Synthesis of Organic–Inorganic Hybrid Nanocomposites via a Simple Two-Phase Ligands Exchange

2020 ◽  
Vol 12 (3) ◽  
pp. 326-332 ◽  
Author(s):  
Hyun Sung Noh ◽  
Jaehan Jung
Keyword(s):  
Ligand Exchange ◽  
Hybrid Nanocomposites ◽  
Azide Group ◽  
Two Phase ◽  
H Nmr ◽  
Bifunctional Ligands ◽  
Chemical Coupling ◽  
Inorganic Nanocomposites ◽  
Ligands Exchange ◽  
Click Coupling

The surface of nanocrystals (NCs) was precisely engineered with bifunctional ligands via a simple yet effective two-phase ligand exchange strategy where the introduction of bifunctional ligands and displacement of insulating aliphatic ligands are simultaneously occurred. This is advantageous compared to conventional ligands exchange procedure where the desired ligands are often introduced through two-step processes after treating NC surface with short mobile ligands such as pyridine or short amines. In this study, 4-azidobenzoic acid possessing carboxylic acid for binding with NCs and azide group for chemical coupling was utilized as bifunctional ligands. A correlation between the concentration and the efficiency of ligands replacement was corroborated by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (1H NMR) spectroscopy measurement. Lastly, organic–inorganic nanocomposites were crafted via click coupling between 1-octyne and azidobenzoic acid capped CdSe NCs. The success of coupling was substantiated by FTIR and 1H NMR.

Mechanistische Untersuchungen zum reversiblen Gleichgewicht von metallorganischen Tripeldecker- und Sandwichkomplexen des Typs [Bis{(η5-CpR)Co}-μ-{η4:η4-aren}] und [(η5-CpR)Co(η6-aren)] / Mechanistic Studies towards the Reversible Equilibrium between Metal Organic Triple Decker and Sandwich Complexes [Bis{(η5 -CpR)Co}-μ-{η4 :η4-arene}] and [{(η5-CpR)Co(η6-arene)]

1998 ◽  
Vol 53 (11) ◽  
pp. 1267-1272 ◽  
Author(s):  
Jörg J. Schneider ◽  
Dirk Wolf
Keyword(s):  
Ligand Exchange ◽  
Sandwich Complexes ◽  
Valuable Metal ◽  
H Nmr ◽  
Synthetic Utility ◽  
Metal Organic ◽  
Arene Ligand ◽  
Benzene Toluene

The arene ligand exchange mechanism of slipped arene triple deckers [Bis{(η5-CpR)Co}-μ-{η4:η4-arene}] (R = Me5, 1,2,4 tri-tert butyl, arene = benzene, toluene) 1 was studied by 1H-NMR spectroscopy for different concentrations and solvents. It has been found that triple deckers of type 1 decompose slowly in solution. A unique equilibrium, between these triple deckers and the mixed sandwich complexes [(η6-arene)Co(η5-CpR)] and 14 e [(η5-Cp)Co]solv fragments generated in situ by decomposition o f 1 exists. In addition to this equilibrium arene lability of the thus formed mixed sandwich complex type has been detected by NMR making slipped triple deckers 1 ideal single source compounds for the generation of two [(η5-Cp)Co] fragments in one reaction step. Such fragments are valuable metal ligand components with high synthetic utility in organometallic chemistry.

Determination of mechanical properties of two-phase and hybrid nanocomposites: experimental determination and multiscale modeling

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mahmoud Haghighi ◽  
Hossein Golestanian ◽  
Farshid Aghadavoudi
Keyword(s):  
Mechanical Properties ◽  
Ultimate Strength ◽  
Multiscale Modeling ◽  
Filler Content ◽  
Hybrid Nanocomposites ◽  
Dynamics Simulation ◽  
Strength Increase ◽  
Two Phase ◽  
Macro Scale ◽  
Elongation To Failure

