Dual shell-like magnetic clusters containing Ni(II) and Ln(III) (Ln = La, Pr, and Nd) ions

Dual shell-like nanoscopic magnetic clusters featuring a polynuclear nickel(II) framework encapsulating that of lanthanide ions (Ln = La, Pr, and Nd) were synthesized using Ni(NO3)(2).6H2O, Ln(NO3)(3).6H2O, and iminodiacetic acid (IDA) under hydrothermal conditions. Structurally established by crystallographic studies, these clusters are [La20Ni30(IDA)30(CO3)6(NO3)6(OH)30(H2O)12](CO3)(6).72H2O (1), [Ln20Ni21(C4H5NO4)21(OH)24(C2H2O3)6(C2O4)3(NO3)9(H2O)12](NO3)9.nH2O [C2H2O3 is the alkoxide form of glycolate; Ln = Pr (2), n = 42; Nd (3), n = 50], and {[La4Ni5Na(IDA)5(CO3)(NO3)4(OH)5(H2O)5][CO3].10H2O} infinity (4). Carbonate, oxalate, and glycolate are products of hydrothermal decomposition of IDA. Compositions of these compounds were confirmed by satisfactory elemental analyses. It has been found that the cluster structure is dependent on the identity of the lanthanide ion as well as the starting Ln/Ni/IDA ratio. The cationic cluster of 1 features a core of the Keplerate type with an outer icosidodecahedron of Ni(II) ions encaging a dodecahedral kernel of La(III). Clusters 2 and 3, distinctly different from 1, are isostructural, possessing a core of an outer shell of 21 Ni(II) ions encapsulating an inner shell of 20 Ln(III) ions. Complex 4 is a three-dimensional assembly of cluster building blocks connected by units of Na(NO3)/La(NO3)3; the structure of the building block resembles closely that of 1, with a hydrated La(III) ion internalized in the decanuclear cage being an extra feature. Magnetic studies indicated ferromagnetic interactions in 1, while overall antiferromagnetic interactions were revealed for 2 and 3. The polymeric, three-dimensional cluster network 4 displayed interesting ferrimagnetic interactions.     

Coordination polymers of La(III) as bunched infinite nanotubes and their conversion into an open-framework structure

Pyridine-2,6-dicarboxylic acid (pdcH2) reacts with LaCl3 x 7H2O under hydrothermal conditions followed by evaporation at room temperature to give a metal-organic framework structure of the empirical formula, [La(pdc)(H2O)4] x Cl (1), in the form of infinitely long bunched nanotubes. The chloride ions and water molecules occupy the tubular as well as the inter-tubular spaces. When La(NO3)3 x 7H2O is used in place of LaCl3 x 6H2O, a similar structure is formed with the empirical formula, [La(pdc)(H2O)4] x NO3 (2), where water molecules and the nitrate anions occupy the voids as in the case of 1. When an aqueous solution of AgNO3 is added to an aqueous solution of 1, the Cl- ions are replaced completely by NO3- ions to form 2; thus, the tubular structure is conserved. However, when AgBF4 is used in place of AgNO3, the tubular structure breaks down, and a new 3-D MOF structure, [La(pdc)(pdcH)(H2O)2] x 4H2O (3), is formed where the cavities are occupied by hexameric and dimeric water clusters. Structure 3 is also formed as the sole product when La(OAc)3 x xH2O is treated with pyridine-2,6-dicarboxylic acid following the method adopted for 1 and 2. Formation of the tubular structure depends on the molar ratio of the ligand and the metal. When higher than 1 equiv of the metal is taken, a linear coordination polymer, [La2(pdc)3(H2O)6] x 2H2O (4), is formed. This study provides the first nanotubular structure of a pure lanthanide metal.     

