Energy transfer processes and structure of carboxymethyl cellulose-Tb/Eu nanocomplexes with color-tunable photoluminescence

A series of fluorescent nanocomplexes of carboxymethyl cellulose (CMC)/Terbium (Tb)- Europium (Eu) were successfully synthesized without introducing a second ligand. By adjusting the concentration of the coordinated ions, these nanocomplexes exhibit favorably visibly tunable luminescence properties with colors being able to change from green to red. The XPS analysis demonstrates the formation Tb(III)-O^2- and Eu(III)-O^2- between OH and COO^- in CMC and Tb³⁺ or Eu³⁺ ions, which is advantage for light absorption by UV-Vis spectroscopy and fluorescence spectroscopy. The ligand CMC plays a role in coordinating with terbium and europium ions, but also serves as an energy donor to these metal ions by antenna effect. Moreover, the energy transfer also occurred from terbium ions to europium ions in CMC matrix, which is responsible for the tunable luminescence properties of these complexes.

2D and 3D silver-based coordination polymers with thiomorpholine-4-carbonitrile and piperazine-1,4-dicarbonitrile: structure, intermolecular interactions, photocatalysis, and thermal behavior

The reaction of the thiomorpholine-4-carbonitrile and piperazine-1,4-dicarbonitrile ligands afforded four Ag(i) coordination polymers with excellent photocatalytic activity in the degradation of the mordant blue 9 dye.

In situ synthesis, crystal structures, topology and photoluminescent properties of poly[di-μ-aqua-di-aqua-[μ3-4-(1H-tetra-zol-1-id-5-yl)benzoato-κ4 O:O,O':O'']barium(II)] and poly[μ-aqua-di-aqua-[μ3-4-(1H-tetra-zol-1-id-5-yl)benzoato-κ4 O:O,O':O']strontium(II)]

Two alkaline-earth coordination compounds, [Ba(C8H4N4O2)(H2O)4] n , (I), and [Sr(C8H4N4O2)(H2O)3] n , (II), from the one-pot hydrolysis transformation of benzoyl chloride and the in situ self-assembled [2 + 3] cyclo-addition of nitrile are presented. These coordination compounds are prepared by reacting 4-cyano-benzoyl chloride with divalent alkaline-earth salts (BaCl2 and SrCl2) in aqueous solution under hydro-thermal conditions. The mononuclear coordination compounds (I) and (II) show the same mode of coordination of the organic ligands. The cohesion of the crystalline structures is provided by hydrogen bonds and π-stacking inter-actions, thus forming three-dimensional supra-molecular networks. The two compounds have a three-dimensional (3,6)-connected topology, and the structural differences between them is in the number of water mol-ecules around the alkaline earth metals. Having the same emission frequencies, the compounds exhibit photoluminescence properties with a downward absorption value from (I) to (II).

Crystal structure of catena-poly[(μ2-azido-κ2 N:N)(μ2-4-cyanobenzoato-κ2 O:O′)-(μ2-methanol-κ2 O:O)copper(II)], C9H8CuN4O3

C9H8CuN4O3, triclinic, P1̄ (no. 2), a = 6.3568(4) Å, b = 8.8323(6) Å, c = 10.8584(7) Å, α = 103.891(1)°, β = 94.868(1)°, γ = 105.453(1)°, V = 563.16(6) Å3, Z = 2, R gt(F) = 0.0245, wR ref(F 2) = 0.0701, T = 296(2) K.

A Lead Carboxylate-Azolate Metal-Organic Framework Based on Hexanuclear Clusters: Luminescence and Accelerating the Thermal Decomposition of Ammonium Perchlorate

A lead carboxylate-azolate framework, [Pb₃ (μ₄ -O)(L)₂ (H₂ O)] ⋅ 2H₂ O (1), has been constructed from the reaction of 2-methyl-4-(1H-tetrazol-5-yl) benzoic acid (H₂ L) and Pb(NO₃ )₂ under solvothermal conditions. Compound 1 contains an unprecedented hexanuclear cluster [Pb₆ (μ₄ -O)₂ (COO)₄ (CN₄ )₂ ], which as an 8-connected node is connected by 3-connected L linkers to give rise to a three-dimensional framework with an uncommon (3,8)-connected tfz-d; UO₃ topology. Framework 1 possesses strong solid-state yellow luminescence (563 nm), which stems from ligand-to-metal charge transfer (LMCT), however, the removal of water molecules in 1 lead to the significant luminescent decrease of the sample. Importantly, in the presence of 1, the thermal decomposition of ammonium perchlorate is significantly accelerated.

