Theoretical Studies of Solvent Effects on the Electronic Properties of 1, 3-Bis [(Furan-2-yl) Methylene] Urea and Thiourea

The synthesis and characterization of 1, 3-bis [(furan-2-yl) methylene] urea (BFMU) and 1, 3-bis [furan-2-yl) methylene] thiourea (BFMT) have been reported by our research team. The effects of solvents polarity on their electronic transition energies (HOMO-LUMO) and associated qualitative structure activity relationship parameters (i.e. log P, ionization energies and global hardness) were investigated in this study. The lower HOMO-LUMO energy gap values of BFMT (3.42 - 3.76 eV) in the solvents of choice (water, ethanol, toluene and dimethylsulphoxide) is an indication of higher distribution of charges and probability of higher activities of BFMT relative to BFMU with energy gap in the range: 4.27 - 4.54 eV. From the frontier molecular orbital study of BFMU, the HOMO centers over the entire molecule.  However, the π- electrons of the LUMO are also over the entire molecule except one of the furan rings. Similar trends was observed for the HOMO of BFMT with electron delocalization excluding one of the furan ring, while the LUMO π- electrons system are more localized on the C=N, C=O and C-S bonds than the furan rings. These attest to the charge transfer (CT) characteristic properties of the compounds in the studied solvents. The logPoctanol/water values for the studied compounds which are less than 3, pointed to their usefulness in industrial development especially for agrochemical products.