One-pot synthesis of tripodal tris(2-aminoethyl)amine derivatives from seven molecular components

Complex tripodal tris(2-aminoethyl)amine (tren)-based ligands have been prepared in a single-pot reaction of tren with 3 equiv each of cyclohexenone and a benzaldehyde derivative (i.e., from seven components and three molecular types). The highest yield of product was obtained for p-nitrobenzaldehyde, the most electrophilic aldehyde used.     

Molecular symmetry and biological activities of new symmetrical tris(2-aminoethyl)amine derivatives

In terms of molecular symmetry and bioactivity, new C3- and CS-symmetrical derivatives based on the tris(2-aminoethyl)amine scaffold were designed and synthesized. The synthesized compounds were evaluated for antiviral activity with herpes simplex virus type 1 (HSV-1) by a plaque reduction assay and for cytotoxic activity with Vero cells. Most of the compounds showed no significant anti-HSV-1 activity, but some of the symmetrical derivatives showed high levels of cytotoxic activitiy.     

Encapsulating ruthenium and osmium with tris(2-aminoethyl)amine based tripodal ligands

The reaction of a series of tripodal ligands, H₃L^1,2 and L^3-6, with [M(PPh₃)₂Cl₂] (M = Ru, Os) affords a family of coordination cage compounds of the type [M^IIIL^1,2] (1-4) or [M^IIL^3-6](BPh₄)₂ (5-12). The Schiff base ligands (H₃L¹, L³, L⁵) have been synthesized by condensation of tris(2-aminoethyl)amine with salicylaldehyde, pyridine-2-aldehyde and 1-methyl-2-imidazolecarboxaldehyde. These ligands were further reduced and subsequently methylated to form the new ligands (H₃L², L⁴, L⁶). Single crystal X-ray diffraction studies of 1 and 2 show that the tripodal ligand wraps around the metal center as a hexadentate ligand to form a cage. All the synthesized compounds have been thoroughly characterized by ESI-MS, FT-IR, UV-Vis and NMR spectroscopic methods. To the best of our knowledge, this is the first ever report of osmium complexes with tris(2-aminoethyl)amine based tripodal ligands. DFT calculations were performed to obtain geometry optimized structures of all the other complexes (3-12).     

Synthesis and crystal structure of an imidazolate-bridged dicopper tris(2-aminoethyl)amine complex

The [Cu(tren)(Im)Cu(tren)](ClO4)3·MeCN complex [tren=tris(2-aminoethyl)amine; Im=imidazolate anion] has been synthesized and characterized spectrally. The X-ray crystal structure analysis reveals that the imidazolate anion serves as a bridge to form a noncentrosymmetric dimeric structure in the complex. The co-ordination geometry about each copper(II) ion is a distorted trigonal bipyramid with three primary amine groups of the tren ligand forming the equatorial plane. The tertiary amine group and the imidazolate anion are in the axial positions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis of gold nanoparticles stabilized with di-(2-ethylhexyl)dithiophosphoric acid and tris(2-aminoethyl)amine

Methods for preparing gold nanoparticles (NPs) surface-stabilized with di-(2-ethylhexyl)dithiophosphoric acid (DTPA) and tris(2-aminoethyl)amine (TAEA), which endow the nanoparticles with hydrophobic and hydrophilic properties, are described. In the case of DTPA, Au-NPs are first synthesized with surfactant shells by means of reducing [AuCl₄]^? with hydrazine in inverted micelles of oxyethylated Triton N-42 in a low-polarity medium of decane; then, the micelles are destroyed by polar chloroform in the presence of DTPA, which has a great affinity to gold due to its sulfur donor atoms and substitutes for the surfactant on the surface of the nanoparticles. In preparing hydrophilic nanoparticles, [AuCl₄]^? is reduced with solid NaBH₄ directly in a nonaqueous solution of TAEA based on an ethanol and 2-propanol (3: 10) mixture. The nanoparticles are characterized by elemental analysis (for Au, C, H, N, and Na), X-ray powder diffraction, electronic absorption spectra, IR spectra, photon-correlation spectra, and transmission electron microscopy (TEM).     

