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The chiral separation of terbutaline (TB) using β-cyclodextrins (β-CD) and its derivatives has aroused intensive interest. Herein, the enantioseparation mechanisms of β-CD and heptakis(2,3-di-O-acetyl)-β-CD (HAD-β-CD) towards TB are investigated by a molecular dynamics/quantum mechanics/continuum solvent model (MD/QM/CSM) approach based on the experimental data. One of the two experimentally predicted binding modes of HAD-β-CD/TB is confirmed by our approach and ascribed to the R-complex. R-TB is compactly included by HAD-β- CD: the aromatic ring is within the CD cavity, while the alkyl moiety is also included and almost parallel to the secondary rim of the CD. As indicated by the computed binding affinity, this tight binding mode of R-complex enhances the host–guest hydrophobic interaction and renders the R-complex significantly more stable than the S-complex. In contrast, the binding modes of R- and S-TB with β-CD are similar due to the poor flexibility of the host, which jeopardizes its ability to differentiate R- and S-TB.

Solid-state polymer electrolytes (SPEs) with superior self-healing capacity are urgently required for next-generation flexible energy storage devices. Herein, a highly stretchable (extensibility > 4000% and stress > 130 kPa), non-flammable and notch-insensitive intrinsic self-healing solid-state polymer electrolyte (SHSPE) was prepared based on the combination of a poly(HFBM-co-SBMA) network, imidazole-based ionic liquid (EMI–TFSI) and LiTFSI. The incorporation of the imidazole cation and fluorine atom contributed to the formation of supramolecular bonds (ion–dipole interactions) inside the electrolyte framework, thus endowing SHSPE with prominent self-healing ability (recovery time 200 g). The as-assembled Li/SHSPE3/LiFePO4 battery delivered a high discharge capacity of 144.8 mA h g−1 at 0.2C, and its capacity retention ratio reached 82% after 100 cycles with a coulombic efficiency of 97%. In particular, the mechanical properties and conductivity of SHSPE3 could fully recover after repeated damage, conferring the derived soft-pack battery excellent anti-fatigue capability. The use of intrinsic self-healing principles in the field of SPEs provides new insight for developing reliable and safe flexible electronic devices.

Energetic self-healing adhesives have a positive effect on the energy level, mechanical properties, and microcrack healing performance of energetic composite materials (ECMs). However, it is very challenging to design and synthesize energetic self-healing adhesives with high healing efficiencies and satisfactory mechanical properties. Herein, this study introduced a new design strategy. Plentiful dynamic hydrogen bonds endow the adhesive with high-efficiency self-healing performance, and inspired by Parthenocissus, strong adhesion gives ECMs good mechanical properties. The basic characteristics of this design included: (1) loose hard domains; (2) rapid rearrangement of the hydrogen bonds; and (3) strong interfacial adhesion. The synthetic energetic adhesive polyglycidyl azide (GAP)–isophorone diisocyanate (IDI)–4,4′-methylenedianiline (MDA) completely recovered all mechanical properties within 2 h after breaking at room temperature. Simultaneously, the enthalpy of formation of 1.95 kJ g−1 indicated that the adhesive possesses a good energy level. Significantly, ECMs containing explosive crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and our designed energetic self-healing adhesive exhibited good mechanical properties and surprising crack-healing capabilities. In addition, compared with non-energetic adhesive-based ECMs, energetic adhesive-based ECMs exhibited excellent combustion properties. Therefore, the GAP–IDI–MDA adhesive demonstrated strong application potential and this strategy is expected to provide new ideas for the improvement of weapon system security.

A core–shell structure Cu–Ce–La/SSZ-13@ZSM-5 catalyst with a Cu–Ce–La/SSZ-13 core and a ZSM-5 shell was first synthesized by a self-assembly method and used for ammonia-selective catalytic reduction (NH3-SCR). In comparison with Cu–Ce–La/SSZ-13, Cu–Ce–La/SSZ-13@ZSM-5 with appropriate shell thickness presents better SCR activity and hydrothermal stability. We discovered an ion migration effect during the shell phase assembly process and further proposed that the ion migration effect was induced by the dissolution of the core phase during the growth of the shell. Part of the metal ions were migrated and redistributed during the assembly of the ZSM-5 shell, resulting in the transformation of [Cu(OH)]+–Z to Cu2+–2Z species and the functionalization of the shell phase. The functionalized shell is beneficial for the adsorption and activation of NH3. The results of an H2O resistance test and thermogravimetric analysis confirm that the coating of the hydrophobic shell can effectively improve the hydrothermal stability and H2O resistance of core–shell Cu–Ce–La/SSZ-13@ZSM-5.

Non-fullerene acceptors, especially acceptor-donor-acceptor structured fused-ring electron acceptors (FREAs), have attracted widespread attention in organic solar cells because of their versatile molecular design in fine-tuning light absorption and energy levels. We report the accuracy of Time-Dependent Density Functional Theory (TD-DFT) for FREAs by comparing their theoretically predicted vertical absorption wavelength (λver-abso) with the experimental maximum absorption (λmax). The λver-abso values of 50 molecules obtained from major types of FREAs have been investigated using TD-DFT by considering the solvent effects. The values of λver-abso predicted with a pure density functional (PBE), global hybrids (B3LYP and PBE0) and range-separated schemes (CAM-B3LYP and LC-ωPBE) follow the exact exchange percentage included at an intermediate inter-electronic distance. Global hybrids outperform all other schemes. The mean absolute error provided is 22 nm by PBE0 and 38 nm by B3LYP for the whole set of molecules. The maximum deviation of 92 nm provided by B3LYP and 69 nm provided by PBE0 confirms that PBE0 is more appropriate for predicting the absorption wavelengths when designing new FREAs. By applying linear regression analysis to obtain the calibration curve, we found that the range-separated methods provide an equal or even more consistent description of FREA excited states. For the whole set of molecules, linearly corrected data yield an average error of 25 and 27 nm for CAM-B3LYP and LC-ωPBE, respectively. Consequently, when a statistical analysis technique is applicable for a certain series of FREAs, a theoretical method permits a chemically comprehensive and empirically good explanation of UV/Vis spectra for newly-designed FREAs.

