Isothiocyanates as derivatization reagents for amines in liquid chromatography/electrospray ionization–tandem mass spectrometry

The applicability of 3‐pyridyl isothiocyanate, p‐(dimethylamino)phenyl isothiocyanate and m‐nitrophenyl isothiocyanate as the derivatization reagents for amines in high‐performance liquid chromatography/electrospray ionization–tandem mass spectrometry (LC/ESI‐MS/MS) was examined. The generated derivatives of amines with these reagents were favorably separated on the reversed‐phase column and detected by ESI‐MS/MS. The C–N bond of the generated thiourea structure was efficiently cleaved by collision‐induced dissociation and gave the single and intense product ion. Among the three reagents, 3‐pyridyl isothiocyanate was the most suitable as the derivatization reagent with regard to the reactivity to amines and the detection sensitivity. Copyright © 2009 John Wiley & Sons, Ltd.     

Vinyl polymerization of norbornene catalyzed by 2‐Py‐amidine Ni(II) complex/methylaluminoxane systems

Two 2‐Py‐amidine ligands (2‐Py―NH―C(Ph)═N―Ar, Ar = 2,6‐Me₂C₆H₃ and 2,6‐ⁱPr₂C₆H₃) and the corresponding Ni(II) complexes ( 1 and 2 ) were synthesized and characterized using elemental analysis and FT‐IR, UV–visible, ¹H NMR and ¹³C NMR spectroscopies. X‐ray crystal structures indicate that the chelate ring conformation of the less bulky complex 1 is relatively planar compared with that of the bulky complex 2 . Paramagnetic ¹H NMR and ¹³C NMR studies show that, in solution, the time‐average structures of complexes 1 and 2 have mirror symmetry. Both complexes 1 and 2 were used as catalyst precursors for norbornene polymerization with methylaluminoxane as a co‐catalyst. The effects of Al/Ni ratio, temperature and structure of precursors on the catalytic performance were investigated. Copyright © 2014 John Wiley & Sons, Ltd.     

A Dynamic Crystal‐to‐Amorphous Transformation Microporous ZnII Mixed Neutral‐ligand Metal‐organic Polymer {[Zn(bpp)2(μ‐4,4′‐bipy)(H2O)2](ClO4)2·H2O}n

A new rarely reported Zn^II mixed‐polypyridine coordination polymer with both rigid and flexible spacers, {[Zn(bpp)₂(μ‐4,4′‐bipy)(H₂O)₂](ClO₄)₂ · H₂O}_n ( 1 ), has been synthesized and characterized by elemental analysis, IR‐, ¹H NMR‐, ¹³C NMR spectroscopy and single‐crystal X‐ray diffraction. The thermal stability of compound 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The single‐crystal X‐ray structure of 1 shows that the complex has been formed from a 1D polymer as a result of bridging by the 4,4′‐bipy ligands. Solution and solid‐state luminescent spectra of the compound 1 indicate intense fluorescent emissions at ca. 353.6 and 468.8 nm, respectively. Removal of the interstitial water guest molecules results in a loss of crystallinity, but exposure to water vapor reestablishes the original structure, thus constituting 1 as a third‐generation porous framework.     

Synthesis and biological evaluation of <Superscript>99m</Superscript>Tc-HEDTA/HYNIC-MPP4 complex for 5-HT<Subscript>1A</Subscript> receptor imaging

5-HT_1A receptor is associated with a variety of pathophysiology of neuropsychiatric disorders. Accordingly, we have synthesized a new 5-HT_1A receptor ligand (HYNIC-MPP4) and labeled it with ^99mTc using N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) as coligand. ^99mTc-HEDTA/HYNIC-MPP4 was prepared under pH 6 at room temperature. Biodistribution of 99mTc-HEDTA/HYNIC-MPP4 in normal mice showed that this complex had moderate brain uptake (0.60% ID·g⁻¹ at 2 min p.i.) and good retention. The hippocampus had the highest radioactivity uptake at 2 min p.i. (1.84% ID⋆g⁻¹). The ratio of Hipp/CB was 3.1 at 2 min p.i. and increased to 4.4 at 60 min p.i. After blocking with 8-hydroxy-2-(dipropylamino) tetralin, the uptake of hippocampus was decreased significantly from 1.84% ID·g⁻¹ to 0.53% ID·g⁻¹ at 2 min p.i., while the cerebellum had no significant decrease. This ^99mTc complex could be a potent agent for 5-HT_1A receptor imaging. Supported by the National Natural Science Foundation of China (Grant No. 20401004) and the Analysis and Test fund of Beijing Normal University     