Abstract In this paper, the effects of filler content and the use of hybrid nanofillers on agglomeration and nanocomposite mechanical properties such as elastic moduli, ultimate strength and elongation to failure are investigated experimentally. In addition, thermoset epoxy-based two-phase and hybrid nanocomposites are simulated using multiscale modeling techniques. First, molecular dynamics simulation is carried out at nanoscale considering the interphase. Next, finite element method and micromechanical modeling are used for micro and macro scale modeling of nanocomposites. Nanocomposite samples containing carbon nanotubes, graphene nanoplatelets, and hybrid nanofillers with different filler contents are prepared and are tested. Also, field emission scanning electron microscopy is used to take micrographs from samples’ fracture surfaces. The results indicate that in two-phase nanocomposites, elastic modulus and ultimate strength increase while nanocomposite elongation to failure decreases with reinforcement weight fraction. In addition, nanofiller agglomeration occurred at high nanofiller contents especially higher than 0.75 wt% in the two-phase nanocomposites. Nanofiller agglomeration was observed to be much lower in the hybrid nanocomposite samples. Therefore, using hybrid nanofillers delays/prevents agglomeration and improves mechanical properties of nanocomposite at the same total filler content.

scholarly journals A bipyridine-ligated zinc(II) complex with bridging flavonolate ligation: synthesis, characterization, and visible-light-induced CO release reactivity

2017 ◽  
Vol 73 (9) ◽  
pp. 703-709 ◽  
Author(s):  
Shayne Sorenson ◽  
Marina Popova ◽  
Atta M. Arif ◽  
Lisa M. Berreau
Keyword(s):  
Visible Light ◽  
Ligand Exchange ◽  
Distorted Octahedral Geometry ◽  
Conductivity Measurements ◽  
Bidentate Coordination ◽  
H Nmr ◽  
Distorted Octahedral ◽  
Spectroscopic Identification ◽  
Synthetic Models ◽  
Weak Coordination

Metal–flavonolate compounds are of significant current interest as synthetic models for quercetinase enzymes and as bioactive compounds of importance to human health. Zinc–3-hydroxyflavonolate compounds, including those of quercetin, kampferol, and morin, generally exhibit bidentate coordination to a single ZnII center. The bipyridine-ligated zinc–flavonolate compound reported herein, namely bis(μ-4-oxo-2-phenyl-4H-chromen-3-olato)-κ3 O 3:O 3,O 4;κ3 O 3,O 4:O 3-bis[(2,2′-bipyridine-κ2 N,N′)zinc(II)] bis(perchlorate), {[Zn2(C15H9O3)2(C10H8N2)2](ClO4)2} n , (1), provides an unusual example of bridging 3-hydroxyflavonolate ligation in a dinuclear metal complex. The symmetry-related ZnII centers of (1) exhibit a distorted octahedral geometry, with weak coordination of a perchlorate anion trans to the bridging deprotonated O atom of the flavonolate ligand. Variable-concentration conductivity measurements provide evidence that, when (1) is dissolved in CH3CN, the complex dissociates into monomers. 1H NMR resonances for (1) dissolved in d 6-DMSO were assigned via HMQC to the H atoms of the flavonolate and bipyridine ligands. In CH3CN, (1) undergoes quantitative visible-light-induced CO release with a quantum yield [0.004 (1)] similar to that exhibited by other mononuclear zinc–3-hydroxyflavonolate complexes. Mass spectroscopic identification of the [(bpy)2Zn(O-benzoylsalicylate)]+ ion provides evidence of CO release from the flavonol and of ligand exchange at the ZnII center.

scholarly journals Protected Gold Nanoparticles with Thioethers and Amines As Surrogate Ligands

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
M. Rafiq H. Siddiqui
Keyword(s):  
Gold Nanoparticles ◽  
Variable Temperature ◽  
Size Control ◽  
Analytical Techniques ◽  
High Resolution Electron Microscopy ◽  
Phase Method ◽  
Two Phase ◽  
H Nmr ◽  
Resolution Electron ◽  
Vis Spectroscopy

