Solution and structural binding studies of phosphate with thiophene-based azamacrocycles

Syed A Haque; Rainier S Berkley; Frank R Fronczek; Md Alamgir Hossain

doi:10.1016/j.inoche.2016.05.013

Solution and structural binding studies of phosphate with thiophene-based azamacrocycles

Inorg Chem Commun. 2016 Aug:70:121-124. doi: 10.1016/j.inoche.2016.05.013. Epub 2016 May 27.

Authors

Syed A Haque¹, Rainier S Berkley¹, Frank R Fronczek², Md Alamgir Hossain¹

Affiliations

¹ Department of Chemistry and Biochemistry, Jackson State University, Jackson, MS 39217, USA.
² Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803, USA.

Abstract

Two thiophene-based monocyclic receptors L1 and L2 have been studied for phosphate binding in solutions (D₂O and DMSO-d₆ ) by ¹H NMR and ³¹P NMR titrations, and in the solid state by single crystal X-ray analysis. Results from ¹H NMR titrations suggest that the ligands bind phosphate anions in a 1:2 binding mode in DMSO-d₆ , with the binding constants of 5.25 and 4.20 (in log K), respectively. The binding of phosphate to L1 and L2 was further supported by ³¹P NMR in D₂O at pH = 5.2. The crystal structure of the phosphate complex of L1 reveals unambiguous proof for the formation of a ditopic complex via multiple hydrogen bonds from NH···O and CH···O interactions.

Keywords: Anion binding; Azamacrocycle; Ditopic complex; Phosphate complex.

Grants and funding

G12 MD007581/MD/NIMHD NIH HHS/United States