A family of 13 tetranuclear zinc(II)-lanthanide(III) complexes of a [3+3] Schiff-base macrocycle derived from 1,4-diformyl-2,3-dihydroxybenzene

A family of thirteen tetranuclear heterometallic zinc(II)-lanthanide(III) complexes of the hexa-imine macrocycle (L(Pr))(6-), with general formula Zn(II)(3)Ln(III)(L(Pr))(NO(3))(3)·xsolvents (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm or Yb), were prepared in a one-pot synthesis using a 3:1:3:3 reaction of zinc(II) acetate, the appropriate lanthanide(III) nitrate, the dialdehyde 1,4-diformyl-2,3-dihydroxybenzene (H(2)L(1)) and 1,3-diaminopropane. A hexanuclear homometallic zinc(II) macrocyclic complex [Zn(6)(L(Pr))(OAc)(5)(OH)(H(2)O)]·3H(2)O was obtained using a 2:0:1:1 ratio of the same reagents. A control experiment using a 1:0:1:1 ratio failed to generate the lanthanide-free [Zn(3)(L(Pr))] macrocyclic complex. The reaction of H(2)L(1) and zinc(II) acetate in a 1:1 ratio yielded the pentanuclear homometallic complex of the dialdehyde H(2)L(1), [Zn(5)(L(1))(5)(H(2)O)(6)]·3H(2)O. An X-ray crystal structure determination revealed [Zn(3)(II)Pr(III)(L(Pr))(NO(3))(2)(DMF)(3)](NO(3))·0.9DMF has the large ten-coordinate lanthanide(III) ion bound in the central O(6) site with two bidentate nitrate anions completing the O(10) coordination sphere. The three square pyramidal zinc(II) ions are in the outer N(2)O(2) sites with a fifth donor from DMF. Measurement of the magnetic properties of [Zn(II)(3)Dy(III)(L(Pr))(NO(3))(3)(MeOH)(3)]·4H(2)O with a weak external dc field showed that it has a frequency-dependent out-of-phase component of ac susceptibility, indicative of slow relaxation of the magnetization (SMM behaviour). Likewise, the Er and Yb analogues are field-induced SMMs; the latter is only the second example of a Yb-based SMM. The neodymium, ytterbium and erbium complexes are luminescent in the solid phase, but only the ytterbium and neodymium complexes show strong lanthanide-centred luminescence in DMF solution.     

Magnetic properties of cyano-bridged Ln3+-M3+ complexes. Part I: trinuclear complexes (Ln3+ = La, Ce, Pr, Nd, Sm; M3+ = FeLS, Co) with bpy as blocking ligand

The reaction of Ln(NO3)3(aq) with K3[Fe(CN)6] or K3[Co(CN)6] and 2,2'-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)4(mu-CN)2{Ln(H2O)4(bpy)2}2][M(CN)6].8H2O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and Sm3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [Sm2Co] (8) have been solved; they crystallize in the triclinic space group P and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding and pi-pi stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(III) and the iron(III) ions.     

Periodic trends in lanthanide and actinide phosphonates: discontinuity between plutonium and americium

The hydrothermal reactions of trivalent lanthanide and actinide chlorides with 1,2-methylenediphosphonic acid (C1P2) in the presence of NaOH or NaNO(3) result in the crystallization of three structure types: RE[CH(2)(PO(3)H(0.5))(2)] (RE = La, Ce, Pr, Nd, Sm; Pu) (A type), NaRE(H(2)O)[CH(2)(PO(3))(2)] (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy; Am) (B type), or NaLn[CH(2)(PO(3)H(0.5))(2)]·(H(2)O) (Ln = Yb and Lu) (C type). These crystals were analyzed using single crystal X-ray diffraction, and the structures were used directly for detailed bonding calculations. These phases form three-dimensional frameworks. In both A and B, the metal centers are found in REO(8) polyhedra as parts of edge-sharing chains or edge-sharing dimers, respectively. Polyhedron shape calculations reveal that A favors a D(2d) dodecahedron while B adopts a C(2v) geometry. In C, Yb and Lu only form isolated MO(6) octahedra. Such differences in terms of structure topology and coordination geometry are discussed in detail to reveal periodic deviations between the lanthanide and actinide series. Absorption spectra for the Pu(III) and Am(III) compounds are also reported. Electronic structure calculations with multireference methods, CASSCF, and density functional theory, DFT, reveal localization of the An 5f orbitals, but natural bond orbital and natural population analyses at the DFT level illustrate unique occupancy of the An 6d orbitals, as well as larger occupancy of the Pu 5f orbitals compared to the Am 5f orbitals.     

