Conventional vs. Microwave- or Mechanically-Assisted Synthesis of Dihomooxacalix[4]arene Phthalimides: NMR,X-ray and Photophysical Analysis §

Direct O-alkylation of p-tert-butyldihomooxacalix[4]arene (1) with N-(bromopropyl)- or N-(bromoethyl)phthalimides and K₂CO₃ in acetonitrile was conducted under conventional heating (reflux) and using microwave irradiation and ball milling methodologies. The reactions afforded mono- and mainly distal di-substituted derivatives in the cone conformation, in a total of eight compounds. They were isolated by column chromatography, and their conformations and the substitution patterns were established by NMR spectroscopy (¹H, ¹³C, COSY and NOESY experiments). The X-ray structures of four dihomooxacalix[4]arene phthalimide derivatives (2a, 3a, 3b and 5a) are reported, as well as their photophysical properties. The microwave (MW)-assisted alkylations drastically reduced the reaction times (from days to less than 45 min) and produced higher yields of both 1,3-di-substituted phthalimides (3a and 6a) with higher selectivity. Ball milling did not reveal to be a good method for this kind of reaction.     

Repdigits as sums of three Pell numbers

In this paper, all base 10 repdigits expressible as sums of three Pell numbers are found.     

Merging the Isonitrile-Tetrazine (4+1) Cycloaddition and the Ugi Four-Component Reaction into a Single Multicomponent Process

Multicomponent reactions are of utmost importance at generating a unique, wide, and complex chemical space. Herein we describe a novel multicomponent approach based on the combination of the isonitrile-tetrazine (4+1) cycloaddition and the Ugi four-component reaction to generate pyrazole amide derivatives. The scope of the reaction as well as mechanistic insights governing the 4H-pyrazol-4-imine tautomerization are provided. This multicomponent process provides access to a new chemical space of pyrazole amide derivatives and offers a tool for peptide modification and stapling.     

Study of multi-nucleon transfer reactions in 58, 64Ni + 207Pb collisions at the velocity filter SHIP

The European Physical Journal A - We investigated multi-nucleon transfer reactions in collisions of 58Ni + 207Pb and 64Ni + 207Pb at Coulomb barrier energies. The new aspect is that we used a...     

Finding all pure strategy Nash equilibria in a planar location game

In this paper, we deal with a planar location-price game where firms first select their locations and then set delivered prices in order to maximize their profits. If firms set the equilibrium prices in the second stage, the game is reduced to a location game for which pure strategy Nash equilibria are studied assuming that the marginal delivered cost is proportional to the distance between the customer and the facility from which it is served. We present characterizations of local and global Nash equilibria. Then an algorithm is shown in order to find all possible Nash equilibrium pairs of locations. The minimization of the social cost leads to a Nash equilibrium. An example shows that there may exist multiple Nash equilibria which are not minimizers of the social cost.     

Heterotelechelic Polymers for Capture and Release of Protein-Polymer Conjugates

A heterotelechelic biotin-maleimide polymer containing a cleavable disulfide bond was synthesized by RAFT polymerization and used to reversibly modify surfaces with proteins.     

Study of polymorphous silicon and germanium as thermo-sensing films for infrared detectors

In this work we present a comparative study on the electrical characteristics of polymorphous silicon (pm-Si:H) and polymorphous germanium (pm-Ge:H) thin films deposited by low frequency plasma enhanced chemical vapor deposition (LF-PECVD), aiming to use them as thermo sensing elements in un-cooled microbolometers.We studied the effect of the deposition pressure on the film characteristics that are important for IR detection, as the activation energy (E_a), the thermal coefficient of resistance (TCR), the room temperature conductivity (σ_RT) and the film responsivity with IR radiation.Our results indicate that polymorphous films have advantages over boron doped a-Si:H, material which is currently employed as thermo-sensing element in commercial microbolometer arrays.