The assembly of two tripyridinium‐tricarboxylate ligands and different metal ions leads to seven isostructural MOFs, which show novel 2D→2D supramolecular entanglement featuring catenane‐like ...interlocking of tricyclic cages. The MOFs show tripyridinium‐afforded and metal‐modulated photoresponsive properties. The MOFs with d10 metal centers (1‐Cd, 1‐Zn, 2‐Cd, 2‐Zn) show fast and reversible photochromism and concomitant fluorescence quenching, 1‐Ni displays slower photochromism but does not fluoresce, and 1‐Co and 2‐Co are neither photochromic nor fluorescent. It is shown here that the network entanglement dictates donor‐acceptor close contacts, which enable fluorescence originated from interligand charge transfer. The contacts also allow photoinduced electron transfer, which underlies photochromism and concomitant fluorescence response. The metal dependence in fluorescence and photochromism can be related to energy transfer through metal‐centered d‐d transitions. In addition, 1‐Cd is demonstrated to be a potential fluorescence sensor for sensitive and selective detection of UO22+ in water.
Organo‐originated and metal‐modulated photoresponsive properties were elucidated for a family of isostructural MOFs with tripyridinium‐tricarboxylate likers. Supramolecular entanglement between 2D networks dictates electron donor‐acceptor close contacts, which not only allow photoluminescence through interligand charge‐transfer excitation/emission but also cause photochromism through photoinduced electron transfer. Transition metal centers can weaken or prevent the photoresponsive properties because of energy transfer through d‐d transitions. The MOFs also show highly sensitive and selective fluorescence quenching response to UO22+ in water.
A two-dimensional Cd(
ii
) metal-organic framework (MOF) was constructed from a tris(pyridinium)-based hexacarboxylate zwitterionic ligand. The MOF shows a novel fashion of 2-fold 2D → 2D parallel ...entanglement. It is the entanglement that dictates close interlayer contacts between carboxylate (electron donor) and pyridinium (acceptor), which in turn impart the MOF with reversible photochromic properties through photoinduced electron transfer (PET). This is an extension of PET-based photochromism from bipyridinium to multipyridinium compounds. Thanks to the photoresponsive behaviour, the fluorescence of the MOF can be reversibly modulated or switched by photoirradiation. Besides, the fluorescence of the water-stable MOF in aqueous dispersion is very sensitive to nitrofuran antibiotics with high selectivity, and therefore the MOF is a good candidate of efficient and regenerable sensing material for determination of the antibiotics in water media.
Novel 2D → 2D entanglement affords close donor-acceptor contacts for electron transfer based photochromism and photomodulable fluorescence of a MOF, which also serves as a regenerable and sensitive luminescent sensor for nitrofuran antibiotics.
This study evaluated the association between admission MCV and preoperative deep vein thrombosis (DVT) in geriatric hip fractures.
Older adult patients with hip fractures were screened between ...January 2015 and September 2019. The demographic and clinical characteristics of the patients were collected at the largest trauma center in northwest China. MCV was measured at admission and converted into a categorical variable according to the quartile. Multivariate binary logistic regression and generalized additive model were used to identify the linear and nonlinear association between MCV and preoperative DVT. Analyses were performed using EmpowerStats and the R software.
A total of 1840 patients who met the criteria were finally enrolled and divided into four groups according to their MCV levels. The mean MCV was 93.82 ± 6.49 (80.96 to 105.91 fL), and 587 patients (31.9%) were diagnosed with preoperative DVT. When MCV was a continuous variable, the incidence of preoperative DVT increased with mean corpuscular volume. In the fully adjusted model, admission MCV was positively correlated with the incidence of preoperative DVT (OR: 1.03; 95% CI: 1.01-1.05; P = 0.0013). After excluding the effect of other factors, each additional 1fL of MCV increased the prevalence of preoperative DVT by 1.03 times as a continuous variable.
MCV was linearly associated with preoperative DVT in geriatric patients with hip fractures and could be considered a predictor of DVT risk. The MCV may contribute to risk assessment and preventing adverse outcomes in the elderly.
This study is registered on the website of the Chinese Clinical Trial Registry (ChiCTR: ChiCTR2200057323).
