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1.
Energetic and structural properties of complexes formed from interaction between selenium analog of methimazole (MSeI) as an anti-thyroid drug and Mz+ (Li+, Na+, K+, Be2+, Mg2+ and Ca2+) cations have been investigated using B3LYP, M062X, PBE1PBE, and MP2 methods with 6-311++G(d,p) and 6-311++G(2d,2p) basis sets. Two planar and perpendicular complexes were predicted from interaction of MSeI and Mz+ cations. From the Gibbs free energy difference between the planar and perpendicular forms of MSeI–Mz+ complexes, it is found that the perpendicular forms are the predominant ones. In addition, the comparison of interaction energies shows that the order of energies increases in the following order: K+ < Na+ < Li+ < Ca2+ < Mg2+ < Be2+. The results of natural bond orbital analysis showed that the charge transfer occurs from MSeI to metal cations. The atom in molecule analysis shows that the charge density and its Laplacian at the Se–Mz+ bond critical point of the MSeI–M2+ complexes are greater than the MSeI–M1+ ones. Also, it was revealed that the Se–Mz+ interactions in perpendicular complexes of alkali and alkaline metal cations are electrostatic and partially covalent in nature, respectively.  相似文献   

2.
The geometries of the complexes of Li+, Na+, K+, Be2+, Mg2+, and Ca2+ metal cations with different possible 2,6-dithiopurine anions (DTP) were studied. The complexes were optimized at the B3LYP level and the 6-311++G(d, p) basis set. The interactions of the metal cations at different nucleophilic sites of various possible 2,6-dithiopurine anions were considered. It was revealed that metal cations would interact with 2,6-dithiopurine anions in a bicoordinate manner. In the gas phase, the most preferred position for the interaction of Li+, Na+, and K+ cations is between the N3 and S2 sites, while all divalent cations Be2+, Mg2+, and Ca2+ prefer binding between the N7 and S6 sites of the corresponding 2,6-dithiopurine. The influence of aqueous solvent on the relative stability of different complexes has been examined using the Tomasi’s polarized continuum model. The basis set superposition error (BSSE) corrected interaction energy was also computed for complexes. The AIM theory has been applied to analyze the properties of the bond critical points (electron densities and their Laplacians) involved in the coordination between 2,6-dithiopurine anions and the metal cations. It was revealed that aqueous solution would have significant effect on the relative stability of complexes obtained by the interaction of 2,6-dithiopurine anions with Mg2+ and Ca2+ cations. The effect of metal cations on different NH and CS stretching vibrational modes of 2,6-dithiopurine has also been discussed.  相似文献   

3.
Density functional theory calculation was carried out on cation‐π complexes formed by cations [M = H+, Li+, Na+, K+, Be2+, Mg2+, and Ca2+] and π systems of annelated benzene. The cation‐π bonding energy of Be2+ or Mg2+ with annelated benzene is very strong in comparison with the common cation‐π intermolecular interaction, and the bonding energies follow the order Be2+ > Mg2+ > Ca2+ > Li+ > Na+ > K+. Similarly, the interaction energies follow the trend 1‐M < 2‐M < 3‐M for all the metal cations considered. These outcomes may be due to the weak interactions of the metal cations with C? H and the interactions of metal cations with π in addition to the nature of a metal cation. We have also investigated on all the possible substituted sites, and find that the metal ion tends to interact with all ring atoms while proton prefers to bind covalently to one of the ring carbons. The binding of metal cations with annelated benzenes has striking effect on nuclear magnetic resonance chemical shifts using the gauge independent atomic orbital method. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009  相似文献   

4.

The complexes of Li+, Na+, K+, Be2+, Mg2+, and Ca2+ metal cations with [N3P3R4O(CH2CH2O)4] (R?=?H(1), NMe2(2), NC(NMe2)2(3)) PNP-lariat ethers were systematically studied in the gas phase by using density functional theory (DFT) B3LYP-D3/6-311+G(3df,2p)//B3LYP/6-31+G(d,p) method. The gas phase cation affinities were calculated to span the wide range between 64.2 and 496.1 kcal mol?1 in order K+?<?Na+?<?Li+?<?Ca2+?<?Mg2+?<?Be2+. The structural and electronic properties of 13 and their complexes were investigated and effects of electron-donor substituents were analyzed. The electron-donor substituents were found to promote the cation affinity. Sidearm coordinative interaction with the crown ether-complexed metal ion has been noticed. The nature of the metal–ligand interactions was investigated using Bader’s Quantum theory of atoms in molecule. It has been found that the Be2+–N bonds are partly covalent in nature while other coordinate bonds are of the electrostatic nature. The electron density at the bond critical points was found to be consistent with cation affinity. Natural bond orbital analysis was performed on the optimized geometries. The results showed that the stabilization interaction energies are caused by the donation of O/N lone pair electrons to the LP* orbitals of the metal cations. The amount of charge transfer follows the cation affinity order. The largest charge transfer and associated second-order perturbation stabilization energy were observed for Be2+ complexes.

