Photo‐initiated thiol–ene “click” hydrogels from RAFT‐synthesized poly(N‐isopropylacrylamide)

Despite the efficiency and robustness of the widely used copper‐catalyzed 1,3‐dipolar cycloaddition reaction, the use of copper as a catalyst is often not attractive, particularly for materials intended for biological systems. The use of photo‐initiated thiol‐ene as an alternative “click” reaction to synthesize “model networks” is investigated here. Poly(N‐isopropylacrylamide) precursors were synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization and were designed to have trithiocarbonate moieties as end groups. This structure design provides opportunity for subsequent end‐group modifications in preparation for thiol‐ene “click.” Two reaction routes have been proposed and studied to yield thiol and ene moieties. The advantages and disadvantages of each reaction path were investigated to propose a simple but efficient route to prepare copper‐free “click” hydrogels. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4626–4636     

Corrigendum to “Deposition of chemically reactive and repellent sites on biosensor chips for reduced non-specific binding” [Colloids Surf. B 79 (2010) 270–275]

Treatment of poly(dimethylsiloxane) (PDMS) surfaces with SF₆ plasma results in the creation of high-surface-area nanotextured surfaces that considerably favour protein adsorption with respect to untreated ones. In order to employ such nanotextured surfaces as substrates for microarrays to be created and analysed using standard instrumentation, we fabricated thin PDMS films on top of standard low-cost microscope glass slides. The properties of both untreated and plasma-treated PDMS-coated slides towards spotting of protein solutions were evaluated in terms of spot signal intensity and homogeneity as well as of spot shape and size. It was found that the plasma-treated PDMS-coated glass slides provided highly homogeneous spots (mean intra-spot variation 7.6%) with spot signal intensity 6-times higher than that obtained using the untreated ones. In addition, comparison with commercially available polystyrene and aminosilanized-glass microarray slides showed that the proposed slides provided 3-times higher spot signal intensity and 2-times lower intra-spot signal variation. In addition, the implementation of long-aged-after-plasma-treatment nanotextured PDMS-coated glass slides provided spots whose shape and size matched those of the spotting tip. As a consequence, denser arrays of variable spot shape can be created using SF₆ plasma-treated PDMS-coated slides instead of standard microarray slides opening new potentials for bioanalytical applications.     

Novel calix[4]cryptands: “Mappemonde II” and “Mill II”

Two novel calix[4]cryptands were synthesized from 1,3‐alternate calix[4]bis‐azacrown. “Mappemonde II” consists of one 1,3‐calix[4]bis‐azacrown wrapped by a benzo‐crown ether loop. “Mill II” is composed of two 1,3‐calix[4]bis‐azacrowns linked by two benzo‐crown ether strands.     

From Packed “Sandwich” to “Russian Doll”: Assembly by Charge‐Transfer Interactions in Cucurbit[10]uril

As the host possessing the largest cavity in the cucurbit[n]uril (CB[n]) family, CB[10] has previously displayed unusual recognition and assembly properties with guests but much remains to be explored. Herein, we present the recognition properties of CB[10] toward a series of bipyridinium guests including the tetracationic cyclophane known as blue box along with electron‐rich guests and detail the influence of encapsulation on the charge‐transfer interactions between guests. For the mono‐bipyridinium guest (methylviologen, MV ²⁺), CB[10] not only forms 1:1 and 1:2 inclusion complexes, but also enhances the charge‐transfer interactions between methylviologen and dihydroxynaphthalene ( HN ) by mainly forming the 1:2:1 packed “sandwich” complex (CB[10] ? 2 MV ²⁺ ?HN ). For guest 1 with two bipyridinium units, an interesting conformational switching from linear to “U” shape is observed by adding catechol to the solution of CB[10] and the guest. For the tetracationic cyclophane‐blue box, CB[10] forms a stable 1:1 inclusion complex; the two bipyridinium units tilt inside the cavity of CB[10] according to the X‐ray crystal structure. Finally, a supramolecular “Russian doll” was built up by threading a guest through the cavities of both blue box and CB[10].     

Self-Assembly of a Three-Dimensional [Ga6(L2)6] Metal–Ligand “Cylinder”

A near trigonal antiprism with metal–metal distances in the nanometer regime is formed by the six metal ions in the crystalline, homochiral [Ga₆(L²)₆] (see structure). This metal–ligand “cylinder” is based on a threefold symmetric, β-diketone ligand, and represents a new geometry for metal–ligand clusters.     

Computational determination of effects of electric fields upon “trigger linkages” of prototypical energetic molecules

For five prototypical energetic molecules (nitrobenzene, methyl azide, methyl nitrate, nitromethane, and dimethylnitramine), we examine computationally the effects of external electric fields upon their “trigger linkage” bonds, the breaking of which is believed to play a key role in detonation initiation. The bonds are, respectively, C? NO₂, N? N₂, O? NO₂, C? NO₂, and N? NO₂. The calculations are at the B3PW91/6–31G** level. We find that fields along these bonds that reinforce the molecules' intrinsic polarities also lower their energies and increase the bonds' stretching vibration frequencies. This suggests a strengthening of the bonds. Fields in the opposite direction do the reverse. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

“ESHC (sopron) plenary lecture” exciting fields in P‐heterocyclic chemistry

In our laboratory, we have been dealing with the synthesis and utilization of P‐heterocycles for almost two decades. In this paper, our recent results are summarised. In the first part, the synthesis and properties of phospholes with sterically demanding substituent on the phosphorus atom and the fragmentation‐related properties of phosphole oxide‐related 7‐phosphanorbornenes are discussed. Then, new families of 6‐membered P‐heterocycles are introduced available by a ring enlargement method and subsequent modifications. In the next part, I show how bridged P‐heterocycles were prepared and how they were utilised in fragmentation‐related phosphorylations. Finally a novel reaction providing heterocyclic phosphoranes/ylides is discussed.     

“Click” chemistry for in situ formation of thermoresponsive P(NIPAAm‐co‐HEMA)‐based hydrogels

The strategy for in situ chemical gelation of poly(N‐isopropylacrylamide‐co‐hydroxylethyl methacrylate) [P(NIPAAm‐co‐HEMA)]‐based polymers was demonstrated. Two types of new P(NIPAAm‐co‐HEMA) derivatives with alkyne and azide pendant groups, respectively, were prepared. When the solutions of the two derivatives were mixed together, a crosslinking reaction, a type of Huisgen's 1,3‐dipolar azide‐alkyne cycloaddition, in the presence of Cu(I) catalyst occurs. The morphology, equilibrium swelling ratio, swelling kinetics, and temperature response kinetics of the in situ gelated hydrogels were studied. In comparison with the conventional PNIPAAm hydrogel, because of the spatial hindrance of polymeric chains, the resulted hydrogels had a macroporous structure as well as a fast shrinking rate. The strategy described here presents a potential alternative to the traditional synthesis techniques for the in situ formation of thermoresponsive hydrogels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5263–5277, 2008