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Interactions of certain amino acids with some metal ions have significant consequences in biological systems. Metal ions can act as co-factors in the regulation of enzymatic reactions. Interactions of metal ions with amino acid side chains or with different organic complexes is also essential for many biological events. In this study, the stability constants of 1 : 1 : 1 ternary complexes of Cu(II) with 1,10-phenanthroline (Phen) as the primary ligand, and 2,2'-bipyridyl (Bpy) and some selected alpha-amino acids [(glycine (Gly), leucine (Leu), glutamine (Gln)] as secondary ligands, were identified in I=0.1 M ionic medium at t=(25+/-0.1) degrees C in aqueous solutions, by potentiometry. The protonation constants of the free ligands and the stability constants of the binary and ternary systems were also determined under the same experimental conditions. The protonation constants of all of the ligands and the stability constants of the formed complexes were evaluated by using the BEST computer program. The stabilities of the ternary complexes have been quantitatively compared with those of the corresponding binary complexes in terms of the some parameters. The concentration distributions of the complexes in solution were also evaluated. Species distributions as a function of pH reveal that the MAB ternary complexes predominate over a pH range, where M=Cu(II); A=Phen; B=Bpy, Gly, Leu and Gln.

Benzo[4,5]imidazo[1,2-c]quinazoline-6-carbonitriles are prepared in high yields via three new routes: (1) a Cu(OTf)2 (0-5 mol %) catalyzed hypervalent iodine [PhI(OTf)2] mediated oxidative coupling of 4-anilinoquinazoline-2-carbonitriles in neat trifluoroacetic acid (TFA) (2) a Pd(OAc)2 (10 mol %) or CuI (10 mol %) mediated nonoxidative coupling of 4-(2-bromoanilino)quinazoline-2-carbonitrile and (3) a nonoxidative Pd(Ar3P)3 [Ar = 3,5-(F3C)2C6H3] [aka Superstable Pd(0) Catalyst] (10 mol %) mediated intramolecular C-N cyclization of 3-(2-bromophenyl)-4-imino-3,4-dihydroquinazoline-2-carbonitriles. All new compounds are fully characterized. © 2015 American Chemical Society. 80 16 8329 8340 Cited By :6

TAS, MURAT/0000-0002-2879-6501; Vasilescu, Ioana/0000-0001-7219-5415; Junk, Peter/0000-0002-0683-8918 WOS: 000353316800034 Four new lanthanum(III) complexes of formulae [La(sac)(3)(Phen)(2)(H2O)(2)]center dot(Phen)(H2O)(2) (1), [La(sac)(3)(phen)(2)(H2O)(2)]center dot(Phen) (2). [12(sac)(2)(Phen)(H2O)(4)]center dot(sac) (3) and [La(sac)(2)(phen)(2)(H2O)(3)]center dot (sac)(phen)(H2O) (4) (phen = 1,10 phenanthroline, sac = saccharinate) have been synthesised and characterised by single crystal X-ray diffraction, IR, elemental analysis and thermogravimetric analysis. The binding mode of the sac anion was manipulated through the use of phen as structure inducer. In all four complexes the La(III) ion is in a nine-coordinate environment. The structures of 1 and 2 are similar, comprising of three sac anions coordinating in a monodentate fashion through the carbonyl O-atom, two bidentate phen and two water molecules coordinating directly to the same La(III) ion; a third, uncoordinated phen moiety also forms part of the unit cell. In addition, 1 is characterized by the presence of two crystallization water molecules which are absent in 2. In compound 3 the coordination sphere of La(III) is completed by a bidentate chelating sac through the N- and carbonyl O-atoms, a monodentate sac, a bidentate phen and four water ligands; a third, uncoordinated sac is also present in the crystal lattice. Compound 4 contains two bidentate phen, three water ligands and two monodentate O(carbonyl) sac ligands. The presence of three sac anions coordinating to the same lanthanide ion as well as a bidentate N-Ln-O chelating sac, confirmed by single crystal X-ray crystallography, is unprecedented for rare-earth saccharinates. (C) 2014 Elsevier Ltd. All rights reserved. James Cook University - Australia, Faculty of Medicine, Health & Molecular Science Internal grants scheme This work was financially supported by the James Cook University - Australia, Faculty of Medicine, Health & Molecular Science Internal grants scheme 2013. Crystal photography: Benjamin J. Crowley, Comparative Genomics Centre, James Cook University.

