The absolute configuration of α(+)-tris-<scp>L</scp>-alaninatocobalt(<scp>III</scp>)

Drew, Michael G. B.; Dunlop, J. H.; Gillard, R. D.; Rogers, Dan

doi:10.1039/c19660000042

Cited by 10 publications

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“…A difference in the solubilities of these isomers has become of interest. In general, the mer -isomers are more soluble than the fac -isomers and the ( − )-isomers of tris( L -amino acidato)cobalt( ) ([Co( L -aa) 3 ]) are more soluble than the corresponding ( + )-isomers. Denning and Piper 2 tried to explain the difference in the solubilities of the ( + )-and ( − )-isomers of [Co( L -ala) 3 ] based on a distinction in the position of the sidechain methyl groups of alanine.…”

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“…In general, the mer -isomers are more soluble than the fac -isomers and the ( − )-isomers of tris( L -amino acidato)cobalt( ) ([Co( L -aa) 3 ]) are more soluble than the corresponding ( + )-isomers. Denning and Piper 2 tried to explain the difference in the solubilities of the ( + )-and ( − )-isomers of [Co( L -ala) 3 ] based on a distinction in the position of the sidechain methyl groups of alanine. However, Heark et al 4 have pointed out that the solubility differences of various isomers of [Co( L -ala) 3 ] are not closely related to the positions of the methyl groups.…”

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confidence: 99%

“…However, Heark et al 4 have pointed out that the solubility differences of various isomers of [Co( L -ala) 3 ] are not closely related to the positions of the methyl groups. The extreme low solubility of fac -( + )-[Co( Lala) 3 ] has been attributed to molecular association through intermolecular hydrogen bonding in its solid state. 1,5 However, fac -( + )-tris( L -threoninato)cobalt( ) ( fac -( +)-[Co(L-thr) 3 ]) has been reported to be considerably soluble.…”

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confidence: 99%

“…From X-ray diffraction studies, the absolute configurations of mer -( + )-tris( L -alaninato)cobalt( ) ( mer -( + )-[Co( L -ala) 3 ]) 3 and mer -( − )-[Co( L -ala) 3 ] 4 have been assigned to the Λ -and ∆ -isomers, respectively. In this paper, the Λ -and ∆ -isomers are expressed as the ( + )-and ( − )-isomers, respectively.…”

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confidence: 99%

“…Denning and Piper 2 tried to explain the difference in the solubilities of the ( + )-and ( − )-isomers of [Co( L -ala) 3 ] based on a distinction in the position of the sidechain methyl groups of alanine. However, Heark et al 4 have pointed out that the solubility differences of various isomers of [Co( L -ala) 3 ] are not closely related to the positions of the methyl groups. The extreme low solubility of fac -( + )-[Co( Lala) 3 ] has been attributed to molecular association through intermolecular hydrogen bonding in its solid state.…”

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confidence: 99%

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Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)

Yoshimura¹

2002

Bulletin of the Chemical Society of Japan

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The solubilities of soluble mer-(-)-isomers of various tris(amino acidato)cobalt(III) ([Co(aa)3]) in water were determined over the temperature range 5 to 50 °C. From these data the standard free energy (ΔdisG°), enthalpy (ΔdisH°), and entropy of dissolution (ΔdisS°) at 25 °C were estimated and compared with the values reported for mer-(+)-, fac-(-)-, and fac-(+)-isomers of [Co(aa)3]. The solubilities of these isomers increase in the order fac-(+)- < fac-(-)- < mer-(+)- < mer-(-)-isomers for [Co(aa)3] synthesized from amino acids with longer side chains than 2-aminobutyric acid. On the other hand, the increasing sequence of the solubilities for tris(L-alaninato)cobalt(III) ([Co(L-ala)3]) and tris(L-serinato)cobalt(III) ([Co(L-ser)3]) is fac-(+)- < mer-(+)- < fac-(-)- < mer-(-)-isomers. The solubility differences between the mer- and fac-isomers and between the (-)- and (+)-isomers are discussed based on the differences of ΔdisH° and TΔdisS° among these isomers. Furthermore, the influence of introducing hydroxyl and methyl groups into the side chains of the amino acids on the dissolution behavior of [Co(aa)3] is discussed.

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Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)

Yoshimura¹

2002

Bulletin of the Chemical Society of Japan

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Stereochemical Aspects of Vibrational Optical Activity

Freedman¹,

Nafie²

1987

Topics in Stereochemistry

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Compounds of Amino Acids as Anions

Fleck

Petrosyan

2014

Salts of Amino Acids

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This chapter deals with salts formed from metal cations and amino acid anions. All amino acids can act as monovalent anion; the acidic members glutamic acid and aspartic acid as well as cysteine and tyrosine can form both monovalent and divalent anions. Due to the large number of available cations, a multitude of combinations is possible and in fact found (for the standard twenty amino acids, over 150 crystal structures are published, and many more species have been characterized by other methods). Different hydration states (as reported for the pristine amino acid crystals) occur as well, and the existence of polymorphs is also documented for some cases. The formation of metal-amino acid complexes has been studied in several works (both for a given amino acid and a given cation), and the flexibility of amino acid molecules as ligands allows coordination of cations with different chemical properties (such as charge or ionic radius). Several coordination modes are found for amino acids -the molecules can act as monodentate, bidentate, tridentate, and bridging ligands. The connectivity of the coordination polyhedra of the metal cations is considered -isolated units are frequent, but chains and layers occur as well. Moreover, these units can connect via amino acid molecules to form higher-dimensional structures. Hydrogen bonds (also involving water molecules, both in coordination or in the interstices as crystal water) further stabilize the units, forming relatively stable phases. The frequency of salts varies among the different amino acids, and most examples are reported for glycinate salts, whereas crystals of cations and basic and weakly soluble amino acids are difficult to obtain (e.g., arginate and lysinate salts have not been reported in crystalline state). Finally, the aspect of symmetry is considered (the chirality of most amino acids playing a crucial role), and, consequently, the properties of these salts have impact on applications in the fields of physics, biology, and medicine.

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The absolute configuration of α(+)-tris-L-alaninatocobalt(III)

Cited by 10 publications

References 0 publications

Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)

Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)

Stereochemical Aspects of Vibrational Optical Activity

Compounds of Amino Acids as Anions

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