Numerical studies of the cubic non-linear Schrodinger equation

In this paper, we are concerned with the problem of applying cubic non-polynomial spline functions to develop a numerical method for obtaining approximation for the solution for cubic non-linear Schrodinger equation. The truncation error of the method is theoretically analyzed. Using the Von Neumann method, the proposed method is shown to be unconditionally stable. The linearization technique is carried out to solve the system and to prove that the method is unconditionally stable. Two numerical examples are included to illustrate the practical implementation of the proposed method.     

A review on the synthesis of heteroannulated quinolones and their biological activities

Molecular Diversity - The quinoline scaffold has become an important construction motif for the development of new drugs. The quinolones and their heteroannulated derivatives have high importance...     

Thioimidazolate versus pyrazolate-zinc(II)-bound hydroxo complex as structural model for the active site of hydrolytic enzyme: the crystal structure of the inclusion complex TtZn–O–C6H4–p-NO2, Tt?=?hydrotris(N-xylyl-2-thioimidazolyl)borate

The reaction of the tripod ligand hydrotris(N-(2-methylphenyl)-2-thioimidazol-1-yl)borate, Tt with zinc(II) chloride yielded the chloro complex [TtZn–Cl] 1. The hydrolytic reactivity of its hydroxo complex [TtZn–(μ-OH)ZnTt]Cl 2 towards p-nitrophenyl acetate was hampered due to the formation of the stable phenolate complex [TtZn–O–Ar–p-NO₂] 3 as a product inhibition. The X-ray structure analysis of complex 3 was determined and showed that its Zn[S₃O] coordination sphere includes three thione donors from the ligand Tt and one oxygen donor from the hydrolysed product p-nitrophenolate in an ideally tetrahedral arrangement around the zinc(II) centre.     

Electronic Structure of Six-Membered N-Heterocyclic Carbenes and Its Heavier Analogues: Reactivity of the Lone Pair versus the Exocyclic Double Bond

Electronic structure of the six-membered N-heterocyclic carbene, silylene, germylene, and stannylene having an exocyclic double bond at the C3 carbon atom as well as the relative reactivity of the lone-pair on the divalent group 14 element and the exocyclic double bond have been studied at the BP86 level of theory with a TZVPP basis set. The geometrical parameters, NICS values, and NBO population analysis indicate that these molecules can be best described as the localized structure 1X(a), where a trans-butadiene (C1-C2-C3-C4) unit is connected with diaminocarbene (N1-X-N2) via N-atoms having a little contribution from the delocalized structure 1X(b). The proton affinity at X is higher than at C4 for 1C, and a reverse trend is observed for the heavier analogues. Hence, the lone pair on a heavier divalent Group 14 element is less reactive than the exocyclic double bond. This is consistent with the argument that, even though the parent six-membered carbene and its heavier analogues are nonaromatic in nature, the controlled and targeted protonation can lead to either the aromatic system 3X having a lone pair on X or the nonaromatic system 2X with readily polarizable C3-C4 π-bond. The energetics for the reaction with BH(3) and W(CO)(6) further suggest that both the lone pair of Group 14 element and the exocyclic double bond can act as Lewis basic positions, although the reaction at one of the Lewis basic positions in 1X does not considerably influence the reactivity at the other. The protonation and adduct formation with BH(3) and W(CO)(5) at X lead to nonaromatic systems whereas similar reactions at C4 lead to aromatic systems due to π-bond polarization at C3-C4. The degree of polarization of the C3-C4 π-bond is maximum in the protonated adduct and reduces in the complexes formed with BH(3) and W(CO)(5).     

Thieno[2,3‐d]pyrimidines in the Synthesis of New Fused Heterocyclic Compounds of Prospective Antitumor and Antioxidant Agents (Part II)

