Amino-Functionalized NDI-Based MOFs as Unusual "Turn On" and "Turn Off" Fluorescent Sensors for Phenolic Pollutants with Double Solvent Channel Response and Iodine Adsorbents.

Regulating mixed ligands to change the functional properties of metal-organic frameworks (MOFs) has been an important topic; especially, the structural changes have significant implications for the transformation of sensing response in different solvent channels. Herein, two [Cd (DPNDI) (NH2-BDC)0.5(NO3)]·2.25DMF (1) and [Cd(DPNDI)(NH2-AIPA)]·0.5DMF (2) (DPNDI = N,N-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide, NH2-BDC = 2-amino terephthalic acid, NH2-AIPA = 5-aminoisophthalic acid) were synthesized by the solvothermal method. Structural analysis shows that complex 1 has a two-dimensional planar network structure and complex 2 exhibits a three-dimensional network structure, endowing its potential as an efficient fluorescence sensor for phenolic compound detection under different solvent environments. Both complexes showed high fluorescence quenching sensitivity to phenolics in a water medium. Conversely, complex 1 showed a fluorescence enhancement response to phenolic pollutants in an ethanol system with significantly low detection limits and recyclability. The detection limits were 0.58 µM for TNP, 1.3 µM for DNP, and 2.43 µM for PCP. In addition, the uncoordinated amino groups in the complexes promote them to exhibit excellent iodine adsorption performance. Especially, complex 2 can serve as an adsorbent for iodine in cyclohexane solution with better adsorption efficiency than that of complex 1, and its adsorption capacity can reach 505 mg/g. The mixed ligands regulation strategy of NDI-based MOFs will open up an effective avenue for the conversion of fluorescence signals in dual-solvent channels and play simultaneously important roles in multiple applications.

Design and Construction of the Uranyl Coordination Polymer with Multifunction Stimulus Response: Fluorescent Sensors for Halide Ions and Photochromism.

It can provide ideas for the use of uranium elements in the treatment of spent fuel from nuclear wastewater to explore the application potential of uranium element. Thus, it is necessary to research the structure and properties of a novel uranyl coordination polymer (CP) for uranium recovery and reuse. Herein, we designed and prepared a new uranyl CP U-CMNDI based on UO22+ and H2CMNDI (H2CMNDI = N, N'-bis(carboxymethyl)-1,4,5,8-naphthalenediimide). Structural analysis shows that two uranyl ions are connected by two parallel deprotonated CMNDI ligands to form a discrete uranyl dimer structure. U-CMNDI can act as a potential stimulus-responsive halide ion sensor by a fluorescence "turn on" response in water. The limit of detection for fluoride (F-), bromide (Br-), iodide (I-), and chloride (Cl-) is 5.00, 5.32, 5.49, and 5.73 µM, respectively. The fluorescence "turn on" behavior is based on the photoinduced electron transfer (PET) mechanism between halide ions and electron-deficient NDI cores. In addition, U-CMNDI demonstrates a color response to ultraviolet light, exhibiting reversible photochromic behavior with a notable color change. The color change mechanism can contribute to the PET process and the radical process.

3D-printed titanium porous prosthesis combined with the Masquelet technique for the management of large femoral bone defect caused by osteomyelitis.

