Sharif Digital Repository

A simple bidentate ligand, 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3- oxazine, was readily prepared with a two-step synthesis. Two novel complexes of Pd(II) and Cu(II) with this (N,O) oxazine ligand have been prepared and the molecular structures of these complexes have been confirmed by X-ray structure analysis, NMR, IR and UV-Vis spectroscopy. These complexes efficiently catalyze the Heck reaction of aryl halides with olefins at 120 °C in 8 h. The reaction conditions for the Heck coupling of iodobenzene with styrene was optimized by varying the amount of the catalyst, reaction temperature, solvent and exogenous base  

Two enantiomerically pure chiral dioxidomolybdenum(VI) complexes (1 and 2) of the type [MoO2L] (L = dianionic, tetradentate ONNO-ligand) were synthesized and investigated in enantioselective oxidation reactions. The solid-state structures of complex 1 and 2, determined via single-crystal X-ray diffraction analysis revealed two fundamentally different coordination geometries: a C1-symmetric cis-β isomer (Λ-1), and a C2-symmetric cis-α isomer (Δ-2). In both cases, only one of the two possible helical enantiomers (Λ- or Δ-helix) was formed. The complexes were examined as precatalysts in the epoxidation of the challenging prochiral substrate trans-stilbene, using either tert-butyl hydroperoxide... 

Herein we describe the synthesis and characterization of the first platinum(IV) metal-organic cage [(Me3PtIV)8(byp)12](OTf)8 (2), in which the organometallic moieties trimethylplatinum(IV) (PtMe3) occupied the corners of a cubane structure and 4,4′-bipyridine ligands used as linkers. The first-principles density functional theory calculations showed that the highest occupied molecular orbitals were localized on the PtMe3 moieties, while the lowest unoccupied molecular orbitals were distributed on the organic linkers. © 2021 American Chemical Society  

The structural and computational studies of a new molybdenum tetracarbonyl complex of 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i]-[1,4,8,11]tetraazacyclotetradecine, a 14-membered tetraazaannulene macrocyclic ligand, Me2Ph2H2TAA, were carried out by X-ray crystallography and density functional and natural bond orbital (NBO) theories. The complex showed an interesting intermolecular C-H⋯O hydrogen bond which was supported by n → π∗ interaction, forming a one-dimensional extended chain along the b-axis. Interesting intramolecular C-H⋯π and very short σ → π∗ (C-H⋯CO) interactions stabilized the twisted geometry of the coordinated ligand. © 2019 The Royal Society of Chemistry 2019  

The structural and computational studies of a new molybdenum tetracarbonyl complex of 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i]-[1,4,8,11]tetraazacyclotetradecine, a 14-membered tetraazaannulene macrocyclic ligand, Me2Ph2H2TAA, were carried out by X-ray crystallography and density functional and natural bond orbital (NBO) theories. The complex showed an interesting intermolecular C-H⋯O hydrogen bond which was supported by n → π∗ interaction, forming a one-dimensional extended chain along the b-axis. Interesting intramolecular C-H⋯π and very short σ → π∗ (C-H⋯CO) interactions stabilized the twisted geometry of the coordinated ligand. © 2019 The Royal Society of Chemistry 2019  

Reaction of the known cycloplatinated (II) complexes [PtAr(C^N)(SMe2)], in which Ar=p–MeC6H4 or p–MeOC6H4 and C^N= 2-phenylpyridinate (ppy) or benzo[h]quinolinate (bhq), with 0.5 equivalent of the bidentate phosphine ligand 1,1′–bis(diphenylphosphino)acetylene, dppac, in acetone at room temperature gave the symmetrical binuclear cycloplatinated(II) complexes [Pt2Ar2(C^N)2(μ–dppac)], 1–4, in which dppac acts as a bridging bidentate ligand. All the complexes were fully characterized using multinuclear (1H, 31P and 195Pt) NMR spectroscopy and the complex [Pt2(p–MeC6H4)2(ppy)2(μ–dppac)], 1, was further identified by single crystal X-ray structure determination. Additional information about the... 

ApolipoproteinD (ApoD) is a human glycoprotein from the lipocalin family. ApoD contains a conserved central motif of an 8-stranded antiparallel β-sheet, which forms a beta-barrel that can be used for transport and storage of diverse hydrophobic ligands. Due to hydrophobic nature of ApoD, it has been difficult to generate a recombinant version of this protein. In the present work, we aimed at the production of ApoD in the robust Pichia pastoris expression system. To this end, the ApoD gene sequence was synthesized and subcloned for expression in the yeast host cells. Following integration of the ApoD gene into the yeast genomic region using homologous recombination, the ApoD recombinant... 

Two unique heteronuclear Schiff base complexes of Cu(II), [{Cu(L)Na(ClO4)}2(μ-H2L)] (1) and Ni(II), [{Ni(L)Na(BF4)}2(μ-H2L)] (2) were synthesized and characterized by different spectroscopic methods as well as X-ray crystallography. The Schiff base ligand (H2L) was synthesized from the condensation meso-1,2-diphenyl-1,2-ethylenediamine with 3-methoxysalicylaldehyde. The 3d metal ions in these complexes have been accommodated by the inner N2O2 compartment of the Schiff base ligand, while the O2O′2 outer compartment has accommodated the Na(I) ion (O and O′ denote the phenolic and methoxy oxygen atoms, respectively). Besides, a Schiff base ligand has doubly bridged the M(II)/Na(I) moieties via... 

