Effects of Halogen Bonding in Chemical Activity of Lead(II) Electron Pair: Sonochemical Synthesis,Structural Studies,and Thermal Analysis of Novel Lead(II) Nano Coordination Polymer

The nanoflower lead(II) coordination compound {[Pb(phen)(μ‐CH₃COO)][PF₆]}_n ( 1 ) (phen = 1,10‐phenanthroline) was synthesized by a sonochemical method. The nanostructure was characterized by using scanning electron microscopy (SEM), X‐ray powder diffraction, elemental analysis, and thermal analysis. The single‐crystal X‐ray structure shows that the overall structure of 1 is a 1D coordination polymer. Complex 1 has a bridging acetate pathway. Three halogen bonds observed in the structure and the strong halogen bonding of F–Pb causes chemical activity of the lead electron pair. This is further extended into a 3D supramolecular structure by weak π–π intermolecular interactions. The coordination number of the lead(II) ions is six, resulting in PbN₂O₄. PbO nanoparticles were obtained by the thermolysis of 1 at 180 °C with oleic acid as a surfactant. The morphology and size of the prepared PbO nanoparticles were further observed using scanning electron (SEM) and transmission electron microscopy (TEM), and were analyzed by X‐ray photoelectron spectroscopy (XPS).     

Sonochemical Synthesis of a Novel Nanoscale Lead(II) Coordination Polymer: Synthesis,Crystal Structure,Thermal Properties,and DFT Calculations of [Pb(dmp)(μ‐N3)(μ‐NO3)]n with the Novel Pb2(μ‐N3)2(μ‐NO3)2 Unit

A new nanostructured coordination polymer of divalent lead with the ligand 2,9‐dimethyl‐1,10‐phenanthroline (dmp), [Pb(dmp)(μ‐N₃)(μ‐NO₃)]_n ( 1 ), was synthesized by sonochemical methods. The polymer was characterized by scanning electron microscopy, X‐ray powder diffraction, IR, ¹H NMR, and ¹³C NMR spectroscopy, and elemental analyses. Compound 1 was structurally characterized by single‐crystal X‐ray diffraction. The single‐crystal analysis shows that the coordination number of Pb^II ions is seven, (PbN₄O₃) has a “stereo‐chemically active” electron lone pair, and the coordination sphere is hemidirected. The chains interact with each other through π–π stacking interactions to create a 3D framework. The structure of the title complex was optimized by density functional calculations. The calculated structural parameters and the IR spectrum of the title complex are in agreement with the crystal structure.     

A Novel Polymeric Lead(II)‐Azido Compound: Synthesis,Structural Characterization,and DFT Calculations of [Pb(dmp)(N3)2]n

A novel 1D Pb^II coordination polymer containing Pb₂‐(μ‐N₃)₂ unit [Pb(dmp)(N₃)₂]_n (dmp =  2,9‐dimethyl‐1,10‐phenanthroline) has been prepared and characterized. Single‐crystal X‐ray diffraction analyses show that the coordination number for Pb^II ions is six, PbN₆, with “stereochemically active” electron lone pairs and the coordination sphere being hemidirected. The single‐crystal X‐ray data show the chains interact with each other through the π–π stacking interactions, which create a 3D framework. The structure of title complex has been optimized by density functional theory. Structural parameters and IR spectra for the complex are in agreement with the crystal structure.     

Pt‐Pd‐Co Trimetallic Alloy Network Nanostructures with Superior Electrocatalytic Activity towards the Oxygen Reduction Reaction

Pt alloy nanostructures show great promise as electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes. Herein, three‐dimensional (3D) Pt‐Pd‐Co trimetallic network nanostructures (TNNs) with a high degree of alloying are synthesized through a room temperature wet chemical synthetic method by using K₂PtCl₄/K₃Co(CN)₆–K₂PdCl₄/K₃Co(CN)₆ mixed cyanogels as the reaction precursor in the absence of surfactants and templates. The size, morphology, and surface composition of the Pt‐Pd‐Co TNNs are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected‐area electron diffraction (SAED), energy dispersive spectroscopy (EDS), EDS mapping, X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). The 3D backbone structure, solid nature, and trimetallic properties of the mixed cyanogels are responsible for the 3D structure and high degree of alloying of the as‐prepared products. Compared with commercially available Pt black, the Pt‐Pd‐Co TNNs exhibit superior electrocatalytic activity and stability towards the ORR, which is ascribed to their unique 3D structure, low hydroxyl surface coverage and alloy properties.     

