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Kumar V. 2-Naphthoic acid prototropism within ionic liquid based media. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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2
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Checcucci G, Storti B, Ghetti F, Signore G, Bizzarri R. Fluorescence lifetime microscopy reveals the biologically-related photophysical heterogeneity of oxyblepharismin in light-adapted (blue) Blepharisma japonicum cells. Photochem Photobiol Sci 2017. [PMID: 28636018 DOI: 10.1039/c7pp00072c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The step-up photophobic response of the heterotrich ciliate Blepharisma japonicum is mediated by a hypericinic pigment, blepharismin, which is not present in any of the known six families of photoreceptors, namely rhodopsins, phytochromes, xanthopsins, cryptochromes, phototropins, and BLUF proteins. Upon irradiation, native cells become light-adapted (blue) by converting blepharismin into the photochemically stable oxyblepharismin (OxyBP). So far, OxyBP has been investigated mainly from a photophysical point of view in vitro, either alone or complexed with proteins. In this work, we exploit the vivid fluorescence of OxyBP to characterize its lifetime emission in blue B. Japonicum cells, on account of the recognized role of the fluorescence lifetime to provide physicochemical insights into the fluorophore environment at the nanoscale. In a biological context, OxyBP modifies its emission lifetime as compared to isotropic media. The phasor approach to fluorescence lifetime microscopy in confocal mode highlights that fluorescence originates from two excited states, whose relative balance changes throughout the cell body. Additionally, Cilia and kinetids, i.e., the organelles involved in photomovement, display lifetime asymmetry between the anterior and posterior part of the cell. From these data, some hypotheses on the phototransduction mechanism are proposed.
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Affiliation(s)
- G Checcucci
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa, Italy.
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Kumar V, Pandey A, Pandey S. Proton-Transfer Reactions of Acridine in Water-Containing Ionic-Liquid-Rich Mixtures. Chemphyschem 2013; 14:3944-52. [DOI: 10.1002/cphc.201300817] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 09/25/2013] [Indexed: 11/11/2022]
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4
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Zhang W, Gong X, Cai Y, Zhang C, Yu X, Fan J, Diao G. Investigation of water-soluble inclusion complex of hypericin with β-cyclodextrin polymer. Carbohydr Polym 2013; 95:366-70. [DOI: 10.1016/j.carbpol.2013.03.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Accepted: 03/03/2013] [Indexed: 11/25/2022]
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Kumar V, Pandey S. Selective Quenching of 2-Naphtholate Fluorescence by Imidazolium Ionic Liquids. J Phys Chem B 2012; 116:12030-7. [DOI: 10.1021/jp3080817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Vinod Kumar
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Siddharth Pandey
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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6
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Yang IS, Jin SM, Kang JH, Ramanathan V, Kim HM, Suh YD, Kim SK. Excited State Dynamics of Curcumin and Solvent Hydrogen Bonding. B KOREAN CHEM SOC 2011. [DOI: 10.5012/bkcs.2011.32.8.3090] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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7
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Kee TW, Adhikary R, Carlson PJ, Mukherjee P, Petrich JW. Femtosecond Fluorescence Upconversion Investigations on the Excited-State Photophysics of Curcumin. Aust J Chem 2011. [DOI: 10.1071/ch10417] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The demonstration of curcumin as a photodynamic therapy agent has generated a high level of interest in understanding the photoinduced chemical and physical properties of this naturally occurring, yellow-orange medicinal compound. Important photophysical processes that may be related to photodynamic therapy effects including excited-state intramolecular hydrogen atom transfer (ESIHT) occur within the femtosecond to picosecond time scales. Femtosecond fluorescence upconversion spectroscopy has sufficient time resolution to resolve and investigate these important photophysical processes. In this review, recent advances in using femtosecond fluorescence upconversion to reveal ultrafast solvation and ESIHT of curcumin are presented. The excited-state photophysics of curcumin has been investigated in alcohols and micellar solutions. The results of curcumin in methanol and ethylene glycol reveal the presence of two decay components in the excited-state kinetics with time scales of 12–20 ps and ∼100 ps. Similarly, in a micellar solution, biphasic kinetics are present with the fast decay component having a time constant of 3–8 ps, the slow decay component 50–80 ps. Deuteration of curcumin in both media leads to a pronounced isotope effect in the slow decay component, which suggests that ESIHT is an important photophysical process on this time scale. The results of multiwavelength fluorescence upconversion studies show that the fast component in the excited-state kinetics is due to ultrafast solvation. These advances form a part of the continuing efforts to elucidate the photodynamic therapy properties of curcumin.