Acceptor–donor–acceptor structured fused-ring electron acceptors (FREAs) are the most efficient electron acceptors used in organic solar cells. We use density functional theory (DFT), its time-dependent version (TD-DFT), and an intra-molecular charge transfer index to evaluate the nature of the excited states of FREAs. Typically, several efficient electronic transitions contribute to the absorption spectra of FREAs. An investigation of every efficient electronic transition of each FREA is performed based on the electronic density variation in the donor and acceptor moieties of the molecules upon absorbing solar photons. Not all these transitions are equivalent for light-to-electricity conversion. The first transition contributes the most to the absorption spectra. This transition is intense and extremely efficient for light-to-electricity conversion, giving a higher value of intra-molecular charge transfer. For certain effective transitions of FREAs, the phenyl rings in the donor unit behave as the electron-donating units, such as IDT-NTI-2EH, BTCN-M, and MeIC. The foremost finding of the present research work is that the furthermost strong electronic transitions are not essentially the most effective ones for the conversion of sunlight into electricity.

The reaction mechanisms of Rh-catalyzed regioselective hydrothiolation of the allyl amine employing four bidentate phosphine ligands are investigated with DFT calculations. The free energy profiles of anti-Markovnikov and Markovnikov pathways arising from different alkene insertion types are computed to elucidate the ligand-controlled regioselectivity. For 1,2-bis(diphenylphosphino)benzene (dppbz) and 1,3-bis(diphenylphosphino)propane (dppp) ligands with small nature bite angle (βn ≤ 86°), the anti-Markovnikov pathway that features the 1,2-alkene insertion into Rh-H bond is favored by 2 ˜ 4 kcal/mol in barriers of elementary steps. While for 1,4-bis(diphenylphosphino)butane (dppb) and bis(2-diphenylphosphinophenyl)ether (DPEphos) ligands with large nature bite angle (βn ≥ 99°), the Markovnikov pathway with 1,2-alkene insertion into Rh-S bond is preferential by 2 ˜ 7 kcal/mol in barriers. The P-Rh-P bite angle is a reliable predictor and regulator of the regioselectivity of reaction as evidenced by good correlations between reaction barrier and P-Rh-P bite angle. Smaller P-Rh-P bite angle in TSs is generally found for small nature bite angle ligand dppbz and dppp in preferential anti-Markovnikov pathway, while TSs with larger P-Rh-P bite angle are favored by large nature bite angle ligand DPEphos and dppb. Larger difference in P-Rh-P bite angles of TSs between Markovnikov and anti-Markovnikov pathway generally leads to the greater disparity in barrier heights of two pathways, and hence greater regiodivergency of reaction.

A concerted one-step addition mechanism for anti-Markovnikov hydrothiolation in [Hmim]Br catalyzed thiol–ene reactions is revealed by a combined DFT and experimental study for the first time. This special mechanism represents a typical “ionic liquid effect”, which is driven by the directional hydrogen bond and π+–π interactions that conjoin the substrates and [Hmim]Br into a prereactive complex. The transition state is stabilized and characterized by a planar 6-membered ring containing HBr and four substrate atoms at the reaction site. The concerted addition mechanism and the special structural feature of the TS render the reaction regiospecific, i.e. only the anti-Markovnikov product is produced. When the styrene is replaced by aliphatic alkenes, the substrates are loosely bound with the ionic liquid. As a result, the prereactive complex is destabilized and the reactivity drops significantly.

The catalytic potential of pyridine-2-carboxlic acid has been evaluated for efficient, green and solvent free synthesis of 2,4,5-trisubstituted imidazole derivatives 3a-3m. The compounds 3a-3m were synthesized by one pot condensation reaction of substituted aromatic aldehydes, benzil, and ammonium acetate in good to excellent yields (74-96 %). To explore the potential of these compounds against Alzheimer's disease, their inhibitory activities against acetylcholinesterase (AChE) were evaluated. In this series of compounds, compound 3m, bearing one ethoxy and a hydroxy group on the phenyl ring on 2,4,5-trisubstituted imidazoles, proved to be a potent AChE inhibitor (102.56±0.14). Structure-activity relationship (SAR) of these compounds was developed. Molecular dockings were carried out for the compounds 3m, 3e, 3k, 3c, 3a, 3d, 3j, and 3f in order to further investigate the binding mechanism. The inhibitor molecule was molecularly docked with acetylcholinesterase to further study its binding mechanism. The amino group of the compound 3m forms an H-bond with the oxygen atom of the residue (i. e., THR121) which has a bond length of 3.051 Å.

The reaction of dimorpholinomethane in fuming HNO3 was investigated. Interestingly, the major product was identified as N-nitrosomorpholine and a key intermediate N-hydroxymethylmorpholine was detected during the reaction by 1H-NMR tracking which indicates that the reaction proceeds via an unexpected nitrosolysis process. A plausible nitrosolysis mechanism for N-hydroxymethyldialkylamine in fuming nitric acid involving a HNO3 redox reaction is proposed, which is supported by both experimental results and density functional theory (DFT) calculations. The effects of ammonium nitrate and water on the nitrosolysis were studied using different ammonium salts as additives and varying water content, respectively. Observations show the key role of ammonium ions and a small amount of water in promoting the nitrosolysis reaction. Furthermore, DFT calculations reveal an essential point that ammonia, merged from the decomposition of the ammonium salts, acts as a Lewis base catalyst, and the hydroxymethyl group of the substrate participates in a hydrogen-bonding interaction with the NH3 and H2O molecules.

Naphthalenes, a class of persistent organic pollutants, are difficult to remove from environment due to their low water solubility. β-cyclodextrin (β-CD) and its derivatives can encapsulate these compounds and enhance their solubility. For OH-substituted naphthalenes, several inclusion complexes with β-CD and 2,6-di-methyl-β-CD (DMCD) of varying stabilities were reported. However, the role of non-covalent interaction was not defined and the binding mechanisms remain vague. We use a molecular dynamics/quantum mechanics/continuum solvent model to explore the inclusion mechanisms of these systems. Both the measured binding modes and binding trend are well reproduced by our computations. The host-guest non-covalent interaction favors the β-CD complexes, while the hydrophobic interaction favors the DMCD complexes, and the latter plays a more important role in determining the binding trend. A correlation between the polarizability of the inclusion complex as measured by its dipole moment and hydrophobic interaction is also revealed.

