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Ramos ML, Justino LLG, Barata R, Costa T, Burrows HD. Complexes of In(III) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and the effect of cationic surfactants on the photophysical behaviour. Dalton Trans 2021; 50:16970-16983. [PMID: 34752595 DOI: 10.1039/d1dt02858h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Following previous studies on the complexation in aqueous solutions of 8-hydroxyquinoline-5-sulfonate (8-HQS) with the trivalent metal ions, Al(III) and Ga(III) and various other metal ions, using multinuclear NMR, DFT calculations, UV-vis absorption and luminescence techniques, we have extended our studies on 8-HQS complexation to the trivalent metal ion In(III). The study combines the high sensitivity of luminescence techniques and the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a complete understanding of the complexation between the In3+ metal ion and 8-HQS, and how this influences the luminescence behaviour. A full speciation study has been performed and, as has been reported for the complexes of 8-hydroxyquinoline (8-HQ), the dominant complexes of 8-HQS with In(III) show marked differences in the complexation behaviour when compared with the equivalent complexes with the other group 13 cations Al(III) and Ga(III). While all three complexes have a 1 : 3 (metal : ligand) stoichiometry, those with Al(III) and Ga(III) show a mer-geometry of the ligands around the metal centre, whereas the fac-geometry is observed for the complexes with In(III). On binding to metal ions, 8-HQS shows a marked increase in the intensity of the fluorescence emission band compared to that of the virtually non-luminescent free ligand. However, the increase for In(III) is less pronounced than with Al(III) or Ga(III). These observations have important implications for the application of the complexes in sensing, light emitting devices (e.g. OLEDs), or as electron transport layers in photovoltaics for solar energy conversion. Furthermore, surfactant complexation is known to improve the fluorescence intensity in metal complexes with 8-HQS, by inhibiting the ligand exchange, as we have reported for complexes of HQS with Al(III) and Ga(III). Accordingly, in view of the development of applications in either sensing or optoelectronics, our interest also includes the study of HQS complexes of In(III) in the presence of cationic surfactants, in comparison with previous results with Al(III) and Ga(III).
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Affiliation(s)
- M Luísa Ramos
- Chemistry Department and Coimbra Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Licínia L G Justino
- Chemistry Department and Coimbra Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Rui Barata
- Chemistry Department and Coimbra Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Telma Costa
- Chemistry Department and Coimbra Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Hugh D Burrows
- Chemistry Department and Coimbra Chemistry Centre, University of Coimbra, 3004-535 Coimbra, Portugal.
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Fernandes SS, Castro MCR, Pereira AI, Mendes A, Serpa C, Pina J, Justino LLG, Burrows HD, Raposo MMM. Optical and Photovoltaic Properties of Thieno[3,2- b]thiophene-Based Push-Pull Organic Dyes with Different Anchoring Groups for Dye-Sensitized Solar Cells. ACS Omega 2017; 2:9268-9279. [PMID: 29302638 PMCID: PMC5748282 DOI: 10.1021/acsomega.7b01195] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 12/04/2017] [Indexed: 05/24/2023]
Abstract
The effect of anchoring groups on the optical and electrochemical properties of triphenylamine-thienothiophenes, and on the photovoltaic performance of DSSCs photosensitized with the prepared dyes, was studied using newly synthesized compounds with cyanoacetic acid or rhodanine-3-acetic acid groups. Precursor aldehydes were synthesized through Suzuki cross-coupling, whereas Knoevenagel condensation of these with 2-cyanoacetic acid or rhodanine-3-acetic acid afforded the final push-pull dyes. A comprehensive photophysical study was performed in solution and in the solid state. The femtosecond time-resolved transient absorption spectra for the synthesized dyes were obtained following photoexcitation in solution and for the dyes adsorbed to TiO2 mesoporous films. Information on conformation, electronic structure, and electron distribution was obtained by density functional theory (DFT) and time-dependent DFT calculations. Triphenylamine-thienothiophene functionalized with a cyanoacetic acid anchoring group displayed the highest conversion efficiency (3.68%) as the dye sensitizer in nanocrystalline TiO2 solar cells. Coadsorption studies were performed for this dye with the ruthenium-based N719 dye, and they showed dye power conversion efficiencies enhanced by 20-64%. The best cell performance obtained with the coadsorbed N719 and cyanoacetic dye showed an efficiency of 6.05%.
