Cluster. -The new intrinsic yellow phosphor (II) crystallizes in the monoclinic space group C2/m with Z = 4 (single crystal XRD). The structure contains octahedral Ga6(OH)4O26 hexamers which are interlinked to microporous octahedra-oxalate hybrid sheets. Each hexamer is also connected to 6 GaO4 and 10 PO4 tetrahedra to form 22-polyheral secondary building units, which are further connected to a three-dimensional hybrid framework with nm-sized channels. Under excitation over the broad range 360-500 nm (II) emits yellow (540 nm) luminescence with a photoluminescence quantum efficiency of up to 42%.

Research into the synthesis of nanoporous materials developed from zeolites, [1] aluminosilicates, [2] open-framework metal phosphates, [3][4] coordination polymers, [5] and metalorganic frameworks (MOFs) [6][7][8] has progressed faster than ever in the last twenty years. MOFs, the most recently established of these materials, have received most attention because of their high hydrogen storage capacity and therefore their potential for use in high-performance fuel cells. [9][10] While major attention has been focused on pore-size-related absorption properties, we have concurrently discovered extraordinary photoluminescence (PL) properties in openframework metal phosphates. [11][12][13][14][15][16] We discovered two metal phosphates, NTHU-4 [12] and NTHU-6, [13] which have novel nanoporous structures. These metal phosphates, unlike commercialized or developed color-conversion phosphors with emissions that originate from emitting activators doped into condensed host lattices, [17] contained no metal activators or any form of chromophores, but could emit intense yellow light under the excitation of near-ultraviolet (NUV) and blue light. A yellow-light phosphor integrated with a blue light-emitting diode (LED) to produce white light is the current mainstream of display technology, [18] although existing yellow phosphors that can be efficiently excited by NUV or blue light are very limited in number and range. A larger variety of advanced materials to add to the yellow phosphor YAG:Ce (YAG = yttrium aluminum garnet) is therefore in great demand. The intriguing optical properties of NTHU-4 and NTHU-6 has led us to explore a new class of color-conversion phosphors based on nanoporous host structures that have an intrinsic emission mechanism beyond our current understanding. [19] Existing inorganic yellow-light phosphors are all extrinsic illuminants. Before the two nanoporous structures were reported by us, no inorganic phosphate host that could emit yellow light but was not doped with lanthanide ions had been reported. The extraordinary intrinsic yellow emission was proposed to closely correlate with defects that result from the disorder in the large pores of the structure, firstly observed in NTHU-4 and later in NTHU-6. In the latter study, we had also speculated that the molecule 4,4'-trimethylenedipyridine (tmdp), the common template of both structures, acted as a sensitizer. To affirm and enhance the new phosphor system and rationalize an emission mechanism for the activator-free PL, it was imperative to produce further examples of these structures. In the pursuit of advanced and economical synthetic procedures for making new functional materials, we focused on the environmentally friendly deep eutectic solvent (DES). [20][21][22][23] Herein, we report the first nanosized channel structure successfully synthesized in a DES and also the first organically templated gallium oxalatophosphite compound, NTHU-7. It adopts an unprecedented organicinorganic hybrid nanotubular structure (Figure 1), which exhibits an even mor...

