Ester and Ketone Groups Substituted Mono- and Di- Azo-coupled Azocalix[4]arenes as Extractant for Hg+ and Hg2+, or Cr3+Cations

This article describes extraction properties of mono- (A1–A8) and di- (B1–B8) substituted azocalix[4]arene analogues. The ionophore solvent extractions of alkaline-earth (Sr²⁺), basic metal (Pb²⁺) and transition metal cations (Ag⁺, Hg⁺, Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, Cr³⁺) from aqueous phase to organic phase were carried out by azocalix[4]arene derivatives. It has been observed that they show a good extraction behavior toward selected heavy metal (Hg) and toxic metal (Cr), while A4 and B4 prefer Hg⁺, Hg²⁺ and Cr³⁺ among transition metal cations, respectively. The azocalix[4]arenes (A1–A8) and (B1–B8) are not efficient extractants for all of the selected metal cations, whereas A4 and B4 are selective only for Hg metal cation.     

Theoretical study on structures and stability of HC2P isomers

 The structures and isomerization pathways of various HC₂P isomers in both singlet and triplet states are investigated at the B3LYP/6-311G(d,p), QCISD/6-311G(d,p) (for isomers only) and single-point CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) levels. At the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) level, the lowest-lying isomer is a linear HCCP structure ³ 1 in the ³∑⁻ state. The second low-lying isomer has a CPC ring with exocyclic CH bonding ¹ 5 in a singlet state at 10.5 kcal/mol. The following third and fourth low-lying isomers are a singlet bent HCCP structure ¹ 1 at 20.9 kcal/mol and a bent singlet HPCC structure ¹ 3 at 35.8 kcal/mol, respectively. Investigation of the HC₂P potential-energy surface indicates that in addition to the experimentally known isomer ³ 1, the other isomers ¹ 1, ¹ 3 and ¹ 5 also have considerable kinetic stability and may thus be observable. However, the singlet and triplet bent isomers HCPC ¹ 2 and ³ 2 as well as the triplet bent isomer HPCC ³ 3 are not only high-lying but are also kinetically unstable, in sharp contrast to the situation of the analogous HCNC and HNCC species that are both kinetically stable and that have been observed experimentally. Furthermore, the reactivity of various HC₂P isomers towards oxygen atoms is briefly discussed. The results presented here may be useful for future identification of the completely unknown yet kinetically stable HC₂P isomers ¹ 1, ¹ 3 and ¹ 5 either in the laboratory or in interstellar space. Received: 5 November 2000 / Accepted: 25 November 2001 / Published online: 8 April 2002     

Drag on an ellipsoid particle in free-molecular plasma flow

Based on the analysis of molecular gas dynamics, the drag and moment acting on an ellipsoid particle of revolutionX ²/a ²+Y ²/a ²+Z ²/c ²=1, as an example of nonspherical particles, are studied under the condition of free-molecular plasma flow with thin plasma sheaths. A nonzero moment which causes nonspherical particle self-oscillation and self-rotation around its own axis in the plasma flow—similar to the pitching moment in aerodynamics—is discovered for the first time. When the ratio of axis lengthc/a is unity, the moment is zero and the drag formula are reduced to the well-known results of spherical particles. The effects of the particle-plasma relative velocity, the plasma temperature, and the particle materials on the drag and moment are also investigated.     

Co(II), Ni(II), and Cu(II) Complexation with Isatin Aminoguanisone and Nitroaminoguanisone

New complexes of bivalent Co, Ni, and Cu with isatin aminoguanisone (HL) and nitroaminoguanisone (HL¹) of the composition ([Co(HL)₂]Cl₂ (I), [Ni(HL)₂]Cl₂ (II), [Cu(L)Cl] (III), [Co(L¹)₂] (IV), [Ni(L¹)₂] (V), and [Cu(L¹)₂] (VI) are synthesized. Their molecular conductivities and effective magnetic moments are measured and thermal stabilities are studied. The type of the ligand coordination in I–VI is proposed on the basis of IR data. The summary of physicochemical data for I–VI and the energy calculations for their molecules by the molecular mechanics method made it possible to establish stoichiometry of the coordination polyhedra of the complexes.     

