The crystal structures of the A and B forms of potassium D-gluconate monohydrate by neutron diffraction

Structure of ammonium D-gluconate

“…Other types of bent-chain conformations were found earlier in the monoclinic modification of KC6H 1107. H20 (Panagiotopoulos et al, 1974), in trisodium 6-phospho-D-gluconate dihydrate (Smith, Fitzgerald, Caughlan, Kerr & Ashmore, 1974) and in one of the gluconate ions of Mn(C6HI~O7)2.2H20 (Lis, 1979). The most interesting fact is that contrary to all other ~t-hydroxycarboxylic moieties (Newton & Jeffrey, 1977) the -C(OH)COO-group is not planar (Table 4).…”

“…modification of potassium D-gluconate monohydrate (Panagiotopoulos, Jeffrey, La Placa& Hamilton, 1974) and in one of two different gluconate ions in manganese(II) o-gluconate dihydrate (Lis, 1979), by rotating 125 o about C(2)-C(3) (see Fig. 1 and Table 4).…”

Molecular conformation and electronic structure. VII. The structure of the isomorphic system p-chloro-N-(p-methylbenzylidene)aniline and p-methyl-N-(p-chlorobenzylidene)aniline

“…In each of these two polymorphic systems significantly different conformations are found in the different crystal structures, a phenomenon known as conformational polymorphism (Corradini, 1973;Panagiotopoulos, Jeffrey, La Placa & Hamilton, 1974). These findings led to quantitative studies of the influence of crystal forces on molecular conformation (Bernstein & Hagler, 1978;Bar & Bernstein, 1982b).…”

Crystallographic studies of carbohydrates

“…In one chain, the bonds are shorter than average [H-.-O = 1.691 (8), 1-723 (8), 1.729 (8) A], while in the other chain they are longer than average [H.-.O= 1.914 (9), 2-018 (9), 2-218 (8)A]. The two forms of potassium D-gluconate monohydrate studied by neutron diffraction (Panagiotopoulos, Jeffrey, LaPlaca & Hamilton, 1974) illustrate two types of hydrogenbond cooperativity. In the A form, the gluconate ion has the straight-chain conformation stabilized by an intramolecular O(4)H...O(2) hydrogen bond.…”

“…The D-gluconate ion in the crystal structure of potassium D-gluconate has a straight-chain conformation in one form and a bent-chain conformation in a second form. These structures were studied by neutron diffraction (Panagiotopoulos, Jeffrey, LaPlaca & Hamilton, 1974) and provide an interesting example of alternate modes of hydrogen bonding, which is discussed below. …”