Jian-Di Lin

A series of novel Pb(II) or Pb(II)/M(II) (M = Ca and Sr) hybrid inorganic–organic frameworks based on polycarboxylic acids with diverse Pb–O–M (M = Pb, Ca and Sr) inorganic connectivities

Solvothermal reactions of Pb(NO3)2 with aromatic polycarboxylic acids and the alkaline or alkaline earth metal nitrates led to six novel homo- or heterometallic lead(II)/carboxylate inorganic–organic hybrid materials, [Pb(p-BDC)(μ2-DMSO)] (1), [PbCa(m-BDC)2(μ1-DMSO)] (2), [PbCa(OH-m-BDC)2(CH3OH)2] (3), (Me2NH2)[PbSr(OH-m-BDC)(O-m-BDC)] (4), [Pb(SDBA)] (5), and [PbCa(SDBA)2(μ1-DMSO)2] (6) (p-H2BDC = 1,4-benzenedicarboxylate, m-H2BDC = 1,3-benzenedicarboxylate, OH-m-H2BDC = 5-hydroxy-1,3-benzenedicarboxylate, and H2SDBA = 4,4′-sulfonyldibenzoic acid). These hybrids have been fully characterized by single crystal X-ray diffraction, XRD, TGA, IR, UV-vis, elemental analysis and photoluminescence spectra. They are all three-dimensional structures except for 6, which displays a 2D layer structure. Topology analysis reveals that complexes 1–6 manifest dia, pcu, sne, hex, sev, and (4,4)-topological nets, respectively. Moreover, they exhibit diverse inorganic connectivities which have not been observed for the lead(II)/carboxylate systems, e.g. the 1D Pb–O–Pb chains in 1 and 5, the 2D Pb–O–Ca layer in 2, the 1D Pb–O–Sr chain in 4, and the 1D Pb–O–Ca chains in 3 and 6. The luminescent properties of these hybrid materials, the NLO property of 3 as well as the methane sorption property of 5 have also been investigated.

Hydrothermal syntheses, crystal structures and magnetic properties of four Mn(II) and Co(II) coordination polymers generated from new carboxylate-introduced 1,2,3-triazole ligands

A new carboxylate-introduced 1,2,3-triazole, 1-(3,5-dicarboxyphenyl)-4-carboxy-1H-1,2,3-triazole (H3dcpct), was synthesized by 1,3-dipolar cycloaddition of a terminal alkyne to azide in the presence of a Cu(II) salt. Hydrothermal reaction of H3dcpct and Mn(NO3)2·6H2O or Co(NO3)2·6H2O in different NaOH/H3dcpct molar ratios afforded four new coordination polymers [Mn(dcpt)(H2O)2]·0.25H2O 1, [Mn(dcpt)(H2O)] 2, [Co(dcpt)(H2O)2]·H2O 3 and [Co(H2O)6][Co2(dcpct)2(H2O)6]·2H2O 4 (H2dcpt = 1-(3,5-dicarboxyphenyl)-1H-1,2,3-triazole). The in situ hydrothermal decarboxylation of H3dcpct into H2dcpt in 1–3 was found and its possible mechanism is proposed. In 1 and 3, dcpt2− ligands bridge Mn(II) and Co(II) ions, respectively, to give two similar 2D layered structures with a (6,3)-connected network topology. Polymer 2 displays a whole achiral 3D open framework with both chiral and achiral channels in the same direction and possesses an unprecedented (3,6)-connected (4·82)(42·812·10) network topology. The structure of 4 features a 1D chained net, in which no decarboxylation occurred. Variable-temperature magnetic susceptibility data show that 1 exhibits a weak ferromagnetic interaction and 2 manifests an overall antiferromagnetic interaction between their respective Mn(II) ions, while 3 and 4 display an antiferromagnetic interaction between Co(II) ions and/or spin-orbital coupling. The thermal stabilities of all obtained polymers have also been examined.

