Validation of computational approach to study monomer selectivity toward the template Gallic acid for rational molecularly imprinted polymer design

Abstract

Gallic acid (GA) is important for pharmaceutical industries as an antioxidant. It also finds use in tanning, ink dyes and manufacturing of paper. Molecularly imprinted polymers (MIP), which are tailor made materials, can play an excellent role in separation of GA from complex matrices. Molecular recognition being the most important property of MIP, the present work proposes a methodology based on density functional theory (DFT) calculations for selection of suitable functional monomer for a rational design of MIP with a high binding capacity for GA. A virtual library of 18 functional monomers was created and screened for the template GA. The prepolymerization template-monomer complexes were optimized at B3LYP/6-31G(d) model chemistry and the changes in the Gibbs free energy (ΔG) due to complex formation were determined on the optimized structures. The monomer with the highest Gibbs free energy gain forms most stable complex with the template resulting in formation of more selective binding sites in the polymeric matrix in MIPs. This can lead to high binding capacity of MIP for GA. Amongst the 18 monomers, acrylic acid (AA) and acrylamide (AAm) gave the highest value of ΔG due to complex formation with GA. 4-vinyl pyridine (4-Vp) had intermediate value of ΔG while, methyl methacrylate (MMA) gave least value of ΔG due to complex formation with GA. Based on this study, the MIPs were synthesized and rebinding performance was evaluated using Langmuir-Freundlich model. The imprinting factor for AA and AAm based MIPs were 5.28 and 4.80 respectively, 4-Vp based MIP had imprinting factor of 2.59 while MMA based MIP exhibited an imprinting factor of 1.95. The experimental results were in good agreement with the computational predictions. The experimental data validated the DFT based computational approach.

Effect of some polymerization methods on the imprinting performance of molecularly imprinted polymers for molecularly imprinted solid-phase extraction application

“…The formation of di-hydrogen bond between the carboxylic acid groups of the GA and AA is the main interaction responsible for the recognition of the GA. [11,12] The MIPs exhibited binding for the structural analogues up to some extent due to the presence of carboxylic group in the structurally similar compounds. However, the variation in the molecular size due to the lacking of one ÀOH group in the structural analogues hindered the accessibility of the imprinting sites.…”

Computational Strategy in Rational Choice of Functional Monomers for "Artificial Receptor" Synthesis on Melamine

“…по-третє, використання квантово-механіч-них методів дає змогу детальніше, чим мето-дами молекулярної механіки, теоретично ви-вчити природу процесів (наприклад, переносу заряду), які можуть відбуваються, зокрема, на етапах синтезу МІПів; по-четверте, квантово-механічний DFT-метод успішно використовувався іншими до-слідниками (але для інших об'єктів) і мав пе-редбачуваний характер [36], у нас не викликає сумнівів адекватність ви-користання DFT-методу для задачі обґрунту-вання вибору функціонального мономеру для «штучного рецептора» на меламін.…”

Rational computational design for the development of andrographolide molecularly imprinted polymer

“…Non-covalent approach has been broadly used due to its easy removal of templates [15]. Because, it can exhibit several possible interactions, such as hydrogen bonds, hydrophobic interactions, van der Waals forces as well as electrostatic interactions [16]. Removal of template results in three dimensional polymeric network exposes cavities that are complementary in terms of size, shape, interaction sites and the coordination of template molecules.…”

“…MIP synthesis is typically a quiet time consuming process which often requires experimental practices through the variation of functional monomers and solvents. Conventionally, selecting optimal imprinting conditions are based on the trial and error approach, which is a tedious method [16]. A better method and understanding on the basic mechanism of imprinting process is necessary to rationally design MIP.…”