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Orange/Red Benzo[1,2- b:4,5- b']dithiophene 1,1,5,5-Tetraoxide-Based Emitters for Luminescent Solar Concentrators: Effect of Structures on Fluorescence Properties and Device Performances. ACS APPLIED ENERGY MATERIALS 2023; 6:4862-4880. [PMID: 37181248 PMCID: PMC10170478 DOI: 10.1021/acsaem.3c00362] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 04/11/2023] [Indexed: 05/16/2023]
Abstract
Luminescent solar concentrators (LSCs) are a class of optical devices able to harvest, downshift, and concentrate sunlight, thanks to the presence of emitting materials embedded in a polymer matrix. Use of LSCs in combination with silicon-based photovoltaic (PV) devices has been proposed as a viable strategy to enhance their ability to harvest diffuse light and facilitate their integration in the built environment. LSC performances can be improved by employing organic fluorophores with strong light absorption in the center of the solar spectrum and intense, red-shifted emission. In this work, we present the design, synthesis, characterization, and application in LSCs of a series of orange/red organic emitters featuring a benzo[1,2-b:4,5-b']dithiophene 1,1,5,5-tetraoxide central core as an acceptor (A) unit. The latter was connected to different donor (D) and acceptor (A') moieties by means of Pd-catalyzed direct arylation reactions, yielding compounds with either symmetric (D-A-D) or non-symmetric (D-A-A') structures. We found that upon light absorption, the compounds attained excited states with a strong intramolecular charge-transfer character, whose evolution was greatly influenced by the nature of the substituents. In general, symmetric structures showed better photophysical properties for the application in LSCs than their non-symmetric counterparts, and using a donor group of moderate strength such as triphenylamine was found preferable. The best LSC built with these compounds presented photonic (external quantum efficiency of 8.4 ± 0.1%) and PV (device efficiency of 0.94 ± 0.06%) performances close to the state-of-the-art, coupled with a sufficient stability in accelerated aging tests.
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Triterpene Derivatives as Potential Inhibitors of the RBD Spike Protein from SARS-CoV-2: An In Silico Approach. Molecules 2023; 28:molecules28052333. [PMID: 36903578 PMCID: PMC10005606 DOI: 10.3390/molecules28052333] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/26/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
The appearance of a new coronavirus, SARS-CoV-2, in 2019 kicked off an international public health emergency. Although rapid progress in vaccination has reduced the number of deaths, the development of alternative treatments to overcome the disease is still necessary. It is known that the infection begins with the interaction of the spike glycoprotein (at the virus surface) and the angiotensin-converting enzyme 2 cell receptor (ACE2). Therefore, a straightforward solution for promoting virus inhibition seems to be the search for molecules capable of abolishing such attachment. In this work, we tested 18 triterpene derivatives as potential inhibitors of SARS-CoV-2 against the receptor-binding domain (RBD) of the spike protein by means of molecular docking and molecular dynamics simulations, modeling the RBD S1 subunit from the X-ray structure of the RBD-ACE2 complex (PDB ID: 6M0J). Molecular docking revealed that at least three triterpene derivatives of each type (i.e., oleanolic, moronic and ursolic) present similar interaction energies as the reference molecule, i.e., glycyrrhizic acid. Molecular dynamics suggest that two compounds from oleanolic and ursolic acid, OA5 and UA2, can induce conformational changes capable of disrupting the RBD-ACE2 interaction. Finally, physicochemical and pharmacokinetic properties simulations revealed favorable biological activity as antivirals.
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Electronic structure and interfacial features of triphenylamine- and phenothiazine-based hole transport materials for methylammonium lead iodide perovskite solar cells. Phys Chem Chem Phys 2022; 24:14993-15002. [DOI: 10.1039/d2cp01270g] [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
Recently, great research efforts have been devoted to perovskite solar cells (PSCs) leading to sunlight-to-power conversion efficiencies above 25%. However, several barriers still hinder the full deployment of these devices....