A new furfuran-based rhodamine B fluorescent probe (RBFF) has been designed and synthesized, and its sensing behavior towards various metal ions was evaluated via UV–vis and fluorescence spectroscopic techniques. RBFF exhibits a highly sensitive and selective “turn-on” fluorescent response toward Fe3+ ion and a fluorescence “turn-off” response when added B4O72− to the RBFF-Fe3+ in the EtOH/H2O solution (1:1, v/v, HEPES, 1 mM, pH 7.20). The detection limit of RBFF for Fe3+ was calculated to be 0.025 μM. The fluorescence microscopy experiment suggested that RBFF could also be served as a biological fluorescence probe for the detection of Fe3+ in human cervical carcinoma cells (HeLa).

A new fluorescent probe ( TRDM-F ) based on a molecular chain of open-loop maleic anhydride, rhodamine B and fluorescein was designed, synthesized and evaluated to develop a chemosensor. Photochemical studies show that fluorescence properties of TRDM-F are dominated by fluorescein group in the pH range of 2–10. UV–vis absorption and fluorescence spectroscopic studies further display a high selectivity towards Cys over GSH/Hcy and other amino acids and a high sensitivity towards Cys (0.088–270 μM) with 95-fold fluorescence enhancement in a HEPES buffer solution (10 mM, pH = 7.4) containing 20% MeCN at room temperature. We further demonstrated that the proposed method was satisfactorily applied to the discrimination of Cys in living Hela cells with low cell toxicity.

A carbazole-based hole-transporting material named 4,4′,4′′,4′′′-(9-octylcarbazole-1,3,6,8-tetrayl) tetrakis(N,N-bis(4-methoxyphenyl)aniline) (CZ-TA) has been developed through a one-step facile synthesis approach. The solution-processed planar perovskite solar cells (PVSCs) with 50 nm thick CZ-TA hole selective layer (HSL) contributes a power conversion efficiency of 18.32%, comparable to the most commonly used 200 nm spiro-OMeTAD (18.28%) HSLs. The improved hole extraction, transport and reduced recombination are found to endow CZ-TA-based devices with impressive fill factors over 81.0%. Importantly, the unit cost of HSL in PVSCs using CZ-TA can be as low as only 1/80 of that of spiro-OMeTAD, indicating that CZ-TA could be a promising candidate as HSLs for commercialization of the low-cost PVSC technology.

The interactions between bile salts and modified cyclodextrins (CD) have aroused intensive interest because of their influence on the in vivo drug release within the small intestine. We use a recently proposed molecular dynamics/quantum mechanics/continuum solvent model (Ye et al. in Chem Phys Lett 648:170, 2016) to investigate the microscopic binding mechanisms of the natural, dimethylated (M200), randomly methylated (M214), and trimethylated (M300) $$\beta$$ -CDs, with glycocholate (GC). The computed binding free energies of the four CDs with GC decrease in the following order: natural $$\beta$$ -CD > M200 > M214 > M300, which is in accord with the experimental data. As suggested by the computed thermodynamic quantities, the relative stabilities of the four CD/GC complexes are determined by both the host–guest interactions (enthalpy plus entropy) and the solvent effects. Moreover, the former favors M200, while the latter favors natural $$\beta$$ -CD. For M300, both factors are in disadvantage.

A new rhodamine B derivative, namely, N1-(benzo[d]thiazol-2-yl)-N4-(2-(3′,6′-bis (diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)ethyl)malea-mide (RDBSF), was designed, synthesized, and structurally characterized to develop a new chemosensor. UV–vis absorption and fluorescence spectroscopic studies show that RDBSF exhibits high sensitivity and selectivity toward Fe3+ in the presence of many other metal cations in a Tris-HCl solution (1 mM, pH = 7.4) containing 30% MeCN by forming a 1:1 complex with Fe3+. The binding association constant (Ka) of RDBSF for Fe3+ was estimated as 1.52 × 104 M−1 in the solution. The detection limit of Fe3+ by RDBSF was further determined as 11.6 nM. Intracellular imaging applications demonstrated that RDBSF can be used as a fluorescent probe for the detection of Fe3+ in HepG-2 cells.

The length and conformation of solubilizing side chains in π-conjugated polymers impact polymers' self-assembling properties in thin-film devices. To reveal the effect of different bisalkylthio side chains, four copolymers containing bisalkylthio side chain modifying two-dimensional benzo[1,2- b :4,5 -b ′]dithiophene (BDT) donor with (5,6-difluoro-4,7-di(thiophen-2-yl)benzo[ c ][1,2,5]thiadiazole (BDff) acceptor have been developed and studied in this report. The different absorption maxima ( λ max ) of PBDTT-DS1-BTff , PBDTT-DS2-BTff , PBDTT-DS3-BTff and PBDTT-DS4-BTff are 578, 574, 591 and 594 nm in CHCl 3 solution, respectively, indicating different aggregation behaviors. The devices based on PBDTT-DS1-BTff didn't reveal high PCEs due to its poor miscibility with PC 71 BM compared to those with other polymers. The devices blending PBDTT-DS2-BTff with PC 71 BM exhibited a highest PCE of 5.82%, with an enhanced J SC of 11.06 mA cm −2 , a V OC of 0.92 V and a FF of 57.2%. This work demonstrates that suitable side chain lengths in π-conjugated polymers are of great significance in optimizing the performance of polymers based solar cells.

In this study, three copolymers containing bisalkylthio side chain modifying two-dimensional benzo[1,2-b:4,5-b′]dithiophene (BDT) donor with different electron-deficient acceptors were synthesized. The copolymers were characterized using a combination of thermal analysis, UV–visible spectroscopy, cyclic voltammetry, and theoretical calculations. All copolymers exhibit deep HOMO energy levels from −5.52 eV to −5.60 eV, correspondingly resulting in high VOC. The photovoltaic properties of the copolymers were also studied systematically. The best devices blending PBDT-DTBTff with PC71BM exhibited a best PCE of 7.65%, with a VOC of 0.86 V, a JSC of 13.32 mA cm−2 and a FF of 66.8% due to its high hole mobility (1.1 × 10−3 cm2 V−1 s−1) and facilitated exciton dissociation and charge transport. This work demonstrates an effective method to tune HOMO energy levels of BDT-based copolymers through introducing bisalkylthio side chain into BDT donor. And this result also demonstrates the significance of the interaction and match between donor-acceptor units providing related polymer with suitable band gap and HOMO/LUMO energy levels.

