1-Azaspiro[3.3]heptane as a Bioisostere of Piperidine**

1-Azaspiro[3.3]heptanes were synthesized, characterized, and validated biologically as bioisosteres of piperidine. The key synthesis step was thermal [2+2] cycloaddition between endocyclic alkenes and the Graf isocyanate, ClO₂S−NCO, to give spirocyclic β-lactams. Reduction of the β-lactam ring with alane produced 1-azaspiro[3.3]heptanes. Incorporation of this core into the anesthetic drug bupivacaine instead of the piperidine fragment resulted in a new patent-free analogue with high activity.     

Scanning electrochemical microscopy study of ion transfer process across water/2-nitrophenyloctylether interface supported by hydrophobic carbon ceramic electrode

A carbon ceramic electrode (CCE) modified with the redox probe—decamethylferrocene solution in hydrophobic organic solvent—2-nitrophenyloctyl ether and immersed into an aqueous solution was studied by scanning electrochemical microscopy (SECM). After the electrochemical oxidation of decamethylferrocene, its cations were detected near the electrode surface in the aqueous phase. This indicates that some fraction of the redox-active cations electrochemically produced in the organic phase is transferred across the liquid/liquid interface. They are reduced at the SECM tip and form a solid deposit. The amount of deposited decamethylferrocene was estimated by the anodic reaction at the tip. It is affected by the substrate–tip distance, deposition time, and electrolyte concentration. The SECM images of unmodified and modified CCEs are consistent with their heterogeneous structure.     

Fluorinated bismuth alkoxides: from monomers to polymers and oxo-clusters

A series of new bismuth fluoroalkoxide compounds have been prepared through the treatment of 1,1,1,3,3,3-hexafluoro-2-propanol with BiAr3 (where Ar=Ph, p-Tol). Reactions were conducted without the use of any additional solvent and the reaction products distilled or extracted with non-polar or polar Lewis base solvents. Structural analyses reveal that under variable reaction conditions the interaction of BiAr3 with (CF3)2CHOH can give a mixture of bismuth complexes with varying degrees of substitution, cluster formation and aggregation. Compounds [Bi(OCH(CF3)2)3(pyr)2] () (pyr=pyridine), [Bi(OCH(CF3)2)3(thf)3] () (thf=tetrahydrofuran), [Bi2(OCH(CF3)2)3(dabco)3] () (dabco=1,4-diazabicyclo[2.2.2]octane), [PhBi(OCH(CF3)2)2]n (), [Bi2O(OCH(CF3)2)4(C7H8)]2 () (C7H8=toluene), [Bi9O7(OCH(CF3)2)13] (), [Bi2O(OCH(CF3)2)4(Et2O)]2 (), [Bi2O(OCH(CF3)2)4(thf)]2 () and [Bi2O(OCH(CF3)2)4(tmeda)2] () (tmeda=N,N,N',N'-tetramethylethylenediamine) have been fully characterised including by single crystal X-ray diffraction.     

On-Demand Cell Sheet Release with Low Density Peptide-Functionalized Non-LCST Polymer Brushes

Cell sheet harvesting offers a great potential for the development of new therapies for regenerative medicine. For cells to adhere onto surfaces, proliferate, and to be released on demand, thermoresponsive polymeric coatings are generally considered to be required. Herein, an alternative approach for the cell sheet harvesting and rapid release on demand is reported, circumventing the use of thermoresponsive materials. This approach is based on the end-group biofunctionalization of non-thermoresponsive and antifouling poly(2-hydroxyethyl methacrylate) (p(HEMA)) brushes with cell-adhesive peptide motifs. While the nonfunctionalized p(HEMA) surfaces are cell-repellant, ligation of cell-signaling ligand enables extensive attachment and proliferation of NIH 3T3 fibroblasts until the formation of a confluent cell layer. Remarkably, the formed cell sheets can be released from the surfaces by gentle rinsing with cell-culture medium. The release of the cells is found to be facilitated by low surface density of cell-adhesive peptides, as confirmed by X-ray photoelectron spectroscopy. Additionally, the developed system affords possibility for repeated cell seeding, proliferation, and release on previously used substrates without any additional pretreatment steps. This new approach represents an alternative to thermally triggered cell-sheet harvesting platforms, offering possibility of capture and proliferation of various rare cell lines via appropriate selection of the cell-adhesive ligand.     

Determination of SLES in Personal Care Products by Colloid Titration with Light Reflection Measurements

The method of colloid titration with poly(diallyldimethylammonium) chloride has been improved to detect the endpoint with an off-vessel light reflectance sensor. The digital color sensor used measures light reflectance by means of light guides, with no immersion into the reaction solution. In such a method, the optical signal is free of disturbances caused by sticky flocs in the solution. The improved automatic titration set was applied for the determination of sodium laureth sulfate (SLES) in industrial batches and commercial personal care products. The sample color and opacity do not disturb the SLES quantification. When the SLES content lies in the range from 5% to 9%, the optimal sample weight is from 6 g to 3 g.     

Nanopatterning of substrates by self-assembly in supramolecular block copolymer monolayer films

Many technological applications require templates with nanoscale patterns.Block copolymer self-assembly is a method of choice for obtaining a large variety of such patterns,with greatest flexibility achieved when combined with a supramolecular approach.One of the ways to fabricate block copolymer templates is the Langmuir-Blodgett (LB) technique.Here,we briefly summarize recent work with LB films of polystyrene-poly(4-vinyl pyridine) (PS-P4VP) mixed with 3-n-pentade cylphenol (PDP),illustrating the different types of patterns possible and the principles governing them.One interesting pattern that can be easily achieved with this system is the so-called "nanostrand network",which,when used as a template for gold deposition,can produce double striped lines of gold.Here,we show how this pattern can be modified by acetone swelling to give rise to gold monolayer ribbons with internal structure.The results also suggest new insights into the early stages of morphology formation at the air/water interface.     

Ligand Effect in Alkali-Metal-Catalyzed Transfer Hydrogenation of Ketones

This work unveils the reactivity patterns, as well as ligand and additive effect on alkali-metal-base-catalyzed transfer hydrogenation of ketones. Crucially to this reactivity is the presence of a Lewis acid (alkali cation), as opposed to a simple base effect. With aryl ketones, the observed reactivity order is Na⁺>Li⁺>K⁺, whereas for aliphatic substrates it follows the expected Lewis acidity, Li⁺>Na⁺>K⁺. Importantly, the reactivity pattern can be drastically changed by adding ligands and additives. Kinetic, labelling, and competition experiments as well as DFT calculations suggested that the reaction proceeds through a concerted direct hydride-transfer mechanism, originally suggested by Woodward. The lithium cation was found to be intrinsically more active than heavier congeners, but in the case of aryl ketones a decrease in reaction rate was observed at ≈40 % conversion with lithium cations. Noncovalent-interaction analysis revealed that this deceleration effect originated from specific noncovalent interactions between the aryl moiety of 1-phenylethanol and the carbonyl group of acetophenone, which stabilize the product in the coordination sphere of lithium and thus poison the catalyst. The ligand/additive effect is a complicated phenomenon that includes a combination of several factors, such as the decrease of activation energy by ligation (confirmed by distortion/interaction calculations of N,N,N’,N’-tetramethylethylenediamine, TMEDA) and the change in relative stabilization of reagents and substrates in the solution and the coordination sphere of the metal. Finally, we observed that lithium-base-catalyzed transfer hydrogenation can be further facilitated by the addition of an inexpensive and benign reagent, LiCl, which likely operates by re-initiating the reaction on a new lithium center.