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The critical issue of using lead for sustainable massive production of perovskite solar cells: a review of relevant literature. OPEN RESEARCH EUROPE 2021; 1:44. [PMID: 37645134 PMCID: PMC10445902 DOI: 10.12688/openreseurope.13428.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/18/2021] [Indexed: 08/31/2023]
Abstract
This work aims to review the most significant studies dealing with the environmental issues of the use of lead in perovskite solar cells (PSCs). A careful discussion and rationalization of the environmental and human health toxicity impacts, evaluated by life cycle assessment and risk assessment studies, is presented. The results of this analysis are prospectively related to the possible future massive production of PSC technology.
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The β-hairpin from the Thermus thermophilus HB27 laccase works as a pH-dependent switch to regulate laccase activity. J Struct Biol 2021; 213:107740. [PMID: 33962016 DOI: 10.1016/j.jsb.2021.107740] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 04/30/2021] [Accepted: 04/30/2021] [Indexed: 11/29/2022]
Abstract
The multi-copper oxidase from the hyper-thermophilic bacteria Thermus thermophilus (Tth-MCO), has been previously characterized and described as an example of a laccase with low catalytic properties, especially when it is compared with the activity of fungal laccases, but it is active at high temperatures. Structurally, Tth-MCO has a unique feature: a β-hairpin near the T1Cu site, which is not present in any other laccases deposited at the PDB. This β-hairpin has an expected crystallographic behavior in solvent-exposed areas of a crystallized protein: lack of electron density, high B-values and several crystalline contacts with neighboring crystallographic copies; however, its dynamical behavior in solution and its biological implications have not been described. Here, we describe four new Tth-MCO crystallographic structures, and the β-hairpin behavior has been analyzed by molecular dynamics simulations, considering the effect of pH and temperature. The β-hairpin new crystallographic conformations described here, together with their dynamics, were used to understand the pH-restrained laccase activity of Tth-MCO against substrates as syringaldazine. Remarkably, there are insertions in laccases from Thermus and Meiothermus genus, sharing the same position and a methionine-rich composition of the Tth-MCO β-hairpin. This unique high methionine content of the Tth-MCO β-hairpin is responsible to coordinate, Ag+1 and Hg+1 in oxidative conditions, but Cu+1 and Cu+2 are not coordinated in crystallographic experiments, regardless of the redox conditions; however, Ag+1 addition does not affect Tth-MCO laccase activity against syringaldazine. Here, we propose that the pH-dependent β-hairpin dynamical behavior could explain, at least in part, the inefficient laccase activity displayed by Tth-MCO in acidic pH values.
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In silico investigation of catechol-based sensitizers for type II dye sensitized solar cells (DSSCs). Inorganica Chim Acta 2021. [DOI: 10.1016/j.ica.2020.120233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Environmental and economic optima of solar home systems design: A combined LCA and LCC approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 744:140569. [PMID: 32687999 DOI: 10.1016/j.scitotenv.2020.140569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 05/31/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
This paper compares the economic and environmental optimal design of Solar Home Systems (SHSs) and explores the role of economic incentives (such as tariffs and technology costs) in approximating the two optima. To achieve that, we present a methodology for the environmental and economic evaluation of grid-connected SHSs: user-scale electric systems involving a photovoltaic (PV) power system and a battery energy storage system. The proposed methodology is based on a mixed integer linear programming (MILP) optimization, life cycle assessment and life cycle costing. This methodological framework is applied to a case study involving a typical SHS installation in Italy. The results of the environmental optimal design brought to the evaluation of a 3.25 kW PV assisted by 8.66 kWh of nickel cobalt manganese batteries, whereas the costs of the SHS are minimized by a small PV system (less than 1 kW). Results underline that the environmental optimal configurations rely on battery technologies, which entails a significant cost compared to the grid connection. In contrast, the economic optimal design solutions is less impactful than the grid mix both from an environmental and economic points of view. Thanks to a reduction of batteries and PV costs, the environmental impact of the economic optimal design is expected to decrease in the future.