BACKGROUND: The treatment of infected bone defects remains a clinical challenge. With the development of three-dimensional printing technology, three-dimensional printed implants have been used for defect reconstruction. The aim of this study was to investigate the clinical outcomes of three-dimensional printed porous prosthesis in the treatment of femoral defects caused by osteomyelitis. METHODS: Eleven patients with femoral bone defects following osteomyelitis who were treated with 3D-printed porous prosthesis at our institution between May 2017 and July 2021, were included. Eight patients were diagnosed with critical-sized defects, and the other three patients were diagnosed with shape-structural defects. A two-stage procedure was performed for all patients, and the infection was eradicated and bone defects were occupied by polymethylmethacrylate spacer during the first stage. The 3D-printed prosthesis was designed and used for the reconstruction of femoral defects in the second stage. Position of the reconstructed prostheses and bone growth were measured using radiography. The union rate, complications, and functional outcomes at the final follow-up were assessed. RESULTS: The mean length of the bone defect was 14.0 cm, union was achieved in 10 (91%) patients. All patients showed good functional performance at the most recent follow-up. In the critical-sized defect group, one patient developed a deep infection that required additional procedures. Two patients had prosthetic dislocations. Radiography demonstrated good osseous integration of the implant-bone interface in 10 patients. CONCLUSION: The 3D printed prostheses enable rapid anatomical and mechanically stable reconstruction of extreme femur bone defects, effectively shortens treatment time, and achieves satisfactory clinical outcomes.

Multiple spinal gas in an 86-year-old diabetic man.

Although spinal gas is common and can be found in various sites and lesions, it should prompt a search for the underlying cause, given that the clinical significance of ectopic gas varies from benign to scary. Spinal gas can occur in the traumatic, iatrogenic, degenerative, osteoporotic, infectious, or neoplastic lesions. The imaging similarity may cause the misdiagnosis or delayed diagnosis which sometimes requires immediate attention. The pattern of gas distribution, detailed appearance, clinical history, and findings on examination can provide clues to diagnosis. Computed tomography is the best method for sensitive detection of gas.

Stimulus-Responsive Lanthanide MOF Materials Encapsulated with Viologen Derivatives: Characterization, Photophysical Properties and Sensing on Nitrophenols.

Viologens (1,1'-disubstituted 4,4'-bipyridyls) possessing electron-deficient properties and redox activity are a class of suitable chromophores to assemble metal-organic hybrid photochromic materials. Thus, viologen-functionalized metal-organic frameworks (MOFs) have attracted much attention for their photochromic properties; however, the syntheses of lanthanide-viologen hybrid crystalline photochromic materials still face many challenges. For example, the structures and properties of the final products are difficult to predict and are limited by molecular configurations. In this work, host-guest composite-material Ln-NH2 BDC-pbpy MOFs were constructed by encapsulating viologen derivative pbpyCl2 . The pbpy2+ moieties are uniformly embed by their π-π conjugation in the pores of the 3D structure by electrostatic interactions. Due to the encapsulation of the chromophore pbpy2+ moieties, Ln-NH2 BDC-pbpy MOFs have reversible photochromic properties: they can change color after irradiation and can return to the original color after being protected from light or heating. Interestingly, the fluorescence intensity decreases with illumination time and recovers in the dark. As a result, Ln-NH2 BDC-pbpy MOFs show both photochromic and photomodulated fluorescence. Based on the outstanding fluorescence performance of the Ln-NH2 BDC-pbpy MOFs, they also show a wonderful effect for detecting nitrophenols, especially TNP.

Multiple Stimulus Response 2D Framework Constructed by a Flexible Cyclotriphosphazene-Derived Carboxylic Acid Linker: Synthesis, Characterization, and Fluorescence Sensing to Phenolic Pollutants and Small-Molecule Drugs.

Hexachlorocyclotriphosphazene is one of the most representative phosphazene compounds which have been proved to have broad application prospects in many fields. However, it is an emerging research perspective to combine cyclotriphosphazene-derived polycarboxylic acid compounds with lanthanides for the construction of Tb-DPCP metal-organic framework (MOF) materials. Herein, a Tb-DPCP MOF, (CH3)2NH2[Tb3(HDPCP)(DMF)(H2O)3]·6DMF (1), was successfully prepared via the reaction of H12HDPCP [hexa(4-carboxyphenoxy) cyclotriphosphazene] and Tb(NO3)3·6H2O under the solvothermal condition. Through fluorescence sensing experiments, it was found that both nitrophenols and chlorophenols could cause the fluorescence quenching of compound 1. At the same time, the compound also exhibited nice trace detection ability for small-molecule drugs (moxifloxacin hydrochloride, balsalazide disodium, and colchicine); the limits of detection were all lower than 0.2 µM. These experimental results fully demonstrated the potential application value of 1 as a multifunctional fluorescent sensor.