Star-shaped azomethines based on tris(2-aminoethyl)amine. Characterization,thermal and optical study

The synthesis and detailed (physico)-chemical (¹H/¹³C NMR, FTIR, UV–vis and elemental analysis) characterizations of new star-shaped compounds based on tris(2-aminoethyl)amine, including in their structure an azomethine function (HCN–) and alkoxysemiperfluorinated (–O–(CH₂)₃–(CF₂)₇–CF₃), octadecyloxy aliphatic (–O–(CH₂)₁₇–CH₃) chain or two phenyl rings (–Ph–Ph–) as a terminal group, were reported. The mesomorphic behavior was investigated by means of differential scanning calorimetry (DSC), polarized optical microscopy (POM) and additionally by FTIR(T) and UV–vis(T) spectroscopy. Wide-angle X-ray diffraction (WAXD) technique was used to probe the structural properties of the azomethines. Moreover, the azomethine A1 was electro-spun to prepare fibers with poly(methyl methacrylate) (PMMA) and investigated by DSC and POM. Additionally, a film of the A1 with PMMA was cast from chloroform and the thermal properties of the film were compared with the thermal properties of the fiber and powder. It was showed that terminal groups dramatically influence the thermal and optical properties of the star-shaped azomethines.     

Solid-phase extraction of lead(II) ions using multiwalled carbon nanotubes grafted with tris(2-aminoethyl)amine

Multiwalled carbon nanotubes were grafted with tris(2-aminoethyl)amine (MWCNTs-TAA) and employed for solid phase extraction and preconcentration of trace lead ions prior to its determination by inductively coupled plasma optical emission spectrometry. The material was characterized by FT-IR and Raman spectroscopy, thermosgravimetric and elemental analysis. The effects of pH value, shaking time, sample volume, elution conditions and potentially interfering ions were investigated. Under the optimum conditions, the maximum adsorption capacity is 38?mg?g^?1 of Pb(II), the detection limit is 0.32?ng?mL^?1, the enrichment factor is 60, and the relative standard deviation is 3.5% (n?=?6). The method has been applied to the preconcentration of trace amounts of Pb(II) in environmental water samples with satisfactory results.

Synthesis of homochiral tris(2-alkyl-2-aminoethyl)amine derivatives from chiral alpha-amino aldehydes and their application in the synthesis of water soluble chelators

A novel synthesis of 3-fold symmetric, homochiral tris(2-alkyl-2-aminoethyl)amine (TREN) derivatives is presented. The synthesis is general in scope, starting from readily prepared chiral alpha-amino aldehydes. The optical purity of the N-BOC protected derivatives of tris(2-methyl-2-aminoethyl)amine and tris(2-hydroxymethyl-2-aminoethyl)amine has been ascertained by polarimetry and chiral NMR chemical shift experiments. An X-ray diffraction study of the L-alanine derivative (tris(2-methyl-2-aminoethyl)amine.3 HCl, L-Ala(3)-TREN) is presented: crystals grown from ether diffusion into methanol are cubic, space group P2(1)3 with unit cell dimensions a = 11.4807(2) A, V = 1513.23(4) A(3), and Z = 4. Attachment of the triserine derived backbone tris(2-hydroxymethyl-2-aminoethyl)amine (L-Ser(3)-TREN) to three 3-hydroxy-1-methyl-2(1H)-pyridinonate (3,2-HOPO) moieties, followed by complexation with Gd(III) gives the complex Gd(L-Ser(3)-TREN-Me-3,2-HOPO)(H(2)O)(2), which is more water soluble than the parent Gd(TREN-Me-3,2-HOPO)(H(2)O)(2) and a promising candidate for magnetic resonance imaging (MRI) applications. Crystals of the chiral ferric complex Fe(L-Ser(3)-TREN-Me-3,2-HOPO) grown from ether/methanol are orthorhombic, space group P2(1)2(1)2(1), with unit cell dimensions a = 13.6290(2) A, b = 18.6117(3) A, c = 30.6789(3) A, V = 7782.0(2) A(3), and Z = 8. The solution conformation of the ferric complex has been investigated by circular dichroism spectroscopy. The coordination chemistry of this new ligand and its iron(III) and gadolinium(III) complexes has been studied by potentiometric and spectrophotometric methods. Compared to the protonation constants of previously studied polydentate 3,2-HOPO-4-carboxamide ligands, the sum of protonation constants (log beta(014)) of L-Ser(3)-TREN-Me-3,2-HOPO (24.78) is more acidic by 1.13 log units than the parent TREN-Me-3,2-HOPO. The formation constants for the iron(III) and gadolinium(III) complexes have been evaluated by spectrophotometric pH titration to be (log K) 26.3(1) and 17.2(2), respectively.     