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Synthesis and Characterization of New Organic Dyes Containing the Indigo Core. Molecules 2020; 25:E3377. [PMID: 32722406 PMCID: PMC7435895 DOI: 10.3390/molecules25153377] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/17/2020] [Accepted: 07/21/2020] [Indexed: 11/16/2022] Open
Abstract
A new series of symmetrical organic dyes containing an indigo central core decorated with different electron donor groups have been prepared, starting from Tyrian Purple and using the Pd-catalyzed Stille-Migita coupling process. The effect of substituents on the spectroscopic properties of the dyes has been investigated theoretically and experimentally. In general, all dyes presented intense light absorption bands, both in the blue and red regions of the visible spectrum, conferring them a bright green color in solution. Using the same approach, an asymmetrically substituted D-A-π-A green dye, bearing a triarylamine electron donor and the cyanoacrylate acceptor/anchoring group, has been synthesized for the first time and fully characterized, confirming that spectroscopic and electrochemical properties are consistent with a possible application in dye-sensitized solar cells (DSSC).
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Combined LCA and Green Metrics Approach for the Sustainability Assessment of an Organic Dye Synthesis on Lab Scale. Front Chem 2020; 8:214. [PMID: 32296679 PMCID: PMC7136579 DOI: 10.3389/fchem.2020.00214] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 03/09/2020] [Indexed: 11/30/2022] Open
Abstract
New generation photovoltaic devices have attracted much attention in the last decades since they can be efficiently manufactured employing abundant raw materials and with less-energy intensive processes. In this context, the use of powerful environmental assessment is pivotal to support the fine-tuning of solar cells fabrication and hit the target of manufacturing effective sustainable technological devices. In this work, a mass-based green metrics and life cycle assessment combined approach is applied to analyze the environmental performances of an innovative synthetic protocol for the preparation of organic dye TTZ5, which has been successfully proposed as sensitizer for manufacturing dye sensitized solar cells. The new synthetic strategy, which is based on the C-H activation process, has been compared with the previously reported synthesis employing classic Suzuki-Miyaura cross-coupling chemistry. Results highlight the contribution of direct energy consumption and purification operations in organic syntheses at lab scale. Furthermore, they demonstrate the usefulness of the environmental multifaceted analytic tool and the power of life cycle assessment to overcome the intrinsic less comprehensive nature of green metrics for the evaluation of organic synthetic protocols.
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Environmental analysis of a nano-grid: A Life Cycle Assessment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 700:134814. [PMID: 31693959 DOI: 10.1016/j.scitotenv.2019.134814] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 09/04/2019] [Accepted: 10/02/2019] [Indexed: 06/10/2023]
Abstract
Renewable energy sources are fundamental to face the problem of climate changes. Unfortunately, some resources, such as wind and solar radiation, have fluctuations affecting the electrical grids stability. Energy storage systems can be used for a smart energy management to accumulate power from renewable sources. For such reason, these devices play a key role to achieve a sustainable electric system. On the other hand, they are affected by some environmental drawbacks mainly connected with the depletion of rare and expensive materials. Based on these considerations, in this study a nano-grid composed by a photovoltaic plant, a backup generator and an energy storage system is analysed by an environmental Life Cycle Assessment approach. A Solar Home System is designed, and its environmental profile is evaluated considering several Lithium-ion batteries. Among them, nickel-cobalt aluminium oxide cells resulted to be the most suitable solution for a Solar Home System (46.66 Pts/MWh). Moreover, a sensitivity analysis of the Solar Home System is performed and a hybrid energy storage plant integrating hydrogen and batteries is proposed to face the problem of seasonal solar radiation variability. Four scenarios having different gas pressure levels and lifespan of the devices are considered. Results show that currently the most sustainable configuration is represented by the Solar Home System, but in the future a hybrid nano-grid equipped with 700 bar hydrogen storage might be the best off-grid configuration for minimizing the impact on the environment (37.77 Pts/MWh). Extending the perspective of our analysis to future on-grid potential configurations, an efficient connection of the Solar Home System with a smart-grid is assessed as it looks more sustainable than other off-grid solutions (22.81 Pts/MWh).
