Infrared, Raman and electronic spectra of alanine: A comparison with ab intio calculation

Synthesis and characterization of mixed ligand complexes of lomefloxacin drug and glycine with transition metals. Antibacterial, antifungal and cytotoxicity studies

“…The IR spectra of the free LFX and glycine ligands and their metal complexes were carried out in the range of 4000-400 cm À1 and the most effective bands are listed in Table 2. The strong band observed at 1725 cm À1 in the free LFX ligand is assigned to the carbonyl stretching vibration [24][25][26]. This band is found in the spectra of the complexes at 1721-1739 cm À1 (Table 2) Table 2).…”

“…However, the data are retained in Table 2 for clarity. Therefore, from the IR spectral studies, it is concluded that LFX behaves as a neutral bidentate ligand with OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen [24][25][26][27][28]. Glycine behaves as a uninegative bidentate ligand with NO donor sites and coordinated to the metal ions via the amino group N and deprotonated carboxylic oxygen.…”

Population and Interconversion of Neutral and Zwitterionic Forms of L-Alanine in Solution

“…After optimization, a single local minimum for Z-Ala was located at the HF/6-31+G(d) level of theory, but no stationary point was found at the B3LYP/6-31+G(d) level of theory, as seen previously. 13 The transition state (TS) between N-Ala and Z-Ala was located using the Synchronous Transit and Quasi-Newton (STQN) method 29 with the QST3 option of the Gaussian 03 30 at the HF/6-31+G(d) level of theory. N-Ala with a similar configuration of amino and carboxylic groups to Z-Ala was chosen as initial structure in generating the TS structure.…”

“…22,23 For most of the previous works in solution, solvents were considered as a continuum and the self-consistent reaction field (SCRF) methods were employed to calculate solvation free energies. 13,14,16,22,23 A few works have adopted the models of zwitterionic [17][18][19][20] or neutral 20 alanine with explicit waters embedded in a SCRF.…”

“…In particular, the zwitterionic alanine can be located as a local minimum at the HF/6-31G(d) level of theory, but it is not a local minimum at B3LYP/6-31+G(d) and B3LYP/6-311++G(d,p) levels of theory. 13 It was suggested that at least two water molecules are needed to form a stable alanine zwitterion-water cluster in the gas phase. 20 The zwitterionic form was found to be more stable than the neutral form when the solvation shell reaches eight water molecules.…”