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Affiliation(s)
- Sara S.
M. Fernandes
- Centro
de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - M. Cidália R. Castro
- Centro
de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - Ana Isabel Pereira
- LEPABE—Faculdade
de Engenharia, Universidade do Porto, rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Adélio Mendes
- LEPABE—Faculdade
de Engenharia, Universidade do Porto, rua Dr. Roberto Frias, 4200-465 Porto, Portugal
| | - Carlos Serpa
- Centro
de Química de Coimbra, Departamento de Química, Universidade de Coimbra, P3004-535 Coimbra, Portugal
| | - João Pina
- Centro
de Química de Coimbra, Departamento de Química, Universidade de Coimbra, P3004-535 Coimbra, Portugal
| | - Licínia L. G. Justino
- Centro
de Química de Coimbra, Departamento de Química, Universidade de Coimbra, P3004-535 Coimbra, Portugal
| | - Hugh D. Burrows
- Centro
de Química de Coimbra, Departamento de Química, Universidade de Coimbra, P3004-535 Coimbra, Portugal
| | - M. Manuela M. Raposo
- Centro
de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Ramos ML, Justino LLG, Barata R, Costa T, Nogueira BA, Fausto R, Burrows HD. Oxocomplexes of U(vi) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and photophysical behaviour. Dalton Trans 2017; 46:9358-9368. [PMID: 28548670 DOI: 10.1039/c7dt01324h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multinuclear (1H and 13C) NMR, and Raman spectroscopy, combined with DFT calculations, provide detailed information on the complexation between U(vi) oxoions and 8-hydroxyquinoline-5-sulfonate (8-HQS) in aqueous solution. Over the concentration region studied, U(vi) oxoions (uranyl ions) form one dominant complex with 8-HQS in water in the pH range 3-6, a mononuclear 1 : 2 (metal : ligand) complex, with the metal centre (UO22+) coordinated to two 8-HQS ligands, together with one or more water molecules. An additional minor 1 : 1 complex has also been detected for solutions with a 1 : 1 metal : ligand molar ratio. The geometry of the dominant complex is proposed based on the combination of the NMR and Raman results with DFT calculations. Further information on the electronic structure of the complex has been obtained from UV/visible absorption and luminescence spectra. The complex of U(vi) and 8-HQS is non-luminescent, in contrast to what has been observed with this ligand and many other metal ions. We suggest that this is due to the presence of low-lying ligand-to-metal charge transfer (LMCT) states below the emitting ligand-based and uranyl-based levels which quench their emission. These studies have fundamental importance and are also relevant in the context of environmental studies, and the water soluble ligand 8-HQS has been chosen for application in uranium remediation of aqueous environments.
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Affiliation(s)
- M Luísa Ramos
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Licínia L G Justino
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Rui Barata
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Telma Costa
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Bernardo A Nogueira
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Rui Fausto
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Hugh D Burrows
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
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Justino LLG, Reva I, Fausto R. Thermally and vibrationally induced conformational isomerizations, infrared spectra, and photochemistry of gallic acid in low-temperature matrices. J Chem Phys 2017; 145:014304. [PMID: 27394105 DOI: 10.1063/1.4954894] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Near-infrared (near-IR) narrowband selective vibrational excitation and annealing of gallic acid (3,4,5-trihydroxybenzoic acid) isolated in cryogenic matrices were used to induce interconversions between its most stable conformers. The isomerizations were probed by infrared spectroscopy. An extensive set of quantum chemical calculations, carried out at the DFT(B3LYP)/6-311++G(d,p) level of approximation, was used to undertake a detailed analysis of the ground state potential energy surface of the molecule. This investigation of the molecule conformational space allowed extracting mechanistic insights into the observed annealing- or near-IR-induced isomerization processes. The infrared spectra of the two most stable conformers of gallic acid in N2, Xe, and Ar matrices were fully assigned. Finally, the UV-induced photochemistry of the matrix isolated compound was investigated.