Complex formation reactions of lanthanum(III), cerium(III), thorium(IV), dioxouranyl(IV) complexes with tricine

Equilibrium studies for the heavy metal ions La(III), Ce(III), Th(IV) and UO2(IV) (M) complexes of the zwitterionic buffer tricine (L) in aqueous solution are investigated. Stoichiometry and stability constants for the different complexes formed as well as hydrolysis products of the metal cations are determined at 25 degrees C and ionic strength 0.1 M NaNO3. The stability of the formed complexes are discussed in terms of the nature of the heavy metal cation. The solid complexes are synthesized and characterized by means of elemental analysis, FTIR, and TG analysis. The general molecular formulae of the obtained complexes is suggested to be [M(L)2](NO3)n-2(H2O)x, where n = the charge of the metal cation, x = no. of water molecules.     

First 3D Pr(III)-Ni(II)-Na(I) polymer and a 3D Pr(III) open network based on pyridine-2,4,6-tricarboxylic acid

The self-assembly of pyridine-2,4,6-tricarboxylic acid (H(3)ptc) with metal salts under hydrothermal conditions gave two novel coordination polymers, {[Pr(mu(5)-ptc)(H(2)O)(2)].1.5H(2)O}(n)() (1) and {Na(2)NiPr(mu(4)-ClO(4))(mu(2)-HOCH(2)CH(2)OH)(mu(4)-ptc)(2)(H(2)O)(8)}.4.5H(2)O}(n)() (2). 1 is a 3D open network with five ptc ligands coordinating with one metal center and carboxylate groups linking metal centers to form a (4,6) net. 2 is the first Pr/Ni/Na heterotrimetallic complex, a unique 3D framework containing four different bridged ligands in the system.     

Template synthesis of lanthanide (Pr, Nd, Gd) coordination polymers with 2-hydroxynicotinic acid exhibiting ferro-/antiferromagnetic interaction

Lanthanide coordination polymers were synthesized from Pr(III), Nd(III), and Gd(III) salts; 2-hydroxynicotinic acid (Hnica); and MnSO 4.H 2O under hydrothermal conditions. In the absence of (CH 3) 3CCOONa, 1D polymers with an infinite Ln(III)-O-Ln(III) chain structure, [Pr(Hnica)(H 2O) 2SO 4] n ( 1), [Nd(Hnica)(H 2O) 2SO 4] n ( 2), and [Gd(Hnica)(H 2O) 2SO 4] n ( 3), were generated. When (CH 3) 3CCOONa was added to the synthetic systems, 2D coordination polymers {[Pr 3(Hnica) 6(H 2O) 9].3H 2O.SO 4.NO 3} n ( 4), {[Nd 3(Hnica) 6(H 2O) 9].3H 2O.SO 4.NO 3} n ( 5), and {[Gd(Hnica) 2(H 2O) 2]ClO 4.H 2O} n ( 6) were obtained. Complexes 4 and 5 both exhibit Kagome lattice structure, while 6 displays a rhombic grid structure. All complexes were characterized by elemental analysis, IR spectra, UV-vis spectra, and X-ray single-crystal diffraction. The variable-temperature magnetic susceptibility studies reveal ferromagnetic interactions between gadolinium(III) ions in 3 and 6 and antiferromagnetic interactions in 1, 2, 4, and 5.     

