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  • Simultaneous resonance Raman optical activity involving two electronic states.

Simultaneous resonance Raman optical activity involving two electronic states.

The journal of physical chemistry. A (2012-06-06)
Christian Merten, Honggang Li, Laurence A Nafie
ABSTRACT

In the present work, the first observation of strong resonance Raman optical activity (RROA) involving more that one resonant electronic state is reported. The chiral transition metal complex bis-(trifluoroacetylcamphorato) copper(II), abbreviated Cu(tfc)(2), exhibits both resonance Raman (RR) and RROA spectra with laser excitation at 532 nm. Vibrational assignments for this complex were carried out by comparing the non-RR spectra of Cu(tfc)(2) excited at 1024 nm to density functional theory (DFT) calculations. The theory of the single-electronic-state (SES) RROA is extended to the next simplest level of theory involving two resonant electronic states (TES) without interstate vibronic coupling as an aide to the interpretation of the observed TES-RROA spectra. Based on measured UV-vis electronic absorbance spectra and corresponding TD-DFT calculations, the most likely two states associated with the RROA spectra are identified.

MATERIALS
Product Number
Brand
Product Description

Camphor (dl), primary reference standard
Sigma-Aldrich
(±)-Camphor, meets analytical specification of Ph. Eur., BP, racemic, ≥95% (GC)
Supelco
(−)-Camphor, analytical standard
Sigma-Aldrich
(1R)-(+)-Camphor, 98%
Sigma-Aldrich
(±)-Camphor, ≥95.5%
Sigma-Aldrich
Camphor, 96%
Sigma-Aldrich
(±)-Camphor, purum, synthetic, ≥95.0% (GC)
Camphor (racemic), European Pharmacopoeia (EP) Reference Standard
Supelco
D-Camphor, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
D-Camphor, ≥97%, FG
Sigma-Aldrich
(1S)-(−)-Camphor, 95%