AB INITIO MOLECULAR ORBITAL STUDY OF 1,2-DITHIANE AND 1,2,4,5-TETRATHIANE

Ab initio calculations at HF/6-31+G? level of theory for geometry optimization, and MP2/6-31+G?//HF/6-31+G? and B3LYP/6-31+G?//HF/6-31+G? levels for a single-point total energy calculation, are reported for the chair and twist conformations of 1,2-dithiane (1), 3,3,6,6-tetramethyl-1,2-dithiane (2), 1,2,4,5-tetrathiane (3), and 3,3,6,6-tetramethyl-1,2,4,5-tetrathiane (4). The C₂ symmetric chair conformations of 1 and 2 are calculated to be 21.9 and 8.6 kJ mol^?1 more stable than the corresponding twist forms. The calculated energy barriers for chair-to-twist processes in 1 and 2 are 56.3 and 72.8 kJ mol^?1, respectively. The C_2h symmetric chair conformation of 3 is 10.7 kJ mol^?1 more stable than the twist form. Interconversion of these forms takes place via a C₂ symmetric transition state, which is 67.5 kJ mol^?1 less stable than 3-Chair. The D₂ symmetric twist-boat conformation of 4 is calculated to be 4.0 kJ mol^?1 more stable than the C_2h symmetric chair form. The calculated strain energy for twist to chair process is 61.1 kJ mol^?1.     

Fragmentation mechanisms of oxidized peptides elucidated by SID, RRKM modeling, and molecular dynamics

The gas-phase fragmentation reactions of singly charged angiotensin II (AngII, DR⁺VYIHPF) and the ozonolysis products AngII+O (DR⁺VY*IHPF), AngII+3O (DR⁺VYIH*PF), and AngII+4O (DR⁺VY*IH*PF) were studied using SID FT-ICR mass spectrometry, RRKM modeling, and molecular dynamics. Oxidation of Tyr (AngII+O) leads to a low-energy charge-remote selective fragmentation channel resulting in the b ₄ +O fragment ion. Modification of His (AngII+3O and AngII+4O) leads to a series of new selective dissociation channels. For AngII+3O and AngII+4O, the formation of [MH+3O] ⁺ −45 and [MH+3O] ⁺ −71 are driven by charge-remote processes while it is suggested that b ₅ and [MH+3O] ⁺ −88 fragments are a result of charge-directed reactions. Energy-resolved SID experiments and RRKM modeling provide threshold energies and activation entropies for the lowest energy fragmentation channel for each of the parent ions. Fragmentation of the ozonolysis products was found to be controlled by entropic effects. Mechanisms are proposed for each of the new dissociation pathways based on the energies and entropies of activation and parent ion conformations sampled using molecular dynamics.     

Double-armed and tetra-armed cyclen-based cryptands

Double-armed and tetra-armed cyclen-based cryptands (1a–1d and 2) that bridge two aromatic rings by diethyleneoxy and triethyleneoxy units were prepared. The CSI-MS of 1:1 mixtures ([Ag⁺]/[ligand]) indicated that these new cryptands form 1:1 complexes with Ag⁺. The log K values for the interaction between Ag⁺ and 2 was greater than those of 1a–1d, double-armed cyclens (3a–3c and 4), and tetra-armed cyclen (5). The Ag⁺-ion-induced ¹H NMR spectral changes suggest that the Ag⁺–π interactions of the Ag⁺ complexes with the cryptands (1a–1d and 2) are stronger than those in Ag⁺/double-armed and tetra-armed cyclens. To visualise the Ag⁺?π interactions, the isosurfaces of the LUMO and HOMOs of the Ag⁺ complexes were calculated at the B3LYP/3–21G(*) theoretical level. The LUMO of the Ag⁺ ion is distorted by interaction with the HOMOs of the aromatic side arms. The calculations reveal Ag⁺?π interactions between the Ag⁺ ion and the aromatic side arms, and these are shown graphically.     

Complexes between disubstituted benzo-15-crown-5 ligands and sodium or potassium bromides

Stability constants have been determined with ion selective electrodes for complexes between sodium or potassium bromide in methanol with each of four crown ethers, benzo-15-crown-5 (Ia), dibromobenzo-15-crown-5 (Ib), dimethoxybenzo-15-crown-5 (Ic) and di-n-butoxybenzo-15-crown-5 (Id). Those for (Ib) were significantly lower than the others. The stability constants for complexes between sodium bromide and (Ia) and (Ib) in dimethylformamide (DMF) were found to be about one fifth of the corresponding values in methanol. The conductivity method was used to measure the ion pairing in methanol of sodium bromide alone and in the presence of (Ia), (Ib), or (Ic). Ion pairing is increased on complexation, the association constants being 3.3 mol^–1 dm³ for Na⁺ Br^– and 20–23 mol^–1 dm³ for Na(Ia–c)⁺ Br^–. The syntheses of compounds (Ic) and (Id) are described.     