Hf-MOF-808 exhibits excellent activity and specific selectivity on the hydrogenation of carbonyl compounds via a hydrogen transfer strategy. Its superior activity than other Hf-MOFs is attributed to its poor crystallinity, defects and large specific surface area, thereby containing more Lewis acid-base sites which promote this reaction. Density functional theory (DFT) computations are performed to explore the catalytic mechanism. The results indicate that alcohol and ketone fill the defects of Hf-MOF to form a six-membered ring transition state (TS) complex, in which Hf as the center of Lewis stearic acid coordinates with the oxygen of the substrate molecule, thus effectively promoting hydrogen transfer process. Other reactive groups, such as –NO2, C = C, -CN, of inadequate hardness or large steric hindrance are difficult to coordinate with Hf, thus weakening their catalytic effect, which explains the specific selectivity Hf-MOF-808 for reducing the carbonyl group.

Pillared-layer framework MOFs are considered to be energetic for enhanced performance for anode materials because of rich space and channels for lithium insertion and extraction. We selected pillared-layer MOF, Co(BDC)TED0.5, consisting of an aromatic organic ligand (Terephthalic acid: 1,4-H2BDC) and pillar ligand (Triethylenediamine: TED), synthesized via facile hydrothermal approach and investigated as anode material for LIBs. The time-dependent reaction kinetics of this MOF were investigated to optimize MOF as anode material. The Co(BDC)TED0.5@24h exhibits good rate capability (614 and 239 mAh g−1 at 0.2 and 2.0 A g−1, respectively) with excellent cyclic stability, which is up to 808.2 mAh g−1 after 1000 charge/discharge cycles at 1.0 A g−1 current density. Such an impressive lithium performance is mainly due to channels provided by a pillared-layer framework which not only provides the space for insertion/extraction of Li+ ions but also mitigates the volume expansion during the cycles. The electrochemical process of Co(BDC)TED0.5@24h electrode is elucidated by in-depth series of ex-situ XRD, FTIR, and XPS studies at different charge/discharge states which anticipates the intercalation as working mechanism for Co(BDC)TED0.5. The DFT calculation is also utilized to further confirm the potential binding sites responsible for electrochemical behavior of Co(BDC)TED0.5 as anode materials for LIBs.

The facile synthesis of dialkylthio substituted benzo[1,2-b:4,5-b′]difuran unit via a straightforward palladium-catalyzed carbon–sulfur bond formation reaction is reported. A novel donor–acceptor alternating copolymer was further developed by Stille coupling. The optical and electrochemical properties of the polymer have been carefully studied. The photovoltaic performance by blending the copolymer with [6,6]-phenyl-C71-butyric acid methyl ester were explored in both conventional and inverted solar cell devices. Solvent additive and vapor treatment exhibit positive effects on the device performance. The best devices delivered a power conversion efficiency of 5.48%, with an active layer processed from chloroform solutions with 1,8-diiodooctane (3%) and 30 s tetrahydrofuran vapor treatment.

A new fluorescein derivative, namely, (E)-2-(((1H-pyrrol-2-yl) methylene)amino)-3′,6′-dihydroxyspiro[isoindoline-1,9′-xanthen]-3-one (FLPY), was designed, synthesized, and structurally characterized to develop a chemosensor. The interactions of FLPY with different metal ions have been studied over UV–vis absorption spectra and fluorescent spectra. The results show that FLPY exhibits high sensitivity and selectivity toward Cu2+ among many other metal cations in a DMSO/HEPES (3:1, v/v, 1 mM, pH 7.2) solution. The binding association constant (Ka) of FLPY for Cu2+ based on a 1:1 stoichiometry was estimated to be 1.29 × 104 M−1 in the solution. The detection limit of Cu2+ by FLPY was further determined to be 0.296 μM.

Four isostructural donor-acceptor alternating polymers of benzodithiophene (BDT)/naphthodifuran (NDF) and benzoselenadiazole (BSe)/benzothiadiazole (BT) have been developed and evaluated for organic photovoltaics. The substitution of one-atom (Se for S) in the accepting units exerts remarkable impact on the optoelectronic properties of polymers. Extended absorption, narrowed bandgap and higher HOMO energy levels were observed for Se-containing polymers in comparison to their S-containing counterparts. Theoretical calculations confirmed the measurable effect on energy levels as found in experimental studies. Bulk-heterojuction solar cells based on the BDT-BSe copolymer and [6,6]-phenyl-C71-butyric acid methyl ester (1 : 2, w/w) blend films deliver the best PCE of 5.40%. BSe-based polymers showed enhanced photovoltaic performances than BT-based polymers. The device performance is found to be strongly dependent on the processing conditions and morphology of the active layers.

A new rhodamine spirolactam derivative bearing a thiodiacetamide moiety and two rhodamine B fluorophores (RBTDA) was designed, synthesized and structurally characterized to develop a chemosensor. The interactions of RBTDA with different metal ions have been studied over UV–vis absorption spectra and fluorescent spectra. The results indicated that RBTDA exhibited a highly sensitive and selective turn-on fluorescent response for Cr3+ in the presence of many other metal cations in a methanol-HEPES buffer (3:1, v/v, 0.5 mM, pH 7.25) solution. The binding analysis based on mass spectroscopic data and a Job plot suggested that the RBTDA formed a 1:1 complex with Cr3+. The binding association constant (Ka) for Cr3+ based on a 1:1 stoichiometry was estimated to be 5.01 × 104 M−1 in the solution. The detection limit of Cr3+ by RBTDA was further determined to be 0.378 μM.

