Basis sets applied to the theoretical study of the vibrational structure of hexaaquaaluminum(III) ion

Gaussian basis sets were developed with the Generator Coordinate Hartree-Fock (GCHF) method for the atoms from H (14s), O (23s16p), and Al (29sl9p) in the ground state. These basis sets were then contracted to 3s (12,1,1), 5s3p (18,2,1,1,1/14,1,1), and 7s5p (20,3,2,1,1,1,1/14,2,1,1,1) for H, O and Al atoms, respectively, by a standard procedure. The quality of contracted basis sets in molecular calculations was evaluated through studies of the total and orbital (epsilon(HOMO) and epsilon(HOMO-1)) energies at the HF level for the hexaaquaaluminum(III) ion, [AI(H(2)O)(6)](3+). For the O atom, the 5s3p was supplemented with d polarization function and it was used in combination with 3s, and 7s5p for H and Al atoms was used to the theoretical interpretation of the Infrared (IR) spectrum of hexaaquaaluminum(III) ion. The calculations of the IR-spectrum were also performed at the HF level and it showed that the basis sets obtained with the aid of GCHF method lead to the selection of useful contracted Gaussian basis sets for the theoretical study of vibrational property of ionic specie of our interest. (C) 2004 Elsevier B.V. All rights reserved.

A napthelene-pyrazol conjugate: Al(III) ion-selective blue shifting chemosensor applicable as biomarker in aqueous solution

A newly synthesized and crystalographically characterized napthelene-pyrazol conjugate, 1-(5-phenyl-1H-pyrazole-3-ylimino)-methyl]-naphthalen-2-ol (HL) behaves as an Al(III) ion-selective chemosensor through internal charge transfer (ICT)-chelation-enhanced fluorescence (CHEF) processes in 100 mM HEPES buffer (water-DMSO 5 : 1, v/v) at biological pH with almost no interference of other competitive ions. This mechanism is readily studied from electronic, fluorimetric and H-1 NMR titration. The probe (HL) behaved as a highly selective fluorescent sensor for Al(III) ions as low as 31.78 nM within a very short response time (15-20 s). The sensor (HL), which has no cytotoxicity, is also efficient in detecting the distribution of Al(III) ions in HeLa cells via image development under fluorescence microscope.

The phase transitions of hetero atoms substituted molecular sieves Me-VPI-5(Me=Mg, Ti, Sn, Si) and their influence on spectra structures of Eu(III) ion

The hetero atom substituted aluminophosphate molecular sieves Me-VPI-5(Me = Mgt Ti, Sn, Si) were synthesized hydrothermally. Rare earth ions are originally doped into these microporous materials by aqueous solution ion exchange procedures. The phase transitions of the microporous materials are investigated by high-temperature and high-pressure experimental techniques. The influence of the phase transitions on the rare earth ions' spectral structures is discussed, With the increase of temperature, Eu(II)Mg-VPI-5 is converted into Eu(II)Mg-AIPO(4)-8, then into tridymite phase. The pressure has a notable influence on Eu(II) ion's spectral structures. The spectral structures have changed regularly with the increase of pressure.

Supramolecular assemblies of metal ions in complex bimetallic and trimetallic salts based on hexacyanoferrate(III) ion

Two complex heterometallic salts with formulae Tl-6[Fe(CN)(6)](1) (33)(NO3)(OH) (1) and [Co(bpy)(2)(CN)(2)](2){[Ag(CN)(2)](0) (5)[Fe(CN)(6)](0) (5)} 8H(2)O (2) have been synthesized and fully characterized Single crystal X-ray analyses reveal that compound 1 is comprised of discrete Tl+ cations and [Fe(CN)(6)](3-) anions together with OH- and NO3- anions Compound 2 contains [Co(bpy)(2)(CN)(2)](+) cations and {[Ag(CN)(2)][Fe(CN)(6)]}(-) anions together with eight molecules of water of crystallization Both structures form unprecedented three-dimensional supramolecular networks via non covalent interactions Another important observation is that the stereochemically active inert (lone) pair present on Tl+ plays little role in controlling the structure of 1 The water molecules in 2 play important roles in providing stability organizing a supramolecular network through hydrogen bonding In the syntheses of 1 and 2 Fe(II) is oxidized to Fe(III) and Co(II) to Co(III) respectively facilitating the formation of the salts that are obtained Both compounds exhibit photoluminescence emission in solution near the visible region.

