Excited-state absorption spectroscopy and state ordering in polyenes

Horwitz, J. S.; Goldbeck, Robert A.; Kliger, David S.

doi:10.1016/0009-2614(81)80098-x

Cited by 14 publications

(9 citation statements)

References 33 publications

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“…Nanosecond flash photolysis has shown that the intensity of the S n -S 1 excited-state absorption is very small at wavelengths longer than 460 nm. 23 These observations suggest that the transient absorption measured at longer wavelengths originates not from the S 1 state, but from the S 2 state. The fast-decay components at longer wavelengths reflect internal conversion from the S 2 to S 1 state.…”

Section: Internalmentioning

confidence: 93%

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S₂ to S₁ State and Relaxation Processes in the S₁ State

et al. 2001

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Femtosecond transient absorption spectroscopy was used to study the excited-state dynamics of the S 2 (1 1 B u ) state all-trans-1,3,5,7-octatetraene in solution. The sample was excited at 267 nm and probed at eleven different wavelengths from 340 to 540 nm. Combined with the picosecond fluorescence spectroscopy, this study allows direct observation of the initial excited-state dynamics of all-trans-1,3,5,7-octatetraene and the subsequent relaxation process to the ground state. Transient absorption signals decaying on time scales of about 0.4 ps were seen at wavelengths longer than 480 nm. These absorptions are assigned to an S n -S 2 transition, indicating that internal conversion from the S 2 to S 1 state takes place on a 400-fs time scale. The transient absorption signals observed at shorter wavelengths, which correspond to the S n -S 1 transition, decay on a picosecond to subnanosecond time scale. A weak fluorescence at about 300-350 nm, originating from the S 2 state, and a strong fluorescence at about 350-500 nm, from the S 1 state, were observed. The time profile of the S 2 fluorescence signal is almost equal to the instrument response function, and the lifetime is estimated to be faster than 5 ps. This observation is consistent with the results of transient absorption signals. The S 1 fluorescence signal consists of two decay components. The average lifetimes are 0.88 ns in acetonitrile and 2.0 ns in n-hexane. Nonexponential decay of the fluorescence may result from an equilibrium mixture of the fluorescent state and the conformationally relaxed state. The fluorescence intensity ratio of S 2 to S 1 in solution is much different from that observed in the gas phase. This means that the efficiency of internal conversion increases significantly in solution because of the solute-solvent interactions that are absent in the gas phase. We discuss differences in the excited-state dynamics between 1,3,5-hexatriene and 1,3,5,7-octatetraene.

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Section: Internalmentioning

confidence: 93%

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S₂ to S₁ State and Relaxation Processes in the S₁ State

et al. 2001

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“…The excited state absorption of 1,3,5-hexatriene was not observed by the nanosecond transient absorption spectroscopy due probably to insufficient time resolution . It was suggested that the lifetime of the 2A state was below 200 ps.…”

Section: Introductionmentioning

confidence: 98%

“…15,16 The excited state absorption of 1,3,5-hexatriene was not observed by the nanosecond transient absorption spectroscopy due probably to insufficient time resolution. 17 It was suggested that the lifetime of the 2A state was below 200 ps. Recently, femtosecond spectroscopic studies of 1,3,5-hexatriene and its related compounds in the gas phase revealed that upon excitation of the 1B state the internal conversion to the 2A state occured in less than 100 fs and the vibrational energy redistribution in the S 1 state and the internal conversion to the ground-state proceeded within a subpicosecond time scale.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Transient Absorption Studies oftrans- andcis-1,3,5-Hexatriene in Solution

et al. 1998

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The electronic, vibrational and conformational relaxation of trans- and cis-1,3,5-hexatriene in solution have been investigated by femtosecond transient absorption spectroscopy. Upon excitation to the 1B state, the transient absorption is observed in the visible region, which mainly consists of an instantaneous rise (<150 fs) and a subpicosecond decay. For the trans isomer, the decay of the transient absorption signals becomes faster at longer wavelengths. On the other hand, for the cis isomer, the decay of the signals does not depend on the probe wavelength significantly. For both isomers, these temporal profiles of signals show that the internal conversion from the S2 to S1 state occurs within 100 fs and the lifetime of the S1 state is less than 500 fs. The observed dependence of the decay on the probe wavelengths for the trans isomer is ascribed to vibrational energy redistribution in the S1 state. We also measured the bleach recovery signals by the one-color pump−probe method in the UV region. The bleach recovers in several time scales. The temporal profiles of trans isomer in the first 20 ps are similar to those of cis isomer, which come from the vibrational relaxation in the ground state. However, on a longer time scale, these signals are quite different to each other. While the trans isomer takes 150−300 ps to fully recover the bleach, the cis isomer requires no more than 100 ps. These slow components are attributed to the conformational relaxation around the C−C single bond to the original forms. The different behavior between the trans and cis isomers reflects different product distributions and dynamics among the isomers around the C−C single bonds.

