Syntheses and Crystal Structures of Two Inorganic–Organic Hybrid Frameworks Constructed from Pyridine-2,5-Dicarboxylic Acid

Two novel inorganic–organic hybrid frameworks of [Co(2,5-pydc)(4,4′-bipyo)_0.5(H₂O)₃ · 3H₂O] _n (1) and [Cu_1.5Gd(2,5-pydc)₃(2,2′-bipyo)(H₂O)₄ · 2H₂O] _n (2) (2,5-pydc = pyridine-2,5-dicarboxylic acid; 4,4′-bipyo = 4,4′-bipyridine-N,N′-dioxide; 2,2′-bipyo = 2,2′-bipyridine-N,N′-dioxide) were prepared. Both compounds have been characterized by the elemental analyses, IR spectra, TG analysis and the single crystal diffraction. The salient structural feature for both compounds 1 and 2 is that the 1D chain and the mononuclear fragment are connected by strong hydrogen bond interactions to form 2D structure.     

In Situ Generation of Strong Bases from Alkaline and Alkaline–Earth Carbonates

Strong bases from alkaline and alkaline-earth metal carbonates were generated in situ by adding a small amount of acetic acid at reflux in toluene under water-free conditions. Their basic strength reached superbasicity thus changing the color of 4-chloroaniline (H₋=26.5). The high conversion of ethyl acetate in its self-condensation over decomposed carbonates, which require strong basicity to abstract protons from ethyl acetate (pK_a=25), also confirmed the formation of strong bases. Adding acetic acid during the reaction indicated that metal oxides—decomposed materials from carbonates—were responsible for their high catalytic activity. The lack of sufficient coordination of in situ generated metal oxides was considered to be a plausible cause for their strong basicity.     

Structural Effect of Pincer Pd(II)–ONO Complexes Modified with Acylthiourea on Sizes of the In Situ Generated Pd Nanoparticles During Heck Coupling Reaction

Catalysis Letters - The Pd nanoparticles generated in situ from Pd–pincer complexes catalyzed Heck coupling reaction. For this purpose, new Pd(II)–ONO pincer complexes (1–4)...     

Interphase Distribution of Lanthanide Salts in Multicomponent Aqueous–Organic Two-Phase Systems

Theoretical Foundations of Chemical Engineering - The interphase distribution of lanthanide salts in ternary aqueous–organic systems of various compositions has been studied. It has been...     

Construction of Two New Metal–Organic Frameworks from Pamoic Acid and N-Containing Auxiliary Ligands

Two new metal–organic frameworks; namely, [Cd₂(pam)₂(bpe)_1.5(DMF)₂(H₂O)] _n ·2n(DMF) (1) and [Cd(pam)(bix)] _n (2) (H₂pam = pamoic acid, bpe = 1,2-di(4-pyridyl)ethylene, bix = 4,4′-bis(imidazol-1-ylmethyl)benzene, DMF = N,N′-dimethylformamide), were solvothermally synthesized via varying the auxiliary ligand. Single crystal X-ray diffraction analysis reveals that compound 1 shows a 2D→3D polythreaded motif based on (3,4)-connected 2D sheets, while compound 2 features a 4-connected sql tetragonal plane net, which further extended into a 3D supramolecular framework through intermolecular CH···π interactions. In addition, the luminescent and thermal stabilities properties of these two compounds were investigated.     

Hydrothermal Synthesis of Metal–Organic Coordination Polymers Constructed from Asymmetric Semi-rigid V-shaped Dicarboxylate and Nitrogen-Contained Mixed Ligands

Three new coordination polymers, [Ni(2,4′-oba)(1,10-phen)] _n (1), {[Ni (2,4′-Hoba)₂(4,4′-bipy)(H₂O)₂]·2H₂O} _n (2) and [Zn(2,4′-oba) (4,4′-bipy)] _n (3) (2,4′-H₂oba = 2-(4-carboxyphenoxy)benzoic acid, 1,10- phen = 1,10-phenanthroline, and 4,4′-bipy = 4,4′-bipyridine) have been obtained by hydrothermal synthesis. The framework structures of these polymeric complexes have been determined by single-crystal X-ray diffraction studies. Complex 1 exhibits double-helical chains formed by π–π stacking interactions from the phenyl rings of the 1,10-phen ligands. Complex 2 forms a two-dimensional supramolecular architecture directed by hydrogen bonding. Complex 3 exhibits a three-dimensional structure; Schl?fli symbol of {4⁴·6¹⁰·8}. The luminescent property of compound 3 is discussed.     