Dodecyl sulfide, dodecyl amine, and hexylamine were shown to act as surrogate ligands (L) via metastable gold nanoparticles. By collating analytical and spectroscopic data obtained simultaneously, empirical formula Au24L was assigned. These impurity-free nanoparticles obtained in near quantitative yields showing exceptional gold assays (up to 98%Au) were prepared by a modification of the two-phase method. Replacement reactions on the Au24L showed that Au:L ratios may be increased (up to Au55:L (L= (H25C12)2S)) or decreased (Au12:L (L= H2NC12H25and H2NC6H13)) as desired. This work encompassing the role of analytical techniques used, that is, elemental analysis, variable temperature1H NMR, FAB mass spectrometry, UV-Vis spectroscopy, thin film X-ray diffraction, and high-resolution electron microscopy (HREM) has implications in the study of size control, purity, stability, and metal assays of gold nanoparticles.

Synthesis, conformational studies, and inclusion properties of tris[(2-pyridylmethyl)oxy]hexahomotrioxacalix[3]arenes

1998 ◽  
Vol 76 (7) ◽  
pp. 989-996 ◽  
Author(s):  
Takehiko Yamato ◽  
Mitsuteru Haraguchi ◽  
Jun-Ichi Nishikawa ◽  
Seiji Ide ◽  
Hirohisa Tsuzuki
Keyword(s):  
Alkylation Reaction ◽  
Alkali Metal Cations ◽  
Template Effect ◽  
Two Phase ◽  
Conformational Studies ◽  
Preferential Formation ◽  
H Nmr ◽  
Inclusion Properties ◽  
Partial Cone

O-Alkylation of the flexible macrocycle 1 with 2-(chloromethyl)pyridine in the presence of Cs2CO3 resulted in the preferential formation of partial-cone-2. The cone-to-partial-cone ratio of 2 increased in the presence of K2CO3, and led to almost equal in the presence of NaH. The template effect of the alkali metal cations plays an important role in this O-alkylation reaction. The structural characterization of these products is also discussed. The two-phase solvent extraction data indicated that tris[(2-pyridylmethyl)oxy]hexahomotrioxacalix[3]arenes 2 show moderate extractability for n-butylammonium ion and high extractability for Ag+. The 1H NMR titration of cone-2 with AgSO3CF3 clearly demonstrates that a 1:1 complex is formed, which is stable on the NMR time scale. Thus, the synergism of cyclophane moiety and two or three lower-rim side chains with pyridyl groups play a significant role on the complexation of tris[(2-pyridylmethyl)oxy] derivatives cone-2 and partial-cone-2 with Ag+ ion and n-butylammonium ion.Key words: macrocycles, calixarenes, O-alkylation, ionophores, cation-N interaction.

scholarly journals Synthesis of Fluorinated Amphiphilic Block Copolymers Based on PEGMA, HEMA, and MMA via ATRP and CuAAC Click Chemistry

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Fatime Eren Erol ◽  
Deniz Sinirlioglu ◽  
Sedat Cosgun ◽  
Ali Ekrem Muftuoglu
Keyword(s):  
Block Copolymer ◽  
Block Copolymers ◽  
Amphiphilic Block Copolymers ◽  
Random Copolymers ◽  
Side Chain ◽  
Dipolar Cycloaddition ◽  
Controlled Synthesis ◽  
H Nmr ◽  
Ft Ir ◽  
Click Coupling

Synthesis of fluorinated amphiphilic block copolymers via atom transfer radical polymerization (ATRP) and Cu(I) catalyzed Huisgen 1,3-dipolar cycloaddition (CuAAC) was demonstrated. First, a PEGMA and MMA based block copolymer carrying multiple side-chain acetylene moieties on the hydrophobic segment for postfunctionalization was carried out. This involves the synthesis of a series of P(HEMA-co-MMA) random copolymers to be employed as macroinitiators in the controlled synthesis of P(HEMA-co-MMA)-block-PPEGMA block copolymers by using ATRP, followed by a modification step on the hydroxyl side groups of HEMA via Steglich esterification to afford propargyl side-functional polymer, alkyne-P(HEMA-co-MMA)-block-PPEGMA. Finally, click coupling between side-chain acetylene functionalities and 2,3,4,5,6-pentafluorobenzyl azide yielded fluorinated amphiphilic block copolymers. The obtained polymers were structurally characterized by1H-NMR,19F-NMR, FT-IR, and GPC. Their thermal characterizations were performed using DSC and TGA.

