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Three new lead(II) complexes containing the 1,10-phenanthroline ligand, [Pb(phen)2(3,5-DNB)2] (1), [Pb(phen)2(3,5-DNB)(NO3)]2·H2O (2), and [Pb(phen)(HCOO)(NO3)(H2O)] n (3) (phen = 1,10-phenanthroline, 3,5-DNB = 3,5-dinitrobenzoate anion) have been synthesized and characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses (TGA), and single-crystal X-ray diffraction. The complexes 1 and 2 are monomeric species, whereas complex 3 is a one-dimensional polymer. In the three complexes, the ligand phen creates a number of π···π stacking interactions and hydrogen bonds, which play an important role in extending complexes 1–3 to supramolecular architectures. The Pb(II) ion of complexes 1 and 2 shows hemidirected geometry with noncovalent Pb···O/C tetrel bonds formed which further stabilize the supramolecular structures.

Herein, chiral Brønsted acid-catalyzed intramolecular asymmetric allylic alkylation of indoles with allylic primary alcohols is described. The allyl alcohols were directly employed as the allylic precursors in this metal-free protocol, without preactivation or any additional activating reagents. This method provides the convenient synthesis of a broad range of functionalized tetrahydrocarbazoles in excellent yields (≤97%) with good enantioselectivity (≤93% ee). The optimal conditions are compatible for gram-scale reaction.

An efficient synthesis of methylene-unsubstituted cyclopropane-fused indolines via photoredox catalyzed dearomative cyclopropanation of indole derivatives was developed.

Dearomatization reactions provide rapid access to structurally complex three-dimensional molecules from simple aromatic compounds. Plenty of reports have demonstrated their utilities in the synthesis of natural products, medicinal chemistry, and materials science in the last decades. Recently, visible-light mediated photocatalysis has emerged as a powerful tool to promote many kinds of transformations. The dearomatization reactions induced by visible-light have also made significant progress during the past several years. This review provides an overview of visible-light induced dearomatization reactions classified based on the manner in which aromaticity is disrupted.

An iridium-catalyzed asymmetric allylic benzylation of aryl vinyl carbinols under light irradiation is described. 2-Methylbenzophenone derivatives are employed and activated to hydroxy-o-quinodimethanes by an ultraviolet (UV) light. This approach enables asymmetric allylic benzylation with high enantioselectivity (up to 99 % ee) from readily available 2-methylbenzophenones without the utilization of strong bases, and pre-activation or pre-functionalization of the substrates. Moreover, deuterium experiments reveal the generation of nucleophilic benzyl species from 2-methylbenzophenone under UV irradiation.

The complex [Pb(phen)(4-NB)(CH3COO)] of lead(II) was prepared and characterized by means of elemental analysis, FT-IR, and single crystal X-ray analysis, where phen = 1,10-phenanthroline, 4-NB = 4-nitrobenzoate. The single crystal X-ray analysis indicates that the complex is a monomeric species, including two carboxylate ligands, and adopts a hemidirected structure. It is further extended by intermolecular C−H⋯O hydrogen bonds, π–π interactions and secondary Pb⋯O interactions to form two-dimensional supramolecular architecture.

A photocatalytic protocol for the divergent dearomative functionalization of indole derivatives is reported. Under the irradiation of visible light, either dimerization or reduction occurs selectively by modifying the reaction conditions, leading to the formation of the corresponding cyclobutane-fused polycycles and 2-substituted indolines in good yields with exclusive selectivity.

A new Pb(II) complex, [Pb(8-OQ)(4-NB)], where 8-OQ = 8-hydroxyquinolinate, 4-NB = 4-nitrobenzoate, has been synthesized and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. The single crystal X-ray analysis reveals that the complex possesses a tetranuclear Pb4O4 cubane structure. The Pb(II) atom is coordinated by three triply bridging phenolic hydroxyl O atoms of 8-OQ ligands, then the tetranuclear Pb system is formed resulting in a tetrahedral cage. The interaction of complex with HS-DNA in Tris buffer was studied by UV−vis absorption spectrum and fluorescence ethidium bromide displacement experiment with an intrinsic binding constant of 1.52×104 M-1 and a linear Stern–Volmer quenching constant of 6.77×103 M-1. Anticancer activity against MCF-7, HepG-2 and A549 cell lines of complex was also determined by the MTT-based assay. The results showed the complex can inhibit proliferation of these three kinds of tumor cells and is less cytotoxic than cisplatin.

