1La transitions of jet-cooled 3-methylindole

Sammeth, David M.; Siewert, Sonja S.; Spangler, Lee H.; Callis, Patrik R.

doi:10.1016/0009-2614(92)85844-z

Cited by 37 publications

(34 citation statements)

References 24 publications

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“…All were earlier assigned to be 1 L a except for the peak at 429 cm -1 . 17 While there are peaks in the water complex spectrum at 403 and 451 cm -1 that could conceivably be associated with the 429 cm -1 3-MI peak, there appears to be no corresponding peak in the methanol complex.…”

Section: -Mimentioning

confidence: 94%

Jet-Cooled Solvent Complexes with Indoles

and

Sulkes

1996

J. Phys. Chem.

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Cold mass-resolved excitation spectra have been obtained for substituted and unsubstituted indoles complexed with one or two polar solvent molecules. Frequency scans were carried out to more than 1000 cm -1 above the complex origins. Sharp excitation features persisted to the blue for the N-H site complexes, but no features further to the blue were attributable to the π site complexes. In 3-methylindole a number of vibrations 400-900 cm -1 above the S 1 origin in the bare chromophore did not appear in corresponding locations above the S 1 complex origins for n ) 1 water and methanol clusters. It is likely that these peaks underwent much greater red shifts in the complexes than the S 1 origins because the former possess substantial 1 L a character. Any of the indoles studied that was complexed with two polar solvent molecules showed broad excitation features. The extended structure most likely arises in at least some instances because of π site interactions. In 2,3-dimethylindole, postulated to undergo N-H bond dissociation in S 1 , mass-resolved REMPI spectra did not disclose a lower mass product arising from N-H bond breaking. However, when the chromophore was complexed at the N-H site with a strong proton acceptor, triethylamine, evidence was found that zwitterions were formed in the S 1 complex arising from N-H site proton donation to the base.

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Section: -Mimentioning

confidence: 94%

Jet-Cooled Solvent Complexes with Indoles

and

Sulkes

1996

J. Phys. Chem.

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“…Trp max is quite sensitive to its local environment, ranging from ϳ308 nm (azurin) to ϳ355 nm (e.g., glucagon) and roughly correlates with the degree of solvent exposure of the chromophore. However, wavelength information, when interpreted, is universally done in a fashion that does not exploit the substantial amount of detail concerning the two lowest excited electronic states of Trp, 1 L a and 1 L b , that has emerged from two-photon excitation (Callis and Rehms, 1993;Muiño and Callis, 1994a;Rehms and Callis, 1987;Sammeth et al, 1990Sammeth et al, , 1992, jet-cooled and argon matrix spectra (Fender et al, 1995;Fender and Callis, 1996;Sammeth et al, 1992), Stark spectroscopy (Pierce and Boxer, 1995), and hybrid quantum mechanicalmolecular dynamics simulations (Muiño and Callis, 1994b, c;Callis and Burgess, 1997). What is important here is that the detailed experimental data are well-supported by a variety of semiempirical and ab initio quantum chemical studies (Callis et al, 1995;Chabalowski et al, 1993;Hahn and Callis, 1997;Serrano-Andres and Roos, 1996;Slater and Callis, 1995) [some of this work has been reviewed recently (Callis, 1997)].…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Tryptophan Fluorescence Shifts in Proteins

Vivian

Callis

2001

Biophysical Journal

1,281

1,128

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Tryptophan fluorescence wavelength is widely used as a tool to monitor changes in proteins and to make inferences regarding local structure and dynamics. We have predicted the fluorescence wavelengths of 19 tryptophans in 16 proteins, starting with crystal structures and using a hybrid quantum mechanical-classical molecular dynamics method with the assumption that only electrostatic interactions of the tryptophan ring electron density with the surrounding protein and solvent affect the transition energy. With only one adjustable parameter, the scaling of the quantum mechanical atomic charges as seen by the protein/solvent environment, the mean absolute deviation between predicted and observed fluorescence maximum wavelength is 6 nm. The modeling of electrostatic interactions, including hydration, in proteins is vital to understanding function and structure, and this study helps to assess the effectiveness of current electrostatic models.

