Probing the Stability and Structure of Metalloporphyrin Complexes with Basic Peptides by Mass Spectrometry

2005 ◽  
Vol 11 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Emily E. Jellen ◽  
Victor Ryzhov
Keyword(s):  
Gas Phase ◽  
Metal Ion ◽  
Basic Amino Acid ◽  
Quadrupole Ion Trap ◽  
Model Systems ◽  
Central Metal ◽  
Salt Bridges ◽  
Charge Solvation ◽  
The Stability ◽  
Basic Peptides

The stability and structure of non-covalent complexes of various peptides contatining basic amino acid residues (Arg, Lys) with metalloporphyrins were studied in a quadrupole ion trap mass spectrometer. The complexes of heme and three other metalloporphyrins with a variety of basic peptides and model systems were formed via electrospray ionization (ESI) and their stability was probed by energy-variable collision-induced dissociation (CID). A linear dependence for basic peptides and model compounds/metalloporphyrin complexes was observed in the plots of stability versus degrees of freedom and was used to evaluate relative bond strength. These results were then compared with previous data obtained for complexes of metalloporphyrins with His-containing peptides and peptides containing no basic amino acids. The binding strengths of Lys-containing peptide complexes in the gas phase was found to be almost as strong as that of Arg-containing complexes. Both systems showed stronger binding than His-containing peptides studied previously. To probe the structure of Arg and Lys non-covalent complexes (charge solvation versus salt bridges), two techniques, CID and ion–molecule reactions, were used. CID experiments indicate that the gas-phase complexes are most likely formed by charge solvation of the central metal ion in the metalloporphyrin by basic side chains of Arg or Lys. Results from the ion–molecule reaction studies are consistent with the charge solvation structure as well.

Preparation and Luminescent Properties of the La3+ Doped Tb3+-Hydroxyapatite

2014 ◽  
Vol 716-717 ◽  
pp. 32-35
Author(s):  
Wen Bin Liu ◽  
Adu ◽  
Yu Guang Lv ◽  
Li Li Yu ◽  
Yong Xiang Du ◽  
...  
Keyword(s):  
Rare Earth ◽  
Metal Ion ◽  
Chemical Properties ◽  
Earth Metal ◽  
Luminescent Properties ◽  
Central Metal ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
Terbium Ion ◽  
The Stability

In this paper, a rare earth metal terbium ion as the central metal ion, a nanohydroxyapatite powder of the lanthanum doped terbium was synthesis by precipitation with hydroxyapatite as ligand. The sample was characterized by infrared spectrum, fluorescence spectrum and X ray diffraction instrument, and the thermal properties and fluorescence properties, structure of powderes were discussed. A nanohydroxyapatite powder of the lanthanum doped terbium achieves the maximum luminous intensity, when the La3+ doping concentration of Tb3+ was HAP 5% (La3+ and Tb3+ mole fraction ratio) devices. Rare earth powder of the lanthanum doped terbium hydroxyapatite has the stability chemical properties, the luminescence properties and good biological activity, the rare earth powder has good luminescent properties can be used in preparation of a good light emitting device. At the same time a nanohydroxyapatite powder of the lanthanum doped terbium has good antibacterial property, can be used as antibacterial materials.

Properties and degradation of manganese(III) porphyrin thin films formed by high vacuum sublimation

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1515-1522
Author(s):  
Hsiang-Han Tseng ◽  
Michele Serri ◽  
Nicholas Harrison ◽  
Sandrine Heutz
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Metal Ion ◽  
High Vacuum ◽  
Bulk Diffusion ◽  
Central Metal ◽  
Vacuum Sublimation ◽  
Axial Ligands ◽  
Assembled Monolayers ◽  
The Stability

Manganese porphyrins are of interest due to the optical, electronic and magnetic properties of the central metal ion, coupled to the low bandgap of the polyaromatic ring. These attractive characteristics are harnessed in solutions or in ultra-thin films, such as, for example, self-assembled monolayers. However, for devices, thicker films deposited using a controlled and reproducible method are required. Here we present the morphological, structural, chemical and optical properties of manganese(III) tetraphenylporphyrin chloride (MnTPPCl) thin films deposited using organic molecular beam deposition, typically employed to process analogue molecules for applications such as organic photovoltaics. We find, using a combination of UV-vis and X-ray photoelectron spectroscopies, that the sublimation process leads to the scission of the Mn–Cl bond. The resultant film is a Mn(II)TPP:Mn(III)TPPCl blend where approximately half the molecules have been reduced. Following growth, exposure to air oxidizes the Mn(II)TPP molecule. Through quantitative analysis of the time-dependent optical properties, the oxygen diffusion coefficient (D) [Formula: see text] is obtained, corresponding to a slow bulk oxidation following fast oxidation of a 8-nm-thick surface layer. The bulk diffusion D is lower than for analogous polycrystalline films, suggestion that grain boundaries, rather than molecular packing, are the rate-limiting steps in oxidation of molecular films. Our results highlight that the stability of the axial ligands should be considered when depositing metal porphyrins from the vapor phase, and offer a solvent-free route to obtain reproducible and smooth thin films of complex materials for engineering film functionalities.

