Synthesis and liquid membrane transport properties of photolabile molecular clips based on dithiane-spiro-crown ethers

[reaction: see text]. Synthesis of novel dithiane-spiro-crown ethers starting from 5,5-di(hydroxymethyl)-1,3-dithiane is developed. These compounds can be used as building blocks to assemble photolabile bis-crown ethers via addition to dicarbonyl-containing tethers, e.g., isophthalic aldehyde. It is found that unlike their mono-crown precursors such bidentate bis-crowns are capable of efficient liquid membrane transport of, for example, methyl viologen. The transport can be interrupted photochemically, providing a basis for developing smart light-responsive membranes.     

Molecular assembly and disassembly: novel photolabile molecular hosts

A new approach to the assembly and photochemical disassembly of molecular hosts is developed. It is based on photoinduced fragmentation in hydroxyalkyl dithianes and utilizes a novel spiro-bis-dithiane as a photolabile molecular tether to link two formylated macromolecular blocks, e.g., formyl calixarenes or formyl dibenzocrown ethers. A key feature of this molecular system is that after an assembly-disassembly cycle the starting macromolecular blocks are recovered intact and can be used again.     

Direct transformation of 1,3-dihalides into dithianes and dithiepines via a novel one-pot reaction with carbon disulfide and sodium borohydride

[formula: see text] 1,3-Dithianes and -dithiepines are prepared via an experimentally simple and efficient direct transformation of 1,n-alkyl dihalides utilizing carbon disulfide and sodium borohydride.     

Boolean trends in linear inequalities

This is a short overview of some recent tendencies in the theory of linear inequalities that are evoked by Boolean valued analysis.     

Structural Reassignment of Two Polyenol Natural Products

Unusual polyenols that defied chemical principles were reassigned as the nucleosides, adenosine and uridine, using a combination of chemical intuition underpinned by Computer Assisted Structure Elucidation (CASE) and DFT methods.     

Liposomes from novel photolabile phospholipids: light-induced unloading of small molecules as monitored by PFG NMR

A molecular dithiane-based approach to synthesis of novel photolabile phospholipids is developed. These lipids are used in formulations with egg-POPC and cholesterol to prepare light-sensitive liposomes. Irradiation of such liposomes in PBS buffer (medium pressure mercury lamp, Pyrex filter, lambda > 300 nm) significantly increases the bilayer permeability and accelerates the release of entrapped small organic molecules by an order of magnitude. A simple assay, based on (1)H or (19)F PFG NMR measurements of diffusion coefficients, is developed to monitor light-induced unloading of the probe molecules.     

On order bounded disjointness preserving operators

The paper is aimed at demonstrating that some properties of order bounded operators in vector lattices are just Boolean valued interpretations of elementary properties of order bounded functionals. We present the general machinery and illustrate it with a few new results on order bounded disjointness preserving and n-disjoint operators.     

Conformational analysis of spiro-bis-dithiepins: a peculiar case of axial chirality

Spiro-bis-dithiepins are synthesized via dehydrative ring expansion in alpha-hydroxyalkyl spiro-bis-dithianes. Atypical of spiranes possessing axial chirality, the two most stable conformers of substituted spiro-bis-dithiepin have virtually colinear double bonds; i.e., each enantiomer exists in a form of two energy degenerate syn and anti conformations. Because of the high polarizability of the vinyl sulfide moiety, spiro-bis-dithiepins bearing electron-withdrawing substituents offer access to two-state systems possessing large dipole moments, which can be modulated by conformational events. [structure: see text]