Normal-mode characteristics of chlorophyll models. Vibrational analysis of metallooctaethylchlorins and their selectively deuterated analogues

Journal Article · Tue Dec 18 23:00:00 EST 1990 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00182a008· OSTI ID:5637586

Fonda, H N; Oertling, W A; Salehi, A; Chang, C K; Babcock, G T ^[1]

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1. Michigan State Univ., East Lansing (United States)

The resonance Raman (RR) and infrared (IR) spectra of the Zn, Cu, and Ni complexes of trans-octaethylchlorin (OEC) reveal significant differences in the vibrational-mode properties of metallochlorins and metalloporphyrins. Modes with a contribution from the C{sub a}C{sub m} stretching coordinate are distinguished by their sensitivity to metal substitution and to selective d{sub 2} and d{sub 4} methine deuteration. Comparison of the resonance Raman spectrum of CuOEC with that of CuECI (ECI = etiochlorin I) identifies those modes with a contribution from C{sub b}C{sub b} and C{sub b}C{sub s} stretching and C{sub b}C{sub s} bending coordinates. The results obtained show that there is substantial mixing of C{sub a}C{sub m} and C{sub b}C{sub b} stretching character in the high-frequency modes of MOEC. The suggestion that the symmetry reduction that occurs in metallochlorins relative to metalloporphyrins produces vibrational-mode localization to specific hemispheres or quadrants of the macrocycle has been tested and confirmed by specific d{sub 2} deuteration at the methine carbons. Resonance Raman spectra of CuOEP-d{sub 2} (OEP = octaethylporphyrin) and CuOEP-d{sub 4} establish that, for a delocalized mode, methine d{sub 2} deuteration can be expected to produce half the d{sub 4} shift. For CuOEC, selective deuteration at the {alpha}{beta} and {gamma},{delta} methine positions causes different patterns of frequency shifts that indicate the extent of mode localization.

• OSTI ID: 5637586
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 112:26; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical & Spectral Procedures
400500 -- Photochemistry
ABSORPTION SPECTROSCOPY
CARBOXYLIC ACIDS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHLORINS
CHLOROPHYLL
COMPLEXES
COPPER COMPLEXES
DATA
DEUTERATION
EXPERIMENTAL DATA
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
INFRARED SPECTRA
LASER SPECTROSCOPY
NICKEL COMPLEXES
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RAMAN SPECTRA
RAMAN SPECTROSCOPY
SPECTRA
SPECTROSCOPY
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
ZINC COMPLEXES