Search Results (24)

Heterobimetallic complexes of an ambidentate deferiprone derivative, 3-hydroxy-2-methyl-1-(3-((pyridin-2-ylmethyl)amino)propyl)pyridin-4(1H)-one (PyPropHpH), incorporating an octahedral [Co(4N)]³⁺ (4N = tris(2-aminoethyl)amine (tren) or tris(2-pyridylmethyl)amine (tpa)) and a half-sandwich type [(η⁶-p-cym)Ru]²⁺ (p-cym = p-cymene) entity have been synthesized and characterized by various analytical techniques. The reaction between PyPropHpH and [Co(4N)Cl]Cl₂ resulted in the exclusive (O,O) coordination of the ligand to Co(III) yielding [Co(tren)PyPropHp](PF₆)₂ (1) and [Co(tpa)PyPropHp](PF₆)₂ (2). This binding mode was further supported by the molecular structure of [Co(tpa)PyPropHp]₂(ClO₄)₃(OH)·6H₂O (5) and [Co(tren)PyPropHpH]Cl(PF₆)₂·2H₂O·C₂H₅OH (6), respectively, obtained via the slow evaporation of the appropriate reaction mixtures and analyzed using X-ray crystallography. Subsequent treatment of 1 or 2 with [Ru(η⁶-p-cym)Cl₂]₂ in a one-pot reaction afforded the corresponding heterobimetallic complexes, [Co(tren)PyPropHp(η⁶-p-cym)RuCl](PF₆)₃ (3) and [Co(tpa)PyPropHp(η⁶-p-cym)RuCl](PF₆)₃ (4), in which the piano-stool Ru core is coordinated by the (N,N) chelating set of the ligand. Cyclic voltammetric measurements revealed that the tpa complexes can be reduced at less negative potentials, suggesting their capability to be bioreductively activated under hypoxia (1% O₂). Hypoxia activation of 2 and 4 was demonstrated by cytotoxicity studies on the MCF-7 human breast cancer cell line. PyPropHpH was shown to be a typical iron-chelating anticancer agent, raising the mRNA levels of TfR1, Ndrg1 and p21. Further qRT-PCR studies provided unambiguous evidence for the bioreduction of 2 after 72 h incubation under hypoxia, in which the characteristic gene induction profile caused by the liberated iron-sequestering PyPropHpH was observed. Full article

In this work, energetic coordination compounds (ECCs) of transition metals (Fe, Ni, Cu, Zn) containing aliphatic amines as ligands were synthesized: ethylenediamine; 1,3-diaminopropane; tris(2-aminoethyl)amine; tris(3-aminopropyl)amine. The compounds were investigated in terms of ignition/explosion temperature, friction and impact sensitivity. For selected compounds, structural characterisation was presented (IR-ATR spectroscopy, Raman spectroscopy) and their morphology was determined (SEM, powder XRD). They were also investigated by differential scanning calorimetry (DSC). In order to assess the potential application of selected ECCs in detonators, underwater explosion tests were carried out, determining energetic performance. The results achieved for detonators containing ECCs were compared with those for reference detonators (containing pentaerythritol tetranitrate, PETN), indicating their potential use as a “green” alternative to nitric acid esters. Full article

Copper (Cu) is a critical element for cancer cell proliferation and considerably accumulates in the nucleus. ⁶⁴Cu²⁺ is an anticancer radiopharmaceutical that targets the copper requirement of cancer cells. However, intravenously injected ⁶⁴Cu²⁺ ions primarily accumulate in the liver. Ligand complexation of ⁶⁴Cu²⁺ may be a promising method for increasing tumor delivery by reducing liver uptake. In this study, we used three tripodal amine ligands [tris(2-aminoethyl)amine (Tren), diethylenetriamine (Dien), and tris(2-pyridylmethyl)amine (TPMA)] to enclose ⁶⁴Cu²⁺ ions and compared their in vivo tumor and liver uptakes using a tumor-bearing xenograft mouse model of the extrahepatic bile duct carcinoma cell line TFK-1. We examined intracellular Cu distribution using microparticle-induced X-ray emission (micro-PIXE) analysis of these compounds. ⁶⁴Cu²⁺-Tren and ⁶⁴Cu²⁺-Dien showed higher tumor uptake than ⁶⁴Cu²⁺-TPMA and ⁶⁴Cu²⁺ ions in TFK-1 tumors. Among the three ⁶⁴Cu²⁺ complexes and ⁶⁴Cu²⁺ ions, liver uptake was inversely correlated with tumor uptake. Micro-PIXE analysis showed that in vitro cellular uptake was similar to in vivo tumor uptake, and nuclear delivery was the highest for ⁶⁴Cu²⁺-Tren. Conclusively, an inverse correlation between tumor and liver uptake was observed using three ⁶⁴Cu²⁺ complexes of tripodal amine ligands and ⁶⁴Cu²⁺ ions. These results provide useful information for the future development of anticancer ⁶⁴Cu radiopharmaceuticals. Full article

