Search results for "Ionic polymerization"
showing 10 items of 481 documents
Molecular-Programmed Self-Assembly of Homo- and Heterometallic Tetranuclear Coordination Compounds: Synthesis, Crystal Structures, and Magnetic Prope…
2009
New homo- and heterobimetallic tetranuclear complexes of formula [Cu4(mpba)(Me4en)4(H2O)4](ClO4)4·3H2O (1), [Cu4(mpba)(Me4en)4(H2O)4](PF6)4·2H2O (2), [Cu4(ppba)(Me4en)4(H2O)4](ClO4)4·2H2O (3), [Cu4(mpba)(dipn)4](ClO4)4·3H2O (4), [Cu4(ppba)(dipn)4](ClO4)4·2H2O (5), and [Cu2Ni2(ppba)(dipn)4(H2O)2](PF6)4 (6) [mpba = N,N′-1,3-phenylenebis(oxamate), ppba = N,N′-1,4-phenylenebis(oxamate), Me4en = N,N,N′,N′-tetramethylethylenediamine, and dipn = dipropylenetriamine] have been synthesized and structurally and magnetically characterized. Complexes 1−6 have been prepared following a molecular-programmed self-assembly method, where a heteropolytopic tetranucleating phenylenedioxamato bridging ligand (…
About the relevance of anion-π interactions in water.
2021
Anion-π interactions are emerging as exotic features with potential applications in chemistry. In the last years, their relevance in living systems has been outlined, and so far there is no concluding significant evidence recognized about the participation of anion-π interactions in water because anion-π sensors contain large aromatic hydrophobic surfaces with limited solubility. By transforming a neutral heterocycle (for example quinoline) into its corresponding salt (quinolinium), we have been able to overcome these solubility issues, and new cationic water-soluble fluorophores have been prepared. Herein, we used N-alkylated heterocycles as π-acidic surfaces to shed light on the nature of…
2D and 3D bimetallic oxalate-based ferromagnets prepared by insertion of different FeIII spin crossover complexes
2010
The syntheses, structures and magnetic properties of the compounds of formula [Fe(III)(5-NO(2)sal(2)-trien)][Mn(II)Cr(III)(ox)(3)]·CH(3)NO(2).0.5H(2)O (1) and [Fe(III)(5-CH(3)Osal(2)-trien)][Mn(II)Cr(III)(ox)(3)] (2) are reported. The structure of 1, that crystallizes in the P2(1) chiral space group, presents a 2D honeycomb anionic layer formed by Mn(II) and Cr(III) ions linked through oxalate ligands and a cationic layer of [Fe(III)(5-NO(2)sal(2)-trien)](+) complexes intercalated between the 2D oxalate network. The structure of 2, that crystallizes in the Pna2(1) acentric space group, presents a 3D achiral anionic network formed by Mn(II) and Cr(III) ions linked through oxalate ligands wit…
Formation of the Cationic [(2‐Aminoethenyl)carbine]iron Complexes by Treatment of (2‐Methoxyethenyl)carbene Complexes with Primary Amines:Synthesis a…
1997
Cationic (2-methoxyethenyl)methoxycarbene iron complexes 2, [Cp(CO)2Fe(C(OMe)CHCR(OMe))+][PF6−], are obtained by the addition of methanol to the corresponding (alkynyl)-methoxycarbene complexes 1, [Cp(CO)2Fe(C(OMe)CCR)+][PF6−]. Primary amines, H2NR', react with these 1,3-dimethoxy-substituted (alkenyl)carbene complexes, 2, through an addition/elimination process to yield cationic (2-aminoethenyl)methoxycarbene iron complexes, 3, [Cp(CO)2Fe(C(OMe)CHCR(NHR'))+][PF6−] in an isolated yield of 71–90%. The complexes 3a–c were characterized by X-ray structural analyses. Thus, previously isolated products, from the reaction, of the (alkynyl)methoxycarbene complexes 1a and 1c, with aniline at room t…
Novel route in the synthesis of MCM-41 containing framework aluminum and its characterization
1999
Abstract Mesoporous molecular sieve MCM-41 with incorporated structural aluminum (Al-MCM-41) was prepared by hydrolysis of a solution of tetraethoxysilane and aluminum isopropoxide in the presence of ammonia as a catalyst. This method provides Al-MCM-41 of different Si/Al ratios from 13 to 297 corresponding to 0.3–7 mol% Al within an hour. X-ray diffraction and nitrogen adsorption measurements showed that the Al-MCM-41 prepared by this method had a highly ordered structure of pore arrays. Most Al atoms in these samples were incorporated tetrahedrally in the MCM-41 structure, which gave rise to cationic sites in the framework.