In Situ Generation of Two-Dimensional Au–Pt Core–Shell Nanoparticle Assemblies

Two-dimensional assemblies of Au–Pt bimetallic nanoparticles are generated in situ on polyethyleneimmine (PEI) silane functionalized silicon and indium tin oxide (ITO) coated glass surfaces. Atomic force microscopy (AFM), UV–Visible spectroscopy, and electrochemical measurements reveal the formation of core–shell structure with Au as core and Pt as shell. The core–shell structure is further supported by comparing with the corresponding data of Au nanoparticle assemblies. Static contact angle measurements with water show an increase in hydrophilic character due to bimetallic nanoparticle generation on different surfaces. It is further observed that these Au–Pt core–shell bimetallic nanoparticle assemblies are catalytically active towards methanol electro-oxidation, which is the key reaction for direct methanol fuel cells (DMFCs).     

Interphase Distribution of Lanthanide Chlorides in Multicomponent Aqueous–Organic Two-Phase Systems Containing DEHPA

Theoretical Foundations of Chemical Engineering - The interphase distribution of lanthanide chlorides in ternary aqueous–organic systems containing DEHPA has been studied as a function of the...     

A Novel Method for In Situ Synthesis of Nanostructure Hydroxyapatite–nylon 66 Composites in Tissue Engineering

An interfacial polymerization method for nylon 66 was adapted to produce nanostructured composites with nanohydroxyapatite (n-HA) via in situ polymerization. Nylon 66 was synthesized in n-HA slurry to increase homogeneity and biocompatibility. Synthesis powders was characterized by XRD, TEM, TGA, and FT-IR analysis. The results showed a uniform dispersion in composites, whereas needle-like, n-HA crystals dispersed in condensed polymer matrix. The samples were immersed in SBF for bioactivity tests in different periods, and results were monitored by SEM and EDX in terms of forming an apatite layer. The mechanical properties of the n-HA/nylon66 nanocomposites are discussed in terms of n-HA loading.     

Study of C─H⋯O Bond of Organic–Inorganic Hybrids Based on Polyhydroxybutyrate and Oxides Obtained Via an In Situ Sol–Gel Route

Sol–gel-based zirconia (ZrO₂) and silica (SiO₂) were obtained in situ via hydrolysis–polycondensation of metal alkoxide precursors in membranes of poly(3-hydroxybutyrate) (PHB). What followed was an assessment of thermal and spectroscopic effects from the insertion of the inorganic network in the PHB matrix. The findings exhibited a dependence of both the concentration and the chemical nature of the precursor on the properties of the as-formed inorganic–organic hybrids. The results also indicated that positive nucleating effects, a reduction of the crystallite size and a variation in thermal transitions correlate with spectroscopic data from the alpha and beta crystal forms of the PHB matrix, as well as the crystallization data obtained through polarized light microscopy. POLYM. ENG. SCI., 60:673–681, 2020. © 2020 Society of Plastics Engineers     

Luminescent Organic–Inorganic Hybrids of Functionalized Mesoporous Silica SBA-15 by Thio-Salicylidene Schiff Base

Novel organic–inorganic mesoporous luminescent hybrid material N,N′-bis(salicylidene)-thiocarbohydrazide (BSTC-SBA-15) has been obtained by co-condensation of tetraethyl orthosilicate and the organosilane in the presence of Pluronic P123 surfactant as a template. N,N′-bis(salicylidene)-thiocarbohydrazide (BSTC) grafted to the coupling agent 3-(triethoxysilyl)-propyl isocyanate (TESPIC) was used as the precursor for the preparation of mesoporous materials. In addition, for comparison, SBA-15 doped with organic ligand BSTC was also synthesized, denoted as BSTC/SBA-15. This organic–inorganic hybrid material was well-characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (HRTEM), and photoluminescence spectra, which reveals that they all have high surface area, uniformity in the mesostructure. The resulting materials (BSTC-SBA-15 and BSTC/SBA-15) exhibit regular uniform microstructures, and no phase separation happened for the organic and the inorganic compounds was covalently linked through Si–O bonds via a self-assemble process. Furthermore, the two materials have different luminescence range: BSTC/SBA-15 presents the strong dominant green luminescence, while BSTC-functionalized material BSTC-SBA-15 shows the dominant blue emission.     