Zeolite NaP1 was found to display the highest affinity for CO₂ in preliminary modifications of coal fly ash-derived zeolites (4A, Y, NaP1 and X) by four amines (1,3-diaminopropane, N,N,N′,N′-tetramethylethylenediamine, Tris(2-aminoethyl)amine and ethylenediamine). In the second step, different fatty acid loaded NaP1 samples were prepared using palmitic, oleic and lauric acids. CO₂ and H₂O thermal programmed desorption (TPD) revealed changes in intrinsic basicity and hydrophilic character, expressed in terms of CO₂ and H₂O retention capacity (CRC and WRC, respectively). Infrared spectroscopy (IR), N₂ adsorption-desorption isotherms and scanning electron microscopy allowed for correlating these changes with the type of interactions between the incorporated species and the zeolite surface. The highest CRC values and the lowest CO₂ desorption temperatures were registered for NaP1 with the optimum content in palmitic acid (PA) and were explained in terms of the shading effect of surface acidity by the rise of basic Na⁺-palmitate salt upon cation exchange. The amine/fatty acid combination was found to paradoxically mitigate this beneficial effect of PA incorporation. These results are of great interest because they demonstrate that fatty acid incorporation is an interesting strategy for reversible CO₂ capture. Full article

Condensed tannin copolymerized with hyperbranched tris(2-aminoethyl)amine-urea formed by amine-amido deamination yields a particleboard thermosetting adhesive without any aldehydes satisfying the requirements of relevant standards for the particleboard internal bond strength. The tannin–triamine–urea cures well at 180 °C, a relatively low temperature for today’s particleboard hot pressing. As aldehydes were not used, the formaldehyde emission was found to be zero, not even in traces due to the heating of wood. The effect is ascribed to the presence of many reactive sites, such as amide, amino, and phenolic groups belonging to the three reagents used. The tannin appears to function as an additional cross-linking agent, almost a nucleating agent, for the triamine–urea hyperbranched oligomers. Chemical analysis by MALDI ToF and ¹³C NMR has shown that the predominant cross-linking reaction is that of the substitution of the tannin phenolic hydroxyls by the amino groups of the triamine. The reaction of tannin with the still-free amide groups of urea is rather rare, but it may occur with the rarer tannin flavonoid units in which the heterocyclic ring is opened. Due to the temperature gradient between the surfaces and the board core in the particleboard during hot pressing, the type and the relative balance of covalent and ionic bonds in the resin structure may differ in the surfaces and the board core. Full article

A novel ambidentate dipeptide conjugate (H(L1)) containing N-donor atoms of the peptide part and an (O,O) chelate at the hydroxypyridinone (HP) ring is synthesized and characterized. It is hoped that this chelating ligand can be useful to obtain multitargeted Co(III)/Pt(II) dinuclear complexes with anticancer potential. The Pd(II) (as a Pt(II) model but with faster ligand exchange reactions) binding strength of the ligand was studied in an aqueous solution with the combined use of pH-potentiometry and NMR. In an equimolar solution, (L1)⁻ was found to bind Pd(II) via the terminal amino and increasing number of peptide nitrogens of the peptide backbone over a wide pH range. At a 2:1 Pd(II) to ligand ratio, the presence of [Pd₂H_–x(L1)] (x = 1–4) species, with high stability and with the coordination of the (O,O) chelating set of the ligand, was detected. The reaction of H(L1) with [Co(tren)]³⁺ (tren = tris(2-aminoethyl)amine) indicated the exclusive binding of (L1)⁻ via its (O,O) donor atoms to the metal unit, while treatment of the resulting Co-complex with Pd(II) afforded the formation of a Co/Pd heterobimetallic complex in solution with an (NH₂, N_amide) coordination of Pd(II). Shortening the peptide backbone in H(L1) by one peptide unit compared to the structurally similar ambidentate chelator consisting of three peptide bonds resulted in the slightly more favorable formation of the N-coordinated Pd(II) species, allowing the tailoring of the coordination properties. Full article

