Phosphate binding with a thiophene-based azamacrocycle in water
Musabbir A Saeed1, Avijit Pramanik, Md Alamgir Hossain
1Department of Chemistry and Biochemistry, Jackson State University, Jackson, MS 39217.
Inorganic Chemistry Communications
|July 23, 2013
Summary
This study shows a thiophene-based macrocycle can encapsulate dihydrogen phosphate dimers. The host-guest complexation was confirmed using NMR titrations and mass spectrometry.
Area of Science:
- Supramolecular chemistry
- Chemical crystallography
- Analytical chemistry
Background:
- Phosphate recognition and sensing are crucial in biological and environmental systems.
- Macrocyclic compounds offer tailored cavities for selective guest binding.
- Understanding host-guest interactions is key to designing new functional materials.
Purpose of the Study:
- To investigate the complexation of dihydrogen phosphate by a thiophene-based macrocycle.
- To characterize the structural and binding properties of the host-guest complex.
- To explore the potential of macrocycles for phosphate sensing applications.
Main Methods:
- Single-crystal X-ray diffraction for structural characterization.
- Proton Nuclear Magnetic Resonance (1H NMR) titrations for binding studies.
- Electrospray Ionization Mass Spectrometry (ESI-MS) for gas-phase complex confirmation.
Main Results:
- Structural analysis revealed encapsulation of dihydrogen phosphate dimers within the macrocycle via hydrogen bonds (NH···O and CH···O).
- The crystal lattice showed linear hydrogen bonding between dimers, forming a tetramer.
- 1H NMR titrations indicated a 1:1 host-guest complex with an association constant of 120 M-1 in D2O at pH 5.5.
- ESI-MS confirmed the host-guest complexation in the gas phase.
Conclusions:
- The thiophene-based macrocycle effectively binds dihydrogen phosphate anions.
- Hydrogen bonding plays a critical role in the encapsulation and stabilization of the phosphate complex.
- The study demonstrates the potential of this macrocycle for selective phosphate recognition.
Related Concept Videos
01:21The Phosphorus Cycle
Unlike carbon, water, and nitrogen, phosphorus is not present in the atmosphere as a gas. Instead, most phosphorus in the ecosystem exists as compounds, such as phosphate ions (PO43-), found in soil, water, sediment and rocks. Phosphorus is often a limiting nutrient (i.e., in short supply). Consequently, phosphorus is added to most agricultural fertilizers, which can cause environmental problems related to runoff in aquatic ecosystems.
01:11Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.