Cyclic versus straight chain oligofuran as sensor: A detailed DFT study

Abstract

This study is a novel approach for exploring the sensitivity and selectivity of cyclic oligofuran (5/6/7CF) toward gaseous analytes and their comparison with straight chain analogues (5/6/7SF). The work is not only vital to understand the superior sensitivity but also for rational design of new sensors based on cyclic ring structures of oligofuran. Interaction of cyclic and straight chain oligofuran with NH3, CO, CO2, N2H4, HCN, H2O2, H2S, CH4, CH3OH, SO2, SO3 and H2O analytes is studied via DFT calculation at B3LYP-D3/6-31++G (d, p) level of theory. The sensitivity and selectivity are illustrated by the energetic parameters (Ebind, SAPT0 energies, NCI analysis) electronic properties (H-L gap, percentage of average energy gap, CHELPG charge transfer, DOS spectra) and UV-Vis analysis. All these properties are simulated at B3LYP/6-31G (d) level of theory while UV-Vis is calculated at TD-DFT method. Cyclic oligofuran has high binding energy with analytes compared to 5/6/7SF which corresponds the higher sensitivity of 5/6/7CF. Furthermore, the cyclization of oligofuran significantly improve the sensitivity and selectivity of the system. Alteration in electronic properties of 5/6/7CF and 5/6/7SF is remarkably high upon complexation with SO2 and SO3. Further the stability of rings (5, 6 and 7 membered cyclic oligofurans) and their SO3 complexes is also confirmed by molecular dynamics calculations. The finding of the work clearly suggests that the cyclic geometry enhances not only sensitivity but also selectivity of conducting polymers (oligofuran).

DOI: 10.1016/j.jmgm.2020.107569