Diethyl azodicarboxylate and 3,4,5,6‐tetrachloro‐1,2‐benzoquinone react with cyclopentano‐ and cycloheptano‐fused thienopyrimidines to form the oxidative dimer of the starting material via S—S bond formation. Reaction of two equivalents of 2,2′‐(cyclohexa‐2′,5′‐diene‐1,4‐diylidene)dimalononitrile with thienopyrimidines afforded 3‐(4′,4′‐dicyanomethylene‐cycloalka[a]‐2,5‐dienyl)‐4‐oxo‐6,7,8,9‐tetrahydro‐5H‐cyclo‐hepta[4,5]‐[1,3]thiazolo[3,2‐a]‐thieno[2,3‐d]pyrimidin‐2‐ylidene‐2‐dicarbonitriles. The thioenopyrimidines react with 2‐[1,3‐dioxo‐1H‐inden‐2(3H)‐ylidene]malononitrile to produce 1,3,5′‐trioxo‐1,3,3′,5′‐tetrahydrospiro‐(indene‐2,2′‐thiazolo[2,3‐b]‐cycloalkyl[b]‐thieno[2,3‐d]pyrimidine)‐3′‐carbonitriles. However, the reaction of thienopyrimidines with 2,3‐dicyano‐1,4‐naphthoquinone proceeded to afford the fused cycloalkyl‐thieno form of naphtho[1,3]thiazolo[3,2‐a]thieno[2,3‐d]pyrimidine‐6.7,12‐triones. Reaction of 2‐hydrazino‐5,6,7,8‐tetrahydrobenzo[b]thieno[2,3‐d]pyrimidine‐4(1H)‐one with dimethyl acetylenedicarboxylate and ethyl propiolate, respectively, afforded cyclohexano‐fused (Z)‐dimethyl 2[(E)‐4‐oxo‐3,4‐dihydrothieno[2,3‐d]pyrimidine‐2(1H)‐ylidene)hydrazono]succinate and thieno‐pyrimidinotriazine. Both oxidative dimers of thienopyrimidines showed high inhibition of Hep‐G2 cell growth compared with the growth of untreated control cells. Moreover, the cycloheptano‐fused thiazinothienopyrimidine indicates a promising specific antitumor agent against Hep‐G2 cells because its IC₅₀ is < 20 μM.     

A Convenient Synthesis and a Nuclear Magnetic Resonance Spectroscopic Study of a β-D Linked Trisaccharide

The building block derivatives of the monosaccharide, O-(3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-D-glucopyranosyl) trichloroacetimidate (1), and the disaccharide α, α-trehalose, 2′,3′6′-tri-O-benzoyl-α-D-glucopyranosyl-2,3,4,6-tetra-O-benzoyl-α-D- glucopyranoside (2) were coupled to produce trisaccharide 3. A detailed n.m.r. analysis [ ¹H, ¹³C, ¹³C-¹H correlation, and 2D ¹H-¹H correlation experiment (COSY)] was used for the structural elucidation of the building blocks 1, 2 and the trisaccharide product 3.     

Synthesis,magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 4–formylantipyrine N(4)-antipyrinylthiosemicarbazone

4–Formylantipyrine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic, n.m.r., e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate (NS) or tridentate ligands (ONS), either in the thione or thiolato form. Stereochemistries are proposed for the complexes on the basis of both spectral and magnetic studies.     

Treatment of radioactive and industrial liquid wastes by Eichornia crassipes

Chemical factors such as pH, concentration and temperature affecting the removal of UO₂ ²⁺, Th⁴⁺, Fe³⁺, Cu²⁺, Pb²⁺,Cd²⁺, Ni²⁺, MnO₄ ^- and phenol by Eichornia crassipes aquatic plant from their solutions were examined. Maximum uptake of ions by Eichornia crassipes occurred at pH 4 to 6±0.5 at 25±3 °C. An initial rapid uptake phase for the first 6 hours followed by a slower near linear one was observed. One gram of Eichornia crassipes can accumulate about 25 mg UO₂ ²⁺, 5 mg Th⁴⁺, 30 mg Fe³⁺, 10 mg MnO₄ ^-, 15 mg Cu²⁺, 1.0 mg Pb²⁺, 1.5 mg Ni²⁺, 0.7 mg Cd²⁺ and or 25 mg of phenol.     

Synthesis and Identification of New N,N-Disubstituted Thiourea,and Thiazolidinone Scaffolds Based on Quinolone Moiety as Urease Inhibitor

Synthesis of thiazolidinone based on quinolone moiety was established starting from 4-hydroxyquinol-2-ones. The strategy started with the reaction of ethyl bromoacetate with 4-hydroxyquinoline to give the corresponding ethyl oxoquinolinyl acetates, which reacted with hydrazine hydrate to afford the hydrazide derivatives. Subsequently, hydrazides reacted with isothiocyanate derivatives to give the corresponding N,N-disubstituted thioureas. Finally, on subjecting the N,N-disubstituted thioureas with dialkyl acetylenedicarboxylates, cyclization occurred, and thiazolidinone derivatives were obtained in good yields. The two series based on quinolone moiety, one containing N,N-disubstituted thioureas and the other containing thiazolidinone functionalities, were screened for their in vitro urease inhibition properties using thiourea and acetohydroxamic acid as standard inhibitors. The inhibition values of the synthesized thioureas and thiazolidinones exhibited moderate to good inhibitory effects. The structure−activity relationship revealed that N-methyl quinolonyl moiety exhibited a superior effect, since it was proved to be the most potent inhibitor in the present series achieving (IC₅₀ = 1.83 ± 0.79 µM). The previous compound exhibited relatively much greater activity, being approximately 12-fold more potent than thiourea and acetohydroxamic acid as references. Molecular docking analysis showed a good protein−ligand interaction profile against the urease target (PDBID: 4UBP), emphasizing the electronic and geometric effect of N,N-disubstituted thiourea.