Multicolor, large-area fluorescence sensing through oligothiophene-self-assembled monolayers

We present a new strategy to realize self-assembled monolayers (SAMs) on quartz and silicon with a multicolour fluorescence pattern starting from a single, proton sensitive oligothiophene dye exposed at a defined pH. Fine tuning of the SAMs emission color over the entire visible range, including white, is demonstrated. Finally, integration of SAMs in patterned thin layer cells (TLCs) is exploited to demonstrate cation sensing potential in real devices.     

Polymer control of ligand display on gold nanoparticles for multimodal switchable cell targeting

The function of cell-specific ligands on gold nanoparticles can be selectively gated by the action of co-grafted thermosensitive polymers. Below the LCST the responsive chain-extended polymers prevent cell-surface receptors from accessing the affinity ligands while above the LCST, the polymers collapse exposing the ligands and allowing binding to receptors, which in turn promotes cell internalisation.     

Existence of minmax points in discontinuous strategic games

In this note we prove the existence of minmax points for strategic form games where the sets of strategies are topological spaces and the payoff functions satisfy conditions weaker than continuity. The employed tools are the class of transfer weakly upper continuous functions and the class of weakly lower pseudocontinuous functions. An example shows that our result is of minimal character.     

Dirichlet‐to‐Neumann Map for a Nonlinear Diffusion Equation

A nonlinear diffusive equation with moving boundaries is analyzed by constructing the corresponding Dirichlet‐to‐Neumann map. In particular, the Dirichlet boundary value and the initial condition are used to derive the unknown Neumann boundary value. Then, a contraction‐mapping technique is used to prove existence and uniqueness of the solution for small times.     

Application of charged single isomer derivatives of cyclodextrins in capillary electrophoresis for chiral analysis

The review focuses on the role of ionic or ionisable single isomer derivatives (SIDs) of cyclodextrins on the separation of chiral analytes in capillary electrophoresis (CE), covering the period since the year 2000. The advantages of using pure compounds are discussed, as well as the ways to optimise the separations in the context of a rational approach to these techniques. Specific attention is paid to the modulation of the selector–analyte interaction. The advantage due to a detailed knowledge of equilibria occurring in solution during the CE run is underlined, particularly in the case of the presence of metal complexes, as occurs in chiral ligand exchange capillary electrophoresis (CLECE).     

Local current mapping and patterning of reduced graphene oxide

Conductive atomic force microscopy (C-AFM) has been used to correlate the detailed structural and electrical characteristics of graphene derived from graphene oxide. Uniform large currents were measured over areas exceeding tens of micrometers in few-layer films, supporting the use of graphene as a transparent electrode material. Moreover, defects such as electrical discontinuities were easily detected. Multilayer films were found to have a higher conductivity per layer than single layers. It is also shown that a local AFM-tip-induced electrochemical reduction process can be used to pattern conductive pathways on otherwise-insulating graphene oxide. Transistors with micrometer-scale tip-reduced graphene channels that featured ambipolar transport and an 8 order of magnitude increase in current density upon reduction were successfully fabricated.     

A Light‐Harvesting Antenna Resulting from the Self‐Assembly of Five Luminescent Components: A Dendrimer,Two Clips,and Two Lanthanide Ions

We have investigated the self‐assembly of three luminescent species in CH₃CN/CH₂Cl₂, namely: 1) a polylysin dendrimer ( D ) composed of 21 aliphatic amide units and 24 green luminescent dansyl chromophores at the periphery, 2) a molecular clip ( C ) with two blue luminescent anthracene sidewalls and a benzene bridging unit that bears two sulfate groups in the para position, and 3) a near infrared (NIR)‐emitting Nd³⁺ ion. For purposes of comparison, analogous systems have also been investigated in which Gd³⁺ replaced Nd³⁺. The dendrimer and the clip can bind Nd³⁺ ions with formation of [ D? 2 Nd³⁺] and [ C? Nd³⁺] complexes, in which energy transfer from dansyl and, respectively, anthracene to Nd³⁺ ion takes place with 65 and 8 % efficiency, in air‐equilibrated solution. In the case of [ C? Nd³⁺], the energy‐transfer efficiency is quenched by dioxygen, thereby showing that the energy donor is the lowest triplet excited state of anthracene. In [ D? 2 Nd³⁺] the intrinsic emission efficiency of Nd³⁺ is much higher (ca. 5 times) than in [ C? Nd³⁺] because of a better protection of the excited lanthanide ion towards nonradiative deactivation caused by interaction with solvent molecules. By mixing solutions of D , Nd³⁺, and C with proper concentrations, a supramolecular structure with five components of three different species, [ D? 2 Nd³⁺ ? 2 C ], is formed. The excitation light absorbed by the clips is transferred with 100 % efficiency to the dansyl units of the dendrimer and then to the Nd³⁺ ions with 65 % efficiency either in the presence or absence of dioxygen. These results show that the [ D? 2 Nd³⁺ ? 2 C ] complex is able to efficiently harvest UV light by the 24 dansyl units of the dendrimer and the four anthracene chromophores of the two clips, and efficiently transfer it to the encapsulated Nd³⁺ ions that emit in the NIR spectral region.     

Unlocking Access to Enantiopure Fused Uracils by Chemodivergent [4+2] Cross-Cycloadditions: DFT-Supported Homo-Synergistic Organocatalytic Approach

The discovery of chemical methods enabling the construction of carbocycle-fused uracils which embody a three-dimensional and functional-group-rich architecture is a useful tool in medicinal chemistry oriented synthesis. In this work, an unprecedented amine-catalyzed [4+2] cross-cycloaddition is documented; it involves remotely enolizable 6-methyluracil-5-carbaldehydes and β-aryl enals, and chemoselectively produces two novel bicyclic and tricyclic fused uracil chemotypes in good yields with a maximum level of enantiocontrol. In-depth mechanistic investigations and control experiments support an intriguing homo-synergistic organocatalytic approach, where the same amine organocatalyst concomitantly engages both aldehyde partners in a stepwise eliminative [4+2] cycloaddition, whose vinylogous iminium ion intermediate product may diverge—depending upon conditions—to either bicyclic targets by hydrolysis or tricyclic products by a second homo-synergistic trienamine-mediated stepwise [4+2] cycloaddition.     

Structural control design and defective systems

The intersection between the two concepts of structural control and defectiveness is discussed. Two simple oscillators differently connected by serial spring-dashpot arrangement are used to simply simulate technically relevant cases: dissipatively coupled adjacent free-standing structures, structures equipped by TMD and base-isolated structures. Eigensolution loci of the two classes of systems are tracked against one or more significant parameters to determine the potential benefits realized by different combinations of stiffness and viscosity. In both studied cases, codimension-two manifolds in the four-parameter space corresponding to coalescing eigenvalues are determined by analytical expressions. Conditions to discern semi-simple eigenvalues from defective ones confirm that the latter is the generic case laying in a two-parameter space while the former span a one-parameter subspace. The knowledge of the location of the defective systems in the parameter space permits to determine regions with specific dynamical properties useful for control design purpose.