Lanthanide complexes of chiral 3 + 3 macrocycles derived from (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol

The enantiopure amine macrocycle H(3)L, as well as the parent macrocyclic Schiff base H(3)L1, the 3 + 3 condensation product of (1R,2R)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol, are able to form mononuclear complexes with lanthanide(III) ions. The lanthanide(III) complexes of H(3)L have been studied in solution using NMR spectroscopy and electrospray mass spectrometry. The NMR spectra indicate the presence of complexes of low C(1) and C(2) symmetry. The (1)H and (13)C NMR signals of the Lu(III) complex obtained from H(3)L have been assigned on the basis of COSY, TOCSY, NOESY, ROESY and HMQC spectra. The NMR data reveal unsymmetrical binding of lanthanide(III) ion and the presence of a dynamic process corresponding to rotation of Lu(III) within the macrocycle. The [Ln(H(4)L)(NO(3))(2)](NO(3))(2)(Ln = Sm(III), Eu(III), Dy(III), Yb(III) and Lu(III)) complexes of the cationic ligand H(4)L(+) have been isolated in pure form. The X-ray analysis of the [Eu(H(4)L)(NO(3))(2)](NO(3))(2) complex confirms the coordination mode of the macrocycle determined on the basis of NMR results. In this complex the europium(III) ion is bound to three phenolate oxygen atoms and two amine nitrogen atoms of the monoprotonated macrocycle H(4)L(+), as well as to two axial bidendate nitrate anions. In the presence of a base, mononuclear La(III), Ce(III) and Pr(III) complexes of the deprotonated form of the ligand L(3-) can be obtained. When 2 equivalents of Pr(III) are used in this synthesis Na(3)[Pr(2)L(NO(3))(2)(OH)(2)](2)NO(3).5H(2)O is obtained. The NMR, ES MS and an X-ray crystal model of this complex show coordination of two Pr(III) ions by the macrocycle L. The X-ray crystal structure of the free macrocycle H(3)L1 has also been determined. In contrast to macrocyclic amine H(3)L, the Schiff base H(3)L1 adopts a cone-type conformation resembling calixarenes.     

Synthesis, characterization and DNA-binding studies on La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide

La(III) and Ce(III) complexes containing ligand of N-phenyl-2-pyridinecarboxamide (HL) were synthesized and characterized by elemental analyses, conductivity measurement, IR spectra and thermal analysis. The general formulas of the complexes were [Ln(HL)(3)(H(2)O)(2)](NO(3))(3).2H(2)O [Ln=La(III), Ce(III)]. The results indicated that the oxygen of carbonyl and the nitrogen of pyridyl coordinated to Ln(III), and there were also two water molecules taking part in coordination. Ln(III) and HL formed 1:3 chelate complexes and the coordination number was eight. The interaction between the complexes and DNA was studied by means of UV-vis spectra, fluorescence spectra, SERS spectra and agarose gel electrophoresis. The results showed that complexes can bind to DNA. The binding ability decreased in following order: La(III) complex, Ce(III) complex, and HL. The interaction modes between DNA and the three compounds were found to be mainly intercalative.     

Three-dimensional lanthanide(III)-copper(II) compounds based on an unsymmetrical 2-pyridylphosphonate ligand: an experimental and theoretical study

