Authors:Silvia Piero, Andrea Melchior, Davide Menotti, Marilena Tolazzi, and Anders Døssing
An investigation on the thermodynamics of complex formation between Ag(I) ion and two tripodal ligands tris[(2-pyridyl)methyl]amine
(TPA) and 6,6′-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2′-bipyridine (BTPA) has been carried out in the aprotic solvents
dimethylsulfoxide (DMSO) and dimethylformamide (DMF) by means of potentiometry and titration calorimetry. The results for
TPA are compared with those already obtained for other aliphatic tripodal polyamines. In general, the TPA ligand forms complexes
less stable than 2,2′,2″-triaminotriethylamine (TREN) and tris(2-(methylamino)ethyl)amine (Me3TREN) as a result of the combination of higher structural rigidity of TPA and lower σ-donor ability of pyridinic moieties
with respect to primary and secondary amines. The same trend is found if the stability of Ag(I) complex with TPA is compared
with that of tris(2-(dimethylamino)ethyl)amine (ME6TREN), despite the pyridinic nitrogen is formally a tertiary one. Theoretical calculations run to explain the reasons of this
weaker interaction indicate that this difference is due to solvation, rather than to steric or σ-donor effects. The ligand
BTPA is able to form bimetallic species whose relative stability is largely influenced by the different solvation of Ag(I)
ion in DMSO and DMF rather than by the difference in the dielectric constants of these two media.
Authors:D. Czakis-Sulikowska, J. Radwańska-Doczekalska, A. Czylkowska, M. Markiewicz, and A. Broniarczyk
New mixed-ligand complexes with empirical
(M(II)=Co, Cu), Ni(2-bpy)3L24H2O
(where 2-bpy=2,2’-bipyridine, 2,4’-bpy=2,4’-bipyridine; L=HCOO– ) have been
obtained in pure solid-state. The complexes were characterized by chemical
and elemental analysis, IR and VIS spectroscopy, conductivity (in methanol
and dimethylsulfoxide). The way of metal-ligand coordination discussed. The
formate and 2,4’-bpy act as monodentate ligands and 2-bpy as chelate
ligand. The new complexes with ligand isomerism were identified. During heating
the complexes lose water molecules in one or two steps. Thermal decomposition
after dehydration is multistage and yields corresponding metal oxides as final
products. A coupled TG-MS system was used to analysis principal volatile thermal
decomposition (or fragmentation) products of Ni(2,4’-bpy)2(HCOO)22H2O under dynamic air or argon atmosphere.
In the present communication we report on the radiation induced grafting of methyl methacrylate (MMA) onto irradiated isotactic
polypropylene film (IPP) by Peroxidation method to prepared grafted membrane (IPP-g-MMA). The radioactive isotope 60Co was used as the source of gamma radiation. A plausible mechanism of grafting has been proposed. Optimum conditions pertaining
to maximum percentage of grafting were evaluated as a function of different reaction parameters such as radiation dose, inhibitor
concentration, monomer concentration, reaction time and reaction temperature respectively. Maximum percentage of grafting
(85%) was obtained at [radiation dose] = 25 kGy, [inhibitor concentration] = 0.04 wt%, [MMA] = 6 wt%, [Reaction Temperature] = 60 °C
in a [Reaction time] of 120 min. The evidence of grafted membrane was characterized by Fourier transform infrared spectroscopy,
Atomic force microscopy method, Scanning electron microscopy which indicates that MMA has been grafted onto IPP. Hydrolysis
of the grafted membranes in 1 N NaOH transformed ester groups of the grafted membranes to carboxylic acid and hydroxyl groups
to form hydrolyzed grafted membranes. Hydrolyzed grafted membranes were investigated for their swelling behavior. Swelling
properties of the hydrolyzed grafted membranes were performed in different solvents such as water, N,N-dimethylformamide (DMF)
and dimethylsulfoxide (DMSO). Maximum percentage swelling value of IPP-g-MMA was observed in pure DMSO, followed by DMF and
Authors:Małgorzata Jóźwiak, Adam Bald, and Andrzej Jóźwiak
The thermodynamic functions of complex formation of benzo-15-crown-5 ether (B15C5) and sodium cation (Na+) in acetone–water mixtures at 298.15 K have been calculated. The equilibrium constants of B15C5/Na+ complex formation have been determined by conductivity measurements. The enthalpic effect of complex formation has been measured
by the calorimetric method. The complexes are enthalpy-stabilized but entropy-destabilized in acetone–water mixtures. The
effects of hydrophobic hydration, preferential solvation of B15C5 by a molecule of water and acetone, respectively and the
solvation of Na+ on the complex formation processes have been discussed. The calculated thermodynamic functions of B15C5/Na+ complex formation and the effect of benzene ring on the complex formation have been compared with analogous data obtained
in dimethylsulfoxide–water mixtures. The effect of carbonyl atom replacement in acetone molecule by sulphur atom (DMSO molecule)
on the thermodynamic functions of complex formation has been analysed.