Experimental and theoretical study using DFT method for the competitive adsorption of two cationic dyes from wastewaters
2016
Abstract The adsorption of cationic dyes, Basic Yellow (BY28) and Methylene Blue (MB) on a new activated carbon from medlar species were studied in both single and binary system. Some experimental parameters, namely, pH, amount of adsorbent and contact time are studied. Quantum chemical results indicate that the adsorption efficiency was directly related to the dye electrophilicity power. Some theorical parameters were calculated and proved that MB is more electrophilic than BY28, than greatest interaction with surface sites. Kinetic study showed that the adsorption follows the pseudo-second-order model and Freundlich was the best model to describe the phenomenon in the single and binary sy…
Neutral one-dimensional metal chains consisting of alternating anionic and cationic rhodium complexes.
2012
The metallophilic interactions were investigated within chains of oppositely charged rhodium carbonyl complexes. The cationic [Rh(CO)(2)(L)](+) (L = 2,2'-bipyridine and 1,10-phenanthroline) and anionic [RhCl(2)(CO)(2)](-) units were self-assembled into one dimensional rhodium chains supported by electrostatic interactions. The array of Rh centers in {[Rh(CO)(2)(2,2'-bpy)][RhCl(2)(CO)(2)]}(n) was found to be nearly linear with a Rh···Rh···Rh angle of 170.927(11)° and Rh···Rh distances of 3.3174(5) Å and 3.4116(5) Å. The crystal structure of {[Rh(CO)(2)(1,10-phen)][RhCl(2)(CO)(2)]} consisted of two sets of crystallographically independent chains with slightly different Rh···Rh···Rh angles (17…
Copper(I) Complexes of Bis(2-(diphenylphosphino)phenyl) Ether: Synthesis, Reactivity, and Theoretical Calculations
2007
The tricoordinated cationic Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(kappa(1)-P-DPEphos)][BF4] (1) (DPEphos = bis(2-(diphenylphosphino)phenyl) ether) containing a dangling phosphorus center was synthesized from the reaction of [Cu(CH3CN)(4)][BF4] with DPEphos in a 1:2 molar ratio in dichloromethane. When complex 1 is treated with MnO2, elemental sulfur, or selenium, the uncoordinated phosphorus atom undergoes oxidation to form a PE bond resulting in the formation of complexes of the type [Cu(kappa(2)-P,P'-DPEphos)(kappa(2)-P,E-DPEphos-E)][BF4] (2, E = O; 3, E = S; 4, E = Se) containing a Cu-E bond. The zigzag polymeric Cu-I complex [Cu(kappa(2)-P,P'-DPEphos)(mu-4,4'-bpy)](n)[BF4](n) (5) was …
Review: monoclinic zirconia, its surface sites and their interaction with carbon monoxide
2015
This review concerns monoclinic zirconia, its surface sites and their probing with carbon monoxide. The surface sites and their modifications using thermal treatments with vacuum or reactive gases are also included. In this work, we present information on the nature and manipulation of hydroxyl species and their quantities on the surface, the different types of cationic sites where CO is adsorbed linearly and their energetics, as well as the surface sites and dynamics of formate formation. We also compare the surface concentrations of the different surface species to better understand the extent and nature of the interactions. Finally, we discuss some of the remaining open questions and how…
Estimation of Solute-Stationary Phase and Solute-Mobile Phase Interactions in the Presence of Ionic Liquids
2019
The presence of free silanols on alkyl-bonded reversed-phase stationary phases is responsible for broad and asymmetrical peaks when basic drugs are chromatographed with conventional octadecylsilane (C18) columns due to ionic interactions. In the last few years, ionic liquids (ILs) have attracted attention to reduce this undesirable silanol activity. ILs should be considered as dual modifiers (with a cationic and anionic character), which means that both cations and anions are able to adsorb on the stationary phase, creating a positively or negatively charged layer, depending on the relative adsorption. The accessibility of basic compounds to the silanols is prevented by both the IL cation a…