Wen-Bin Chen

Unusual π−–π− stacking interactions between 5,5′-azotetrazolate(AT) anions in six AT based 3d metal photochromic complexes

Six 5,5′-azotetrazolate based supramolecular complexes of {[Co(en)3]2(AT)3·3H2O} (1), {[M(en)2(trans-AT)2](trans-H2en)·2H2O} (M = Ni, 2; Cu, 3), {[Ni(en)2(trans-AT)](trans-AT)(trans-H2en)·2H2O} (4), {[Cu(en)2(trans-AT)]·2H2O} (5) and {[Cu(en)2(trans-AT)0.5](trans-AT)0.5} (6) (en = ethylenediamine) have been synthesized and characterized by single crystal X-ray diffraction analysis. The trans-AT2− anions in 1–6 show four different coordinating modes. In 1–6, the unusual face-to-face AT2−–AT2− π−–π− stacking interactions with the separated interplanar center to center distances ranging from 3.32 to 4.0 A were observed. The π−–π− stacking, hydrogen bonding and electrostatic interactions are responsible for the stabilization of these 3D supramolecular structures. The aqueous solutions of 1–6 with the concentration of 2 × 10−5 mol L−1 show photochromism that originates from the trans–cis isomerisation of AT2− anionic ligands. The onion cell imaging with 1–6 as labels has also been reported.

Syntheses, supramolecular structures, magnetic and photochromic properties of six lanthanide complexes based on the 5-azotetrazolyl salicylic acid ligand

Six lanthanide complexes based on the 5-azotetrazolyl salicylic acid (H3ASA) ligand of {[Er(H2ASA)(HASA)(H2O)6]·6H2O} (1), {[Ln(H2ASA)(HASA)(H2O)4]2·6H2O} [Ln = Er (2), Ho (3)], [Ln(H2ASA)(HASA)(H2O)4] [Ln = Nd (4), Gd (5)] and {[Dy(ASA)(H2O)5]·5H2O} (6) have been synthesized and characterized by single crystal X-ray diffraction analysis. In 1–6, the carboxyl group acts in different coordinating or bridging modes resulting in a mononuclear structure for 1, two dinuclear structures for 2 and 3 and three one-dimensional structures for 4–6, and the unusual π−–π stacking between tetrazolate anions and phenyl rings and various hydrogen bonding interactions are observed. The energies for π−–π stacking interactions were calculated and demonstrated at the MP2 level using the Gaussion 09 suite. The magnetic properties of 2–6 and photochromism for aqueous solutions of 1–6 were investigated.

Three 5,5′-azotetrazolate-based cadmium(II) and zinc(II) complexes: syntheses, structures and photochromic and cell imaging properties

Three 5,5′-azotetrazolate(AT)-based complexes, [Cd(pn)2(trans-AT)] (pn = 1,3-diaminopropane) (1), [Cd(en)2(trans-AT)]·4H2O (en = ethylenediamine) (2), and {[Zn(en)2(trans-AT)0.5](trans-AT)0.5} (3), have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complexes 1–3 show three different supramolecular structures, in which the trans-AT2− have three different bridging modes. Complex 1 shows a 1-D zigzag chain structure formed by each μ 2-trans-AT2− bridging two Cd2+ ions. In 2, the trans-AT2− anions are μ 2 bridging, linking Cd2+ ions to give another 1-D zigzag chain, which forms a 2-D supramolecular network by intermolecular hydrogen bonds. In 3, [Zn(en)2(trans-AT)0.5]+ forms a 2-D network structure with each μ 4 bridging trans-AT2− linking four different Zn2+ ions. The [Zn(en)2(trans-AT)0.5]+ and uncoordinated trans-AT2− are further connected through face-to-face π–π stacking and electrostatic interactions, rendering a 3-D supramolecular network. The photochromism of aqueous solutions of 1–3 and [Na2(trans-AT)(H2O)5] (L) and the photoluminescence in solid samples of 2 and 3 as well as onion cell imaging with 2–3 and L as labels have been studied and reported.

Structures of six photochromic 3d complexes containing 3,3′-azobis-1,2,4-triazole ligand

Six 3,3′-azobis-1,2,4-triazole (H2ABT) complexes [Mn2 (ABT)(bpy)4(H2O)2]·(ABT)·4H2O (1), [Mn(ABT)(H2O)4]·H2O (2), [Co(ABT)(en)2]·(H2ABT)·2H2O (3), [Cd(ABT)0.5(en)2]·(ABT)0.5·2H2O (4), [Zn(ABT)0.5(en)2]·(ABT)0.5·2H2O (5), [Cu(ABT)0.5(en)2]·(ABT)0.5 (6), where en = ethylenediamine, bpy = 2,2-bipyridine, have been synthesized and characterized by single crystal X-ray diffraction analysis. In complexes 1–6, the unusual face-to-face π–π stacking interactions among heterocyclic aromatic rings and three kinds of hydrogen bonds C–H⋯O, N–H⋯O and O–H⋯O are observed. The π–π stacking, hydrogen bonding and electrostatic interactions are responsible for the stabilization of these 2D and 3D supramolecular structures. The aqueous solutions of 1–6 with the concentration of 6 × 10−5 mol dm−3 show photochromism. The fluorescent properties of solid-state samples of 1–6 have been investigated. The π–π stacking interaction energies for 1–6 were calculated at MP2 level using Gaussian 09 suite and demonstrated.

