Two Novel Cu/Mn Metal-Organic Framework Based on Aromatic Dicarboxylic Acid: Synthesis, Crystal Structure, Thermal Stability, and Luminescence Properties

<p>Two novel transition metal complexes formulated as [Cu(4,5-Himdc)(phen)]<i>_n</i> (<b>1</b>) and [Mn(5,6-Hbidc)(H₂O)]<i>_n</i> (<b>2</b>) (4,5-H₃imdc = imidazole-4,5-dicarboxylic acid, 5,6-H₃bidc = 1<i>H</i>-benzimidazole-5,6-dicarboxylic acid, phen = 1,10-phenanthroline) have been synthesized under hydro(solvo)thermal method at a relatively low temperature and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. <b>1</b> based on 4,5-H₃imdc displays one-dimensional zigzag chain structure. <b>2</b> based on 5,6-H₃bidc features a two-dimensional framework with 4-connected topology. Thermal stabilities and luminescence properties of the two complexes were investigated.</p

Hot-Pressing Method To Prepare Imidazole-Based Zn(II) Metal–Organic Complexes Coatings for Highly Efficient Air Filtration

Particulate matters (PMs) air pollution has become a serious environmental issue due to its great threat to human health. Herein, metal–organic complexes PBM-Zn1 and PBM-Zn2 coatings (noted as PBM-Zn-Filter) have been produced by the hot-pressing method on various substrates for the first time. Layer-by-layer PBM-Zn-Filters were also obtained through varying hot-pressing cycles. The obtained PBM-Zn-Filters with high robustness show excellent performance in PMs removal. In particular, benefiting from thelarger conjugation system, micropore structure, lower pressure drop, higher electrostatic potential ζ, and electron cloud exposed metal center of PBM-Zn2 (DFT calculations), PBM-Zn2@melamine foam-4 gives the highest removal rates, PM2.5:99.5% ± 1.2% and PM10:99.3% ± 1.1%, and the removal efficiency for capture PM2.5 and PM10 particles in cigarette smoke were both retained at high levels (>95.5%) after 24 h tests. More importantly, a homemade mask is made up by imbedding the PBM-Zn2@melamine foam-4 into a commercial breathing mask, which shows higher removal efficiency, lower pressure drop, smaller thickness, and higher quality factor than two commercial breathing masks, the PMs removal efficiencies for both PM2.5 and PM10 are 99.6% ± 0.5% and 99.4% ± 0.8%, and acceptable air resistance are demonstrated

Keggin-Type PMo₁₁V as a P‑type Dopant for Enhancing the Efficiency and Reproducibility of Perovskite Solar Cells

The conventional perovskite solar cells (PSCs) with 2,2′,7,7′-tetrakis­(<i>N</i>,<i>N</i>-dimethoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) as a hole transporting material commonly suffer from poor stability and reproducibility mainly due to the process of placing the devices in air and illumination for oxidizing the spiro-OMeTAD. Herein, Keggin-type polyoxometalates (POMs)-phosphovanadomolybdate (H₄PMo₁₁V·nH₂O, denoted as PMo₁₁V) is for the first time employed as a p-type dopant for promoting the oxidation of spiro-OMeTAD. Thereby, without illumination and air, the conductivity and hole extraction efficiency of the PMo₁₁V doped spiro-OMeTAD with assistance of lithium bis­(trifluoromethanesulfonyl)­imide (Li-TFSI) and 4-<i>tert</i>-butylpyridine (TBP) can be dramatically enhanced. On the basis of this strategy, the corresponding PSCs exhibit substantially improved photovoltaic performance and good reproducibility. The best performing device yields a power conversion efficiency (PCE) of 14.05%. This work indicates a great potential of polyoxometalates for further applications in solar cells and other optoelectronics devices

Conductive Upconversion Er,Yb-FTO Nanoparticle Coating To Replace Pt as a Low-Cost and High-Performance Counter Electrode for Dye-Sensitized Solar Cells

