2 in 90 min under visible light irradiation. The photo-Fenton system was further evaluated according to the process stability and economic benefit, proving that the strategy presented in this work would be applicable to the treatment of real wastewater.

Two primitive metal-organic frameworks (MOFs), NiL1 and NiL2, based on Ni8O6-cluster and ditopic pyrazolate linkers, L1 (with rigid alkyne arms) and L2 (with flexible alkyne chains), were prepared. The proton conductivities of these MOFs in pristine form and imidazole-encapsulated forms, Im@NiL1 and Im@NiL2, were measured and compared. Upon introduction of imidazole molecules, the proton conductivity could be increased by 3 to 5 orders of magnitude and reached as high as 1.72 × 10−2 S/cm (at 98% RH and 80 °C). Also, whether imidazole molecules were introduced or not, Ni8O6-MOFs with L2 in general gave better proton conductivity than those with L1 signifying that flexible side arms indeed assist proton conduction probably via establishment of efficient proton-conducting channels along with formation of highly ordered domains of water/imidazole molecules within the network cavities. Beyond the active Ni8O6-cluster, tuning flexibility of linker pendants serves as an alternative approach to regulate/modulate the proton conductivity of MOFs.

Catalytic potential of carbon nanomaterials in peroxydisulfate (PDS) advanced oxidation systems for degradation of antibiotics remains poorly understood. This study revealed ordered mesoporous carbon (type CMK) acted as a superior catalyst for heterogeneous degradation of sulfadiazine (SDZ) in PDS system, with a first-order reaction kinetic constant (k) and total organic carbon (TOC) mineralization efficiency of 0.06 min‒1 and 59.67% ± 3.4% within 60 min, respectively. CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics, verifying the broad-degradation capacity of antibiotics. Under neutral pH conditions, the optimal catalytic parameters were an initial SDZ concentration of 44.0 mg/L, CMK dosage of 0.07 g/L, and PDS dosage of 5.44 mmol/L, respectively. X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites, contributing to the high catalytic activity. Free radical quenching analysis revealed that both SO4•− and •OH were generated and participated in catalytic reaction. In addition, direct electron transfer by CMK to activate PDS also occurred, further promoting catalytic performance. Configuration of SDZ molecule was optimized using density functional theory, and the possible reaction sites in SDZ molecule were calculated using Fukui function. Combining ultra-high-performance liquid chromatography (UPLC)–mass spectrometry (MS)/MS analysis, three potential degradation pathways were proposed, including the direct removal of SO2 molecules, the 14S-17N fracture, and the 19C-20N and 19C-27N cleavage of the SDZ molecule. The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.

A linear supramolecular polymer with controllable features based on twisted cucurbit[14]uril (tQ[14]) and cucurbit[8]uril (Q[8]) was firstly fabricated via an effective self-sorting strategy. Herein we designed a monomer, 1-butyl-1′-(naphthalen- 2-ylmethyl)-4,4′-bipyridinium bromide (BNB), that contains bipyridyl, aliphatic butyl and aromatic naphthyl groups, simultaneously. Two host molecules, tQ[14] and Q[8] were employed to develop an effective strategy for constructing a linear supramolecular polymer with controllable features. The alkyl groups on both sides of BNB could insert into the two cavities of tQ[14], the naphthyl part of BNB via π-π stacking in Q[8] cavity, serving as the driving force for supramolecular polymerization. Through self-sorting of the monomer, tQ[14] and Q[8], led to the formation of the linear supramolecular polymer. Depolymerization could be achieved by addition of adamantane hydrochloride (AH) which driven two BNB guest molecules out of the Q[8] cavity. This self-sorting strategy has great potential, not only for designing supramolecular polymer materials with different controllable structures through introduction of multiple functional groups, but also for broadening the application of twisted cucurbit[14]uril in supramolecular chemistry.

Cationic polymers, also known as polycations, are considered to be the most potential non-viral gene carriers due to their unique advantages such as the ability to bind the negative charge of nucleic acid molecules. Multicomponent polymerization (MCP) is a one-step, tandem strategy to construct complex structures based on multicomponent reactions. Herein, we developed a metal-free MCP method based on three monomers of p-dinitrovinylbenzene (p-DNVB), 1,1-dimethylethyl N,N-dibromocarbamate (BocNBr2), and bis-secondary-amines with a ratio of 1:2:1, to access a library of Boc-substituted polyamidines with well-defined structures and suitable molecular weights (Mw ranging from 4400 Da to 11000 Da) in high yields (up to 85%) under mild conditions. Upon the removal of Boc groups, a series of water-soluble polymers with cationic property were prepared and their gene binding capability was further evaluated.