Fabrication of Pd–Au Clusters by In Situ Spontaneous Reduction of Reductive Layered Double Hydroxides

Catalysis Letters - In this work, layered double hydroxides (LDHs) including the variable valence Co2+ ions (CoAl-LDHs) is discovered to be capable of serving as the support and the reducing agent...     

Studies of Heterogeneous Hydrothermal Stripping from Iron-loaded Naphthenic Acid–Alcohol–Kerosen

The technique of hydrothermal stripping from mixed aqueous-organic systems is a promising method for synthesizing oxide ceramic powders for high-performance applications. Some factors influencing heterogeneous hydrothermal stripping with water from iron-loaded organic phase of naphthenic acid–isooctyl alcohol–kerosene, such as initial concentrations of iron and naphthenic acid, concentration of Fe2O3 “seed”, temperature and time, were investigated. Based on the experimental results, the rate equation was established. Nano-ferric oxide powders were obtained by the technique of hydrothermal stripping from the iron-loaded organic phase. The results suggest that the heterogeneous hydrothermal stripping proceeds in 3 steps: adsorption of naphthenic acid dimers and naphthenic complex of iron onto the surface of “seed”, hydrolysis of adsorbed complex of iron, and condensation of hydrolyzed complex. The process activation energy is 115 kJ/mol and the heterogeneous hydrothermal stripping is controlled by a chemical reaction (the hydrolysis of naphthenic complex of iron).     

In Vivo Expression of Genetic Information from Phosphoramidate–DNA

Chemically modified genes and genomes with customized properties will become a valuable tool in numerous fields, including synthetic biology, biotechnology, and medicine. These genetic materials are meant to store and exchange information with DNA and RNA while tuning their functionality. Herein, we outline the development of an alternative genetic system carrying phosphoramidate linkages that successfully propagates genetic information in bacteria and at the same time is labile to acidic conditions. The P3′→N5′ phosphoramidate-containing DNA (PN-DNA) was enzymatically synthesized by using 5′-amino-2′,5′-deoxycytidine 5′-N-triphosphates (NH-dCTPs) as substrates for DNA polymerases and employed to encode antibiotic resistance in Escherichia coli. The resulting PN-DNA can be efficiently destroyed by mild acidic conditions, whereas an unmodified counterpart remains intact. A cloning strategy was proposed for assembling modified fragments into a genome. This method can be of interest to scientists working in the field of orthogonal nucleic acid genes and genomes.     

Synthesis, Crystal Structures and Properties of Two Metal–Organic Frameworks Constructed from Pyridine Dicarboxylate and Flexible Bis(imidazole) Ligand

Two novel interesting metal–organic frameworks, [Zn(PDA)(bbi)] _n (1) and [Cd₂(PDA)₂(bbi)₂(H₂O)₂·10H₂O] _n (2) [H₂PDA = pyridine-2,6-dicarboxylic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole)] have been isolated under hydrothermal conditions and structurally characterized. X-ray single crystal structure analysis reveals that complex 1 crystallize in monoclinic P2₁/c space group, while complex 2 crystallize in triclinic P-1 space group. The PDA^2? anions act in two different coordination modes: terminal chelating for 1 and chelating and bis-monoatomic bridging for 2. Polymeric chains of 1 and 2 are composed of Zn(II) and Cd(II) ions bridged by bbi ligands. The fluorescent properties of 1 and 2 were also investigated.     

Silver Electrodeposition from AgNO3 Solutions Containing Organic Additives: Electrodeposition from Binary Water–Methanol Solvent Systems in the Presence of Tartaric Acid

The electrodeposition of silver at 25 °C from AgNO₃/tartaric acid solutions in binary water–methanol solvent systems was investigated. This study shows that it is possible to obtain compact and coherent silver deposits from AgNO₃ solutions only in the presence of tartaric acid (H₂A). The relevant chemical entity controlling growth inhibition is a neutral associate Ag(HA) formed in the solution between Ag⁺ and tartaric monoanions HA^–. Most of the structural features of Ag deposits such as grain size, surface roughness and degree of the preferred orientation 1 1 0, depend on the concentration of this associate. These properties of the deposits can easily be controlled by:(a) modifying the concentration of AgNO₃ or H₂A, (b) adjusting the pH of the bulk solution by addition of HNO₃ and (c) modifying the composition of the mixed solvent system.