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Design, synthesis, structure, and photophysical features of highly emissive cinnamic derivatives. NEW J CHEM 2020. [DOI: 10.1039/d0nj02429e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New cinnamic derivatives 1a–c were designed starting from the chromophores working in polybenzofulvene derivatives poly-6-DMFL-BF3k, poly-6-MCBZ-BF3k, and poly-6-TPA-BF3k endowed with outstanding optoelectronic performances.
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Life Cycle Inventory datasets for nano-grid configurations. Data Brief 2019; 28:104895. [PMID: 31872010 PMCID: PMC6911934 DOI: 10.1016/j.dib.2019.104895] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 11/24/2022] Open
Abstract
Datasets concerning some user-scale Smart Grids, named Nano-grids, are reported in this paper. First several Solar Home Systems composed of a photovoltaic plant, a backup generator and different types of lithium-ion batteries are provided. Then, the inventory analysis of hybrid Nano-grids integrating batteries and hydrogen storage is outlined according to different scenarios. These data inventory could be useful for any academic or stakeholder interested in reproducing this analysis and/or developing environmental sustainability assessment in the field of Smart Grids. For more insight, please see "Environmental analysis of a Nano-Grid: a Life Cycle Assessment" by Rossi F, Parisi M.L., Maranghi S., Basosi R., Sinicropi A. [1].
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Fibrils of α-Synuclein Abolish the Affinity of Cu2+-Binding Site to His50 and Induce Hopping of Cu2+ Ions in the Termini. Inorg Chem 2019; 58:10920-10927. [DOI: 10.1021/acs.inorgchem.9b01337] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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New Blue Donor-Acceptor Pechmann Dyes: Synthesis, Spectroscopic, Electrochemical, and Computational Studies. ACS OMEGA 2019; 4:7614-7627. [PMID: 31459854 PMCID: PMC6648098 DOI: 10.1021/acsomega.8b03560] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 02/14/2019] [Indexed: 06/10/2023]
Abstract
The design, synthesis, and characterization of a new class of blue-colored thiophene-substituted Pechmann dyes are reported. Due to a distinguishing blue coloration and the capability to absorb light in one of the most photon-dense regions of the solar spectrum, such compounds are of great interest for application as photoactive materials in organic optoelectronics, in particular, in dye-sensitized solar cells. To achieve fine tuning of the optical and electrochemical properties, the electron-poor thiophene-bis-lactone moiety has been decorated with donor (D) and acceptor groups (A), targeting fully conjugated D-A-π-A structures. The designed structures have been investigated by means of DFT and time-dependent DFT calculations, and the most promising dyes have been synthesized. These molecules represent the very first preparation of unsymmetrical Pechmann derivatives. Optical and electrochemical properties of the new dyes have been studied by cyclic voltammetry and UV-vis and fluorescence spectroscopy. In two cases, test cells were built proving that a photocurrent can indeed be generated when using electrolytes especially formulated for narrow-band-gap dyes, although with a very low efficiency.
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Tailoring the Optical Properties of Organic D‐π‐A Photosensitizers: Effect of Sulfur Introduction in the Acceptor Group. European J Org Chem 2018. [DOI: 10.1002/ejoc.201801497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Photoinduced excitation and charge transfer processes of organic dyes with siloxane anchoring groups: a combined spectroscopic and computational study. Phys Chem Chem Phys 2018; 19:15310-15323. [PMID: 28569917 DOI: 10.1039/c7cp01956d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dye-sensitized solar cells (DSSCs) have attracted significant interest in the last few years as effective low-cost devices for solar energy conversion. We have analyzed the excited state dynamics of several organic dyes bearing both cyanoacrylic acid and siloxane anchoring groups. The spectroscopic properties of the dyes have been studied both in solution and when adsorbed on a TiO2 film using stationary and time-resolved techniques, probing the sub-picosecond to nanosecond time interval. The comparison between the spectra registered in solution and on the solid substrate evidences different pathways for energy and electron relaxation. The transient spectra of the TiO2-adsorbed dyes show the appearance of a long wavelength excited state absorption band, attributed to the cationic dye species, which is absent in the spectra measured in solution. Furthermore, the kinetic traces of the samples adsorbed on the TiO2 film show a long decay component not present in solution which constitutes indirect evidence of electron transfer between the dye and the semiconductor. The interpretation of the experimental results has been supported by theoretical DFT calculations of the excited state energies and by the analysis of molecular orbitals of the analyzed dye molecules.
