A new class of network‐polymeric chiral stationary phases

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Abstract
A strategy based on the use of homo bi‐ and multifunctional building blocks for the synthesis of a new class of network‐polymeric chiral stationary phases has been evaluated. The key steps comprise acylation of N,N′‐diallyl‐L‐tartardiamide (DATD) and reaction with a multifunctional hydrosilane, yielding a network polymer incorporating the bifunctional C2‐symmetric chiral selector. Covalent bonding to a functionalized silica takes place during the latter process. Many of these chiral sorbents show interesting enantioselective properties toward a wide variety of racemic solutes under normal‐phase (hexane‐based) conditions. The retention is mainly caused by the hydrogen‐bonding ability of the analyte, which is regulated by mobile phase additives like alcohol or ether cosolvents. The most interesting chiral stationary phases, in terms of broad enantioselectivity, were obtained from O,O′‐diaryol‐DATD‐derivatives, particularly those containing the 3,5‐dimethylbenzoyl and the 4‐(tert‐butyl)benzoyl moieties. Since high column efficiencies can be obtained with these chiral sorbents, an α‐value of ca. 1.2 is usually sufficient to produce baseline separation. A large number of neutral as well as acidic or basic drug racemates are resolved without derivatization.