Preparation of Naphthalenediimide-Decorated Electron-Deficient Photochromic Lanthanide (III)-MOF and Paper Strip as Multifunctional Recognition and Ratiometric Luminescent Turn-On Sensors for Amines and Pesticides.

Detecting toxic amine and pesticide contamination in the environment is one of the most pressing issues for environmental sustainability. In this work, two 3D Ln-BINDI complexes [Ln = Eu (1), Sm (2); H4BINDI (N, N'-bis(5-isophthalic acid)-1,4,5,8-naphthalenediimide)] have been designed and synthesized. Crystal structure of [Eu2(BINDI) (NO3)2(DMA)4]·2DMA (complex 1) featuring the lvt topology was determined by X-ray single-crystal diffraction. A multi-functional ratiometric luminescence sensor benefitting from π-electron-deficient NDI moieties and f-f transition characteristics of lanthanide Eu3+ ions for complex 1 has been investigated. Markedly, complex 1 exhibit completely different selective fluorescence ratiometric turn-on responses and pretty high sensitivity behaviors to aromatic amines (OPD), aliphatic amines (n-BA), and pesticides (TBZ), respectively, which are driven by interactions between the electron-donating amino group and acceptor NDI site, contributing to complex 1 as a potential ratiometric luminescent turn-on sensor for practical environmental applications. A PVA/1@paper strip can be used as a potential size selectivity sensor for the practical detection of aliphatic amine vapors in the environment through visual chromic fluorescence enhancement. Because NDIs can undergo one-electron reduction to form stable NDI· free radicals, solid complex 1 can visually distinguish different kinds of amines by selective amine-specific color changes and has the photochromic property of erasable inkless printing.

RhB-Embedded Mn-MOF with Cyclotriphosphazene Skeleton as Dual-Emission Sensor for Putrescine as well as Smart Fluorescent Response of Aromatic Diamines and Nitrophenol.

Luminescent metal-organic framework composites with multiple luminescence emissions have been efficient sensing platforms. Herein, a fluorescent sensor (RhB@1-0.4) with dual-emission fluorescence properties was prepared by introducing rhodamine B (RhB) into the framework of complex 1, [Mn2.5(HCPCP)(H2O)4]·(CH3CN)0.5 [HCPCP = hexa-(4-carboxyl-phenoxy)-cyclotriphosphazene and CH3CN = acetonitrile), which is a novel crystalline two-dimensional (2D) coordinated organic framework material. It is a highly desirable material, realizing a ratiometric fluorescence response to putrescine with a high signal-to-noise ratio, and the detection limit can be as low as 6.8 µM. In addition, RhB@1-0.4 exhibited a better fluorescent sensing performance for aromatic diamines and nitrophenols compared with that of complex 1. It is a potential functionalized MOF material for the application of multichannel fluorescence sensing.

TsOH-catalyzed acyl migration reaction of the Bz-group: innovative assembly of various building blocks for the synthesis of saccharides.

We developed an efficient method to achieve the regioselective acyl migration of benzoyl ester. In all the cases, the reactions required only the commercially available organic acid catalyst TsOH·H2O. This method enables the benzoyl group to migrate from secondary groups to primary hydroxyl groups, or from equatorial secondary hydroxyl groups to axial hydroxyl groups. The 1,2 or 1,3 acyl migration would potentially occur via five- and six-membered cyclic ortho acid intermediates. A wide range of orthogonally protected monosaccharides, which are useful intermediates for the synthesis of natural oligosaccharides, were synthesized. Finally, to demonstrate the utility of the method, a tetrasaccharide portion from a mycobacterial cell wall polysaccharide was assembled.

Silencing of circ-NT5C2 retards the progression of IL-1ß-induced osteoarthritis in an in vitro cell model by targeting the miR-142-5p/NAMPT axis.

