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Based on the measured ICD data and binding constants, the representative binding conformations of β-CD/N-methylcarbamates are identified and the competition between the non-covalent interaction and solvent effect is revealed by a MD/QM/CSM approach.

The acceptor-donor-acceptor structured fused-ring electron acceptors (FREAs) have piqued interest for organic solar cells. We herein employ time-dependent density functional theory to evaluate the effect of Hartree-Fock exact exchange (HFX) on the performance of 16 global hybrid functionals for computing the maximum absorption wavelengths (

Biothiols and hydrogen sulfide, as critical sulfur-containing reactive substances, serve essential functions in various human pathological processes, making it challenging to simultaneously distinguish them due to their similar reactivity and structures (-SH). Here, we rationalized the development of a single-wavelength excitation near-infrared (NIR) fluorescence probe, FC-NBD, for distinguishing GSH/H

A series of 1,3,4-oxadiazole-2-thiol derivatives bearing various alkyl or aryl moieties were designed, synthesized, and characterized using modern spectroscopic methods to yield 17 compounds (6a-6q) that were screened for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes in the search for 'lead' compounds for Alzheimer's disease treatment (AD). The compounds 6q, 6p, 6k, 6o, and 6l showed inhibitory capability against AChE and BChE, with IC

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.

Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi2WO6 crystal lattice via varying content of Ti dopant to fabricate single-unit-cell layered structure, resulting in enhanced visible-light-driven photocatalytic efficiency. Density functional theory (DFT) calculations verified that the substitution of Bi cation in the crystal structure of Bi2WO6 can induce a new defect level, and increase the density of states (DOS) at the valence band maximum, which not only improve the charge dynamic but also the electronic conductivity. Remarkably, the single-unit-cell layers Ti-doped Bi2WO6 structure casts profoundly improved photocatalytic performance towards ceftriaxone sodium degradation, Cr(VI) reduction, and particularly higher photocatalytic H2 production rate, with a 5.8-fold increase compared to bulk Bi2WO6. Furthermore, the photoelectrochemical measurements unveil that the significantly higher charge migration and charge carrier dynamic counts for the elevated photocatalytic performance. After careful examination of experimental results, it was proved that the Ti doping mediated crystal defects, and engendered oxygen vacancies are critically important for controlling the photocatalytic performance of Bi2WO6.

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.

A tandem CuAAC/ring cleavage/[4 + 2] annulation reaction of terminal ynones, sulfonyl azides, and oximes has been developed to synthesize functionalized dihydrooxazines under mild conditions. In particular, intermediate

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 development of big data has added new vitality to the teaching work of colleges and universities. This article mainly discusses the basic concepts and characteristics of big data. Simultaneously, this article also analyzes the main problems in the construction of college informatization teaching mode under the background of big data. Then, this article studies the main modules and construction methods of college informatization teaching mode. By checking the role of big data technology in college informatization teaching, this article aims to promote the practical construction of college informatization teaching mode. Simultaneously, this article provides some valuable help for college teachers.

Bacterial cellulose/hydroxyapatite (BC/HAp) composite is an outstanding candidate for bone tissue engineering. The conventional biomimetic mineralization method takes a long time with unsatisfactory mechanical properties and biocompatibility. Herein, we modified the BC by changing the carbon source to calcium gluconate during the biosynthesis process of BC by bacteria, providing nucleation sites for further mineralization in simulated body fluid. Results show spherical porous HAp in the size of 100-200 nm was fully filled in the three-dimensional network structure of BC nanofibers uniformly within five days of mineralization. Molecular dynamics simulation shows that the aggregation of cellulose units in aqueous solution can enhance the adsorption of calcium ions. By this means, we significantly improved the mechanical properties and biocompatibility of the BC/HAp composite, as well as simplified the preparation process, compared to conventional method, which, therefore, suggests, it could be further studied for biomedical applications such as bone tissue engineering.

Crystal defects are crucially important in semiconductor photocatalysis. To improve the reactivity of photocatalysts and attain desirable solar energy conversion, crystal defect engineering has gained considerable attention in real catalysts. Herein, we engineered crystal defects and mediate oxygen vacancies in host Bi

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.

To maximize the photovoltaic performance of perovskite solar cells (PVSCs）by developing new hole-transport layer (HTL) materials, the precise tuning of their energy levels especially the highest occupied molecular orbital (HOMO) is highly desirable. Here, a simple binary strategy for the first time is proposed to acquire ideal HOMO level by optimizing the composition of binary blend HTLs including CZ-TA (HOMO = −5.170 eV) and CZ-STA (HOMO = −5.333 eV). By adding 10 wt% CZ-STA, the binary HTM (HOMO = −5.199 eV) based perovskite solar cells achieve a maximum power conversion efficiency of 19.85% (18.32% for CZ-TA). The introducing of S atom in CZ-STA not only downshifts HOMO level but also forms stronger Pb-S interaction with perovskites than Pb-O in CZ-TA, leading to better device performance and reduced hysteresis. Importantly, the un-encapsulated PVSCs using CZ-TA:CZ-STA (90:10, w/w) binary HTL exhibit good environment stability in ambient air, maintaining over 82% of their initial efficiency after 60 days’ storage with a relative humidity around 50%. Therefore, this strategy provides new insights on HTL development to push forward the progress of the emerging PVSCs

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.

