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CommentInterest in D,L-aspartic acid has spanned several decades, from the first structural determination by Rao (1973), due to its acting as important ligand in the preparation of transition metal complexes (Ciunik, 1987;Casellato et al., 1991;Barfod et al., 1999). In exploring the possibility of introducing D,L-aspartic acid into a phosphite system, we unexpectedly obtained the title compound. To the best of our knowledge, there are only four reports on the structure of D,L-aspartic acid (Rao et al., 1968;Rao, 1973;Sequeira et al., 1989;Flaig et al., 1998). The present structure of D,L-aspartic acid differs slightly from these previously reported ones, since it presents the same space group and a similar molecular disposition, but with an a parameter some 7-8% shorter.The molecules (Fig. 1) are interconnected with each other by hydrogen bonds to form a 3-D supramolecular network (Table 1 and Fig. 2). ExperimentalThe title compound was obtained by hydrothermal methods. A mixture of Zn(CH 3 COO) 2 ·2H 2 O (0.16 g), H 3 PO 3 (0.19 g), D,L-aspartic acid (0.25 g) and H 2 O (8 ml), was sealed in a 25 ml Teflon-lined steel autoclave and heated under autogenous pressure at 363 K for 3 days. Then, the filtrate was kept at room temperature and colorless prism-like crystals were obtained after three weeks. RefinementAll the H atoms were located from difference-density maps in a difference Fourier map and their positions and isotropic displacement parameters were refined.

ABSTRACT:The hydrogen bonding of complexes formed between the formamide and uracil molecule has been fully investigated in the present study using the density functional theory (DFT) method at varied basis set levels from 6-31G to 6-311ϩϩG(d,p). Eight stable cyclic structures with two hydrogen bonds involved in the interaction are found on the potential energy surface (PES). The four structures are seven-membered rings; the others are eight-membered rings. The eight-membered ring is preferred over the seven-membered one by analyzing the hydrogen bond lengths and the interaction energies. The infrared (IR) spectrum frequencies, IR intensities, and the vibrational frequency shifts are reported.