Research into the synthesis of nanoporous materials developed from zeolites, [1] aluminosilicates, [2] open-framework metal phosphates, [3][4] coordination polymers, [5] and metalorganic frameworks (MOFs) [6][7][8] has progressed faster than ever in the last twenty years. MOFs, the most recently established of these materials, have received most attention because of their high hydrogen storage capacity and therefore their potential for use in high-performance fuel cells. [9][10] While major attention has been focused on pore-size-related absorption properties, we have concurrently discovered extraordinary photoluminescence (PL) properties in openframework metal phosphates. [11][12][13][14][15][16] We discovered two metal phosphates, NTHU-4 [12] and NTHU-6, [13] which have novel nanoporous structures. These metal phosphates, unlike commercialized or developed color-conversion phosphors with emissions that originate from emitting activators doped into condensed host lattices, [17] contained no metal activators or any form of chromophores, but could emit intense yellow light under the excitation of near-ultraviolet (NUV) and blue light. A yellow-light phosphor integrated with a blue light-emitting diode (LED) to produce white light is the current mainstream of display technology, [18] although existing yellow phosphors that can be efficiently excited by NUV or blue light are very limited in number and range. A larger variety of advanced materials to add to the yellow phosphor YAG:Ce (YAG = yttrium aluminum garnet) is therefore in great demand. The intriguing optical properties of NTHU-4 and NTHU-6 has led us to explore a new class of color-conversion phosphors based on nanoporous host structures that have an intrinsic emission mechanism beyond our current understanding. [19] Existing inorganic yellow-light phosphors are all extrinsic illuminants. Before the two nanoporous structures were reported by us, no inorganic phosphate host that could emit yellow light but was not doped with lanthanide ions had been reported. The extraordinary intrinsic yellow emission was proposed to closely correlate with defects that result from the disorder in the large pores of the structure, firstly observed in NTHU-4 and later in NTHU-6. In the latter study, we had also speculated that the molecule 4,4'-trimethylenedipyridine (tmdp), the common template of both structures, acted as a sensitizer. To affirm and enhance the new phosphor system and rationalize an emission mechanism for the activator-free PL, it was imperative to produce further examples of these structures. In the pursuit of advanced and economical synthetic procedures for making new functional materials, we focused on the environmentally friendly deep eutectic solvent (DES). [20][21][22][23] Herein, we report the first nanosized channel structure successfully synthesized in a DES and also the first organically templated gallium oxalatophosphite compound, NTHU-7. It adopts an unprecedented organicinorganic hybrid nanotubular structure (Figure 1), which exhibits an even mor...

Dihydropyrimidinase (DHPase) is a key enzyme for pyrimidine degradation. DHPase contains a binuclear metal center in which two Zn ions are bridged by a posttranslationally carbamylated lysine. DHPase catalyzes the hydrolysis of dihydrouracil to N-carbamoyl-β-alanine. Whether 5-aminouracil (5-AU), a thymine antagonist and an anticancer drug that can block DNA synthesis and induce replication stress, can interact with DHPase remains to be investigated. In this study, we determined the crystal structure of Pseudomonas aeruginosa DHPase (PaDHPase) complexed with 5-AU at 2.1 Å resolution (PDB entry 7E3U). This complexed structure revealed that 5-AU interacts with Znα (3.2 Å), Znβ (3.0 Å), the main chains of residues Ser289 (2.8 Å) and Asn337 (3.3 Å), and the side chain of residue Tyr155 (2.8 Å). These residues are also known as the substrate-binding sites of DHPase. Dynamic loop I (amino acid residues Pro65-Val70) in PaDHPase is not involved in the binding of 5-AU. The fluorescence quenching analysis and site-directed mutagenesis were used to confirm the binding mode revealed by the complexed crystal structure. The 5-AU binding mode of PaDHPase is, however, different from that of 5-fluorouracil, the best-known fluoropyrimidine used for anticancer therapy. These results provide molecular insights that may facilitate the development of new inhibitors targeting DHPase and constitute the 5-AU interactome.

H 2 O (4), with clearly distinct but orderly increasing layer separations from 7.75 to 18.07 Å, have been prepared via hydrothermal routes and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic susceptibility or ion-exchange studies. The series possesses three unique layer topologies, but all contain V IV O 5 square pyramid, PO 4 tetrahedron, discrete dimers of V-O polyhedra, and 3-, 4-, 5-, and 8-membered rings. Structures 1 and 2 are V IV species, having the same layer topology but different amine cations. Compounds 3 and 4 are V IV /V V mixed valent, holding the same amine templates in varied inclined angles. Being similar to 1 and 2, the layer of 3 contains extra vanadate groups. In contrast, the layers in 4 are distinct and contain V V O 6 and V IV O 6 octahedra besides V IV O 5 square pyramid. It exhibits an interlayer d-spacing of 18.07 Å, the largest propped up by noncovalent intermediates between VPO layers. With an extremely low density of 1.71 g‚cm -3 , compound 4 also demonstrates the lightest layered material ever prepared in the V/P/O system. Structural relationship, template effect, factors controlling layer gaps, ion exchange, thermal stability, and magnetic properties are discussed.