Growth and characterization of D-Alanine DL-Mandelic acid single crystals for antibacterial activity and optical limiting applications

Abstract

A promising optically prospective D-Alanine DL-Mandelic acid (DADLMA) an organic single crystal was successfully grown at room temperature by a slow solvent evaporation approach. The monoclinic crystal structure of the title crystal with space group C2 has been verified. The existence of multiple operational groups and linkages in the DADLMA crystal was ensured with the FTIR spectrum. The grown crystal was investigated to determine optical absorption cut-off wavelength (274 nm), energy band gap and linear refractive index by the UV–Visible absorption spectrum. The luminescence response has been observed to probe the compatibility of the material for the production of optical devices and the grown crystal shows a peak at 570 nm. The major focus of our work was to determine NLO properties of the sample and the DADLMA crystal was investigated for the first attempt by Z-scan measurement to bring out third-order nonlinear optical properties. The determined values are β (0.0149 × 10-4 cm/W), n2 (3.351 × 10-10 cm2/W) and χ(3) (1.674 × 10-7esu). The antibacterial activity of the title compound was investigated against a few foodborne pathogens (Streptococcus aureus, Klebsiella pneumoniae, Streptococcus pneumoniae and Escherichia coli) by measuring the zone of inhibition. Existing data indicate that the synthesized crystals are potential candidates for opto-electronic devices, optical limiting devices and biological applications.