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5.
Density functional theory calculations were performed at the B3LYP/6‐311++G(d,p) level to systematically explore the geometrical multiplicity and binding strength for the complexes formed by alkaline and alkaline earth metal cations, viz. Li+, Na+, K+, Be2+, Mg2+, and Ca2+ (Mn+, hereinafter), with 2‐(3′‐hydroxy‐2′‐pyridyl)benzoxazole. A total of 60 initial structures were designed and optimized, of which 51 optimized structures were found, which could be divided into two different types: monodentate complexes and bidentate complexes. In the cation‐heteroatom complex, bidentate binding is generally stronger than monodentate binding, and of which the bidentate binding with five‐membered ring structure has the strongest interaction. Energy decomposition revealed that the total binding energies mainly come from electrostatic interaction for alkaline metal ion complexes and orbital interaction energy for alkaline earth metal ion complex. In addition, the electron localization function analysis show that only the Be? O and Be? N bond are covalent character, and others are ionic character. © 2012 Wiley Periodicals, Inc.  相似文献   

6.
The structures and energies of complexes obtained upon interaction between glutathione (GSH) and alkali (Li+, Na+, K+), or alkaline earth metal (Be2+, Mg2+, Ca2+), or group IIIA (Al3+) cations were studied using quantum chemical density functional theory. The characteristics of the interactions between GSH and the metal cations at different nucleophilic sites of GSH were examined selecting systematically, both mono- and multi-coordinating were taken into account. The results indicated that the heteroatom of GSH, the radius and charge of metal ion, and the coordination number of the metal cation with the ligand played important roles in determining the stability of these complexes. Moreover, the intramolecular hydrogen migration in GSH could be promoted by the metal cations during coordination reaction. Furthermore, the Al3+ cation might catalyze the decarboxylation reaction and stimulate the formation of covalent bond between S atom and adjacent O atom of GSH.  相似文献   

7.
王宏贾建峰  武海顺 《中国化学》2006,24(11):1509-1513
Using quantum chemistry methods B3LYP/6-31++G(d,p) to optimize endohedral complexes X@(HBNH)12 (X=Li^0/+, Na^0/+, K^0/+, Be^0/2+, Mg^0/2+, Ca^0/2+, H and He), the geometries with the lowest energy were achieved. Inclusion energy, standard equilibrium constant, natural charge, spin density, ionization potentials, and HOMO-LUMO energy gap were also discussed. The calculation predicted that X=Na^0/+, K^0/+, Mg^0/2+, Ca^0/2+, H and He are nearly located at the center of (HBNH)12 cluster. Li^+ lies in less than 0.021 nm departure from the center. Li and Be^0/2+ dramatically deviate from the center. (HBNH)12 prefers to enclose Li^+, Be^2+, Mg^2+, and Ca^2+ in it than others. Moreover, M@(HBNH)12 (M=Li, Na, K) species are "superalkalis" in that they possess lower first ionization potentials than the Cs atom (3.9 eV).  相似文献   

8.
DFT (B3LYP functional) and MP2 methods using 6-311+G(2d,2p) basis set have been employed to examine the effect of ring fusion to benzene on the cation--π interactions involving alkali metal ions (Li+, Na+, and K+) and alkaline earth metal ions (Be2+, Mg2+ and Ca2+). Our present study indicates that modification of benzene (π-electron source) by fusion of monocyclic or bicyclic (or mixture of these two kinds of rings) strengthens the binding affinity of both alkali and alkaline earth metal cations. The strength of interaction decreases in the following order: Be2+ > Mg2+ > Ca2+ > Li+ > Na+ > K+ for any considered aromatic ligand. The interaction energies for the complexes formed by divalent cations are 4–6 times larger than those for the complexes involving monovalent cations. The structural changes in the ring wherein metal ion binds are examined. The distance between ring centroid and the metal ion is calculated for all of the complexes. Strained bicyclo[2.1.1]hexene ring fusion has substantially larger effect on the strength of cation--π interactions than the monocyclic ring fusion for all of the cations due to the π-electron localization at the central benzene ring.  相似文献   

