Planar Chiral[2.2]Paracyclophane-Based Zr(IV)Metal-Organic Frameworks

Self-assembly has been widely explored to improve the circularly polarized_(lum)inescence(CPL)activities of molecular chromophores,but it is hard to amplify CPL while maintaining strong emissions.Optically pure,planar-chiral[2.2]paracyclophane(pCp)is one of the most important sources of chirality for electronic and optoelectronic materials,but the photo_(lum)inescence of its derivatives is significantly quenched after forming aggregates.Here we demonstrate that reticulation of pCp chromophores into highly stable Zr(IV)metal-organic frameworks(MOFs)can simultaneously boost the dissymmetry factor(|g_(lum)|)and_(lum)inescence efficiency(Φ_(PL)).Functionalization of pCp enables the synthesis of two tetracarboxylate linkers with different side arms,which are assembled into two highly stable Zr-MOFswith different topological structures.Geometrical constraints and segregated arrangements of the pCp chromophores imposed by the framework inhibit the aggregation-caused quenching effect and boost their CPL behaviors.Both Zr-MOFs display strong CPL emissions,affording|g_(lum)|andΦ_(PL)values of up to 8.3×10^(-3)and 87%,respectively,which are amplified by∼18-and 52-fold compared to the corresponding free ligands.This work highlights the potential of optimizing CPL performances of chiral chromophores by using MOFs as support structures.

A meso–molecular muscle based on copillar[5]arenes

A meso–molecular muscle was prepared by capping the[c2]daisy chain based on a mono-functionalized copillar[5]arene with an imidazolium group in its axle.From its crystal structure,we observed that it was a cyclic dimer composed of two mirror image subcomponents,a pR-and a pS-copillar[5]arene.Their conformations were fixed by the doubly interlocked mechanical bond.By comparison of the^1H NMR and COSY spectra,we found that the length of this meso–molecular muscle could be controlled not only by the solvents,but also by the counter anions.

Rhodium-Catalyzed Pyridine-Assisted C-H Arylation for the Synthesis of Planar Chiral Ferrocenes

Planar chiral ferrocenes are widely applied in organic synthesis,materials science,and medicinal chemistry,but their synthesis is not trivial.Herein,a highly efficient synthesis of planar chiral ferrocene-based pyridine derivatives via Rh(I)-catalyzed direct coupling of pyridylferrocenes with aryl halides was developed.Good yields and excellent enantioselectivity(95–>99%ee)are obtained for a wide range of substrates.The compatibility of gram-scale synthesis and relatively low catalyst loading(down to 1 mol%based on[Rh])enhance the practicality of the current method.The generated coupling products can be readily transformed into chiral ligands.Mechanistic studies suggest that the C–H bond cleavage of pyridylferrocene may be a reversible step and not the rate-determining step.Significant nonlinear effects indicate the existence of multiple metals or ligands in the active catalyst.

Synthesis of planar chiral isoquinolinone-fused ferrocenes through palladium-catalyzed C-H functionalization reaction

(S,S)-Me-BI-DIME/Pd(0)-catalyzed ennantioselective C-H functionalization of N-ferrocenyl o-bromobenzanilides has been realized,affording isoquinolinone-fused ferrocenes with up to 97% ee.The products can be transformed into planar chiral ferrocenyl monophosphines,which demonstrate their preliminary application.

Highly efficient catalysts derived from planar chiral ferrocenes for asymmetric transfer hydrogenation of ketones

Planar chiral ferrocenes 1 and its diastereoisomer 2 were found to be good lig-ands for. the ruthenium catalyzed asymmetric transfer hydrogenation of ketones with i-PrOH as hydrogen source under refluxing in the presence of sodium hydroxide. The results showed that the absolute configuration of alcohol seemed to be governed by the central chirality in the oxazoline ring instead of the planar chirality. At a ratio of 1:2 for Ru:ligand, 3000:1 S/C and >100,000/h?1 TOF were observed for acetophenone. For propiophenone 99% yield and 85% e.e. were obtained.

Synthesis of Planar-Chiral[2.2]Paracyclophane-Based Oxazole-Pyrimidine Ligands and Application in Nickel-Catalyzed 1,2-Reduction ofα,β-Unsaturated Ketones

The planar-chiral ligands have been widely applied as a class of unique and significant ligands in asymmetric catalysis.Among them,chiral[2.2]paracycyclophane has emerged as a privileged type of planar-chiral framework and has been utilized as an important toolbox due to their structural stability.Herein,we design and synthesize[2.2]paracyclophane-derived oxazole-pyrimidine ligands(abberviated as PYMCOX).These N,N-ligands with stable properties,rigid structure and large steric hindrance performed successfully in nickel-catalyzed asymmetric 1,2-reduction ofα,β-unsaturated ketones,affording the chiral allylic alcohols with up to 99%yield and 99%ee.Meanwhile,this reduction reaction could be conducted on gram-scale without loss of activity and enantioselectivity,and the chiral ligand could be conveniently recovered with high yield.

Chiral pillar[n]arenes:Conformation inversion,material preparation and applications

Chiral pillar[n]arenes have shown great research value and application prospect in construction of chiral materials and chiral applications,due to their inherent planar chiral configurations,chiral recognition ability,easy modification and highly symmetric hydrophobic cavity.This review systematically summarized the conformation inversion factors of planar chiral pillar[5]arenes(pR/p S),such as solvents,temperature,substituent size,alkyl chains,chiral and achiral guest molecules.We firstly introduced the applications of chiral pillar[n]arenes for constructing chiral materials and pointed out that planar conformation inversion showed a great potential role in constructing chiral materials.Then,we mainly concluded the chiral applications of chiral and planar chiral pillar[n]arenes like chiral enantiomer analysis by circular dichroism,electrochemistry or chiral fluorescence sensing.From this review,we found that the inherent planar chiral conformation of chiral pillar[n]arenes have played a very important role in chiral field in the future.