Synthesis and crystal structure of a copper(II) complex of the tripodal tetradentate ligand tris(2-benzimidazolylmethyl)amine

A mononuclear copper complex [Cu(NTB)Cl]Cl·3CH₃CH₂OH (1) (NTB?=?tris(2-benzimidazolylmethyl)amine) was synthesized and its structure was determined by single crystal X-ray diffraction. In this complex, copper(II) is five-coordinate with NTB serving as a neutral tetradentate ligand. Three tertiary nitrogen atoms of benzimidazole groups of NTB formed the base of the trigonal bipyramidal geometry. One axial position was occupied by the apical nitrogen atom of NTB and the other was occupied by chloride. The ESR spectrum of complex 1 in ethanol at 101?K was recorded and the well-defined ESR parameters (g _∥?=?2.02, g _⊥ =?2.16 and A _∥ ^?=?109?G) indicated that the Cu(II) has a distorted trigonal-bipyramidal environment, in good agreement with crystal structure determination for complex 1.     

Synthesis, characterization and crystal structure of a tris(2-aminoethyl)amine copper complex with a imidazole coligand

Summary The complex [Cu(tren)ImH](ClO₄)₂ [tren = tris(2-aminoethyl) amine, ImH = imidazole] has been synthesized and characterized by elemental analyses, conductivity measurements, magnetic moments, and electronic, i.r., e.s.r. and XPS spectral studies. The X-ray crystal structure reveals that there are two kinds of cation [Cu(tren)(ImH)]²⁺ in the crystal, cations A and B, in a 21 ratio, respectively; so the stoichiometric formula is [Cu(tren)(ImH)]_1.5(ClO₄)₃. Cation B is disordered. The Cu^II ions in both cations A and B are in a trigonal bipyramidal geometry with the three primary amine groups of the tren ligand forming the equatorial plane, and the tertiary amine group and the imidazole ligand in apical positions.     

Tris-(2-aminoethyl)amine-based tripodal trisindolylureas: new receptors for sulphate

A series of tren-based amide or urea linked tris-indole anion receptors have been synthesised and their anion complexation properties studied in DMSO-d ₆/water mixtures.     

Selective anion sensing by a ruthenium(II)-bipyridyl-functionalized tripodal tris(urea) receptor

A tripodal tris(urea) ligand with 2,2'-bipyridyl (bpy) substituents (L) has been designed and synthesized, which coordinates with three equivalents of Ru(bpy)(2)Cl(2)·2H(2)O, followed by treatment with NH(4)PF(6), to afford the anion receptor [(bpy)(6)Ru(3)L](PF(6))(6) (1). The anion-binding behavior of the ligand L and the Ru(II)-bpy functionalized receptor 1 toward different anions was investigated by (1)H NMR (for L and 1), fluorescence, and UV-vis spectroscopy (for 1). Both compounds showed selective recognition of SO(4)(2-) or H(2)PO(4)(-) ions in the 1:1 binding mode in the NMR studies. The Ru(II) complex 1 displayed the metal-to-ligand charge transfer emission at 600 nm, which was quenched on addition of the sulfate and dihydrogen phosphate ions. Quantitative fluorescence titration experiments were carried out and the stability constants (log K) of the complex 1 with SO(4)(2-) and H(2)PO(4)(-) ions were obtained to be 4.73 and 4.69 M(-1) (1:1 binding mode), respectively.     

