One-pot synthesis and characterization of novel boronates for the growth of single crystals with nonlinear optical properties

Novel boronates were synthesized by the single step reaction of 2,4-pentanedione, aminophenol and phenylboronic acid in good yield. X-ray diffraction analysis showed that the compounds crystallized in noncentrosymmetric space groups, which was used for the growth of organic crystals with luminescent and nonlinear optical properties. For some boronates it was possible to obtain mm scale single crystals which displayed good transparency from 550 to 1200 nm. These crystals exhibited efficient second-order nonlinearity (second-harmonic generation) and third-order nonlinearity (two-photon excited fluorescence). In the case of second-harmonic generation, the observed effect was four times larger than that generated by urea which was used as a reference. Additionally, the crystals were used to prepare aqueous colloidal nanocrystals that exhibited superior fluorescence properties than those of the boronates when dissolved in organic solvents. Finally, the thermal stability of single crystals was determined using TG and TGA.