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Adhikary R, Carlson PJ, Kee TW, Petrich JW. Excited-state intramolecular hydrogen atom transfer of curcumin in surfactant micelles. J Phys Chem B 2010; 114:2997-3004. [PMID: 20136104 DOI: 10.1021/jp9101527] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Femtosecond fluorescence upconversion experiments were performed on the naturally occurring medicinal pigment, curcumin, in anionic, cationic, and neutral micelles. In our studies, the micelles are composed of sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium bromide (DTAB), and triton X-100 (TX-100). We demonstrate that the excited-state kinetics of curcumin in micelles have a fast (3-8 ps) and slow (50-80 ps) component. While deuteration of curcumin has a negligible effect on the fast component, the slow component exhibits a pronounced isotope effect of approximately 1.6, indicating that micelle-captured curcumin undergoes excited-state intramolecular hydrogen atom transfer. Studies of solvation dynamics of curcumin in a 10 ps time window reveal a fast component (< or = 300 fs) followed by a 8, 6, and 3 ps component in the solvation correlation function for the TX-100, DTAB, and SDS micelles, respectively.
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Adhikary R, Mukherjee P, Kee TW, Petrich JW. Excited-State Intramolecular Hydrogen Atom Transfer and Solvation Dynamics of the Medicinal Pigment Curcumin. J Phys Chem B 2009; 113:5255-61. [DOI: 10.1021/jp901234z] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Ramkrishna Adhikary
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, and School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Prasun Mukherjee
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, and School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Tak W. Kee
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, and School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Jacob W. Petrich
- Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, and School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia, 5005, Australia
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Liang YH, Yi PG, Peng HL. Theoretical study of structure, energetic and intramolecular hydrogen transfer of hypocrellin A. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.09.074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Lobban CS, Hallam SJ, Mukherjee P, Petrich JW. Photophysics and Multifunctionality of Hypericin-Like Pigments in Heterotrich Ciliates: A Phylogenetic Perspective. Photochem Photobiol 2007; 83:1074-94. [PMID: 17880503 DOI: 10.1111/j.1751-1097.2007.00191.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, we review the literature and present some new data to examine the occurrence and photophysics of the diverse hypericin-like chromophores in heterotrichs, the photoresponses of the cells, the various roles of the pigments and the taxa that might be studied to advance our understanding of these pigments. Hypericin-like chromophores are known chemically and spectrally so far only from the stentorids and Fabrea, the latter now seen to be sister to stentorids in the phylogenetic tree. For three hypericin-like pigments, the structures are known but these probably do not account for all the colors seen in stentorids. At least eight physiological groups of Stentor exist depending on pigment color and presence/absence of zoochlorellae, and some species can be bleached, leading to many opportunities for comparison of pigment chemistry and cell behavior. Several different responses to light are exhibited among heterotrichs, sometimes by the same cell; in particular, cells with algal symbionts are photophilic in contrast to the well-studied sciaphilous (shade-loving) species. Hypericin-like pigments are involved in some well-known photophobic reactions but other pigments (rhodopsin and flavins) are also involved in photoresponses in heterotrichs and other protists. The best characterized role of hypericin-like pigments in heterotrichs is in photoresponses and they have at least twice evolved a role as photoreceptors. However, hypericin and hypericin-like pigments in diverse organisms more commonly serve as predator defense and the pigments are multifunctional in heterotrichs. A direct role for the pigments in UV protection is possible but evidence is equivocal. New observations are presented on a folliculinid from deep water, including physical characterization of its hypericin-like pigment and its phylogenetic position based on SSU rRNA sequences. The photophysics of hypericin and hypericin-like pigments is reviewed. Particular attention is given to how their excited-state properties are modified by the environment. Dramatic changes in excited-state behavior are observed as hypericin is moved from the homogeneous environment of organic solvents to the much more structured surroundings provided by the complexes it forms with proteins. Among these complexes, it is useful to consider the differences between environments where hypericin is not found naturally and those where it is, notably, for example, in heterotrichs. It is clear that interaction with a protein modifies the photophysics of hypericin and understanding the molecular basis of this interaction is one of the outstanding problems in elucidating the function of hypericin and hypericin-like chromophores.