9.
The cation influence on the water molecule in the Li+·H2O, Be2+·H2O, Mg2+·H2O and A13+·H2O complexes has been studied by means of quantum-mechanical ab initio calculations. A number of general trends are noted. (1) The calculated equilibrium water O-H distances increase with increasing binding energies, i.e. in the order Li+, Mg2+, Be2+, Al3+. The H-O-H angles differ by about ±1 ° from the calculated equilibrium angle for the free H2O molecule; the variation has no systematic trend. (2) The electron density redistribution accompanying the change in the internal H2O geometry in these complexes is considerably smaller than the redistribution brought about by the direct influence of the external field. (3) The harmonic O-H stretching force constant decreases with increased cation-water bonding. (4) The qualitative features of the density changes are very similar for the four complexes. The magnitudes of the interactions follow the relation Li+ < Mg2+ < Be2+ Al3+. An increased polarization of the H2O molecule occurs with electron migration from the H atoms towards the O atom and an accumulation of electron charge approximately at the centre of the Men+—O bond, especially in Be2+·H2O and A13+·H2O. An electron deficiency is found in the lone-pair region.  相似文献   

10.
《Chemical physics letters》2002,350(3-4):267-273
The aromatic cation tropylium, C7H7+, predicted at the MP2/6-31G** level, is capable of binding with metal cations Be2+ or Mg2+, forming M2+–C7H7+ complexes. The obstacle for their binding is almost electrostatic repulsion, and the binding is from polarization and charge transfer. The orbital interaction between the M2+ and C7H7+ is mainly the s–π and p–π interactions. Interestingly, Be2+ is possible to pass through the ring of C7H7+, while Mg2+ is not. The intrinsic IR band of the M2+–C7H7+ complex is below 600 cm−1, which results from the vibration of the M2+ along the normal axis of C7H7+.  相似文献   

11.
Cation–π complexes between several cations (Li+, Na+, K+, Be2+, Mg2+, and Ca2+) and different π-systems such as para-substituted (F, Cl, OH, SH, CH3, and NH2) benzene derivatives have been investigated by UB3LYP method using 6-311++G** basis set in the gas phase and the water solution. The ions have shown cation–π interaction with the aromatic motifs. Vibrational frequencies and physical properties such as dipole moment, chemical potential, and chemical hardness of these compounds have been systematically explored. The natural bond orbital analysis and the Bader’s quantum theory of atoms in molecules are also used to elucidate the interaction characteristics of the investigated complexes. The aromaticity is measured using several well-established indices of aromaticity such as NICS, HOMA, PDI, FLU, and FLUπ. The MEP is given the visual representation of the chemically active sites and comparative reactivity of atoms. Furthermore, the effects of interactions on NMR data have been used to more investigation of the studied compounds.  相似文献   

12.
In order to predict the extraction ability of 12-crown-4 for different metallic ions, the complexes [M(12-crown-4)] and [M(H2O)4] (where M=Li+, Na+, K+, Be2+, Mg2+, Ca2+, Cu2+ and Zn2+) were investigated by the density functional theory without restrictions for their geometry. The metal binding capability was evaluated using the binding energy, and the effect of nature of the metal on the binding properties was also studied. The results of the calculations showed that the coordination ability of a donor molecule towards different metal ions increased in proportion to their ionization potential. In addition, based on the extraction distribution coefficient, we found that 12-crown-4 can selectively extract Cu2+ and Be2+ ions from aqueous solutions of mixed cations. Obviously, the stability of complexes and the extraction power of extractants depend greatly on the nature of the metal ions. Calculation results from our study could be used to predict the extraction power of this crown ether and could play a guiding role in planning experiments.  相似文献   

13.
The interplay of metal ions with polysaccharides is important for the immune recognition in the lung. Due to the localization of beryllium associated diseases to the lung, it is likely that beryllium carbohydrate complexes play a vital role for the development of berylliosis. Herein, we present a detailed study on the interaction of Be2+ ions with fructose and glucose as well as simpler biomimetic ligands, which emulate binding motives of saccharides. Through NMR and IR spectroscopy as well as single-crystal X-ray diffraction, complemented by competition reactions we were able to determine a distinctive trend in the binding affinity of these ligands. This suggests that under physiological conditions beryllium ions are only bound irreversibly in glycoproteins or polysaccharides if a quasi ideal tetrahedral environment and κ4-coordination is provided by the respective biomolecule. Furthermore, Lewis acid induced conversions of the ligands and an extreme increase in the Brønstedt acidity of the present OH-groups imply that upon enclosure of Be2+, alterations may be induced by the metal ion in glycoproteins or polysaccharides. In addition the frequent formation of Be-O-heterocycles indicates that multinuclear beryllium compounds might be the actual trigger of berylliosis. This investigation on beryllium coordination chemistry was supplemented by binding studies of selected biomimetic ligands with Al3+, Zn2+, Mg2+, and Li+, which revealed that none of these beryllium related ions was tetrahedrally coordinated under the give conditions. Therefore, studies on the metabolization of beryllium compounds cannot be performed with other hard cations as a substitute for the hazardous Be2+.  相似文献   

