Experimental Determination of Third Derivative of the Gibbs Free Energy, <Emphasis Type=Italic>G</Emphasis> II: Differential Pressure Perturbation Calorimetry

We have been evaluating third derivative quantities of the Gibbs free energy, G, by graphically differentiating the second derivatives that are accessible experimentally, and demonstrated their power in elucidating the mixing schemes in aqueous solutions. Here we determine directly one of the third derivatives of G, the partial molar entropy-volume cross fluctuation density of 2-butoxyethanol (BE) in the BE–H₂O system, ^SV δ _BE . The difference of the heats of compression were directly determined using two identical cells and applying the same pressure change to both cells concurrently. Both cells are filled with sample solutions having a small appropriate difference in mole fraction. The results indicated that this method is feasible with the prior knowledge of the thermal expansivity of the solution to within a few per cent accuracy. If the volumes of the two cells are identical within the order of 0.01%, the method provides the required results to within 0.1% without the thermal expansivity data. This success opens a possibility of evaluating the fourth derivative graphically, which is expected to provide much more detailed information about the molecular processes in aqueous solutions.     

A highly selective and sensitive in vivo fluorosensor for zinc(II) without cytotoxicity

A highly selective and sensitive fluorescent Zn(2+) sensor, 2,6-bis(2-hydroxy-benzoic acid hydrazide)-4-methylphenol (1), was designed and synthesized. In aqueous THF (4 : 6 v/v) ligand 1 induces a 2 : 1 complex formation with respect to Zn(2+) at physiological pH. This probe features visible light excitation(390 nm) and emission (490 nm) profiles, excellent selectivity responses for Zn(2+)over other competing biological metal ions with K(d) < 1 pM(2), LOD < 1 ng L(-1) and about 680 fold enhancement in fluorescent intensity upon Zn(2+) binding. It also exhibits cell permeability and intracellular Zn(2+) sensing in A375 human melanoma cancer cell.     

Kinetics and mechanism of the oxidation of neutralized α-hydroxy acids by tris(pyridine-2-carboxylato)manganese(III)

The kinetics of oxidation of the neutralized -hydroxy acids: lactic, -hydroxyisobutyric, mandelic, benzilic and atrolactic acids by tris(pyridine-2-carboxylato)manganese(III) have been studied. The reactions were carried out in a Na(pic)-picH [Na(pic) = sodium salt of pyridine-2-carboxylic acid and picH = pyridine-2-carboxylic acid] buffer medium in the 4.89–6.10pH range. The oxidation rate was found to be independent of pH, and rate follows the order: benzilate > mandelate >atrolactate>lactate > -hydroxy isobutyrate. The oxidation products are MeCHO, Me2CO, PhCHO, Ph2CO and PhCOMe for the respective reactions. A mechanism is proposed involving intermediate formation of hepta-coordinated MnIII complexes in a fast step. The complexes then decompose to give free radicals and MnII in the rate determining step. The free radicals subsequently react with another molecule of the MnIII species to give the respective carbonyl compounds in a fast step.     

B → A Conformational Transition of DNA under the Influence of a Copper Thiolate,the Copper-cysteine: Biophysical,Spectroscopic and Gel Electrophoresis Studies

The interaction of calf-thymus DNA with copper(II)-cysteine (Cucys) was monitored by various biophysical methods. The interaction ratio was determined by the u.v.-spectrophotometric method, which was found to be 0.14. As the DNA 260 nm band remained insensitive followed by interaction with copper(II)-cysteine, the interaction ratio and the binding constant were determined by monitoring the 248 nm copper-cysteine charge-transfer (CT) band. Visible d–d spectra of Cucys proved that copper remained in the copper(II) state after interaction with DNA. The CD and thin film i.r. spectral studies revealed that there occurred B→A conformational transition of DNA when it was bound by copper-cysteine. Gel electrophoresis study confirmed the binding pattern.     

Information,Incentives and Decentralized Decision-Making in a Bayesian Framework

This paper examines the problem of choosing an organization structure for decision-making for two-level organizations under various information conditions. Decentralized decision-making (DDM), centralized decision-making with reporting by division (CDRD), and centralized decision-making (CDM) are considered. The information conditions pertain to the observability of states and actions. It is shown that if the party not making the decisions can infer the choice of action from the ex post knowledge of the state, then DDM and CDRD are essentially equivalent in that it is possible to devise optimal incentive schemes in both cases. If, however, the action choice cannot be inferred, then CDRD is at least as preferred as DDM by the centre (regulator). If ex post observation (or inference) of the state can be made only by the party making the decision, we show that the centre (regulator) prefers CDRD to DDM. For this case, we derive an incentive scheme which elicits truthful information from the division (regulated entity). Finally, the incentive schemes are applied to the problem of regulating an industry that pollutes the environment.     