A mediated hydrogen bond in an α-hydroxycarboxyl group: X-ray structure of (R,R)-N-methyltartramic acid monohydrate and an ab initio study of model systems

1999 ◽  
Vol 55 (4) ◽  
pp. 617-625 ◽  
Author(s):  
Urszula Rychlewska ◽  
Agnieszka Szarecka ◽  
Jacek Rychlewski ◽  
Rafał Motała
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Gas Phase ◽  
Parent Compound ◽  
Model Systems ◽  
Ab Initio Study ◽  
Liquid Media ◽  
X Ray ◽  
The Stability ◽  
High Polarity

The crystal structure of (R,R)-N-methyltartramic acid monohydrate is presented and compared with that of the parent compound, (R,R)-tartaric acid. Despite some conformational differences between the two molecules the packing is very similar, as it is dictated by the carboxyl rather than the amide function. Particular attention is paid to a mediated three-centre hydrogen bond as one of the packing motifs involving the α-hydroxycarboxyl moiety. The stability and geometry of such structures in the gas phase and in solution are examined via theoretical ab initio methods using the RHF/6-311++G** and RHF/6-311++G**/Onsager models, respectively. Liquid media, in particular those of high polarity, are found to stabilize the structures considerably.

scholarly journals Polydopamine-Assisted Rapid One-Step Immobilization of L-Arginine in Capillary as Immobilized Chiral Ligands for Enantioseparation of Dansyl Amino Acids by Chiral Ligand Exchange Capillary Electrochromatography

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1800
Author(s):  
Yuanqi Gui ◽  
Baian Ji ◽  
Gaoyi Yi ◽  
Xiuju Li ◽  
Kailian Zhang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Ligand Exchange ◽  
Capillary Electrochromatography ◽  
Metal Ion ◽  
High Performance ◽  
Basic Amino Acid ◽  
Chiral Ligand ◽  
Central Metal ◽  
Dansyl Amino Acids ◽  
Chiral Ligand Exchange

Herein, a novel L-arginine (L-Arg)-modified polydopamine (PDA)-coated capillary (PDA/L-Arg@capillary) was firstly fabricated via the basic amino-acid-induced PDA co-deposition strategy and employed to constitute a new chiral ligand exchange capillary electrochromatography (CLE-CEC) method for the high-performance enantioseparation of D,L-amino acids (D,L-AAs) with L-Arg as the immobilized chiral ligand coordinating with the central metal ion Zn(II) as running buffer. Assisted by hydrothermal treatment, the robust immobilization of L-Arg on the capillary inner wall could be facilely achieved within 1 h, prominently improving the synthesis efficiency and simplifying the preparation procedure. The successful preparation of PDA/L-Arg coatings in the capillary was systematically characterized and confirmed using several methods. In comparison with bare and PDA-functionalized capillaries, the enantioseparation capability of the presented CLE-CEC system was significantly enhanced. Eight D,L-AAs were completely separated and three pairs were partially separated under the optimal conditions. The prepared PDA/L-Arg@capillary showed good repeatability and stability. The potential mechanism of the greatly enhanced enantioseparation performance obtained by PDA/L-Arg@capillary was also explored. Moreover, the proposed method was further utilized for studying the enzyme kinetics of L-glutamic dehydrogenase, exhibiting its promising prospects in enzyme assays and other related applications.

Is Lewis Acidity in Metal Dications Triggered by Solvent Shell Fluctuations?

2018 ◽  
Author(s):  
Tony Stace
Keyword(s):  
Experimental Data ◽  
Gas Phase ◽  
Metal Ion ◽  
Time Difference ◽  
Lewis Acidity ◽  
Water Molecules ◽  
Central Metal ◽  
Residence Times ◽  
Gas Phase Clusters ◽  
Mean Residence Times

Using experimental data collected on the stabilities of gas phase clusters consisting of metal dications in association with water molecules, a model is proposed to account for Lewis acidity. It is suggested that acidity is driven be fluctuations in the numbers of water molecules surrounding a metal ion, and that these fluctuations reduce numbers in the coordination shells to below those need to stabilise a +2 charge on the metal. The timescale on which these fluctuations are calculated to occur is approximately 6 orders of magnitude longer than any of the measure mean residence times of water molecules surrounding a central metal ion. This time difference reflects both the rarity of the event require to drive acidity and the extreme nature of some of the fluctuations.

