Selective C–H bond alkynylation toward modular access to material and pharmaceutical molecules is of great desire in modern organic synthesis. Reported herein is Ir(III)-catalyzed regioselective C–H alkynylation of ketones and esters, which is generally applicable for the rapid construction of molecular complexity. This protocol provides a complementary process for conventional alkyne synthesis. Further functionalization of carbonyl-derived material molecules and pharmaceuticals demonstrates the potential synthetic utility of this methodology.

Two Schiff base derivatives (S1 and S2) containing triphenylamine and indole fluorophores groups have been synthesized via a one-pot reaction and utilized as fluorescence turn-off sensors towards Fe3+ ions in THF. S1 and S2 demonstrated fluorescence turn-off sensing towards Fe3+ ions, via photoinduced electron transfer (PET). The 2 : 1 stoichiometries of the sensor complexes ([S1, S2] + Fe3+) were calculated from Job plots based on UV-vis absorption titrations. The detection limits (LODs) of [S1, S2] + Fe3+ sensor responses were calculated by their standard deviation, linear fitting and from their fluorescence binding isotherms. More importantly, [S1, S2] + Fe3+ sensors were found to be active in aqueous media within a wide range of pH values. In addition, biological imaging and membrane permeability demonstrated that S1 could act as a turn-off fluorescence chemosensor for Fe3+ in living cells.

•Novel poly(vinyl alcohols) (PVA) functionalized with covalent pendant zwitterionic group synthesized in a controllable manner.•The appendant zwitterionic group exhibits strong electrostatic interaction.•The attached zwitterion facilitates proton conduction and yet suppresses methanol crossover.A desirable membrane for direct methanol fuel cell (DMFCs) must both conduct protons and function as a methanol barrier. However, it remains challenge to balance the proton conduction and methanol permeability. As a commonly used pervaporation membrane, PVA has high selectivity for water over methanol, but its proton conductivity is too low for DMFCs applications. To improve conductivity, efforts have been predominantly focused on direct incorporation of strongly acidic groups, such as sulfonated or phosphoric groups on the PVA chain. This strategy can result in improvement in the proton conduction. However, the performance of acid modified PVA is compromised due to the strong charge–charge repulsion of attached groups, which results in the increased fraction free volume that facilitates methanol permeation. We attempt to minimize the tradeoff between proton conduction and methanol permeability by modifying PVA with zwitterionic groups. This is achieved by functionalizing PVA with pendent zwitterionic groups (PVA-ZW-n) at controllable substitution degree (5 < n < 20). The investigation of their 1H NMR spectra and glass transition temperatures (Tg) suggests that there is strong electrostatic interaction in the PVA-ZW-20 polymer, as confirmed by the observed proton spatial distribution in NMR, and increased Tg along with the increase of substitution degree in DSC. The synthesized PVA-ZW-20 can be easily casted into mechanically stable membranes with modest proton conductivity. After incorporation with (3-Mercaptopropyl)trimethoxysilane (MPTMS) and successive oxidation, the synthesized PVA-ZW-20-Si exhibits lower methanol permeability and reasonably higher proton conductivity compared to Nafion 117. A series of control experiments revealed that the superior performance of PVA-ZW-20-Si could be related to the presence of zwitterionic groups, which result in enhanced packing density of polymer chain and more efficient proton dissociation.

Five novel soluble chemosensors in EtOH/H2O based on Schiff-base diaminomaleonitrile derivatives which were modified by different aromatic functional moieties have been synthesized. These chemosensors were fully characterized by 1H NMR, 13C NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction. The recognition abilities of these chemosensors with a range of metal ions at different pH values were evaluated and their photophysical properties have been systematically investigated. DFT theoretical calculations were employed to understand the behaviors of the chemosensors toward Hg2+. The sensing mechanism was derived through experimental and theoretical calculations. All the results consistently indicated that these diaminomaleonitrile derivatives were ideal chemosensors for the detection of Hg2+ in aqueous solutions.

Novel poly(vinyl alcohols) (PVA) functionalized with pendant thermo- and pH-responsive groups were prepared by carbonyldiimidazole (CDI)-mediated couplings of N1,N1-diethylethane-1,2-diamine (DEEDA) with controllable modification degree. Nuclear magnetic response (NMR) and IR have verified the successful modification of PVA. The macro- and microscopic phase transition behavior of the obtained PVA-DEEDA-t (t = 10, 30, 70, and 90 h) was thoroughly characterized using various techniques, including turbidity measurement, NMR, and dynamic light scattering (DLS). PVA-DEEDA-t is demonstrated to possess tunable lower critical solution temperature (LCST) between 58 and 24 °C. LCST is dependent on solution pH and degree of PVA modification (14.1–20.9%). By combining DLS and DOSY characterizations, it can be concluded that both coil-to-globule transition and aggregation occurred to PVA-DEEDA-t during phase transition, while only coil-to-globule transition can be detected for the pristine PVA. 2D NOESY proved that the −NH– segment on PVA-DEEDA-t is in close (<5 Å) proximity to the main chain of PVA, as evidenced by the appearance of NOE signal between −NH– on DEEDA and −CH2–CH– chain of PVA when the temperature increased above LCST. To exploit the functional applications, the PVA-DEEDA-90 h was transformed into gel and film forms. PVA-DEEDA-90 h gel obtained by adding borax enabled controlled drug (e.g., RhB) release due to its temperature- and pH-dependent permeability. The PVA-DEEDA-90 h film was also casted on ITO glass, creating a smart surface with tunable wettability and interfacial ion transportation with high sensitivity toward the pH and temperature.