Based on an unsymmetrical 2-pyridylphosphonate ligand, two types of Ln(III)-Cu(II) compounds with three-dimensional structures were obtained under hydrothermal conditions, namely, Ln(2)Cu(3)(C(5)H(4)NPO(3))(6).4H(2)O (1.Ln; Ln=La, Ce, Pr, Nd) and Ln(2)Cu(3)(C(5)H(4)NPO(3))(6) (2.Ln; Ln=Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho). Compounds 1.Ln are isostructural and crystallize in chiral cubic space group I2(1)3. In these structures, each Ln ion is nine-coordinate and has a tricapped triprismatic geometry, while each Cu center is six-coordinate with an octahedral environment. The {LnO(9)} polyhedra and {CuN(2)O(4)} octahedra are connected by edge sharing to form an inorganic open framework structure with a 3-connected 10-gon (10,3) topology in which the Ln and Cu atoms are alternately linked by the phosphonate oxygen atoms. Compounds 2.Ln are isostructural and crystallize in trigonal space group R3. In these structures, the {LnO(6)} octahedra are triply bridged by the {CPO(3)} tetrahedra by corner sharing to form an infinite chain along the c axis. Each chain is connected to its six equivalents through corner sharing of {CPO(3)} tetrahedra and {CuN(2)O(2)} planes to form a three-dimensional framework structure in which the Ln and Cu atoms are linked purely by O-P-O units. The formation of these two types of structures is rationalized by quantum chemical calculations, which showed that both the lanthanide contraction and the electron configuration of Cu(II) play important roles. When Cu(II) was replaced by Zn(II), only the first type of compounds resulted. The magnetic properties of complexes 1.Ln and 2.Ln were investigated. The nature of Ln(III)-Cu(II) (Ln=Ce, Pr, Nd) interactions is illustrated by comparison with their Ln(III)-Zn(II) analogues.     

Absorption spectral analysis of 4f-4f transitions for the complexation of Pr(III) and Nd(III) with thiosemicarbazide in absence and presence of Zn(II) in aqueous and organic solvents

The complexation of thiosemicarbazide with Pr(III) and Nd(III) in absence and presence of Zn(II), a soft metal ion in aqueous and organic solvents like CH(3)OH,CH(3)CN, dioxane (C(4)H(8)O(2)) and DMF (C(3)H(7)NO) and their equimolar mixtures are discussed by employing absorption difference and comparative absorption spectrophotometry. Complexation of thiosemicarbazide with Pr(III) and Nd(III) is indicated by the changes in the absorption intensity following the subsequent changes in the oscillator strength of different 4f-4f bands and Judd-Ofelt intensity (T(λ)) parameters. The other spectral parameters like energy interaction parameters namely Slater-Condon (F(k)), Racah (E(k)), Lande (ξ(4f)), Nephelauxetic ratio (β) and bonding parameters (b(1/2)) are further computed to explain the nature of complexation. The difference in the energy parameters with respect to donor atoms and solvents reveal that the chemical environment around the lanthanide ions has great impact on f-f transition and any change in the environment result in modification of the spectra. Various solvents and their equimolar mixtures are also used to discuss the participation of solvents in the complexation.     

Catalytic Hydrolysis of Phosphate Diesters by Lanthanide(III) Cryptate (2.2.1) Complexes

Lanthanide(III) Cryptate (2.2.1) chlorides (Ln(2.2.1)Cl(3); Ln = La (1a), Ce(1b), and Eu(1c); (2.2.1) = 4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5]tricosane) are effective for the catalytic hydrolysis of bis(4-nitrophenyl) phosphate. Kinetic studies reveal that the europium(III) complex (1c) catalyzes the hydrolysis to produce 6 equiv of 4-nitrophenol with a significant rate (k(1) = 1.5 x 10(-)(4) s(-)(1) at 0.40 mM) at pH 8.5 and 50 degrees C. The catalytic activity of the complexes is increased with decreasing the ionic size, i.e, La < Ce < Eu. While the use of hydrogen peroxide further increase the activity of 1b (k(1) = 1.6 x 10(-)(3) s(-)(1) at 0.40 mM), the presence of molecular oxygen does not affect the activity at all. Crystal of 1a.CH(3)OH([La(2.2.1)(Cl)(2)](Cl)(CH(3)OH)) belongs to the space group Pnma with a = 17.072(3) ?, b = 19.037(3) ?, c = 14.725(2) ?, V = 4786(1) ?(3), Z = 8, D(x)() = 1.691 g cm(-)(3), &mgr; = 21.7 cm(-)(1). The encryptated metal ion is nine-coordinated, and all the heteroatoms of the cryptate (2.2.1) ligand coordinate the metal center to form a bowl-shaped structure. Two coordinating chloride anions are located on the open face with a cis geometry. The existence of coordinated water to the europium(III) complex 1c in the aqueous solution was confirmed by time-resolved Eu(III) luminescence spectroscopy. From the decay constants in H(2)O and D(2)O, the numbers of coordinated water molecules (q) are found to be 3.02 at pH of 5.0. The above kinetic and spectroscopic observation are supportive of mechanisms in which the metal complexes act as a center for binding and activation as well as a source of nucleophilic metal hydroxides.     

