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Fluorine induced conformational switching and modulation in photophysical properties of 7-fluorotryptophan: Spectroscopic, quantum chemical calculation and molecular dynamics simulation studies. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2020. [DOI: 10.1016/j.jpap.2020.100011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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2
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Subramaniam R, Lynch S, Cen Y, Balaz S. Polarity of Hydrated Phosphatidylcholine Headgroups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8460-8471. [PMID: 31244216 PMCID: PMC6853183 DOI: 10.1021/acs.langmuir.8b03992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The headgroup (H) stratum (sometimes called the polar region) of membrane bilayers is a relevant yet poorly understood solvation phase for small molecules and macromolecules interacting with the membranes. Solvation of compounds in bilayer strata is characterized experimentally by wide- and small-angle X-ray scattering, neutron diffraction, and various NMR techniques. The quantification is tedious and only available for a limited set of small molecules. Our recently published model of liposome partitioning of small molecules shows that solvation of compounds in the H-stratum of fluid phosphatidylcholine (PC) bilayers correlates well with their solvation in hydrated diacetyl phosphatidylcholine (DAcPC), and solvation in the core (C) depends in a similar way on that in n-hexadecane. These two correlations became a basis for a model describing the location of compounds in the H- and C-strata and at the connecting interface as a nonlinear function of the fragment solvation characteristics of the compounds. In this study, refractivity of hydrated DAcPC phases with varying water contents was measured and polarity was determined using the steady-state fluorescence of indole and Nile Red. The results were compared with the published data obtained by other techniques for PC bilayers in liposomes or on solid supports. The demonstrated qualitative agreement, as well as the polarity and refractivity dependencies on the DAcPC concentration, supports the suitability of hydrated DAcPC as the H-stratum surrogate. Interestingly, depending on hydrations typical for the H-strata of fluid PC bilayers, the dielectric constant could decrease significantly from 31.0 to 7.3 for 16 and 8 water molecules per headgroup, respectively. Although additional experiments are needed for confirmation, this observation could help set proper dielectric constant magnitudes in continuum-based computational models of accumulation and crossing of the PC bilayers with varying hydration levels thanks to the temperature or the structure of fatty acid chains.
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Affiliation(s)
| | | | | | - Stefan Balaz
- Corresponding author: Stefan Balaz, Albany College of Pharmacy and Health Sciences, Vermont Campus, Department of Pharmaceutical Sciences, 261 Mountain View Road, Colchester, VT 05446, United States, phone 802-735-2615,
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3
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Wilke J, Wilke M, Brand C, Meerts WL, Schmitt M. On the Additivity of Molecular Fragment Dipole Moments of 5-Substituted Indole Derivatives. Chemphyschem 2016; 17:2736-43. [DOI: 10.1002/cphc.201600420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Josefin Wilke
- Heinrich-Heine-Universität; Institut für Physikalische Chemie I; D-40225 Düsseldorf Germany
| | - Martin Wilke
- Heinrich-Heine-Universität; Institut für Physikalische Chemie I; D-40225 Düsseldorf Germany
| | - Christian Brand
- Heinrich-Heine-Universität; Institut für Physikalische Chemie I; D-40225 Düsseldorf Germany
- University of Vienna; Faculty of Physics, VCQ; Boltzmanngasse 5 A-1090 Vienna Austria
| | - W. Leo Meerts
- Radboud University; Institute for Molecules and Materials, Felix laboratory; Toernooiveld 7c 6525 ED Nijmegen The Netherlands
| | - Michael Schmitt
- Heinrich-Heine-Universität; Institut für Physikalische Chemie I; D-40225 Düsseldorf Germany
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4
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Sengupta B, Mukherjee P, Das S, Rafiq S, Gupta S, Dethe DH, Sen P. Femtosecond dynamics of photoinduced cis-trans isomerization of ethyl-3-(1H-indole-3-yl)acrylate. Chem Phys Lett 2015. [DOI: 10.1016/j.cplett.2015.08.025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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5