Hydrothermal synthesis and structure of a 2D supramolecular framework with right‐ and left‐helices based on mixed ligands

An exploration of the cobalt‐OH‐BDC‐bpp system under hydrothermal conditions, has led to the isolation of a novel framework [Co(OH‐BDC)(bpp)_0.5(H₂O)]_n (OH‐BDC = 5‐hydroxyisophthalic acid, bpp = 1,3‐bi(4‐pyridyl)propane). Single‐crystal X‐ray analysis reveals that it crystallizes in the monoclinic space group P2₁/n. a = 10.235(8) Å, b =17.882(14) Å, c = 14.291(11) Å, β = 92.107(9)°.The cobalt ions are linked into an extended helical chain via OH‐BDC and mono‐coordinated bpp ligands through hydrogen‐bonding interactions. Further these helical chains are united together through the bridging bpp to form a 2D layer and the adjacent chains possess the opposite chirality. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Pseudohalide‐directed Assembly of Two Zinc(II) Coordination Polymers with a 3,4‐Bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole Tecton

The zinc(II) pseudohalide complexes {[Zn(L³³⁴)(SCN)₂(H₂O)](H₂O)₂}_n ( 1 ) and [Zn(L³³⁴)(dca)₂]_n ( 2 ) were synthesized and characterized using the ligand 3,4‐bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole (L³³⁴) and ZnCl₂ in presence of thiocyanate (SCN^–) and dicynamide [dca, N(CN)₂^–] respectively. Single‐crystal X‐ray structural analysis revealed that the central Zn^II atoms in both complexes have similar octahedral arrangement. Compound 1 has a 2D sheet structure bridged by bidentate L³³⁴ and double μ_N,S‐thiocyanate anions, whereas complex 2 , incorporating with two monodentate dicynamide anions, displays a two‐dimensional coordination framework bridged by tetradentate L³³⁴ ligand. Structural analysis demonstrated that the influence of pseudohalide anions plays an important role in determining the resultant structure. Both complexes were characterized by IR spectroscopy, microanalysis, and powder X‐ray diffraction techniques. In addition, the solid fluorescence and thermal stability properties of both complexes were investigated.     

相转移催化合成吡啶三唑并噻二唑及舒张血管活性研究

3-(3-吡啶基)4氨基-5-巯基-1，2，4-均三唑(1)与羧酸在相转移催化剂四丁基碘化铵和三氯氧磷催化作用下，高收率制得3-(3-吡啶基)-6-取代-s-1，2，4-三唑并[3，4-b]噻二唑(2a-2s)．体外舒血管活性试验表明，大部分化合物具有较好的舒张生理活性．     

One‐Dimensional Holodirected Lead(II) Coordination Polymer, [Pb(μ2‐TPPZ)(NO3)(ClO4)]n (TPPZ = 2, 3, 5, 6–tetra(2‐pyridyl)pyrazine)

A lead(II) complex with 2,3,5,6‐tetra(2‐pyridyl)pyrazine (TPPZ), nitrate, and perchlorate ligands has been synthesized and characterized by CHN elemental analysis and IR and ²⁰⁷Pb NMR spectroscopy. The single crystal X‐ray data of the [Pb₂(μ‐TPPZ)₂(NO₃)₂(ClO₄)₂] compound show that the complex is a one‐dimensional coordination polymer and that the Lead atom has a less‐common, ten‐coordinate holodirected geometry.     

Synthesis,Crystal Structure and Magnetic Properties of [Fe(bpe)4(H2O)2](TCNQ)2 (bpe = trans‐1,2‐bis(4‐pyridyl)ethane and TCNQ = tetracyanoquinodimethane)

The synthesis, structure and magnetic properties of [Fe(bpe)₄(H₂O)₂](TCNQ)₂ ( 1 ) are reported. 1 crystallizes in the triclinic P space group, a = 13.481(5), b = 14.887(3), c = 16.663(4) Å, α = 101.048(18), β = 112.84(2), γ = 90.92(2)°, V = 3009.6(14) ų, Z = 2. The iron atom defines a compressed octahedron with the equatorial positions occupied by the bpe molecules which act as monodentate ligands and the two axial positions occupied by water molecules. The TCNQ^? radical counterions are uncoordinated and interact by pairs defining (TCNQ)₂^2? units strongly coupled antiferromagnetically. The iron(II) atoms are in the high spin state and its magnetic behaviour indicates the occurrence of zero‐field splitting of the S = 2 ground state.