Energy transfer as an important component in light-harvesting antenna systems can mimic effectively natural photosynthesis processes, showing great potential in optoelectronic devices. Herein, we report a responsive polymeric hydrogel based on the combination of excited state intramolecular proton transfer (ESIPT) molecule (Salicylic acid, Sal) and terbium (III) (Tb3+), as enabled by external stimuli to construct artificial light-harvesting antenna systems. Benefiting from unique photophysical properties of Sal, the synthesized hydrogel displays a temperature-dependent reversible opaque ↔ transparent states transition, accompanied with an interesting photoluminescence behavior. Moreover, by further incorporating europium (III) (Eu3+) into the hydrogel, we demonstrate well-defined cascades of energy transfer that provides a tunable optical output from the collection of lanthanides by the excitation of a common sensitizer (Sal) upon base vapor stimulation. Efficient energy transfer efficiency from Tb3+ to Eu3+, as high as 97.8%, was also obtained as established by the time-resolved fluorescence spectroscopy analysis.

Herein, we report an unprecedented regiospecific oxidative Mizoroki-Heck type reaction for the synthesis of ɑ-difluoromethyl homoallylic alcohols. The reaction shows broad substrate scopes and high functional group tolerance. Late-stage functionalization of complex biologically active molecules demonstrates the synthetic potential of this transformation. Mechanistic study supports the involvement of MnBr2 catalyzed radical 1,2-silyl transfer.

Upconversion nanosensitizers have been widely considered to have important applications in the treatment of major diseases such as tumors and the utilization of solar energy. Majority of the efforts so far have been focused on improving the efficiency of energy transfer (ET) between upconversion nanoparticles (UCNPs) and the anchored sensitizers with premise that high ET efficiency will lead to high acceptor efficacy. This premise is, however, proved by our current work to be invalid for commonly used load. Interaction between adjacent sensitizing molecules was found to be critical which undermines the amount of excited monomer sensitizers and thus fades the efficacy. Here NaYF4:Yb3+,Er3+ UCNPs and rose bengal (RB) photosensitizer molecules were used as the model energy donors and acceptors, respectively. Contrary to monotonous increase of the ET efficiency from UCNPs to RB species with increasing RB loading, acceptor efficacy characterized by the reactive oxygen species, as well as the RB fluorescence, exhibits bizarre dependence on the RB loading. The underlying mechanism was well studied by the steady-state and time-resolved spectroscopy of a series of samples. RB aggregates are believed to be responsible for the severe deviation between the ET efficiency and acceptor efficacy. The conclusion was validated by in vitro test where the photodynamic therapy with the most monomer RB in UCNPs-RB nanosensitizers kills 35.8% more cells than that with the highest RB loading. This understanding sheds light on construction of new ET based nanosystems for broad applications, such as medicine, solar energy utilization and optical storage.

Two bi-part combined models containing Reaction Equilibrium Thermodynamic Model and an equation of state (EoS) including cubic plus association (CPA) or modified Soave-Redlich-Kwong (SRK), were employed to correlate H2S solubility in ionic liquids [emim][Lac], [bmim][Ac] and [emim][Pro]. RETM and CPA/mSRK are responsible for chemical and phase equilibria calculations, respectively. The RETM defines a complex formation reaction between an H2S and two IL molecules into the liquid phase so that a complex in the form of H2S(IL)2 is probable to produce. On the other side, CPA/mSRK EoSs perform phase equilibria computations to find pressure and vapor phase concentrations. In the case of CPA, both of H2S and the ionic liquids were considered as self-associating components which pursue 4C and 2B schemes, respectively. This model computes the pure IL parameters using experimental density data. In this work, critical properties were estimated through the modified Lydersen-Joback-Reid method, Eotvos and Guggenheim relations. Afterward, the binary systems were investigated by applying RETM. CPA presents average absolute deviations (AADs) equal to 2.41%, 13.42% and 3.52% for [emim][Lac], [bmim][Ac], and [emim][Pro], respectively. Moreover, the AADs obtained by mSRK are 3.75%, 5.07%, and 6.06%, respectively. As it is evident from the results, the combination of RETM with both CPA and mSRK EoSs will result in good correlation accuracy.

