title: Recognition of silver nanoparticles surface-adsorbed citrate anions by macrocyclic polyammonium cations: a spectrophotometric approach to study aggregation kinetics and evaluation of association constant.
abstract: In this report, we have studied the recognition of citrate anions adsorbed on the surface of silver nanoparticles (cit-Ag-NPs), by macrocyclic polyammonium cations (MCPACs): Me6 [14]ane-N4 H8 (4+) (Tet-A/Tet-B cations) and [32]ane-N8 H16 (8+) , which are well reputed anion recognizers and are treated as to mimic of biological polyamines. The study was monitored on ultraviolet-visible spectroscopy by performing a titration of the aqueous dispersion of the cit-Ag-NPs by the aqueous solution of MCPACs. The ultraviolet-visible time-scan plots over the reduction of the absorption band of surface plasmon resonance of cit-Ag-NPs at 390 nm are well fitted with fourth-order polynomial equation and are employed to determine the initial aggregation rate constants. It has been stated that the aggregation is the result in electrostatic attraction followed by H-bond formation between the surface-adsorbed citrate anions and added MCPACs. The atomic force microscopy results have evidenced aggregation of cit-Ag-NPs in presence of MCPACs. The evaluated H-bonded association constant (Kasso ) using Benesi-Hildebrand method reveals that [32]ane-N8 H16 (8+) cations form stronger association complex, as expected, with the citrate anions than the Me6 [14]ane-N4 H8 (4+) cations. The study would thus provide the insight of molecular interactions involved in nanoparticle surface-adsorbed anions with biological polyamines. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Department of Chemistry, National Institute of Technology, Agartala, Tripura, 799046, India.
authors.forename: Rupasree
authors.initials: R
authors.lastname: Choudhury
authors.affiliation: Department of Chemistry, National Institute of Technology, Agartala, Tripura, 799046, India.
authors.forename: Atanu
authors.initials: A
authors.lastname: Purkayastha
authors.affiliation: Department of Chemistry, National Institute of Technology, Agartala, Tripura, 799046, India.
authors.forename: Diptanu
authors.initials: D
authors.lastname: Debnath
authors.affiliation: Department of Chemistry, National Institute of Technology, Agartala, Tripura, 799046, India.
authors.forename: Tarun Kumar
authors.initials: TK
authors.lastname: Misra
mesh_terms: D064751:Ammonium Compounds / Q000737:chemistry*; D000838:Anions / Q000737:chemistry*; D002412:Cations / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry*; D006860:Hydrogen Bonding; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D011073:Polyamines / Q000737:chemistry; D012834:Silver / Q000737:chemistry
chemical_list: D064751:Ammonium Compounds; D000838:Anions; D002412:Cations; D011073:Polyamines; D019343:Citric Acid; D012834:Silver
keywords: aggregation kinetics; association constant; citrate anions; macrocyclic polyammoniun cations; silver nanoparticles