Tetraalkylammonium cations as templates in the construction of two cadmium(II) metal–organic frameworks

Hydrothermal reaction of cadmium salts with HATZ in the presence of R4NBr (R = Et, Pr) led to two organic cation templated Cd(II) MOFs, (Et4N)[Cd6Br5(ATZ)8]·H2O (1) and (Pr4N)[Cd4Br5(ATZ)4] (2) (HATZ = 5-amino-tetrazolate, Et = ethyl and Pr = propyl), which are the first examples of tetraalkylammonium cations templated N-heterocyclic ligand based MOFs. These two MOFs have been fully characterized by single crystal X-ray diffraction, XRD, TGA, IR, elemental analysis, photoluminescence spectra and combustion heat measurement. The anionic frameworks of 1 and 2 are three- and two-dimensional, respectively. Topological analyses show that compound 1 exhibits an unprecedented binodal (4,10)-connected network, which is a subnet of the (12,12)-connected tcj net, and compound 2 is a 2-D uninodal four-connected network when the Cd6 clusters in these two MOFs are viewed as nodes. Moreover, compound 1 maybe have potential application as an energetic material due to its high enthalpy of formation.

Synthesis, structures and luminescent properties of new Pb(II)/M(I) (M = K, Rb and Cs) frameworks based on dicarboxylic acids: a novel icosahedral Pb6-M6 SBU

Reactions of Pb(CH3COO)2·3H2O, MNO3 (M = K, Rb, and Cs) with m-H2BDC (1,3-H2BDC = 1,3-benzenedicarboxylic acid) in a mixed-solvent of DMF and methanol (v/v = 2/1) resulted in the formation of novel metal–organic frameworks [(Me)4N]2[Pb6M6(m-BDC)9(OH)2]·H2O (1: M = K; 2: M = Rb; 3: M = Cs). With H2SDBA (H2SDBA = 4,4′-sulfonyldibenzoic acid), two new lead(II) coordination polymers, [K2Pb(SDBA)2(μ3–H2O)]·3H2O (4) and [Cs2Pb2(SDBA)3(DMF)] DMF (5), were isolated. These complexes have been fully characterized by elemental analysis, PXRD, FTIR, TGA and single crystal X-ray diffraction. Compounds 1–3 are 3-D coordination frameworks built by a novel 12-metal heterometallic Pb6-M6 cage that extends topologically into an eight-connected hex network viaisophthalic acid ligands. Compounds 4 and 5 are new 3-D lead(II) MOFs constructed by ladder-like Pb(II)/K(I)/SDBA2− and rod-shaped Pb(II)/Cs(I)/SDBA2− motifs, respectively. The Pb(II) ions in these complexes show different coordination geometries with various coordination numbers (5, 7 and 9). In addition, an ideal T-shaped μ3-H2O is observed in 4. The SDBA2− ligands in 4 and 5 display three types of new coordination modes that have not been observed before. At room temperature, 1–3 exhibit strong emissions in the solid-state which can be attributed to ligand-to-metal charge transfer between the delocalized π bonds of carboxylate groups and p orbitals of lead(II) centers.

Electrochemical investigation and determination of procaterol hydrochloride on poly(glutamic acid)/carboxyl functionalized multiwalled carbon nanotubes/polyvinyl alcohol modified glassy carbon electrode

Poly(glutamic acid) (P-GLU)/carboxyl functionalized multiwalled carbon nanotubes (MWCNTs-COOH)/polyvinyl alcohol (PVA) modified glassy carbon electrode (GCE) has been successfully prepared and the electrochemical behavior of procaterol hydrochloride (ProH) was studied. The results show that the as-prepared modified electrode exhibits a good electrocatalytic property towards the oxidation of ProH in 0.2M phosphate buffer solution (PBS) (pH 6.0) due to the enhanced oxidation peak current at ~+0.59V. Under optimal reaction conditions, the oxidation peak current of ProH is proportional to its concentration in the linear dynamic ranges of 0.060 - 8.0μM (R = 0.9974), with a detection limit of 8.0 × 10-9M. Finally, this method was efficiently used for the determination of ProH in tablets and human urine with recoveries of 88.5~98.7% and 89.2 ~ 108.0%, respectively.

