Lotus-Root-like One-Dimensional Polymetallocages with Drastic Void Adaptability Constructed from 4,4′-Bis(1,2,4-triazol-1-ylmethyl)biphenyl and Zn(II) or Co(II) and Their Fluorescein Encapsulation Properties

The reaction of 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl (L) with Zn(NO3)2·6H2O or Co(NO3)2·6H2O in the presence of NH4PF6 in water−methanol or water−acetone produced both {[ZnL3](PF6)2(H2O)2}n (1) or {[CoL3](PF6)2(H2O)2}n (2). The metal ions in both complexes coordinate with six identical N atoms from six different ligands in an ideal octahedral environment where each ligand binds to two metal ions. Both complexes are one-dimensional triple-helical chains each containing an empty lotus-root-structured polymetallocage. The metallocage in 1 is fully empty, while the cage in 2 contains two water molecules. However, metallocages in 1 have a void volume of ∼200 Å3, which is much smaller than the 1020 Å3 void in 2. The void in 2 is comparable to the size of fluorescein. Both complexes are capable of encapsulating fluorescein anion in pH 9 aqueous solution to form {C20H10O5 ⊂ [ML3]}n, where C20H10O52− is fluorescein dianion, and M is Zn or Co. The encapsulation occurs via anion exchange. The cages in 1 are increased drastically to fit the size of fluorescein due to the flexibility of ligand, while in 2 the cages have no discernible change after fluorescein encapsulation due to a perfect match between the cavity size in 2 and the fluorescein. Fluorescein encapsulated 1 and 2 have identical powder X-ray diffraction patterns, indicating that they have similar structures after fluorescein encapsulation. Both complexes show fluorescence after fluorescein encapsulation

Lotus-Root-like One-Dimensional Polymetallocages with Drastic Void Adaptability Constructed from 4,4′-Bis(1,2,4-triazol-1-ylmethyl)biphenyl and Zn(II) or Co(II) and Their Fluorescein Encapsulation Properties

The reaction of 4,4′-bis(1,2,4-triazol-1-ylmethyl)biphenyl (L) with Zn(NO3)2·6H2O or Co(NO3)2·6H2O in the presence of NH4PF6 in water−methanol or water−acetone produced both {[ZnL3](PF6)2(H2O)2}n (1) or {[CoL3](PF6)2(H2O)2}n (2). The metal ions in both complexes coordinate with six identical N atoms from six different ligands in an ideal octahedral environment where each ligand binds to two metal ions. Both complexes are one-dimensional triple-helical chains each containing an empty lotus-root-structured polymetallocage. The metallocage in 1 is fully empty, while the cage in 2 contains two water molecules. However, metallocages in 1 have a void volume of ∼200 Å3, which is much smaller than the 1020 Å3 void in 2. The void in 2 is comparable to the size of fluorescein. Both complexes are capable of encapsulating fluorescein anion in pH 9 aqueous solution to form {C20H10O5 ⊂ [ML3]}n, where C20H10O52− is fluorescein dianion, and M is Zn or Co. The encapsulation occurs via anion exchange. The cages in 1 are increased drastically to fit the size of fluorescein due to the flexibility of ligand, while in 2 the cages have no discernible change after fluorescein encapsulation due to a perfect match between the cavity size in 2 and the fluorescein. Fluorescein encapsulated 1 and 2 have identical powder X-ray diffraction patterns, indicating that they have similar structures after fluorescein encapsulation. Both complexes show fluorescence after fluorescein encapsulation

Coordination Polymers of 1,3,5-Tris(triazol-1-ylmethyl)-2,4,6-trimethylbenzene: Synthesis, Structure, Reversible Hydration, Encapsulation, and Catalysis Oxidation of Diphenylcarbonohydrazide