Luminescence enhancement of the Tb(III) ion with the thenoyltrifluoroacetonate ligand acting as an efficient sensitizer

The synthesis, structural investigation, and photophysical properties of the complex [Tb(TTA)(2)(NO(3)) (TPPO)(2)] are reported. Unlike the analog tris-diketonate complex [Tb(TTA)(3)(TPPO)(2)], the new complex presents abnormally high luminescence intensity centered on the terbium ion. Our results clearly suggest a higher energy transfer efficiency from the TEA antenna ligand to the Tb(III) ion in the bis-diketonate complex compared with that in the tris-diketonate complex. A mechanism involving the increasing of triplet state energy when one TTA ligand is replaced by the NO(3)(-) group in the first coordination sphere is suggested and experimentally investigated to explain the anomalous luminescence properties of the new complex [Tb(TTA)(2)(NO(3))(TPPO)(2)]. (C) 2010 Elsevier B.V. All rights reserved.

Design of Gaussian basis sets to the theoretical interpretation of IR-spectrum of hexaaquachromium (III) ion, tetraoxochromium (IV) ion, and tetraoxochromium (VI) ion

The Generator Coordinate Hartree-Fock (GCHF) method is employed to design 16s, 16s10p, 24s17p13d, 25s17p13d, and 26s17p Gaussian basis sets for the H ((2)S), O ((3)P), O(2-) ((1)S), Cr(3+) ((4)F), Cr(4+) ((3)F), and Cr(6+) ((1)S) atomic species. These basis sets are then contracted to (4s) for H ((2)S), (6s4p) for O ((3)P), and O(2-) ((1)S), (986p3d) for Cr(3+) ((4)F), (10s8p3d) for Cr(4+) ((3)F), and (13s7p) for Cr(6+) (1S) by a standard procedure. For evaluation of the quality of those basis sets in molecular calculations, we have accomplished studies of total and orbital (HOMO and HOMO-1) energies at the HF-Roothaan level for the molecular species of our interest. The results obtained with the contracted basis sets are compared to the values obtained with our extended basis sets and to the standard 6-311G basis set from literature. Finally, the contracted basis sets are enriched with polarization function and then utilized in the theoretical interpretation of IR-spectrum of hexaaquachromium (III) ion, [Cr(H(2)O)(6)](3+), tetraoxochromium (IV) ion, [CrO(4)](4-), and tetraoxochromium (VI) ion, [CrO(4)](2-). The respective theoretical harmonic frequencies and IR-intensities were computed at the density functional theory (DFT) level. In the DFT calculations we employed the Becke's 1988 functional using the LYP correlation functional. The comparison between the results obtained and the corresponding experimental values indicates a very good description of the IR-spectra of the molecular ions studied, and that the GCHF method is still a legitimate alternative for selection of Gaussian basis sets. (C) 2003 Elsevier B.V. All rights reserved.

Contracted GTF basis sets applied to the theoretical interpretation of the Raman spectrum of hexaaquachromium(III) ion

Contracted GTF basis sets designed with aid of the Generator Coordinate Hartree-Fock (GCHF) method for H(2S), O2-(1S), and Cr3+(4F) atomic species are applied to perform theoretical interpretation of the Raman spectrum of hexaaquachromium(III) ion. The 16s, 16s 10p, and 24s17p13d GTF basis sets were contracted to [4s] for H atom, [6s4p], and [9s6p3d] for O2- and Cr3+, respectively, by Dunning's scheme. For Cr3+, the [9s6p3d] basis set was enriched with f polarization function and used in combination com [4s] and [6s4p] in the study of our interest. The results obtained in this report show that the contracted GTF basis sets used are a useful alternative for the theoretical interpretation of Raman spectrum of hexaaquachromium(III) ion and that GCHF method is an effective alternative to selection of GTF basis sets for theoretical study of vibrational properties of poliatomic species. © 2003 Elsevier Science B.V. All rights reserved.

Photocytotoxicity and DNA photocleavage activity of La(III) and Gd(III) complexes of phenanthroline bases