Osteoarthritis (OA) is a degenerative disease that occurs mostly in the elderly, and its specific pathogenesis is still unknown, but recent studies have found that circular RNA generally display aberrant expression in OA. Our study explored the expression characteristics and mechanism of action of circ-NT5C2 in OA. Circ-NT5C2, microRNA-142-5p (miR-142-5p), and nicotinamide phosphoribosyltransferase (NAMPT) mRNA levels were measured using RT-qPCR. Western blot was employed to assess the protein level of NAMPT and extracellular matrix (ECM) production-related markers. The viability, proliferation, apoptosis and inflammation were examined using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry, and enzyme-linked immunosorbent assay, respectively. Relationship between miR-142-5p and circ-NT5C2 or NAMPT was demonstrated by dual-luciferase reporter system and RNA immunoprecipitation assay. We reported that circ-NT5C2 and NAMPT were greatly upregulated, and miR-142-5p level was constrained in OA tissues and in a cell model. Circ-NT5C2 silencing alleviated IL-1ß-induced inhibitory effects on chondrocyte proliferation and ECM generation, meanwhile the promotional role of IL-1ß on chondrocyte apoptosis and inflammation was also weakened. The targeting relationship of miR-142-5p with either circ-NT5C2 or NAMPT was confirmed. Knockdown of miR-142-5p reversed the suppressive effects of circ-NT5C2 silencing on the OA progression in vitro, and NAMPT overexpression also attenuated the effects of miR-142-5p upregulation in an OA cell model. Collectively, circ-NT5C2 accelerated the OA process by targeting the miR-142-5p/NAMPT axis. This study provides valuable information to find a better treatment for OA.

Design, synthesis and biological evaluation of 1,3,4-triazole-3-acetamide derivatives as potent neuraminidase inhibitors.

Neuraminidase (NA) is an ideal target for the development of anti-influenza drugs. In this paper, ZINC06057848 was screened out as a hit compound by docking-based virtual screening and molecular dynamics (MD) simulation. The modification and optimization of hit ZINC06057848 resulted in the discovery of a series of novel 1,3,4-triazole-containing NA inhibitors (5a-5j). Compound 5c exerts the best inhibitory activity (IC50 = 0.11 µM) against NA, which is comparable to the positive control oseltamivir carboxylate (OSC) (IC50 = 0.10 µM). Molecular docking analysis indicates that the good efficacy of inhibitor 5c may be attributed to the furan and triazole rings extending into 430-cavity and the ethylbenzene part occupying the active site. The results of this work may help in the development of new NA inhibitors.

Stimuli-Responsive Naphthalenediimide Cd-MOFs Tuned by Different Aliphatic Dicarboxylic Acids with Extended Spacers.

A series of novel Cd metal-organic frameworks (MOFs) (1-9) with different extended spacers with seven kinds of the aliphatic dicarboxylic acids as secondary building linkers based on N,N'-di(4-pyridylacylamino)-1,4,5,8-naphthalenediimide (NDI-A) have been designed and synthesized by changing the volume ratio of solvents under solvothermal conditions. In addition, the secondary building linkers of aliphatic dicarboxylic acids have different spacer lengths, resulting in different structures of complexes 1-9. So, their packing structures are affected by the degree of distortion of the NDI-A ligand, the different aliphatic dicarboxylic acids ligands, and the hydrogen-bonding patterns. Complexes 1-9 showed stimuli-responsive emission tuned by different aliphatic dicarboxylic acids with extended length spacers under UV light irradiation, accompanied by the color change from light orange to dark brown, and achieved reversible photochromic under heating, which indicates that they could serve as secret erasable inks. Moreover, complexes 1-9 exhibited selective vaporchromic behavior to methylamine (MA), and the vaporchromic sample could be recovered after washing with MeOH. It is worth noting that the preparation of poly(vinyl alcohol) (PVA)-NDI-MOF films enables the photochromic and vaporchromic properties of complexes 1-9 to apply in practice. In addition, complexes 1-9 exhibited good fluorescence properties as sensing probes toward 2,4,6-trinitrophenol (TNP) with lower limits of detection. In short, this work provides a broad field to explore the creative NDI-MOF materials with photoactive and luminescent properties.