Carbon nanotube-based (CNT-based) interfacial evaporation material is one of the most potential materials for solar desalination. Here, we studied the evaporation rate of the CNT-based membranes with different hydrophilic and hydrophobic chemical modified surfaces using molecular dynamic simulations. We found that the hydrogen bonding density among water molecules at the interface is a key factor in enhancing the evaporation rate. For a hydrophilic CNT-based membrane, the strong interactions between the membrane outer surface and the water molecules can destroy the water-water hydrogen bonding interactions at the interface, resulting in the reduction of the hydrogen bonding density, leading to an enhancement effect in evaporation rate. We also found that there is an optimal thickness for evaporation membrane. These findings could provide some theoretical guidance for designing and exploring advanced CNT-based systems with more beneficial performance in water desalination.

Nitrous oxide (N2O) is a greenhouse gas (GHG) mainly issued from agriculture and waste management activities. Since N2O has a global warming potential 298 times higher than CO2 and an annual emission equivalent to 5.1 % v/v of total GHG emissions, the control of its emissions becomes essential. One of the main challenges to control N2O emissions is to capture them under the main sources’ conditions, i.e. atmospheric pressure and ambient temperature. The available technologies to control N2O emissions operate presently at medium/high pressure, being high energy consuming. The development of new and specific adsorbents for capturing N2O is important. Molecular modeling is a helpful tool to develop engineered adsorbents, generating virtual molecular interactions as a prior adsorbate-adsorbent system before experimental studies. Zeolitic Imidazolate Framework-8 (ZIF-8) has been selected in this study as an adsorbent because of its easy and reproducible synthesis, thermal stability, flexible structure, hydrophobicity and high adsorption capacity of gases, including GHGs. In the present study, the interactions between N2O and ZIF-8 were studied by molecular modeling methods, PM6 and DFT. Optimized geometries of N2O and ZIF-8, adsorption energy and ligand point length parameters were analyzed as part of a physical adsorption process. Three adsorption sites were identified on the four-membered and six-membered windows of ZIF-8. The two possible N2O interaction configurations (–ONN and –NNO) were simulated and compared in order to determine the most probable behavior of N2O. The study showed that the –ONN configuration produces more stable interactions with ZIF-8 than –NNO configuration. The six-membered window of ZIF-8 seems to be the pore where the most stable interactions occur based on the adsorption energy and the approach distance. The present study was concentrated on the interactions of one N2O molecule and a fragment of the ZIF-8, and it will be the basis for molecular dynamics simulations of adsorption with a control volume, containing several N2O molecules and a representative surface of ZIF-8 under different pressures and temperatures.

Hydrogen-bonded molecules and their dynamics are significantly important in chemistry and biology due to their widespread functionality. Besides their natural abundance and diversity, applications ...

The transformations of CO2 molecules into valuable products are of increasing interest due to the negative impact of anthropogenic CO2 emissions on global warming. The CO2-to-methanol hydrogenation is an economically profitable reaction of carbon fixation, but it still steps away from widespread industrialization because of the lack of efficient and selective catalysts. Recently, single-atom alloy (SAA) catalysts have been developed to work remarkably in CO2 hydrogenation reactions. Doping isolated single atoms into metallic catalyst can dramatically alter the catalytic performance of the host. We have performed a screening discovery on Ru and 6 RuX (X = Fe, Co, Ni, Cu, Ir and Pt) SAAs using density functional theory (DFT) computations. We considered 13 possible elementary reactions in 4 possible reaction pathways on Ru and all RuX surfaces. In the computed mechanisms, we found that the formation of *H2COOH and *HCOO intermediates plays a critical role in determining catalysts’ activities. Doping Co and Pt isolated single atoms into Ru surface can thermodynamically and kinetically facilitate these intermediates formation processes, eventually promoting the production of methanol. The combination of weak binding and enhanced charge redistribution on RuCo and RuPt surfaces give them improved catalytic activities over pure Ru. This work will ultimately facilitate the discovery and development of SAAs for CO2 to methanol, serving as guidance to experiments and theoreticians alike.

The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cyclopropyl alkyne catalyzed by in situ generated Cu(I) from the comproportionation reaction of Cu(II) salt and Cu powder under mild reaction conditions. The reaction proceeds via sequential acetylenic coupling, followed by cyclization and [2 + 2] cycloaddition to directly produce pentalene dimer, which is difficult to access by other established methods. Different mechanistic paths were studied for the pentalene formation using density functional theory, suggesting that the reaction also proceeds through acetylenic coupling followed by cyclization and [2 + 2] cycloaddition. Based on the activation energy barriers, Path 1 has the rate-determining step of 38.63 kcal/mol, which is the most thermodynamically preferred one among the four paths.