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DFT modeling of structures and redox potentials of wild-type, Nickel-substituted and mutated (N47S/M121L, HPAz) Azurin. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.08.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Synthesis of Silatrane-Containing Organic Sensitizers as Precursors for the Silyloxyl Anchoring Group in Dye-Sensitized Solar Cells. SYNTHESIS-STUTTGART 2017. [DOI: 10.1055/s-0036-1588836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
A series of organic D-π-A dyes, endowed with different silicon-based anchoring groups, has been prepared to assess the stability of such anchoring moieties on nanocrystalline TiO2 in dye-sensitized solar cells. Due to the difficulties encountered in finding a reliable and robust preparation protocol to obtain pure trialkoxysilanes, replacement with a silatrane moiety was evaluated. It was found that the silatrane group could be easily introduced on three different molecular scaffolds by using a simple amide coupling reaction mediated by EDC-Cl. Furthermore, the spectroscopic properties and anchoring mode on nanocrystalline TiO2 of the silatrane dyes were found to be nearly identical to those of the trialkoxysilane compounds, and both gave a much more stable attachment to the semiconductor compared with their cyanoacrylic acid counterpart, as shown by desorption experiments.
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Tyrosine or Tryptophan? Modifying a Metalloradical Catalytic Site by Removal of the Cys-Tyr Cross-Link in the Galactose 6-Oxidase Homologue GlxA. Angew Chem Int Ed Engl 2017; 56:6502-6506. [DOI: 10.1002/anie.201701270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 03/13/2017] [Indexed: 11/10/2022]
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Tyrosine or Tryptophan? Modifying a Metalloradical Catalytic Site by Removal of the Cys-Tyr Cross-Link in the Galactose 6-Oxidase Homologue GlxA. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201701270] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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22
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Synthesis and Investigation of Solar-Cell Photosensitizers Having a Fluorazone Backbone. European J Org Chem 2017. [DOI: 10.1002/ejoc.201601622] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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23
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Two New Dyes with Carboxypyridinium Regioisomers as Anchoring Groups for Dye-Sensitized Solar Cells. Synlett 2015. [DOI: 10.1055/s-0035-1560713] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Chromophore–Protein Coupling beyond Nonpolarizable Models: Understanding Absorption in Green Fluorescent Protein. J Chem Theory Comput 2015; 11:4825-39. [DOI: 10.1021/acs.jctc.5b00650] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Redox-Active Sites in Auricularia auricula-judae Dye-Decolorizing Peroxidase and Several Directed Variants: A Multifrequency EPR Study. J Phys Chem B 2015; 119:13583-92. [PMID: 26120933 DOI: 10.1021/acs.jpcb.5b02961] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peroxide-activated Auricularia auricula-judae dye-decolorizing peroxidase (DyP) forms a mixed Trp377 and Tyr337 radical, the former being responsible for oxidation of the typical DyP substrates (Linde et al. Biochem. J., 2015, 466, 253-262); however, a pure tryptophanyl radical EPR signal is detected at pH 7 (where the enzyme is inactive), in contrast with the mixed signal observed at pH for optimum activity, pH 3. On the contrary, the presence of a second tyrosine radical (at Tyr147) is deduced by a multifrequency EPR study of a variety of simple and double-directed variants (including substitution of the above and other tryptophan and tyrosine residues) at different freezing times after their activation by H2O2 (at pH 3). This points out that subsidiary long-range electron-transfer pathways enter into operation when the main pathway(s) is removed by directed mutagenesis, with catalytic efficiencies progressively decreasing. Finally, self-reduction of the Trp377 neutral radical is observed when reaction time (before freezing) is increased in the absence of reducing substrates (from 10 to 60 s). Interestingly, the tryptophanyl radical is stable in the Y147S/Y337S variant, indicating that these two tyrosine residues are involved in the self-reduction reaction.
