Raman and infrared spectra and theoretical calculations of dipicolinic acid, dinicotinic acid, and their dianions

Analysis of the Raman spectra of Ca2+-dipicolinic acid alone and in the bacterial spore core in both aqueous and dehydrated environments

“…1. 24,34,35 The DPA molecule consists of a pyridine ring and two carboxyl groups. In DPA in solution at pH 8.0, the two carboxyl groups are likely ionized (COO À ), although there are monovalent counterions provided by the Tris buffer.…”

“…Previous work has shown that the vibrational frequencies of DPA can be strongly affected not only by its structure but also by surrounding molecules, since the carboxylic acid groups of DPA are involved in strong intermolecular interactions with water or neighboring DPA molecules in solution or crystals. 24,35 The DPA crystal may be formed as dipicolinic acid monohydrate (DPA$H 2 O) and there is extensive hydrogen bonding between the carboxylic acid groups of adjacent DPA molecules. 35 (3) There are no notable frequency differences in Raman spectra of CaDPA in solution, or as dry powder or crystals, as shown in Fig.…”

“…24,35 The DPA crystal may be formed as dipicolinic acid monohydrate (DPA$H 2 O) and there is extensive hydrogen bonding between the carboxylic acid groups of adjacent DPA molecules. 35 (3) There are no notable frequency differences in Raman spectra of CaDPA in solution, or as dry powder or crystals, as shown in Fig. 2(a)-(c) and (h), except that crystalline CaDPA exhibits a double peak at 1575 cm À1 with the peak shifted to 1587 cm À1 (the ring stretch band).…”

Thermal investigation and infrared evolved gas analysis of light lanthanide(III) complexes with pyridine-3,5-dicarboxylic acid

“…The most characteristic bands and their assignments are given in Table 1 [33,34]. The spectrum of dinicotinic acid shows strong band at 1721 cm À1 originating from stretching vibrations of carbonyl group n(C5 5O).…”

Experimental (FTIR and FT-Raman) and theoretical investigation of some pyridine-dicarboxylic acids

“…Monomeric and dimeric structures of 3,5-pyridine-dicarboxylic acid or dinicotinic acid were studied by Nataraj et al by recording FT-Raman, FTIR and UV spectra and making DFT and ab initio calculations [14]. Dipicolinc acid, dinicotinic acid and their dianions were investigated, both experimentally (Raman and infrared spectra) and theoretically, by Kathleen McCann and Jaan Laane [15], whereas its Raman spectra in microcrystalline form was reported by Alexandre et al [16]. Thermochemical and theoretical studies of 2,3-; 2,5-; and 2,6-pyridine-dicarboxylic acids are also available along with that of dimethyl pyridine-2,6-dicarboxylate [17].…”