scholarly journals Interface Engineering Strategies for Fabricating Nanocrystal-Based Organic–Inorganic Nanocomposites

2018 ◽  
Vol 8 (8) ◽  
pp. 1376 ◽  
Author(s):  
Jaehan Jung ◽  
Mincheol Chang ◽  
Hyeonseok Yoon
Keyword(s):  
Ligand Exchange ◽  
Intimate Contact ◽  
Future Directions ◽  
Electronic Interactions ◽  
Interfacial Engineering ◽  
Exchange Processes ◽  
Recent Developments ◽  
Direct Growth ◽  
Purification Methods ◽  
Inorganic Nanocomposites

Hybrid organic–inorganic nanocomposites have attracted considerable attention because they have the advantages of both conjugated polymers (CPs) and nanocrystals (NCs). Recent developments in the interfacial engineering of CP–NC organic–inorganic nanocomposites enabled the formation of an intimate contact between NCs and CPs, facilitating electronic interactions between these two constituents. To design CP–NC nanocomposites, several approaches have been introduced, including ligand refluxing, direct grafting methods, direct growth of NCs in proximity to CPs, and template-guided strategies. In this review, the general reactions of ligand exchange processes, purification methods, and characterization techniques have been briefly introduced. This is followed by a highlight of recent advances in the synthesis of hybrid CP–NC nanocomposites and newly developed inorganic surface treatments, as well as their applications. An outlook for future directions in this area is also presented.

Wolfram-Carbonylkomplexe mit Stickstoff-Wasserstoff-Liganden [1] / Tungsten Carbonyl Complexes with Nitrogen Hydride Ligands [1]

1978 ◽  
Vol 33 (5) ◽  
pp. 542-553 ◽  
Author(s):  
Dieter Sellmann ◽  
Alfred Brandl ◽  
Ralf Endeil
Keyword(s):  
Ligand Exchange ◽  
Nmr Spectra ◽  
Base Catalysis ◽  
Coupling Constants ◽  
Carbonyl Complexes ◽  
H Nmr ◽  
Nitrogen Hydride ◽  
Tungsten Carbonyl ◽  
Synthesis Properties ◽  
Hydride Ligands

Abstract Synthesis, properties and reactions of [(OC)5W]2N2H2, [(OC)5W]2N2H4, (OC)5WN2H4, (OC)5WNH3, [(OC)4PØ3W]2N2H4, [(OC)4PØ3WN2H4], [(OC)5W-N2H2-W(CO)4PØ3], [(OC)5W-N2H2-W(CO)4P(CH3)3] and [(OC)5WNHCH3NHC6H5] are reported. The hydrazine complexes are synthesized by ligand exchange from the corresponding tetra-hydrofuran complexes. Oxidation by various oxidizing agents yields the diazene complexes, in most cases very low yields. Substitution of CO by phosphanes leads to reduced stability of the compounds. All complexes undergo base catalysed H-D exchange yielding the corresponding ND derivatives; the diazene complexes show a much faster exchange than the corresponding hydrazine and ammonia complexes, which is explained by the higher acidity of the N2H2 protons. The diazene complexes disproportionate under base catalysis to hydrazine and dinitrogen compounds, the latter of which loose the N2 ligand immediately. The diazene ligand of [(OC)5W]2N2H2 cannot be alkylated by reactions with (CH3)2SO4, LiCH3 or CH2N2; instead, LiCH3 as well as CH2N2 cause disproportionation to N2H4 and N2 complexes. UV irradiation of [(OC)5W]2N2H2 in THF leads to substitution of CO by THF. The THF complexes can be converted to the phosphane substituted diazene complexes. The IR, UV-VIS and 1H NMR spectra of the (OC)5W complexes are nearly identical to those of the analogous Cr and Mo compounds. The unsymmetrical phosphane diazene complexes, however, show a quartet of the N2H2 protons in the 1H NMR spectra with coupling constants of 25-26 Hz for the protons on the NN double bond. This value points to a trans configuration of the diazene ligand and its complexes respectively.

