Croconic Acid Doped Glycine Single Crystals: Growth, Crystal Structure, UV-Vis, FTIR, Raman and Photoluminescence Spectroscopy

Abstract

Glycine (Gly) single crystals doped with croconic acid (CA) were grown by evaporation from aqueous solutions. Depending on the weight ratio of Gly and CA in solutions, the crystals take on a plate or pyramidal shape. Both powder and single crystal XRD analyses indicate that the crystal lattices of plates (α-Gly:CA) and pyramides (γ-Gly:CA) correspond to the lattices of pure α-Gly and γ-Gly polymorphs, respectively. Raman and FTIR spectra of Gly:CA crystals are very close to the spectra of undoped crystals, but include bands associated with CA impurity. Analysis of UV-Vis absorption spectra indicates that doping does not remarkably change bandgap value Eg~5.2 eV but results in appearance of strong absorption bands in the transparency region of pure glycine crystals, which result from local electronic transitions. Incorporation of CA molecules in Gly creates strong green photoluminescence in a wide spectral range 1.6–3.6 eV. Comparison of the optical spectra of Gly:CA and previously studied TGS:CA crystals indicates that in both cases, the modifications of the optical spectra induced by CA doping are practically identical and are related to the interaction between CA molecules located in the pores of the host Gly crystals and neighboring Gly molecules.

Synthesis and Study of Organic Nanostructures Fabricated by Inclusion of 2-Methylbenzimidazole Molecules in Nanotubes of Chrysotile Asbestos, Mesoporous Silica, and Nanopores of Borate Glasses

“…In connection with the successes in the field of molecular biology and bioengineering is the prospect of creating new devices and systems for medicine, electronics, and energy, based on the possibility of embedding organic, semi-organic, or bioorganic molecules into various structures with nanosized cavities, such as nanopores, nanotubes, and voids in the crystal structure of organic and semi-organic crystals [ 20 , 21 , 22 , 23 , 24 ].…”

“…The inclusion of MBI molecules cannot destroy the material of matrices or the void structure. The penetration of MBI molecules into voids can be followed only by the appearance of hydrogen bonds between ions of the matrix and MBI that cannot affect the matrix material [ 24 ]. Nevertheless, the appearance of such bonds, most probably, can influence the properties of MBI nanocrystals.…”