Three novel small molecules named DR3TDST, DRCN3TDST and DB3TDST containing bisalkylthiothienyl side-chain on benzo[1,2-b:4,5-b']dithiophene (BDT) core with different electron-deficient ending-groups are designed and synthesized. All three molecules have deep HOMO energy level from −5.40 eV to −5.44 eV, indicating introduction of bisalkylthio group to BDT is an effective method to modulate the molecular energy levels. Different ending-groups exhibit small but measurable effects on absorption, energy level, charge transport, morphology, and photovoltaic properties of small molecules. Bulk heterojunction solar cells fabricated with DRCN3TDST and PC71BM deliverer the highest power conversion efficiency (PCE) of 5.17% after annealing and solvent vapor annealing.

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.

Although nitrogen-doped graphene quantum dots (N-doped GQDs) have been widely studied for their unique properties and promising applications, large scale synthesis of N-doped GQDs has been rarely reported. Besides, the formation mechanism was always explained simply. Herein we report a facile one-step gram-scale approach to prepare N-doped GQDs by polymerization of nitrilotriacetic acid (NTA) under high temperature and pressure in a nitrogen environment. A mechanism, which is rooted in the chemical properties of NTA and consists of dehydration and nucleophilic addition, has been proposed to explain the formation of N-doped GQDs step by step. Utilizing this method, the change in the structure, functional groups and FL properties can be explained intuitively and clearly. Because of the significant difference in ethanol solubility between the raw material and product, N-doped GQD powder with a purity higher than 99% can be easily obtained by a dissolution–centrifugation–drying–dissolution–freeze drying process without a tedious dialysis process. 1.38 grams of N-doped GQDs could be prepared from 3 grams of NTA. The 46% synthetic yield is higher than that obtained using a large majority of methods reported so far. With the introduction of an N atom, the N-doped GQDs showed bright blue fluorescence (FL) under 365 nm ultraviolet (UV) light, exhibiting a quite high quantum yield of 45.8%. A short preparation time, the low cost of the raw materials, a simple preparation process, high synthetic yield, high quantum yield and a facile purification method make this approach promising in the industrial production of N-doped GQDs. Besides, the N-doped GQDs were used as handwriting FL ink in the form of aqueous and oil-like ink, and used in a fountain pen and ball pen respectively. The words written with FL ink showed strong contrast under daylight and UV light, and no obvious change can be observed after long-term high temperature treatment, indicating that the N-doped GQDs have obvious practicability and good stability as an FL ink.

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.

Crystal defects have been broadly regarded to modulate the photoreactivity of semiconductors, mostly concerning the crystal and electronic structure of materials. On the other hand, oxygen defect-engineering is a fundamental approach to improve the photolysis activity of materials. Herein, an interactive hybrid intermediate strategy with oxygen defect-engineering was utilized to fabricate atomically-thin Ti-doped Bi2MoO6 nanosheets. Experimental results unveil that the well-engineered ultrathin Ti-doped Bi2MoO6 nanosheets tune the morphology, visible light absorption, local atomic and electronic band structure of Bi2MoO6. Importantly, the Ti-doping hugely affects the BET specific surface area and porosity of Ti-Bi2MoO6 (72 m2 g−1) in contrast to bulk Bi2MoO6, which is 19 m2 g−1. Furthermore, the density functional theory calculations were carried out to explore the effect of Ti-doping on electronic band structure and the surface charge distribution in Ti-Bi2MoO6. It was found, rather than acting as a recombination center for photogenerated charge carriers, the defect caused by Ti doping mediated O vacancies in the crystal structure of Bi2MoO6, which favors the photogenerated charge carriers transfer and enhances the photocatalytic reactivity due to delocalized nature. With the advantages of atomically-thin structure Ti-Bi2MoO6 nanosheets, the synergistic effect of ultrathin thickness of Ti-Bi2MoO6 and oxygen vacancies has remarkably improved the photocatalytic activity towards the degradation of nitrofurantoin, and photoreduction of Cr(VI) in a highly acidic and alkaline medium. The present work opens a door for enhancing the photolysis performance of Bi2MoO6-based photocatalysts with excellent photolysis activity in the various environmental remediation processes.

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.

We demonstrate for the first time how to assemble mechanized hollow zirconia nanospheres (MHzNs), consisting of hollow mesoporous zirconia nanospheres (HMZNs) as nanoscaffolds and supramolecular switches anchored on the exterior surface of HMZNs. The remarkable advantage of substitution of HMZNs for conventional mesoporous silica nanoscaffolds is that HMZNs can suffer the hot alkaline reaction environment, which provides a novel strategy for functionalization and thus achieve dual pH-mediated controlled release functions by simple and practicable assembly procedure. Under neutral solution, cucurbituril[7] (CB[7]) macrocycles complexed with propanone bis(2-aminoethyl)ketal (PBAEK) to form [2]pseudorotaxanes as supramolecular switches, blocking the pore orifices and preventing the undesirable leakage of cargoes. When solution pH was adjusted to alkaline range, CB[7] macrocycles, acting as caps, disassociated from PBAEK stalks and opened the switches due to the dramatic decrease of ion-dipole interactions. While under acidic conditions, PBAEK stalks were broken on account of the cleavage of ketal groups, resulting in the collapse of supramolecular switches and subsequent release of encapsulated cargoes. MHzNs owning dual pH-mediated controlled release characteristic are expected to apply in many fields. In this work, the feasibility of doxorubicin (DOX)-loaded MHzNs as targeted drug delivery systems was evaluated. In vitro cellular studies demonstrate that DOX-loaded MHzNs can be easily taken up by SMMC-7721 cells, can rapidly release DOX intracellularly, and can enhance cytotoxicity against tumor cells, proving their potential for chemotherapy.

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 reaction of dimorpholinomethane in fuming HNO

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.