F-doped SnO₂ (FTO) nanocrystals modified by Er and Yb with upconversion capability and excellent catalytic properties have been designed and fabricated as an economic replacement for Pt for use as the counter electrode (CE) in dye-sensitized solar cells. The cost of the UC-FTO counter electrode is only ∼¹/₂₀th of that for Pt. The upconverted luminescence-mediated energy transfer and the superior catalytic property for I₃^–/I^– circulation overpowered the slight degradation caused by increased CE/electrolyte interface resistance. A 23.9% enhancement in photocurrent was achieved with little degradation in photovoltage, resulting in a 9.12% increase in solar-to-electric power conversion efficiency. Near-infrared (NIR) light-to-electricity has been directly observed by SPS and IPCE characterizations, showing the effect of the upconversion counter electrode

3D Lanthanide Metal–Organic Frameworks Based on Mono‑, Tri‑, and Heterometallic Tetranuclear Clusters as Highly Selective and Sensitive Luminescent Sensor for Fe³⁺ and Cu²⁺ Ions

Five novel three-dimensional lanthanide metal–organic frameworks (Ln–MOFs) constructed by 4-(3′,5′-dicarboxylphenoxy) phthalic acid (H₄dcppa), namely, {[Eu­(Hdcppa)­(H₂O)₂]·H₂O}_<i>n</i> (<b>Eu-1</b>), [Eu_1.5(dcppa) (HCOO)_0.5(H₂O)₂]_<i>n</i> (<b>Eu-2</b>), {[Ln₂K₂(dcppa)₂(H₂O)₆]·<i>m</i>H₂O}_<i>n</i> (Ln = <b>Eu-3</b>, <b>Tb-4</b>, <b>Gd-5</b>, <i>m</i> = 5 for <b>Eu-3</b> and <b>Tb-4</b>; <i>m</i> = 4 for <b>Gd-5</b>) (HCOOH = formic acid) have been prepared by hydro­(solvo)­thermal method and fully characterized. Structural analyses indicated that H₄dcppa ligand took four different coordination fashions in <b>1</b>–<b>5</b> and, thus, resulted in diversity of the targeted Ln–MOFs: <b>Eu-1</b> displays the rare 3D (5,5)-connected <b>vbk</b> net, containing one-dimensional left- and right-handed helical chains; <b>Eu-2</b> possesses a 3D (3,8)-connected <b>tfz-d</b> topology constructed by trinuclear paddlewheel [Eu₃(CO₂)₆] SBUs; <b>3</b>–<b>5</b> are isostructural and show 3D (Ln-dcppa^4–) + 2D (K-dcppa^4–) → 3D (LnK-dcppa^4–) structure. <b>Eu-3</b>, with regular 1D channels and open Lewis basic oxygen atoms on the pore surface was utilized for specific sensing and binding of metal ions through Lewis base interactions, shows high selectivity, fast response time (8 min), and high sensitivity (<i>K</i>_SV = 4.3/5.2 × 10⁴ L/mol) for Fe³⁺ and Cu²⁺ ions with luminescent quenching. Furthermore, the detection limit of the sensor is in the 10^–6 M level. The triplet state (T₁ = 23364 cm^–1) of H₄dcppa studied by the Gd­(III)–MOF and <b>Gd-5</b> demonstrates that the ligand ideally populates Eu­(III)/Tb­(III) emission with luminescent quantum yields (Φ_overall) of 11.2% for <b>Eu-1</b>, 27.6% for <b>Eu-2</b>, 18.5% for <b>Eu-3</b>, and 62% for <b>Tb-4</b>, respectively

Unusually Flexible Indium(III) Metal–Organic Polyhedra Materials for Detecting Trace Amounts of Water in Organic Solvents and High Proton Conductivity