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Sanders L, Halder M, Xiao TL, Ding J, Armstrong DW, Petrich JW. The Separation of Hypericin's Enantiomers and Their Photophysics in Chiral Environments¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2005.tb01539.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Rahimipour S, Palivan C, Freeman D, Barbosa F, Fridkin M, Weiner L, Mazur Y, Gescheidt G. Hypericin Derivatives: Substituent Effects on Radical-anion Formation. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0740149hdseor2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Showalter BM, Datta A, Chowdhury PK, Park J, Bandyopadhyay P, Choudhury PK, Kesavan S, Zeng Y, Kraus GA, Gordon MS, Toscano JP, Petrich JW. Identification of a Vibrational Frequency Corresponding to H-atom Translocation in Hypericin¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0740157ioavfc2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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15
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Park J, Datta A, Chowdhury PK, Petrich JW. Is the Excited-State H-atom Transfer in Hypericin Concerted?¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2001)0730105itesha2.0.co2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Panda D, Khatua S, Datta A. Enhanced fluorescence of epicocconone in surfactant assemblies as a consequence of depth-dependent microviscosity. J Phys Chem B 2007; 111:1648-56. [PMID: 17263570 DOI: 10.1021/jp065226o] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The extents of fluorescence enhancement of epicocconone are found to be different in the micelles of the surfactants sodium dodecyl sulfate (SDS) and Triton X100 (TX 100). A decrease in fluorescence, observed in the cationic cetyltrimethylammonium bromide (CTAB) micelles, is rationalized by the formation of anions of the fluorophore at the Stern layer. To understand the difference in the effects of SDS and TX 100, the nature of the excited-state process in the fluorophore has been investigated by fluorescence spectroscopy, supported by complementary quantum chemical calculations. The excited-state dynamics of epicocconone is found to depend on polarity and viscosity of the medium, with a more pronounced dependence on viscosity. An inspection of the molecular orbitals involved in the electronic absorption of the molecule reveals the possibility of photoisomerization, which conforms to the observed solvent dependence of the fluorescence spectral properties. An apparent mismatch between trends observed in steady-state spectra and those in temporal decays indicates a significant contribution of an ultrafast component, which cannot be detected in the time resolution of our instrument. The viscosity dependence of the fluorescence quantum yields provides an explanation for the difference in the extents of fluorescence enhancement in the two micelles, in the light of location of the fluorophore at different depths of the micelle. The enhancement of fluorescence, with an unchanged fluorescence maximum, opens up the possibility that the fluorophore could be a useful dual emitting marker for fluorescence microscopy of heterogeneous systems, as the fluorescence of protein-bound epicocconone has been previously reported to be significantly red-shifted.
