Tetramethylmalonamide Research Articles

Structural Trends and Vibrational Analysis of N,N,N′,N′−Tetramethylmalonamide Complexes Across the Lanthanide Series

AbstractFundamental understanding of coordination chemistry across the lanthanide series is essential for explaining chemical behavior of rare‐earth metals in complex liquid‐liquid extraction processes, which in turn affects the distribution ratios and efficacy of separations as a whole. In this work, we explore the structural trends between the lanthanides and a neutral N,N,N′,N′−tetramethylmalonamide (TMMA) ligand within four isolated families of solid‐state compounds: Ln(trans‐TMMA)2(NO3)3 Ln=La−Nd, Sm; Ln(cis‐TMMA)2(NO3)3 Ln=Eu−Tb, Er; [Ln(TMMA)3(NO3)2][Ln(TMMA)(NO3)4] Ln=Dy−Tm; Ln(Κ2‐TMMA)(iPrOH)(NO3)3 and Ln(Κ1‐TMMA)(Κ2‐TMMA)(NO3)3 Ln=Yb, Lu. Moving across the lanthanide series, we note the formation of both discrete charge‐neutral complexes, as well as charged molecular anion‐cation pairs, with variations in spatial ligand arrangement, coordination numbers, and ligand denticities. IR and Raman spectroscopy paired with DFT frequency calculations were used for an in‐depth investigation of vibrational modes unique to each structural family. The collection of isolated model compounds was also discussed in the context of liquid‐liquid separations based on reported distribution ratios from malonamide extraction.

Synthesis of diamide-based resin for selective separation of 99Tc

N,N,N′,N′-tetramethylmalonamide (TMMA) has been successfully grafted onto the chloroacetylated poly(styrene-co-divinylbenzene) resin to obtain a novel diamide-based resin (PS–TMMA). PS–TMMA exhibited high adsorption capacity and selectivity toward TcO4− in 0.1–1 M HCl. The adsorption process of PS–TMMA conforms (Revise: conformed) to Langmuir isotherm and pseudo-second-order kinetics model. The results of column experiments revealed TcO4− can be completely separated from the coexisting fission products (Sr(II), Eu(III), Dy(III), and 1 M NH3·H2O can re-collect TcO4− absorbed in the resin column. The adsorption mechanism of TcO4− is considered that PS–TMMA is converted into anion exchange resin in acidic condition.

Extraction of tetravalent uranium by N,N,N',N'-tetramethylmalonamide in ionic liquid

In this paper, the extractant N,N,N',N'-tetramethylmalonamide (TMMA) was used to extract tetravalent uranium (abbreviated as U(IV)) from aqueous nitric acid solution into ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][NTf2]) system. It is found that the distribution coefficient of U(IV) in [C4mim][NTf2] is improved to 23, and the single stage extraction efficiency is more than 95% at 1:1 vol phase ratio, compared with the traditional toluene system. While U(VI) could be hardly extracted from nitric acid solutions at a concentration between 1.0 and 3.0 M, U(IV) and U(VI) could be selectively separated in this system and separation factor (SFIV/VI) could reach 28. According to the slope analysis, each U(IV) ion probably bounds one TMMA molecule. For nitric acid at a concentration between 1.0 and 3.0 M, the extraction process of U(IV) might follow the cation exchange mechanism. It is also found that the U(IV) complex extracted into the ionic liquid phase could be very stable and maintain in the air for at least two weeks without being oxidized.

Polymer-supported urea: The effect of hydrogen bonding on lanthanide ion affinities

Hydrogen bonding has been proposed as the triggering mechanism for the sorption of lanthanide ions by polymer-supported tetramethylmalonamide (TMMA) and diethylenetriamine (DETA) – substituted malonate ester. In the current study, DETA was immobilized onto cross-linked poly(vinylbenzyl chloride), converted to the urea, and its affinity determined for lanthanide ions from solutions of 2–8M HCl. Lanthanide affinities significantly increase when the acid concentration exceeds 4M. The site at which sorption occurs forms after protonation of the carbonyl, stabilization by hydrogen bonding to the interior nitrogen and resultant formation of an iminium ion. This is consistent with the mechanism proposed for the amide polymers. TMMA has the weakest affinities for Ln(III) ions yet is most selective due to attenuation of the (+) charge at the iminium site by two electron-donating methyl groups (=NR2(+)); DETA-malonamide (MAm) has higher Ln(III) affinities than TMMA but is less selective because the iminium has only one –CH2- moiety attenuating the (+) charge (=NHR(+)); the urea also forms a secondary iminium but its higher basicity makes its iminium more positively charged than that in DETA–MAm and therefore a stronger ligand. The urea has the highest affinities and is unique in having the lanthanide distribution coefficients correlate with the sum of the first, second and third ionization energies. The implication of this for the sorption mechanism is discussed.

