Lin Pu

An efficient and practical direct resolution of racemic 1,1′-bi-2-naphthol to both of its pure enantiomers

Abstract An efficient and practical method to directly resolve racemic 1,1′-bi-2-naphthol, rac- 1 , into optically pure R and S- 1 has been developed by modification of a N-benzylcinchonidinium chloride resolution procedure. In a typical experiment, 60 g of rac- 1 is resolved to give 22.5 g of R- 1 (75%, >99% ee) and 21 g of S- 1 (70%, >99% ee). The chiral resolving agent, (8S, 9R)-(−)-N-benzylcinchonidinium chloride, 2 , is recovered in 80% yield.

The first sterically regular chiral conjugated crown ether polymer

Abstract The coupling of (S)-6,6′-dibromo-2,2′-binaphtho-20-crown-6 with 1,4-diethynyl-2,5-dioctadecyloxybenzene in the presence of Pd(PPh3)4 and CuI catalysts leads to the formation of the first sterically regular chiral conjugated crown ether polymer. This polymer is soluble in organic solvents. GPC analysis shows that the molecular weight of this polymer is Mw = 10,500 and Mn = 5,300 (PDI = 2.0). [α]D = 120.9 (c = 0.95, THF). Another soluble crown ether polymer has also been made from the racemic binaphthyl monomers. Its molecular weight is Mw = 27,900 and Mn = 11,500 (PDI = 2.4).

Synthesis of an optically active poly(aryleneethynylene) containing extended conjugation in the repeat unit

Abstract A binaphthyl-based chiral poly(aryleneethynylene) (R)- 9 that contains significantly longer conjugated repeat unit than the previously reported such materials has been synthesized. GPC analysis of (R)- 9 shows that its molecular weight is Mw = 38,200 and Mn = 29,000 (PDI = 1.3). The specific optical rotation of this polymer is [α]D =−288.6 (c = 0.5, CH2Cl2). Although the conjugated repeat unit of (R)- 9 contains a total of 54 π electrons, this polymer is still soluble in regular organic solvents. The polymer made of racemic binaphthyl units is also prepared.

Characterization of novel optically active conjugated polyarylenes and poly(aryleneethnylene)s by a combination of off-line static and dynamic light scattering with gel permeation chromatography

By combining the offline static and dynamic laser light scattering (LLS) and gel permeation chromatography (GPC) results of a broadly distributed polymer sample, we were able to characterize a series of chiral binaphthyl-based polyarylenes and poly(aryleneethnylene)s in THF at 25°C. For each of the samples, we obtained not only the weight-average molar mass Mw, the second virial coefficient A2 and the z-average translational diffusion coefficient ,D., but also two calibrations: V 5 A 1 Blog(M) and D 5 kD M 2a D , where V, D, and M are the elution volume, the transla- tional diffusion coefficient and the molar mass for monodisperse polymer chains, re- spectively, and A, B, kD, and aD are four calibration constants. Using these calibrations, we estimated the molar mass distributions of these novel polymers. We showed that using polystyrene to calibrate the GPC columns could lead to a smaller Mw. Our results indicate that all the polymers studied have a rigid chain conformation in THF at 25°C and the introduction of the —NO2 groups into the monomer can greatly promote the polymer solubility in THF.