Sensory materials that show color and/or fluorescence changes in response to specific gases or vapors have important applications in many fields. Here, we report the postsynthetic preparation of ...novel sensory metal–organic frameworks (MOFs) and their multiple responsive properties. Through postsynthetic N-amination, the 2,2′-bipyridyl spacers in a Zr(IV) MOF are partially transformed into N-aminobipyridinium. The new MOF (Zr-bpy-A) shows chromic behavior toward ammonia and amines because the electron-deficient pyridinium groups form charge-transfer complexes with amino moieties. It also shows a unique chromic response to formaldehyde owing to the Schiff-base condensation with the N-amino groups. Furthermore, the N-amino group can be used to graft different polycyclic aromatic hydrocarbons, which endow the MOF with strong fluorescence of variable colors and afford a high-contrast fluorescence response to ammonia/amines and formaldehyde associated with the chromic response. The presence of the unquaternized bipyridyl group also leads to a fluorescence response to HCl. The multiple responsive behaviors hold appeal for applications in sensing, switching, and antifake marking, which are illustrated with a test paper and writing ink.
Achieving controllable fine-tuning of defects in catalysts at the atomic level has become a zealous pursuit in catalysis-related fields. However, the generation of defects is quite random, and their ...flexible manipulation lacks theoretical basis. Herein, we present a facile and highly controllable thermal tuning strategy that enables fine control of nanodefects via subtle manipulation of atomic/lattice arrangements in electrocatalysts. Such thermal tuning endows common carbon materials with record high efficiency in electrocatalytic degradation of pollutants. Systematic characterization and calculations demonstrate that an optimal thermal tuning can bring about enhanced electrocatalytic efficiency by manipulating the N-centered annulation-volatilization reactions and C-based sp
/sp
configuration alteration. Benefiting from this tuning strategy, the optimized electrocatalytic anodic membrane successfully achieves >99% pollutant (propranolol) degradation during a flow-through (~2.5 s for contact time), high-flux (424.5 L m
h
), and long-term (>720 min) electrocatalytic filtration test at a very low energy consumption (0.029 ± 0.010 kWh m
order
). Our findings highlight a controllable preparation approach of catalysts while also elucidating the molecular level mechanisms involved.
A novel metal–organic framework (MOF), formulated as Cd2(TTVTC)Cl2(H2O)3·2H2O (1), was synthesized from a tetracarboxylate ligand (TTVTC2–) functionalized with the thiazolothiazole extended viologen ...(TTV2+) fluorophore. The MOF features three-dimensional (10,3)-d frameworks with 6-fold interpenetration. The MOF exhibits reversible photochromism, due to photoinduced electron transfer from carboxylate to TTV2+. The photoactivity benefits from the electron donor–acceptor contacts enabled by mutual interpenetration of the frameworks. This is the first demonstration of photochromism in TTV2+ derivatives. In addition, the fluorescence arising from the TTV2+ fluorophore can be reversibly modulated during the photochromic process. The work demonstrates the great potential of extended viologen based ligands in the construction of MOFs with dual photomodulable optical properties, which could find future applications in photoelectronics.
The exchangeable counterions in ionic metal–organic frameworks (IMOFs) provide facile and versatile handles to manipulate functions associated with the ionic guests themselves and host–guest ...interactions. However, anion-exchangeable stable IMOFs combining multiple anion-related functions are still undeveloped. In this work, a novel porous IMOF featuring unique self-penetration was constructed from an electron-deficient tris(pyridinium)-tricarboxylate zwitterionic ligand. The water-stable IMOF undergoes reversible and single-crystal-to-single-crystal anion exchange and shows selective and discriminative ionochromic behaviors toward electron-rich anions owing to donor–acceptor interactions. The IMOFs with different anions are good ionic conductors with low activation energy, the highest conductivity being observed with chloride. Furthermore, integrating Lewis acidic sites and nucleophilic guest anions in solid state, the IMOFs act as heterogeneous and recyclable catalysts to efficiently catalyze the cycloaddition of CO2 to epoxides without needing the use of halide cocatalysts. The catalytic activity is strongly dependent upon the guest anions, and the iodide shows the highest activity. The results demonstrate the great potential of developing IMOFs with various functions related to the guest ions included in the porous matrices.
A new metal–organic framework (MOF), {(H 3 O)Eu (SBDB)(H 2 O) 2 } n (H 4 SBDB = 1,5-disulfo-benzene-2,4-dicarboxylic acid) ( 1 ), was successfully synthesized under solvothermal conditions. Ten ...central Eu 3+ ions are coordinated by the H 4 SBDB ligands and two coordination water molecules. The adjacent Eu 3+ ions are connected by oxygen atoms from carboxyl groups, forming a 1D chain. 1D chains are linked by H 4 SBDB ligands to induce a 2D infinitely extensible planar structure, and then connected by hydrogen bonds to form a 3D supernetwork structure. Complex 1 exhibits excellent thermal and chemical stability. AC impedance analysis shows that the highest proton conductivity of 1 reaches up to 1.0 × 10 −4 S cm −1 (338 K, 98% RH). Furthermore, complex 1 is an excellent luminescence-based sensor with high sensitivity and a low detection limit for ascorbic acid (AA) in aqueous solutions.
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