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Spectroscopic and computational characterization of laccases and their substrate radical intermediates. Cell Mol Life Sci 2015; 72:885-96. [PMID: 25595303 PMCID: PMC11113710 DOI: 10.1007/s00018-014-1825-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 12/30/2014] [Indexed: 11/28/2022]
Abstract
Laccases are multicopper oxidases which oxidize a wide variety of aromatic compounds with the concomitant reduction of oxygen to water as by-product. Due to their high stability and biochemical versatility, laccases are key enzymes to be used as eco-friendly biocatalyst in biotechnological applications. The presence of copper paramagnetic species in the catalytic site paired with the substrate radical species produced in the catalytic cycle makes laccases particularly attractive to be studied by spectroscopic approaches. In this review, the potentiality of a combined multifrequency electron paramagnetic spectroscopy /computational approach to gain information on the nature of the catalytic site and radical species is presented. The knowledge at molecular level of the enzyme oxidative process can be of great help to model new enzymes with increased efficiency and robustness.
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Thiazolo[5,4-d]thiazole-based organic sensitizers with strong visible light absorption for transparent, efficient and stable dye-sensitized solar cells. RSC Adv 2015. [DOI: 10.1039/c5ra03530a] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Five thiazolothiazole-based dyes, bearing electronrich ProDOT groups, were used as sensitizers in thin-layer DSSCs (active area: 0.25–3.6 cm2; TiO2 thickness: 3.0–6.5 μm), giving efficiencies up to 7.71% coupled with excellent stability over 1000 h.
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Organic dyes with intense light absorption especially suitable for application in thin-layer dye-sensitized solar cells. Chem Commun (Camb) 2014; 50:13952-5. [DOI: 10.1039/c4cc06160h] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Excited State Geometries and Vertical Emission Energies of Solvated Dyes for DSSC: A PCM/TD-DFT Benchmark Study. J Chem Theory Comput 2014; 10:3925-33. [DOI: 10.1021/ct500328t] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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In silico spectroscopy of tryptophan and tyrosine radicals involved in the long-range electron transfer of cytochrome c peroxidase. J Phys Chem B 2014; 118:9525-37. [PMID: 25084495 DOI: 10.1021/jp5025153] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytochrome c peroxidase (CcP) is a heme-containing enzyme that catalyzes the oxidation of the ferrocytochrome c to ferricytochrome c with concomitant reduction of H2O2 to H2O. Its catalytic cycle involves the formation of a double oxidized species (compound I) consisting of an oxoferryl center (Fe(IV)═O) and an amino acid radical (R(•)). Here we use a quantum-mechanics/molecular-mechanics (QM/MM) computational protocol based on density functional theory (DFT) and multiconfigurational perturbation theory (CASPT2) methods to reproduce specific features of compound I EPR and UV-vis spectra. The results show that the employed QM/MM models can correctly predict the magnetic, electronic and vibrational properties of the observed amino acid radicals of compound I. Furthermore, we have been able to confirm that the principal radical species of compound I is a tryptophan cationic radical located on residue 191 (Trp191(•+)) and that three tyrosine residues (Tyr203, Tyr236, and Tyr251), located along two possible ET pathways involving Trp191(•+), are possible candidates to host the secondary radical species.