Eight coordination polymers {[Co3(L)2(H2O)6Cl6]·4H2O}n (1), {[Co(L)2Cl2]·13H2O}n (2), {[Cu3(L)2(H2O)6Cl6]·4H2O}n (3), {[Cu(L)2Cl2]·12H2O}n (4), {[Zn(L)2(H2O)2](NO3)2·4H2O}n (5), {[Zn(L)2(H2O)2](PF6)2·6H2O}n (6), {[ZnL(mal)]·3H2O}n (7), and {[Zn3(L)2(fum)3(H2O)6]·2H2O}n (8) were synthesized by reactions of the flexible tripodal ligand 1,3,5-tris(triazol-1-ylmethyl)-2,4,6-trimethylbenzene (L) and/or fumaric acid (H2fum)/malonic acid (H2mal), with corresponding metal salts, respectively. The structures of these polymers were established by elemental analysis, IR, powder and single-crystal X-ray diffraction analysis. Complexes 1 and 3 had an infinite two-dimensional (2D) honeycomb network. L as a cis-tridentate ligand coordinated to metal ions up and down alternatively. Complexes 2 and 4 possessed a one-dimensional (1D) chain hinged structure. L was a cis-bidentate ligand. Complexes 5 and 6 had a 2D network structure with (4,4) topology. L was a trans-bidentate ligand in 5, while in 6, L adopted a cis-configuration coordinated to metal ion bidentately. Complex 7 had a wavy 2D structure. L adopted a trans-configuration coordinated ion in the c-direction, while the malonate anion coordinated to metal ions in the b-direction in left- and right-helix alternatively. Complex 8 had an unusual 2D to three-dimensional (3D) interpenetration network structure. L was in trans-configuration coordinated to metal ions tridentately in the bc plane to form a ladder structure, and fumarate anion bridged the ladder in the a-axis to form a porous 2D coordination polymer. Adjacent 2D coordination polymers penetrated each other in the c-direction to form a 3D coordination with void dimensions consisting of 11 Å rhombic channels. The structures of 1 and 2 (or 3 and 4) indicate ligand/metal ratios had a significant influence on the structures of coordination polymers. The distinct structures of all these complexes demonstrated that the counteranions played an important role in the construction of coordination polymers. The isostructure between complexes 1 and 3, 2 and 4, and 5 indicate that the metal centers did not affect the structure of the complexes. Complex 8 with the characteristic of hydrophilic carboxylate groups and hydrophobic L was capable of absorbing water reversibly under 50 °C and encapsulating guest molecules, such as curcumin, diphenylcarbonohydrazide, and phenylfluorone, to form {(guest molecule)x ⊂ 8}n. (where x = 0.2–0.4). The encapsulation behavior of 8 had been studied by elemental analysis, IR, thermogravimetric analysis (TG), and X-ray powder diffraction patterns (PXRD). Complex 8 could heterogeneously catalyze the oxidation of diphenylcarbonohydrazide in the presence of H2O2 in ethanol effectively. The oxidation process was facile, efficient, and environmental friendly

Coordination Polymers of 1,3,5-Tris(triazol-1-ylmethyl)-2,4,6-trimethylbenzene: Synthesis, Structure, Reversible Hydration, Encapsulation, and Catalysis Oxidation of Diphenylcarbonohydrazide

Eight coordination polymers {[Co3(L)2(H2O)6Cl6]·4H2O}n (1), {[Co(L)2Cl2]·13H2O}n (2), {[Cu3(L)2(H2O)6Cl6]·4H2O}n (3), {[Cu(L)2Cl2]·12H2O}n (4), {[Zn(L)2(H2O)2](NO3)2·4H2O}n (5), {[Zn(L)2(H2O)2](PF6)2·6H2O}n (6), {[ZnL(mal)]·3H2O}n (7), and {[Zn3(L)2(fum)3(H2O)6]·2H2O}n (8) were synthesized by reactions of the flexible tripodal ligand 1,3,5-tris(triazol-1-ylmethyl)-2,4,6-trimethylbenzene (L) and/or fumaric acid (H2fum)/malonic acid (H2mal), with corresponding metal salts, respectively. The structures of these polymers were established by elemental analysis, IR, powder and single-crystal X-ray diffraction analysis. Complexes 1 and 3 had an infinite two-dimensional (2D) honeycomb network. L as a cis-tridentate ligand coordinated to metal ions up and down alternatively. Complexes 2 and 4 possessed a one-dimensional (1D) chain hinged structure. L was a cis-bidentate ligand. Complexes 5 and 6 had a 2D network structure with (4,4) topology. L was a trans-bidentate ligand in 5, while in 6, L adopted a cis-configuration coordinated to metal ion bidentately. Complex 7 had a wavy 2D structure. L adopted a trans-configuration coordinated ion in the c-direction, while the malonate anion coordinated to metal ions in the b-direction in left- and right-helix alternatively. Complex 8 had an unusual 2D to three-dimensional (3D) interpenetration network structure. L was in trans-configuration coordinated to metal ions tridentately in the bc plane to form a ladder structure, and fumarate anion bridged the ladder in the a-axis to form a porous 2D coordination polymer. Adjacent 2D coordination polymers penetrated each other in the c-direction to form a 3D coordination with void dimensions consisting of 11 Å rhombic channels. The structures of 1 and 2 (or 3 and 4) indicate ligand/metal ratios had a significant influence on the structures of coordination polymers. The distinct structures of all these complexes demonstrated that the counteranions played an important role in the construction of coordination polymers. The isostructure between complexes 1 and 3, 2 and 4, and 5 indicate that the metal centers did not affect the structure of the complexes. Complex 8 with the characteristic of hydrophilic carboxylate groups and hydrophobic L was capable of absorbing water reversibly under 50 °C and encapsulating guest molecules, such as curcumin, diphenylcarbonohydrazide, and phenylfluorone, to form {(guest molecule)x ⊂ 8}n. (where x = 0.2–0.4). The encapsulation behavior of 8 had been studied by elemental analysis, IR, thermogravimetric analysis (TG), and X-ray powder diffraction patterns (PXRD). Complex 8 could heterogeneously catalyze the oxidation of diphenylcarbonohydrazide in the presence of H2O2 in ethanol effectively. The oxidation process was facile, efficient, and environmental friendly