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Brisker-Klaiman D, Dreuw A. Explaining Level Inversion of the Laand LbStates of Indole and Indole Derivatives in Polar Solvents. Chemphyschem 2015; 16:1695-702. [DOI: 10.1002/cphc.201500073] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 02/16/2015] [Indexed: 12/23/2022]
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6
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Catalán J. Fluorosolvatochromism of monomethyl indoles: further evidence in support of a new photophysical model for the indole chromophore. J PHYS ORG CHEM 2015. [DOI: 10.1002/poc.3414] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Javier Catalán
- Departamento de Química Física Aplicada; Universidad Autónoma de Madrid; Cantoblanco Madrid Spain
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7
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Herbrich S, Al-Hadhuri T, Gericke KH, Shternin PS, Smolin AG, Vasyutinskii OS. Two-color two-photon excited fluorescence of indole: Determination of wavelength-dependent molecular parameters. J Chem Phys 2015; 142:024310. [DOI: 10.1063/1.4905140] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Sebastian Herbrich
- Institut für Physikalische und Theoretische Chemie, TU Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany
| | - Tawfik Al-Hadhuri
- Institut für Physikalische und Theoretische Chemie, TU Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany
| | - Karl-Heinz Gericke
- Institut für Physikalische und Theoretische Chemie, TU Braunschweig, Hans-Sommer-Straße 10, 38106 Braunschweig, Germany
| | - Peter S. Shternin
- Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
- St. Petersburg Polytechnic University, Politekhnicheskaya 29, St. Petersburg 195251, Russia
| | - Andrey G. Smolin
- Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
| | - Oleg S. Vasyutinskii
- Ioffe Institute, Politekhnicheskaya 26, 194021 St. Petersburg, Russia
- St. Petersburg Polytechnic University, Politekhnicheskaya 29, St. Petersburg 195251, Russia
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8
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Catalán J. The first UV absorption band for indole is not due to two simultaneous orthogonal electronic transitions differing in dipole moment. Phys Chem Chem Phys 2015; 17:12515-20. [PMID: 25899470 DOI: 10.1039/c5cp01170a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Polarization of the indole in glycerol: at 223 K (1Lb with P0 = 0.38) and at 283 K (1La with P0 = 0.18).
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Affiliation(s)
- Javier Catalán
- Departamento de Química Física Aplicada
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
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McMillan AW, Kier BL, Shu I, Byrne A, Andersen NH, Parson WW. Fluorescence of tryptophan in designed hairpin and Trp-cage miniproteins: measurements of fluorescence yields and calculations by quantum mechanical molecular dynamics simulations. J Phys Chem B 2013; 117:1790-809. [PMID: 23330783 PMCID: PMC3581364 DOI: 10.1021/jp3097378] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The quantum yield of tryptophan (Trp) fluorescence was measured in 30 designed miniproteins (17 β-hairpins and 13 Trp-cage peptides), each containing a single Trp residue. Measurements were made in D(2)O and H(2)O to distinguish between fluorescence quenching mechanisms involving electron and proton transfer in the hairpin peptides, and at two temperatures to check for effects of partial unfolding of the Trp-cage peptides. The extent of folding of all the peptides also was measured by NMR. The fluorescence yields ranged from 0.01 in some of the Trp-cage peptides to 0.27 in some hairpins. Fluorescence quenching was found to occur by electron transfer from the excited indole ring of the Trp to a backbone amide group or the protonated side chain of a nearby histidine, glutamate, aspartate, tyrosine, or cysteine residue. Ionized tyrosine side chains quenched strongly by resonance energy transfer or electron transfer to the excited indole ring. Hybrid classical/quantum mechanical molecular dynamics simulations were performed by a method that optimized induced electric dipoles separately for the ground and excited states in multiple π-π* and charge-transfer (CT) excitations. Twenty 0.5 ns trajectories in the tryptophan's lowest excited singlet π-π* state were run for each peptide, beginning by projections from trajectories in the ground state. Fluorescence quenching was correlated with the availability of a CT or exciton state that was strongly coupled to the π-π* state and that matched or fell below the π-π* state in energy. The fluorescence yields predicted by summing the calculated rates of charge and energy transfer are in good accord with the measured yields.
