Complexation of Lignin Dimers with β-Cyclodextrin and Binding Stability Analysis by ESI-MS, Isothermal Titration Calorimetry, and Molecular Dynamics Simulations

Kimberly R. Dean, Brian Novak, Mahsa Moradipour, Xinjie Tong, Dorel Moldovan, Barbara L. Knutson, Stephen E. Rankin, Bert C. Lynn

Research output: Contribution to journalArticlepeer-review

Abstract

Lignin derived from lignocellulosic biomass is the largest source of renewable bioaromatics present on earth and requires environmentally sustainable separation strategies to selectively obtain high-value degradation products. Applications of supramolecular interactions have the potential to isolate lignin compounds from biomass degradation fractions by the formation of variable inclusion complexes with cyclodextrins (CDs). CDs are commonly used as selective adsorbents for many applications and can capture guest molecules in their internal hydrophobic cavity. The strength of supramolecular interactions between CDs and lignin model compounds that represent potential lignocellulosic biomass degradation products can be characterized by assessing the thermodynamics of binding stability. Consequently, the inclusion interactions of β-CD and lignin model compounds G-(β-O-4′)-G, G-(β-O-4′)-truncG (guaiacylglycerol-β-guaiacyl ether), and G-(β-β′)-G (pinoresinol) were investigated empirically by electrospray ionization mass spectrometry and isothermal titration calorimetry, complemented by molecular dynamics (MD) simulations. Empirical results indicate that there are substantial differences in binding stability dependent on the linkage type. The lignin model β-β′ dimer showed more potential bound states including 1:1, 2:1, and 1:2 (guest:host) complexation and, based on binding stability determinations, was consistently the most energetically favorable guest. Empirical results are supported by MD simulations that reveal that the capture of G-(β-β′)-G by β-CD is promising with a 66% probability of being bound for G-(β-O-4′)-truncG compared to 88% for G-(β-β′)-G (unbiased distance trajectory and explicit counting of bound states). These outcomes indicate CDs as a promising material to assist in separations of lignin oligomers from heterogeneous mixtures for the development of environmentally sustainable isolations of lignin compounds from biomass fractions.

Original languageEnglish
Pages (from-to)1655-1667
Number of pages13
JournalJournal of Physical Chemistry B
Volume126
Issue number8
DOIs
StatePublished - Mar 3 2022

Bibliographical note

Funding Information:
This work was supported by the National Science Foundation through grant OIA 1632854 from the Established Program to Stimulate Competitive Research Track 2.

Publisher Copyright:
© 2022 American Chemical Society. All rights reserved.

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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