An absolute metal-free in-plane heterosystem consisting of g-C3N4 as scaffold and embedded half-metallic C(CN)3 as cocatalysts was conceptually designed for photoconversion of CO2. The no-slot joint between half-metallic C(CN)3 and g-C3N4 through covalent bonding generates a unique two-dimensional, π-conjugated hybrid structure, allowing obstacle-free transferring of the photogenerated electrons in g-C3N4 into C(CN)3 via an intrinsic driving force. Our theoretical calculations together with the in-situ Fourier transform infrared spectra indicate that the most negative charge distribution and binding energy with CO2 for C(CN)3 allow outstanding capture and chemical activation capacity toward CO2, and subsequently enable the optimized heterosystem to exhibit highly efficient and selective photocatalytic reduction of CO2 into CO, 7.8 and 1.9 times those produced with pristine and Pt-modified g-C3N4, respectively. The no-slot joint of organic half-metal cocatalysts with g-C3N4 may open up new opportunities for metal-free, polymer-based photocatalytic systems for CO2 conversion and solar fuel generation.

A newly developed, facile and sustainable self-sacrifice template strategy, in which zinc and chitosan were used as the sacrificial template and carbon source respectively, has been disclosed for the synthesis of a hollow Co-embedded in nitrogen-doped graphite (Co@CN) structure. This material exhibits excellent catalytic efficiency in the oxidative esterification of 5-hydroxymethylfurfural to 2,5-furandicarboxylicacid dimethyl ester that is a significant raw material for polymer synthesis. According to the experimental and calculation results, zinc as the self-sacrificial template and acid-base site regulator has significantly improved the performance of the catalyst. The high specific surface area owing to the partial evaporation of zinc and the optimization of basic and acid sites in the catalyst prove to be the main reasons for its high activity.

The ability to directly detect alkaline phosphatase (ALP) activity in undiluted serum samples is of great importance for clinical diagnosis. In this work, we report the use of the distinctive metal-to-ligand charge-transfer (MLCT) absorption properties of the Cu(BCA)2+ (BCA = bicinchoninic acid) reporter for the visual detection of ALP activity. In the presence of ALP, the substrate ascorbic acid 2-phosphate (AAP) can be enzymatically hydrolyzed to release ascorbic acid (AA), which in turn reduces Cu2+ to Cu+. Subsequently, the complexation of Cu+ with the BCA ligand generates the chromogenic Cu(BCA)2+ reporter, accompanied by a color change of colorless-to-purple of the solution with a sharp absorption band at 562 nm. The underlying MLCT-based mechanism has been demonstrated on the basis of density functional theory (DFT) calculations. Needless of any sequential multistep operations and elaborately designed colorimetric probe, the proposed MLCT-based method allows for a fast and sensitive visual detection of ALP activity within a broad linear range of 20 - 200 mU mL-1 (R2 = 0.999), with a detection limit of 1.25 mU mL-1. The results also indicate that it is highly selective and has great potential for the screening of ALP inhibitors in drug discovery. More importantly, it shows a good analytical performance for the direct detection of the endogenous ALP levels of undiluted human serum samples. Owing to the prominent simplicity and practicability, it is reasonable to conclude that the proposed MLCT-based method has a high application prospect in clinical diagnosis.

A new “turn-on” fluorescent probe, RDMBM , based on the rhodamine B dye and the 2,5-pyrrolidinedione moiety was synthesized and characterized. Its sensing behavior toward various amino acids was evaluated via UV–vis and fluorescence spectroscopic techniques. The observed spectral changes showed that RDMBM displays high selectivity and sensitivity toward GSH in MeOH/H 2 O (1:2, v/v, pH 7.40, Tris-HCl buffer, 1 mM) solution and that it undergoes 1:1 covalent binding with GSH. More importantly, the hydrogenation and ring-opening of the nitrogen atom in the spirane structure of rhodamine B derivatives were tightly bound to the induction effects of different groups. Furthermore, fluorescence imaging applications demonstrated that RDMBM can be successfully used for the detection of GSH in human breast cancer cells MCF-7.

A new strong electron-deficient acceptor unit, 4,9-bis(5-bromothiophen-2-yl)-6,7-bis(5-dodecylthiophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (TQxT), is designed. Three TQxT based new conjugated polymers have been further developed by alternating with benzo[1,2-b:4,5-b′]dithiophene or naphtho[1,2-b:5,6-b′]difuran. Featuring ultra low bandgaps of 1.03–1.10 eV, these polymers exhibit absorption spectra beyond near-infrared (NIR) region. The polymer:PC71BM (1:2) solar cells deliver a best power conversion efficiency (PCE) of 0.43%. The doping of 9 wt% PBDTT-TQxP into P3HT:PC71BM (1:2) blend, however, leads to a highest PCE of 3.58% for the resultant ternary solar cells, corresponding to ∼22% improvement in comparison to 2.93% PCE for P3HT:PC71BM binary cells.

Over the past few decades, bistable [2]rotaxanes have been extensively studied because of their applications in molecular switches. In this paper, a rotaxane molecule containing a dibenzo-24-crown-8 ring and Rhodamine B units was synthesized and characterized by 1 H NMR and HRMS. The Rhodamine B component allows the fluorophore fluorescence to be manipulated in alternate modes by varying the pH of the solution under irradiation. Because of the easy regulation and high sensitivity of the changes in fluorophore fluorescence, Rhodamine B [2]rotaxane can be used as a molecular switch, with different pH values as the input and changes in the fluorescence intensity as the output signals.

A novel rhodamine B-based sensor 1 consisting of a rhodamine B moiety linked to the amine end of a 1,4,7,10-tetraoxa-13-azacyclopentadecane was designed and synthesized. Sensor 1 exhibits a high selectivity for Fe 3+ in the presence of many other metal cations in a MeOH/H 2 O (1:1, v/v, pH = 7.4) solution. The binding analysis using a Job plot suggested that sensor 1 formed a 1:1 complex with Fe 3+ . The Fe 3+ binding ability of 1 was further demonstrated by DFT calculations. Fluorescence microscopy experiments demonstrated that sensor 1 can be used as a fluorescent probe for the detection of Fe 3+ in human liver cells (L-02) and rat neuronal cells (PC12).

