Yan-Xuan Qiu

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.

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.

The syntheses, structures and azo–hydrazone tautomeric studies of three triazole/tetrazole azo dyes

Three heterocyclic azo dyes of azotriazolyl-2,7-dihydroxynaphthalene (H3AD), azotetrazolyl-2-naphthol (H2ATN) and azotetrazolyl-2,7-dihydroxynaphthalene (H3ATD) have been synthesized and characterized by IR, Raman spectra, 1H, 13C NMR and X-ray single-crystal diffraction techniques and their azo–hydrazone tautomerism has been achieved by pH control and coordination-coupled proton transfer. UV-vis spectra have been used to monitor the pH-titration and metal-ion complex experiments for three solutions of H3AD, H2ATN and H3ATD and the analysis of their spectral data has provided a clear proof that the hydrazone form is the dominant tautomer in acidic and neutral solutions, while the azo form is the dominant one in alkaline solutions. Crystallographic data demonstrate that the neutral dyes exist as hydrazone tautomers but are changed to azo tautomers when they coordinate to metal ions. The time-dependent density functional theory (TD-DFT) calculations are used to demonstrate the UV-vis spectroscopic properties.

Two 5-tetrazolylazo-8-hydroxyquinoline-based Zn(II) and Mn(II) complexes: syntheses, structures and optical properties

Two 5-tetrazolylazo-8-hydroxyquinoline (TTHQ) Zn2+ and Mn2+ complexes, [Zn(TTHQ)(en)]·2H2O (en = ethylenediamine) (1) and [Mn2(TTHQ)2(H2O)6]·2H2O (2), were synthesized and characterized by single-crystal X-ray diffraction analysis. Stacking (π–π) and hydrogen-bonding interactions are responsible for the stabilization of the supramolecular structures. UV–vis spectral changes and photoluminescent properties of TTHQ, 1 and 2 were investigated and a red emission was found. The hydrogen-bonding interaction energies in 1 and 2 were calculated using density functional theory at the WB97XD/6-31++G level. Graphical abstract

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.

In-situ nano-crystal-to-crystal transformation synthesis of energetic materials based on three 5,5′-azotetrazolate Cr(III) salts

The in-situ nano-crystal-to-crystal transformation (SCCT) synthesis provides a powerful approach for tailoring controllable feature shapes and sizes of nano crystals. In this work, three nitrogen-rich energetic nano-crystals based on 5,5′-azotetrazolate(AZT2−) Cr(III) salts were synthesized by means of SCCT methodology. SEM and TEM analyses show that the energetic nano-crystals feature a composition- and structure-dependent together with size-dependent thermal stability. Moreover, nano-scale decomposition products can be obtained above 500 °C, providing a new method for preparing metallic oxide nano materials.

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, electrochemical and optical properties of four transition metal complexes based on the 1-triazolyl-3-benzimidazolyltriazene ligand

Four transition metal complexes based on the 1-triazolyl-3-benzimidazolyltriazene (H3TBIT) ligand of [Co(H2TBIT)(HTBIT)] (1), {[Cu(H2TBIT)(SCN)]·H2O} (2), [Cd2(H3TBIT)2(H2O)2Cl4] (3) and {[Ni3(H2TBIT)2(HTBIT)2(en)2]·IPA·2H2O} (en = ethylenediamine, IPA = isopropanol) (4) have been synthesized and characterized by single crystal X-ray diffraction analysis. In 1–4, the triazene ligand acts in different coordinating or bridging modes resulting in two mononuclear structures for 1 and 2, one dinuclear structure for 3 and one trinuclear structure for 4. Different structural 1–4 are further self-assembled through hydrogen bonds or π–π, C–H⋯π or metal–π interactions to form 3D supramolecular structures. The electrochemical properties in aqueous solutions as well as the photoluminescent properties in ethanol of H3TBIT and 1–4 are investigated. The TD-DFT calculations at the B3LYP/6-311++G(d,p) level for H3TBIT has been used to demonstrate the characteristic absorption spectrum.

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.

Hydrothermal Synthesis and Crystal Structure of Sm~(3+) Complex with Mononuclear Structure Based Bis(tetrazoly)amine Ligand

A new Sm3+complex [Sm2(BTA)3.(H2O)10].5H2O(1)(H2BTA=5,5-bis(1H-tetrazoly)amine,CAS No.127661-01-2) was synthesized by the hydrothermal reaction of SmCl3.6H2O and bis(tetrazoly)amine,and characterized by X-ray diffraction and elemental analysis.The crystal of 1 is triclinic with space group P1.In 1,two Sm3 + ions are coordinated to the chelated N atoms of BTA anions and water molecules to give two different mononuclear units with a distorted tetragonal antiprism structure.A 3D supermolecular structure is formed by three different intermolecular hydrogen bonding interactions of O-H…N,O-H…O and N-H … N in this complex.CCDC: 894688