DFTr studies of five- and six-residue cyclic-β(1→4) cellulosic molecules

Area of Science:

• Computational chemistry
• Carbohydrate chemistry
• Biophysics

Background:

• Density functional theory (DFT) studies reveal energy preferences in cellobiose conformations.
• Larger cellulosic fragments enable stable low-energy structures through inter-residue hydrogen bonding.

Purpose of the Study:

• To investigate the stability of cyclic anti-conformations in β-linked cellulosic molecules.
• To compare the energy of cyclic structures with linear chains using implicit solvation methods.

Main Methods:

• Energy optimization of five- and six-residue cyclic β-linked molecules.
• Utilized the Conductor-like Solvation Model (COSMO) with B3LYP DFT.
• Implicit solvation in water and n-heptane was employed.

Main Results:

• Symmetric cyclic structures remained undistorted after optimization.
• Optimized cyclic conformations were lower in energy than linear chains (post-cyclization energy correction).
• Observed strong synergistic tendencies due to hydrogen bonding networks in cyclic structures.

Conclusions:

• Cyclic cellulosic structures can adopt stable, low-energy conformations.
• Energetically unfavorable flipped conformations in water present significant synthetic challenges.
• Understanding conformational preferences is key for designing and synthesizing novel cellulosic compounds.