New mixed-ligand complexes with empirical formulae M(4-bpy)L21.5H2O (M(II)=Mn, Co), Ni(4-bpy)2L2 and Cu(4-bpy) L2H2O (where: 4-bpy=4,4'-bipyridine, L=CC L2HCOO-) have been isolated in pure state. The complexes have been characterized by elemental analysis, ir spectroscopy, conductivity
(in methanol, dimethylformamide and dimethylsulfoxide solutions) and magnetic and x-ray diffraction measurements. The Mn(II)
and Co(II) complexes are isostructural. The way of metal-ligand coordinations discussed. the ir spectra suggest that the carboxylate
groups are bonded with metal(II) in the same way (Ni, Cu) or in different way (Mn, Co). The solubility in water is in the
order of 19.4010-31.8810-3ł mol dm-3ł. During heating the hydrate complexes lose all water in one step. The anhydrous complexes decompose to oxides via several
intermediate compounds. A coupled TG-MS system was used to analyse the principal volatile products of obtained complexes.
The principal volatile products of thermal decomposition of complexes in air are: H2O2+, CO2+, HCl+, Cl2+, NO+ and other.
The heat effects of the reactions of formation of ethylenediamine-copper(II) complexes were determined calorimetrically in
mixtures of water with ethanol, acetone and dimethylsulfoxide. The results were interpreted in terms of the enthalpies of
transfer (ΔtH0) of the complex former, the ligand and the complex ion from water to binary solvents.
In water—DMSO mixtures, the ΔtH0 values for copper(II) and complex ions were found to change in similar ways, and their contributions to the reaction heat
effects compensate each other to a large extent. Thus, the reaction enthalpy change due to solvent composition variation is
caused mainly by the changes in ligand solvation enthalpies.
In aqueous ethanol and acetone solutions, the changes in ΔtH0 for all reagents influence the heat effect equally.
Authors:Mihaela Badea, Rodica Olar, Dana Marinescu, Valentina Uivarosi, Teodor Nicolescu, and Daniela Iacob
A series of new complexes with mixed ligands of the type RuLm(DMSO)nCl3·xH2O ((1) L: oxolinic acid (oxo), m = 1, n = 0, x = 4; (2) L: pipemidic acid (pip), m = 2, n = 1, x = 2; (3) L: enoxacin (enx), m = 2, n = 1, x = 0; (4) L: levofloxacin (levofx), m = 2, n = 2, x = 8; DMSO: dimethylsulfoxide) were synthesized and characterized by chemical analysis, IR and electronic data. Except oxolinic
acid that behaves as bidentate, the other ligands (quinolone derivatives and DMSO) act as unidentate. Electronic spectra are
in accordance with an octahedral stereochemistry. The thermal analysis (TG, DTA) in synthetic air flow elucidated the composition
and also the number and nature of both water and DMSO molecules. The TG curves show 3–5 well-separated thermal steps. The
first corresponds to the water and/or DMSO loss at lower temperatures followed either by quinolone thermal decomposition or
pyrolisys at higher temperatures. The final product is ruthenium(IV) oxide.
Authors:Z. Bokor, T. Müller, M. Bercsényi, L. Horváth, B. Urbányi, and Á. Horváth
Experiments were carried out on sperm cryopreservation of two European percid fish species, the pikeperch
and the Volga pikeperch
. Two experiments were conducted on pikeperch sperm. In the first, the effects of three extenders (Glucose, KCl, Sucrose) and two cryoprotectants (dimethyl-sulfoxide: DMSO, methanol: MeOH) were tested on motility and fertilization. In the second, the effects of two dilution ratios (1: 1, 1: 9) and two cryoprotectants (DMSO, MeOH) on hatching were investigated. In the experiment on Volga pikeperch the suitability of using cryopreservation for fertilization was investigated. In the first experiment on pikeperch the highest post-thaw motility (28 ± 21%) and fertilization rate (43 ± 12%) was found with DMSO as cryoprotectant in combination with Glucose extender. In the second, the highest hatch rate (41 ± 22%) was observed with MeOH as cryoprotectant and 1: 1 sperm dilution ratio, however no significant difference was found among the results. In the experiment on Volga pikeperch hatch rates with cryopreserved sperm (60 ± 2%) did not significantly differ from the control (60 ± 6%). Contamination of sperm with urine seems to be a key problem in the success of sperm cryopreservation of these species.
Authors:Vladimir Barannikov, Sabir Guseynov, and Anatoliy Vyugin
Enthalpies of solution of dibenzo-18-crown-6 at infinite dilution have been measured in tetrachloromethane, benzene, chloroform,
pyridine, acetone, dimethylformamide, dimethylsulfoxide, acetonitrile, benzyl alcohol and propylene carbonate at temperature
of 298.15 K. Values for enthalpy of solvation and solute–solvent interaction in the solvents were determined. Correlation
of enthalpies of solvation with the enthalpy of cavity formation and contribution for the different types of solute–solvent
interaction was obtained. In benzene, tetrachloromethane, pyridine, DMF and DMSO polar conformer of DB18C6 dominates. Its
effective dipole moment amounts to 3.7 D. Conformation dynamics of the solute reduces the effective polarity of such solvents
as acetone, chloroform and propylene carbonate in which population of polar conformer of dibenzo-18-crown-6 decreases. Condensation
of two benzene rings to 18-crown-6 results in increasing molecule polarity and exothermic contribution of dipole–dipole interaction
in polar solvent media. The specific interaction with acetonitrile and chloroform becomes weaker from 18-crown-6 to dibenzo-18-crown-6.