This study was implemented to determine the appropriate methods to be used in evaluation of iron (Fe) chlorosis in peach trees. For this purpose, three peach orchards having trees various visual chlorosis ratings were selected, and the leaf samples were collected during a 2-year period. The leaf samples were collected from two different positions in the annual shoots: 1) 5(th) 6(th), and 7(th) leaves in midpoint position of annual shoots and 2) extremity leaves of annual shoots. The leaf samples were only taken from the trees at 3 stages in the first year of the experiment to determine most convenient date of sampling. The experiment had 3 chlorosis categories (green, slightly chlorotic, and severely chlorotic) in the first year and 5 chlorosis categories in the second year (green, slightly chlorotic, slightly green, chlorotic, and severely chlorotic) with 3 replicates in each of the orchards. One M HCl, 1.5% o-phenanthroline, 0.5 M oxalic acid, and 0.1 M HCl methods in the fresh leaf samples, 1 M HCl, 0.5 M oxalic acid, 0.1 M HCl, and total Fe methods in oven-dried leaves were used for Fe analysis. The data were statistically analyzed by analysis of variance (ANOVA) and the least significant difference (LSD) values were calculated at the 5% level. According to the results obtained from the experiment, 1 M HCl and 1.5% o-phenanthroline in the fresh leaves and 1 M HCl in oven-dried leaves were well related to visual chlorosis ratings and chlorophyll content of the leaves as compared with other methods. The 1 M HCl method seemed to be the method of choice for producing a suitable index of Fe status of plants due to lower cost of analysis and ease in handling dry samples. Concentration of Fe determined by this method from green leaves at the midpoint position was generally greater than or equal to 30 mg kg(-1), which may be accepted as the critical index value for Fe in peach trees. Active Fe in the midpoint leaves was markedly and significantly higher than extremity leaves. To sample midpoint leaves may be recommended in determination of active Fe. There was no evidence to sample leaves on a certain date. This might have resulted from the wide range of sampling interval.

Reaction of [V(VI)OCl(2)(thf)(2)] with a bidentate nitrogen-donor ligand (L: phen=1,10-phenanthroline, 5-mephen=5-methyl-1,10-phenanthroline, bipy=2,2'-bipyridine, 5,5'-me(2)bipy=5,5'-dimethyl-2,2'-bipy) in methyl alcohol, in the presence of triethylamine, leads to the formation of hexameric [V(2) (IV)V(4) (V)] oxo-alkoxo-vanadates of the general formula [V(6)O(12)(mu(2)-OCH(3))(4)(L)(4)].x H(2)O [L=phen (1.4 H(2)O), 5-mephen (2.6 H(2)O), bipy (3.4 H(2)O), 5,5'-me(2)bipy (4.H(2)O)]. X-ray structure analysis of 1.2 H(2)O and 4.8 CH(3)OH revealed a pair of V(3)O(13)N(4) trimeric units sharing two corners, with a centrosymmetric planar V(6)-core. In addition, a fully oxidized V(V) species [V(V) (4)O(8)(OCH(3))(2)(mu(3)-OCH(3))(2)(5,5'-me(2)bipy)(2)].3 CH(3)OH (5.3 CH(3)OH) was isolated from the reaction mixture used for the synthesis of 4.H(2)O. The crystal structure of 5.3 CH(3)OH revealed a dicubane-like framework with two missing vertices. Electron paramagnetic resonance (EPR) and variable temperature magnetic susceptibility studies for the hexamers 1.4 H(2)O and 3.4 H(2)O showed the complete localization of the single 3d electrons on the V(IV) ions and unusual ferromagnetic interaction between the two paramagnetic vanadium(IV) ions separated by a distance of about 5.1 A. Furthermore, intermolecular antiferromagnetic interactions through pi-contacts of phenyl rings were observed for these species below 8 K. The ferromagnetic exchange coupling observed in the hexanuclear compounds 1.4 H(2)O and 3.4 H(2)O is also discussed using ab initio UHF calculations on a model compound. The value of the exchange coupling constant (3.7 cm(-1)) for this model compound, calculated using the broken symmetry approach, is in good agreement, both in sign and magnitude, with the experimental J values (6.00 cm(-1) for 1.4 H(2)O and 8.54 cm(-1) for 3.4 H(2)O).

