Terminal‐vinyl liquid crystal crown ether‐modified, vinyl‐functionalized hybrid silica monolith for capillary electrochromatography

Abstract

A novel terminal-vinyl liquid crystal crown ether (2-[4-(3-undeceny-1-yloxy)-phenyl]-2-[4'-(4'-carboxybenzo-15-crown-5)-phenyl] propane) (LCCE) was synthesized and used to modify hybrid silica-based monolithic column possessing vinyl ligands for CEC. The monolithic silica matrix containing vinyl functionalities was prepared by in situ co-condensation of tetramethoxysilane and vinyl-trimethoxysilane via sol-gel process and chemically modified with LCCE by free radical polymerization procedure using alpha,alpha'-azobisisobutyronitrile as an initiator. Morphology of the monolithic column was examined by SEM and mercury porosimetry and the successful incorporation of terminal-vinyl LCCE to the vinyl-hybrid monolith was characterized by infrared spectra. Polycyclic aromatic hydrocarbons, benzenediols, carbamate pesticides and steroids, were successfully separated on the column. The separations were dominated hydrogen bonding supplied by crown ether and hydrophobic interaction offered by the liquid crystal. The effect of ACN concentration on separation performance was studied and the result indicated that RP retention mechanism played an important role. Reproducibilities of migration times for the six selected polycyclic aromatic hydrocarbons were reasonable, with relative standard deviation less than 3.50% for five consecutive within-column runs and were 8.38-9.11% for column-to-column measurements of three columns.

One‐pot synthesis of a new high vinyl content hybrid silica monolith dedicated to nanoliquid chromatography

“…For the same solutes and a less eluting mobile phase containing 50% of acetonitrile, Feng et al. observed no retention on a vinyl hybrid monolith prepared with a lower ratio of organosilane.…”

“…To the best of our knowledge, it is the highest efficiency reported for a hybrid monolithic column in nano‐LC. Previously reported vinyl hybrid monoliths (post modified or not), afforded between 80 000 and 110 000 plates/m when evaluated in CEC. In nano‐LC (where radial or longitudinal structural heterogenities of the stationary phase are more critical), the best efficiencies reported for hybrid monoliths (allyl, phenyl) range from 37000 to 120 000 plates /m .…”

Capillary Electrochromatography with Liquid Crystal Crown Ether Modified Hybrid Silica Monolith for Analysis of Imidacloprid and Carbendazim in Tomatoes

“…24 as the bonded phase of hybrid silica monolith exhibit superior performance due to their host-guest recognition.…”

Recent advances in silica‐based monoliths: Preparations, characterizations and applications

“…In an attempt to prepare a hybrid silica‐based monolith for CEC applications, Feng et al 46 synthesized a novel terminal‐vinyl liquid crystal crown ether (LCCE), namely 2‐[4‐(3‐undecen‐1‐yloxy)‐phenyl]‐2‐[40‐(40‐carboxybenzo‐15‐crown‐5)‐phenyl] propane for further use in the modification of a hybrid silica‐based monolithic column possessing vinyl ligands 46. The monolithic silica matrix containing vinyl functionalities was prepared by in situ co‐condensation of tetramethoxysilane (TMOS) and vinyl‐trimethoxysilane via sol–gel process and chemical modification with LCCE by free radical polymerization procedure using α,α'‐azobisisobutyronitrile (AIBN) as an initiator.…”