Ca[PO2(NH)3(CO)2]2 – The First Biuretooxophosphate with a Divalent Cation

Calcium biuretooxophosphate Ca[PO₂(NH)₃(CO)₂]₂ was synthesized by ion exchange reaction in aqueous solution. The crystal structure of the salt was elucidated by single‐crystal X‐ray diffraction. Anionic 1‐phospha‐2, 4, 6‐s‐triazine rings exhibiting a half‐chair conformation act as monodentate ligands for the calcium ions. A 3D network is formed by the resulting CaO₆ octahedrons together with the anionic rings interconnected by hydrogen bonds. Beside the crystal structure, FTIR and photoluminescence spectra of calcium biuretooxophosphate are discussed. The thermal behavior of the salt is examined by means of temperature‐dependent powder X‐ray diffraction measurements and combined TG and DTA analyses.     

Solvothermal Synthesis,Crystal Structure,and Properties of a New Organic‐Templated Holmium Sulfate with 1D Single Ladder Chains

A new organic amine templated 1D holmium sulfate (C₂H₈N)[Ho(SO₄)₂ · H₂O] ( 1 ) has been synthesized and solvothermally and structurally characterized by single‐crystal X‐ray diffraction, IR spectroscopy, thermogravimetric and X‐ray diffraction analyses as well as scanning electron microscopy (SEM). The structure of framework 1 is constructed from HoO₈ polyhedra and SO₄ tetrahedra. S(1) and S(2) connects Ho(1) and its crystallographic partners by using three S–O–Ho linkages to generate double chains, whereas the adjacent double chain are connected by μ₃‐O (O₅) atoms to form a novel single ladder chains.     

Zinc Coordination Complex for use in Uniform ZnS Microflowers Synthesis

Uniform snowball zinc sulfide (ZnS) microflowers with nanosheet covering were synthesized using the one step reaction of zinc coordination compounds with thiourea at 160 °C for 24 h. X‐ray single crystal diffraction, electron microscopy, energy‐dispersive X‐ray spectrometry, and X‐ray diffraction were used to characterize the products. The flower‐like ZnS crystals may have some application in catalyst or solar cell devices. This work is also expected to be applied in the fabrication of other transition metal sulfide crystals with special morphology.     

An Atomic View of Cation Diffusion Pathways from Single‐Crystal Topochemical Transformations

The diffusion pathways of Li‐ions as they traverse cathode structures in the course of insertion reactions underpin many questions fundamental to the functionality of Li‐ion batteries. Much current knowledge derives from computational models or the imaging of lithiation behavior at larger length scales; however, it remains difficult to experimentally image Li‐ion diffusion at the atomistic level. Here, by using topochemical Li‐ion insertion and extraction to induce single‐crystal‐to‐single‐crystal transformations in a tunnel‐structured V₂O₅ polymorph, coupled with operando powder X‐ray diffraction, we leverage single‐crystal X‐ray diffraction to identify the sequence of lattice interstitial sites preferred by Li‐ions to high depths of discharge, and use electron density maps to create a snapshot of ion diffusion in a metastable phase. Our methods enable the atomistic imaging of Li‐ions in this cathode material in kinetic states and provide an experimentally validated angstrom‐level 3D picture of atomic pathways thus far only conjectured through DFT calculations.     

Perfluoroalcohols: The Preparation and Crystal Structures of Heptafluorocyclobutanol and Hexafluorocyclobutane‐1,1‐diol

The first X‐ray crystal structure of an α‐fluoroalcohol is reported. Heptafluorocyclobutanol was obtained in quantitative yield from hexafluorocyclobutanone by HF addition in anhydrous hydrogen fluoride. The compound was characterized by its X‐ray single crystal structure. Heptafluorocyclobutanol readily undergoes hydrolysis to hexafluorocyclobutane‐1,1‐diol, which was also structurally characterized by X‐ray diffraction.     

