The Synthesis of 4,11,18,25-Tetrachloro [14]metacyclophane-7,14,21,28-tetroi,Structural Analogues of Phloroglucides

The synthesis of the title compounds is described. Some of the compounds prepared exhibited antimicrobial activity in vitro. Structure-activity relationship is briefly discussed.     

β-Diketiminate complexes of Group 4: active complexes for the isomerization of α-olefins and the polymerization of propylene towards elastomeric polypropylene

The β-diketiminate lithium ligand [{N(SiMe₃)C(Ph)}₂CH][Li] reacted with Group 4 metal salts (Ti and Zr) to yield the complexes [{N(SiMe₃)C(Ph)}₂CH]₂TiCl₂ (5) and [{N(SiMe₃)C(Ph)}₂CH][N(SiMe₃)C(Ph)NC(Ph)CH(SiMe₃)]ZrCl₂ (6). The crystal structure of 6 shows that one of the two ketamidinate ligands undergoes an isomerization to the corresponding substituted benzamidinate. A mechanism for the catalyzed isomerization of the β-diketiminate ligand is presented. Complex 5 was found to be active in the polymerization of propylene, producing remarkably high-molecular weight (>100,000 g mol⁻¹) elastomeric polymer, whereas the zirconium complex was found inactive. Complex 5, and surprisingly complex 6, were found to be active catalysts, in the presence of MAO (methylalumoxane), for the isomerization of aliphatic olefins (1-octene, allylbenzene). Each complex catalyzed the olefins by different mechanisms. Kinetic studies for the isomerization of allylbenzene by complex 5 show that the reaction rate follows a first order in both catalyst and olefin concentrations with ΔH^‡=14.7(4) kcal mol⁻¹ and ΔS^‡=−33(1) e.u. These findings support the epimerization mechanism of the last inserted monomer that is proposed for as the primary cause for the elastomeric properties of polypropylene produced by this complex. In addition, we show how complementary isomerization studies of α-olefins shed light on the polymerization mechanism.     

A simple route to tetrahydro-1,4-benzodiazepin-3-ones bearing diverse N1, N4, and C10 functionalization

We describe an efficient synthesis of enantiopure tetrahydro-1,4-benzodiazepine-3-ones derived from l-alanine. Diverse substitution at N1, N4, and C10 can be achieved by coupling various N-alkyl derivatives of l-alanine and N-allyl-(2-fluoro-5-nitro)benzylamine. Cyclization of this intermediate proceeds in high yield and without racemization, providing diversity at N1. The NO₂ group was easily transformed into other functional groups or removed, providing diversity at C10. Finally, oxidative deallylation allows diverse substitution to be installed at N4.     

Single-site catalysis by bimetallic zinc calixarene inclusion complexes

[reaction: see text] Bimetallic alkylzinc calixarene inclusion complexes were prepared and used in the ring-opening polymerization of L-lactide. Polymers with high molecular weight and a low degree of polydispersity were obtained. 1H NMR and diffusion NMR experiments suggest that a single-site mechanism is operative.     

A Novel and Effective Strategy for the Construction of "Tube-Like" Double Resorcin[4]arenes

The synthesis of rigid tube-shape structures from resorcin[4]arene unitscombined in the ``head-to-tail'' manner is described.Tetrabromomethylenecalix-[4]resorcinarene with all OH-groups connected viamethylene bridges was used as a starting material. Reaction withp-hydroxybenzaldehyde led to the tetraaldehyde derivative and the following condensation with resorcinol resulted in formation of a third aromatic rim. An electrochemical study comparing properties of both resorcin[4]arene and itstube-shaped analogs was performed.     

Cyclohexene Hydroconversion Using Monometallic and Bimetallic Catalysts Supported on γ‐Alumina

The hydroconversion of cyclohexene (CHE) using monometallic catalysts containing 0.35wt% of Pt, Pd, Ir or Re on a γ‐alumina support, as well as bimetallic catalysts containing combinations of 0.35wt% Pt with 0.35wt% of either Pd, Ir or Re on γ‐alumina, were investigated in a plug flow‐type fixed‐bed reactor. The Cyclohexene (CHE) feed was injected continuously with a rate of 8.33 × 10^?3mole h^?1 on 0.2 g of catalyst using a simultaneous hydrogen gas flow of 20 cm³ min^?1 throughout a broad reaction temperature range of 50–400 °C. The dispersion of the metals in the catalysts was determined via H₂ or CO chemisorption. The activities of the monometallic catalysts were found to be in the order: Pd > Pt > Ir > Re, whereas those of the bimetallic catalysts were in the order: PtPd > PtIr > PtRe. Cyclohexene hydrogenation and dehydrogenation reactions using the current mono‐ and bimetallic catalysts were kinetically investigated applying the absolute reaction rate theory, whereby reaction rate constant, activation energy, enthalpy and entropy of activation were computed to explain surface variations on these catalysts.     

Exploring New Vista of Secured and Optimized Data Slicing for Big Data: An IOT Paradigm

Security and privacy are useful concerns in the context of big data. The Internet of Things (IoT) serves both to bolster and to ease security worries. IoT gadgets raise immense new security challenges, particularly with regards to things like basic framework. Be that as it may, they additionally offer approaches to help keep clients progressively secure by adding additional obstructions of safeguard to information and people. In order to sustain the integrity of data and to provide in order to implicit security for any big database, data slicing is constructive. Data slicing implicitly provides the preservation and the query performance to the database users. The sliced data are stored at servers in a distributed system to protect the data from the attackers. In this article, an intelligent and efficient model is developed to partition the polynomial data securely and to store at various servers in a distributed system. An auto-key generator spawns an encryption key to encrypt the polynomial data as a higher level security. Encrypted data is partitioned by an efficient Fast Fourier transform Technique. A novel clustering methodology entitled as Binary Reverse Clustering is introduced to optimize the performance as well as to reduce the servers’ requisition. Moreover, the novel clustering technique is compared with the traditional clustering algorithm.