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Affiliation(s)
- Andrew W. McMillan
- Department of Biochemistry, Structure and Design, University of Washington, Seattle, WA 98195
- Program in Biological Physics, Structure and Design, University of Washington, Seattle, WA 98195
| | - Brandon L. Kier
- Department of Chemistry, Structure and Design, University of Washington, Seattle, WA 98195
- Program in Biological Physics, Structure and Design, University of Washington, Seattle, WA 98195
| | - Irene Shu
- Department of Chemistry, Structure and Design, University of Washington, Seattle, WA 98195
| | - Aimee Byrne
- Department of Chemistry, Structure and Design, University of Washington, Seattle, WA 98195
| | - Niels H. Andersen
- Department of Chemistry, Structure and Design, University of Washington, Seattle, WA 98195
- Program in Biological Physics, Structure and Design, University of Washington, Seattle, WA 98195
| | - William W. Parson
- Department of Biochemistry, Structure and Design, University of Washington, Seattle, WA 98195
- Program in Biological Physics, Structure and Design, University of Washington, Seattle, WA 98195
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Catalán J, Catalán JP. Questioning the photophysical model for the indole chromophore in the light of evidence obtained by controlling the non-specific effect of the medium with 1-chlorobutane as solvent. Phys Chem Chem Phys 2011; 13:15022-30. [PMID: 21761037 DOI: 10.1039/c1cp21380f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this work, we substantiate the change in the emitting state of indole caused by the dipolarity increase in the solvent 1-chlorobutane, observed on lowering the temperature from 293 to 133 K, accompanied by no significant changes in the corresponding excitation and absorption spectra. No similar changes in indole emission were observed over the temperature range 293-133 K for solutions of indole in 2-methylbutane in the presence and absence of 0.5 M 1-chlorobutane. The solvatochromism of indole in 1-chlorobutane at temperatures from 293 to 133 K allowed us to estimate the dipole moment and polarizability of the emission state of the chromophore and to detect two states (S(1) and ): one, the S(1), involving no significant change and the other, the , exhibiting a substantial change in the dipole moment of the chromophore upon electronic excitation (viz. μ(S(1)) = 2.5 and vs. μ(S(0)) = 2.13 D). The former state, S(1), is the major contributor to the structured emission of indole at temperatures from 293 to 193 K, as is the latter, S'(1) , to its structureless, red-shifted emission over the range 193-133 K. Although the emission changes of indole, dissolved in 1-chlorobutane at temperatures from 293 to 133 K, are seemingly consistent with the widely accepted photophysical model for inversion of its (1)L(b) and (1)L(a) states as the polarity of the medium is increased, below 133 K the emission becomes structured and blue-shifted, two typical features of indole above 193 K. Also, below 123 K is not feasible to photo-select the (1)L(a) state in spite of this state being the first excited electronic state of indole under large dipolarity conditions. Therefore, the established photophysical model cannot hold under these conditions and a new one accounting for these experimental facts is proposed instead.
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Affiliation(s)
- Javier Catalán
- Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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11
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Wang C, Feng L, Liu L, Wang Y, Qiao L, Ni J, Xu J. Photoactivated green fluorescence emission by femtosecond oscillator from indole solutions. J Fluoresc 2011; 21:2185-91. [PMID: 21744315 DOI: 10.1007/s10895-011-0921-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 07/04/2011] [Indexed: 11/30/2022]
Abstract
We reported a novel femtosecond-laser-activated fluorescence emission from indole solutions upon excitation by the second harmonic wavelength of a femtosecond oscillator. A new absorption band around 400 nm and corresponding fluorescent band in the green domain were produced after the irradiation of femtosecond laser. This femtosecond-laser-activated luminescence process that allows the use of visible wavelength as a substitute for UV light to excite fluorescence from indole would extend applications based on indole chromophore. Furthermore, the photoactived emission can act as a fluorescence lifetime probe to measure the polarity in complex biological systems since it is polarity-sensitive. High performance liquid chromatography with fluorescence detector (HPLC-FLU) and high performance liquid chromatography with mass spectrometer (HPLC-MS) analysis demonstrate that the origin of the photoactivated fluorescence is new molecular species that generated in indole solution upon femtosecond laser irradiation.
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Affiliation(s)
- Chen Wang
- State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
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12
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Citroni M, Costantini B, Bini R, Schettino V. Crystalline indole at high pressure: chemical stability, electronic, and vibrational properties. J Phys Chem B 2009; 113:13526-35. [PMID: 19769333 DOI: 10.1021/jp907169p] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vibrational and electronic spectra of crystalline indole were measured up to 25.5 GPa at room temperature in a diamond anvil cell. In particular, Fourier transform infrared (FTIR) spectra in the mid-infrared region and two-photon excitation profiles and fluorescence spectra in the region of the HOMO-LUMO transitions were obtained. The analysis of the FTIR spectra revealed a large red-shift of the N-H stretching mode with increasing pressure, indicating the strengthening of the H-bond between the NH group and the pi electron density of nearest neighbor molecules. The frequencies of four vibronic bands belonging to the (1)L(a) and (1)L(b) systems were obtained as a function of pressure. Comparison with literature data shows that the crystal acts as a highly polar environment with regard to the position of the (1)L(b) origin and of the fluorescence maximum, which are largely red-shifted with respect to the gas phase or to solutions in apolar solvents. A large, and increasing with pressure, frequency difference between the (1)L(b) origin and the blue edge of the fluorescence spectrum suggests that the emitting state is (1)L(a), that is known to be more stabilized than (1)L(b) by dipolar relaxation. Crystalline indole was found to be very stable with respect to pressure-induced reactivity. Only traces of a reaction product, containing saturated C-H bonds, are detected after a full compression-decompression cycle. In addition, differently from many unsaturated compounds at high pressure, irradiation with light matching a two-photon absorption for a HOMO-LUMO transition has no enhancing effect on reactivity. The chemical stability of indole at high pressure is ascribed to the crystal structure, where nearest neighbor molecules, formig H-bonds, are not in a favorable position to react, while reaction between equivalent molecules, for which a superposition of the pi electron clouds would be possible, is hindered by H-bonded molecules. Consistently, no excimer emission was observed except at the cell opening at the end of the compression-decompression run. Extremely limited chemical reactivity and excimer formation likely occur at crystal defects, evidencing the strict connection between the two phenomena.
