TY - JOUR

T1 - The effect of amino acid backbone length on molecular packing

T2 - Crystalline tartrates of glycine, β-alanine, γ-aminobutyric acid (GABA) and dl-α-aminobutyric acid (AABA).

AU - Losev, Evgeniy

AU - Boldyreva, Elena

PY - 2018/2/1

Y1 - 2018/2/1

N2 - We report a novel 1:1 cocrystal of β-alanine with dl-tartaric acid, C3H7NO2·C4H6O6, (II), and three new molecular salts of dl-tartaric acid with β-alanine {3-azaniumylpropanoic acid-3-azaniumylpropanoate dl-tartaric acid-dl-tartrate, [H(C3H7NO2)2]+·[H(C4H5O6)2]-, (III)}, γ-aminobutyric acid [3-carboxypropanaminium dl-tartrate, C4H10NO2 +·C4H5O6 -, (IV)] and dl-α-aminobutyric acid {dl-2-azaniumylbutanoic acid-dl-2-azaniumylbutanoate dl-tartaric acid-dl-tartrate, [H(C4H9NO2)2]+·[H(C4H5O6)2]-, (V)}. The crystal structures of binary crystals of dl-tartaric acid with glycine, (I), β-alanine, (II) and (III), GABA, (IV), and dl-AABA, (V), have similar molecular packing and crystallographic motifs. The shortest amino acid (i.e. glycine) forms a cocrystal, (I), with dl-tartaric acid, whereas the larger amino acids form molecular salts, viz. (IV) and (V). β-Alanine is the only amino acid capable of forming both a cocrystal [i.e. (II)] and a molecular salt [i.e. (III)] with dl-tartaric acid. The cocrystals of glycine and β-alanine with dl-tartaric acid, i.e. (I) and (II), respectively, contain chains of amino acid zwitterions, similar to the structure of pure glycine. In the structures of the molecular salts of amino acids, the amino acid cations form isolated dimers [of β-alanine in (III), GABA in (IV) and dl-AABA in (V)], which are linked by strong O-H.O hydrogen bonds. Moreover, the three crystal structures comprise different types of dimeric cations, i.e. (A.A)+ in (III) and (V), and A+.A+ in (IV). Molecular salts (IV) and (V) are the first examples of molecular salts of GABA and dl-AABA that contain dimers of amino acid cations. The geometry of each investigated amino acid (except dl-AABA) correlates with the melting point of its mixed crystal.The effect of amino acid backbone length on molecular packing has been studied using crystalline tartrates of glycine, β-alanine, γ-aminobutyric acid (GABA) and dl-α-aminobutyric acid (AABA) as examples.

AB - We report a novel 1:1 cocrystal of β-alanine with dl-tartaric acid, C3H7NO2·C4H6O6, (II), and three new molecular salts of dl-tartaric acid with β-alanine {3-azaniumylpropanoic acid-3-azaniumylpropanoate dl-tartaric acid-dl-tartrate, [H(C3H7NO2)2]+·[H(C4H5O6)2]-, (III)}, γ-aminobutyric acid [3-carboxypropanaminium dl-tartrate, C4H10NO2 +·C4H5O6 -, (IV)] and dl-α-aminobutyric acid {dl-2-azaniumylbutanoic acid-dl-2-azaniumylbutanoate dl-tartaric acid-dl-tartrate, [H(C4H9NO2)2]+·[H(C4H5O6)2]-, (V)}. The crystal structures of binary crystals of dl-tartaric acid with glycine, (I), β-alanine, (II) and (III), GABA, (IV), and dl-AABA, (V), have similar molecular packing and crystallographic motifs. The shortest amino acid (i.e. glycine) forms a cocrystal, (I), with dl-tartaric acid, whereas the larger amino acids form molecular salts, viz. (IV) and (V). β-Alanine is the only amino acid capable of forming both a cocrystal [i.e. (II)] and a molecular salt [i.e. (III)] with dl-tartaric acid. The cocrystals of glycine and β-alanine with dl-tartaric acid, i.e. (I) and (II), respectively, contain chains of amino acid zwitterions, similar to the structure of pure glycine. In the structures of the molecular salts of amino acids, the amino acid cations form isolated dimers [of β-alanine in (III), GABA in (IV) and dl-AABA in (V)], which are linked by strong O-H.O hydrogen bonds. Moreover, the three crystal structures comprise different types of dimeric cations, i.e. (A.A)+ in (III) and (V), and A+.A+ in (IV). Molecular salts (IV) and (V) are the first examples of molecular salts of GABA and dl-AABA that contain dimers of amino acid cations. The geometry of each investigated amino acid (except dl-AABA) correlates with the melting point of its mixed crystal.The effect of amino acid backbone length on molecular packing has been studied using crystalline tartrates of glycine, β-alanine, γ-aminobutyric acid (GABA) and dl-α-aminobutyric acid (AABA) as examples.

KW - crystal engineering

KW - crystal structure

KW - dimeric cation/anion

KW - glycine

KW - hydrogen bonds

KW - Molecular Salts

KW - α-aminobutyric acid

KW - β-alanine

KW - γ-aminobutyric acid

KW - BUTYRIC-ACID

KW - molecular salts

KW - gamma-aminobutyric acid

KW - COCRYSTAL

KW - POLYMORPHISM

KW - SALTS

KW - SUPRAMOLECULAR SYNTHONS

KW - PHASE

KW - beta-alanine

KW - alpha-aminobutyric acid

KW - STRUCTURE PREDICTION

KW - NORVALINE

KW - CARBOXYLIC-ACIDS

KW - MALEATE

KW - Amino Acids/chemistry

KW - Crystallography, X-Ray

KW - Molecular Structure

KW - Tartrates/chemistry

KW - Hydrogen Bonding

KW - Salts/chemistry

UR - http://www.scopus.com/inward/record.url?scp=85041468130&partnerID=8YFLogxK

U2 - 10.1107/S2053229617017909

DO - 10.1107/S2053229617017909

M3 - Article

C2 - 29400333

AN - SCOPUS:85041468130

VL - 74

SP - 177

EP - 185

JO - Acta Crystallographica Section C: Structural Chemistry

JF - Acta Crystallographica Section C: Structural Chemistry

SN - 2053-2296

IS - 2

ER -