Well-defined novel fluorene-containing polymers: synthesis, fluorescent properties, and micellar nanoparticles

Air-Stable Pd Catalytic Systems for Sequential One-Pot Synthesis of Challenging Unsymmetrical Aminoaromatics

The selective functionalization of dibromoaromatic scaffolds using air-stable palladium catalytic systems was carried out. This methodology involved rapid mono and diselective Buchwald-Hartwig aminations via microwave irradiation. The conditions were optimized to couple sequentially different moieties in one pot. Couplings with a wide scope of amines allowed accessing a new library of symmetrical and unsymmetrical derivatives (35 examples). Using this versatile method, a near-IR push-pull sensor was prepared installing the electron-donating and -withdrawing groups through a multicomponent reaction. These conditions revealed to be gram-scalable and adaptable to various groups; hence, promoting facile use in synthetic chemistry.

Fluorescent Block Copolymer Micelles That Can Self-Report on Their Assembly and Small Molecule Encapsulation

Block copolymer micelles have been prepared with a dithiomaleimide (DTM) fluorophore located in either the core or shell. Poly(triethylene glycol acrylate)-b-poly(tert-butyl acrylate) (P(TEGA)-b-P(tBA)) was synthesized by RAFT polymerization, with a DTM-functional acrylate monomer copolymerized into either the core forming P(tBA) block or the shell forming P(TEGA) block. Self-assembly by direct dissolution afforded spherical micelles with R_h of ca. 35 nm. Core-labeled micelles (CLMs) displayed bright emission (Φ_f = 17%) due to good protection of the fluorophore, whereas shell-labeled micelles (SLMs) had lower efficiency emission due to collisional quenching in the solvated corona. The transition from micelles to polymer unimers upon dilution could be detected by measuring the emission intensity of the solutions. For the core-labeled micelles, the fluorescence lifetime was also responsive to the supramolecular state, the lifetime being significantly longer for the micelles (τ_Av,I = 19 ns) than for the polymer unimers (τ_Av,I = 9 ns). The core-labeled micelles could also self-report on the presence of a fluorescent hydrophobic guest molecule (Nile Red) as a result of Förster resonance energy transfer (FRET) between the DTM fluorophore and the guest. The sensitivity of the DTM fluorophore to its environment therefore provides a simple handle to obtain detailed structural information for the labeled polymer micelles. A case will also be made for the application superiority of core-labeled micelles over shell-labeled micelles for the DTM fluorophore.

Palladium local structure of La1−xSrxCo1−yFey−0.03Pd0.03O3−δ perovskites synthesized using a one pot citrate method

Pd local environment in the LSCF perovskite phase.