Two Highly Stable Luminescent Lead Phosphonates Based on Mixed Ligands: Highly Selective and Sensitive Sensing for Thymine Molecule and VO3 - Anion

Two luminescent lead phosphonates with two-dimensional (2D) layer and three-dimensional (3D) framework structure, namely, Pb₃[(L₁)₂(Hssc)(H₂O)₂] (1) and [Pb₂(L₂)_0.5(bts)(H₂O)₂]·H₂O (2) (H₂L₁ = O(CH₂CH₂)₂NCH₂PO₃H₂, H₄L₂ = H₂PO₃CH₂NH(C₂H₄)₂NHCH₂PO₃H₂, H₃ssc = 5-sulfosalicylic acid, NaH₂bts = 5-sulfoisophthalic acid sodium) have been prepared via hydrothermal techniques. The two compounds not only show excellent thermal stability but also remain intact in aqueous solution within an extensive pH range. Moreover, the atomic absorption spectroscopy analysis experiment indicates that there does not exist the leaching of Pb²⁺ ions from the lead phosphonates, which show they are nontoxic in aqueous solution. In compound 1, the Pb(1)O₄, Pb(2)O₇, Pb(3)O₄, and CPO₃ polyhedra are interlinked into a one-dimensional chain, which is further connected to adjacent chain by sharing the Hssc^2- to form a 2D layer. Interestingly, compound 1 as a highly selective and sensitive luminescent material can be used to detect the thymine molecule with a very low detection limit of 8.26 × 10^-7 M. In compound 2, the Pb(1)O₆ and Pb(2)O₅ polyhedra are interlinked into a dimer via edge sharing, which is further connected to adjacent dimer to form a tetramer via corner sharing, and such a tetramer is then interlinked into a 2D layer through bts^3- ligands; the adjacent 2D layers are finally constructed to a 3D structure by sharing the L₂ ^4- ligand. Compound 2 can be applied as an excellent luminescent sensor for sensing of VO₃ ^- anion. Furthermore, the probable fluorescent quenching mechanisms of the two compounds have also been studied.

A novel luminescent Pb(ii) – organic framework exhibiting a rapid and selective detection of trace amounts of NACs and Fe3+ with excellent recyclability

A novel Pb MOF used as a fluorescent probe for nitroaromatic explosives and Fe³⁺ shows high sensitivity and selectivity.

A highly selective and sensitive Zn(ii) coordination polymer luminescent sensor for Al3+and NACs in the aqueous phase

A novel coordination polymer Zn(DMA)(TBA) (1) (H₂TBA = 4-(1H-tetrazol-5-yl)-benzoic acid) features a unique two-dimensional (2D) network structure, exhibiting excellent luminescence and good stability in both water and other organic solvents.

Lanthanide Germanate Cluster Organic Frameworks Based on {Ln8Ge12} Clusters: From One-Dimensional Chains to Two-Dimensional Layers and Three-Dimensional Frameworks

