Electrostatic potential effects of β-cyclodextrin on optical properties of the 4-dimethyl-aminobenzonitrile

Effects of the electrostatic potential on absorption spectra of the 4-dimethyl-aminobenzonitrile (DMAB) were analyzed theoretically by methods based on the density functional theory. The electrostatic potential was imposed by three different ways: (a) applying a uniform electric field, (b) immersing the system within the cavity of the beta-cyclodextrin (BCD), (c) immersing the system in a cavity built with a charges set that fit to the electrostatic potential generated by the BCD, (d) a superposition of (b) or (c) with a continuum solvent model. The DMAB absorption spectra were estimated using the time dependent density functional theory with the Perdew, Burke, and Ernzerhof exchangecorrelation functional. Additionally, to obtain the correct asymptotic behavior on the corresponding potential the van Leeuwen and Baerends proposal was used. The basis set effect on the predictions was estimated by comparing the TZVP and TZVP plus one additional diffuse function. We found that optical properties of the DMAB are modified in an important way if this system is immersed in an electrostatic potential imposed in several ways. By contrasting our theoretical results with the experimental observations we found that the effect observed on an optical sensor, designed with the BCD, and on the DMAB..BCD inclusion complex is due mainly by the electrostatic potential generated by the BCD. (c) 2012 Wiley Periodicals, Inc.