A new near-infrared fluorescent probe 1 based on the IR 780 skeleton was designed, synthesized and structurally characterized for the development of a chemosensor. UV-vis absorption and fluorescence spectroscopic studies show that probe 1 exhibits a high selectivity and sensitivity towards iridium(III) in an EtOH/H2O (1:4, v/v, pH 7.4, HEPES buffer, 1 mM) solution by forming a 1:1 complex with iridium(III). Experimental results further demonstrate that the probe 1–iridium(III) complex also has excellent application for the highly selective detection of glutathione.

Simple and fast detection of alkaline phosphatase (ALP) activity is of great importance for diagnostic and analytical applications. In this work, we report a turn-off approach for the real-time detection of ALP activity on the basis of the charge transfer induced fluorescence quenching of the Cu(BCDS)22- (BCDS = bathocuproine disulfonate) probe. Initially, ALP can enzymatically hydrolyze the substrate ascorbic acid 2-phosphate to release ascorbic acid (AA). Subsequently, the AA-mediated reduction of the Cu(BCDS)22- probe, which displays an intense photoluminescence band at the wavelength of 402nm, leads to the static quenching of fluorescence of the probe as a result of charge transfer. The underlying mechanism of the fluorescence quenching was demonstrated by quantum mechanical calculations. The Cu(BCDS)22- probe features a large Stokes shift (86nm) and is highly immune to photo bleaching. In addition, this approach is free of elaborately designed fluorescent probes and allows the detection of ALP activity in a real-time manner. Under optimal conditions, it provides a fast and sensitive detection of ALP activity within the dynamic range of 0-220mUmL-1, with a detection limit down to 0.27mUmL-1. Results demonstrate that it is highly selective, and applicable to the screening of ALP inhibitors in drug discovery. More importantly, it shows a good analytical performance for the direct detection of the endogenous ALP levels of undiluted human serum and even whole blood samples. Therefore, the proposed charge transfer based approach has great potential in diagnostic and analytical applications.

A novel cationic cyclodextrin, mono-6(A)-(2-hydroxyethyl-1-ammonium)-6(A)-β-cyclodextrin chloride (HEtAMCD) has been successfully synthesized and applied as chiral selector in capillary electrophoresis. The NMR study revealed this chiral selector has three recognition sites: β-CD, ammonium cation and hydroxy group in the sidearm to contribute three corresponding driving forces including inclusion complexation, electrostatic interaction and hydrogen bonding. The effect of buffer pH and HEtAMCD concentration (2.5-10 mM) on enantioselectivity, chiral resolution as well as effective mobility of analytes was investigated. This elegantly designed CD exhibits outstanding enantioselectivities toward the studied hydroxyl acids and ampholytic racemates in CE with the aid of extra hydrogen bonding. Under optimum pH 6.0, chiral resolutions over 5 can be readily obtained for hydroxy acids with CD concentration below 5mM. The comparison study between HEtAMCD and our earlier reported ammonium CDs indicates the hydroxyethylammonium group of HEtAMCD significantly increased the enantioselective capability.

Density functional theory (DFT) calculations were performed for the adsorption of hexacyclic C6H6, C6H8, C6H10, and C6H12 molecules/radicals on the Mo-terminated α-Mo2C (100) surface. A cluster model, Mo38C19, was used to simulate the finite surface of an ultradispersed α-Mo2C catalyst. On adsorption, benzene retains a flat geometry, predominantly on the 3-fold hollow sites with 30 degree orientation between the C–C bond of benzene and the Mo–Mo bond of the catalyst. C6H8 also sits flat on the surface, binding strongly with it. However, the stabilization energy shows that it is unstable on the surface and tends to be further hydrogenated or decomposes before desorption. C6H10, on the contrary, binds less strongly to the surface but shows a relatively higher stability on the surface. C6H12 binds very loosely with the surface but showed high stability, indicating a high preference for desorption.

We report a versatile approach for the colorimetric assay of alkaline phosphatase (ALP) activity based on the distinctive metal-to-ligand charge-transfer (MLCT) absorption properties of Fe(II)-phenanthroline reporter. In the presence of ALP, the applied substrate ascorbic acid 2-phosphate is enzymatically hydrolyzed to produce ascorbic acid, which then reduces Fe3+ to Fe2+. The complexation of Fe2+ with the bathophenanthroline disulfonate (BPS) ligand generates a blood-red Fe(BPS)34− reporter, which is characterized by an intense MLCT absorption band at 535 nm in the visible range. Under optimal conditions, the spectral output exhibits a good quantitative relationship with ALP activity over the range of 0–220 mU mL−1 with a detection limit of 0.94 mU mL−1. Moreover, the activity of ALP can also be conveniently judged through naked-eye observations. Results indicate that it is highly selective and can be applied to the screening of ALP inhibitors. In addition, it has been successfully employed to detect the endogenous ALP level of undiluted human serum samples, with a detection limit of 1.05 mU mL−1 being achieved. This approach avoids any elaborately designed substrates and holds considerable simplicity and flexibility for reporter design. This study broadens the horizon of the applications of phenanthroline-based transition metal complexes. Furthermore, an efficient and practical method like this has the potential to be widely used in clinical applications and in the point-of-care testing.

The activity detection of acid phosphatase (ACP) and alkaline phosphatase (ALP) is of great importance to the diagnosis and prognosis of related diseases. In this work, we report for the first time a turn-on colorimetric platform for the activity detection of ACP and ALP, by exploiting Cu(BCDS)22- (BCDS = bathocuproinedisulfonate) as the probe. The presence of ACP or ALP dephosphorylates the substrate ascorbic acid 2-phosphate to produce ascorbic acid, which then reduces Cu(BCDS)22- into Cu(BCDS)23-, leading to a turn-on spectral absorption at 484 nm and a dramatic color change of the solution from colorless to orange-red. The underlying metal-to-ligand charge-transfer mechanism has been demonstrated by quantum mechanical computations. This platform allows a rapid, sensitive readout of ACP and ALP activities within the dynamic range from 0 to 220 mU mL-1. In addition, it is highly immune to false-positive results and also highly selective. More importantly, it is applicable in the presence of human serum and even whole blood samples. These results demonstrate that our platform holds great potential in clinical practices and in the point-of-care analysis.