Humidity-induced single-crystal transformation was observed in the indium metal–organic polyhedra [In₂(TCPB)₂]·2H₂O (<b>In1</b>), where H₃TCPB is 1,3,5-tri­(4-carboxyphenoxy)­benzene. When the humidity is above 58% relative humidity (RH) at room temperature, the neutral compound <b>In1</b> could be successfully converted into the positively charged compound <b>In1</b>-<b>H</b> along with the color change from yellow to deep red, which also undergoes a reversible transformation into <b>In1</b> driven by thermal dehydration. Notably, the color of <b>In1</b> takes only 5 min to change under 58% RH at room temperature, which is much quicker than common desiccant bluestone. As the water content is increased from 0.0% to 0.2% in acetonitrile solvent, compound <b>In1</b> exhibits rapid detection of trace amounts of water through turn-off luminescence sensing mechanism with a low detection limit of 2.95 × 10^–4%. Because of the formation of extensive hydrogen-bonding network between the metal–organic polyhedra (MOPs) and surrounding guest OH^– ions, compound <b>In1</b>-<b>H</b>, along with isostructural <b>Ga1</b>-<b>H</b>, displays excellent proton conductivity up to 2.84 × 10^–4 and 2.26 × 10^–4 S cm^–1 at 298 K and 98% RH, respectively. Furthermore, the activation energies are found to be 0.28 eV for <b>In1</b>-<b>H</b> and 0.34 eV for <b>Ga1</b>-<b>H</b>. This method of incorporation of OH^– ions to obtain high proton conductivity MOPs with low activation energy demonstrates the advantage of OH^– ion conduction in the solid-state materials

Cooperative Crystallization of Chiral Heterometallic Indium(III)–Potassium(I) Metal–Organic Frameworks as Photosensitizers in Luminescence Sensors and Dye-Sensitized Solar Cells

In this work, the coexistence of In­(III) and K­(I) induces a rapid crystal growth of single crystals of heterometallic metal–organic frameworks (MOFs), [In_0.5K­(3-qlc)­Cl_1.5(H₂O)_0.5]_2<i>n</i> (<b>1</b>) and [InK­(ox)₂­(H₂O)₄]_<i>n</i> (<b>2</b>) (3-Hqlc = quinoline-3-carboxylic acid; H₂ox = oxalic acid). Remarkably, with the help of achiral 3-Hqlc, compound <b>1</b> represents the chiral interpenetrating p-block heterometallic MOFs with helical chain along the 4₃ screw axis, while compound <b>2</b> possesses a highly symmetric (4,4,4)-connected topology network with a Schläfli symbol of (4²·8³·10)­(4²·8⁴). Consideration of two different organic ligands viz. 3-Hqlc and H₂ox constructed heterometallic MOFs with different geometrical dimensions of unit cells, their influences on luminescence and photovoltaic properties are studied. Compounds <b>1</b> and <b>2</b> show tunable luminescence from blue to yellow and white by varying the temperature in the solid state. Encouraged by the UV–visible absorption and HOMO–LUMO energy states matched for sensitizing TiO₂, the two compounds are employed in combination with N719 in dye-sensitized solar cells (DSSCs) to compensate for absorption in the region of ultraviolet and blue-violet. Under optimized conditions, the DSSCs devices using cosensitizers of <b>1</b>/N719 and <b>2</b>/N719 display an overall conversion efficiency of 8.07% and 7.42%, which is 22.09% and 12.25% higher than that of a device solely sensitized by N719 (6.61%). Consequently, both of the two compounds could serve as excellent photosensitizers and application in luminescence sensors and DSSCs

Dual-Stimulus-Triggered Programmable Drug Release and Luminescent Ratiometric pH Sensing from Chemically Stable Biocompatible Zinc Metal–Organic Framework

