A-Qing Wu

Eu3+-doped Tb3+ metal–organic frameworks emitting tunable three primary colors towards white light

A new bifunctional tetrazolate-5-carboxylate ligand has been prepared and employed in assembling 2-D Eu(III)–Zn(II) and Tb(III)–Zn(II) isostructural heterometallic MOFs with a (3,6)-connected kgd topology. The ligand in Tb3+ MOFs not only shows an antenna effect to transfer absorbed energy to Tb3+ centers to emit characteristic luminescence but also maintains good blue luminescent properties. Further, we have realized a rational design strategy to construct a series of Eu3+-doped Tb3+ MOFs emitting tunable three primary colors (RGB: red–green–blue) towards white light with high color rendering index and favorable correlated color temperature.

Hydrothermal syntheses, crystal structures and luminescent properties of zinc(II) coordination polymers constructed by bifunctional tetrazolate-5-carboxylate ligands

Two bifunctional 1H-tetrazolate-5-carboxylate ligands with different flexibilities, H2tza (1H-tetrazolate-5-acetic acid) and H2tzf (1H-tetrazolate-5-formic acid), were employed in the construction of zinc(II) complexes in the presence/absence of secondary ligands such as 2,2′-bipy and 4,4′-bipy. Three tza coordination polymers and two tzf dinuclear complexes, namely [Zn(tza)(H2O)]n (1), [Zn3(tza)2Cl2(2,2′-bipy)2(H2O)2]n (2), [Zn2(tza)2(4,4′-bipy)]n (3), [Zn(tzf)(H2O)3]2·2H2O (4) and [Zn(tzf)(2,2′-bipy)(H2O)]2·H2O (5), were hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Polymer 1 is a 3-D two-fold interpenetrating diamond-like network with tetranuclear [Zn(COO)]4 clusters as tertiary building units (TBUs) and µ3-κN3:κO2:κO1,N1 bridging tza as linkers. Polymer 2 presents a 2-D structure formed by the linkage of 1-D Zn-carboxylate [Zn(COO)]n helical chains and µ3-κN4:κO2:κO1,N1 bridging tza. In 3, 2-D (4,4) nets are built up with dinuclear [Zn(COO)]2 clusters and µ3-κN4:κO2:κO1,N1 bridging tza, which are pillared through 4,4′-bipy to gain a 3-D self-penetrating LB-1 (446108) topology. In dinuclear complexes 4 and 5, two Zn(II) atoms are bridged by a tzf ligand in a µ2-κN2:κO1,N1 fashion. The results denote that tetrazolate-5-carboxylate ligands can adopt variable coordination modes in the formation of the complexes, and different Zn-carboxylate aggregates can serve as tertiary building units (TBUs). The effects of the nature of tetrazolate-5-carboxylate ligands and secondary ligands, and hydrothermal reaction conditions on the structural topologies of the obtained complexes have been investigated. The photoluminescent properties and thermal stabilities of 1–5 have also been discussed.

Homochiral Zinc(II) Coordination Compounds Based on In-Situ-Generated Chiral Amino Acid–Tetrazole Ligands: Circular Dichroism, Excitation Light-Induced Tunable Photoluminescence, and Energetic Performance

We employed two pairs of new in-situ-generated chiral amino acid-tetrazole ligands in constructing homochiral Zn(II) coordination compounds: [Zn(tzet)]n (1a for (S)-tzet and 1b for (R)-tzet, H2tzet = N-[2-(1H-tetrazol-5-yl)ethyl]tryptophan) and [Zn(tzep)(H2O)2]·H2O (2a for (S)-tzep and 2b for (R)-tzep, H2tzep = N-[2-(1H-tetrazol-5-yl)ethyl]proline), which were hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. Structural analysis reveals that 1 features a 2D homochiral framework generated by both tetrazolate and carboxylate bridges in tzet(2-) ligands. The isolated structure of 2 is stabilized by extensive hydrogen bonds, which leads to formation of a supramolecular 2D architecture. The absolute configuration induced at the nitrogen atoms of 1 and 2 is strictly related to the neighboring chiral carbon atoms by hydrogen-bond interactions. To further investigate their chirality, the combined experimental and theoretical analyses of circular dichroism spectra reveal the absolute configurations and nature of the Cotton effects. Solid-state excitation and emission spectra for 1 and 2 at room temperature were investigated with relevant density of states calculation, and tunable photoluminescence emission of 1 under different excitation wavelengths was discussed. As nitrogen-rich tetrazolate compounds, 1 and 2 possess higher enthalpies of combustion and may serve as a new family of promising energetic materials.

Hydrothermal syntheses, crystal structures and physical properties of a new family of energetic coordination polymers with nitrogen-rich ligand N-[2-(1H-tetrazol-5-yl)ethyl]glycine

Hydrothermal reaction of N-(2-cyanoethyl)glycine and NaN3 with corresponding metal salts yielded three energetic coordination polymers: [Zn(tzeg)]n1 and [M(tzeg)(H2O)]n (M = Cd2+ for 2, Cu2+ for 3) (H2tzeg = N-[2-(1H-tetrazol-5-yl)ethyl]glycine), which were characterized by single-crystal X-ray diffraction. Nitrogen-rich tzeg2− ligand is a new in situ generated organic compound through [2 + 3] cycloaddition reaction of nitrile and azide, which adopts two different coordination modes in 1–3. Polymer 1 features an achiral 3D network built up by interweaving of left/right-handed helical channels. Isostructural 2 and 3 exhibit an achiral 2D network formed alternately by left/right-handed helical chains. As nitrogen-rich energetic materials, 1 and 3 possess higher enthalpies of combustion (ΔHc), which are −12.054 and −11.583 kJ g−1, respectively, than the classical energetic compounds 1,3,5-trinitro-1,3,5,-triazine (RDX, −9.6 kJ g−1) and 1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX, −9.44 to −9.88 kJ g−1). The solid-state excitation and emission spectra for 1–3 were investigated at room temperature, which reveals ligand-centered luminescent emissions in the intensity order of 2 > 1 > 3. Variable-temperature magnetic susceptibility data show that 3 displays a weak antiferromagnetic interaction mainly resulting from magnetic exchange coupling between Cu2+ ions through double tetrazolato bridges.

