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BackgroundCurrently, insufficient bone volume always occurs in the posterior maxilla which makes implantation difficult. Short implants combined with transcrestal sinus floor elevation (TSFE) may be an option to address insufficient bone volume.PurposeThe clinical performance of short implants combined with TSFE was compared with that of conventional implants combined with TSFE according to the survival rate.MethodIn this systematic review and meta-analysis, we followed the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Articles were identified through PubMed, Embase, the Cochrane Library, and manual searching. Eligibility criteria included clinical human studies. The quality assessment was performed according to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines. The odds ratio (OR) with its confidence interval (CI) was considered the essential outcome for estimating the effect of short implants combined with TSFE.ResultsThe registration number is INPLASY202050092. Eleven studies met the inclusion criteria, including 1 cohort study and 10 cross-sectional studies. With respect to the 1-year survival rate, no significant effect was observed between short implants (length ≤ 8 mm) and conventional implants combined with TSFE (I2=0%, OR=1.04, 95% CI: 0.55-1.96). Similarly, no difference was seen between the two groups regarding the survival rate during the healing period (I2=10%, OR=0.74, 95% CI: 0.28-1.97) and 3-year loading (OR=1.76, 95% CI: 0.65-4.74).ConclusionThere was no evidence that the survival rate of short implants combined with TSFE was lower or higher than that of conventional implants combined with TSFE when the residual bone height was poor and the implant protrusion length of short implants was less than or similar to conventional implants. Nevertheless, the results should be interpreted cautiously due to the lack of random controlled trials in our meta-analysis.

Searching for high-efficient, good long-term stability, and low-cost electrocatalysts toward oxygen reduction reaction (ORR) is highly desirable for the development of sustainable energy conversion devices. Iron–nitrogen doped carbon (Fe–N/C) catalysts have been recognized as the most promising candidates for traditional Pt-based catalysts that benefit from their high activity, excellent anti-poisoning ability, and inexpensiveness. Here, a super-dispersed and high-performance Fe–N/C catalyst was derived from chemically Fe-doped zeolitic imidazolate frameworks (ZIFs) by directly bonding Fe ions to imidazolate ligands within 3D frameworks. It produced a series of catalysts, whose sizes could be tuned in the range from 62 to over 473 nm in diameter. After rationally regulating the component and heating treatment, the best ORR activity was measured for the catalyst with a size of 105 nm, which was obtained when the Fe3+/Zn2+ molar ratio was 0.05 and carbonization temperature was 900 °C. It exhibited a high onset potential (Eonset = 0.99 V) and half-wave potential (E1/2 = 0.885 V) compared with a commercial 20% Pt/C catalyst (Eonset = 0.10 V, E1/2 = 0.861 V) as well as much better durability and methanol resistance in an alkaline electrolyte.

The first mixed-valence nickel-supported polyoxometalate-based metal–organic framework, (H2mim)[NiIII(Hmim)4][SiW11NiIIO37(OH)2(Hmim)]·3H2O (1) (Hmim = 2-methylimidazole), has been synthesized using a steam-assisted conversion method, and is constructed from noncovalent interactions (hydrogen bonds and π⋯π stacking interactions). 1 has a repeating honeycomb-shaped internal structure with one-dimensional channels along the direction of the c axis, where the diameter of the aperture is as large as 18.83 A. Furthermore, the stability and the optical band gaps are investigated.

A new three-dimensional metal–organic framework constructed form pentanuclear tetrahedral cluster and linear dicarboxylic acid ligand, [Zn5(btz)6(ndc)2(H2O)]·3DMA (1) (btz = benzotriazole, H2ndc = 1,4-naphthalenedicarboxylic acid) has been synthesized by the modular building blocks (MBBs) strategy under the solvothermal condition. Single X-ray diffraction reveals that 1 is a two-fold interpenetrated framework with mdf topology, in which pentanuclear {Zn5(btz)6} cluster acts as a 4-connected node. Moreover, the luminescent properties of 1 dispersed in different metal ions and solvents have been investigated systematically.

Four novel high-dimensional metal–organic rotaxane frameworks (MORFs) were successfully fabricated by cucurbit[6]uril-based pseudorotaxanes ([PR43]) and rigid carboxylate ligands by adjusting the synthesis temperature and the length of ligands. Compound 1 represents a three periodic 2-fold interpenetrating dia network based on a binuclear {Cd2Cl4O4} second building unit (SBU). 2 and 3 are isostructural pcu networks constructed by binuclear and trinuclear cadmium clusters, respectively, while compound 4 is a two-dimensional layered network with a large grid 44.3 × 19.8 A2. Furthermore, their fluorescent properties in different solvents are investigated.