The differentiation of two nucleophilic amide groups in malonamides through a copper-catalyzed enantioselective intramolecular aryl C–N coupling reaction is demonstrated based on an asymmetric desymmetrization strategy. Such a method afforded enantioenriched 2-oxo-1,2,3,4-tetrahydroquinoline-3-carboxamides in high yields and moderate to good enantioselectivity.

Through a series of crystallographic snapshots of water chain-containing aquapores formed from numerous one-dimensionally aligned aquafoldamer molecules 2, we demonstrated here (1) a preferential recognition of the water molecules over methanol molecules by the assembled cavity-containing aquapores with a selectivity factor of at least 17.7, (2) the dynamic nature of the water chains and the aquapores in response to varying external stimuli that exert the most influential impact on the aromatic π–π stacking in the aquapores and (3) the aquapores undergo a significant rearrangement in order to accommodate water, rather than methanol, molecules.

•Four novel 2-arylethenyl-8-hydroxyquinoline Zn(II) complexes have been synthesized.•The aggregation behavior was investigated by 1H NMR, UV–vis and photoluminescence.•The photophysical properties can be tuned by introducing different substituents.A series of 2-arylethenyl-8-hydroxyquinoline ligands (A1–A4) with a trimethoxyphenyl, naphthyl, 2-fluoro-4-bromophenyl and anthracenyl group and their corresponding Zn(II) complexes (B1–B4) were synthesized and characterized by means of 1H NMR, ESI-MS, FT-IR and elemental analysis. A1 and A4 were characterized by single-crystal X-ray crystallography. The aggregation behavior of zinc salt and ligands in solution was investigated by several techniques, containing 1H NMR, UV–vis and photoluminescence (PL). The electronic nature and volume of arylethenyl substituents affect the absorption wavelength, the emission color, fluorescence lifetime, fluorescence quantum yield and thermostability of Zn(II) complexes. The experiments corroborated that the properties of Zinc(II) complexes can be tuned by introducing different functional substituents.Graphical abstract

One novel tetranuclear Cd(II) complex with formula [Cd4L6(NO3)2] (1) is accessible by solvothermal reaction of Cd(NO3)2 with a (E)-2-[2-(3-thienyl)ethenyl]-8-quinolinol ligand (HL), which was characterized by means of 1H NMR, ESI-MS, elemental analysis, IR and TGA. X-ray structural analysis indicated that 1 exhibited a double open cubane-like core structure, which was bridged by six 8-hydroxyquinolinate-based ligand. Rich aromatic stacking interactions and non-classical C–H···O weak interactions sustain the packing structure. The coordination behavior of cadmium salt and HL in solutions was performed by UV–vis and photoluminescence (PL). The experimental results corroborate that emission spectrum of the title complex in the solid state at room temperature gives strong yellow-green luminescence. In addition, the thermal stability, fluorescent lifetime, electronic calculation and quenching behaviors of C60 and EtBr-DNA interacted with the compound were also investigated.

Two 2-substituted 8-hydroxyquinoline ligands (HL1 and HL2) containing a cyano group were synthesized and characterized by ESI-MS, NMR spectroscopy and elemental analysis (EA). Solvothermal reactions of the two ligands with ZnX2 and CdX2 (X−: NO3− and OAc−) salts afforded three luminescent complexes, i.e., monomeric Zn(II) complex [Zn(L1)2] (1), trimeric Zn(II) complex [Zn3(L2)6] (2) and tetrameric Cd(II) complex [Cd4(L2)8] (3). These three complexes were characterized by single crystal X-ray diffractions, powder X-ray diffractions (PXRD), thermogravimetry analyses (TGA) and EA, illustrating a lamellar structure facilitated by noncovalent interactions such as aromatic π⋯π stacking and C–H⋯N H-bonds. Further investigations by UV–Vis, photoluminescence (PL) and fluorescence lifetime reveal tunable luminescence from yellow to red among 1–3 in the solid state.By self-assembly of the (E)-2-[2-(2-cyano)ethenyl]-8-hydroxyquinoline and (E)-2-[2-(4-cyano)ethenyl]-8-hydroxyquinoline ligand with zinc(II) and cadmium(II) metal ions, monomeric complex [Zn(L1)2] (1), trimeric complex [Zn3(L2)6] (2) and tetrameric complex [Cd4(L2)8] (3) have been obtained. The three complexes have been characterized by X-ray diffraction. Luminescence properties of complexes have been investigated.

Through a series of crystallographic snapshots of water chain-containing aquapores formed from numerous one-dimensionally aligned aquafoldamer molecules 2, we demonstrated here (1) a preferential recognition of the water molecules over methanol molecules by the assembled cavity-containing aquapores with a selectivity factor of at least 17.7, (2) the dynamic nature of the water chains and the aquapores in response to varying external stimuli that exert the most influential impact on the aromatic π–π stacking in the aquapores and (3) the aquapores undergo a significant rearrangement in order to accommodate water, rather than methanol, molecules.