Quantum chemical analyses over benzothiazolines and their boron complexes are performed. In calculations, M06-2X method was selected with 6-31 + G(d,p) level. Structural and spectral (IR and NMR) characterization of studied compounds are done in detail. Quantum chemical descriptors (QCDs) are calculated to investigate the optical properties. Furthermore, molecular electrostatic potential (MEP) maps of the studied compounds are calculated by using electro-static potential (ESP) charges. According to QCDs and MEP maps, NW properties of boron complexes are more than those of benzothiazolines and (Z)-2-((pyridin-2-ylmethylene)amino) benzenethiolatebutane-1,3-bis(olate)boron(III), complex (7), has the most NLO activity in studied compounds. Finally, solvent effect on NW activity are investigated by calculating UV-vis spectrum in gas phase (epsilon = 1), toluene (epsilon = 2.3741), chloroform (epsilon = 4.7113), methanol (epsilon = 32.613), water (epsilon = 78.3553) and nmethylformamide-mixture (epsilon = 181.56). According to these spectra results, NLO activity mainly increases with increasing of polarizability of media. (C) 2018 Elsevier B.V. All rights reserved.