Thermal and mechanical properties of poly(ionic liquid)s (PILs), an epoxidized ionic liquid-amine network, are studied via molecular dynamics simulations. The poly(ionic liquid)s are designed with two different ionic liquid monomers, 3-[2-(Oxiran-2-yl)ethyl]-1-{4-[(2-oxiran-2-yl)ethoxy]phenyl}imidazolium (EIM2) and 1-{4-[2-(Oxiran-2-yl)ethyl]phenyl}-3-{4-[2-(oxiran-2-yl)ethoxy]benzyl}imidazolium (EIM1), each of which is networked with tris(2-aminoethyl)amine, paired with different anions, bis(trifluoromethanesulfonyl)imide (TFSI⁻) and chloride (Cl⁻). We investigate how ionic liquid monomers with high ionic strength affect structures of the cross-linked polymer networks and their thermomechanical properties such as glass transition temperature (T_g) and elastic moduli, varying the degree of cross-linking. Strong electrostatic interactions between the cationic polymer backbone and anions build up their strong structures of which the strength depends on their molecular structures and anion size. As the anion size decreases from TFSI⁻ to Cl⁻, both T_g and elastic moduli of the PIL increase due to stronger electrostatic interactions present between their ionic moieties, making it favorable for the PIL to organize with stronger bindings. Compared to the EIM2 monomer, the EIM1 monomers and TFSI⁻ ions generate a PIL with higher T_g and elastic moduli. This attributes to the less flexible structure of the EIM1 monomer for the chain rotation, in which steric hindrance by ring moieties in the EIM1-based PIL enhances their structural rigidity. The $\mathsf{\pi }$-$\mathsf{\pi }$ stacking structures between the rings are found to increase in EIM1-based PIL compared to the EIM2-based one, which becomes stronger with smaller Cl⁻ ion rather than TFSI⁻. The effect of the degree of the cross-linking on thermal and mechanical properties is also examined. As the degree of cross-linking decreases from 100% to 60%, T_g also decreases by a factor of 10–20%, where the difference among the given PILs becomes decreased with a lower degree of cross-linking. Both the Young’s (E) and shear (G) moduli of all the PILs decrease with degree of cross-linking, which the reduction is more significant for the PIL generated with EIM2 monomers. Transport properties of anions in PILs are also studied. Anions are almost immobilized globally with very small structural fluctuations, in which Cl⁻ presents lower diffusivity by a factor of ~2 compared to TFSI⁻ due to their stronger binding to the cationic polymer backbone. Full article

Spontaneous atmospheric CO₂ capture as carbonate anion occurred in the synthesis of a trinuclear Cd(II) complex with tris(2-aminoethyl)amine ligand. In reaction two types of compounds were obtained and structurally characterized by X-ray diffraction on a single crystal: initially [{Cd(tren)}₃(tren)](ClO₄)₆·2H₂O (1) and subsequently [{Cd(tren)}₃(tren)][{Cd(tren)}₃(µ₃-ηCO₃)](ClO₄)₁₀ (2). The carbonate anion replaces partially the bridging tren molecule and coordinates in a µ₃ fashion. The luminescent properties of the compounds were investigated. Full article

