New Sm (III) and Nd (III) complexes: Synthesis, structural characterization and fluorescent sensing of nitro‐aromatic compounds

3D ZnII-Based coordination polymer: Synthesis, structure and fluorescent sensing property for nitroaromatic compounds

A water-stable Zn^II-based coordination polymer (CP) with excellent photophysical behavior, namely [Zn₂L(atez)(H₂O)₂] (compound 1; H₃L = 4-(2',3'-dicarboxylphenoxy); atez = 5-aminotetrazole), was successfully prepared by the solvothermal reaction of Zn ions with a π-conjugated and semi-rigid multicarboxylate ligand H₃L in the presence of N-containing linker atez. Compound 1 displays a hierarchically pillared three-dimensional (3D) (3,4,5)-connected (4·6²) (4²·6⁴) (4³·6⁴·8³) net which is based on two-dimensional (2D) multicarboxylate- Zn^II layers strutted by the atez ligands. Sensing investigations of compound 1 reveal that this material can selectively and sensitively detect nitroaromatic compounds in water suspension through fluorescence quenching effect. In particular, it is worth noting that it shows highly specific detection of nitrobenzene (NB) and 2,4,6-trinitrophenol (TNP) with remarkable quenching constants (K_SV = 7.5 × 10⁴ M^-1 for NB and K_SV = 1.9 × 10⁵ M^-1 for TNP) and low limit of detection (LOD = 0.93 μM for NB and LOD = 0.36 μM for TNP). Investigations reveal that the probable mechanisms for such sensing processes are the concurrent presence of fluorescence resonance energy transfer (FRET) as well as photoinduced electron transfer (PET) between the CP and nitroaromatic molecules. This work not only offers an effective route to improve the application of fluorescent CPs but also provide one novel probable fluorescence probe for nitroaromatic compounds.

The preparation of 2,2'-bithiophene-based conjugated microporous polymers by direct arylation polymerization and their application in fluorescence sensing 2,4-dinitrophenol

In this paper, we report the synthetic strategy of direct arylation polymerization (DAP) for four 2,2'-bithiophene-based conjugated microporous polymers (the 2,2'-BTh-based CMPs) by coupling 2,2'-bithiophene with the building blocks containing bromine. Compared to conventional coupling polymerization, this synthetic scheme is simple, facile and atomically efficient owing to neither preactivating the C-H bonds in 2,2'-bithiophene using organometallic reagents nor synthesis of complex thiophene-based building blocks. The resulting 2,2'-BTh-based CMPs exhibit excellent thermal stability, high specific surface areas, and good microporosity. Their specific surface areas are higher than that of other previously reported CMPs prepared with DAP. The four 2,2'-BTh-based CMPs can be utilized for multicolor fluorescence sensing of 2,4-dinitrophenol (DNP) with the high sensitivity and selectivity. The sensitivities appear to increase with the degree of structural distortion.

Ultrasonic assisted preparation of ultrafine Pd supported on NiFe-layered double hydroxides for p-nitrophenol degradation

NiFe-layered double hydroxide (NiFe-LDH)-loaded ultrafine Pd nanocatalysts (Pd/NiFe-LDHs) were prepared by a facile ultrasonic-assisted in situ reduction technology without any stabilizing agents or reducing agents. Pd/NiFe-LDHs were characterized by FT-IR, XRD, XPS, and TEM. PdNPs are uniformly dispersed on NiFe-LDHs with a particle size distribution of 0.77-2.06 nm and an average particle size of 1.43 nm. Hydroxyl groups in Fe-OH and Ni-OH were dissociated into hydrogen radicals (·H) excited by ultrasound, and ·H reduced Pd²⁺ to ultrafine PdNPs. Then, Pd was coordinated with O in Ni-O and Fe-O, which improved the stability of the catalysts. Pd/NiFe-LDHs completely degraded 4-NP in 5 min, and the TOF value was 597.66 h^-1, which was 16.7 times that of commercial Pd/C. The 4-NP conversion rate remained at 98.75% over Pd/NiFe-LDHs after 10 consecutive catalytic cycles. In addition, the catalyst also has high catalytic activity for the reduction of Congo red, methylene blue, and methyl orange by NaBH₄.

Five Dinuclear Lanthanide Complexes Based on 2,4-dimethylbenzoic Acid and 5,5'-dimethy-2,2'-bipyridine: Crystal Structures, Thermal Behaviour and Luminescent Property

A series of new complexes, [Ln (2,4-DMBA)3(5,5'-DM-2,2'-bipy)]2 (Ln = Sm(1), Eu (2)), [Pr (2,4-DMBA)3 (5,5'-DM-2,2'-bipy)]2·0.5(C2H5OH) (3), [Ln (2,4-DMBA)3 (5,5'-DM-2,2'-bipy)]2·0.5(2,4-DMBAH)·0.25(5,5'-DM-2,2'-bipy) (Ln = Tb (4), Dy (5)) (2,4-DMBA = 2,4-dimethylbenzoate, 5,5'-DM-2,2'-bipy = 5,5'-dimethy-2,2'-bipyridine) were synthesized via hydrothermal reaction conditions. The complexes were characterized through elemental analysis, Infrared spectra (IR), Raman (R) spectra, UV-Vis spectra, single X-ray diffraction. Single crystal data show that complexes 1-5 are binuclear complexes, but they can be divided into three different crystal structures. The thermal decomposition mechanism of complexes 1-5 were investigated by the technology of simultaneous TG/DSC-FTIR. What's more, the luminescent properties of complexes 1-2 and 4 were discussed, and the luminescence lifetime (τ) of complexes 2 and 4 were calculated.