Layered Electron Acceptors by Dimerization of Acenes End‐ Capped with 1,2,5‐Thiadiazoles

Layered electron acceptors D1 – 4 equipped with terminal 1,2,5‐thiadiazole groups have been constructed using a one‐pot protocol of acene dimerization. Their molecular structures are determined using single‐crystal X‐ray diffraction analysis. Photophysical and electrochemical properties of these molecules present a marked dependence on conjugation length and molecular geometry. An aggregation‐induced emission peak and an intramolecular excimer emission (IEE) band were observed for D2 and D4 , respectively. This work paves the way for the efficient synthesis of layered heteroacenes.     

Soft‐Chemical Exfoliation Route to Layered Cobalt Oxide Monolayers and Its Application for Film Deposition and Nanoparticle Synthesis

A colloidal suspension of exfoliated, layered cobalt oxide nanosheets has been synthesized through the intercalation of quaternary tetramethylammonium ions into protonated lithium cobalt oxide. According to atomic force microscopy, exfoliated nanosheets of layered cobalt oxide show a plateau‐like height profile with nanometer‐level height, underscoring the formation of unilamellar 2D nanosheets. The exfoliation of layered cobalt oxide was cross‐confirmed by X‐ray diffraction, UV/Vis spectroscopy, and transmission electron microscopy. The maintenance of the hexagonal in‐plane structure of the cobalt oxide lattice after the exfoliation process was evidenced by selected‐area electron diffraction and Co K‐edge X‐ray absorption near‐edge structure analysis. The zeta‐potential measurements clearly demonstrated the negative surface charge of cobalt oxide nanosheets. Adopting the nanosheets of layered cobalt oxide as a precursor, we were able to prepare the monodisperse CoO nanocrystals with a particle size of ≈10 nm as well as the heterolayered film composed of cobalt oxide monolayer and polycation.     

Coordination Frameworks based on 3,5‐Bis(imidazole‐1‐yl)­pyridine and Aromatic Dicarboxylate Ligands: Synthesis,Crystal Structures,and Photoluminescent Properties

Three metal coordination polymers [Zn(bdc)(L)(H₂O)]_n ( 1 ), [Co(pta)(L)(H₂O)₂]_n ( 2 ), and [Cd(tda)(L)(H₂O)]_n ( 3 ) [H₂bdc = 1,2‐benzene dicarboxylate acid, H₂pta = terephthalic acid, H₂tda = 2,5‐thiophenedicarboxylic acid, L = 3,5‐bis(imidazole‐1‐yl)pyridine] were synthesized and structurally characterized by IR spectroscopy, elemental analysis, X‐ray powder diffraction, and X‐ray single crystal diffraction. Complex 1 shows a three‐dimensional (3D) structure with cco topology with the symbol 6⁵ · 8, whereas complex 2 features a 3D structure with cds topology with the symbol 6⁵ · 8. Complex 3 has a 2D network constructed by the cadmium atoms bridged through the ligands tda and L. Their X‐ray powder diffraction patterns were compared with the simulated ones. Moreover, their luminescent properties were investigated in the solid state at room temperature, and the thermogravimetric analyses were carried out to study the thermal stability of the 3D networks.     

Synthesis,Characterization, and Photoluminescence Properties of a Planar Copper Triazolate Coordination Polymer with Cyanide as Co‐Ligand

A new copper coordination polymer [Cu₃(CN)(dmtz)₂] ( 1 ) (Hdmtz = 3,5‐dimethyl‐1,2,4‐triazole) was solvothermally synthesized and characterized by IR spectroscopy, X‐ray power diffraction, and single‐crystal X‐ray diffraction. The single‐crystal diffraction analysis shows that compound 1 belongs to the orthorhombic space group Pmmn, and exhibits a 2D planar framework constructed by the ligand dmtz and cyanide anions, in which the cyanide anion was generated from in situ decomposition of acetonitrile. The photoluminescent study indicates that 1 emits strong blue‐green luminescence with long emission lifetimes in the solid state at room temperature.     