Synthesis, characterization, and DNA binding of the biologically relevant novel cationic molybdenum(VI)–glutathione complex [Mo(GS)(Cl)(H2O)]Cl2

Abstract  

The complex [Mo(GS)(Cl)(H₂O)]Cl₂ (MoG) was synthesized in aqueous medium and its composition has been determined by elemental and thermogravimetric analysis. Binding modes were determined by ¹H NMR, ¹³C NMR, mass, and FT-IR spectrometry. The molecular formula was confirmed by mass spectral analysis. The molecular weight of the complex determined by the Rast camphor method also supports the formulation M _r = 525. This molecular formula demands the compound to be a 1:2 electrolyte, which is also supported by the conductance measurement, its value being 210 Ω⁻¹ cm². The compound is found to be diamagnetic, indicating that the molybdenum is in the +6 oxidation state (d⁰). The binding of MoG with calf thymus DNA was studied by spectroscopic titration. The interaction ratio was determined by monitoring the DNA 260 nm band as well as the S → Mo LMCT band of the complex observed at 225 nm. The interaction ratio calculated from the above studies was found to be 1:0.70 (DNA:MoG) in both cases, while the binding constant of DNA–MoG was found to be (4.8 ± 0.5) × 10⁵ M⁻¹. The binding constant data indicate that the binding nature is intercalative.     

Theoretical spectroscopic studies of InI and InI+

Relativistic configuration interaction calculations are carried out to study the electronic structure and spectroscopic properties of InI and InI⁺. Potential energy curves of the ground and a number of low‐lying states are constructed. Spectroscopic parameters of the bound states of both species are computed and compared with the experimental and other theoretical data. Effects of spin‐orbit coupling on the spectroscopic properties are studied. Because of the presence of the heavy atoms the effect is large. The spin‐orbit splitting of the ground state (X²Π) of InI⁺ is more than 8350 cm^?1. As a result of the strong spin‐orbit interaction between X²Π and A²Σ⁺ of InI⁺, the potential energy curve of A²Σ becomes repulsive. Radiative lifetimes for the spin‐forbidden transitions such as A³Π?X¹Σ and B³Π₁ ?X¹Σ of InI and spin‐allowed transitions such as B²Σ⁺?A²Σ⁺, C²Π?A²Σ⁺, and B²Σ⁺?X²Π are calculated. Vertical and adiabatic ionization energies of InI and the electric dipole moments of both the neutral and ionic species are estimated. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

A Thermally Induced Low-temperature Intramolecular Redox Reaction of bis(pyridine)silver(I) Permanganate and its hemipyridine Solvate

Among the known three pyridine complexes of silver permanganate, i.e. [Agpy₂]MnO₄ (1), [Agpy_2.25]MnO₄ or 7[Agpy₂]MnO₄[Agpy₄]MnO₄ (2) and [Agpy₂]MnO₄0.5py (3), compounds (1) and (2) were studied by means of thermal analysis and TG-MS methods. Presuming identical structural motifs for the Agpy₂MnO₄ blocks in (1) as it has been found in its solvate (3) by single-crystal diffraction, α-C–H...O–Mn H-bonded structures are responsible for a thermally induced low-temperature intramolecular redox reaction observed for the first time between the [Agpy₂]⁺ cation and permanganate anion.     

Oxidative Cleavage of S–S Bond During the Reduction of Tris(pyridine‐2‐carboxylato)manganese(III) by Dithionite in Sodium Picolinate–Picolinic Acid Buffer Medium

The reduction of tris(pyridine‐2‐carboxylato)manganese(III) by dithionite has been investigated within the temperature window 288–303 K and at pH range 5.22–6.10 in sodium picolinate–picolinic acid buffer medium. The reaction obeys the following stoichiometry: The reaction is described in terms of a mechanism that involves an initial complex formation between S₂O₄^2? and [Mn^III(C₅H₄NCO₂)₃] followed by S–S bond cleavage to give 2HSO₃^? and [Mn^II(C₅H₄NCO₂)₂(H₂O)₂] as the products via the formation of SO₂^●? radical anion. Kinetics and spectrophotometric evidences are cited in favor of the suggested mechanism. Thermodynamic parameters associated with the equilibrium step and the activation parameters with the rate‐determining step have been computed.