Synthesis, X-ray diffraction analysis, and chemical–optical characterizations of boron complexes from bidentate ligands

Abstract

Herein is reported the synthesis and X-ray diffraction analysis for three boron complexes (2a–2c) prepared from the reaction of bidentate ligands (1a–1c) and diphenylborinic acid. Chemical characterization for the borinates is completed with IR, UV–Vis and NMR techniques, particularly 11B NMR spectra confirmed the formation of boron complexes. X-ray diffraction analysis showed that for compounds 2a and 2c a non-planar conformation for the main π-backbone is acquired after boron complexation; for compound 2b the planar conformation is preserved. Additionally, cubic nonlinear optical (NLO) properties were evaluated, through the optical susceptibility χ(3) (-3ω, ω, ω, ω), using the THG Maker-Fringes technique. Results showed that χ(3) response decreases from ligands to boron complexes; this behavior could be attributed to a structural conformation or deformation of the electronic π-system after boron complexation. The demonstrated electronic and structural features of these borinates could be useful for new strategies in the design of novel NLO dyes.