Mechanism of Ionic Recognition by Polymer-Supported Reagents: Immobilized Tetramethylmalonamide and the Complexation of Lanthanide Ions

The mechanism of ionic recognition by polymer-supported reagents is probed with cross-linked polystyrene modified with tetramethylmalonamide (TMMA) ligands. The substrates are lanthanide ions in 0.001-8 M HCl and HNO(3) solutions. The results fall into three regions of acid concentration: low, mid, and high. In HCl, distribution coefficients are low in 0.001 to 2 M, increase in 4 and 6 M, and then decrease in 8 M HCl. In the low-acid region, the metal ion remains with its waters of hydration and does not coordinate to the carbonyl oxygens. As the acid concentration exceeds 2 M, protonation of the amide occurs to form an iminium moiety, electrostatically attracting the anionic lanthanide complex through ion-exchange and releasing waters of hydration. At high acid concentration, the apparent affinity decreases due to competition by the large excess of chloride ions for the ion-exchange sites. The affinity sequence in 6 M HCl is Tb > Dy > Eu > Gd > Ho > Sm > Er > Tm > Yb > Lu > Nd > Ce > La. The TMMA-Ln interaction is due to recognition since there is a point of maximum affinity across the series rather than a monotonic trend. The trends are comparable in HNO(3). A comparison of the distribution coefficients at the maxima (6 M HCl and 4 M HNO(3)) shows nitrate to have greater values than chloride due to a hydration effect, as also indicated by results from H(2)SO(4).

Malonamide-Functionalized Gold Nanoparticles for Selective, Colorimetric Sensing of Trivalent Lanthanide Ions

A selective and sensitive molecular sensor for trivalent lanthanide (Ln(3+)) ions based upon a malonamide-functionalized gold nanoparticle was developed for colorimetric detection in water. A new synthetic approach permits nanoparticle synthesis, stabilization, and incorporation of a selective lanthanide binding site in a single, direct step. The design incorporates a specifically tailored dual function precursor ligand that bears a sodium thiosulfate (Bunte salt) group that links to the gold nanoparticle core and a tetramethylmalonamide (TMMA) group that serves as a selective Ln(3+) binding site. The sensor's colorimetric response to lanthanide ions is immediate, and it is sensitive down to approximately 50 nM for Eu(3+) and Sm(3+). This study demonstrates a general strategy for direct, convenient nanoparticle synthesis that enables the incorporation of analyte binding groups directly to the nanoparticle surface, allowing colorimetric sensors to be developed for widespread use. The one-step synthesis offers uniform surface ligand composition, reduces the volume of waste generated during nanoparticle synthesis and purification, produces functionalized gold nanoparticles that are stable in nonmodified aqueous environments, and offers colorimetric detection at ambient temperature.

Structural development Of TMMA and SSQXN‐8 as porous chelating resins

AbstractSuperfast kinetics of Nd+3, Eu+3, and Gd+3 ions were studied on the surfaces of N,N,N\,N\‐tetramethylmalonamide (TMMA) and silsesquioxane (SSQXN‐8) resins. TMMA and SSQXN‐8 were prepared by suspension polymerization and sol–gel routes, respectively. They were identified using elemental analysis, FTIR, H‐NMR, 13C‐NMR, MIP, and BET surface area. Kinetic investigations were performed in batch conditions and different models were used to fit the data; Boyd and Helfferich models were found the best. The diffusion of the ions through the resins were very fast and found to be in the order of 10−16 m2/S. Effective diffusions of the studied ions were found to be 10−15 order of magnitude and directly proportional to the kinetic energy of the transition state. ΔS* values from −166.044 to −179.297 J mol−1 K−1 were estimated as entropy stability factors of the system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Variation of single wall carbon nanotube dispersion properties with alkyl amide and halogenated aromatic solvents

Organic solvents from the alkyl amide and halogenated aromatic classes have been analyzed as dispersion agents for high purity single wall carbon nanotubes (SWCNTs). The resulting dispersions from two novel SWCNT solvents, N,N,N′,N′-tetramethylmalonamide (TMMA) and 1-chloronaphthalene (1-CLN), have been compared to the well-established solvents, N,N-dimethylacetamide (DMA) and 1,2-dichlorobenzene (DCB). Optical absorption spectroscopy on a series of high purity SWCNT concentrations was used to obtain solvent-dependent dispersion limits, extinction coefficients, and dispersion stability. The variation in SWCNT optoelectronic properties was measured for each solvent dispersion as a function of ultrasonication time and the results demonstrate that under conventional ultrasonication times the halogenated aromatic solvents (DCB and 1-CLN) can significantly affect the SWCNT optical absorption. A post-dispersion analysis was performed on samples, after removal of the solvents, by Raman spectroscopy to monitor structural changes in the SWCNTs. The spectroscopy results for the halogenated aromatic solvents are consistent with formation of a sonopolymer and subsequent interaction with the SWCNTs. In comparison, the alkyl amide solvents (DMA and TMMA) show similar dispersion limits with no significant change in absorbance as a function of ultrasonication, and can easily be removed without affecting the SWCNTs.