The reaction of VCl(3) with 1,10-phenanthroline and a series of dipeptides (H(2)dip), having aliphatic as well as aromatic side chains, in methyl alcohol and in the presence of triethylamine affords vanadium(III) compounds of the general formula [V(III)(dip)(MeOH)(phen)]Cl. Aerial oxidation/hydrolysis of the vanadium(III) species gives their oxovanadium(IV) analogues of the general formula [V(IV)O(dip)(phen)]. X-ray crystallographic characterization of the [V(IV)O(dip)(phen)] compounds (where dip(2-)=Gly- L-Ala, Gly- L-Val and Gly- L-Phe) revealed that the vanadium atom possesses a severely distorted octahedral coordination and is ligated to a tridentate dip(2-) ligand at the N(amine) atom, the deprotonated N(peptide) atom and one of the O(carboxylate) atoms, as well as an oxo group and two phenanthroline nitrogen atoms. Circular dichroism characterization of the V(III)/V(IV)O(2+)-dipeptide compounds revealed a strong signal for the V(IV)O(2+) species in the visible range of the spectrum, with a characteristic pattern which may be exploited to identify the N(am), N(pep) and O(car) ligation of a peptide or a protein to V(IV)O(2+) center, and a weak Cotton effect of opposite sign to their vanadium(III) analogues. The visible spectra of the V(III)-dipeptide compounds revealed two d-d bands with high intensity, thus indicating that the covalency of the metal-donor atoms is significant, i.e. the vanadium d orbitals are significantly mixed with the ligand orbitals, and this is confirmed by the low values of their Racah B parameters. The high-intensity band of the V(IV)O(2+)-dipeptide compounds at approximately 460 nm implies also a strong covalency of the metal with the equatorial donor atoms and this was supported by the EPR spectra of these compounds. Moreover, the V(III)/V(IV)O(2+)-dipeptide complexes were characterized by EPR and IR spectroscopies as well as conductivity and magnetic susceptibility measurements.

A new bis-phenanthroline dicopper(II) complex has been synthesized and characterized by elemental analysis and spectroscopic methods. The molecular structure of the dinuclear Cu(II) complex [Cu2(?-CH 3COO)(?-H2O)(?-OH)(phen)2]2+ (phen = 1,10-phenanthroline) (1) was determined by single crystal X-ray diffraction technique. The coordination environment around each Cu(II) ion in complex 1 can be described as slightly distorted square pyramidal geometry. The distance between the Cu?Cu centers in the complex is found to be 2.987 �. The electronic, redox, phosphate hydrolysis, DNA binding and DNA cleavage have been studied. The antiproliferative effect of complex 1 was confirmed by the lactate dehydrogenase (LDH) enzyme level in MCF-7 cancer cell lysate and content media. The dicopper(II) complex inhibited the LDH enzyme as well as the growth of the human breast cancer MCF7 cell line at an IC 50 value of 0.011 ?g ml-1. The results strongly suggest that complex 1 is a good cancer therapeutic agent. Electrochemical studies of complex 1 showed an irreversible, followed by a quasi-reversible, one electron reduction processes between -0.20 to -0.8 V. Michaelis-Menten kinetic parameters for the hydrolysis of 4-nitrophenyl phosphate by complex 1 are kcat = 3.56 � 10-2 s-1 and KM = 4.3 � 10-2 M. Complex 1 shows good binding propensity to calf thymus DNA, with a binding constant value of 1.3 (�0.13) � 105 M-1 (s = 2.1). The size of the binding site and viscosity data suggest a DNA intercalative binding nature of the complex. Complex 1 shows efficient hydrolytic cleavage of supercoiled pBR322-DNA in the dark and in the absence of any external reagents, as demonstrated by the T4 ligase experiment. The pseudo-Michaelis-Menten kinetic parameters for DNA hydrolysis by complex 1 are kcat = 1.27 � 0.4 h-1 and KM = 7.7 � 10-2 M. � 2011 The Royal Society of Chemistry.

An indirect, sensitive spectrophotometric method for the assay of thiamine is described. The procedure is based on the formation of a mercaptide by thiamine, with a known excess of silver ions in a buffered medium of pH 9.0 +/- 0.1. The unreacted silver ions are determined by the formation of an ion-pair complex with 1,10-phenanthroline and 2,4,5,7-tetrabromofluorescein, which shows an absorption maximum at 550 nm. The absorbance is found to decrease linearly with increasing concentrations of thiamine, which is corroborated by the calculated correlation coefficient value of -0.998. The system obeys Beer's law for 0-25 micrograms of thiamine in an overall aqueous volume of 10 ml. The molar absorptivity and relative standard deviation (RSD) were calculated to be 7.8 x 10(4) l mol-1 cm-1 and 2.5% (n = 10), respectively. The proposed method was applied successfully to the determination of thiamine in pharmaceutical preparations. The reliability of the assay was established by parallel determination by the standard thiochrome method and recovery studies.