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Affiliation(s)
- Debashis Panda
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
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17
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Vogt G, Nuernberger P, Gerber G, Improta R, Santoro F. Femtosecond study on the isomerization dynamics of NK88. II. Excited-state dynamics. J Chem Phys 2006; 125:44513. [PMID: 16942162 DOI: 10.1063/1.2210939] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The molecule 3,3(')-diethyl-2,2(')-thiacyanine isomerizes after irradiation with light of the proper wavelength. After excitation, it undergoes a transition, in which one or more conical intersections are involved, back to the ground state to form different product photoisomers. The dynamics before and directly after the transition back to the ground state is investigated by transient absorption spectroscopy in a wavelength region of 360-950 nm, as well as by fluorescence upconversion. It is shown that the excited-state dynamics are governed by two time scales: a short one with a decay time of less than 2 ps and a long one with about 9 ps. A thorough comparison of the experimental results with those of configuration interaction singles and time-dependent density functional theory calculations suggests that these dynamics are related to two competing pathways differing in the molecular twisting on the excited surface after photoexcitation. From the experimental point of view this picture arises taking into account the time scales for ground-state bleach, excited-state absorption, stimulated emission, fluorescence, and assumed hot ground-state absorption both in the solvent methanol and ethylene glycol.
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Affiliation(s)
- Gerhard Vogt
- Physikalisches Institut, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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18
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Halder M, Headley LS, Mukherjee P, Song X, Petrich JW. Experimental and Theoretical Investigations of Solvation Dynamics of Ionic Fluids: Appropriateness of Dielectric Theory and the Role of DC Conductivity. J Phys Chem A 2006; 110:8623-6. [PMID: 16836422 DOI: 10.1021/jp062936l] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An analysis is provided of the subnanosecond dynamic solvation of ionic liquids in particular and ionic solutions in general. It is our hypothesis that solvation relaxation in ionic fluids, in the nonglassy and nonsupercooled regimes, can be understood rather simply in terms of the dielectric spectra of the solvent. This idea is suggested by the comparison of imidazolium ionic liquids with their pure organic counterpart, butylimidazole (J. Phys. Chem. B 2004, 108, 10245-10255). It is borne out by a calculation of the solvation correlation time from frequency dependent dielectric data for the ionic liquid, ethylammonium nitrate, and for the electrolyte solution of methanol and sodium perchlorate. Very good agreement is obtained between these theoretically calculated solvation relaxation functions and those obtained from fluorescence upconversion spectroscopy. Our comparisons suggest that translational motion of ions may not be the predominant factor in short-time solvation of ionic fluids and that many tools and ideas about solvation dynamics in polar solvents can be adapted to ionic fluids.
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Affiliation(s)
- M Halder
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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19
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Panda D, Mishra PP, Khatua S, Koner AL, Sunoj RB, Datta A. Anomalous Excited-State Dynamics of Lucifer Yellow CH in Solvents of High Polarity: Evidence for an Intramolecular Proton Transfer. J Phys Chem A 2006; 110:5585-91. [PMID: 16640350 DOI: 10.1021/jp056295q] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photophysics of the fluorescent probe Lucifer yellow CH has been investigated using fluorescence spectroscopic and computational techniques. The nonradiative rate is found to pass through a minimum in solvents of intermediate empirical polarity. This apparently anomalous behavior is rationalized by considering the possibility of predominance of different kinds of nonradiative processes, viz. intersystem crossing (ISC) and excited-state proton transfer (ESPT), in solvents of low and high empirical polarity, respectively. The feasibility of the proton transfer is examined by the structure determined by the density functional theory (DFT) calculations. The predicted energy levels based on the time-dependent density functional theory (TD-DFT) method in the gas phase identifies the energy gap between the S(1) and nearest triplet state to be close enough to facilitate ISC. Photophysical investigation in solvent mixtures and in deuterated solvents clearly indicates the predominance of the solvent-mediated intramolecular proton transfer in the excited state of the fluorophore in protic solvents.