14.
The energetic and structural optimized of a calix[4]arene with and without alkali-metal cations are presented with performance of various quantum chemical methods such as Hartree--Fock, second order Møller-Plesset perturbation theory, and density functional theory. The geometry optimizations have been carried out with the 3-21G (Li+--Cs+) and 3-21G(d,p) (Li+--K+) and the 3-21G basis sets for Cs+ and Rb+. Additional single-point energy ab initio calculations for Li+–K+ were carried out at HF/6--31G, HF/6-31G (d,p), HF/6--311G(d,p) for complexes of Li+ and Na+. The calculations were carried out to analyze the complexation of calix[4]arene with alkali metal cationic species (Li+, Na+, K+, Rb+, and Cs+). Assumption to isolate the effects of the aromatic core and cation-π interactions. Particular emphasis has been on conformational binding selectivity and the structural characterization of the complexes, the smaller cation as Li+ and Na+ has been placed in the lower rim's of the calix[4]arene's cavity. The large cations like K+, Rb+, and Cs+ take placed in upper rim and the endo (inclusive) complexation is driven by cation-π interactions, that reflect a superior interaction with two phenol rings. The endo complexation of Cs+ with calix[4]arene is in agreement with X-ray diffraction data. The binding modes of calixarene-cation systems are studied to involve cooperative effects between cation-π and electrostatic forces.  相似文献   

15.
Abstract

Thermodynamic quantities (log K, ΔH, and ΔS) for the interactions of a carbon-bridged cryptand with Li+, Na+, K+, Ca2+, Sr2+, Ba2+, and Pb2+ were determined at 25° C by calorimetric titration in aqueous solution. The cryptand forms complexes with Na+, Sr2+, Ba2+, and Pb2+ with log K ≤ 2. Complexation was not detected for Li+, K+, and Ca2+. Weak interactions with Li+ and K+ and a log K value of 2.4 for Na+ suggest that the cavity size of the cryptand is close to that of Na+ but too small for K+ and too large for Li+. The carbon-bridged cryptand selectively binds Sr2+ (log K = 3.2) over Ca2+ and Ba2+ by more than one order of magnitude.  相似文献   

16.
Complexones of a new class, viz., carboxy-functionalized calix[4]pyrrogallols, were synthesized. The per-O-(carboxymethyl)calix[4]pyrogallols obtained were established to exist in the (rel, cis, trans, trans)-configuration by 2D NMR spectroscopic data. According to the pH-potentiometric data, the interaction of these compounds with alkaline metal ions (Li+, Na+, K+, Cs+) and lanthanide ions (La3+, Gd3+, Lu3+) in a water—DMSO system produces 1 : 1 complexes. The specific features of complexation of per-O-(carboxymethyl)calix[4]pyrogallols, as compared to their acyclic analogs, with alkaline metal and lanthanide ions are due to the cooperative effect of donor groups preorganized on the calixarene matrix.  相似文献   

17.
Optimum geometries and stabilization energies are determined for complexes of H2O, NH3, CH4, C2H4, CO, and N2 with metal cations including Li+, Na+, K+, Rb+, Be2+, Mg2+, Ca2+, Zn2+, and Al3+, for the complex (HO)2PO 2 ...Mg2+ and for the complexes of water with F, Cl, and Br by SCF calculations employing the MINI-1 minimal gaussian basis sets. The Boys-Bernardi method was used to evaluate the superposition error. Comparison with the extended basis set results revealed that the MINI-1 set gives uniformly good results for a broad variety of ionic complexes and therefore should be preferred to other small basis sets.  相似文献   