Electrochemical and spectroscopic investigations of uranium(III) with N, N, N′, N′-tetramethylmalonamide in DMF

In order to investigate the electrode reaction of negative electrolyte, U(III)/U(IV), of the all-uranium redox-flow battery proposed by us, we investigated the magnetic susceptibility, spectroscopy and electrode reactions of U(III) and U(IV) complexes with N, N, N′, N′-tetramethylmalonamide (TMMA). The effective magnetic moment for the U(III) complex (1.95 μ B/atomU) is significantly smaller than the theoretical moment for free U 3+ ion, and this may indicate the itinerant nature of U(III) due to the coordination of TMMA. In N, N-dimethylformamide (DMF), the energy levels due to f–f transitions was only slightly perturbed from those of uranium(III) perchlorate in DMF. The U(III)/U(IV) redox potential of U(III)-TMMA complex shifted negatively from that of uranium(III) perchlorate.

Bicyclic and Acyclic Diamides: Comparison of Their Aqueous Phase Binding Constants with Nd(III), Am(III), Pu(IV), Np(V), Pu(VI), and U(VI)

This report describes affinity measurements for two, water-soluble, methyl-alkylated diamides incorporating the malonamide functionality, N,N,N',N' tetramethylmalonamide (TMMA) and a bicyclic diamide (1a), toward actinide metal cations (An) in acidic nitrate solutions. Ligand complexation to actinides possessing oxidation states ranging from +3 to +6 was monitored through optical absorbance spectroscopy, and formation constants were obtained from the refinement of the spectrophotometric titration data sets. Species analysis gives evidence for the formation of 1, 4, 1, and 2 spectrophotometrically observable complexes by TMMA to An(III, IV, V, and VI), respectively, while for 1a, the respective numbers are 3, 4, 2, and 2. Consistent with the preorganization of 1a toward actinide binding, a significant difference is found in the magnitudes of their respective formation constants at each complexation step. It has been found that the binding affinity for TMMA follows the well-established order An(V) < An(III) < An(VI) < An(IV). However, with 1a, Np(V) forms stronger complexes than Am(III). The complexation of 1a with Np(V) and Pu(VI) at an acidity of 1.0 M is followed by reduction to Np(IV) and Pu(IV), whereas TMMA does not perturb the initial oxidation state for these dioxocations. These measurements of diamide binding affinity mark the first time single-component optical absorbance spectra have been reported for a span of actinide-diamide complexes covering all common oxidation states in aqueous solution.

Effect of pore diameter of TMMA chelating resin beads on the adsorption properties of U(VI) and Ce(III) from different media

In order to investigate the relationship between the pore diameter and the rate of uptake of U(VI) ions and Ce(III) ions, N ,N ,N ?,N ?-tetramethylmalonamide (TMMA) chelating resins with different pore diameters were synthesized, using different pore producing solvents. The batch technique was used to study the kinetics of the adsorption U(VI) and Ce(III) ions from 3 M HNO3, acid, and 3 M NaNO3� /0.05 M HNO3, salt, media. The process was found to be controlled by the particle diffusion model. The calculated values for the diffusion coefficient were found to be directly proportional to the pore diameter, i.e. the resin with the largest pore diameter showed the fastest rate of uptake. # 2002 Elsevier Science B.V. All rights reserved.

The Utilization of TMMA Chelating Resin for the Adsorption of U(VI) and Some Lanthanide Ions from Acidic Media

N,N,N ′,N ′‐Tetramethylmalonamide (TMMA) chelating resin was used for the separation of U(VI) ions and some rare earth ions from acidic media. Effect of nitric acid concentration on the distribution coefficient, in the acid concentration range 0.05–6 M, is presented. The equilibrium isotherms of U(VI) ions, Ce(III), Eu(III), Nd(III), and Dy(III) were investigated. The utilization of the resin for the removal U(VI) ions and Ce(III) ions on laboratory‐scale fixed‐bed column was studied. The elution of the sorbed ions by 0.1 M HNO3 was found to be possible. The column‐operation results proved that the resin is more promising compared with dihexyl‐N,N‐diethylcarbamoylmethyl‐phosphonate (CMP) chelating resin.