A series of organic–inorganic hybrid compounds built from Keggin and Wells–Dawson polyoxometalates and TM-trz complexes (Htrz = 1,2,4-triazole) were obtained at different pH values under hydrothermal conditions, namely, [Co2(H2O)2(Htrz)5][SiW12O40]·2.5H2O (1), [Zn5(Htrz)8(trz)2(H2O)8][SiW12O40]2·10H2O (2), [CuI2CuII4(Htrz)4(trz)4Cl2][GeW12O40]·15H2O (3), [CuI2CuII4(Htrz)4(trz)4Cl2][SiW12O40]·15H2O (4), K2Na2(H2O)2[Co11(trz)14(H2O)14][P2W18O62]2·29H2O (5) and [Cu12(trz)10(Htrz)2(OH)4(SO4)2(H2O)6][P2W18O62]·28H2O (6). All of the compounds were characterized using single-crystal X-ray diffraction, TG analysis and powder X-ray diffraction. Compound 1 contains a kind of bimetallic–organic segment [Co2(Htrz)5]4+, which could be regarded as a quasi-sinusoid-like chain. 2 is a dimer constructed from two [SiW12O40]4− units linked by a [Zn5(trz)2(Htrz)8]8+ motif. In 3 and 4, the 2D wall-like layers constructed by the Cu(II) ions and Htrz ligands are extended into 3D frameworks by polyanions. 5 shows a complicated three-dimensional (3D) framework with a {412·612·84}{46}2 topology. Compound 6 is also a complicated 3D structure based on a triangular trinuclear Cu-trz unit and [P2W18O62] polyanions. To the best of our knowledge, 6 represents the largest copper cluster linked by amines in a POM system. Structural diversities reveal that the pH value of the reaction system plays a crucial role in the assembly of POM-based hybrids. Moreover, the optical band gaps, electrochemical properties, magnetic properties and the photocatalytic properties of the compounds have been investigated.

A versatile one-pot strategy was employed to synthesize five cerium(III)-containing polyoxotungstate nanoclusters through pH-controlled and sulfite anion-directed assembly: [C2H8N]3Na7[Ce2(H2O)6W22O72(OH)4]·20H2O (1) at pH 5.0; [C2H8N]8Na16[Ce4(H2O)12W44O144(OH)12]·23H2O (2) at pH 4.5; [C2H8N]2Na4Ce2[Ce2(H2O)10W28O92(OH)2]·27H2O (3) at pH 2.8-3.3; [C2H8N]2Na7[{α-SW7O28}{Ce2(H2O)6}(W3O6){α-SW9O32}{α-SW9O31(OH)}]·18H2O (4) at pH 2.5; [C2H8N]2Na18[Ce2(H2O)9W36O110(OH)12]2·30H2O (5) at pH 1.5. These compounds were characterized by single-crystal X-ray structure analysis, IR spectroscopy, thermogravimetric (TG) analysis, X-ray photoelectron spectroscopy (XPS), and electrospray ionization mass spectrometry (ESI-MS). Moreover, their electrochemical properties were investigated. Single-crystal X-ray structure analysis revealed that 1 and 2 were di- and tetra-cerium(III)-bridged polyoxotungstates, constructed from two different types of lacunary {W11} units. 3 composed of the well-known cerium(III)-stabilized {W28} unit and organic amine-sodium-cerium cations, was isolated in the pH range 2.8-3.3. In this reaction system, the SO3(2-) anion acted as a heteroanion template at a lower pH 2.5. 4 was isolated by the combination of cerium(III) centers and SO3(2-) heteroanion template, which is the first lanthanide-containing polyoxotungstates with sulfur heteroatoms, and the 4f metal cerium(III) centers in 4 both have eight-coordinated modes and the SO3(2-) heteroanion templates display μ7 and μ9 coordination modes. At a much lower pH 1.5, the polyanion of 5 was obtained, two triangular-shaped {W36} subunits were bridged by the cerium(III) ions, resulting in the largest lanthanide-containing iso-polyoxotungstates known to date.

The first macrocycle-based high-nuclearity nanocluster [Ag(20)(S(t)Bu)(10)(CF(3)COO)(2)](8+) in complex 1, with a sandwich-like structure constructed by bilevel inversion Ag(5)S(5) pentagrams and an interlayer Ag(10) ring, has been obtained. Structure analysis indicates that Cl(-) acts as an anion template to direct the formation of 1. In addition, the photoluminescent property of complex 1 is also investigated.