Herein, we explore a new carbon source for preparation of carbon quantum dots (CQDs) with controllable composition using a porous organic polymer (POP) derived porous carbon via a nitric acid oxidation method. The POP used for the preparation of CQDs was synthesized by mechanochemical Friedel–Crafts alkylation under solvent free conditions. Using the as-prepared CQDs, we develop a simple and effective electrochemiluminescence (ECL) detection method for dopamine (DA) using a CQD/chitosan–graphene composite modified glassy carbon electrode (GCE). Both the electrochemical and ECL behaviors were studied in detail with ammonium persulfate as a coreactant. The complementary structure and synergistic function of the composite give the ECL sensor special properties. Apart from the high stability, it also presents good repeatability and high sensitivity to DA with a wide linear range from 0.06 to 1.6 μM. And a satisfactory detection limit of 0.028 μM (S/N = 3) was achieved for the prepared sensor. Furthermore, the ECL also shows high selectivity toward DA with an excellent interference resistance ability at a high concentration ratio of 100 (Cinterference : CDA = 100). In addition, the ECL sensor was successfully applied for effective detection and quantitative analysis of the actual dopamine in human body fluids for disease diagnosis and pathological studies.

Here is reported the novel determination of hydrogen peroxide by electrochemiluminescence using a chitosan–graphene composite film doped cadmium-tellurium quantum dot modified glassy carbon electrode. The cadmium-tellurium quantum dots were studied by absorption and fluorescence spectroscopy. Scanning electron microscopy and electrochemical impedance spectroscopy were used to characterize the structure morphology of the composite matrix. The electrochemiluminescence emission was linear with the concentration of hydrogen peroxide in the range of 3.5 × 10−7 to 1.1 × 10−5 M with a determination limit of 2.1 × 10−7 M. Furthermore, the modified electrode showed excellent reproducibility and stability.

Dearomatization of indoles provides efficient synthetic routes for substituted indolines. In most cases, indoles serve as nucleophiles. Reported here is an asymmetric dearomatization reaction of indole derivatives that function as electrophiles. The combination of a photocatalyst and chiral phosphoric acid open to air unlocks the umpolung reactivity of indoles, enabling their dearomatization with N-hydroxycarbamates as nucleophiles. A variety of fused indolines bearing intriguing oxy-amines were constructed in excellent yields with moderate to high enantioselectivities. Mechanistic studies show that the realization of two sequential single-electron transfer oxidations of the indole derivatives is key, generating the configurationally biased carbocation species while providing the source of stereochemical induction. These results not only provide an efficient synthesis of enantioenriched indoline derivatives, but also offer a novel strategy for further designing asymmetric dearomatization reactions.

Three new complexes, {[Mn(2,2′-bipy)(4,4′-bipy)0.5(4-sb)(H2O)](H2O)2}n (1), [Mn(phen)2(4-sb)(H2O)](4,4′-bipy)0.5(H2O)3 (2), and [Fe2(phen)6](4-Hsb)(H2O)5 (3) [4-sb = 4-sulfobenzoate dianion, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, phen = 1,10-phenanthroline], have been synthesized and structurally characterized. The interaction of complex with HS-DNA was investigated by carrying out UV−vis absorption spectrum and fluorescence ethidium bromide displacement experiment. The DNA-binding constants Kb of complexes 1, 2, and 3 were calculated to be 7.39 × 105 M−1, 3.94 × 105 M−1, and 9.34 × 105 M−1, respectively. The results indicated that these complexes interact with HS-DNA through intercalative mode. Competitive studies with ethidium bromide (EB) further showed that the complexes bind to DNA probably via intercalation. The complexes were tested for antiproliferative activities on a panel of cell lines (MCF-7, HepG-2, A549, BGC823, and HTR-8) by MTT method, three complexes can inhibit the tumor cell proliferation, but complex 1 is less cytotoxic than other two complexes. The apoptosis assay was assessed with the Annexin-V/PI double staining methods and the results revealed that complexes induced the HepG-2 cells apoptosis.

An intermolecular oxidative dearomatization of β-naphthols with N-hydroxycarbamates promoted by visible light was realized by means of photogenerated β-naphthol radical cation intermediates. With a commercially available organic dye, the naphthalenones bearing a fully substituted stereogenic center were obtained with up to 92 % yield under aerobic conditions (26 examples). In addition, the rearrangement of C-O coupling products to C-N coupling compounds could be achieved merely in the presence of Cs2 CO3 . This transformation simultaneously provides an attractive and synthetically useful approach to access the aminative dearomatization compounds.

