Facile Synthesis of Optically Active and Magnetic Nanoparticles Carrying Helical Poly(phenyl isocyanide) Arms and Their Application in Enantioselective Crystallization

Abstract

In this paper, the facile synthesis of hybrid Fe O magnetic nanoparticles carrying helical poly(phenyl isocyanide) (PPI) arms via both "grafting from" and "grafting onto" strategies is reported. First, alkyne-Pd(II) catalysts are anchored onto the surface of the Fe O magnetic nanoparticle, which promote the polymerization of enantiopure phenyl isocyanide, affording the expected hybrid magnetic nanoparticle with Fe O in core and helical PPI as arms. The nanoparticle also exhibits highly optical activity due to the excess of one-handed helicity of the PPI arms. Moreover, the hybrid magnetic nanoparticle can be alternatively synthesized via "grafting onto" strategy. A triethoxysilanyl-terminated single handed helical PPI bearing l-alanine ester pendants is prepared and grafted onto the surface of Fe O nanoparticle. The generated hybrid magnetic nanoparticles show both magnetic character and optical activity. Taking advantage of these properties, they can be used in enantioselective crystallization of racemic threonine. The enantiomeric excess (ee) of the induced crystals is up to 93%. Moreover, the nanoparticles can be facilely recovered and recycle used for at least four times in enantioselective crystallization without significantly loss of its enantioselectivity.

Chiral resolution of DL‐glutamic acid by a chiral additive

“…An equimolar mixture of D and L molecules dissolved in water typically produces a racemic solution. Crystallization is a useful separation method to resolve the constituents of a racemate, [5][6][7] and there is no doubt that the crystals yielded from this solution should belong to one of the following types: D crystals, L crystals, racemic compound crystals (DL crystals, crystals containing both D and L enantiomers) or conglomerates (mixtures of D crystals and L crystals). For most amino acids, the crystals deposited from a racemic solution are racemic, and it is impossible to resolve the D and L molecules from DL crystals because the two enantiomers are distributed homogeneously throughout the crystal lattice.…”

Catechol as a Universal Linker for the Synthesis of Hybrid Polyfluorene/Nanoparticle Materials

“…17−22 However, each application requires a specific CP/NP combination, which in turn requires compatible, specific end-group functionalization of the CP. Although the CTCP mechanism allows for a wide variety of functional end-groups such as amines, 23 thiols, 24 phosphonic acids, 25 cyanoacrylic acid, 26 and trialkoxysilanes, 27 the process of finding a suitable end group that must furthermore be compatible with the actual polymerization reaction (Murahashi, Kumada-Tamao, Negishi, Suzuki−Miyaura, Kosugi-Migita-Stille, etc.) is often very tedious and time-consuming (Figure 1).…”

Chiral gold–PPA nanocomposites with tunable helical sense and morphology

“…Hybrid nanomaterials 1,2 had become a very important area in nanoscience thanks to the synergistic combination of the properties of their building blocks. In this way, new nanoengineered materials with morphological diversity and potential applications in photonics, 3 optics, 4 asymmetric catalysis, 5 selective separation, 6 chiral sensing and recognition 7 and drug delivery, 8 have been described. Gold nanoparticles (AuNPs) have been widely employed as inorganic building blocks to form these nanocomposites.…”