A new inorganic–organic hybrid compound constructed from Keggin-type polyoxometalate and cadmium-organic units, namely, [Cd(Htrz)3]2[SiW12O40]·2H2O (1), [Htrz = 1-H-1,2,4-triazole], has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, TG, and UV–vis absorption spectra. In compound 1, each [SiW12O40]4 − cluster is modified by six [Cd(Htrz)3]2 + metal–organic fragments, meanwhile, each [Cd(Htrz)3]2 + also connects with three [SiW12O40]4 − to built up a binodal (3,6)-connected 2D planar network with the (43)2(46·66·83)-kgd topology. Interestingly, [SiW12O40]4 − cluster exhibits a rare coordination mode acting as a hexadentate ligand, in which all of the six terminal oxygen atoms in the equatorial plane are synchronously participated in coordination. The diffuse reflectivity spectrum shows it can be regarded as a wide gap semiconductor. Moreover, the photocatalytic performance shows good photocatalytic activity for the degradation of Rhodamine B.

Two Fe-substituted Dawson-type nanoscale selenotungstate clusters, {Fe6Se6W34} and {Fe10Se8W62} involving {α-Se2W14} and {γ-Se2W14} building blocks, have been isolated, which exhibit photocatalytic H2 evolution activity. Their electrochemical behaviours and magnetic properties were also investigated.

The first polyoxometalate-based metal–organic nanotube constructed via covalent bonds has been synthesized. POM anions stick the metal–organic nanotubes to build 3D nanotubular arrays. The stability, magnetic and proton conducting properties are investigated.

The cerium(III)-containing polyoxotungstates (III)—(VII) are characterized by single crystal XRD, IR spectroscopy, XPS, ESI-MS, and electrochemical measurements.

Compounds (IV) and (VII) crystallize in the triclinic space group P with Z = 1 (single crystal XRD).

A novel δ-Dawson [(WO5)3W14Mn2(III)O44Cl2](12-) compound induced by the Jahn-Teller distortion of Mn(III) has been synthesized through utilizing {Mn12} as a reactant, which exhibits photocatalytic H2 evolution activity. Its electrochemical behavior and magnetic properties were investigated.

Three novel self-catenated 4-connected uninodal (6(5)·8)- metal-organic rotaxane frameworks (MORFs) containing cucurbit[6]uril were constructed from the in situ trans/cis-configuration (1 : 1) of rotaxanes by taking advantage of a d(10) metal ion directed synthesis. It was revealed that the effect of hydrogen bonds and π-π stacking interactions play significant roles in the self-assembly process.

Three cobalt(II)-containing tungstophosphate compounds, Na8Li8Co5[Co5.5(H2O)19P8W48.5O184]⋅60 H2O (1), K2Na4Li11Co5[Co7(H2O)28P8W48O184]Cl⋅ 59 H2O (2), and K2Na4LiCo11[Co8(H2O)32P8W48O184](CH3COO)4Cl⋅47 H2O (3), have been synthesized and characterized by IR spectroscopy, thermogravimetric analysis, elemental analyses, and magnetic measurements. The pH value impacts the formation of distinct cobalt-linked frameworks. The cyclic cavity of the polyanion accommodates 5.5, 7, and 8 cobalt ions in 1, 2, and 3, respectively. In compounds 1 and 2, each {Co5.5P8W48} and {Co7P8W48} fragment links to four others through multiple {Co-O-W} coordination bonds to generate a two-dimensional network. Compound 3 can be considered as a 3D network based on the {Co-O-W} coordination bonds and the {Co3(CH3COO)2(H2O)10} linkers between the {P8W48} fragments. Interestingly, acetate ligands have been employed to form the {Co3(CH3COO)2(H2O)10} unit, thereby inducing the construction of a 12-connected framework. To the best of our knowledge, compound 3 contains the largest-ever number of cobalt ions in a {P8W48}-based polyoxometalate when counterions are taken into account and the {P8W48} unit shows the highest number of connections thanks to the carboxyl bridges. The UV/Vis diffuse reflectance spectra of these powder samples indicate that the corresponding well-defined optical absorption associated with Eg can be assessed at 2.58, 2.48, and 2.73 eV and reveal the presence of an optical band gap. The photocatalytic H2 evolution activities of these {P8W48}-based compounds are evaluated.

The new compound {[Cu6(phen)6(H2O)3] [Nb10V4O40(OH)2]}2 ·13H2O is obtained from an aqueous mixture of K7HNb6O19, Cu(OAc)2, NaVO3, phen, and NaOH (pH 11.2, 58 °C, 8 h, 57% yield).

An unprecedented organic-inorganic hybrid {[Cu(6)L(6)(H(2)O)(3)][Nb(10)V(4)O(40)(OH)(2)]}(2)·13H(2)O (1) (L = 1,10-phenanthroline) containing the unreported {Nb(10)V(4)O(40)(OH)(2)}(12-) building blocks has been successfully synthesized and its photoluminescent properties, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction were investigated.