Crystal Structure and Strong Piezoelectricity of New Amino Acid Based Hybrid Crystals: [H-β-(3-Pyridyl)-Ala-OH][ClO₄] and [H-β-(4-Pyridyl)-Ala-OH][ClO₄]

The new amino acid based [H-β-(3-pyridyl)-Ala-OH]­[ClO4] and [H-β-(4-pyridyl)-Ala-OH]­[ClO4] crystals were synthesized, and their structure and functional piezoelectric properties were investigated in detail. Both analogs crystallize in the polar, piezoelectric P21 space group. Piezoresponse force microscopy (PFM) measurements revealed that shear piezoelectric coefficient of [H-β-(3-Pyridyl)-Ala-OH]­[ClO4] crystal is more than twice that in the widely used transducer material lithium niobate, LiNbO3. The crystal structures of both perchlorate derivatives were determined, and the influence of the inter- and intramolecular hydrogen bond network on piezoelectricity of crystals were discussed. The existence of the intramolecular hydrogen bonding was confirmed by means of IR spectroscopy measurements. Thermogravimetric (TGA) technique was applied to study the thermal behavior of title crystals