Binding of calcium to amino acids: the crystal structure of pentaaquobis(hydroxy-(L)-prolinato)calcium, Ca(C5H8O3N)2.5H2O

Molecular modelling, spectroscopic characterization and nonlinear optical analysis on N-Acetyl-DL-methionine

“…C-C bond lengths in the range of ∼ 1.509 − 1.546Å are also close to the experimental bond lengths in the range of ∼ 1.483 − 1.531Å, varying with a little difference. In the title compound, the carbon sulfur bond lengths C6-S and C7-S are 1.833Å and 1.827Å with B3LYP and 1.814Å and 1.809Å with HSEH1PBE while the reported values are in the range ∼ 1.764 − 1.796Å [25,26]. As discussed by Johnson et al, the various DFT methods predict bond lengths, which are systematically too long (30).…”

“…In 1985, the crystal structure of NAM has been reported by Ponnuswamy and Trotter [25] and five years later, redetermined it and its calcium adduct viz., Ca(N -acetyl-DLmethionine) 2 . H 2 O by Kim and Eriks [26]. Moovendaran and Natarajan reported structure and some other properties by recording X-ray, IR, UV-Vis-NIR, TGA/DTA, and photoluminescence spectra [27].…”

“…For the compound, we have employed a 6-311++G(d,p) basis set at B3LYP and HSEH1PBE levels without symmetry constrain, to provide integrity and compared computed geometry parameters through experimental bond lengths and bond angles, which are taken from Refs. [25,26]. The atom numbering scheme for the molecule is shown in Fig.…”

“…About the X-ray data, the bond angle C2-N-C3 is ∼ 121.2 • , whereas it is computationally 128.0 • and 127.4 • with B3LYP and HSEH1PBE methods, respectively, which provide the possibility of the presence of hydrogen bond. According to literature [25,26]…”

Crystal structures of coordination polymers from CaI2and proline

“…These are coordination polymers and networks based on calcium chloride and bromide with both l-proline and dl-proline. The other two structures are a molecular complex with deprotonated N,O-chelating hydroxyproline (Kim et al, 1985), and a coordination network of calcium pyroglutamate (Schmidbaur et al, 1991).…”