A NMR Study of the Exchange Kinetics of the Nonamethylimidodiphosphoramide with its Complexes of Diamagnetic Cations

1978 ◽  
Vol 33 (6) ◽  
pp. 684-685 ◽  
Author(s):  
P. R. Rubini ◽  
L. Rodehüser ◽  
J.-J. Delpuech
Keyword(s):  
Nmr Spectroscopy ◽  
Ligand Exchange ◽  
H Nmr ◽  
Nmr Study ◽  
Exchange Kinetics ◽  
Monodentate Ligands ◽  
Kinetics Of

Abstract The ligand exchange on nonamethylimidodiphosphoramide (NIPA) complexes is found to be very slow comparatively to analogous monodentate ligands; the rates determined by 1H or 31P NMR spectroscopy are: k(25°C)=4.3 × 10-2 s-1; 31.6 s-1 • M-1; 3.7 × 104 S-1 • M-1 and 1.35 × 104 s-1 · M-1 for Mg2+, Ca2+, Sr2+ and Li+ cations respectively. For the Al3+, Ga3+, In3+ and Be2+ ions no exchange could be detected by 1H NMR spectroscopy up to 120 °C, indicating rates lower than about 10-3 s-1

NMR kinetic study of ligand exchange on a (µ-oxo)bis(µ-acetato)diruthenium(III) complex. A special kinetic case of introduction of a more labile ligand

1997 ◽  
Vol 75 (6) ◽  
pp. 890-898 ◽  
Author(s):  
Joana Mara Santos ◽  
Cecília Cipriano ◽  
Roberto B. Faria ◽  
J. Daniel Figueroa-Villar
Keyword(s):  
Ligand Exchange ◽  
Chemical Shifts ◽  
Variable Temperature ◽  
Forward Direction ◽  
Reverse Direction ◽  
H Nmr ◽  
Diruthenium Complex ◽  
Solvent Substitution ◽  
Kinetics Of ◽  
Oxo Bridge

We have prepared the new [Ru2(μ-O)(μ-O2CCH3)2(4-pic)6](PF6)2 complex and followed the kinetics of exchange of the 4-picoline ligands, trans to the oxo bridge, with dimethyl sulfoxide (DMSO-d6) by 1H NMR at 30, 40, 50, and 60 °C. The 1H NMR spectra of this complex in DMSO gradually change in the acetyl methyl region as solvent substitution of the 4-picoline trans to the oxo bridge takes place. This substitution is in accordance with the lability of the ligands trans to the RuIII-O-RuIII bridge in this kind of complex. The kinetic data fit in a series of double reversible reactions, pseudo first order in the forward direction and second order in the reverse direction, with ΔH≠ = 115, 105, 116, and 106 kJ mol−1 and ΔS≠ = 35.7, 17.2, 38.8, and 16.9 JK−1 mol−1 associated with k1, k−1, k2, and k−2 rate constants, respectively.[Formula: see text]A, B and C stand for the nonexchanged, monoexchanged, and diexchanged complexes, respectively. The large ΔH≠ and positive ΔS≠ values agree with the dissociative nature of the mechanism in both forward and reverse reactions. The differences in 1H and I3C NMR chemical shifts of the three complexes are explained in terms of the effect of the ligand exchange on the N—Ru bond lengths and the geometry of the dimetal core. It is evident from our data that the exchange on one metallic site modifies the reactivity at the other site in this kind of dinuclear complex. Keywords: diruthenium complex, variable temperature NMR, ligand exchange kinetics.

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