Complexation of Eu(III) with alkyl-substituted malonamides in acetonitrile

The complexation of Eu(III) with a series of alkyl-substituted malonamide ligands was studied in organic solvents using calorimetry, FT-IR and luminescence spectroscopy. The formation constants were determined in acetonitrile containing small amounts of dimethyl sulfoxide. The effects of substitution on the nitrogen atoms as well as on the central carbon atom were evaluated. For the substitution on the nitrogen atoms, the formation constants decrease in the order: N,N,N′,N′-tetramethylmalonamide (TMMA) > N,N′-dibutyl-N,N′-dimethylmalonamide (DMDBMA) > N,N,N′,N′-tetrahexylmalonamide (THMA) > N,N,N′,N′-tetraisopropylmalonamide (TiPMA). For substitution on the central carbon atom, the formation constants decrease in the order: N,N,N′,N′-tetrahexyl-2-methylmalonamide (MeTHMA) > N,N,N′,N′-tetrahexylmalonamide (THMA) > N,N,N′,N′-tetrahexyl-2,2-dimethylmalonamide (DMeTHMA). These orders are discussed in terms of the steric effect and the ligand basicity.

Calorimetric and spectroscopic studies of Eu(III) complexation with tetramethylmalonamide and tetramethylsuccinamide in acetonitrile and dimethylsulfoxide

The complexation of Eu(III) with two N, N, N′, N′-alkyl-substituted diamide ligands, tetramethylmalonamide (TMMA) and tetramethylsuccinamide (TMSA), was studied in organic solvents using titration calorimetry, FT IR and luminescence spectroscopy. The formation constants and enthalpy changes of the complexation were determined in pure acetonitrile and in acetonitrile containing small amounts of dimethyl sulfoxide (DMSO). It was observed that TMMA forms stronger complexes with Eu(III) than TMSA in the latter systems, which is attributed to the structural difference between TMMA and TMSA and an entropy effect. The effect of Eu(III) solvation by DMSO on the formation of the Eu(III)–diamide complexes is also discussed.

N, N, N', N'-Tetramethylmalonamide adducts of lanthanide trifluoromethanesulphonates

Adducts of lanthanide trifluoromethanesulphonates and N, N, Nl, N'-tetramethylmalonamide (TMMA) with the compositions Ln(CF 3SO 3) 3·5TMMA (Ln  La, Ce) and Ln(CF 3SO 3) 3·4TMMA (Ln  Pr-Lu, Y) were prepared and characterized. These compounds behave as 1:3 electrolytes in nitromethane and acetonitrile. Conductance and IR data indicate that the anions are not coordinated to the central ions. The ν(CO) and ν(CN) frequencies of the ligand were interpreted in terms of coordination through the carbonyl oxygens. Four series of X-ray patterns were detected: 1. (a) lanthanum and cerium; 2. (b) neodymium and europium; 3. (c) praseodymium, samarium, gadolinium to ytterbium and yttrium; 4. (d) lutetium. The absorption spectra of the praseodymium, neodymium, holmium and erbium adducts were investigated in the solid state and in nitromethane solutions. The emission spectra of the europium adduct and the europium-doped lanthanum and lutetium adducts were determined and will be discussed.

Lanthanide iodide adducts of N,N,N′,N′-tetramethylmalonamide (TMMA)

Lanthanide iodide adducts of N,N,N′,N′-tetramethylmalonamide (TMMA)

Adducts between some lanthanide nitrates and perchlorates and N,N,N′,N′-tetramethylmalonamide(TMMA)

Addition compounds of N,N,N′,N′-tetramethylmalonamide (TMMA) and some lanthanide nitrates and perchlorates were obtained. Compounds of general formula Ln(NO 3) 3·2TMMA and Ln(ClO 4) 3·4TMMA (Ln  La, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) are described. The compounds were characterized by elemental analysis, i.r. spectra and X-ray powder patterns. The molar conductances in nitromethane were also determined.

Complexes of uranyl chloride and thorium and uranium tetrachlorides with dicarboxylic acid amides

NNN′N′-Tetramethyl-malonamide (TMMA), -αα-dimethylmalonamide (HMMA), -glutaramide (TMGA), and -3,3-dimethylglutaramide (HMGA) complexes with uranyl chloride and with thorium and uranium tetrachloride have been prepared in acetone. These have the compositions UO2Cl2,1·5TMMA (or TMGA), UO2Cl2,HMMA (or HMGA), ThCl4,2TMMA, ThCl4,1·5TMGA (HMMA or HMGA), UCl4,1·5TMMA (TMGA or HMGA), and UCl4,HMMA. Some chemical and physical properties of the complexes are reported.