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“…In the case of rarefied vapor, they are exclusively a property of the molecules themselves and match data obtained in studying the fluorescence excitation spectra of molecules cooled in a supersonic jet. For indole cooled in a supersonic jet, according to the data in [10,11], the frequency of the purely electronic transition between the electronic ground state and the first excited electronic state 1 L b is ν EL 1 = 35,231 cm -1 , while the frequency of the transition between the ground state and the second electronically excited state 1 L a is ν EL 2 = 36,631 cm -1 .…”

Section: Introductionmentioning

confidence: 99%

Absorption, fluorescence, and fluorescence excitation spectra of free molecules of indole and its derivatives

Borisevich

Райченок

2007

J Appl Spectrosc

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We have obtained and analyzed the absorption, fluorescence, and fluorescence excitation spectra of indole vapor, N-acetyl-L-tryptophan vapor, and 3-indole aldehyde vapor. From analysis of the dependence of the fluorescence spectrum of the free indole molecules on the wavelength of the exciting radiation λ ex , it follows that emission of fluorescence occurs when the molecules undergo a transition from the one electronically excited state 1 L b . The fluorescence spectra of the studied compounds are insignificantly different, suggesting a major role for the indole chromophore in formation of the compounds. The absorption spectrum of N-acetyl-L-tryptophan, in which the group of atoms is added to the indole ring through a -C-C bond, is similar to the spectrum of indole, while the spectrum of 3-indole aldehyde is significantly different from the indole spectrum due to the effect of the C=O group conjugated with the indole ring. The fluorescence excitation spectra are considerably different from the absorption spectra. This is associated with the strong dependence of the quantum yield for the free molecules on λ ex . Qualitatively, they are mirror-symmetric to the fluorescence spectra of the stodied compounds. Analysis of the data obtained provides a basis for assuming that in the case of free molecules of indole and its derivatives, the 1 L a absorption in the extreme long-wavelength region of the spectrum does not overlap 1 L b absorption.Introduction. Indole is a chromophore in the amino acid series including tryptophan, the luminescence of which is used when studying complex biological systems. It is well known that the medium has a strong effect on the photophysical properties of indole. Accordingly, broad studies have been conducted on different solutions of indole and its derivatives. The results obtained are covered in monographs [1-3] and many other publications, including theoretical papers [4,5]. It is important to study these molecules in the gas phase (where they do not interact with a medium but rather are free molecules), especially rarefied vapor, where they do not interact with each other during the lifetime of the molecules in the excited electronic state. However, there have only been isolated studies of indole and its derivatives in the gas phase.The first data on the absorption spectrum of indole vapor are found in [6], where the authors associate the longest wavelength band in the spectrum with the electronic transition 1 L b , and the maximum of this band at λ max = 283.7 nm is assumed to correspond to a purely electronic transition. A group of weak bands is also assigned to the same electronic transition. The absorption band with maximum wavelength λ max = 274.1 nm, like the subsequent bands at λ max = 260 and 255 nm, is assigned to the second electronic transition 1 L a . This absorption spectrum of indole vapor is given in the monographs [1,2]. In [6], the absorption spectrum of 3-methylindole vapor is obtained, while [7] gives the spectrum of 5-methoxyindole. A problem with these papers was ...

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1La transitions of jet-cooled 3-methylindole

Cited by 37 publications

References 24 publications

Jet-Cooled Solvent Complexes with Indoles

Jet-Cooled Solvent Complexes with Indoles

Mechanisms of Tryptophan Fluorescence Shifts in Proteins

Absorption, fluorescence, and fluorescence excitation spectra of free molecules of indole and its derivatives

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