Reaction of tetrafluorosilane with tris(2-hydroxyethyl)amine, tris(2-trimethylsiloxyethyl)amine and bis(2-trimethylsiloxyethyl)amine and its N-methyl derivative. 1,1-difluoroquasisilatranes

Reaction of tetrafluorosilane with tris(2-hydroxyethyl)-and tris(2-trimethylsiloxyethyl)amine results in formation of 1-fluorosilatrane and fluorosilatrane in 75 and 53% yield, respectively. Reaction of tetrafluorosilane with bis(2-trimethylsiloxyethyl)amine and its N-methyl derivative leads to the hitherto unknown 1,1-difluoroquasisilatranes (N → Si) F₂Si(OCH₂CH₂)₂NR (R = H, Me) containing donor-acceptor bond N → Si and pentacoordinate silicon atom. The structure of the synthesized compounds was proved by ¹H, ¹³C, ¹⁵N, ¹⁹F, ²⁹Si NMR and IR spectroscopy.     

Mononuclear oxovanadium complexes of tris(2-pyridylmethyl)amine

Mononuclear oxovanadium(IV) and dioxovanadium(V) complexes of tris(2-pyridylmethyl)amine (tpa) have been prepared for the first time. Crystal structure determinations of three oxovanadium(IV) complexes, [VO(SO4)(tpa)], [VOCl(tpa)]PF6, or [VOBr(tpa)]PF6, and a dioxovanadium(v) complex [V(O)2(tpa)]PF6 disclosed that the tertiary nitrogen of the tpa ligand always occupies the trans-to-oxo site. The structures of an oxo-peroxo complex [VO(O2)(tpa)]Cl that was prepared previously and of a mu-oxo vanadium(III) complex [{VCl(tpa)}2(mu-O)](PF6)2 have also been determined. The tertiary nitrogen is located at a trans site to the peroxo and chloride ligands, respectively. The total sums of the four V-N bond lengths from the tpa ligand are remarkably similar among the six complexes, indicating that the vanadium oxidation states become less influential in tpa bonding due primarily to the coordination of electron-donating oxo ligand(s). Absorption spectra of [VOCl(tpa)]+ in acetonitrile showed a significant change upon addition of p-toluenesulfonic acid and HClO4, but not on addition of benzoic acid. Protonation at the oxo ligand by the former two acids is suggested. Cyclic voltammetric studies in acetonitrile verified the proton-coupled redox behavior of the V(III)/V(IV) process involving the oxo ligand for the first time. From the dependence of the added p-toluenesulfonic acid to the CV, redox potentials for the following species have been estimated: [V(IV)OCl(tpa)]+/[V(III)OCl(tpa)](E1/2=-1.59 V vs. Fc+/Fc), [V(IV)(OH)Cl(tpa)]2+/[V(III)(OH)Cl(tpa)]+(Epc=-1.34 V), [V(IV)(OH2)Cl(tpa)]3+/[V(III)(OH2)Cl(tpa)]2+(Epa=-0.49 V), and [V(IV)Cl2(tpa)]2+/[V(III)Cl2(tpa)]+(E1/2=-0.89 V). The reduction of [V(V)(O)2(tpa)]+ in 0.05 M [(n-Bu)4N]PF6 acetonitrile showed a major irreversible reduction wave V(V)/(IV) at -1.48 V. The metal reduction potentials of the oxovanadium(IV) and dioxovanadium(V) species are very close, reinforcing the significant influence of the oxo ligand(s).     

A monomolecularly imprinted dendrimer (MID) capable of selective binding with a tris(2-aminoethyl)amine guest through multiple functional group interactions

A molecularly imprinted dendrimer (MID) with a colorimetric reporter group exhibits three-point binding of tris(aminoethyl)amine in THF with a K(assoc)= 3.3 x 10(6) M(-1).