Spectroscopy of polyenes. 6. Absorption and emission spectral properties of linear polyenals of the series CH/sub 3/-(CH=CH)/sub n/-CHO

Journal Article · Thu Mar 18 00:00:00 EST 1982 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100395a017· OSTI ID:5611476

Das, P K ^[1]; Becker, R S

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1. Univ. of Notre Dame, IN

The results of a detailed study are presented concerning the absorption and emission spectral properties of four homologous polyenals of the series, CH/sub 3/-(CH=CH)/sub n/-CHO, n = 2-5, under various conditions of solvent and temperature. A total of four different band systems have been recognized in the well-resolved absorption spectra. These have been assigned as arising from singlet ..pi..* reverse arrow n (very weak), /sup 1/B/sub u/* reverse arrow /sup 1/A/sub g/ (very strong), /sup 1/A/sub g/*/sup +/ reverse arrow /sup 1/A/sub g/ (cis peak, moderately weak), and /sup 1/A/sub g/*/sup -/ reverse arrow /sup 1/A/sub g/ (weak) transitions. Except for the /sup 1/A/sub g/*/sup +/ state which is always located at a relatively high energy, the relative location of the remaining three states, viz., /sup 1/B/sub u/*, /sup 1/A/sub g/*/sup -/, and /sup 1/(n,..pi..*), is seen to be a sensitive function of polyene chain length and appears to be the most important factor in determining the radiative behavior of the polyenals. Thus, the C/sub 6/ and C/sub 8/ aldehydes (n = 2 and 3), with a /sup 1/(n,..pi..*) state seen as the lowest singlet state in absorption, do not fluoresce under any condition of solvents (polar and nonpolar) and temperature (296-77 K). The C/sub 12/ aldehyde (n = 5) has the dipole-forbidden /sup 1/A/sub g/*/sup -/ state as the lowest singlet state and exhibits fluorescence (at 77 K) that is moderately strong. In the case of the intermediate polyenal, C/sub 10/ aldehyde (n = 4), the three low-lying states, viz., /sup 1/(n,..pi..*), /sup 1/B/sub u/*, and /sup 1/A/sub g/*/sup -/, appear to be nearly degenerate based on their locations in the absorption spectra.

• OSTI ID: 5611476
• Journal Information: J. Phys. Chem.; (United States), Vol. 86:6
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
POLYENES
ABSORPTION SPECTRA
EMISSION SPECTRA
EXPERIMENTAL DATA
FLUORESCENCE
HIGH TEMPERATURE
MEDIUM TEMPERATURE
ORGANIC SOLVENTS
SPECTROSCOPY
TEMPERATURE EFFECTS
DATA
HYDROCARBONS
INFORMATION
LUMINESCENCE
NUMERICAL DATA
ORGANIC COMPOUNDS
SOLVENTS
SPECTRA
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)