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Affiliation(s)
- Debashis Panda
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, India
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20
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Yi PG, Liang YH. Theoretical studies of conjugation and substituent effect on intramolecular proton transfer in the ground and excited states. Chem Phys 2006. [DOI: 10.1016/j.chemphys.2005.09.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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21
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Webb SP. Ab initio electronic structure theory as an aid to understanding excited state hydrogen transfer in moderate to large systems. Theor Chem Acc 2005. [DOI: 10.1007/s00214-005-0011-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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22
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Halder M, Chowdhury PK, Das R, Mukherjee P, Atkins WM, Petrich JW. Interaction of Glutathione S-Transferase with Hypericin: A Photophysical Study. J Phys Chem B 2005; 109:19484-9. [PMID: 16853517 DOI: 10.1021/jp051645u] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The photophysics of hypericin have been studied in its complex with two different isoforms, A1-1 and P1-1, of the protein glutathione S-transferase (GST). One molecule of hypericin binds to each of the two GST subunits. Comparisons are made with our previous results for the hypericin/human serum albumin complex (Photochem. Photobiol. 1999, 69, 633-645). Hypericin binds with high affinity to the GSTs: 0.65 microM for the A1-1 isoform and 0.51 microM for the P1-1 isoform (Biochemistry 2004, 43, 12761-12769). The photophysics and activity of hypericin are strongly modulated by the binding protein. Intramolecular hydrogen-atom transfer is suppressed in both cases. Most importantly, while there is significant singlet oxygen generation from hypericin bound to GST A1-1, binding to GST P1-1 suppresses singlet oxygen generation to almost negligible levels. The data are rationalized in terms of a simple model in which the hypericin photophysics depends entirely upon the decay of the triplet state by two competing processes, quenching by oxygen to yield singlet oxygen and ionization, the latter of these two are proposed to be modulated by A1-1 and P1-1.
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Affiliation(s)
- M Halder
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
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23
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Plaza P, Mahet M, Tchaikovskaya ON, Martin MM. Excitation energy effect on the early photophysics of hypericin in solution. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.04.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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24
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Sanders L, Halder M, Xiao TL, Ding J, Armstrong DW, Petrich JW. The Separation of Hypericin's Enantiomers and Their Photophysics in Chiral Environments¶. Photochem Photobiol 2005. [DOI: 10.1562/2004-05-28-rn-181.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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Zhang LZ, Tang GQ, Gao BW, Zhang GL. Spectroscopic studies on the excited-state properties of the light-induced antiviral drug hypocrellin A loaded in the mesoporous solid. Chem Phys Lett 2004. [DOI: 10.1016/j.cplett.2004.07.124] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Chowdhury PK, Halder M, Sanders L, Calhoun T, Anderson JL, Armstrong DW, Song X, Petrich JW. Dynamic Solvation in Room-Temperature Ionic Liquids†. J Phys Chem B 2004. [DOI: 10.1021/jp0376828] [Citation(s) in RCA: 187] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Wang DP, Chen SG, Chen DZ. Theoretical studies of conjugate and substituent effects on the intramolecular proton transfer: an HF/CIS study. J Photochem Photobiol A Chem 2004. [DOI: 10.1016/s1010-6030(03)00382-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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28
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Wang DP, Chen SG, Chen DZ. Theoretical study on the trihydroxy-anthraquinone tautomerism in the ground and excited states. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s0166-1280(03)00529-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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29
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Xu S, Chen S, Zhang M, Shen T. First synthesis of methylated hypocrellin and its fluorescent excited state: a cautionary tale. J Org Chem 2003; 68:2048-50. [PMID: 12608836 DOI: 10.1021/jo026554x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methylated hypocrellins were obtained and characterized by satisfactory 1HNMR, UV-vis, IR, and mass data, and their absorption and fluorescence emission spectra were studied. A previous report of methylated hypocrellin (J. Phys. Chem. A 1999, 103, 7949) appears to be in error.