Molybdenum carbide (Mo2C) is a valuable industrial catalyst for hydrogenation (HYD) of aromatic compounds—an essential step in in-situ heavy-oil upgrading. Despite the intensive studies on catalytic properties of molybdenum carbides, the basic mechanism of HYD reactions occurring on the surface of Mo2C remains vague. We studied the adsorption of benzene on an α-Mo2C(0001) surface at 0.25-mL coverage with first-principles density functional theory (DFT) calculations to provide further insight into the catalytic mechanism. Five high-symmetry adsorption sites combined with two different orientations of the aromatic ring parallel to the surface were investigated at the GGA-PBE level of DFT. Our results suggest that hollow sites are preferred over bridge sites. For the most favorable adsorption sites, i.e., Hc and Vc, the adsorption energy is ca. −2.5 eV. In addition, DFT-D2 calculations were carried out to incorporate the effect of dispersion. Consequently, the adsorption energies at various sites increased by ca. −1.3 eV in general, while the adsorption geometries were little affected. Analysis of the optimized adsorption geometries and the partial density of states revealed a strong interaction between the aromatic ring of benzene and the Mo2C surface, which leads to the rehybridization of benzene carbon atoms, from sp 2 to sp 3.

Although various groups have studied the phosphorylation mechanism of the insulin receptor tyrosine kinase (IRK), an unanimous picture has not yet emerged. In this work, we performed a computational study to gain further insights. We first built a structural model of the reactant complex with the guide of several crystal structures and previous computational studies of the cyclic AMP-dependent protein kinase. We then optimized the structure by performing geometry optimization using a quantum mechanical model containing nearly 300 atoms. A reaction path was then traced between the reactant and the product by using a multiple coordinate-driven method. The calculations mapped out a sequence of structural changes depicting the conversion of the reactant to the product. Analysis of the structural changes revealed the formation of a dissociative transition state and the involvement of a proton transfer from the hydroxyl group of the tyrosyl residue of the peptide substrate to a conserved aspartate in the active site of the enzyme. The proton transfer began well before the transition state was reached and finished only shortly before the product was completely formed. In addition, the formation of a hydrogen bonding network among Arg1136, Asp1132, the gamma-phosphate of ATP, and the tyrosine residue of the substrate appeared to hold the latter two in a near-attack position for reaction. The model estimated a reaction barrier of 14 kcal/mol, semiquantitatively in accord with experiment.

We propose a new density functional for the evaluation of the total electronic energy by subtracting the Roothaan energy, i.e. the Hartree energy of the density residual, from the Hohenberg-Kohn-Sham (HKS) functional, which is normally used in self-consistent Kohn-Sham (KS) density functional theory (DFT) calculations. Because of the positive semi-definite nature of the Roothaan energy, the resulting Wang-Zhou (WZ) functional always produces a total energy lower than that from the HKS functional and usually converges to the exact total energy from below. Following the same spirit of the Zhou-Wang-λ (ZWλ) functional in the recently proposed orbital-corrected orbital-free (OO) DFT method (Zhou and Wang, J Chem Phys 2006, 124, 081107), we linearly mix the WZ functional with the HKS functional to allow further systematic error cancellations. The resulting Wang-Zhou-α (WZα) functional is compared with the ZWλ functional in OO-DFT calculations for systems within different chemical environment. We find that the optimal value of α for the WZα functional is more stable than that of λ for the ZWλ functional. This is because the WZ functional remedies the oscillatory convergence behavior of the Harris functional and renders the direct evaluation of α for the WZα functional more plausible in the application of the linear-scaling OO-DFT method for large systems. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem 107: 2995-3000, 2007

The major challenges of current drug delivery systems for combination chemotherapy focus on how to efficiently transport drugs to target sites and release multiple drugs in a programmed manner. Herein, we report a novel multidrug delivery system, MSNPs 1, based on mechanized silica nanoparticles, which were constructed through functionalization of mesoporous silica nanoparticles with the acid-cleavable intermediate linkages and the monoferrocene functionalized β-cyclodextrin (Fc-β-CD) as supramolecular nanovalves. MSNPs 1 achieved zero premature release in the physiological pH solution and realized two different release modalities. In modality 1, MSNPs 1 released the encapsulated drugs gemcitabine (GEM) and doxorubicin (DOX) in sequence when they were successively applied to voltage and acid stimuli. The release time and dosage of GEM were precisely controlled via external voltage. The subsequent acid-triggered release of DOX was attributed to breakage of the intermediate linkages containing ketal groups. Modality 2 is the concurrent release of these two drugs directly upon acid exposure. Furthermore, the cell viability experiments demonstrated that MSNPs 1 had an improved cytotoxicity to MCF7 cells in comparison with single DOX- or GEM-loaded mechanized silica nanoparticles. We envisage that MSNPs 1 will play an important role in research and development for a new generation of controlled-release drug delivery system.

The separation of racemic molecules is of crucial significance not only for fundamental research but also for technical application. Enantiomers remain challenging to be separated owing to their identical physical and chemical properties in achiral environments. Chromatographic techniques employing chiral stationary phases (CSPs) have been developed as powerful tools for the chiral analysis and preparation of pure enantiomers, most of which are of biological and pharmaceutical interests. Here we report our efforts in developing high-performance phenylcarbamated cyclodextrin (CD) clicked CSPs. Insights on the impact of CD functionalities in structure design are provided. High-efficiency enantioseparation of a range of aryl alcohols and flavanoids with resolution values (Rs) over 10 were demonstrated by per(3-chloro-4-methyl)phenylcarbamated CD clicked CSP. Comparison study and molecular simulations suggest the improved enantioselectivity was attributed to higher interactions energy difference between the complexes of enantiomers and CSPs with phenylcarbamated CD bearing 3-chloro and 4-methyl functionalities.