Sonochemical synthesis of a two‐dimensional supramolecular polymer with nanoporous morphology,linear thallophilic and covalent hydrogen‐bonding interactions

A new thallium‐based supramolecular polymer [Tl(μ₃–3‐HClb)(μ₃–3‐Clb)]_n ( 1 ), (3‐HClb = 3‐chloroperbenzoic acid), has been synthesized and structurally characterized by single crystal X‐ray crystallography. It has a two‐dimensional structure with linear thallophilic and covalent hydrogen‐bonding interactions. In order to evaluate the effects of concentration, ultrasonic irradiation and type of solvents on structure, morphology and thermal behavior of 1 , some experiments were designed, and eight samples of 1 were synthesized under different conditions. These samples were characterized by IR spectroscopy, thermogravimetric and differential thermal analyses, X‐ray powder diffraction and scanning electron microscopy.     

Direct Synthesis of PbO Nanoparticles From a Lead(II) Nano Coordination Polymer Precursor: Synthesis,Crystal Structure,and DFT Calculations of [Pb2(dmp)2(μ‐N3)2(μ‐ClO4)2]n with the First Pb2‐(μ‐ClO4)2 Unit

Nanostructures of a new coordination polymer of divalent lead with the ligand 2, 9‐dimethyl‐1, 10‐phenanthroline (dmp) containing the first Pb₂‐(μ‐ClO₄)₂ motif, [Pb₂(dmp)₂(μ‐N₃)₂(μ‐ClO₄)₂]_n ( 1 ), was synthesized by a sonochemical method that produces the coordination polymers at nano size. The new nanostructure was characterized by scanning electron microscopy, X‐ray powder diffraction, IR, ¹H NMR and ¹³C NMR spectroscopy, and elemental analysis. Compound 1 was structurally characterized by single‐crystal X‐ray diffraction and the single‐crystal X‐ray data shows that the coordination number of Pb^II ions is six, (PbN₄O₂), with two N‐donor atoms from aza‐aromatic base ligands and four O‐donors from two perchlorate anions and two N‐donors from two azide anions. It has a “stereo‐chemically active” electron lone pair, and the coordination sphere is hemidirected. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The chains interact with each other through π–π stacking interactions creating a 3D framework. The structure of the title complex was optimized by density functional theory calculations. Calculated structural parameters and IR spectra for the title complex are in agreement with the crystal structure. The PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The average diameter of the nanoparticles was estimated by the Scherrer equation to be 23 nm. The morphology and size of the prepared PbO samples were further observed using SEM.     

Three Coordination Polymers based on 3,5‐Bis(imidazole‐1‐yl)pyridine and Benzoic Acid: Synthesis,Crystal Structures and Photoluminescent Properties

Three metal coordination polymers {[Co(L)₂(H₂O)₂]²⁺ · 2NO₃^–}_n ( 1 ), {[Mn(L)₂(H₂O)₂]²⁺ · 2Cl^– · 3H₂O}_n ( 2 ), and [ZnL(ba)₂]_n ( 3 ) [L = 3,5‐bis(imidazole‐1‐yl)pyridine and Hba = benzoic acid] were synthesized and structurally characterized by IR spectroscopy, elemental analysis, X‐ray powder diffraction, and X‐ray single crystal diffraction. Complex 1 shows a one‐dimensional (1D) chain structure. Adjacent chains are connected by hydrogen bonding and nitrate groups to form a 3D network. Complex 2 features a 2D layer structure. A three‐dimensional network is constructed through the cluster consisting of two chloride ions and three water molecules. Complex 3 shows a 1D zigzag chain structure that further twists together to form a 3D network. The X‐ray powder diffraction patterns were compared with the simulated ones. Moreover, the luminescent properties of 1 – 3 were investigated in the solid state at room temperature, and the thermogravimetric analyses were carried out to study the thermal stability of the three complexes.     