Erythromycin thiocyanate is widely used for the production of other macrolide antibiotics. In this work, a novel heterosolvate of this pharmaceutical compound has been obtained and characterized for the first time, which was transformed from the dihydrate form in the acetone solvent through evaporation crystallization. Thermal behavior together with compositional analysis revealed that both water and acetone molecules participated in the formation of the crystal lattice which is rarely reported before. The general chemical name of the heterosolvate may be defined as erythromycin thiocyanate sesquihydrate hemiacetonate. Furthermore, studies on solid-state spectral analysis provided strong evidence of intermolecular hydrogen bonds in heterosolvate crystals. According to the crystal structure determined by single crystal X-ray diffraction, the formation mechanism of the heterosolvate is proposed in which strong multi-hydrogen bondings between water and solute molecules form the layer structure. While acetone molecules form single-hydrogen bonds with solutes and reside in channels between layers. This well explains why acetone solvent is easy to escape from the crystal structure during desolvation.

Artificial membrane transporters that either use chalcogen bonds to facilitate transmembrane flux of anions or show high selectivity toward perchlorate anions are rare. In this work, we report on one such novel monopeptide-based transporter system, featuring both chalcogen bonds for highly efficient anion transport and high transport selectivity toward ClO4− anions. Structurally, these monopeptide molecules associate with each other via H-bonds to produce H-bonded 1D stack that not only one dimensionally but also directionally aligns the terminal bicyclic thiophene motifs to the same side. Functionally, these well-aligned thiophenes create a sulfur-rich transmembrane pathway, combinatorially fine-tunable to enable anions to efficiently cross the membrane in the increasing activity of Cl−

The crystalline sponge method is a pragmatic and promising strategy for molecular structure determination. However, the dominant metal–organic framework crystal sponge platforms always face poor ch...

The process of selectively introducing a CF3 group into an organic molecule using inexpensive, stable, and solid sodium trifluoromethanesulfinate has rapidly advanced in recent years to become an eco-friendly method used by organic chemists to synthesize various natural and bioactive molecules. This review focuses on advances made within the last five years regarding C–H functionalisation, namely thermochemical C(sp2)–H (thio)trifluoromethylations, photochemical C(sp2)–H trifluoromethylations, and electrochemical C(sp2)–H trifluoromethylations, using Langlois’ reagent (NaSO2CF3).

Herein, we report a simple and efficient method for the direct installation of chlorodifluoroethyl group onto aromatic molecules of various aromatic amides with a new 2-chloro,2,2-difluoroethyl(mesityl)iodonium salt (CDFI). Moreover, the chlorodifluoroethyl compounds could be smoothly converted into difluorovinyl compounds in a one-pot or discrete procedure and regarded as a steady source of difluorovinyl compounds with “HCl-mask”.

Water-soluble pillar[5]arenes are a class of typical macrocycles and have aroused tremendous attention for its easy to modify, abundant host-guest properties and extensive applications. However, up to now, all the reported water-soluble pillar[5]arenes acted as the host molecules, whereas they failed to be postsynthetically modified, which seriously impeded the development of the pillar[5]arene-based supramolecular chemistry. In this work, a new water-soluble pillar[5]arene, pillar[4]arene[1]quinone, was designed and synthsized with eight quaternary ammonium groups as well as a quinone units. Such a new water-soluble pillar[4]arene[1]quinone was capable of forming 1:1 stable complex with sodium 1-octanesulfonate in aqueous solution. Since the 1,4-quinone unit of WP[4]Q[1] could react with ethylenediamine (EDA) to form a conjugated quinoxaline structure, so pillar[4]arene[1]quinone could apply to the facile fluorescence turn-on sensing of EDA in aqueous solution, organic solvent and air.

Several probes containing benzothiazole-guided conjugated systems (BGCS) were designed and synthesized, and two molecules (BGCS5 and BGCS6) of which were discovered as selective probes targeting c-MYC Pu22 G-quadruplex DNA. The fluorescence intensity of BGCS5 and BGCS6 in the presence of c-MYC Pu22 far exceeds that of the typical G4 probe TO1. Especially, the fluorescence of BGCS6 increased almost 193-fold in the presence of c-MYC Pu22 G4 compared to that alone in aqueous buffer condition with almost no fluorescence and 10–30 folds than those in the presence of other DNAs, which will be useful tools for disease detection in mammals.

