Metalloporphyrins have been widely utilized as building blocks for molecular self-assembly in organic solvents, but their application in water is less common due to competition from water molecules for the metal center. However, Co(III) metalloporphyrins are notable for their strong binding to two aromatic amine ligands in aqueous buffers. In this study, we present a comprehensive investigation of the binding behavior of Co(III) tetraphenyl sulfonic acid porphyrin with selected aromatic and aliphatic amines in aqueous solution. Our findings reveal that the ligand affinity is influenced by the p values of both the ligand and the porphyrin, as well as the hybridization state of the nitrogen atom, with binding to sp-hybridized nitrogen being significantly weaker than to sp-hybridized nitrogen. DFT calculations further suggest that the variations in binding affinities are due to differences in the electrostatic potential at the nitrogen atoms, with aromatic ligands generally exhibiting stronger Co-N coordination due to greater electrostatic attraction. Moreover, our study and the binding model we developed demonstrate that changes in pH affect the affinity for each ligand to varying degrees, sometimes resulting in an allosteric cooperative effect. This effect is linked to electronic changes introduced by the binding of the first ligand. Our model provides a predictive tool for understanding the assembly behavior of these porphyrins in aqueous buffers, with potential applications in developing more efficient catalysts and in the creation of smart materials for fields ranging from catalysis to nanomedicine and optoelectronics.
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http://dx.doi.org/10.1021/acs.inorgchem.4c04183 | DOI Listing |
Inorg Chem
December 2024
Departament de Química, Universitat de les Illes Balears, Ctra Valldemossa, Km 7.5., 07122 Palma de Mallorca, Spain.
Metalloporphyrins have been widely utilized as building blocks for molecular self-assembly in organic solvents, but their application in water is less common due to competition from water molecules for the metal center. However, Co(III) metalloporphyrins are notable for their strong binding to two aromatic amine ligands in aqueous buffers. In this study, we present a comprehensive investigation of the binding behavior of Co(III) tetraphenyl sulfonic acid porphyrin with selected aromatic and aliphatic amines in aqueous solution.
View Article and Find Full Text PDFJ Org Chem
December 2024
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States.
Aqueous solubilization of porphyrins, often accomplished with appended polar aryl groups, can also be achieved with symmetrically branched alkyl (i.e., swallowtail) groups terminated with polar moieties.
View Article and Find Full Text PDFJ Fluoresc
December 2024
National Centre of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, 76080, Pakistan.
This paper describes the synthesis of CoFe₂O₄ nanoparticles via a simple ultrasonic-assisted co-precipitation method and their functionalization with thiol groups using (3-Mercaptopropyl)trimethoxysilane (MPTS) as the functionalizing agent. The use of ultrasonic energy not only serves as a green energy source but also reduces the reaction time fivefold compared to conventional methods. The synthesized CoFe₂O₄ nanoparticles were characterized for their surface and internal properties using instrumental techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vibrating Sample Magnetometer (VSM).
View Article and Find Full Text PDFDrug Dev Ind Pharm
December 2024
Quotient Sciences, Nottingham, UK.
Objective: This pilot study aimed to develop a liquid formulation of tenapanor and evaluate taste and palatability with different sweetener and flavor combinations.Significance: Tenapanor is a first-in-class, minimally absorbed, small molecule inhibitor of intestinal sodium/hydrogen exchanger 3, indicated (as tablets) to treat adults with constipation-predominant irritable bowel syndrome. It is also approved as add-on therapy to reduce serum phosphorus in adults with chronic kidney disease on dialysis who are intolerant of, or unacceptably responsive to, any dose of phosphate binder therapy.
View Article and Find Full Text PDFJ Colloid Interface Sci
December 2024
Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2100, Denmark; Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Parkville 3052, VIC Australia. Electronic address:
Hypothesis: Low-frequency Raman (LFR) spectroscopy is proposed as a novel non-destructive methodology to probe pH-related phase transitions in self-assembled lipid particles. In this case, dispersed lipid mesophases were composed of ionisable oleic acid (OA) or nicergoline (NG) in monoolein (MO). The sensitivity of LFR spectroscopy to low-energy intermolecular vibrations was hypothesised to be due to structural transformation in ionisable dispersed mesophases upon changes in pH.
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