New luminescent solids in the Ln-W(Mo)-Te-O-(Cl) systems

Solid-state reactions of lanthanide(III) oxide (and/or lanthanide(III) oxychloride), MoO3 (or WO3), and TeO2 at high temperature lead to eight new luminescent compounds with four different types of structures, namely, Ln2(MoO4)(Te4O10) (Ln = Pr, Nd), La2(WO4)(Te3O7)2, Nd2W2Te2O13, and Ln5(MO4)(Te5O13)(TeO3)2Cl3 (Ln = Pr, Nd; M = Mo, W). The structures of Ln2(MoO4)(Te4O10) (Ln = Pr, Nd) feature a 3D network in which the MoO4 tetrahedra serve as bridges between two lanthanide(III) tellurite layers. La2(WO4)(Te3O7)2 features a triple-layer structure built of a [La2WO4]4+ layer sandwiched between two Te3O72- anionic layers. The structure of Nd2W2Te2O13 is a 3D network in which the W2O108- dimers were inserted in the large tunnels of the neodymium(III) tellurites. The structures of Ln5(MO4)(Te5O13)(TeO3)2Cl3 (Ln = Pr, Nd; M = Mo, W) feature a 3D network structure built of lanthanide(III) ions interconnected by bridging TeO32-, Te5O136-, and Cl- anions with the MO4 (M = Mo, W) tetrahedra capping on both sides of the Ln4 (Ln = Pr, Nd) clusters and the isolated Cl- anions occupying the large apertures of the structure. Luminescent studies indicate that Pr2(MoO4)(Te4O10) and Pr5(MO4)(Te5O13)(TeO3)2Cl3 (M = Mo, W) are able to emit blue, green, and red light, whereas Nd2(MoO4)(Te4O10), Nd2W2Te2O13, and Nd5(MO4)(Te5O13)(TeO3)2Cl3 (M = Mo, W) exhibit strong emission bands in the near-IR region.     

Synthesis and crystal structure of complex of Ce(NO_3)_3 with N-(3-methyl-pyridin-2-yl)-formimidoyl-(3-methyl-pyridin-2-yl) hydrazone

Rare earth complexes with organic ligands have been used as luminescence-material usually. Except their luminescent property, the complexes of trivalent lanthanide ions have low toxicity and powerful para-magnetic properties[1,2], so the lanthanide complexes are associated with important biological uses as diag-nostic tools and medicines[36]. Recently, there are some reports on Ce(III) complexes, some of which show anti-cancer activities[7]. S- tetrazines can be used as poly-dentate chelatin…     

Synthesis and crystal structures of new lanthanide isonicotinates: coordination polymers and molecular complexes

New coordination polymers [Ce(C5H4NCOO)3(H2O)2] · 0.5C6H4N2 · 1.5H2O, [Ln(C5H4N-COO)3(H2O)2] (Ln = Ce, Pr) and [Ho(C5H4NCOO)2(H2O)4]NO3, and the tetranuclear complex [Ho4(OH)4(C5H4NCOO)6(H2O)8](NO3)2 · 3.5C6H4N2 · 5H2O were prepared by heating aqueous solutions of lanthanide(III) nitrates with 4-cyanopyridine under conditions of hydro-thermal synthesis. X-ray diffraction study demonstrated that the lanthanide atoms in the coordination polymers are bridged in chains through coordination to the carboxyl group of isonicotinic acid. The metal atoms in the tetranuclear complex are bound in pairs by six bidentate isonicotinate ligands.     

