A four-membered chelate complex of Cu(II) with creatinine

Abstract: The 1:1 proton transfer compound LH2, (creatH)+ (pydcH)−, has been prepared from the reaction of creatinine, creat, and dipicolinic acid, pydcH2, (2, 6- pyridinedicarboxylic acid) and characterized using IR, 1H and 13C NMR spectroscopy. The first coordination complex (creatH)[Zn(pydc)(pydcH)]·4H2O, was prepared using LH2 and zinc(II) nitrate, and characterized using IR, 1H and 13C NMR spectroscopy and single crystal X-ray crystallography. The crystal system is triclinic with space group with two molecules per unit cell. The unit cell dimensions are a = 8.085(2) A, b = 10.802(4) A, c = 13.632(4) A, α = 104.98(2)°, β = 90.31(2)° and γ = 92.55(3)°. The structure has been refined to a final value for the crystallographic R factor of 0.0381 based on 3003 reflections. The zinc atom is six-coordinated with a distorted octahedral geometry. The (pydc)2− and (pydcH)− units are almost perpendicular to each other. Extensive hydrogen bondings between carboxylate groups, (creatH)+ and water molecules throughout the zinc(II) complex as well as π–π stacking and ion pairing play important roles in stabilizing the corresponding lattices. The protonation constants of the building blocks of the pydcH2-creat adduct, the equilibrium constants for the reaction of (pydc)2− with creat and the stoichiometry and stability of the ZnII complex with LH2 in aqueous solution were accomplished by potentiometric pH titration. The solution studies support a self-associated (creatH)+(pydcH)− as the most abundant species at pH = 3.4. The stoichiometry of the crystalline complex (i.e. (creatH) [Zn(pydc)(pydcH)])and that of the most abundant species detected in solution were found the same.

Abstract: Data on the ability of the important bioligands creatinine and creatine to form various types of complexes with different metal ions are summarized. The crucial role of the nature of the reaction medium in complex formation with these ligands is emphasized. The conditions for obtaining paramagnetic oligomeric platinum complexes of the “platinum blue” type (resulting from multistep redox and coordination processes) are presented.

Abstract: Pt(II) and Pd(II) complexes with creatinine, C3H2N2(O)(CH3)NH2, were synthesized. Potentiometric and IR spectroscopic analyses were carried out. A model for the coordination of the ligands to the central atoms was confirmed by X-ray structural investigation of Pt(creat)4(ClO4)2. The compound [Pt(C4H7N3O)(ClO4)2] crystallizes in the monoclinic crystal system, space group C2/c, a = 15.748(5), b = 15.763(7), c = 24.843(8) A, β = 106.84(4)°, V = 5902 A3, Z = 8. The refinement of the structure by the least-squares method gave R = 0.051 and Rw = 0.054 for 1527 observed reflections with I > 2σ(I). The structure consists of Pt(creat)42+ complex cations, possessing approximate D2 symmetry and rotationally disordered perchlorate anions. The Pt atom is square-planarly coordinated by the endocyclic N atoms of four creatinine ligands. The PtN bond lengths range from 2.00(2) to 2.03(1) A and the NPtN angles from 88.4(9) to 91.8(8)°. The ligands are almost planar and tilted towards the PtN4-plane by 82.1(8)–93.5(9)°.

Abstract: In the present study, we report the synthesis of two green recoverable catalysts by covalent linking of the creatinine La and Pr complexes on an MCM-41 mesostructure with the commercially available materials and via a simple and inexpensive procedure. These heterogeneous catalysts were characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, N2 adsorption and desorption, inductively coupled plasma optical emission spectroscopy, and thermogravimetric analysis. The obtained mesostructures act as active and reusable catalysts for the oxidation of sulfides and oxidative coupling of thiols under neat conditions. More importantly, significant practical advantages of this environmentally friendly process include high efficiency, good reaction times, and convenient recovery and reusability for several times without any significant loss of activity of the catalyst.

