1,3‐Bis[2‐(2‐hydroxybenzylideneamino)phenoxy]propane

The title compound {systematic name: 2,2′‐[1,3‐propanediyldioxydi‐o‐phenylenebis(nitrilomethylidyne)]diphenol}, C₂₉H₂₆N₂O₄, exists as the phenol–imine form in the crystal, and there are strong intramolecular O—H⋯N hydrogen bonds, with O⋯N distances of 2.545 (2) and 2.579 (2) Å. The C=N imine bond distances are in the range 1.276 (2)–1.279 (2) Å and the C=N—C bond angles are in the range 123.05 (16)–124.64 (17)°. The configurations about the C=N bonds are anti (1E).     

A modular "toolbox" approach to flexible branched multimacrocyclic hosts as precursors for multiply interlocked architectures

Tetralactam macrocycles can be functionalized by a variety of cross-coupling reactions. A modular "toolbox" strategy is presented that allows 1) several tetralactam macrocycles to be covalently connected with each other or with a central spacer, 2) the macrocycles to be substituted with or connected to different chromophores, and 3) metal-coordination sites to be attached to the macrocycles. With this approach a series of different oligo-macrocyclic hosts was obtained with great structural diversity and enormous potential for further functionalization. Rotaxanes made on the basis of these macrocycles have been synthesized to demonstrate their utility in building more complex supramolecular architectures.     

The Synthesis and Acid-Catalyzed Hydrolysis of N-(4-Substitutedphenyl)-O-Benzenedisulfonimides

Abstract

The acid catalyzed hydrolyses of some cyclic disulfonimides, N-(4-substitutedphenyl)-o-benzenedisulfonimides (1a–d) have been studied in concentrated aqueous acidic solutions. Analysis of the data by the Excess Acidity Method, activation parameters, substituent, and solvent deuterium isotope effect are all indicate hydrolysis by an A-1 mechanism in the studied range.     

Synthesis and spectroscopy of an oligophenyl based cruciform with remarkable pi-pi assisted folding

A facile route has been developed for the preparation of a new family of oligophenyls based on a 2,5,2',5'-tetra-aryl substituted biphenyl structural motif. The cruciform terphenyl dimer 2,5,2',5'-tetra(4-tert-butylphenyl)-1,1'-biphenyl () has been prepared in a two step protocol as a representative of this interesting class of materials. The thermal behaviour of the cruciform was analysed by DSC and shows that forms an amorphous glass when cooled from the isotropic melt. Subsequent heating reveals a glass transition temperature at 130 degrees C. X-Ray single crystal structure analysis of 2,2'-bis(4-tert-butylphenyl)-1,1'-biphenyl () and shows that both these molecules with a quater-phenyl substructure adopt a folded solid-state structure. Examining the (1)H NMR spectra of and reveals that the interactions that induce this folding in the solid-state are sufficiently strong to bias foldamer formation also in solution. Consequently, it is reasonable to assume that the folded conformation within the lattice is due to intramolecular pi-pi interaction rather than being imposed by crystal packing. The optical properties of the cruciform terphenyl dimer are discussed relative to the linear analogue 1,4-bis(4-tert-butylterphenyl)benzene ().     

Polyprenyl-hydroquinones and -furans from three marine sponges inhibit the cell cycle regulating phosphatase CDC25A

The CDC25 phosphatases regulate the cell division cycle by controlling the activity of cyclin-dependent kinases. While screening for inhibitors of phosphatases among natural products we repeatedly found that some polyprenyl-hydroquinones and polyprenyl-furans (furanoterpenoids) (furospongins, furospinosulins) were potent CDC25 phosphatase inhibitors. These compounds were extracted, isolated and identified independently from three sponge species (Spongia officinalis, Ircinia spinulosa, Ircinia muscarum), collected at different locations in the Mediterranean Sea. The compounds were inactive on the Ser/Thr phosphatase PP2C-alpha and on three kinases (CDK1, CDK5, GSK-3), suggesting that some potent and selective CDC25 phosphatase might be designed from these initial structures.     

Multi-mode resource constrained multi-project scheduling and resource portfolio problem

This paper introduces a multi-project problem environment which involves multiple projects with assigned due dates; activities that have alternative resource usage modes; a resource dedication policy that does not allow sharing of resources among projects throughout the planning horizon; and a total budget. Three issues arise when investigating this multi-project environment. First, the total budget should be distributed among different resource types to determine the general resource capacities, which correspond to the total amount for each renewable resource to be dedicated to the projects. With the general resource capacities at hand, the next issue is to determine the amounts of resources to be dedicated to the individual projects. The dedication of resources reduces the scheduling of the projects’ activities to a multi-mode resource constrained project scheduling problem (MRCPSP) for each individual project. Finally, the last issue is the efficient solution of the resulting MRCPSPs. In this paper, this multi-project environment is modeled in an integrated fashion and designated as the resource portfolio problem. A two-phase and a monolithic genetic algorithm are proposed as two solution approaches, each of which employs a new improvement move designated as the combinatorial auction for resource portfolio and the combinatorial auction for resource dedication. A computational study using test problems demonstrated the effectiveness of the solution approach proposed.     

A tabu search algorithm for the single machine total weighted tardiness problem

In this study, a tabu search (TS) approach to the single machine total weighted tardiness problem (SMTWT) is presented. The problem consists of a set of independent jobs with distinct processing times, weights and due dates to be scheduled on a single machine to minimize total weighted tardiness. The theoretical foundation of single machine scheduling with due date related objectives reveal that the problem is NP-hard, rendering it a challenging area for meta-heuristic approaches. This paper presents a totally deterministic TS algorithm with a hybrid neighborhood and dynamic tenure structure, and investigates the strength of several candidate list strategies based on problem specific characteristics in increasing the efficiency of the search. The proposed TS approach yields very high quality results for a set of benchmark problems obtained from the literature.