18.
The structure and spectroscopic properties of the alkaline hydride BeH2+ ion have been investigated using an ab initio approach based on nonempirical pseudopotentials and parameterized l-dependent polarization potentials. The adiabatic potential energy curves and their spectroscopic constants for the ground and seventeen excited electronic states, dissociating into Be+(2s, 2p, 3s, 3p, 3d, 4s, 4p, and 4d) + H+ and Be2+ + H(1s and n = 2), of 2??+, 2??, and 2?? symmetries have been determined. As no experimental data are available, our results are discussed and compared with the few existing theoretical calculations. A very good agreement has been found with the previous theoretical data for the ground state; however many potential energy curves for the higher excited states are presented here, for the first time. Numerous avoided crossings between electronic states for 2??+ and 2?? symmetries have been localized and analyzed. Their existence is related to the interaction between the electronic states and to the charge transfer process between the two ionic systems Be2+H and Be+H+. In addition, we have calculated the vibrational energy level spacings of the bound electronic states. Furthermore, the adiabatic transition dipole functions from the X 2??+ and 22??+ states to the higher excited states of 2??+ and 2?? symmetries have been evaluated and compared with the available theoretical work. This study represents the necessary initial step towards the investigation of the charge transfer processes in collision between Be+-H+ and Be2+-H.  相似文献   

19.
Zusammenfassung Die Ionen der Alkali- und Erdalkalimetalle sowie von Ammonium wurden in 1,2-Propandiolcarbonat polarographisch untersucht; die Art der Grenzströme, die Diffusionsstromkonstanten, die Diffusionskoeffizienten, die Art der Abscheidungsvorgänge und die Halbwellenpotentiale gegen die gesättigte wäßrige Kalomelelektrode wurden bei 25,0o in 0,1m-Lösungen von Tetraäthylammoniumperchlorat in 1,2-Propandiolcarbonat bestimmt. Alle untersuchten Ionen geben je eine klare Reduktionswelle mit diffusionsbedingtem Grenzstrom, wobei die Elektrodenreaktion an der tropfenden Quecksilberelektrode für Na+, K+, NH4 +, Rb+, Cs+, Sr2+ und Ba2+ reversibel, für Li+, Be2+, Mg2+ und Ca2+ irreversibel abläuft. Analytische Simultanbestimmungen von Natrium und Kalium bzw. Calcium, Strontium und Barium sind auf Grund der Lage der Halbwellenpotentiale möglich. Der Einfluß von Wasser ist bis zu 1% unmerklich.
Polarographic investigations were carried out on alkali and alkaline earth metal ions, and on the ammonium ion, in propanediol-1,2-carbonate; the nature of the limiting currents, the diffusion current constants, the diffusion coefficients, the reversibility or irreversibility, and the half-wave potentials vs. aqueous saturated calomel electrode, were determined in 0,1m-solutions of tetraethylammonium perchlorate at 25.0o. Each of the ions investigated exhibits a well defined reduction wave with diffusion-controlled limiting current; the electrode reactions are reversible for Na+, K+, NH4 +, Rb+, Cs+, Sr2+, and Ba2+, and irreversible for Li+, Be2+, Mg2+, and Ca2+. The simultaneous analytical determination of sodium and potassium as well as of calcium, strontium, and barium is possible. The influence of water up to 1% is neglegibly small.
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20.
An efficient ion chromatographic (IC) method was developed for the simultaneous quantitative determination of Li+, Na+, NH4 +, K+, Cs+, Ca2+, Mg2+, Sr2+, Ba2+ and Be2+ in energy drinks, pharmaceutical and drinking water samples by non-suppressed conductometric detection. The separation of ten cations including ammonium was achieved using a cation-exchange column and low conductivity mobile phase. The mobile phase consisted of tartaric acid, dipicolinic acid and boric acid. The separation of the cations was completed in less than 18 min, with a flow rate of 1.2 mL min−1. The separation was not affected by the existence of cations Co2+, Cr3+, Cd2+, Cu2+, Bi3+, Ag+, Fe3+ and Zn2+ in concentrations up to 20 mg L−1. Using an injection volume of 20 μL the obtained detection limits were 0.003 mg L−1, 0.02 mg L−1, 0.01 mg L−1, 0.01 mg L−1, 0.10 mg L−1, 0.01 mg L−1, 0.02 mg L−1, 0.02 mg L−1, 0.003 mg L−1 and 0.1 mg L−1, for Li+, Na+, NH4+, K+, Cs+, Ca2+, Mg2+, Sr2+, Be2+ and Ba2+ respectively. The intra-day repeatability (RSD%, n=5) ranged from 1.1% to 4.8%, and the inter-day (n=5) between 1.8% and 5.4% respectively. The method was applied to the analysis of various bottled and tap water, pharmaceutical preparations and energy drinks commercially available.   相似文献   

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