Abstract: Objectives: It was our goal to develop a urine dipstick that could measure creatinine with a peroxidase reaction. The simultaneous measurement of albumin and creatinine permits the estimation of the 24-h albumin excretion, an important value in judging existing or likely development of renal failure. A highly sensitive dye-binding dipstick method for albumin exists, and a suitable dipstick for the assay for urine creatinine is described here. Methods: Copper-creatinine and iron-creatinine complexes have peroxidase activity. With 3,3′,5,5′-tetramethylbenzidine (TMB), and diisopropyl benzene dihydroperoxide (DBDH); the peroxidase activity of copper-creatinine and iron-creatinine complexes can be demonstrated. This reaction was used in the assay of urine creatinine either in solution or by a suitably impregnated urine dipstick. Results: Our method based on the peroxidase activity of the copper-creatinine complex has an analytical range for creatinine of 100 mg/L (0.884 mmol/L) to 3000 mg/L (26.52 mmol/L). The creatinine assay is free from most interfering compounds that may be present in urine. Hemoglobin is an interferent, and its effects can be reduced but not eliminated by the addition of 4-hydroxy-2-methyl quinoline. We do not recommend using the dipsticks when visible blood is present or if the dipstick blood test is positive. The copper-creatinine complex oxidizes ascorbic acid; however, we were able to modify the reaction conditions so that ascorbic acid at Discussion: With the simultaneous measurement of creatinine and albumin in urine, the albumin/creatinine ratio can be determined effectively reducing or eliminating the occasional false-negative and false-positive result in those with dilute or concentrated urines, respectively. The dipstick test for these analytes permits the simple identification of individuals with possible albuminuria and could serve well in a point-of-care setting.

Abstract: The properties of Cu(II) complexes of saturated macrocyclic ligands with square-pyramidal array were examined by cyclic voltammetry, electron spin resonance, visible absoption and magnetic circular dichroism spectroscopy. All ligands used with N4, N5, N6, N4S and N4O donor sets coordinated to Cu(II) to form a chromophore by the same donor set N4 at the equatorial plane. The values of λmax vs. E 1 2 and g∥ vs. 1/E 1 2 showed excellent linear correlations; however, the complexes containing O and S ligation exhibited marked deviations from the correlations. Of special interest is the fact that the physicochemical data of the 15N5–Cu(II) complex are substantially similar to those from the naturally occurring bleomycin–Cu(II) complex, in which the axially coordinated primary amino group plays a significant role for antitumor activity. With replacement of the axial N donor with the O and S donor, a marked positive shift was recognized in the E 1 2 values in the order of S > O > N. A positive shift of E 1 2 value, which is a feature of the apical S-donor in the square-pyramidal 15N4S–Cu(II) complex, was consistently seen for the glutathione–Cu(II) complex.

Abstract: Zinc, cadmium and mercury(II) complexes of creatinine of the composition M(Creat) 2 X 2 (X = Cl, Br or I) are prepared. The complexes are characterized by analytical and spectral methods. The increase in cyclic NH stretching frequency in the case of complexes (3350 cm −1 ) from that of the free ligand (3300 cm −1 ) suggested that secondary nitrogen is involved in coordination. The shift in the resonances of cyclic NH proton in the 1 H NMR and carbonyl and imine carbons in 13 C NMR when compared to the ligand indicated that cyclic nitrogen coordinates. Conductivity measurements in N, N-dimethylformamide suggested that the complexes are non-electrolytes. Thermal decomposition behaviour of the complexes is also discussed.

Abstract: Density ratios across shock waves in a 0.85 Kr+0.15 C2N2 mixture at an initial pressure of 50 mm Hg and room temperature, have been determined with an x‐ray densitometer as a function of shock velocity. The heat required to dissociate cyanogen into two CN radicals D(C2N2) has been determined to be 145±6 kcal/mole by comparing the experimental data with curves of density ratio vs shock velocity calculated as a function of D(C2N2). Dissociation energies of 174±3 kcal/mole for CN and 129±3 kcal/mole for HCN forming H and CN, and a heat of formation of 109±3 kcal/mole for CN, were obtained by the application of Hess's law to the appropriate chemical reactions using this value of D(C2N2) and the currently accepted values for the dissociation energy of nitrogen (225 kcal/mole) and the heat of sublimation of graphite (170 kcal/mole). The value of D(HCN) was confirmed by analogous density‐velocity measurements on shock waves in a 0.85 Kr+0.15 HCN mixture. A rate constant for the recombination of CN to form C2N2 at 2900°K was deduced from the variation of density with time behind the shock. The value obtained was of the order of 1×109 (mole/liter)—2 sec—1.