Immobilized antibodies with oriented and homogeneous patterns are crucial to solid-phase molecular recognition assay. Antibody binding protein-based immobilization can effectively present the desired antibodies. However, steadily installing the stromatoid protein with site-specific attachment manner onto a matrix surface remains to be elucidated. In this study, we present an optimal protocol to tightly attach an immunoglobulin G (IgG)-binding protein (Z-domain) through covalent incorporation of Cys-tag and maleimide group onto polystyrene surface to guarantee site-specific, oriented, and irreversible attachment, resulting in a highly efficient platform for three-dimensional IgG immobilization. The actual IgG-binding characteristic of immobilized Z-Cys was investigated by employing affinity chromatography and size exclusion chromatography. And the efficacy and potential of this platform was demonstrated by applying it to the analysis of interaction between rabbit anti-HRP IgG and its binding partner HRP. The proposed approach may be an attractive strategy to construct high performance antibody arrays and biosensors given that the antibody is compatible with the Z-domain.

Thermosensitive hydrogels have increasingly received considerable attention for local drug delivery based on many advantages. However, burst release of drugs is becoming a critical challenge when the hydrogels are employed. Microspheres- (MS-) loaded thermosensitive hydrogels were thus fabricated to address this limitation. Employing an orthogonal design, the spray-dried operations of tenofovir (TFV)/Bletilla striata polysaccharide (BSP)/chitosan (CTS) MS were optimized according to the drug loading (DL). The physicochemical properties of the optimal MS (MS F) were characterized. Depending on the gelation temperature and gelating time, the optimal CTS-sodium alginate- (SA-) α,β-glycerophosphate (GP) (CTS-SA-GP) hydrogel was obtained. Observed by scanning electron microscope (SEM), TFV/BSP/CTS MS were successfully encapsulated in CTS-SA-GP. In vitro releasing demonstrated that MS F-CTS-SA-GP retained desirable in vitro sustained-release characteristics as a vaginal delivery system. Bioadhesion measurement showed that MS-CTS-SA-GP exhibited the highest mucoadhesive strength. Collectively, MS-CTS-SA-GP holds great promise for topical applications as a sustained-release vaginal drug delivery system.

A new one-dimensional (1D) coordination polymer, [Pb2(psa)(phen)2(NO3)2]n, has been synthesized by the method of hydrothermal reaction and characterized by elemental analysis, FT-IR and X-ray single-crystal diffraction (where H2psa is phenylsuccinic acid and phen is 1,10-phenanthroline). The single-crystal X-ray analysis showed that the complex has a dinuclear core stabilized by bridging phenylsuccinic acids and nitrate anions. The coordination number of the two Pb(II) atoms are 7 and 6, with the stereochemically active lone pair, resulting in the hemidirected geometry for the complex. The complex contain a 1D chain, which is further extended into two-dimensional supramolecular architecture through hydrogen bonds, C-H···π, and π···π interactions.

Based on molecular mechanics and the stick-spiral model, this paper first presents the analytical analysis of the effective in-plane mechanical properties of both zigzag and armchair monolayer graphene sheets. We find that the equivalent in-plane elastic constants of monolayer graphene sheets are the same in the two principal directions of graphene. The effective in-plane mechanical properties of graphene are then evaluated numerically using an improved molecular structural mechanics (MSM) model, in which the flexible connections are used to characterize the bond angle variations of graphene. Furthermore, the effective bending rigidity of the beam representing a C-C bond in this improved MSM model is determined from the energy equivalence over the basic cell of graphene and the force constants given by molecular mechanics. A rigidly connected frame model with the bending stiffness of the equivalent beams for C-C bonds different from the existing structural mechanics model is also used to evaluate the mechanical properties of graphene. The flexibly connected frame model gives very good results of Youngs modulus and Poisson ratio of monolayer graphene sheet. The new rigidly connected frame model presented here also gives improved results than the existing rigidly connected frame model of graphene.