New Copper(II) and Nickel(II) Complexes with Bifunctional Tetrazolate-5-carboxylate Ligands: Syntheses, Crystal Structures, and Magnetic Properties

Four new complexes with bifunctional tetrazolate-5-carboxylate ligands of 1H-tetrazole-5-formic acid (H2tzf) and 1H-tetrazole-5-acetic acid (H2tza), namely two dinuclear [M(tzf)(H2O)3]2·2H2O (M = Cu 1, Ni 2) and two mononuclear [Cu(tzf)(2,2′-bipy)2]·5H2O 3 and Cu(tza)(2,2′-bipy)H2O 4, were prepared and structurally characterized by single-crystal X-ray diffraction. Two different coordination modes of tetrazolate-5-carboxylate ligands exist: a tridentate N,O-chelated-N-bridged mode in 1 and 2, and a bidentate N,O-chelated mode in 3 and 4, which was first observed for the tetrazolate-5-carboxylate complexes. Extensive hydrogen bonds play an important role in the construction of the supramolecular network. Variable-temperature magnetic susceptibility data show the presence of antiferromagnetic interactions in 1 and 2. The thermogravimetric analyses of complexes 1–4 are also discussed.

Zinc(II) coordination compounds based on in situ generated 3-(5H-tetrazol)benzaldehyde with diverse modes: hydrothermal syntheses, crystal structures and photoluminescent properties

Four Zn(II) tetrazolate coordination compounds have been hydrothermally synthesized and structurally determined by single-crystal X-ray diffraction. They are formulated as [Zn(3-tzbd)2]n·nH2O (1), [Zn2(3-tzbd)2(OH)2(4,4′-bipy)]n·nH2O (2), [Zn2(3-tzbd)3(N3)(4,4′-bipy)2]n·nH2O (3) and Zn2(3-tzbd)4(phen)2 (4), where 3-Htzbd = 3-(5H-tetrazol)benzaldehyde. The 3-tzbd− ligand, which was in situ generated through a [2 + 3] cycloaddition reaction of nitrile and azide, displays diverse coordination modes. Compound 1 exhibits a (4,4)-connected two-dimensional (2D) layer generated by the linkage of dinuclear units of [Zn2(μ2-3-tzbd)2] and μ2-3-tzbd− ligands. In 2, Zn(II) atoms are connected by μ2-3-tzbd− ligands and μ3-OH− anions to form unusual double-stranded stair-like chains, which are further linked by 4,4′-bipy to create a 2D sheet. Compound 3 features an unprecedented one-dimensional (1D) four-legged, triple-ladder chain composed of tetranuclear units [Zn4(μ2-3-tzbd)4(μ2-N3)2]. Two Zn(II) atoms in 4 are bridged by μ2-3-tzbd− ligands to result in an isolated dinuclear structure. In addition, the luminescent properties of 1–4 were investigated in the solid state at room temperature. The relevant density of states (DOS) calculation results show that their photoluminescence mainly originates from ligand-centered emission and is dependent on the organic ligand incorporated into the compounds.

Effect of nanoclusters induced by Si implantation on total dose radiation response of a SOI wafer

Si ion implantation with subsequent annealing was used to improve the irradiation hardness of SOI wafers. The reduced negative shifts in the threshold voltage of the n-channel transistors showed that the total dose radiation hardness was remarkably enhanced by this modification process, and the pseudo-MOS method was used to test the Id–VG characteristics of the SOI samples before and after irradiation. Photoluminescence (PL) spectra demonstrated that Si nanoclusters were formed during annealing in the buried oxide of the implanted samples, which were possibly the main candidates for charge compensation. X-ray photoelectron spectroscopy (XPS) results also suggested that reduction of the threshold voltage shifts was accompanied with the formation of Si nanoclusters near the peak of the implants. Furthermore, the effect of positive charge buildup can be partly reduced as a result of the improvement on proton trapping in the bulk of the oxide due to the implantation induced nanoclusters.

A Very Sensitive Pressure Sensor on a SOI-on-Cavity Substrate

A new structure combining a beam-diaphragm structure and a SOI-on-cavity substrate was proposed in this paper. Both high sensitivity and good linearity could be achieved due to the stress concentrated structure.

4-(1H-Tetra-zol-5-yl)benzoic acid monohydrate.

The asymmetric unit of the title compound, C8H6N4O2·H2O, consists of one 4-(1H-tetrazol-5-yl)benzoic acid molecule and one water molecule. Hydrogen-bonding and π–π stacking (centroid–centroid distance between tetrazole and benzene rings = 3.78 Å) interactions link the molecules into a three-dimensional network.

Zinc complexes of T-shaped trans-1,2,3-propenetricarboxylic acid with 1-D ribbon-like chain, 2-D rhombus-grid-like and herringbone-like layers, and non-interpenetrating 3-D open framework

Five zinc complexes of T-shaped trans-1,2,3-propenetricarboxylic acid (H(3)L) with 1-D ribbon-like chain, 2-D rhombus-grid-like and herringbone-like layers, and non-interpenetrating 3-D open framework have been obtained based on different building blocks. X-ray single crystal analyses show that the T-shaped information of H(3)L was nicely expressed in the construction of herringbone-like or ladder-like structure. All compounds were found to display blue fluorescent emissions.