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Affiliation(s)
- Margherita Citroni
- LENS - European Laboratory for Nonlinear Spectroscopy, Universitá di Firenze, via N. Carrara 1, I-50019 Sesto F.no (FI), Italy.
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13
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Catalán J. Toward a Generalized Treatment of the Solvent Effect Based on Four Empirical Scales: Dipolarity (SdP, a New Scale), Polarizability (SP), Acidity (SA), and Basicity (SB) of the Medium. J Phys Chem B 2009; 113:5951-60. [DOI: 10.1021/jp8095727] [Citation(s) in RCA: 494] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Javier Catalán
- Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, E-28024 Madrid, Spain
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14
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Pollet R, Brenner V. Assessment of time-dependent density functional theory for predicting excitation energies of bichromophoric peptides: case of tryptophan-phenylalanine. Theor Chem Acc 2008. [DOI: 10.1007/s00214-008-0479-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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Rogers DM, Besley NA, O'Shea P, Hirst JD. Modeling the absorption spectrum of tryptophan in proteins. J Phys Chem B 2007; 109:23061-9. [PMID: 16854004 DOI: 10.1021/jp053309j] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have applied time-dependent density functional theory (TDDFT) to study the valence pi-pi* excited states of the tryptophan chromophore in the environment of the proteins barnase and human serum albumin. The chromophore is represented by indole. Due to the approximate nature of TDDFT, in the gas phase the calculated vertical transition energies to the 1L valence states are reordered with respect to experiment. The 1L(a) state responds more than the 1L(b) state to the local environment, described fully at the TDDFT level, and to bulk environment, described by a set of point charges. Nevertheless, the vertical transitions are readily identified. For human serum albumin, our calculations predict distinct spectral characteristics between structures with different tryptophan side chain torsion angles. The computational tractability of TDDFT relative to more accurate ab initio methods allows a large part of the surrounding protein environment (up to 100 atoms) to be explicitly included in the TDDFT calculations.
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Affiliation(s)
- David M Rogers
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
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Muñoz MA, Carmona C, Balón M. FTIR and fluorescence studies on the ground and excited state hydrogen-bonding interactions between 1-methylindole and water in water–triethylamine mixtures. Chem Phys 2007. [DOI: 10.1016/j.chemphys.2007.01.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Kyrychenko A, Waluk J. Excited-state proton transfer through water bridges and structure of hydrogen-bonded complexes in 1H-pyrrolo[3,2-h]quinoline: adiabatic time-dependent density functional theory study. J Phys Chem A 2007; 110:11958-67. [PMID: 17064184 DOI: 10.1021/jp063426u] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Proton transfer reaction is studied for 1H-pyrrolo[3,2-h]quinoline-water complexes (PQ-(H(2)O)(n), n = 0-2) in the ground and the lowest excited singlet states at the density functional theory (DFT) level. Cyclic hydrogen-bonded complexes are considered, in which water molecules form a bridge connecting the proton donor (pyrrole NH group) and acceptor (quinoline nitrogen) atoms. To understand the effect of the structure and length of water bridges on the excited-state tautomerization in PQ, the potential energy profile of the lowest excited singlet state is calculated adiabatically by the time-dependent DFT (TDDFT) method. The S(0) --> S(1) excitation of PQ is accompanied by significant intramolecular transfer of electron density from the pyrrole ring to the quinoline fragment, so that the acidity of the N-H group and the basicity of the nitrogen atom of the quinoline moiety are increased. These excited-state acid-base changes introduce a driving force for the proton transfer reaction. The adiabatic TDDFT calculations demonstrate, however, that the phototautomerization requires a large activation energy in the isolated PQ molecule due to a high energy barrier separating the normal form and the tautomer. In the 1:1 cyclic PQ-H(2)O complex, the energy barrier is dramatically reduced, so that upon excitation of this complex the tautomerization can occur rapidly in one step as concerted asynchronous movements of the two protons assisted by the water molecule. In the PQ-(H(2)O)(2) solvate two water molecules form a cyclic bridge with sterically strained and unfavorable hydrogen bonds. As a result, some extra activation energy is needed for initiating the proton dislocation along the longer hydrogen-bond network. The full tautomerization in this complex is still possible; however, the cooperative proton transfer is found to be highly asynchronous. Large relaxation and reorganization of the hydrogen-bonded water bridge in PQ-(H(2)O)(2) are required during the proton translocation from the pyrrole NH group to the quinoline nitrogen; this may block the complete tautomerization in this type of solvate.
