Sharif Digital Repository

Objectives: The aim of this study was to assess and compare the crystalline structures of both powder and bulk human dental enamel by X-ray diffraction analysis (XRD). Methods: The buccal surfaces of 60 selected noncarious third molars were divided into two groups of powdered and bulk enamel specimens. To prepare enamel powders, the enamel tissues were ground and powdered manually using a mortar and pestle. For bulk samples, the enamel slabs were sectioned using a low-speed diamond saw. The crystalline structures of samples were analyzed by XRD, and the obtained data were analyzed. The values of the lattice parameters were obtained using the equation of hexagonal crystalline structures. The... 

The synthesis and structures of two new octadentate, Schiff-base calixpyrrole macrocycles are presented in which modifications at the meso-substituents (L1) or the aryl spacer between the two pyrrole-imine donor compartments (L2) are introduced. The outcomes of these changes are highlighted in the structures of binuclear Pacman complexes of these macrocycles, [M2(L1)] and [M2(L 2)]. Both palladium and cobalt complexes of the fluorenylmeso- substituted macrocycle H4L1 adopt rigid, but laterally twisted geometries with enclosed bimetallic microenvironments; a consequence of this spatial constraint is an exo-exo-bonding mode of pyridine in the dicobalt complex [Co2(py)2(L1)]. In contrast, the... 

13C chemical shieldings and 14N and 2H electric field gradient (EFG) tensors of L-alanylglycine (L-alagly) dipeptide were calculated at RHF/6-31++G and B3LYP/6-31++G levels of theory respectively. For these calculations a crystal structure of this dipeptide obtained from X-ray crystallography was used. Atomic coordinates of different clusters containing several L-alagly molecules were used as input files for calculations. These clusters consist of central and surrounding L-alagly molecules, the latter forming short, strong, hydrogen bonds with the central molecule. Since the calculations did not converge for these clusters, the surrounding L-alagly molecules were replaced by glycine... 

A five-coordinated Fe(III) complex with the distorted trigonal bipyramidal configuration was synthesized by reactions of FeCl36H2O and 2-(2′-hydroxyphenyl)oxazoline (Hphox) as a bidentate ON donor oxazoline ligand. Complex [Fe(phox)2Cl] was fully characterized, including by single-crystal X-ray structure analysis. DFT calculations were accompanied with experimental results in order to obtain a deeper insight into the electronic structure and vibrational normal modes of complex. Oxidation of sulfides to sulfoxides in one-step was conducted by this complex as catalyst using urea hydrogen peroxide (UHP) in mixture of CH2Cl 2/CH3OH (1:1) under air at room temperature. The results show that using... 

The significant role of protein nanoparticle interactions in nanomedicine and nanotoxicity is emerging recently through the identification of the nanoparticles (NP) protein (biomolecule) corona. The dynamic layer of proteins and/or other biomolecules adsorbed to the nanoparticle surface determines how a NP interacts with living systems and thereby modifies the cellular responses to the NP. Ehrenberg and co-workers used cultured endothelium cells as a model for vascular transport of polystyrene NP with various functional groups, which showed that the capacity of the various NP surfaces to adsorb proteins was indicative of their tendency to associate with cells. The quantification of the... 

In this work, two important opioid antagonists, naltrexone and oxycodone, were prepared from thebaine and were characterized by IR, 1H NMR and 13C NMR spectroscopy. Moreover, computational NMR and IR parameters were obtained using density functional theory (DFT) at B3LYP/6-311++G* * level of theory. Complete NMR and vibrational assignment were carried out using the observed and calculated spectra. The IR frequencies and NMR chemical shifts, determined experimentally, were compared with those obtained theoretically from DFT calculations, showed good agreements. The RMS errors observed between experimental and calculated data for the IR absorptions are 85 and 105 cm-1, for the 1H NMR peaks are... 

A new binuclear copper(ii) complex, namely [Cu2L(pz)(DMSO)], where L = 2,6-bis[(2-phenoxy)iminomethyl]-4-methylthiophenolate(3-) and pz = pyrazolate ligand, has been synthesized by a one-pot synthesis involving copper(ii) acetate monohydrate, the S-protected ligand precursor 2-(N,N-dimethylthiocarbamato)-5-methylisophthalaldehyde di-2′-hydroxy anil, (I), and pyrazole, in which a metal-promoted S-deprotection reaction occurs during the formation of the complex. This was characterized by routine physicochemical studies, single crystal X-ray diffraction and electron paramagnetic resonance (EPR) techniques. The structure analysis reveals that there are copper centres in two different... 

Herein, functionalized spiro[indoline-3,5′-pyrazolo[1,2-a]pyridazine]-7′-carbonitrile containing two contiguous chiral stereocenters was efficiently synthesized in a satisfactory yield (up to 91% yield) and with excellent diastereoselectivity. We have reached this satisfactory yield by DABCO-catalyzed [3+3] annulation reactions of an isatin N,N′-cyclic azomethine imine 1,3-dipole with a Knoevenagel intermediate in dichloromethane (DCM) as solvent at ambient temperature; this was an entirely new strategy for creating one quaternary stereogenic center at the position-3 of an oxindole structure using an abnormal tandem Michael addition, N-cyclization, and a unique approach via the azomethine... 

Herein, functionalized spiro[indoline-3,5′-pyrazolo[1,2-a]pyridazine]-7′-carbonitrile containing two contiguous chiral stereocenters was efficiently synthesized in a satisfactory yield (up to 91% yield) and with excellent diastereoselectivity. We have reached this satisfactory yield by DABCO-catalyzed [3+3] annulation reactions of an isatin N,N′-cyclic azomethine imine 1,3-dipole with a Knoevenagel intermediate in dichloromethane (DCM) as solvent at ambient temperature; this was an entirely new strategy for creating one quaternary stereogenic center at the position-3 of an oxindole structure using an abnormal tandem Michael addition, N-cyclization, and a unique approach via the azomethine...