Metallogels Derived from Silver Coordination Polymers of C3‐Symmetric Tris(pyridylamide) Tripodal Ligands: Synthesis of Ag Nanoparticles and Catalysis

By applying a recently developed crystal engineering rationale, four C₃ symmetric tris(pyridylamide) ligands namely 1,3,5‐tris(nicotinamidomethyl)‐2,4,6‐triethylbenzene, 1,3,5‐tris(isonicotinamidomethyl)‐2,4,6‐triethylbenzene, 1,3,5‐tris(nicotinamidomethyl)‐2,4,6‐trimethylbenzene, and 1,3,5‐tris(isonicotinamidomethyl)‐2,4,6‐trimethylbenzene, which contain potential hydrogen‐bonding sites, were designed and synthesized for generating Ag^I coordination polymers and coordination‐polymer‐based gels. The coordination polymers thus obtained were characterized by single‐crystal X‐ray diffraction. The silver metallogels were characterized by transmission electron microscopy (TEM) and dynamic rheology. Upon exposure to visible light, these silver metallogels produced silver nanoparticles (AgNPs), which were characterized by TEM, powder X‐ray diffraction, energy dispersive X‐ray and X‐ray photoelectron spectroscopy. These NPs were found to be effectively catalyzed the reduction of 4‐nitrophenolate to 4‐aminophenolate without the use of any exogenous reducing agent.     

3D Electron Diffraction Unravels the New Zeolite ECNU‐23 from the “Pure” Powder Sample of ECNU‐21

A novel crystalline high‐silica zeolite with 12×8‐membered ring (R) channel system is prepared with the aid of the 3D electron diffraction (3D ED) technique. A crystal with the same topology as one of the predicted daughter structures of CIT‐13 germanosilicate, named ECNU‐23 (East China Normal University 23) was coincidentally detected by the 3D ED investigation during the structure characterization of the “pure” powder sample of existing one‐dimension (1D) 10‐R ECNU‐21. By controlling the alkaline‐assisted hydrolysis under moderate conditions, we purified the phase of ECNU‐23 by selectively breaking and removing the chemically weak Ge(Si)‐O‐Ge and metastable Si‐O‐Si bonds. Its structure was determined based on the 3D ED data, and confirmed by high‐resolution TEM images and powder X‐ray diffraction (PXRD) data. The aluminosilicate Al‐ECNU‐23 shows unique catalytic properties in the isomerization/ disproportionation of m‐xylene as solid‐acid catalyst.     

Resolving the Differences Between the 1.9 Å and 1.95 Å Crystal Structures of Photosystem II: A Single Proton Relocation Defines Two Tautomeric Forms of the Water‐Oxidizing Complex

Great progress has been made in characterizing the water‐oxidizing complex (WOC) in photosystem II (PSII) with the publication of a 1.9 Å resolution X‐ray diffraction (XRD) and recently a 1.95 Å X‐ray free‐electron laser (XFEL) structure. However, these achievements are under threat because of perceived conflicts with other experimental data. For the earlier 1.9 Å structure, lack of agreement with extended X‐ray absorption fine structure (EXAFS) data led to the notion that the WOC suffered from X‐ray photoreduction. In the recent 1.95 Å structure, Mn photoreduction is not an issue, but poor agreement with computational models which adopt the ‘high’ oxidation state paradigm, has again resulted in criticism of the structure on the basis of contamination with lower S states of the WOC. Here we use DFT modeling to show that the distinct WOC geometries in the 1.9 and 1.95 Å structures can be straightforwardly accounted for when the Mn oxidation states are consistent with the ‘low’ oxidation state paradigm. Remarkably, our calculations show that the two structures are tautomers, related by a single proton relocation.     

Superconductivity in a Copper(II)‐Based Coordination Polymer with Perfect Kagome Structure

A highly crystalline copper(II) benzenehexathiolate coordination polymer (Cu‐BHT) has been prepared. The two‐dimensional kagome structure has been confirmed by powder X‐ray diffraction, high‐resolution transmission electron microscopy, and high‐resolution scanning transmission electron microscopy. The as‐prepared sample exhibits bulk superconductivity at about 0.25 K, which is confirmed by the zero resistivity, AC magnetic susceptibility, and specific heat measurements. Another diamagnetic transition at about 3 K suggests that there is a second superconducting phase that may be associated with a single layer or few layers of Cu‐BHT. It is the first time that superconductivity has been observed in a coordination polymer.