Two new lead (II) complexes, {(Pb(4-abs)(4,4 � -bipy)2 (H2O)3)·(4-abs)}n (1) and (Pb(4-abs)2(phen)2 (H2O)) (2), have been synthesized and characterized by elemental analyses, FTIR, thermal analyses, fluorescent spectra, and single-crystal X-ray analyses, where 4-abs is 4-aminobenzenesulfonate anion, 4,4 � -bipy is 4,4 � -bipyridine, phen is 1,10-phenanthroline. In these two complexes 4-abs shows three different modes, in complex 1 4-abs plays two roles: One serves as a bridging ligand, another is deprotonated and does not coordinate to the Pb atom, in complex 2 the 4-abs is a monodentate ligand. The structure of complex 1 is a one-dimensional polymer, whereas complex 2 is monomeric species. Intermolecular π-π interactions and hydrogen bonds are observed in these two complexes, which stabilize the crystal packing and give rise to supramolecular architectures.

A new lead complex, {[Pb(4-sb)(phen)](4,4′-bipy)0.5}n (1) (where 4-sb=4-sulfobenzoate dianion, phen=1,10-phenanthroline, 4,4′-bipy=4,4′-bipyridine), was synthesized and characterized by single-crystal X-ray, infrared, and thermogravimetric analyses and fluorescence studies. In this compound, the lead atom is hexacoordinated by two N atoms of one phen ligand and four O atoms from three 4-sb dianions. Each 4-sb serves as a bridging ligand, connecting adjacent PbII atoms into a centrosymmetric polymeric chain. Intermolecular π-π interactions and hydrogen bonds are observed in the complex, which stabilize the crystal packing and give rise to three-dimensional architecture.

Highly efficient protein immobilization is extremely crucial for solid-phase immunoassays. We present a strategy for oriented immobilization of functionally intact immunoglobulin G (IgG) on a polystyrene microtiter plate via iminodiacetic acid (IDA)-Ni(2+) and ZZ-His protein interaction. We immobilized a ZZ-EAP (Escherichia coli alkaline phosphatase)-His fusion protein, which exhibits Fc binding, His tag, and intrinsic AP activities, and analyzed it against the interaction between rabbit IgG anti-horseradish peroxidase (anti-HRP) and its binding partner HRP to investigate the specificity and efficacy of this method. We compared the IDA-Ni(2+)-(ZZ-His) method with ZZ-EAP random immobilization using sandwich enzyme-linked immunosorbent assay, and the results showed that the former method had an enhanced signal, 10-fold higher sensitivity, and a wider linear range. Thus, the proposed method allows a broad range of oriented immobilized functionally intact IgG antibodies on polystyrene plates using only one type of IDA-Ni(2+) chelate surface because the ZZ protein can bind to the Fc region of various IgGs.

Based on a new molecular structural mechanics model, the effective in-plane mechanical properties of monolayer graphene sheet is analytically analyzed in this paper. The energy equivalence between the basic cell of the atomic structure of graphene and the corresponding basic cell, defined in the homogenization of periodic cellular media, of its equivalent periodic framed structure is used to determine the mechanical properties of the equivalent structural members representing the C-C bonds of graphene. The resulting relationship between the mechanical parameters of the equivalent structural members and the force constants defined in molecular mechanics are different from those used in other molecular structural mechanics models. And these mechanical parameters yield more accurate effective mechanical properties of graphene, especially the Poisson ratio, than the existing molecular structural mechanics models.

In the title compound, [Pb₂(C₇H₄O₆S)₂(C₁₂H₈N₂)₂(H₂O)₂]·CH₃COOH, the seven-coordinate Pb(II) atom is chelated by two N atoms of one 1,10-phenanthroline ligand, four O atoms from three 5-sulfosalicylate dianions and one water O atom. Each dianion serves as a bridging ligand, connecting adjacent Pb(II) atoms into a centrosymmetric polymeric chain extending parallel to [001]. There are π-π inter-actions between the aromatic systems of neighbouring dianions, with plane-to-plane distances of 3.371 (2) Å, and between phenanthroline ligands, with a centroid-to-centroid distance of 3.484 (2) Å. O-H⋯O hydrogen bonding additionally stabilizes the crystal packing. The acetic acid mol-ecules are incorporated in the voids of this arrangement. They exhibit half-occupancy due to disorder around a centre of inversion.

The title compound, [Pb2(C7H5O2)2(NO3)2(C12H8N2)2(H2O)2], crystallizes as a dinuclear centrosymmetric dimer containing two PbIIatoms bridged by two benzoate ligands. Each PbIIatom is seven-coordinated by a water molecule, a nitrate anion, a 1,10-phenanthroline (phen) ligand and two benzoate anions. The crystal packing is stabilized by O—H...O hydrogen bonds and by π–π stacking between neighboring phen ligands, with a centroid–centroid distance of 3.557 (3) Å.