Influence of the Metal Ion on the Two‐Photon Absorption Properties of Lanthanide Complexes Including Near‐IR Emitters

The synthesis of tris(2‐thenoyltrifluoroacetonate)lanthanide(III) complexes featuring a diethylaminostyryl‐2,2′‐bipyridine coligand was achieved for lanthanum; the near‐infrared (NIR) emitters neodymium, erbium, and ytterbium; and the transition‐metal yttrium. The photophysical properties were thoroughly studied, and it was demonstrated that the conjugated bipyridine ligand acts as a good antenna for the sensitization of the NIR emitters. The two‐photon absorption (TPA) properties of all five complexes were investigated by using both two‐photon excited fluorescence and the Z‐scan method. We demonstrate that the nature of the rare earth ion has almost no influence on the TPA properties centered on the conjugated bipyridyl ligand. Finally, we show that Yb^III is sensitized by a two‐photon antenna effect, and that Nd^III is mostly sensitized by a one‐photon process involving direct excitation of forbidden f–f transitions.     

A new DMAP-catalyzed and microwave-assisted approach for introducing heteroarylamino substituents at position-4 of the quinazoline ring

We report herein a new methodology for synthesizing quinazoline derivatives bearing a heteroarylamino moiety at position-4 of the quinazoline ring. As an alternative to the Buchwald–Hartwig cross-coupling reaction, which appears, until now, as the only efficient way to react 4-chloroquinazolines with numerous amino nitrogen-containing heterocycles displaying poor nucleophilicity, we developed a DMAP-catalyzed reaction involving microwave irradiation. Optimization of the reaction conditions led to the use of 30 mol % of DMAP in toluene, using a monomode microwave reactor and sealed vials. Moreover, the S_NAr reaction intermediate salt was isolated and fully characterized. Finally, the procedure was extended to two different 2-substituted-quinazoline series and also to various anilines, demonstrating that this approach was a general efficient way to access to such 4-substituted quinazoline scaffolds of high pharmaceutical interest.     

Biomimetic Mussel Adhesive Inspired Anchor to Design ZnO@Poly(3‐Hexylthiophene) Hybrid Core@Corona Nanoparticles

The functionalization of zinc oxide (ZnO) nanoparticles by poly(3‐hexylthiophene) (P3HT) brush is completed by the combination of a mussel inspired biomimetic anchoring group and Huisgen cyclo‐addition “click chemistry.” Herein, the direct coupling of an azide modified catechol derivative with an alkyne end‐functionalized P3HT is described. This macromolecular binding agent is used to access core@corona ZnO@P3HT with a stable and homogeneous conjugated organic corona. Preliminary photoluminescence measurement proves an efficient electron transfer from the donor P3HT to the acceptor ZnO nanoparticles upon grafting, thus demonstrating the potential of such a combination in organic electronics.

     

Programmable Polymer‐Based Supramolecular Temperature Sensor with a Memory Function

A new class of polymeric thermometers with a memory function is reported that is based on the supramolecular host–guest interactions of poly(N‐isopropylacrylamide) (PNIPAM) with side‐chain naphthalene guest moieties and the tetracationic macrocycle cyclobis(paraquat‐p‐phenylene) (CBPQT⁴⁺) as the host. This supramolecular thermometer exhibits a memory function for the thermal history of the solution, which arises from the large hysteresis of the thermoresponsive LCST phase transition (LCST=lower critical solution temperature). This hysteresis is based on the formation of a metastable soluble state that consists of the PNIPAM–CBPQT⁴⁺ host–guest complex. When heated above the transition temperature, the polymer collapses, and the host–guest interactions are disrupted, making the polymer more hydrophobic and less soluble in water. Aside from providing fundamental insights into the kinetic control of supramolecular assemblies, the developed thermometer with a memory function might find use in applications spanning the physical and biological sciences.     

NMR studies of interactions of new CB2 cannabinoid receptor ligands with cyclodextrins hosts. Correlation with micellar electrokinetic chromatography and reversed phase high performance liquid chromatography

Three selective CB₂ cannabinoid receptor ligands have recently been discovered to be promising anti-inflammatory agents but their low water solubility hinder their per os administration. The popularity of the cyclodextrins, from a pharmaceutical standpoint lies on their ability to interact with poorly water-soluble drugs and improve their solubility. Herein, three experimental approaches for calculating the stability constant of complexes between the selective CB₂ ligands and either the β-CD or the HP-β-CD, were tested: nuclear magnetic resonance, micellar electrokinetic chromatography and high performance liquid chromatography in reversed phase. In NMR studies the calculated K values were relatively high and were between 1486 and 3571 M^?1 with β-CD. With HP-β-CD they were between 1203 and 2650 M^?1. Concerning the two others techniques the K values were found lower. In MECK studies with β-CD they were between 308 and 792 M^?1 and with HP-β-CD between 124 and 764 M^?1. Finally in RP-HPLC studies with β-CD, they were between 539 and 1144 M^?1 and with HP-β-CD between 196 and 396 M^?1. These calculated constants suggest that a complexation phenomenon occurs. A model for inclusion of one of the CB₂ ligands in the β-CD was then proposed from molecular modeling studies.     

Enhancement of mass spectrometric detection of LTC4, LTD4, and LTE4 by derivatization

Several acylating reagents are synthesized and used to introduce quatemary phosphonium or ammonium or ternary sulfonium functions into a simple model of a peptido leukotriene (PLT). One of these reagents was selected for further study with LTE₄, LTD₄, and LTC₄. We demonstrate that acylation of the free amine function of PLTs to produce the 5-triphenylphosphoniumvaleryl-amide (TPPV) derivatives enhances chemical stabilities and significantly increases responses in fast-atom bombardment and continuous-flow liquid secondary ion mass spectrometry (CF-LSIMS) relative to the native PLTs. With high-performance liquid chromatography inlet to CF-LSIMS, we demonstrate the facile detection in selected ion monitoring of the TPPV derivative of 3 pg of LTD₄.     

Closed-System Solution of the 1D Atom from Collision Model

Obtaining the total wavefunction evolution of interacting quantum systems provides access to important properties, such as entanglement, shedding light on fundamental aspects, e.g., quantum energetics and thermodynamics, and guiding towards possible application in the fields of quantum computation and communication. We consider a two-level atom (qubit) coupled to the continuum of travelling modes of a field confined in a one-dimensional chiral waveguide. Originally, we treated the light-matter ensemble as a closed, isolated system. We solve its dynamics using a collision model where individual temporal modes of the field locally interact with the qubit in a sequential fashion. This approach allows us to obtain the total wavefunction of the qubit-field system, at any time, when the field starts in a coherent or a single-photon state. Our method is general and can be applied to other initial field states.     

Easy and efficient selenocyanation of imidazoheterocycles using triselenodicyanide

The regioselective selenocyanation of imidazoheterocycles using triselenodicyanide at room temperature is reported. The electrophilic aromatic substitution of a broad range of substrates is promoted by the triselenodicyanide obtained by oxidative coupling of malononitrile and selenium dioxide, under an air atmosphere. The major advantages of the presented method are an easy set-up, excellent yields, short reaction times, use of odorless and inexpensive reagents and easy purification of the final products.     

Access to original spirocyclic derivatives via inter- or intramolecular reaction mediated by manganese(III) acetate

An easily reproducible protocol allowing inter- or intramolecular spirocyclization on β-dicarbonyl structures is described. This methodology could afford a wide variety of spirocyclic pharmacophores. As examples, highly substituted spirobenzophenanthridin-6(5H)-ones and spirolactones were synthesized. These scaffolds could be used for the design of many compounds exhibiting biological activities.