This chapter presents multi-scale models of the reactions that occur in the in situ oil sands upgrading process. Its focus is on the various modelling tools and their applications to the benzene hydrogenation reactions catalyzed by molybdenum carbide nanoparticles. As the reaction mechanism of benzene hydrogenation on molybdenum carbide is not clear, we start with density functional theory (DFT) studies to elucidate the reaction mechanism, using both periodic and cluster models. Benzene hydrogenation on molybdenum carbide follows the Langmuir-Hinshelwood mechanism, with the six-member ring tilting up gradually. A tight-binding quantum chemical molecular dynamics (TB-QCMD) method is used to track the physical motion of the atoms in the reaction processes of C6H6 on a Mo-terminated α-Mo2C (0001) surface. The approximate DFT method, density functional tight-binding (DFTB), was parameterized to allow the quantum mechanical treatment of nanoscale systems. With the nudged elastic band method, the potential energy profiles of benzene hydrogenation on molybdenum carbide nanoparticles have been obtained. Finally a force field was brought in to describe the solvent environment in the system, leading to a multiscale quantum mechanical/molecular mechanical (QM/MM) model. This study suggests that entropy and the environment play important roles in heterogeneous reactions catalyzed by molybdenum carbide nanoparticles.

A new Rhodamine B derivative (RBDPA), namely, N1-(2-(3′,6′-bis(diethylamino)-3-oxospiro[isoindoline-1,9′-xanthen]-2-yl)ethyl)-N4,N4-bis(pyridin-2-ylmethyl)succinamide, was designed, synthesized and structurally characterized to develop a chemosensor. The studies show that RBDPA exhibits high sensitivity and selectivity toward Al3+ among many other metal cations in an ethanol/H2O (1:1, v/v, pH = 7.2, HEPES buffer, 0.1 mM) solution. Fluorescence microscopy experiments further demonstrate that RBDPA can be used as a fluorescent probe to detect Al3+ in living cells.

A new fluorescent chemosensor based on a Rhodamine B and pyrrole conjugate ( RBPY ) has been designed and synthesized. UV–vis absorption and fluorescence spectroscopic studies show that RBPY exhibits a high selectivity and sensitivity toward Fe 3+ among many other metal cations in a MeOH/H 2 O solution (3:2, v/v, pH 7.10, HEPES buffer, 0.1 mM) by forming a 1:1 complex with Fe 3+ . Furthermore, results reveal that the formation of the RBPY –Fe 3+ complex is fully reversible in the presence of sulfide anions and could also be used as an efficient sensor for S 2− . Importantly, fluorescence microscopy experiments further demonstrated that RBPY can be utilized as a fluorescent probe for the detection of Fe 3+ in human liver (L-02) cells.

A new fluorescent chemosensor based on a Rhodamine B and a benzyl 3-aminopropanoate conjugate (RBAP) was designed, synthesized, and structurally characterized. Its single crystal structure was obtained and analyzed by X-ray analysis. In a MeOH/H2O (2:3, v/v, pH 5.95) solution RBAP exhibits a high selectivity and excellent sensitivity for Sn2+ ions in the presence of many other metal cations. The binding analysis using the Job’s plot suggested the RBAP formed a 1:1 complex with Sn2+.

This paper presents a stochastic resonance occurring in a chemical reaction Pt(100)/NO+CO. The results were from numerical simulation of the nonlinear kinetic behavior of a three-variable reaction model obtained from the law of mass actions. The model exhibits a special region in the bifurcation scheme, where a stable node coexists with a stable limit cycle. When one of the control parameters is perturbed by a weak, low frequency periodic signal riding on a suitable external noisy background, transitions between the steady state and oscillatory state may become regular unexpectedly, and signal to noise ratio is thus enhanced at the signal frequency in the Fourier transform power spectrum of the time series output. That refers to stochastic resonance, in which the noise may play a constructive role in the detection of weak signals. The findings may suggest a new method to develop chemical sensitive devices in the field of applications. The paper also discusses the conditions of occurrence of stochastic res...

We have developed a method to improve the description of solute cavity defined by the interlocking-sphere model for continuum-solvent electrostatics calculations. Many models choose atomic radii from a finite set of atom types or uses an even smaller set developed by Bondi [J. Phys. Chem. 68, 441 (1964)]. The new model presented here allowed each atom to adapt its radius according to its chemical environment. This was achieved by first approximating the electron density of a molecule by a superposition of atom-centered spherical Gaussian functions. The parameters of the Gaussian functions were then determined by optimizing a function that minimized the difference between the properties from the model and those from ab initio quantum calculations. These properties included the electrostatics potential on molecular surface and the electron density within the core of each atom. The size of each atom was then determined by finding the radius at which the electron density associated with the atom fell to a prechosen value. This value was different for different chemical elements and was chosen such that the averaged radius for each chemical element in a training set of molecules matched its Bondi radius. Thus, our model utilized only a few adjustable parameters—the above density cutoff values for different chemical elements—but had the flexibility of allowing every atom to adapt its radius according to its chemical environment. This variable-radii model gave better solvation energy for 31 small neutral molecules than the Bondi radii did, especially for a quantum mechanics∕Poisson–Boltzmann approach we developed earlier. The improvement was most significant for molecules with large dipole moment. Future directions for further improvement are also discussed.

Orbital-free density-functional theory (OF-DFT) with modern kinetic-energy density functionals (KEDFs) is a linear scaling technique that accurately describes nearly-free-electron-like (main group) metals. In an attempt towards extending OF-DFT to transition metals, here we consider whether OF-DFT can be used effectively to study Ag, a metal with a localized d shell. OF-DFT has two approximations: use of a KEDF and local pseudopotentials (LPSs). This paper reports construction of a reasonably accurate LPS for Ag by means of inversion of the Kohn-Sham (KS) DFT equations in a bulk crystal environment. The accuracy of this LPS is determined within KS-DFT (where the exact noninteracting kinetic energy is employed) by comparing its predictions of bulk properties to those obtained from a conventional (orbital-based) nonlocal pseudopotential (NLPS). We find that the static bulk properties of fcc and hcp Ag predicted within KS-DFT using this LPS compare fairly well to those predicted by an NLPS. With the transferability of the LPS established, we then use this LPS in OF-DFT, where several approximate KEDFs were tested. We find that a combination of the Thomas-Fermi (T(TF)) and von Weizsacker (T(vW)) functionals (T(vW)+0.4T(TF)) produces better densities than those from the linear-response-based Wang-Teter KEDF. However, the equations of state obtained from both KEDFs in OF-DFT contain unacceptably large errors. The lack of accurate KEDFs remains the final barrier to extending OF-DFT to treat transition metals.