Is Lewis Acidity in Metal Dications Triggered by Solvent Shell Fluctuations?

2018 ◽  
Author(s):  
Tony Stace
Keyword(s):  
Experimental Data ◽  
Gas Phase ◽  
Metal Ion ◽  
Time Difference ◽  
Lewis Acidity ◽  
Water Molecules ◽  
Central Metal ◽  
Residence Times ◽  
Gas Phase Clusters ◽  
Mean Residence Times

Using experimental data collected on the stabilities of gas phase clusters consisting of metal dications in association with water molecules, a model is proposed to account for Lewis acidity. It is suggested that acidity is driven be fluctuations in the numbers of water molecules surrounding a metal ion, and that these fluctuations reduce numbers in the coordination shells to below those need to stabilise a +2 charge on the metal. The timescale on which these fluctuations are calculated to occur is approximately 6 orders of magnitude longer than any of the measure mean residence times of water molecules surrounding a central metal ion. This time difference reflects both the rarity of the event require to drive acidity and the extreme nature of some of the fluctuations.

scholarly journals Coordination properties of N,O-carboxymethyl chitosan (NOCC). Synthesis and equilibrium studies of some metal ion complexes. Ternary complexes involving Cu(II) with (NOCC) and some biorelevant ligand

2012 ◽  
Vol 10 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Azza Shoukry ◽  
Wafaa Hosny
Keyword(s):  
Metal Ions ◽  
Stability Constants ◽  
Metal Ion ◽  
Ternary Complexes ◽  
Central Metal ◽  
Magnetic Studies ◽  
Complex Formation Equilibria ◽  
Equilibrium Studies ◽  
The Stability ◽  
Solid Complexes

AbstractIn the present study, the acid-base equilibria of N,O-carboxymethy chitosan abbreviated as (NOCC), is investigated. The complex formation equilibria with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The stability constant values of the binary and ternary complexes formed in solution were determined and the binding centers of the ligands were assigned. The relationships between the properties of the studied central metal ions as ionic radius, electronegativity, atomic number, and ionization potential, and the stability constants of the formed complexes were investigated in an effort to give information about the nature of chemical bonding in complexes and make possible the calculation of unknown stability constants. Cu(II), Ni(II), and U(VI) complexes with NOCC are isolated as solid complexes and characterized by conventional chemical and physical methods. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. The ternary copper(II) complexes involving NOCC and various biologically relevant ligands containing different functional groups, as amino acids and DNA constituents are investigated. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated.

scholarly journals MOLECULAR STRUCTURE AND VIBRATION SPECTRA OF PIVALIC ACID

2018 ◽  
Vol 59 (7) ◽  
pp. 17
Author(s):  
Alexander E. Pogonin ◽  
Oleg A. Pimenov ◽  
Yuriy A. Zhabanov
Keyword(s):  
Molecular Structure ◽  
Ir Spectra ◽  
Gas Phase ◽  
Metal Ion ◽  
Density Functional ◽  
Pivalic Acid ◽  
Basis Sets ◽  
Potential Energy Distribution ◽  
Central Metal ◽  
Vibrational Modes

The metal carboxylates such as metal pivalates (salts of the pivalic acid (CH3)3CCOOH) attract a great interest as most promising precursors for chemical vapor deposition (CVD) technology. The possibility to use these substances in the CVD technology is specified by their good thermal stability and high volatility. For modeling of chemical reactions with metal pivalates in the gas-phase and the data on molecular structure will be very useful, in particularly information about effect of central metal ion to geometry of pivalic ligands. In the frame of this task the structures of metal pivalate molecules and pivalic acid (H(piv)) in a gas phase should be finding. The aim of present work is theoretical investigation of the geometry and IR-spectrum of H(piv) using density functional theory (DFT) methods. All calculations were performed using the Gaussian 03 program. The optimization of geometry and quadratic force field calculations were carried out using DFT functionals B3LYP, PBE, PBE0 and BP86 with correlation-consistent triple-ζ valence cc-pVTZ basis sets for O, C, and H. Appropriate assignment of vibrational modes was carried out by the potential energy distribution (PED) analysis among internal coordinates using the SHRINK program. According to DFT computations, the H(piv) molecule has an equilibrium structure of Cs symmetry with Гvib=26A'+19A''. The theoretical and experimental IR-spectra are satisfactorily agreed. The comparison of the ten intensities of highest bands in spectra allowed determining linear correlation between peaks position in experimental and modeling IR-spectra. It should be note the complicated composition of vibrational modes.

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