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Affiliation(s)
- Shangjie Xu
- Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China
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30
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Chowdhury P, Das K, Datta A, Liu WZ, Zhang HY, Petrich J. A comparison of the excited-state processes of nearly symmetrical perylene quinones: hypocrellin A and hypomycin B. J Photochem Photobiol A Chem 2002. [DOI: 10.1016/s1010-6030(02)00309-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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31
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Rahimipour S, Palivan C, Freeman D, Barbosa F, Fridkin M, Weiner L, Mazur Y, Gescheidt G. Hypericin derivatives: substituent effects on radical-anion formation. Photochem Photobiol 2001; 74:149-56. [PMID: 11547548 DOI: 10.1562/0031-8655(2001)074<0149:hdseor>2.0.co;2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The electron-transfer properties of the hypericin derivatives, dibromo-, hexaacetyl-, hexamethyl- and desmethylhypericin, were studied. Cyclovoltammetric measurements revealed that dibromo- and desmethylhypericin have almost the same redox potentials as the parent hypericin. Substitution of the hydroxyl groups by acetoxy leads to less negative E1/2 values, whereas methoxy substitution induces more negative values. Electron paramagnetic resonance (EPR)/electron nuclear double resonance/general TRIPLE spectroscopy and quantum mechanical calculations were used to establish the structure of the one-electron reduced stages of hypericin derivatives. Proton loss in the bay region, already demonstrated for hypericin, was also found for dibromo- and desmethylhypericin. The spin and charge of the radical ions are predominately confined to the central biphenoquinone moiety of the hypericin skeleton. Generation of the radical ions by in situ electrolysis indicates that the redox potentials of hypericin, dibromo- and desmethylhypericin, containing hydroxyls at the 1, 3, 4, 6, 8 and 13 positions, largely depend on the solvent. With phosphate-buffered saline (pH 7.4)/dimethylsulfoxide (DMSO) as the solvent the EPR spectra of the corresponding radical ions appear at markedly lower potentials than in pure DMSO and N,N'-dimethylformamide. However, this effect is not observable for hexaacetyl- and hexamethyl-hypericin-lacking hydroxyl groups. In all cases the EPR data and calculations revealed the presence of 7,14 tautomers.
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Affiliation(s)
- S Rahimipour
- Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel
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Showalter BM, Datta A, Chowdhury PK, Park J, Bandyopadhyay P, Choudhury PK, Kesavan S, Zeng Y, Kraus GA, Gordon MS, Toscano JP, Petrich JW. Identification of a vibrational frequency corresponding to H-atom translocation in hypericin. Photochem Photobiol 2001; 74:157-63. [PMID: 11547549 DOI: 10.1562/0031-8655(2001)074<0157:ioavfc>2.0.co;2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Using time-resolved infrared spectroscopy, ab initio quantum mechanical calculations and synthetic organic chemistry a region in the infrared spectrum of triplet hypericin has been found between 1400 and 1500 cm-1 corresponding to the translocation of the hydrogen atom between the enol and the keto oxygens, O...H...O. This result is discussed in the context of the photophysics of hypericin and of eventual measurements to observe directly the excited-state H-atom transfer.
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Affiliation(s)
- B M Showalter
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, USA
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Loerting T, Liedl KR. Water-Mediated Proton Transfer: A Mechanistic Investigation on the Example of the Hydration of Sulfur Oxides. J Phys Chem A 2001. [DOI: 10.1021/jp0038862] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The excited-state intramolecular H-atom transfer of hypericin (Hyp) was investigated as a function of pH in monodispersed reverse micelles formed by sodium bis(2-ethylhexyl)sulfosuccinate/heptane/water and in complexes with Tb3+ under conditions in which one of the two carbonyl groups of Hyp is incapable of accepting a hydrogen atom. The results of pump-probe transient absorption experiments provide no evidence for a concerted H-atom transfer mechanism.
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Affiliation(s)
- J Park
- Department of Chemistry, Iowa State University, Ames 50011, USA
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Datta A, Bandyopadhyay P, Wen J, Petrich JW, Gordon MS. Coupling of Large-Amplitude Side Chain Motions to the Excited-State H-Atom Transfer of Perylene Quinones: Application of Theory and Experiment to Calphostin C. J Phys Chem A 2001. [DOI: 10.1021/jp0035941] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Anindya Datta
- Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | | | - Jin Wen
- Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | - Jacob W. Petrich
- Department of Chemistry, Iowa State University, Ames, Iowa 50011
| | - Mark S. Gordon
- Department of Chemistry, Iowa State University, Ames, Iowa 50011
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