Highly sensitive determination of lead( ii ) and cadmium( ii ) by a large surface area mesoporous alumina modified carbon paste electrode

Nanosized mesoporous γ-alumina (M-γ-Al2O3) was first prepared and then modified into a carbon paste to fabricate a novel modified carbon paste electrode. The prepared alumina has pores with an amorphous wall and large surface area. The electrochemical behavior of the modified carbon paste electrode was investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The modified carbon paste electrode was employed to determine Pb2+ and Cd2+ simultaneously by a differential pulse voltammetry (DPV) method. Amperometric determination was carried out in 0.1 mol L−1 NaAc–HAc buffer solution (pH 6.0) after enriching for 360 s at −1.0 V. The oxidation peak currents of Pb2+ and Cd2+ were proportional to their concentration in the range of 0.001–10 μmol L−1 and 0.01–10 μmol L−1, respectively. The detection limits of Pb2+ and Cd2+ were 0.20 nmol L−1 and 2.0 nmol L−1 (S/N = 3), respectively. The modified carbon paste electrode shows good stability, repeatability and sensitivity. The proposed method was applied to the determination of Pb2+ and Cd2+ in water samples with satisfactory results.

A hydrogen peroxide biosensor based on horseradish peroxidase/poly(L-leucine)/polydopamine modified glassy carbon electrode

A simple and practical sensor of hydrogen peroxide (H2O2) was designed successfully. The mixture of horseradish peroxidase (HRP) and chitosan (Chit) are effectively immobilized on the surface of poly-L-leucine/polydopamine modified glassy carbon electrode (PL-LEU/PDA/GCE). Under the optimum conditions, the biosensor based on HRP exhibits a fast amperometric response (within 3 s) to H2O2. The linear response range of the sensor is 0.5–952.0 μmol L–1, with the detection limit of 0.1 μmol L–1 (S/N = 3) and the sensitivity of 0.23 A L moL–1 cm–2. The apparent Michaelis–Menten constant (kMapp) of the biosensor is evaluated to be 0.12 mmol L–1, which suggests that the HRP-Chit/PL-LEU/PDA/GCE shows a higher affinity for H2O2. The sensor exhibits good sensitivity, selectivity, stability and reproducibility. The proposed method has been successfully applied to the determination of H2O2 in practical samples.

Crystal structure, optical properties, and theory study of a 1-D bromoplumbate stabilized by in situ generated N-alkylated DABCO cation

Abstract We report the exploration of the stabilization effect of the in situ generated N-alkylated DABCO (DABCO = 1,4-diazabicyclo[2.2.2]octane) cation in the family of bromoplumbates and a 1-D bromoplumbate, (Et2DABCO)2n(Pb3Br10)n (1), has been prepared by solvothermal conditions. Optical diffuse reflectance determination shows the band gap of 1 is 3.69 eV, which manifests that 1 is a wide band gap semiconductor. Compared with the band gap of bulk PbBr2 (3.84 eV), 1 exhibits 0.15 eV red shift of absorption edge. While for the reported iodo analogs of this compound, (MPDA)2n(Pb3I10)n and (Et2DABCO)2n(Pb3I10)n, they exhibit 0.53 and 0.47 eV blue shift of the energy gaps compared with the measured value of 2.30 eV for bulk PbI2, respectively. The photoluminescent study of 1 shows that it exhibits a broad emission band centered at 697 nm upon photoexcitation by 345 nm (amount to 3.59 eV). The calculated density of states manifests the theoretical value of the band gap of 1 is 3.422 eV and the origination of photoluminescence can be ascribed to the transition of bonding electrons of Br– anion to the empty orbits of Pb(II) ion.