Lanthanide(II) complexes La(B)(acac)(3)] (1-3) and Gd(B)(acac)(3)] (4-6), where B is a N,N-donor phenanthroline base, viz., 1,10-phenanthroline (phen in 1, 4), dipyrido3,2-d:2',3'-f]quinoxaline (dpq in 2, 5) and dipyrido3,2-a:2',3'-c]phenazine (dppz in 3, 6), have been prepared and characterized. The Gd(111) complexes 4 6 are structurally characterized by single crystal X-ray crystallography. The complexes display GdO6N2 coordination with the ligands showing bidentate chelating mode of bonding. The complexes are non-electrolytic in aqueous DMF and exhibit ligand-centered absorption bands in the UV region. The dppz complexes show a band at 380 nm in DMF. The La(111) complexes are diamagnetic. The Gd(III) complexes are paramagnetic with magnetic moment that corresponds to seven unpaired electrons. The Complexes are avid binders to calf thymus DNA giving K-b values in the range of 4.7 x 10(4) 6.1 x 10(5) M-1 with a relative binding order: 3, 6 (dppz) > 2, 5 (dpq) > 1, 4 (phen). The binding data suggest DNA surface and/or groove binding nature of the complexes. The dpq and dppz complexes efficiently cleave SC DNA to its nicked circular form in UV-A light of 365 nm via formation of both singlet oxygen (O-1(2)) and hydroxyl radical (HO center dot) species. The dppz complexes 3 and 6 exhibit significant PDT effect in He La cervical cancer cells giving respective IC50 value of 460(+/- 50) and 530(+/- 30) nM in UV-A light of 365 rim, and are essentially non-toxic in dark with an IC50 value of >100 mu M. The dppz ligand alone is cytotoxic in dark and UV-A light. A significant decrease in the dark toxicity of the dppz base is observed on binding to the Ln(III) ion while retaining its photocytotoxicity.

Mode coupling theory analysis of electrolyte solutions: Time dependent diffusion, intermediate scattering function, and ion solvation dynamics

A self-consistent mode coupling theory (MCT) with microscopic inputs of equilibrium pair correlation functions is developed to analyze electrolyte dynamics. We apply the theory to calculate concentration dependence of (i) time dependent ion diffusion, (ii) intermediate scattering function of the constituent ions, and (iii) ion solvation dynamics in electrolyte solution. Brownian dynamics with implicit water molecules and molecular dynamics method with explicit water are used to check the theoretical predictions. The time dependence of ionic self-diffusion coefficient and the corresponding intermediate scattering function evaluated from our MCT approach show quantitative agreement with early experimental and present Brownian dynamic simulation results. With increasing concentration, the dispersion of electrolyte friction is found to occur at increasingly higher frequency, due to the faster relaxation of the ion atmosphere. The wave number dependence of intermediate scattering function, F(k, t), exhibits markedly different relaxation dynamics at different length scales. At small wave numbers, we find the emergence of a step-like relaxation, indicating the presence of both fast and slow time scales in the system. Such behavior allows an intriguing analogy with temperature dependent relaxation dynamics of supercooled liquids. We find that solvation dynamics of a tagged ion exhibits a power law decay at long times-the decay can also be fitted to a stretched exponential form. The emergence of the power law in solvation dynamics has been tested by carrying out long Brownian dynamics simulations with varying ionic concentrations. The solvation time correlation and ion-ion intermediate scattering function indeed exhibit highly interesting, non-trivial dynamical behavior at intermediate to longer times that require further experimental and theoretical studies. (c) 2015 AIP Publishing LLC.

The optical properties and the natural lifetime calculation of a Sm(III) complex

The photophysical properties of the complex Sm(PM)(3)(TP)(2) [PM = 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone, TP = triphenyl phosphine oxide] are determined in crystal state, and energy transfer process is modeled for ligands to center Sm(III) ion. The characteristic luminescence of Sm(III) is sensitized by PM and TP, and most of transitions from excited state (4)G(5/2) of Sm3+ are detected.

Crystal structure of a Pr-III complex with a novel macrocyclic ligand

The crystal structure of a novel macrocyclic ligand complex of Pr-III, C112H178O52N8S4Pr2, [Pr2L2(HL)(2)(H2O)(6)]. 22H(2)O is reported. The macrocyclic ligand has pendant acetic acid through which the ligand is coordinated to the Pr-III ion. For the dimeric unit, [Pr2L2(HL)(2)(H2O)(6)], two Pr-III ions are connected by two bridging-chelating carboxyl groups and two bridging carboxyl groups of the ligands, and each Pr-III ion is also bonded to a unidentate carboxyl group of the ligand and three water molecules. The dimeric units are bridged by four ligands through their carboxyl groups to form an infinite one-dimensional chain. The coordination number of the Pr-III ion is nine, with a distorted tricapped trigonal prismatic configuration. (C) 1997 Elsevier Science Ltd.