Molecules with multifunctional properties are of immense interest in hybrid materials, while challenges still existed because of the limited compatibility of multiple functionalities in a single system. In this work, a series of metal-organic complexes were synthesized and characterized under the assembly of electron donor phosphonate, electron acceptor polypyridine ligand and spin carrier rare earth ions. All the compounds exhibited remarkable and reversible responses with photochromism and photomodulated fluorescence, originated from photogenerated radicals via electron transfer from phosphonates to polypyridine ligands. For the Dy analog, slow magnetic relaxation was observed at cryogenic temperature, indicating the single-molecule magnetic behavior. Furthermore, photogenerated radicals could enhance the proton conductive behavior, with about 2 times larger in magnitude after light irradiation for Dy and Y compounds. The introduction of photoluminescence, magnetism and proton conduction into metallic phosphonates can provide potential applications for photochromic materials.

An approach for the construction of crystalline porous supramolecular organic frameworks (SOFs) via outer-surface interactions of cucurbit[6]uril (Q[6]) with high yield is presented. This approach enables the noncovalent integration of guest molecules into ordered topologies and creates new host–guest-complex-based SOFs; i.e., the topology can be predesigned and constructed by using [ZnCl4]2− anions to induce the formation of solid Q[6]-SOFs, and the pore wall surface can be easily modified by the Q[6]-encapsulated guest molecules. In addition, one of prepared solid Q[6]-SOFs showed a high drug-loading capacity and smart potential release control for drug-delivery applications

An enantioselective [4+1] spiroannulation of α-bromo-β-naphthols with azoalkenes has been developed for the one-step construction of a new class of pyrazoline-based spirocyclic molecules. Using chi...

Summary Ammonia synthesis is structure sensitive, and a minute change in the catalyst structure would cause a dramatic change in activity. To date, none of the studies reveal the metal size effect at a subnanometer scale on NH3 synthesis, and such investigation remains a challenge. Here, we report the synthesis of Ru catalysts with sizes ranging from single atoms, atomic clusters (ACCs), sub-nanometric clusters, to nanoparticles (NPs) by adjusting precursor and/or loading of Ru. Sub-nanometric Ru catalysts not only exhibit performance different from that of NPs but also follow a different route for N2 activation. The strong intra-cluster interaction of Ru atomic clusters enables the formation of strong interactions of Ru d-orbitals with the σ and π orbitals of N2 molecules, resulting in N2 activation over Ru ACCs to occur more easily than that over Ru NPs. Consequently, Ru ACCs display an unprecedentedly high NH3 synthesis rate and large turnover frequency at mild conditions.

Molecular self-assembly is the most important strategy for the development of chiral aggregates and chiral functional materials. In this study, we rationally designed and synthesized chiral fluorescent heteroclusters that were self-assembled into microscale cubosomes with a three-dimensional (3D) bicontinuous cubic phase nanostructure. The cubosomes exhibited chirality, indicating that chirality is transferred from the molecules to the 3D nanostructure. Therefore, we confirmed the formation of a chiral bicontinuous cubic phase nanostructure for the first time. We also showed that this chirality originates from the continuous change in the saddle-splay distortion of the molecules within the curved bilayer. At the same time, transparent films of chiral composites were prepared by mixing the chiral cubosomes with an epoxy resin and then curing the mixture. Therefore, we demonstrated an effective method for preparing chiral composites.

Ketones are one of the most important classes of organic compounds, and widely present in various pharmacological compounds, biologically active molecules and functional materials. Over the past few decades, transition metal-catalyzed conversion of aldehydes has been found to be a powerful method. With the continuous development in recent years, it has become an efficient and uncomplicated strategy for constructing ketones. There are four major mechanisms for transition metal-catalyzed ketone synthesis from aldehyde: (1) carbonyl-Heck reaction, that is 1,2-insertion of organometal species to aldehydic C=O double bond, (2) direct insertion of transition metal catalysts to aldehydic C-H bond, (3) aldehyde as acyl radical, (4) aldehyde as carbon radical acceptor. This article summarizes related reports on the transformations of aldehydes to generate corresponding ketones under different reaction conditions.