Under hydrothermal conditions, six series of novel lanthanide (Ln) organogermanates (LnGs) [Ln8Ge12(μ3-O)24E12(H2O)16]·14H2O (Ln(3+) = Pr(3+), 1; Nd(3+), 2; Sm(3+), 3; Eu(3+), 4; Gd(3+), 5; one-dimensional (1-D) LnG cluster organic chain (LnGCOC)), {[Nd8Ge12(μ3-O)24E12(H2O)10](μ2-H2O)2[Nd8Ge12(μ3-O)24E12(H2O)16]}·18H2O (6, two-dimensional (2-D) planar LnG cluster organic layer (LnGCOL)), {[Ln2GeE(HO)2O(H2O)(CH3COO)2(CO3)]2[Ln8Ge12E12(μ3-O)24(H2O)10]}·6H2O (Ln(3+) = Pr(3+), 7; Nd(3+), 8; 2-D wave-shaped LnGCOL), [TbGeE(HO)2O(H2O)(pca)]2[Tb8Ge12E12(μ3-O)24(H2O)8]·10H2O (9, three-dimensional (3-D) LnG cluster organic framework (LnGCOF)), {([Nd(pza)2(H2O)2]2[Nd8Ge12E12(μ3-O)24(H2O)12])([Nd(pza)2]2[Nd8Ge12E12(Hpza)2(μ3-O)24(H2O)10])}·4OH·14H2O (10, 3-D LnGCOF), {[Nd8Ge12E12(μ3-O)24(H2O)10][Nd(pca)(pda)(H2O)]2}·12H2O (11, 3-D LnGCOF) and {[Nd8Ge12E12(μ3-O)24(H2O)10][Nd(pza)(pda)(H2O)]2}·12H2O (12, 3-D LnGCOF) (Hpca = 2-picolinic acid, H2pda = 2,6-pyridinedicarboxylic acid, Hpza = 2-pyrazinecarboxylic acid) were prepared by introducing the second auxiliary ligands into the organogermanate-lanthanide-oxide reaction system. The obtainment of these LnGs realized the utilization of the second auxiliary ligands inducing the assembly from 1-D LnGCOCs to 2-D LnGCOLs and 3-D LnGCOFs based on LnG cluster (LnGC) {Ln8Ge12E12(μ3-O)24(H2O)16}({Ln8Ge12}) units and Ln-organic complexes or organic ligand connectors. It should be noted that the well-organized structural constructions of 1-12 can be visualized as the gradual replacement of active water sites located at equatorial and polar positions on the hypothetical [Ln8Ge12(μ3-O)24E12(H2O)18] LnGC core with oxygen or nitrogen atoms from organic ligands. The solid-state luminescent properties of 2, 3, 4, 6, and 8-12 have been investigated at room temperature.

Zinc and cadmium complexes based on bis-(1H-tetrazol-5-ylmethyl/ylethyl)-amine ligands: structures and photoluminescence properties

Nine zinc and cadmium coordination compounds with bis-(1H-tetrazol-5-ylmethyl/ylethyl)-amine were synthesized and structurally characterized, and the fluorescent emission and fluorescence lifetime of complexes 1–9 have been investigated and discussed.

Hemi- and holo-directed lead(II) complexes in a soft ligand environment

To investigate the geometry and stereochemical activity of the lone pair at the lead atom, lead(ii) complexes () with one tripodal (L(1)), one dipodal (L(2)) boron-centred soft ligand and eight other small soft heterocyclic ligands, 2-mercaptobenzimidazole (L(3)), 2-mercapto-5-methylbenzimidazole (L(4)), 3-mercapto-1,2,4-triazole (L(5)H), 3-mercapto-4-methyl-1,2,4-triazole (L(6)), 2-mercapto-1,3,4-thiadiazole (L(7)H), 2-mercapto-5-methyl-1,3,4-thiadiazole (L(8)H), 5-mercapto-1-methyltetrazole (L(9)H) and 2-mercapto-4-phenylthiazole (L(10)H) were prepared. The structures of these complexes were elucidated on the basis of X-ray crystallography, elemental analyses as well as (1)H NMR, (1)H DOSY, (13)C NMR and (207)Pb NMR spectroscopy. The coordination numbers of these complexes vary from 4 to 8. The majority of the complexes are polymeric and possess a hemi-directed environment around the lead atoms. Solution studies revealed that most of the complexes are dissociated in highly polar solvents. Most of the complexes are emissive both under ambient conditions and at 77 K in the solid state. However, no obvious relationship between their solid state structures and luminescence behaviour with respect to the nature of the excited state could be identified.

Two three-dimensional cadmium(ii) coordination polymers based on 5-amino-tetrazolate and 1,2,4,5-benzenetetracarboxylate: the pH value controlled syntheses, crystal structures and luminescent properties

Two 3D cadmium(ii) coordination polymers have been prepared by controlling the pH values of the reaction mixture.

Limiting nuclearity in formation of polynuclear metal complexes through [2 + 3] cycloaddition: synthesis and magnetic properties of tri- and pentanuclear metal complexes

The cycloaddition reaction between [Ni(L)(N₃)] and different organonitriles afforded tetrazolate bridged tri- and pentanuclear nickel(ii) complexes.