High-density information storage in an absolutely defined aperiodic sequence of monodisperse copolyester

Synthesis of a polymer composed of a large discrete number of chemically distinct monomers in an absolutely defined aperiodic sequence remains a challenge in polymer chemistry. The synthesis has largely been limited to oligomers having a limited number of repeating units due to the difficulties associated with the step-by-step addition of individual monomers to achieve high molecular weights. Here we report the copolymers of ??-hydroxy acids, poly(phenyllactic-co-lactic acid) (PcL) built via the cross-convergent method from four dyads of monomers as constituent units. Our proposed method allows scalable synthesis of sequence-defined PcL in a minimal number of coupling steps from reagents in stoichiometric amounts. Digital information can be stored in an aperiodic sequence of PcL, which can be fully retrieved as binary code by mass spectrometry sequencing. The information storage density (bit/Da) of PcL is 50% higher than DNA, and the storage capacity of PcL can also be increased by adjusting the molecular weight (~38???kDa)

Sequence-defined multifunctional polyethers via liquid-phase synthesis with molecular sieving

Synthetic chemists have devoted tremendous effort towards the production of precision synthetic polymers with defined sequences and specific functions. However, the creation of a general technology that enables precise control over monomer sequence, with efficient isolation of the target polymers, is highly challenging. Here, we report a robust strategy for the production of sequence-defined synthetic polymers through a combination of liquid-phase synthesis and selective molecular sieving. The polymer is assembled in solution with real-time monitoring to ensure couplings proceed to completion, on a three-armed star-shaped macromolecule to maximize efficiency during the molecular sieving process. This approach is applied to the construction of sequence-defined polyethers, with side-arms at precisely defined locations that can undergo site-selective modification after polymerization. Using this versatile strategy, we have introduced structural and functional diversity into sequence-defined polyethers, unlocking their potential for real-life applications in nanotechnology, healthcare and information storage

Advances in Catalytic Enantioselective Fluorination, Mono-, Di-, and Trifluoromethylation, and Trifluoromethylthiolation Reactions

Fluorine is the most electronegative element in the periodic table, and the introduction of one or more fluorine atoms into a molecule can result in greatly perturbed properties. Methods to introduce fluorine into small organic molecules have been actively investigated for many years by specialists in the field of fluorine chemistry. The earliest advances in catalytic asymmetric fluorination were made by exploiting transition metal enolates, capable of a bidentate mode of coordination to a metal. In 2002, Sodeoka and coworkers reported the enantioselective fluorination of β-ketoesters catalyzed by a chiral palladium complex. In 2005, Shibata and co-workers reported enantioselective chlorination and fluorination of carbonyl compounds capable of two-point binding. In 2011, Gade and co-workers described the synthesis of a new class of chiral tridentate N-donor pincer ligands, bis(oxazolinyl-methyldiene)isoindolines