Fluorescence intensity (λ_em = 483 nm) of compound 1-Cu²⁺ to various amino acids: the first bars represent the fluorescence intensity upon addition of 4 equivalents of various amino acids; the second bars represent the fluorescence intensity after subsequent addition of 2 equivalents of GSH to the non-sulfhydryl amino acids solution, respectively.

<p>Fluorescence intensity (λ_em = 483 nm) of compound 1-Cu²⁺ to various amino acids: the first bars represent the fluorescence intensity upon addition of 4 equivalents of various amino acids; the second bars represent the fluorescence intensity after subsequent addition of 2 equivalents of GSH to the non-sulfhydryl amino acids solution, respectively.</p

Synthesis procedures of the thiols probe (compound 1-Cu²⁺).

<p>Synthesis procedures of the thiols probe (compound 1-Cu²⁺).</p

Fluorescence responses of compound 1-Cu²⁺ (10 μmol/L) in CH₃CN:H₂O (3:2, v/v) PBS solution upon the addition of increasing GSH.

Insert: fluorescence titration profile at 483 nm upon the addition of GSH (excited at 445 nm).</p

UV-vis titration of compound 1 (10 μmol/L) in CH₃CN:H₂O (3:2, v/v) PBS solution upon addition of Cu²⁺.

<p>Inset: UV-vis titration profile of compounds <b>1</b> upon addition of Cu²⁺, the absorption was recorded at 480 nm.</p

Fluorescence emission spectra of compound 1 (10 μmol/L) in CH₃CN:H₂O (3:2, v/v) PBS solution with successive addition of Cu²⁺.

<p>Insert: fluorescence titration profile at 483 nm upon the addition of Cu²⁺ (excited at 445 nm).</p

Bimetallic Au and Pd Nanoparticles Modified WO₃ Nanosheets for Enhancing the Sensitivity and Selectivity of Formaldehyde Assessment in Aquatic Products

Formaldehyde, a common illegal additive in aquatic products, poses a threat to people’s health and lives. In this study, a novel metal oxide semiconductor gas sensor based on AuPd-modified WO3 nanosheets (NSs) had been developed for the highly efficient detection of formaldehyde. WO3 NS modified with 2.0% AuPd nanoparticles showed a higher response (Ra/Rg = 94.2) to 50 ppm of formaldehyde at 210 °C, which was 36 times more than the pristine WO3 NS. In addition, the AuPd/WO3 gas sensor had a relatively short response/recovery time of 10 s/9 s for 50 ppm of formaldehyde at 210 °C, with good immunity to other interfering gases and good stability for formaldehyde. The excellent gas-sensitive performance was attributed to the chemical sensitization of Au, the electronic sensitization of Pd, and the synergistic effect of bimetallic AuPd, which facilitated the recognition and response of formaldehyde molecules. Additionally, the high sensitivity and broad application prospect of the 2.0% AuPd/WO3 NS composite-based sensor in real sample detection were also confirmed by using the above sensor for the detection of formaldehyde in aquatic products such as squid and shrimp