1 research outputs found
Probing the Formation, Structure, and Reactivity of Zn(II), Ag(I), and Fe(II) Complexes with 2,2′:6′,2″-Terpyridine on Ag Nanoparticles Surfaces by Time Evolution of SERS Spectra, Factor Analysis, and DFT Calculations
The
adsorption and surface reactivity of 2,2′:6′,2″-terpyridine
(tpy) and its metal (M = Zn<sup>2+</sup>, Fe<sup>2+</sup>, Ag<sup>+</sup>) complexes on Ag nanoparticle surfaces together with the
structure of the resulting M<sub>s</sub><sup>X+</sup>-tpy surface species and the mechanism of
their formation have been investigated. The process was elucidated
by time-dependent surface-enhanced Raman scattering (SERS) spectra,
their treatment by factor analysis (FA), density functional theory
(DFT) calculations of Raman spectra, and comparison of the SERS spectra
of the surface species (obtained by FA) with the Raman spectra of
their synthetic analogues (characterized by X-ray diffraction). SERS
spectral time evolution revealed surface-induced decomposition of
the [Zn(tpy)<sub>2</sub>]<sup>2+</sup> complex and formation of Zn<sub>s</sub><sup>2+</sup>-tpy and Ag<sub>s</sub><sup>+</sup>-tpy surface species,
accompanied by a ligand exchange of one tpy ligand for chloride anions
on the Zn<sup>2+</sup> center. The inhibition of Ag<sub>s</sub><sup>+</sup>-tpy surface species formation
was achieved by addition of Zn<sup>2+</sup> cations prior to the addition
of the [Zn(tpy)<sub>2</sub>]<sup>2+</sup> complex. The [Fe(tpy)<sub>2</sub>]<sup>2+</sup> complex exhibited no surface decomposition
and was identical to the Fe<sub>s</sub><sup>2+</sup>-tpy surface species. Additionally, generation
of M<sub>s</sub><sup>X+</sup>-tpy
species on the Ag nanoparticle surfaces by reaction of tpy and M<sup><i>x</i>+</sup> cations was monitored by SERS and evaluated
by FA. Determination of the Zn<sub>s</sub><sup>2+</sup>-tpy and Ag<sub>s</sub><sup>+</sup>-tpy structures was supported by DFT calculations
of the Raman spectra of Zn-tpy and Ag-tpy fragments