String Non(anti)commutativity for Neveu-Schwarz Boundary Conditions

The appearance of non(anti)commutativity in superstring theory, satisfying the Neveu-Schwarz boundary conditions is discussed in this paper. Both an open free superstring and also one moving in a background antisymmetric tensor field are analyzed to illustrate the point that string non(anti)commutativity is a consequence of the nontrivial boundary conditions. The method used here is quite different from several other approaches where boundary conditions were treated as constraints. An interesting observation of this study is that, one requires that the bosonic sector satisfies Dirichlet boundary conditions at one end and Neumann at the other in the case of the bosonic variables X ^μ being antiperiodic. The non(anti)commutative structures derived in this paper also leads to the closure of the super constraint algebra which is essential for the internal consistency of our analysis.     

Synthesis of sulfur‐containing heterocycles: spiropyrimidinetriones,thioxopyrimidinediones, pyrazolidinediones,and isoxazolidinediones—part ii

1‐Aroyl‐2‐styrylsulfonylethene is the precursor for 4,4‐dimethoxycarbonyl‐2′,5‐diaryl‐3‐(1′,3′‐dioxolano)‐1‐thia‐1,1‐dioxide ( 4 ), which is the key intermediate for the synthesis of 7‐aroyl‐11‐aryl‐2,4‐diazaspiro[5,5]undecane‐1,3,5‐trione‐9‐thia‐9,9‐dioxide( 10 )/3‐thioxo‐1,5‐dione‐9‐thia‐9,9‐dioxide ( 11 ), 6‐aroyl‐10‐aryl‐2,3‐diazaspiro[4,5]decane‐1,4‐dione‐8‐thia‐8,8‐dioxide ( 12 )/2‐oxo‐3‐azaspiro [4,5]decane‐1,4‐dione‐8‐thia‐8,8‐dioxide ( 13 ). The new compounds were characterized by IR and ¹H NMR spectral data. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:131–135, 2001     

Crystal structures of N1, N5‐dibenzoyltetrahydro‐4‐methyl‐1, 5‐benzodiazepin‐2‐one (DBTBO) and tetrahydro‐4‐methyl‐1, 5‐benzodiazepin‐2‐one (TBO)

Adducing structural analogies between the two fused systems, N1, N5‐Dibenzoyltetrahydro‐4‐methyl‐1,5‐benzodiazepin‐2‐one, C₂₄H₂₀N₂O₃ (DBTBO CCDC 200341) and Tetrahydro‐4‐methyl‐1,5‐benzodiazepin‐2‐one, C₁₀H₁₂ N₂O (TBO CCDC 200342) helps to find the pharmacological differences from the view point of variant hetero atom substitutions in the hetero cycle. Both the diazepines crystallized in identical monoclinic space group P2₁/n with a = 14.1134(1) Å, b = 9.2444(1) Å, c = 16.3812(1) Å; β = 107.11(1)º, V = 2042.7(3) ų for DBTBO and a = 9.3363(7) Å, b = 10.4895(8) Å, c = 9.9852(7) Å, β = 91.314(1)º, V = 977.62(1) ų for TBO, respectively. The two structures were solved by direct methods and refined by full‐matrix least‐squares procedure to final R‐values of R1 = 0.0575(DBTBO) and R1 = 0.0984(TBO). Structural differences include non‐identical boat conformations of these seven‐membered rings and the different non‐bonding interactions in the benzodiazepine pair.     

Palladium(II) complexes of 5-substituted isatin thiosemicarbazones: Synthesis,spectroscopic characterization,biological evaluation and in silico docking studies

Substituted heterocyclic (isatin) appended thiosemicarbazone ligands (L1–L3) are synthesized by condensation of substituted isatin molecule with N(4)-phenyl-3-thiosemicarbazide in good yields. The palladium(II) complexes are synthesized from ligands (L1–L3) and PdCl₂, with a general formula [PdCl(X-C₁₅H₁₀N₄OS)] where X?=?5-chloro (1), 5-bromo (2), and 5-nitro (3). Both analytical and spectroscopic methods have been used for the analysis and characterization of the synthesized compounds. The antimicrobial activity results observed that complexes, 1 and 2 have registered potent antibacterial activity against B. subtilis and K. pneumoniae and also complex 2 has shown good antifungal activity against the micro organisms. The antioxidant activity analysis revealed that the complex 3 showed significant activity with IC₅₀ values 7.24?±?0.09?µM. Moreover, the in vitro antiproliferative activity results suggested that complex 3 exhibited high activity against HeLa cell line compared with the standard with the IC₅₀ value 16.52?±?1.08?µM. The docking results correlate well.     

NHC‐Coordinated Diphosphene‐Stabilized Gold(I) Hydride and Its Reversible Conversion to Gold(I) Formate with CO2

An NHC‐coordinated diphosphene is employed as ligand for the synthesis of a hydrocarbon‐soluble monomeric Au^I hydride, which readily adds CO₂ at room temperature yielding the corresponding Au^I formate. The reversible reaction can be expedited by the addition of NHC, which induces β‐hydride shift and the removal of CO₂ from equilibrium through the formation of an NHC‐CO₂ adduct. The Au^I formate is alternatively formed by dehydrogenative coupling of the Au^I hydride with formic acid (HCO₂H), thus in total establishing a reaction sequence for the Au^I hydride mediated dehydrogenation of HCO₂H as chemical hydrogen storage material.     

Synthesis,spectral characterization,docking studies and biological activity of urea,thiourea, sulfonamide and carbamate derivatives of imatinib intermediate

Molecular Diversity - A series of new urea/thiourea derivatives 3a–j were synthesized by simple addition reaction of functionalized phenyl isocyanates/isothiocyanates 2a–j with...     

Fully sp2-Carbon-Linked Crystalline Two-Dimensional Conjugated Polymers: Insight into 2D Poly(phenylenecyanovinylene) Formation and its Optoelectronic Properties

Cyano-substituted polyphenylene vinylenes (PPVs) have been the focus of research for several decades owing to their interesting optoelectronic properties and potential applications in organic electronics. With the advent of organic two-dimensional (2D) crystals, the question arose as to how the chemical and optoelectronic advantages of PPVs evolve in 2D compared with their linear counterparts. In this work, we present the efficient synthesis of two novel 2D fully sp²-carbon-linked crystalline PPVs and investigate the essentiality of inorganic bases for their catalytic formation. Notably, among all bases screened, cesium carbonate (Cs₂CO₃) plays a crucial role and enables reversibility in the first step with subsequent structure locking by formation of a C=C double bond to maintain crystallinity, which is supported by density functional theory (DFT) calculations. A quantifiable energy diagram of a “quasi-reversible reaction” is proposed, which allows the identification of further suitable C−C bond formation reactions for 2D polymerizations. Moreover, the narrowing of the HOMO–LUMO gap is delineated by expanding the conjugation into two dimensions. To enable environmentally benign processing, the post-modification of 2D PPVs is further performed, which renders stable dispersions in the aqueous phase.     

Activation of Aromatic C−F Bonds by a N-Heterocyclic Olefin (NHO)

A N-heterocyclic olefin (NHO), a terminal alkene selectively activates aromatic C−F bonds without the need of any additional catalyst. As a result, a straightforward methodology was developed for the formation of different fluoroaryl-substituted alkenes in which the central carbon–carbon double bond is in a twisted geometry.