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Organic Chromophores Based on a Fused Bis-Thiazole Core and Their Application in Dye-Sensitized Solar Cells. European J Org Chem 2013. [DOI: 10.1002/ejoc.201301094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Prediction of hydrogen-bonding networks around tyrosyl radical inP. eryngiiversatile peroxidase W164Y variants: a QM/MM MD study. MOLECULAR SIMULATION 2013. [DOI: 10.1080/08927022.2013.822967] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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33
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Effects of the Protein Environment on the Spectral Properties of Tryptophan Radicals in Pseudomonas aeruginosa Azurin. J Am Chem Soc 2013; 135:4822-33. [DOI: 10.1021/ja400464n] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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35
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Organic Chromophores Based on a Fused Bis-Thiazole Core and Their Application in Dye-Sensitized Solar Cells. European J Org Chem 2013. [DOI: 10.1002/ejoc.201201629] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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36
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The nature of tryptophan radicals involved in the long-range electron transfer of lignin peroxidase and lignin peroxidase-like systems: Insights from quantum mechanical/molecular mechanics simulations. Proteins 2012; 80:1476-83. [DOI: 10.1002/prot.24046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 01/18/2012] [Accepted: 01/25/2012] [Indexed: 01/21/2023]
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37
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Bathochromic Shift in Green Fluorescent Protein: A Puzzle for QM/MM Approaches. J Chem Theory Comput 2011; 8:112-24. [PMID: 26592874 DOI: 10.1021/ct200704k] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present an extensive investigation of the vertical excitations of the anionic and neutral forms of wild-type green fluorescent protein using time-dependent density functional theory (TDDFT), multiconfigurational perturbation theory (CASPT2), and quantum Monte Carlo (QMC) methods within a quantum mechanics/molecular mechanics (QM/MM) scheme. The protein models are constructed via room-temperature QM/MM molecular dynamics simulations based on DFT and are representative of an average configuration of the chromophore-protein complex. We thoroughly verify the reliability of our structures through simulations with an extended QM region, different nonpolarizable force fields, as well as partial reoptimization with the CASPT2 approach. When computing the excitations, we find that wave function as well as density functional theory methods with long-range corrected functionals agree in the gas phase with the extrapolation of solution experiments but fail in reproducing the bathochromic shift in the protein, which should be particularly significant in the neutral case. In particular, while all methods correctly predict a shift in the absorption between the anionic and neutral forms of the protein, the location of the theoretical absorption maxima is significantly blue-shifted and too close to the gas-phase values. These results point to either an intrinsic limitation of nonpolarizable force-field embedding in the computation of the excitations or to the need to explore alternative protonation states of amino acids in the close vicinity of the chomophore.
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Insights into the homocoupling reaction of 4-methylamino benzoic acid mediated by Trametes versicolor laccase. MOLECULAR BIOSYSTEMS 2011; 7:2967-9. [PMID: 21912806 DOI: 10.1039/c1mb05301a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spectroscopic measurements combined with Density Functional Theory calculations were applied to the characterization of the homocoupling reaction of 4-methylamino benzoic acid mediated by laccase.
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EPR parameters of amino acid radicals in P. eryngii versatile peroxidase and its W164Y variant computed at the QM/MM level. Phys Chem Chem Phys 2011; 13:5078-98. [DOI: 10.1039/c0cp02151b] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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40
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Modeling, preparation, and characterization of a dipole moment switch driven by Z/E photoisomerization. J Am Chem Soc 2010; 132:9310-9. [PMID: 20568762 DOI: 10.1021/ja906733q] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the results of a multidisciplinary research effort where the methods of computational photochemistry and retrosynthetic analysis/synthesis have contributed to the preparation of a novel N-alkylated indanylidene-pyrroline Schiff base featuring an exocyclic double bond and a permanent zwitterionic head. We show that, due to its large dipole moment and efficient photoisomerization, such a system may constitute the prototype of a novel generation of electrostatic switches achieving a reversible light-induced dipole moment change on the order of 30 D. The modeling of a peptide fragment incorporating the zwitterionic head into a conformationally rigid side chain shows that the switch can effectively modulate the fluorescence of a tryptophan probe.