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Affiliation(s)
- A Kyrychenko
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland
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Sharma N, Jain SK, Rastogi RC. Solvatochromic study of excited state dipole moments of some biologically active indoles and tryptamines. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 66:171-6. [PMID: 16829174 DOI: 10.1016/j.saa.2006.02.039] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2005] [Accepted: 02/22/2006] [Indexed: 05/10/2023]
Abstract
Absorption and fluorescence spectra of some biologically active indole and tryptamine derivatives have been recorded at room temperature in solvents of different polarities. The interest in the photophysical properties of these molecules arises mainly from their utility in medicinal chemistry as neurotransmitter and hallucination/hallucinic agents. Excited-state dipole moments of these molecules have been estimated from solvent-dependent Stokes shift data using a solvatochromic method based on a microscopic solvent polarity parameter (ETN). All indoles show a substantial increase in the dipole moment upon excitation to the emitting state. These results are generally consistent with the Parametric Method 3 (PM3) calculations, and are found to be quite reliable in view of the fact that the correlation of the solvatochromic Stokes shifts with the microscopic solvent polarity parameter (ETN) is superior to that obtained using bulk solvent polarity functions.
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Affiliation(s)
- Neera Sharma
- Department of Chemistry, University of Delhi, Delhi 110007, India
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Jalviste E, Ohta N. Stark absorption spectroscopy of indole and 3-methylindole. J Chem Phys 2004; 121:4730-9. [PMID: 15332907 DOI: 10.1063/1.1782076] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Indole and 3-methylindole (3-MI) doped into a polymethylmethacrylate (PMMA) film are studied by the Stark absorption (electroabsorption) spectroscopy. The 1La and 1Lb absorption bands are distinguished and the change in permanent dipole moment on 1La excitation is determined by a model fit to the measured absorption and electroabsorption spectra. Analysis of the spectra, measured at normal incidence and magic angle conditions, proved the essential role of the electric-field-induced orientation/alignment effects for polar indole and 3-MI molecules in the PMMA environment at room temperature.
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Affiliation(s)
- Erko Jalviste
- Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia.
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Muñoz MA, Carmona C, Balón M. The ground and singlet excited-state hydrogen-bonding interactions of N-methylindole with trifluoroethanol in n-hexane: a model to explain the anomalous fluorescence of indole in polar protic solvents. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.06.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Lotte K, Plessow R, Brockhinke A. Static and time-resolved fluorescence investigations of tryptophan analogues--a solvent study. Photochem Photobiol Sci 2004; 3:348-59. [PMID: 15052363 DOI: 10.1039/b312436c] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The fluorescence properties of tryptophan, polytryptophan and seven of its analogues (7-azatryptophan, 5-hydroxytryptophan, 5-methoxytryptophan, 5-fluorotryptophan, 5-methyltryptophan, 5-bromotryptophan, and 6-fluorotryptophan) are studied using two novel fluorescence spectroscopic techniques for a wide range of solvent polarities. Two-dimensional mapping of all emission and all fluorescence spectra using excitation-emission spectroscopy (EES) has been used to determine quantum yields, positions of emission maxima, full widths at half maximum (FWHMs) as well as Stokes' shifts. Additionally, fluorescence lifetimes obtained from time-resolved experiments using a picosecond laser system are presented and compared with the data acquired from the static setup. This systematic study of the fluorescence characteristics is a prerequisite to assess the potential of these analogues to act as structure-conserving substitutes for tryptophan in protein fluorescence experiments. The potential of these analogues, to act as probes for the local environment, and allow estimation of the polarity in the vicinity of the fluorophore and its exposure to the solvent, is discussed.
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Affiliation(s)
- Kirsten Lotte
- Physikalische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, D-33615 Bielefeld, Germany
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22
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Rogers DM, Hirst JD. Ab Initio Study of Aromatic Side Chains of Amino Acids in Gas Phase and Solution. J Phys Chem A 2003. [DOI: 10.1021/jp036081d] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- David M. Rogers
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
| | - Jonathan D. Hirst
- School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD, United Kingdom
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