Metal–organic frameworks (MOFs), as drug delivery carriers, with high loading capacity and controllable release behavior can provide a more efficacious therapy in cancer treatments. In our work, a novel biocompatible zinc MOF <b>Zn-cpon-1</b> with the (3,6)-connected <i>rtl</i> 3D topological network was designed and synthesized via employing ClO₄^– anion as template. The optically and chemically stable <b>Zn-cpon-1</b> could be verified as a pH-responsive dual-emission platform and excellent drug delivery carrier with higher 5-fluorouracil (5-FU) (44.75 wt %) loading behavior than 6-mercaptopurine (6-MP) (4.79 wt %) ascribed to the influence of size and shape matching. The multiple interactions between <b>Zn-cpon-1</b> and 5-FU drug molecules have been discussed and evidenced, which could be quantitatively estimated via the rate constant related to the topological structure. Specially, the gust release behavior of 5-FU@<b>Zn-cpon-1</b> microcrystal was described and programmed via the Weibull distribution model and could be dual-triggered by the temperature and pH stimulus. This study illustrates that the <b>Zn-cpon-1</b> without any postmodification performs a favorable potential of being used as biomedical drug delivery alternative carriers in effective drug payload, flexible release administration, and superior dual-stimuli responsiveness

Dual-Stimulus-Triggered Programmable Drug Release and Luminescent Ratiometric pH Sensing from Chemically Stable Biocompatible Zinc Metal–Organic Framework

Metal–organic frameworks (MOFs), as drug delivery carriers, with high loading capacity and controllable release behavior can provide a more efficacious therapy in cancer treatments. In our work, a novel biocompatible zinc MOF <b>Zn-cpon-1</b> with the (3,6)-connected <i>rtl</i> 3D topological network was designed and synthesized via employing ClO₄^– anion as template. The optically and chemically stable <b>Zn-cpon-1</b> could be verified as a pH-responsive dual-emission platform and excellent drug delivery carrier with higher 5-fluorouracil (5-FU) (44.75 wt %) loading behavior than 6-mercaptopurine (6-MP) (4.79 wt %) ascribed to the influence of size and shape matching. The multiple interactions between <b>Zn-cpon-1</b> and 5-FU drug molecules have been discussed and evidenced, which could be quantitatively estimated via the rate constant related to the topological structure. Specially, the gust release behavior of 5-FU@<b>Zn-cpon-1</b> microcrystal was described and programmed via the Weibull distribution model and could be dual-triggered by the temperature and pH stimulus. This study illustrates that the <b>Zn-cpon-1</b> without any postmodification performs a favorable potential of being used as biomedical drug delivery alternative carriers in effective drug payload, flexible release administration, and superior dual-stimuli responsiveness

Unusually Flexible Indium(III) Metal–Organic Polyhedra Materials for Detecting Trace Amounts of Water in Organic Solvents and High Proton Conductivity

Humidity-induced single-crystal transformation was observed in the indium metal–organic polyhedra [In₂(TCPB)₂]·2H₂O (<b>In1</b>), where H₃TCPB is 1,3,5-tri­(4-carboxyphenoxy)­benzene. When the humidity is above 58% relative humidity (RH) at room temperature, the neutral compound <b>In1</b> could be successfully converted into the positively charged compound <b>In1</b>-<b>H</b> along with the color change from yellow to deep red, which also undergoes a reversible transformation into <b>In1</b> driven by thermal dehydration. Notably, the color of <b>In1</b> takes only 5 min to change under 58% RH at room temperature, which is much quicker than common desiccant bluestone. As the water content is increased from 0.0% to 0.2% in acetonitrile solvent, compound <b>In1</b> exhibits rapid detection of trace amounts of water through turn-off luminescence sensing mechanism with a low detection limit of 2.95 × 10^–4%. Because of the formation of extensive hydrogen-bonding network between the metal–organic polyhedra (MOPs) and surrounding guest OH^– ions, compound <b>In1</b>-<b>H</b>, along with isostructural <b>Ga1</b>-<b>H</b>, displays excellent proton conductivity up to 2.84 × 10^–4 and 2.26 × 10^–4 S cm^–1 at 298 K and 98% RH, respectively. Furthermore, the activation energies are found to be 0.28 eV for <b>In1</b>-<b>H</b> and 0.34 eV for <b>Ga1</b>-<b>H</b>. This method of incorporation of OH^– ions to obtain high proton conductivity MOPs with low activation energy demonstrates the advantage of OH^– ion conduction in the solid-state materials