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Modeling the Fluorescence of Protein-Embedded Tryptophans with ab Initio Multiconfigurational Quantum Chemistry: The Limiting Cases of Parvalbumin and Monellin. J Phys Chem B 2009; 113:16082-90. [DOI: 10.1021/jp9080993] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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42
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Evidence for a radical mechanism in biocatalytic degradation of synthetic dyes by fungal laccases mediated by violuric acid. BIOCATAL BIOTRANSFOR 2009. [DOI: 10.1080/10242420701422757] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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43
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A novel biomimetic photochemical switch at work: design of a photomodulable peptide. Photochem Photobiol Sci 2009; 8:1639-49. [DOI: 10.1039/b906271h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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44
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An artificial molecular switch that mimics the visual pigment and completes its photocycle in picoseconds. Proc Natl Acad Sci U S A 2008; 105:17642-7. [PMID: 19004797 PMCID: PMC2584735 DOI: 10.1073/pnas.0802376105] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Indexed: 11/18/2022] Open
Abstract
Single molecules that act as light-energy transducers (e.g., converting the energy of a photon into atomic-level mechanical motion) are examples of minimal molecular devices. Here, we focus on a molecular switch designed by merging a conformationally locked diarylidene skeleton with a retinal-like Schiff base and capable of mimicking, in solution, different aspects of the transduction of the visual pigment Rhodopsin. Complementary ab initio multiconfigurational quantum chemistry-based computations and time-resolved spectroscopy are used to follow the light-induced isomerization of the switch in methanol. The results show that, similar to rhodopsin, the isomerization occurs on a 0.3-ps time scale and is followed by <10-ps cooling and solvation. The entire (2-photon-powered) switch cycle was traced by following the evolution of its infrared spectrum. These measurements indicate that a full cycle can be completed within 20 ps.
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Characterization of radical intermediates in laccase-mediator systems. A multifrequency EPR, ENDOR and DFT/PCM investigation. Phys Chem Chem Phys 2008; 10:7284-92. [PMID: 19060974 DOI: 10.1039/b812096j] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Suitable low molecular-weight compounds, called mediators, can be used in combination with the phenol-oxidase enzyme laccase to indirectly oxidize large organic substrates, such as environmental pollutants, which are not laccase natural substrates. The oxidation of two different synthetic redox mediators, violuric acid (VIO) and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) has been studied under catalysis of two laccases from white-rot fungi (Trametes versicolor and Pleurotus ostreatus). VIO was selected as a prototype of the -NOH type of mediators and compared to ABTS, a well-known two-step redox system. To characterize the radical intermediates formed from both mediators after the enzymatic oxidation, a multifrequency EPR approach has been adopted. The radical species have been investigated employing 9.4 GHz (X-band), 34 GHz (Q-band) and 244 GHz (high field) EPR and pulse electron nuclear double resonance (ENDOR) techniques. Theoretical calculations based on density functional theory (DFT/PCM) have been performed to support and further interpret the experimental EPR and ENDOR data. This integrated approach allowed us to obtain a complete characterization of both radicals and to elucidate the type of the radical state (neutral or cationic).
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46
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Recent applications of a QM/MM scheme at the CASPT2//CASSCF/AMBER (or CHARMM) level of theory in photochemistry and photobiology. ACTA ACUST UNITED AC 2008. [DOI: 10.1088/1742-6596/101/1/012001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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47
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The cis/trans isomerization of Cu(II)-bis-(glycinato) complex in solution: a computer aided multifrequency EPR and DFT/PCM calculation study. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45:846-9. [PMID: 17691070 DOI: 10.1002/mrc.2057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In this paper the Cu(II)-bis-(glycinato) complex has been analysed in solution by applying a combined approach of multifrequency EPR and DFT/PCM calculations. The accuracy in the determination of magnetic parameters has been reached by the use of a unique simulation program (COSMOS) for the whole range of temperatures analysed and by the error analysis. A change in magnetic parameters was envisaged in the 243-253 K range of temperature, and was interpreted in terms of stabilization, near the freezing point of the solution, of one of the isomers of the complex. A DFT/PCM computational model was crucial in assigning, on the basis of the experimental superhyperfine interaction value, the isomer to the trans form.
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48
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Characterization of the conical intersection of the visual pigment rhodopsin at the CASPT2//CASSCF/AMBER level of theory. Mol Phys 2007. [DOI: 10.1080/00268970500415865] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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49
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50
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Quantum Chemical Modeling and Preparation of a Biomimetic Photochemical Switch. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200602915] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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