Structural diversity and solid-state properties of CoII and ZnII coordination complexes with 5-aminonicotinate through metal direction

Zinc and cobalt 5-aminonicotinate (5-AN^–) complexes, Co(5-AN)₂(H₂O)₄ (1) and {[Zn(5-AN)₂](H₂O)}_n (2), have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction results indicate that coordination geometries are different (octahedral for Co^II and tetrahedral for Zn^II) and 5-AN^? adopts distinct binding modes (terminal in 1 and bridging in 2), forming a simple mononuclear coordination motif for 1 and a 2-D (4,4) coordination layer for 2. The higher-dimensional supramolecular architectures for both complexes are constructed via hydrogen bonding. Both complexes have been characterized by IR, microanalysis, and powder X-ray diffraction techniques and, their thermal stability and fluorescence have also been investigated.     

Tetrathiaoxa Macrocycles with Dibenzo-subunits: A Search for New Tl(I)- and Ag(I)-Selective Ionophores

Novel S⁴O ⁿ mixed donor macrocycles (1, n=1; 2, n=2) were synthesized by the coupling reactions of corresponding dichlorides with dithiols under high dilution conditions. Synthesis and crystal structures of Tl⁺ and Ag⁺ complexes, [Tl(2)⁺ and Ag(2)⁺], with macrocycle 2 are described. The electrode based on macrocycle 2 showed excellent potentiometric sensing ability for Tl⁺ and Ag⁺ ions. This remarkable sensing of the proposed electrode can be understood in terms of the synergy effect of a soft–soft acid–base interaction and π-coordination, especially for the Tl⁺ ion, which was observed from the crystal structure of the corresponding complex.     

Hydrogen-bonded mononuclear nickel(II) benzoate complexes: synthesis and structural studies

[Tp^Ph,MeNi(Cl)Pz^Ph,MeH] (1) has been synthesized by the reaction of hydrotris(3-phenyl-5-methyl-pyrazol-1-yl) borate [Tp^Ph,Me], NiCl₂ · 6H₂O and 3-phenyl-5-methyl-pyrazole [Pz^Ph,MeH]. The reaction of 1 with variously substituted sodium p–X–benzoates resulted in the formation of complexes of the type [Tp^Ph,MeNi(p–X–OBz)Pz^Ph,MeH] (X = H for 2, F for 3, Cl for 4, NO₂ for 5, Me for 6, OMe for 7, OH for 8, CHO for 9 and CN for 10). Single crystal X-ray studies suggest that all these complexes have a five-coordinate metal center and the benzoate groups are monodentate in a square pyramidal geometry. The X-ray studies also reveal that the uncoordinated oxygen atom of the benzoate forms intramolecular hydrogen-bonds with the NH group of the coordinated pyrazole. The substituents present on the benzoate ring are involved in different types of intermolecular interactions and the complexes exhibit different crystal packing. Complexes 2–10 were tested for superoxide dismutase activity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

八核茂铁-钌金属大环对钙离子的电化学和荧光识别(英)

The ruthenium unit was introduced into the redox-active molecular polygon to assembly new Ru-Fc metallocycles (Compound 1), in which the redox active (ferrocene) and fluoresecent (ruthenium) signaling subunits are directly attached by the putative cation-binding sites. The compound 1 displayed high selectivity for Ca^2 by electrochemical tests. The measurements of the fluorescence spectra on titration of 1 with Ca^2 , Li^ , Na^ , K^ , Mg^2 or Ba^2 ion indicate the unique ability of 1 to detect Ca^2 ions selectively.     