ELECTROCHEMICAL-BEHAVIOR OF YTTRIUM ION IN LICL-KCL-NACL EUTECTIC MELT

The electrochemical reduction of yttrium ion on a molybdenum electrode in a LiCl-KCl-NaCl eutectic melt at 723 K was found to be almost reversible and to proceed by a one-step three electron reaction. The diffusion coefficient D of the Y(III) ion was measured to be (3.3 +/- 0.4) x 10(-6) cm2 s-1 by cyclic voltammetry, (5.0 +/- 0.9) x 10(-6) cm2 s-1 by the rotating disk electrode method, and (7.1 +/- 0.7) x 10(-6) cm2 s-1 by chronopotentiometry. The D values obtained by the latter two methods are in fairly good agreement with each other. The rather low D value obtained by cyclic voltammetry might be attributed to the fact that yttrium metal can dissolve slightly in the chloride melt. The standard potential of Y(III)/Y(0) couple was determined to be (-3.174 +/- 0.006) V (vs. Cl2/Cl-) by open-circuit potentiometry, (-3.15 +/- 0.02) V (vs. Cl2/Cl-) by the rotating disk electrode method and (-3.16 +/- 0.02) V (vs. Cl2/Cl) by chronopotentiometry. These three values are in good agreement with each other. Several types of Ni-Y intermetallic compounds were found to be formed on a nickel electrode.

Visible and Near-Infrared Emission by Samarium(III)-Containing Ionic Liquid Mixtures

Highly luminescent anionic samarium(III) beta-diketonate and dipicolinate complexes were dissolved in the imidazolium ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(6)mim][Tf2N]. The solubility of the complexes in the ionic liquid was ensured by a careful choice of the countercation of the samarium(III) complex. The samarium(III) complexes that were considered are [C(6)mim][SM(tta)(4)], where tta is 2-thenoyltrifluoroacetonate; [C(6)mim][Sm(nta)(4)], where nta is 2-naphthoyltrifluoroacetonate; [C(6)mim][Sm(hfa)(4)], where hfa is hexafluoroacetylacetonate; and [choline](3)-[Sm(dpa)(3)], where dpa is pyridine-2,6-dicarboxylate (dipicolinate) and [choline](+) is (2-hydroxyethyl)trimethyl ammonium. The crystal structures of the tetrakis samarium(III) P-diketonate complexes revealed a distorted square antiprismatic coordination for the samarium(III) ion in all three cases. Luminescence spectra were recorded for the samarium(III) complexes dissolved in the imidazolium ionic liquid as well as in a conventional solvent, that is, acetonitrile or water for the beta-diketonate and dipicolinate complexes, respectively. These experiments demonstrate that [C(6)mim][Tf2N] is a suitable spectroscopic solvent for studying samarium(III) luminescence. High-luminescence quantum yields were observed for the samarium(III) beta-diketonate complexes in solution.

Intense near-infrared luminescence of anhydrous lanthanide(III) iodides in an imidazolium ionic liquid

Anhydrous neodymium(III) iodide and erbium(Ill) iodide were dissolved in carefully dried batches of the ionic liquid 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C(12)mim][Tf2N]. Provided that the ionic liquid had a low water content, intense near-infrared emission could be observed for both the neodymium(III) ion and for the erbium(III) ion. Luminescence lifetimes have been measured, and the quantum yield of the neodymium(III) sample has been measured. Exposure of the hygroscopic samples to atmospheric moisture conditions caused a rapid decrease of the luminescence intensities. (C) 2004 Elsevier B.V. All rights reserved.

Lanthanide(III) nitrobenzenesulfonates as new nitration catalysts: The role of the metal and of the counterion in the catalytic efficiency

Lanthanide(III) complexes of p-nitrobenzenesulfonic acid, Ln(p-NBSA)(3), m-nitrobenzenesulfonic acid, Ln(m-NBSA)(3), and 2,4-nitrobenzenesulfonic acid, Ln(2,4-NBSA)(3), were prepared, characterized and examined as catalyst for the nitration of benzene, toluene, xylenes, naphthalene, bromobenzene and chlorobenzene. The initial screening of the catalysts showed that lanthanum(III) complexes were more effective than the corresponding ytterbium(III) complexes, and that catalysts containing the bulky 2,4-NBSA ligand were less effective than the catalyst containing p-NBSA (nosylate) or m-NBSA ligands. Examination of a series of Ln(p-NBSA)(3) and Ln(m-NBSA)(3) catalysts revealed that there is a clear correlation between the ionic radii of the lanthanide(III) ions and the yields of nitration, with the lighter lanthanides being more effective. The X-ray single crystal structure of Yb(m-NBSA)(3).6H(2)O shows that two m-NBSA ligands are directly bound to the metal centre while the third ligand is not located in the first coordination sphere, but it is hydrogen bonded to one of the water molecules which is coordinated to ytterbium(III). NMR studies suggest that this structure is preserved under the conditions used in the nitration reaction. The structure of Yb(m-NBSA)(3) is markedly different from the structure of the well-known ytterbium(III) triflate catalyst. The coordination of the nitrobenzenesulfonate counterion to the lanthanide(III) ion suggests that steric effects might play an important role in determining the efficiency of these novel nitration catalysts. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).