Abstract
Crystal structures of Schiff bases containing pyridoxal (PL), N-(pyridoxylidene)-tolylamine, C15H16N2O 2 (I), N-(pyridoxylidene)-methylamine, C9H 12N2O2 (III), and their 1:1 adduct with 2-nitrobenzoic acid, (I)+ C7H4NO (II), and 4-nitrobenzoic acid, (III)+ C7H4NO (IV), serve as models for the coenzyme pyridoxal-5′-phosphate (PLP) in its PLP-dependent enzymes. These models allow the study of the intramolecular OHN hydrogen bond of PL/PLP Schiff bases and the H-acceptor properties of their pyridine rings. The free base (I) forms hydrogen-bonded chains involving the hydroxyl side groups and the rings of adjacent molecules, whereas (III) forms related hydrogen-bonded cyclic dimers. The adducts (II)/(IV) consist of 1:1 hydrogen-bonded complexes, exhibiting strong intermolecular bonds between the carboxylic groups of the acids and the pyridine rings of (I)/(III). In conclusion, the proton in the intramolecular O - H⋯N hydrogen bond of (I)/(III) is located close to oxygen (enolamine form). The added acids protonate the pyridine ring in (II)/(IV), but only in the latter case does this protonation lead to a shift of the intramolecular proton towards the nitrogen (ketoimine form). All crystallographic structures were observed in the open form. In contrast, the formation of the pyridinium salt by dissolving (IV) leads to the cyclic aminal form.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 480-487 |
| Number of pages | 8 |
| Journal | Acta Crystallographica Section B: Structural Science |
| Volume | 62 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jun 2006 |
Fingerprint
ASJC Scopus subject areas
- Condensed Matter Physics
- Structural Biology
Cite this
X-ray crystallographic structures of enamine and amine Schiff bases of pyridoxal and its 1 : 1 hydrogen-bonded complexes with benzoic acid derivatives: Evidence for coupled inter- and intramolecular proton transfer. / Sharif, Shasad; Powell, Douglas R.; Schagen, David; Steiner, Thomas; Toney, Michael D.; Fogle, Emily; Limbach, Hans Heinrich.
In: Acta Crystallographica Section B: Structural Science, Vol. 62, No. 3, 06.2006, p. 480-487.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - X-ray crystallographic structures of enamine and amine Schiff bases of pyridoxal and its 1
T2 - 1 hydrogen-bonded complexes with benzoic acid derivatives: Evidence for coupled inter- and intramolecular proton transfer
AU - Sharif, Shasad
AU - Powell, Douglas R.
AU - Schagen, David
AU - Steiner, Thomas
AU - Toney, Michael D.
AU - Fogle, Emily
AU - Limbach, Hans Heinrich
PY - 2006/6
Y1 - 2006/6
N2 - Crystal structures of Schiff bases containing pyridoxal (PL), N-(pyridoxylidene)-tolylamine, C15H16N2O 2 (I), N-(pyridoxylidene)-methylamine, C9H 12N2O2 (III), and their 1:1 adduct with 2-nitrobenzoic acid, (I)+ C7H4NO (II), and 4-nitrobenzoic acid, (III)+ C7H4NO (IV), serve as models for the coenzyme pyridoxal-5′-phosphate (PLP) in its PLP-dependent enzymes. These models allow the study of the intramolecular OHN hydrogen bond of PL/PLP Schiff bases and the H-acceptor properties of their pyridine rings. The free base (I) forms hydrogen-bonded chains involving the hydroxyl side groups and the rings of adjacent molecules, whereas (III) forms related hydrogen-bonded cyclic dimers. The adducts (II)/(IV) consist of 1:1 hydrogen-bonded complexes, exhibiting strong intermolecular bonds between the carboxylic groups of the acids and the pyridine rings of (I)/(III). In conclusion, the proton in the intramolecular O - H⋯N hydrogen bond of (I)/(III) is located close to oxygen (enolamine form). The added acids protonate the pyridine ring in (II)/(IV), but only in the latter case does this protonation lead to a shift of the intramolecular proton towards the nitrogen (ketoimine form). All crystallographic structures were observed in the open form. In contrast, the formation of the pyridinium salt by dissolving (IV) leads to the cyclic aminal form.
AB - Crystal structures of Schiff bases containing pyridoxal (PL), N-(pyridoxylidene)-tolylamine, C15H16N2O 2 (I), N-(pyridoxylidene)-methylamine, C9H 12N2O2 (III), and their 1:1 adduct with 2-nitrobenzoic acid, (I)+ C7H4NO (II), and 4-nitrobenzoic acid, (III)+ C7H4NO (IV), serve as models for the coenzyme pyridoxal-5′-phosphate (PLP) in its PLP-dependent enzymes. These models allow the study of the intramolecular OHN hydrogen bond of PL/PLP Schiff bases and the H-acceptor properties of their pyridine rings. The free base (I) forms hydrogen-bonded chains involving the hydroxyl side groups and the rings of adjacent molecules, whereas (III) forms related hydrogen-bonded cyclic dimers. The adducts (II)/(IV) consist of 1:1 hydrogen-bonded complexes, exhibiting strong intermolecular bonds between the carboxylic groups of the acids and the pyridine rings of (I)/(III). In conclusion, the proton in the intramolecular O - H⋯N hydrogen bond of (I)/(III) is located close to oxygen (enolamine form). The added acids protonate the pyridine ring in (II)/(IV), but only in the latter case does this protonation lead to a shift of the intramolecular proton towards the nitrogen (ketoimine form). All crystallographic structures were observed in the open form. In contrast, the formation of the pyridinium salt by dissolving (IV) leads to the cyclic aminal form.
UR - http://www.scopus.com/inward/record.url?scp=33744731066&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33744731066&partnerID=8YFLogxK
U2 - 10.1107/S0108768105040590
DO - 10.1107/S0108768105040590
M3 - Article
C2 - 16710068
AN - SCOPUS:33744731066
VL - 62
SP - 480
EP - 487
JO - Acta Crystallographica Section B: Structural Science
JF - Acta Crystallographica Section B: Structural Science
SN - 0108-7681
IS - 3
ER -