Construction of Large-Scale Conjugated Functionalized Cyclotriphosphazene Lanthanide Framework for Selective Sensing of Volatile Organic Compounds and Assembly of Color-Tunable Dye-Encapsulated Composites.

A flexible functionalized cyclotriphosphazene hexacarboxylic acid, hexakis(4-carboxylatephenoxy) cyclotriphosphazene (HCPCP), is used for the synthesis of a family of fluorescent Ln-HCPCP frameworks (Ln = La, Pr, Nd, Gd, and Ho). Structural analysis shows that the compounds exhibit 3D structures with [Ln3(COO)10], secondary building units formed by Ln-O-C-O-Ln connection. Then the molecules are connected to each other through HCPCP, forming rectangular channels along the c-direction. Interestingly, the fluorescence sensing studies show that compound 1 could be used as a multifunctional fluorescence sensor toward volatile organic compounds via different fluorescence emission behaviors. Moreover, a series of Dye@La-HCPCP composites (Dye = rhodamine B, safranine T, crystal violet, and malachite green) are successfully prepared with different quantum yields by the solvothermal reaction followed by cation exchanges.

Cage Bismuth Metal-Organic Framework Materials Based on a Flexible Triazine-Polycarboxylic Acid: Subgram Synthesis, Application for Sensing, and White Light Tuning.

Bismuth-based metal-organic frameworks (MOFs) have always attracted the attention of many researchers. Here, we first report a crystalline Bi-MOF (Bi-TDPAT) based on a flexible triazine-polycarboxylic linker 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine (H6TDPAT) and bismuth nitrate; its crystallite quality is adequately good and the diffraction data can be collected directly by single crystal X-ray diffraction rather than 3D electron diffraction. The structure of Bi-TDPAT belongs to a novel topology type btt. Notably, the synthesis scale of Bi-TDPAT can be expanded, and sub-gram synthesis can be realized. At the same time, we synthesized a microcrystalline material Bi-TATAB utilizing 2,4,6-tris(4-carboxylphenylamino)-1,3,5-triazine (H3TATAB). The structures of the two materials were characterized by several microanalysis tools. Considering that Bi-TDPAT is a blue light-emitting material with a broad emission peak, we prepared a white light emitting composite material Eu/Tb@Bi-TDPAT by encapsulating Eu(III)/Tb(III) in Bi-TDPAT. In addition, the fluorescence sensing functions of Bi-TDPAT and Bi-TATAB were explored. The results showed that they could detect and recognize various nitrophenols, and the optimal limit of detection is as low as 0.21 µM, which can be reused even after five cycles. Energy competitive absorption (CA) and photo-induced electron transfer are the main sensing mechanisms. By comparing and analyzing the properties of these two bismuth-based crystalline materials, we believe that this work also provides inspiration for the synthesis and development of bismuth-based MOF in the future.

High-Symmetry Co/Ni Triazine Polycarboxylate Diverse Frameworks Constructed by Mx(COO)y Building Blocks: Characterization and Catalytic Performance Evaluation of p-Nitrophenol.