Synthesis,characterization and DNA nuclease activity of oxo-peroxomolybdenum(VI) complexes

The synthesis and structural characterization of two oxo-peroxo molybdenum(VI) complexes, [Mo(O)(O)₂(PAA)]^? (1) and [Mo(O)(O)₂(PAH)]^? (2), with phenylacetic acid (PAA) and 2-phenylacetylhydroxamic acid (PAHH) ligands have been accomplished. The coordination geometry of the oxo-peroxo molybdenum(VI) complexes is found to be pentagonal bipyramidal where, in both cases, the ligands are coordinated in bidentate fashion through oxygen atoms. The binding affinities of 1 and 2 with calf-thymus DNA (CT DNA) are determined using absorption spectroscopic measurements. The spectroscopic as well as cyclic voltammetric (CV) studies and viscosity measurements indicate that both complexes interact with CT DNA in the groove. The intrinsic binding constants are 5.2 × 10⁴ M^?1 and 7.3 × 10⁴ M^?1 for 1 and 2, respectively, from UV–vis studies. Complexes 1 and 2 show nuclease activity with plasmid DNA in the presence of H₂O₂. Concentration-dependent nuclease study suggests that 2 possesses higher ability to cleave plasmid DNA compared to 1. The experimental results of the binding of 1 and 2 with DNA are further supported by molecular docking studies.     

The Design of Ion Selective Macrocycles and the Solid-Phase Extraction of Ions Using Molecular Recognition Technology: A Synopsis

Abstract

We have combined organic synthesis and the study of cation complexation properties of the crown ethers in an effort to design and prepare macrocyclic ligands that will selectively bind specific cations.^1–3 The bis-phenol-containing diazacrown ethers allow a great number of possibilities for designing ion selectivity into macro-cyclic ligands. In these cases, the macrocyclic ligand can be varied as can the type and position of attachment of the phenolic group. Any of these variations can have profound effects on complexation properties. For example, ligand 1 (see Figure 1), where two 5-chloro-8-hydroxy-quinoline (CHQ) groups are attached through their positions 7, is selective for Mg²⁺ over other alkali and alkaline earth metal ions (see Table I).⁴ On the other hand, ligand 2, where the two CHQ groups are attached through their positions 2, exhibits remarkable selectivity for K⁺ and Ba²⁺ over all other metal ions studied. The chemical shifts of the CHQ protons in the ¹H NMR spectra of K⁺- and Ba²⁺- complexes with 2 shift significantly upfield in relation to the free ligand. These shifts are indicative of an overlap of the two CHQ substituents. Indeed, the crystal structure of the Ba²⁺-2 complex shows that Ba²⁺ is in the center of a pseudo-cryptand with the diazacrown forming two arms and the two overlapping CHQ groups forming the third.^4,5 This pseudo-cryptand formation accounts for the fact that the K⁺-2 and Ba²⁺-2 complexes are so stable in comparison to complexes of 2 with the other alkali and alkaline earth cations.     

13C, 15N and 113Cd NMR and Molecular Orbital Studies of Novel Bile Acid N-(2-aminoethyl)amides and Their Cd2+-complexes

Lithocholic acid N-(2-aminoethyl)amide (1) and deoxycholic acid N-(2-aminoethyl)amide(2) have been prepared and characterized by¹H, ¹³C and ¹⁵N NMR. The accurate molecular masses of 1 and 2 have been determined by ESI MS. The formation of the Cd²⁺-complexes (1+Cd and 2+Cd) in CD₃OD solution have been detected by ¹H,¹³C, ¹⁵N and ¹¹³Cd NMR. The ¹³C NMR chemical shift assignments of 1 and 2 and their Cd²⁺-complexes are based on DEPT-135 and z-GS ¹H,¹³C HMQC experiments as well as comparison with the assignments of the related structures. The ¹⁵N NMR chemical shiftassignments of the ligands and theirCd²⁺-complexes are based on z-GS¹H,¹⁵N HMBC experiments. ¹³C NMR chemical shift differences between 1and its 1:1 Cd²⁺-complex based on ab initiocalculations at Hartree-Fock SCI-PCM level using3-21G(d) basis set are in agreement with theexperimental shift changes observed onCd²⁺-complexation.     