This paper presents synthesis and photophysical investigation of a very rare type of the ReI diimine complexes, [Re(diimine)(CO)3(OPR3)]+, R = Ph, Cy; diimine – phenanthroline and neocuproine, containing monodentate (unsupported) phosphine oxide ligands. The obtained compounds have been structurally characterized in solid phase by using XRD crystallography, which revealed unusual distortions in the pseudo octahedral rhenium environment, which may be ascribed to intramolecular interligand (phosphine oxide – diimine) interaction rather than to crystal packing effect. Optimization of the ground state structure of these molecules with the DFT method also confirmed intramolecular origin of the... 

This is the first study of samarium powder catalyzed cyanation reaction of aryl halides, bearing electron-withdrawing and electron-releasing substituents, in the presence of NaCN to afford corresponding benzonitriles in high yields. This protocol takes the advantage of being done in the absence of additive, ligand and precious transition metals such as palladium. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim  

The combined action of ultraviolet irradiation and microwave heating onto acetonitrile solution of [Re((Formula presented.))(CO)3(NCMe)]OTf ((Formula presented.) =phenantroline and neocuproine) afforded cis,trans-Re((Formula presented.))(CO)2(NCMe)2]+ acetonitrile derivatives. Substitution of relatively labile NCMe with a series of aromatic N-donor ligands (pyridine, pyrazine, 4,4’-bipyridine, N-methyl-4,4’-bipyridine) gave a novel family of the diimine cis,trans-[Re((Formula presented.))(CO)2(L)2]+ complexes. Photophysical studies of the obtained compounds in solution revealed unusually high absorption across the visible region and NIR phosphorescence with emission band maxima ranging from... 

Two new potentially heptadentate N4O3 Schiff base ligands {N[(CH2)3NCH(2-OH-3,5-t-Bu2C 6H2)]3} (H3L1) and {N[(CH2)3NCH(2-OH-3,5-t-Bu2C6H 2)]2 [(CH2)2-NCH(2-OH-3,5-t-Bu 2C6H2)]} (H3L2) were synthesized and characterized by various spectroscopic methods. The heptadentate N4O3 Schiff bases, H3L1 and H 3L2, were derived from the condensation reaction of two tripodal tetraamine ligands, tris(3-aminopropyl)amine and (2-aminoethyl)-bis(3- aminopropyl)amine with 3 equiv. of 3,5-di-tert-butylsalicylaldehyde, respectively. The neutral gadolinium(III) and samarium(III) complexes, [Ln(L)], of these bulky ligands and also a gadolinium(III) complex of a previously known ligand,... 

In this paper, we consider the bacterial point-to-point communication problem with one transmitter and one receiver by considering the ligand receptor binding process. The most commonly investigated signalling model, referred to as the Level Scenario (LS), uses one type of a molecule with different concentration levels for signaling. An alternative approach is to employ multiple types of molecules with a single concentration level, referred to as the Type Scenario (TS). We investigate the trade-offs between the two scenarios for the ligand receptor from the capacity point of view. For this purpose, we evaluate the capacity using numerical algorithms. Moreover, we derive an upper bound on the... 

A comparative investigation of the interaction of Cu(II) with a series of 15- to 19-membered mixed-donor dibenzo-substituted macrocyclic ligands, each incorporating an O2N2-donor set, has been carried out using UV-Visible studies in methanol. Although a ring size effect has been reported for a related series of Ni(II) complexes, no such metal ion discrimination has been reported for Cu(II) in terms of its binding constants with 14- to 17-membered macrocycles. Employing Job's method of continuous variation established 1:1 stoichiometry for the interaction between Cu(II) and 1-5. From UV-Visible studies applying the Benesi-Hildebrand equation, the binding constants (K) of Cu(II) with 1-5 were... 

Some cis-dioxomolybdenum (VI) complexes with tridentate Schiff base ligands derived from salicylaldehyde and aminophenols, aminoalcohol or o-aminobenzenethiol were examined as catalysts for epoxidation of different aliphatic and aromatic olefins, with tert-butyl hydroperoxide as oxidant. All complexes exhibited high activity and selectivity for epoxidation of aliphatic substrates during a short time period (95% conversion of cyclooctene after 30 min). The epoxide yield increased with the nucleophilic character of olefin. The catalysts activation strongly depends on the reaction temperature and nature of the solvent. Epoxidation of olefins by these catalysts is inhibited by ligands or... 

The noticeable enhancement in fluorescence emission of O2N2-donor naphthodiaza-crown macrocyclic ligand (L) in the presence of Hg2+ was observed in which the fluorescence quantum yield of free ligand L as well as L/Hg2+ complex were found to be as 0.29 and 0.49, respectively. The observed ultra-low limit of detection (LOD) for Hg2+ by L was determined as low as 1.0 × 10−11 M in water. A 1:1 stoichiometry was also established for L/Hg2+ together with a binding constant KBH = 66,543 by employing fluorescence spectrophotometry. The competition experiments on L/Hg2+ demonstrated highly selective detection of Hg2+ in the presence of the library cations. A two path mechanism for detection of metal... 

In this study, adsorption of important pollutant cations on the surface of graphitic carbon nitride (g-C3N4) was investigated by density functional theory. The calculations indicated that N6 cavity surrounded by triazine units is the most probable adsorption site on this surface. The structural optimizations also predicted a planar surface for Cr3+, and Ni2+/g-C3N4 systems while the structure of the surface for other systems indicated a considerable distortion with strong dependency on the cation size. Also, g-C3N4 surface exhibited the high adsorption energies for Cr3+, As3+, and Sb3+ ions in the gas phase. However, formation energies of the metal-aquo complexes of these cations indicated...