Origins of optical absorption characteristics of Cu<sup>2+</sup> complexes in aqueous solutions

S. Roger Qiu, Brandon C. Wood, Paul R. Ehrmann, Stavros G. Demos, Philip E. Miller, Kathleen I. Schaffers, Tayyab I. Suratwala, Richard K. Brow

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Many transition metal complexes exhibit infrared or visible optical absorption arising from d-d transitions that are the key to functionality in technological applications and biological processes. The observed spectral characteristics of the absorption spectra depend on several underlying physical parameters whose relative contributions are still not fully understood. Although conventional arguments based on ligand-field theory can be invoked to rationalize the peak absorption energy, they cannot describe the detailed features of the observed spectral profile such as the spectral width and shape, or unexpected correlations between the oscillator strength and absorption peak position. Here, we combine experimental observations with first-principles simulations to investigate origins of the absorption spectral profile in model systems of aqueous Cu<sup>2+</sup> ions with Cl<sup>-</sup>, Br<sup>-</sup>, NO<inf>2</inf><sup>-</sup> and CH<inf>3</inf>CO<inf>2</inf><sup>-</sup> ligands. The ligand identity and concentration, fine structure in the electronic d-orbitals of Cu<sup>2+</sup>, complex geometry, and solvation environment are all found to play key roles in determining the spectral profile. Moreover, similar physiochemical origins of these factors lead to interesting and unexpected correlations in spectral features. The results provide important insights into the underlying mechanisms of the observed spectral features and offer a framework for advancing the ability of theoretical models to predict and interpret the behavior of such systems.

Original languageEnglish (US)
Pages (from-to)18913-18923
Number of pages11
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number29
DOIs
StatePublished - Aug 7 2015
Externally publishedYes

Fingerprint

Light absorption
optical absorption
Ligands
aqueous solutions
ligands
profiles
absorption spectra
Coordination Complexes
Solvation
energy absorption
Electron transitions
oscillator strengths
Transition metals
solvation
Absorption spectra
fine structure
transition metals
Ions
Infrared radiation
orbitals

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Physics and Astronomy(all)

Cite this

Qiu, S. R., Wood, B. C., Ehrmann, P. R., Demos, S. G., Miller, P. E., Schaffers, K. I., ... Brow, R. K. (2015). Origins of optical absorption characteristics of Cu<sup>2+</sup> complexes in aqueous solutions. Physical Chemistry Chemical Physics, 17(29), 18913-18923. https://doi.org/10.1039/c5cp01688f

Origins of optical absorption characteristics of Cu<sup>2+</sup> complexes in aqueous solutions. / Qiu, S. Roger; Wood, Brandon C.; Ehrmann, Paul R.; Demos, Stavros G.; Miller, Philip E.; Schaffers, Kathleen I.; Suratwala, Tayyab I.; Brow, Richard K.

In: Physical Chemistry Chemical Physics, Vol. 17, No. 29, 07.08.2015, p. 18913-18923.

Research output: Contribution to journalArticle

Qiu, SR, Wood, BC, Ehrmann, PR, Demos, SG, Miller, PE, Schaffers, KI, Suratwala, TI & Brow, RK 2015, 'Origins of optical absorption characteristics of Cu<sup>2+</sup> complexes in aqueous solutions', Physical Chemistry Chemical Physics, vol. 17, no. 29, pp. 18913-18923. https://doi.org/10.1039/c5cp01688f
Qiu, S. Roger ; Wood, Brandon C. ; Ehrmann, Paul R. ; Demos, Stavros G. ; Miller, Philip E. ; Schaffers, Kathleen I. ; Suratwala, Tayyab I. ; Brow, Richard K. / Origins of optical absorption characteristics of Cu<sup>2+</sup> complexes in aqueous solutions. In: Physical Chemistry Chemical Physics. 2015 ; Vol. 17, No. 29. pp. 18913-18923.
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