Synthesis,spectral characterization,and evaluation of antimicrobial activity of O,O′-alkanediyl S-(N-phthalimidomethyl) dithiophosphates and zinc bis(O,O′-alkanediyl) dithiophosphates

The synthesis of novel dithiophosphate derivatives has been achieved. Two O,O′-alkanediyl S-(N-phthalimidomethyl) dithiophosphates and two Zinc bis(O,O′-alkanediyl) dithiophosphates are synthesized by an easy and facile chemical synthetic route. Zinc bis[O,O′-(2-methylpentane-2,4-diyl) dithiophosphate] L¹, Zinc bis[O,O′-(2-ethylhexane-1,3-diyl) dithiophosphate] L², O,O′-(2-methylpentane-2,4-diyl) S-(N-phthalimidomethyl) dithiophosphate L³ and O,O′-(2-ethylhexane-1,3-diyl) S-(N-phthalimidomethyl) dithiophosphate L⁴ are synthesized from the respective ammonium salts. Compounds L¹, L², L³, and L⁴ are characterized by (CHN) elemental analysis, ESI mass, FT-IR, ¹H, ¹³C, and ³¹P NMR techniques. The crystal structure of ammonium O,O′-(2-methylpentane-2,4-diyl) dithiophosphate is discussed. L¹, L², L³, and L⁴ were evaluated for antimicrobial activity. It was found that the phthalimide derivatives L³ and L⁴ showed much better antifungal potential against some species of fungus. The Zinc dithiophosphates L¹ and L² showed good antibacterial activity against Bacillus cereus and Escherichia coli.     

Copper(II) azide complexes with mono-anionic tridentate Schiff-base ligands: monomer versus dimer

Three new copper(II) complexes [CuL¹N₃]₂ (1), [CuL²N₃] (2) and [CuL³N₃] (3) with three very similar tridentate Schiff base ligands [HL¹?=?6-diethylamino-3-methyl-1-phenyl-4-azahex-3-en-1-one, HL²?=?6-amino-3-methyl-1-phenyl-4-azahex-3-en-1-one and HL³?=?6-amino-3-methyl-1-phenyl-4-azasept-3-en-1-one] have been synthesized and structurally characterized by X-ray crystallography. In complex 1 half of the molecules are basal-apical, end-on azido bridged dimers and the remaining half are square-planar monomers whereas all the molecules in complexes 2 and 3 are monomers with square-planar geometry around Cu(II). A competition between the coordinate bond and H-bond seems to be responsible for the difference in structure of the complexes.     

Synthesis,crystal structures,and infrared spectroscopy of a series of lanthanide phosphonoacetate coordination polymers

Hydrothermal reactions of lanthanide chloride, phosphonoacetic acid (H₂O₃PCH₂COOH), and water in the presence of HCl provide a series of lanthanide coordination polymers. FT-IR spectra confirm that there are three kinds of structures among seven complexes, {[Ln₂(O₃PCH₂CO₂)₂(H₂O)₃]?·?H₂O}_∞ (type I) (Ln?=?La^III for 1; Pr^III for 2; Nd^III for 3 and Eu^III for 4), [Ln(O₃PCH₂CO₂)(H₂O)₂]_∞ (type II) (Ln?=?Tb^III for 5), and [Ln(O₃PCH₂CO₂)(H₂O)₂]_∞ (type III) (Ln?=?Ho^III for 6 and Yb^III for 7). Complexes 1–5 show 2-D 4,4,5,5-connected (4⁴?·?6²)(4⁵?·?6)(4⁶?·?6⁴)(4⁸?·?6²) topology networks and 2-D 4-connected (4⁴?·?6²) topology networks and then are further linked into 3-D supramolecular networks by hydrogen-bonding interactions; 6 and 7 both exhibit a 3-D 4-connected (4²?·?6³?·?8) topology with 1-D dumbbell-shaped channels. The results indicate infrared spectroscopy is in accord with the result of single-crystal X-ray analysis.     

119Sn NMR Spectra of Some Carbohydrate Organotin Derivatives

Abstract

The ¹¹⁹Sn NMR spectra of several sugar-tin derivatives were recorded. The geometric and steric isomers of all of the organotin derivatives studied were easily differentiated by ¹¹⁹Sn NMR. The appropriate ¹¹⁹Sn resonances are: ca - 50 ppm for trans and ?60 ppm for cis vinyltin derivatives (1-3), ca 16 ppm for allyltins 4-6, and ca ?32 ppm for tin-carbinols 9 and 11. When the hydroxyl group in carbinol 9 was converted to an O-acetyl group, the chemical shift of ¹¹⁹Sn was shifted to ?22 ppm.