Herein, we report a computational algorithm that follows a spectroscopist-driven elucidation process of the structure of an organic molecule based on IR, $^1$H and $^{13}$C NMR, and MS tabular data. The algorithm is independent from database searching and is based on a bottom-up approach, building the molecular structure from small structural fragments visible in spectra. It employs an analytical combinatorial approach with a graph search technique to determine the connectivity of structural fragments that is based on the analysis of the NMR spectra, to connect the identified structural fragments into a molecular structure. After the process is completed, the interface lists the compound candidates, which are visualized by the WolframAlpha computational knowledge engine within the interface. The candidates are ranked according to the predefined rules for analyzing the spectral data. The developed elucidator has a user-friendly web interface and is publicly available (http://schmarnica. si).

RNA molecules with repeat expansion sequences can phase separate into gel-like condensate, and this process may lead to neurodegenerative diseases. Here we report that in the presence of Mg2+ion, RNA molecules containing 20×CAG repeats coacervate into filled droplets or hollowed condensate. Using hyperspectral stimulated Raman spectroscopy, we show that RNA coacervation is accompanied by the stacking and clustering of nucleobases, while forfeiting the canonical base-paired structure. At an increasing RNA/Mg2+ratio, the RNA droplets first expand in sizes, and then shrink and adopt hollow vesicle-like structures. Significantly, for both large and vesicle-like droplets, the nucleobase-clustered structure is more prominent at the rim than at the center, accounting for the rigidification of RNA droplets. Thus, our finding has broad implications for the general aging processes of RNA-containing membrane-less organelles.

Actively controlling the performance of surface-enhanced Raman scattering (SERS) holds great promise in enabling novel applications of this technique. As a popular two-dimensional material, graphene shows intriguing tunable properties and thus has become a promising material in many potential active device applications. Here we proposed and experimentally demonstrated low-voltage electrically tunable SERS by using a plasmonic gold nanorod-graphene/ion-gel hybrid structure. The SERS signals of molecules adsorbed on such a structure were found to be continuously tunable through an external small bias voltage. As such a tuning process is highly related with the charge transfer between the adsorbed molecules and graphene, the proposed design is also helpful in understanding the charge transfer-based enhancement mechanism of SERS.

Protein immobilization is an essential method for both basic and applied research for protein, and covalent, site-specific attachment is the most desirable strategy. Classic methods typically rely ...

Electrocatalysis plays an increasingly important role in converting atmospheric molecules (e.g., N2, CO2 and H2O) to value-added products (e.g., NH3, C2H4 and H2). However, developing a simple strategy for preparing catalysts with high performance for the effective conversion of clean energy is still full of challenges. Herein, we describe a straightforward, one-step reduction method to achieve the formation of Pt nanoparticles (NPs) and the vacancy engineering of TiO2–x nanofibers (NFs) simultaneously, which can be accomplished in 5 min. Furthermore, a Pt/TiO2–x nanofibrous aerogel (NA) with an ordered cellular architecture is prepared through a directional freezing technology. The Pt/TiO2–x NA with excellent mechanical properties can be made into a self-supporting electrode for electrocatalytic N2 reduction reaction (NRR), showing high NH3 yield rate (4.81 × 10–10 mol s–1 cm–2) and Faraday efficiency (14.9%) at –0.35 V vs. RHE.

The self-assembly characteristics of tetrathiafulvalene (TTF) derivatives molecules 1–3 at the 1-phenyloctane/HOPG (HOPG = highly oriented pyrolytic graphite) interface had been carefully studied by scanning tunneling microscopy (STM) method. The number of F atoms on the phenyl group had significantly affected the self-assembly structures. High-resolution STM images make clear the different assembly structures between the molecules 1–3, which attribute to the different F atom numbers and pyridine group in the molecule. Density functional theory (DFT) calculations have been performed to reveal the formation mechanism.

Electronic coupling between individual building blocks plays an essential role in charge transport through molecular materials and devices. However, the investigation of the transmission mechanism ...

Direct photocatalyzed hydrogen atom transfer (d-HAT) can be considered a method of choice for the elaboration of aliphatic C–H bonds. In this manifold, a photocatalyst (PCHAT) exploits the energy of a photon to trigger the homolytic cleavage of such bonds in organic compounds. Selective C–H bond elaboration may be achieved by a judicious choice of the hydrogen abstractor (key parameters are the electronic character and the molecular structure), as well as reaction additives. Different are the classes of PCsHAT available, including aromatic ketones, xanthene dyes (Eosin Y), polyoxometalates, uranyl salts, a metal-oxo porphyrin and a tris(amino)cyclopropenium radical dication. The processes (mainly C–C bond formation) are in most cases carried out under mild conditions with the help of visible light. The aim of this review is to offer a comprehensive survey of the synthetic applications of photocatalyzed d-HAT.