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“…Retinoids and carotenoids are pervasive in biological systems (Carr & Price, 1926; Kildahl‐Andersen et al, 2004; Liaaen‐Jensen & Kildahl‐Andersen, 2008; Lutnaes et al, 2003; Masthay et al, 2002; Mortensen & Skibsted, 2000), but they are seldom used as pH indicators due to their poor water solubility and chemical lability. Even so, upon reacting with electrophiles (like protons or other Lewis acids), the absorption spectra of polyenes undergo significant (>5000 cm –1 ) bathochromic shifts (Horwitz et al, 1981; Kildahl‐Andersen et al, 2004; Liaaen‐Jensen & Kildahl‐Andersen, 2008; Lutnaes et al, 2003; Lutnaes et al, 2002; Mortensen & Skibsted, 2000; Thiele & Streitwieser, 1994). These shifts cause the initially colourless, yellow, orange or red compounds to turn blue.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two diphenyl polyenes as acid‐sensitive additives during the biodegradation of a thermoset polyester polyurethane coating

Shesham

Kelly

Burke

et al. 2021

J of Applied Microbiology

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Aims: Biochemical hydrolysis and chemical catalysis are involved in the successful biodegradation of polymers. In order to evaluate the potential separation between biochemical and chemical catalysis during the biodegradation process, we report the use of two diphenylpolyenes (DPPs), all trans-1,4-diphenylbutadiene (DPB) and all trans-1,6-diphenylhexatriene (DPH), as potential acid-sensitive indicators in polymers. Methods and Results: 1,4-Diphenylbutadiene and DPH (0.1% w/w) were melt-cast successfully with poly(ethylene succinate) hexamethylene (PES-HM) polyurethane (thermoset polyester polyurethane) coatings above 80℃. When these two DPP/ PES-HM coatings were exposed to a concentrated supernatant with significant esterase activity resulting from the growth of a recently isolated and identified strain of Tremellomycetes yeast (Naganishia albida 5307AI), the DPB coatings exhibited a measurable and reproducible localized decrease in the blue fluorescence emission in regions below where hydrolytic biodegradation was initiated in contrast with DPH blended coatings. The fluorescence changes observed in the biodegraded DPB coating were similar to exposing them to concentrated acids and not bases. Conclusions:Our experiments resulted in (1) a method to blend DPP additives into thermoset coatings, (2) the first report of the biodegradation of polyester polyurethane coating by N. albida, and (3) demonstration that hydrolytic supernatants from this strain generate acidic region within degrading polyester coatings using DPB as the indicator.Significance and Impact of the Study: Our experiments confirm that N. albida is an active polyester degrader and that DPB is a promising acid sensitive polymer coating additive.

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Excited-state absorption spectroscopy and state ordering in polyenes

Cited by 14 publications

References 33 publications

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S₂ to S₁ State and Relaxation Processes in the S₁ State

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S₂ to S₁ State and Relaxation Processes in the S₁ State

Femtosecond Transient Absorption Studies oftrans- andcis-1,3,5-Hexatriene in Solution

Comparison of two diphenyl polyenes as acid‐sensitive additives during the biodegradation of a thermoset polyester polyurethane coating

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Excited-state absorption spectroscopy and state ordering in polyenes

Cited by 14 publications

References 33 publications

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S2 to S1 State and Relaxation Processes in the S1 State

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S2 to S1 State and Relaxation Processes in the S1 State

Femtosecond Transient Absorption Studies oftrans- andcis-1,3,5-Hexatriene in Solution

Comparison of two diphenyl polyenes as acid‐sensitive additives during the biodegradation of a thermoset polyester polyurethane coating

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Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S₂ to S₁ State and Relaxation Processes in the S₁ State

Excited-State Dynamics of all-trans-1,3,5,7-Octatetraene in Solution. Direct Observation of Internal Conversion from the S₂ to S₁ State and Relaxation Processes in the S₁ State