Synthesis, structure, photochromic, and fluorescent imaging properties of sodium-3,3′-azobis(1,2,4-triazole)

A crystal of [Na2(ABT) · 5H2O] (ABT = 3,3′-azobis(1,2,4-triazole)) (1) was characterized by single-crystal X-ray diffraction. Complex 1 features a 1-D chain and each ABT2− is a µ1,2,6 bridge with three triazole nitrogen atoms coordinating to three different sodium(I). Aqueous solution of 1 (6.0 × 10−5 mol L−1) shows photochromism. Fluorescence of solid 1 displays green photoluminescence under UV-light or laser irradiation and can be employed to label onion cell.

M2+ and Ln3+-catalyzed synthesis of a [1,2,4]triazine core via intramolecular C–H/N–H functionalization and C–N bond formation (M = Mn, Zn, Cd; Ln = Dy, Tb)

A novel approach for the direct synthesis of a 1,2,4-triazine core starting from eight azo conjugated aromatic compounds, 5-azo-(1,2,4-triazolyl) salicylic acid, 5-azo-(3-methyl-1,2,4-triazolyl) salicylic acid, 5-azo-(3-carboxyl-1,2,4-triazolyl) salicylic acid, 5-azo-(1,2-pyrazolyl) salicylic acid, 4-azo-(1,2,4-triazolyl) phenol, 4-azo-(3-carboxyl-1,2,4-triazolyl) phenol, 4-azo-(1,2-pyrazolyl) phenol, and 5-azo-(1,2,4-triazolyl) acetylsalicylic acid, via transition or lanthanide metal catalyzed intramolecular C–H/N–H functionalization and C–N bond formation has been developed under one-step hydrothermal synthetic conditions.

Syntheses, structures and photochromic properties of two tetrazolylazo-based K+ and Cd2+ complexes

A 5,5′-azotetrazole (H2AT)-based K+ complex of [K3(AT)1.5(H2O)4] (1) and another 5-azotetrazolyl salicylic acid (H3ASA)-based Cd2+ complex [Cd(H2ASA)2(H2O)2] (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complex 1 shows a 3-D structure formed by two μ7- and μ8-bridging trans-AT2− ligands and μ2-bridging waters linking three kinds of K+ ions. Complex 2 features a 1-D chain structure in which each trans-enol H2ASA− anion is a μ2-bridging ligand with one N(tetrazole) atom and one O(carboxyl) coordinating to two different Cd2+ ions. The photochromic and photoluminescent properties for aqueous solutions of 1 and 2 were investigated. Graphical Abstract A 5,5′-azotetrazole (H2AT) based K+ complex, [K3(AT)1.5(H2O)4], (1) and a 5-azotetrazolyl salicylic acid (H3ASA) based Cd2+ complex, [Cd(H2ASA)2(H2O)2] (2), are reported.

Photoluminescence and labelling for microcrack bone of N-salicylidene-3-amino-1,2,4-triazole.

A new Schiff base of N-salicylidene-3-amino-1,2,4-triazole (SAT) was synthesized and its photoluminescent, photochromic and thermochromic properties were characterized and demonstrated. The fluorescence lifetime and quantum yield of SAT were measured and the microcrack bone imaging using SAT as a fluorescent label was observed by laser scanning confocal microscope (LSCM). The absorption spectrum of SAT was demonstrated using DFT/TD-DFT calculation.

Crystal Structures, UV Spectra of Solid Iodide Anionic Water Clusters I–(H2O)1–4, and Electrochemical Reaction of I–(H2O)1–4 → I· + e–(H2O)1–4

Four iodide anionic water clusters of I(-)(H2O)1-4 in two supramolecular complexes of [Fe(phen)3][I2(H2O)3] (1) and [Zn(phen)3][I2(H2O)4.5] (2) have been determined by single-crystal X-ray diffraction analysis. The diffuse reflectance spectra for the solid iodide anionic water clusters of I(-)(H2O)1-4 were investigated, and their absorption bands were demonstrated by denisty functional theory calculation. The electrochemical reaction of I(-)(H2O)1-4 → I· + e(-)(H2O)1-4 with the oxidation potential of Ep = 0.61 eV was first found and reported in two aqueous solutions (1 mmol·dm(-3)) of 1 and 2.