A supramolecular spin crossover Fe(III) complex and its Cr(III) isomer: stabilization of water-chloride cluster within supramolecular host

The metal complexes, [M(Hdammthiol)(2)]Cl·3H(2)O [M = Cr(III) (1), Fe(III) (2)] [where H(2)dammthiol is the thiol form of the ligand, diacetylmonoxime morpholine N-thiohydrazone] were synthesized by metal template reactions of diacetylemonoxime with morpholine N-thiohydrazide in the presence of CrCl(3)·6H(2)O and FeCl(3)·6H(2)O. Both the complexes (1 and 2) were characterized by single crystal X-ray crystallography, spectroscopic (IR and UV-vis), M?ssbauer and TGA analyses. The single crystal X-ray studies of both complexes show that the supramolecular hosts, constructed by the discrete mononuclear complexes, form supramolecular channels along the c-axis which are filled up by water-chloride clusters. In both complexes, the 1D water-chloride chain with chair-like architecture within the supramolecular hosts presents novelty. The magnetic measurement study of Fe(III) complex shows a spin crossover from S = 1/2 at 2.5 K to S = 5/2 at 300 K. At very low temperature, the presence of strong cooperative hydrogen bonding interactions stabilizes the S = 1/2 state.     

Microhydration of NO3(-): a theoretical study on structure, stability and IR spectra

A systematic study on the structure and stability of nitrate anion hydrated clusters, NO3(-) x n H2O (n = 1-8) are carried out by applying first principle electronic structure methods. Several possible initial structures are considered for each size cluster to locate equilibrium geometry by applying a correlated hybrid density functional with 6-311++G(d,p) basis function. Three different types of arrangements, namely, symmetrical double hydrogen bonding, single hydrogen bonding and inter-water hydrogen bonding are obtained in these hydrated clusters. A structure having inter-water hydrogen bonding is more stable compared to other arrangements. Surface structures are predicted to be more stable over interior structures. Up to five solvent H2O molecules can stay around solute NO3(-) anion in structures having an inter-water hydrogen-bonded cyclic network. A linear correlation is obtained for weighted average solvent stabilization energy with the size (n) of the hydrated cluster. Distinctly different shifts of IR bands are observed in these hydrated clusters for different kinds of bonding environments of O-H and N=O stretching modes compared to isolated H2O and NO3(-) anion. Weighted average IR spectra are calculated on the basis of statistical population of individual configurations of each size cluster at 150 K.     

Density Functional Theory Study of Water Diffusion and Clustering on Pd（111）

1 INTRODUCTION The interaction of water molecules with metal sur- faces plays a vital role in a number of important pro- cesses, such as corrosion, heterogeneous catalysis, electrochemical processes in aqueous solutions, hydrogen production, etc.[1] The structure and pro- perties of water adsorbed on well-defined metal sur- faces have been the subject of numerous experi- mental and theoretical investigations. There have been a number of experimental studies of water on metal surfaces throu…     

Solid compounds of Ce(III), Pr(III), Nd(III), and Sm(III) ions with chrysin

New solid amorphous compounds of Ce(III), Pr(III), Nd(III), and Sm(III) with 5,7-dihydroxyflavone (L,chrysin) were obtained. Their composition and some physicochemical properties were studied by elementary analysis, thermogravimetric analysis, magnetic measurements, ¹H NMR, UV/Vis, and infrared spectroscopies. Upon heating, the hydrated compounds [LnL₂(H₂O)₂Cl]·2H₂O decomposed to the oxides. Structure of the compounds was elucidated on the basis of obtained results. It was found that chelation of the metal ion occurs at the 5-hydroxy-4-keto site.