# Insights into the Imprinting and Rebinding Performance of Molecularly Imprinted Hybrids for Bisphenol A and Bisphenol F

## TL;DR

This study explores how different molecular structures affect the performance of imprinted materials in binding bisphenol compounds.

## Contribution

The study reveals how structural features of bisphenols influence imprinting and rebinding in molecularly imprinted hybrids.

## Key findings

- BPA shows the strongest imprinting performance with high adsorption capacity and selectivity.
- Structural features like p-OH and CH3 groups enhance BPA's binding through multiple interactions.
- 2BPF and 4BPF have lower imprinting performance due to hindered interactions.

## Abstract

This study investigates the factors influencing the imprinting
performance of molecularly imprinted hybrids (MIHs) with various template/monomer
associations and their corresponding adsorption ability for three
bisphenol analogues, bisphenol A (BPA), 2,2′-bisphenol F (2BPF),
and 4,4′-bisphenol F (4BPF). Styrene (St) and methacrylic acid
(MAA) were selected as the primary functional monomers for template
complexation. Compared with hydrophilic MAA monomers, hydrophobic
St monomers were more favorable for BPA imprinting, despite the lower
binding energy of π–π interactions compared to
hydrogen bonds. However, St monomers were unsuitable for 4BPF imprinting,
while 2BPF exhibited limited complexation with MAA monomers. Among
the bisphenols, BPA demonstrated the strongest imprinting capability,
leading MIHs to exhibit the highest imprinting factor (IF = 14–18),
adsorption capacity (Qmax = 43.7–47.6
mg/g), binding affinity (KL = 4.52–6.74
L/mg, ΔHads° = −35.2 to −38.9 kJ/mol,
and ΔSads° = −40.5 to −50.6 J mol–1 K–1), and selectivity over 2BPF
and 4BPF (2.0–3.5). In contrast, 2BPF- and 4BPF-imprinted hybrids
exhibited significantly lower adsorption capacities (Qmax = 19.4–26.7 mg/g) and binding affinities (KL = 1.22–4.35 L/mg) for their respective
templates. In competitive adsorption systems, bisphenol rebinding
followed the trend BPA > 2BPF > 4BPF, regardless of which template
was used for imprinting. Based on NMR analysis, the superior structure-directing
and competitive rebinding abilities of BPA are attributed to the restricted
rotation of its two phenyl groups, p-OH groups, and
additional -CH3 groups on the bridged carbon, which enhance
π–π stacking, H-bond, CH−π, and hydrophobic
interactions within the imprinted cavities. In contrast, the o-OH groups of 2BPF and the rotational phenyl groups of
4BPF hinder their imprinting and rebinding via H-bond and π–π
interactions, respectively.