In order to reduce the dependency of resin synthesis on petroleum resources, vanillyl alcohol which is a renewable material that can be produced from lignin has been used to synthesize bioepoxy resin. Although it has been widely reported that the curing reaction and properties of the cured epoxies can be greatly affected by the molecular structure of the curing agents, the exact influence remains unknown for bioepoxies. In this study, four aliphatic amines with different molecular structures and amine functionalities, namely triethylenetetramine (TETA), Tris(2-aminoethyl)amine (TREN), diethylenetriamine (DETA), and ethylenediamine (EDA), were used to cure the synthesized vanillyl alcohol–based bioepoxy resin (VE). The curing reaction of VE and the physicochemical properties, especially the thermomechanical performance of the cured bioepoxies with different amine functionalities, were systematically investigated and compared using different characterization methods, such as DSC, ATR–FTIR, TGA, DMA, and tensile testing, etc. Despite a higher curing temperature needed in the VE–TETA resin system, the cured VE–TETA epoxy showed a better chemical resistance, particularly acidic resistance, as well as a lower swelling ratio than the others. The higher thermal decomposition temperature, storage modulus, and relaxation temperature of VE–TETA epoxy indicated its superior thermal stability and thermomechanical properties. Moreover, the tensile strength of VE cured by TETA was 1.4~2.6 times higher than those of other curing systems. In conclusion, TETA was shown to be the optimum epoxy curing agent for vanillyl alcohol–based bioepoxy resin. Full article

Three new ionic salts containing [M(CN)₈]⁴⁻ (M = Mo^IV and W^IV) were prepared using large complex cations based on a non-conventional motif built with the tris(2-aminoethyl)amine (noted hereafter tren) ligand, [{M’(tren)}₃(μ-tren)]⁶⁺ (M’ = Cu^II and Zn^II). The crystal structures of the three compounds show that the atomic arrangement is formed by relatively isolated anionic and cationic entities. The three compounds were irradiated with a blue light at low temperature, and show a significant photomagnetic effect. The remarkable properties of these compounds are (i) the long-lived photomagnetic metastable states for the [Mo(CN)₈]⁴⁻-based compounds well above 200 K and (ii) the rare efficient photomagnetic properties of the [W(CN)₈]⁴⁻-based compound. These photomagnetic properties are compared with the singlet-triplet conversion recently reported for the K₄[Mo(CN)₈]·2H₂O compound. Full article

Three different metal oxides (basic MgO, basic-acidic Al₂O₃ and acidic-basic Nb₂O₅) characterized by comparable surface areas (MgO—130 m²/g; Al₂O₃—172 m²/g and Nb₂O₅—123 m²/g) and pore systems (domination of mesopores with narrow pore size distribution) were modified with tris(2-aminoethyl)amine (TAEA) via two methods: (i) direct anchoring of amine on metal oxide and (ii) anchoring of amine on metal oxide functionalized with (3-chloropropyl)trimethoxysilane. The obtained hybrid materials were characterized in terms of effectiveness of modifier anchoring (elemental analysis), their structural/textural properties (nitrogen adsorption/desorption, XRD), acidity/basicity of support (2-propanol dehydration and dehydrogenation, dehydration and cyclization of 2,5-hexanedione), states of modifier deposited on supports (XPS, FTIR, UV–VIS) and the strength of interaction between the modifier and the support (TG/DTG). It was evidenced that acidic-basic properties of metal oxides as well as the procedure of modification with TAEA determined the ways of amine anchoring and the strength of its interaction with the support. The obtained hybrid materials were tested in Knoevenagel condensation between furfural and malononitrile. The catalysts based on MgO showed superior activity in this reaction. It was correlated with the way of TAEA anchoring on basic MgO and the strength of modifier anchoring on the support. To the best of our knowledge tris(2-aminoethyl)amine has not been used as a modifier of solid supports for enhancement of the catalyst activity in Knoevenagel condensation. Full article

Two new nonmetal cation tetrafluoroborate phases [H₃tren](BF₄)₃ (I) and [H₃tren](BF₄)₃ HF (II) were synthesized by microwave-assisted solvothermal and characterized by single crystal X-ray diffraction, IR spectroscopy and thermal analysis DTA-TGA. [H₃tren](BF₄)₃ is cubic (P2₁3) with unit cell parameter a = 11.688(1) Å. [H₃tren](BF₄)₃•HF is trigonal (R3c) with unit cell parameters a = 15.297(6) Å and c = 12.007(2) Å. Both (I) and (II) structures can be described from isolated tetrafluoroborate BF₄^- anions, triprotonated tris-(2-aminoethyl)amine (tren) [H₃tren]³⁺. Phase (II) contains disordered BF₄^- tetrahedron and hydrofluoric acid. Full article

