Multiscale molecular simulations for the solvation of lignin in ionic liquids

Abstract

Lignin, the second most abundant biopolymer found in nature, has emerged as a potential source of sustainable fuels, chemicals, and materials. Finding suitable solvents, as well as technologies for efficient and affordable lignin dissolution and depolymerization, are major obstacles in the conversion of lignin to value-added products. Certain ionic liquids (ILs) are capable of dissolving and depolymerizing lignin but designing and developing an effective IL for lignin dissolution remains quite challenging. To address this issue, the COnductor-like Screening MOdel for Real Solvents (COSMO-RS) model was used to screen 5670 ILs by computing logarithmic activity coefficients (ln(γ)) and excess enthalpies (HE) of lignin, respectively. Based on the COSMO-RS computed thermodynamic properties (ln(γ) and HE) of lignin, anions such as acetate, methyl carbonate, octanoate, glycinate, alaninate, and lysinate in combination with cations like tetraalkylammonium, tetraalkylphosphonium, and pyridinium are predicted to be suitable solvents for lignin dissolution. The dissolution properties such as interaction energy between anion and cation, viscosity, Hansen solubility parameters, dissociation constants, and Kamlet–Taft parameters of selected ILs were evaluated to assess their propensity for lignin dissolution. Furthermore, molecular dynamics (MD) simulations were performed to understand the structural and dynamic properties of tetrabutylammonium [TBA]+-based ILs and lignin mixtures and to shed light on the mechanisms involved in lignin dissolution. MD simulation results suggested [TBA]+-based ILs have the potential to dissolve lignin because of their higher contact probability and interaction energies with lignin when compared to cholinium lysinate.

Accurate prediction of carbon dioxide capture by deep eutectic solvents using quantum chemistry and a neural network

“…† The COSMO files were generated at the BVP86/TZVP/DGA1 level of theory and basis set using the keyword "scrf = COSMORS". 46,47 Further, we performed a search for conformations of HBAs and HBDs using Turbomole 48,49 and BIOVIA COSMOconfX2022 programs (version 22.0.0, COSMOlogic, Leverkusen, Germany), which automatically identify conformers relevant for subsequent COSMO-RS calculations. The COSMO calculations within COSMOConf were performed using the BP-TZVP method and basis set and generated stable COSMO conformers.…”

Quantum Chemistry-Driven Machine Learning Approach for the Prediction of the Surface Tension and Speed of Sound in Ionic Liquids

“…With our independent ion model, we obtained excellent predictions of IL properties with lower deviations and were able to study the importance of ions individually. A potential flaw of the methodology of Járvás et al is the fact that they did not focus on the optimal conformers of the complex of ionic pairs, which can be diverse and difficult to obtain owing to a rugged potential energy surface that is difficult to search. , Considering the ions individually does not suffer from this drawback. In addition, our model is trained (with a lower percentage of data set 55%) and tested (with a higher percentage of data set 45%) on a set of ILs with larger structural diversity and a greater diversity in their functional groups (360) with a greater number of data points (2524).…”

“…To calculate the σ-profiles of ions, first the structures of all the investigated cations and anions were drawn in the Avogadro (version 1.2.0) software, and then the molecular geometries of ions were optimized at the B3LYP level of theory and 6–311++G­(d, p) basis set using the Gaussian09 package. ,, Furthermore, we performed a search for conformations of anions and cations using Turbomole , and BIOVIA COSMOconfX2022 programs (version 22.0.0, COSMOlogic, Leverkusen, Germany), which automatically identify conformers relevant for subsequent COSMO-RS calculations. The COSMO calculations within COSMOConf were performed using the BP-TZVP method and basis set and generated stable COSMO conformers using the heuristic search algorithm. ,− The COSMO conformers with the lowest energies are the most stable conformers. The generated COSMO conformers were then used as input to the BIOVIA COSMOtherm (version 21.0, COSMOlogic, Leverkusen, Germany) package with the BP_TZVP_21 parametrization, which was used to calculate the σ profiles of the cations and anions. , …”

Recent advances in catalytic conversion of lignin to value-added chemicals using ionic liquids and deep eutectic solvents: a critical review

“…It is essential to underscore that both the choice of cation and anion in the IL system play a pivotal role in determining the efficacy of lignin dissolution. 100 Due to the above-mentioned fact about [Ch]Lys, Choudhary et al 101 also employed this IL-processed poplar lignin for hydrogenolysis to guaiacol over a palladium catalyst supported on zirconium phosphate (ZrP). Based on this investigation, it was concluded that the acidity of ZrP contributes to the extensive cleavage of the C–O link.…”