Three new triazine compounds [Co1.5(H3TDPAT)(H2O)3]·6H2O (1), [Co2(TCPT)(µ2-H2O)2]·OH (2), and [Ni3(TCPT)]·3OH (3) were designed and synthesized via the reaction of the symmetrical triazine ligand connected by C-N-C and C-O-C bonds with triazine poly(carboxylic acid)s ligands as the side arms: H6TDPAT (H6TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) and H3TCPT (H3TCPT = 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine) as well as the corresponding metal salts under the solvothermal condition. Three triazine polycarboxylate frameworks were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and solid fluorescent spectra in detail. The structural analysis results showed that the three-dimensional porous cage framework of compound 1 was constructed by three different polyhedral cages connected with [Co(COO)4(H2O)2] building blocks. One of the compounds, 2, is formed by twin propeller Co2(µ2-H2O)(COO)3 building blocks connecting two-dimensional layers and the intermolecular π-π interactions involved the triazine rings between the layers. While the structure of compound 3 is similar to that of 2, assembly is by Ni(COO)3 building blocks and adjacent layers of the face-to-face π-π interaction between the triazine rings. In order to explore functional properties, the catalytic reduction of p-nitrophenol (PNP) of compounds 1-3 was investigated. They exhibit excellent catalytic activity of more than 95% for reduction of PNP with a dose of 2.5 mg of the compounds.

Potential Specificity Between Mycorrhizal Fungi Isolated from Widespread Dendrobium spp. and Rare D. huoshanense Seeds.

In nature, orchid seed germination and seedling development depend on compatible mycorrhizal fungi. Mycorrhizal generalist and specificity affect the orchid distribution and rarity. Here, we investigated the specificity toward fungi in the rare D. huoshanense by mycorrhizal fungal isolation and symbiotic germination in vitro. Twenty mycorrhizal fungal strains were isolated from the roots of adult Dendrobium spp. (six and 12 strains from rare D. huoshanense and widespread D. officinale, respectively, and two strains from D. nobile and D. moniliforme, respectively) and 13 strains belong to Tulasnellaceae and seven strains belong to Serendipitaceae. Germination trials in vitro revealed that all 20 tested fungal strains can stimulate seed germination of D. huoshanense, but only nine strains (~ 50%) can support it up to the seedling stage. This finding indicates that generalistic fungi are important for early germination, but only a few can maintain a symbiosis with host in seedling stage. Thus, a shift of the microbial community from seedling to mature stage probably narrows the D. huoshanense distribution range. In addition, to further understand the relationship between the fungal capability to promote seed germination and fungal enzyme activity, we screened the laccase and pectase activity. The results showed that the two enzymes activities of fungi cannot be directly correlated with their germination-promoting activities. Understanding the host specificity degree toward fungi can help to better interpret the limited geographic distribution of D. huoshanense and provides opportunities for in situ and ex situ conservation and reintroduction programs.

Spin-Orbit Charge-Transfer Intersystem Crossing in Anthracene-Perylenebisimide Compact Electron Donor-Acceptor Dyads and Triads and Photochemical Dianion Formation.

Perylenebisimide (PBI)-anthracene (AN) donor-acceptor dyads/triad were prepared to investigate spin-orbit charge-transfer intersystem crossing (SOCT-ISC). Molecular conformation was controlled by connecting PBI units to the 2- or 9-position of the AN moiety. Steady-state, time-resolved transient absorption and emission spectroscopy revealed that chromophore orientation, electronic coupling, and dihedral angle between donor and acceptor exert a significant effect on the photophysical property. The dyad PBI-9-AN with orthogonal geometry shows weak ground-state coupling and efficient intersystem crossing (ISC, ΦΔ =86 %) as compared with PBI-2-AN (ΦΔ =57 %), which has a more coplanar geometry. By nanosecond transient absorption spectroscopy, a long-lived PBI localized triplet state was observed (τT =139 µs). Time-resolved EPR spectroscopy demonstrated that the electron spin polarization pattern of the triplet state is sensitive to the geometry and number of AN units attached to PBI. Reversible and stepwise generation of near-IR-absorbing PBI radical anion (PBI-⋅ ) and dianion (PBI2- ) was observed on photoexcitation in the presence of triethanolamine, and it was confirmed that selective photoexcitation at the near-IR absorption bands of PBI.- is unable to produce PBI2- .

Integrated Photoresponsive Alkaline Earth Metal Coordination Networks: Synthesis, Topology, Photochromism and Photoluminescence Investigation.

