In the title compound, C(4)H(8)N(2)O(3)·C(4)H(6)O(6), the amino acid mol-ecule exists as a zwitterion and the carb-oxy-lic acid in an un-ionized state. The tartaric acid mol-ecules are linked into layers parallel to the ab plane by O-H⋯O hydrogen bonds. The amino acid mol-ecules are also linked into layers parallel to the ab plane by N-H⋯O and C-H⋯O hydrogen bonds. The alternating tartaric acid...

The reaction of 4-amino-pyridine and oleum yielded the title hydrated zwitterion, C(5)H(6)N(2)O(3)S·H(2)O. There are two formula units in the asymmetric unit. The H and non-H atoms of both zwitterions lie on a mirror plane except for one sulfonate O atom. The water mol-ecules are also situated on a mirror plane. In the crystal, the zwitterions and water mol-ecules are linked by O-H⋯O and N-H⋯O ...

In the title structure, C(7)H(9)N(3)O(2)·H(2)O, there are two formula units in the asymmetric unit. The mol-ecule is a zwitterion, containing a quaternary N atom and a deprotonated carboxyl group, with C-O distances in the range 1.256 (2)-1.266 (3) Å. The two independent mol-ecules form a hydrogen-bonded R(2) (2)(16) dimer about an approximate inversion center via N-H⋯O hydrogen bonds, with N⋯O...

In Streptomyces hydrogenans, acidic amino acids are taken up either as anions by a specific transport system or as zwitterions via a nonspecific one. Variations in the zwitterion concentration caused by changes in pH influence the uptake and exchange diffusion by the nonspecific system. Differences in pH-optima for L-glutamate and L-aspartate transport are due to the different pK2-values of the...

The title Schiff base compound, C(15)H(15)NO(2), crystallized as the iminium-phenolate zwitterion. The H atom is localized on the imine N atom, forming a strong intra-molecular hydrogen bond with the phenolate O atom, and giving rise to an S(6) ring motif. The mol-ecule has an E conformation about the C=N bond. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, forming chains propag...

The vibrational frequencies for the fundamental modes and the energies of low lying states of alanine in neutral and its zwitterionic form in gas phase have been calculated at RMP2 ab-initio level. The results so obtained have been compared with earlier theoretical calculations and experimental observations of IR and RAMAN spectrum. In the present study, it has been observed that our results ar...

A modified CNDO/2 method was used to calculate the conformational energy surface of zwitterionic glycine in a simulated polarizable environment. While the calculated global minimum for the in vacuo glycine zwitterion corresponds to an eclipsed conformation, the allowance of even a small degree of environmental polarisability inverts the relative stabilities of the staggered and eclipsed forms. ...

The title Schiff base compound, C(18)H(13)NO(2), is a zwitterion, with the naphthol hy-droxy group deprotonated and the imine N atom protonated. It adopts an E configuration about the central C=N double bond. The dihedral angle between the naphthyl ring system and the benzene ring is 1.73 (11)°. An intra-molecular N-H⋯O hydrogen bond generates an S(6) ring motif. In the crystal, adjacent mol-ec...

The structure of 8-amino-2-naphthalene-sulfonic acid monohydrate (1,7-Cleve's acid hydrate), C(10)H(9)NO(3)S·H(2)O, shows the presence of a sulfonate-aminium group zwitterion, both groups and the water mol-ecule of solvation giving cyclic R(3) (3)(8) O-H⋯O and N-H⋯O inter-molecular hydrogen-bonding inter-actions, forming chains which extend down the a axis of the unit cell. Additional periphera...

The title compound, C(18)H(16)ClN(3)O(4)S, is a Schiff base ligand in which the H atom of the hydr-oxy group has moved to the N atom of the imine group, resulting in a zwitterion. The structure is stabilized by an intra-molecular (N-H⋯O) and five inter-molecular (C-H⋯O, C-H⋯N and N-H⋯O) hydrogen bonds. The mol-ecules are linked to each other by hydrogen bonds and form a three-dimensional polyme...