A review of the tripodal Schiff base (SB) complexes of tris(2-aminoethyl)amine, N_ap(CH₂CH ₂NH₂)₃ (tren), and a few closely related tripodal amines with Cr(II), Mn(III) (d⁴), Mn(II), Fe(III) (d⁵), Fe(II) (d⁶), and Co(II) (d⁷) is provided. Attention is focused on examination of key structural features, the M-N_imine, M-N_amine, or M-O and M-N_ap bond distances and N_imine-M-N(O) bite and C-N_ap-C angles and how these values correlate with spin state selection and spin crossover (SCO) behavior. A comparison of these experimental values with density functional theory calculated values is also given. The greatest number, 132, of complexes is observed with cationic mononuclear iron(II) in a N₆ donor set, Fe(II)N₆. The dominance of two spin states, high spin (HS) and low spin (LS), in these systems is indicated by the bimodal distribution of histogram plots of Fe(II)-N_imine and Fe(II)-N_{azole/pyridine} bond distances and of N_imine–Fe(II)-N_{azole/pyridine} and C-N_ap-C bond angles. The values of the two maxima, corresponding to LS and HS states, in each of these histograms agree closely with the theoretical values. The iron(II)-N_imine and iron(II)-N_{azole/pyridine} bond distances correlate well for these complexes. Examples of SCO complexes of this type are tabulated and a few of the 20 examples are discussed that exhibit interesting features. There are only a few mononuclear iron(III) cationic complexes and one is SCO. In addition, a significant number of supramolecular complexes of these ligands that exhibit SCO, intervalence, and chiral recognition are discussed. A summary is made regarding the current state of this area of research and possible new avenues to explore based on analysis of the present data. Full article

One of the major goals in the materials science is the design and development of non-toxic, versatile, and efficient drug delivery systems. The study reported in this paper concerns the syntheses of poly(amidoamine) (PAMAM) dendrimers with tris(2-aminoethyl)amine as an amine core and different terminal amines, and their attachment to silica matrix. The obtained ethylenediamine (EDA), triethylenetetramine (TETA), tris(2-aminoethyl)amine (TREN) and 4,7,10-trioxa-1,13-tridecanediamine (TRI-OXA) dendrimers were introduced to the support surface via an epoxy linker, leading to a loading efficiency in the range of 0.054–0.113 mmol g⁻¹, determined using elemental and thermogravimetric analyses. The materials exhibited high adsorption capacities towards the chosen model drugs: folic, salicylic and nicotinic acid. The investigated adsorption processes were found to follow the Freundlich isotherm model, with indication of the drugs’ structure influence on the binding efficiency. Drug-loaded hybrid materials were also described for in vitro drug release in three pH-different paraphysiological media. The highest percentage release was obtained in the tests performed at pH 2.0, ranging between 35.42 and 99.83%. Satisfactory results and the versatility of PAMAM dendrimers may lead to the application of such materials not only as drug carriers dedicated to a wide range of pharmaceutics, but also as analytical tools for pre-concentration and/or the determination of biocompound contamination in samples. Full article

In this work, we report the synthesis of a new bis(tris(2-aminoethyl)amine) azacryptand L with triphenyl spacers. The binding properties of its dicopper complex for aromatic dicarboxylate anions (as TBA salts) were investigated, with the aim to obtain potential building blocks for supramolecular structures like rotaxanes and pseudo-rotaxanes. As expected, UV-Vis and emission studies of [Cu₂L]⁴⁺ in water/acetonitrile mixture (pH = 7) showed a high affinity for biphenyl-4,4′-dicarboxylate (dfc²⁻), with a binding constant of 5.46 log units, due to the best match of the anion bite with the Cu(II)-Cu(II) distance in the cage’s cavity. Compared to other similar bistren cages, the difference of the affinity of [Cu₂L]⁴⁺ for the tested anions was not so pronounced: conformational changes of L seem to promote a good interaction with both long (e.g., dfc²⁻) and short anions (e.g., terephthalate). The good affinity of [Cu₂L]⁴⁺ for these dicarboxylates, together with hydrophobic interactions within the cage’s cavity, may promote the self-assembly of a stable 1:1 complex in water mixture. These results represent a good starting point for the application of these molecular systems as building units for the design of new supramolecular architectures based on non-covalent interactions, which could be of interest in all fields related to supramolecular devices. Full article