Photoresponsive materials are a key part of the age of smart technology that have potential in a broad range of applications. Coordination networks (CNs) are widely used due to their designability and stability. In this work, three novel alkaline earth metal coordination networks (AEM-CNs): [Mg(CMNDI)(H2 O)2 ], [Ca(CMNDI)(H2 O)2 ]⋅H2 O, and [Sr(CMNDI)(H2 O)(DMF)] with fsl, cds, and scn topology nets were synthetized via N,N'-bis(carboxymethyl)-1,4,5,8-naphthalenediimide (H2 CMNDI); the scn net is not found in the Reticular Chemistry Structure Resource or ToposPro. The reusable and sensitive photochromic properties of the three CNs enable them to be used as secret inks or ultraviolet detectors. In addition, the CNs also exhibited reusable photoluminescent turn-off toward the drug molecules, balsalazide disodium (Bal.) and colchicine (Col.), with good limits of detection of 0.16 and 0.70 µM. To the best of our knowledge, this is the first study of a fluorescence sensor for Bal. Thus, the AEM-CNs provide a design idea for integrated photoresponsive materials that could be further improved in the near future by further study.

Cu-MOF Material Constructed with a Triazine Polycarboxylate Skeleton: Multifunctional Identify and Microdetecting of the Aromatic Diamine Family (o,m,p-Phenylenediamine) Based on the Luminescent Response.

Organic aromatic amines are widely used in various fields such as pharmaceuticals, pesticides, dyes, and tobacco smoke. The pollution of organic amines has become a problem that cannot be ignored, due to the extensive harmful effects on the environment and public health, which has become one of the most concerned frontier fields in the world. Identifying and microdetecting o-phenylenediamine (OPD), m-phenylenediamine (MPD), and p-phenylenediamine (PPD) using MOFs have rarely been reported. On the basis of the blue emission properties of Cu-TBDA constructed with 5,5'-((6-chloro-1,3,5-triazine-2,4-diyl)bis(azanediyl))diisophthalic acid (H4TBDA) ligand, Cu-TBDA was studied primarily to identify and detect aromatic diamine family as a multifunctional chemical sensor. Interestingly, Cu-TBDA has a very high selectivity and sensitivity to OPD and MPD with a low limit of detection (5.00 µM for OPD and 1.77 µM for MPD). Especially for OPD, Cu-TBDA has a unique switching function for it. When the concentration of OPD is less than 9.1 × 10-4 M, the fluorescence response of Cu-TBDA suspension exhibit enhanced. However, when the concentration of OPD is more than 9.1 × 10-4 M, the emission intensity displays quenching phenomenon. Therefore, Cu-TBDA as a chemical sensor not only has recognition and detection functions for organic aromatic amines but also first exhibits turn-on and -off sensing behavior toward OPD.

Three Pbx(COO)y Cluster Frameworks Based on a Flexible Triazinetricarboxylic Acid Ligand: Syntheses, Structures, and Fluorescent Sensing Application for Nitrophenols.

Three new metal-organic frameworks (MOFs), namely, [Pb7(TTPCA)4Cl2]·3H2O (1), [Pb7(TTPCA)4(DMA)2(HCOO)2]·H2O (2), and [Pb4(TTPCA)3]·3DMF·2H2O·H3O (3), were synthesized by the H3TTPCA ligand [H3TTPCA = 1,1',1″-(1,3,5-triazine-2,4,6-triyl)-tripiperidine-4-carboxylic acid], with lead(II) nitrate under solvothermal conditions. They were characterized by CHN analysis, IR spectroscopy, UV-vis spectroscopy, and single-crystal and powder X-ray diffraction. In addition, their thermogravimetric analysis and fluorescence properties were studied. Compounds 1-3 were 3D MOF structures with different Pbx(COO)y clusters: ([Pb7(COO)12Cl2]), ([Pb7(COO)12]), and [Pb8(COO)18]. Fluorescence detection of compounds 1-3 shows that they can act as excellent sensors of nitrophenols with a low limit of detection and a high quenching constant.