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Affiliation(s)
- Licínia L G Justino
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Igor Reva
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - Rui Fausto
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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Ramos ML, Justino LLG, Abreu PE, Fonseca SM, Burrows HD. Oxocomplexes of Mo(VI) and W(VI) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and the effect of the metal ion on the photophysical behaviour. Dalton Trans 2015; 44:19076-89. [PMID: 26498366 DOI: 10.1039/c5dt03473f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multinuclear ((1)H, (13)C, (95)Mo and (183)W) NMR spectroscopy, combined with DFT calculations, provides detailed information on the complexation between the Mo(VI) and W(VI) oxoions and 8-hydroxyquinoline-5-sulfonate (8-HQS) in aqueous solution. Over the concentration region studied, Mo(VI) and W(VI) oxoions form three homologous complexes with 8-HQS in water in the pH range 2-8. Two of these, detected at pH < 6, are mononuclear 1 : 2 (metal : ligand) isomers, with the metal centre (MO2(2+)) coordinated to two 8-HQS ligands. An additional complex, dominant at slightly higher pH values (5-8) for solutions with a 1 : 1 metal : ligand molar ratio, has a binuclear M2O5(2+) centre coordinated to two 8-HQS ligands. The two metal atoms are bridged by three oxygen atoms, two coming from 8-HQS, together with the M-O-M bridge of the bimetallic centre. We show that the long-range exchange corrected BOP functional with local response dispersion (LCBOPLRD), together with explicit solvent molecules, leads to geometries that readily converge to equilibrium structures having realistic bridging O8-HQS-M bonds. Previous attempts to calculate the structures of such binuclear complexes using DFT with the B3LYP functional have failed due to difficulties in treating the weak interaction in these bridged structures. We believe that the LCBOPLRD method may be of more general application in theoretical studies in related binuclear metal complexes. UV/visible absorption and luminescence spectra of all the complexes have also been recorded. The complex between Mo(vi) and 8-HQS is only weakly luminescent, in contrast to what has been observed with this ligand and many other metal ions. We suggest that this is due to the presence of low-lying ligand-to-metal charge transfer (LMCT) states close to the emitting ligand-based level which quench the emission. However, with W(VI), DFT calculations show that the LMCT states are now much higher in energy than the ligand based levels, leading to a marked increase in fluorescence.
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Affiliation(s)
- M Luísa Ramos
- Centro de Química and Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
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Ramos ML, Justino LLG, Fonseca SM, Burrows HD. NMR, DFT and luminescence studies of the complexation of V(v) oxoions in solution with 8-hydroxyquinoline-5-sulfonate. NEW J CHEM 2015. [DOI: 10.1039/c4nj01873g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The complexation of vanadium(v) with 8-HQS is accompanied by marked changes in the multinuclear NMR and UV/visible absorption spectra of 8-HQS, but does not lead to a significant increase in fluorescence.
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Affiliation(s)
- M. Luísa Ramos
- Centro de Química de Coimbra and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - Licínia L. G. Justino
- Centro de Química de Coimbra and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - Sofia M. Fonseca
- Centro de Química de Coimbra and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - Hugh D. Burrows
- Centro de Química de Coimbra and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
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Freitas AR, Silva M, Ramos ML, Justino LLG, Fonseca SM, Barsan MM, Brett CMA, Silva MR, Burrows HD. Synthesis, structure, and spectral and electrochemical properties of chromium(iii) tris-(8-hydroxyquinolinate). Dalton Trans 2015; 44:11491-503. [DOI: 10.1039/c5dt00727e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Having the HOMO of chromium(iii) tris-(8-hydroxyquinolinate) mainly on metal 3d orbitals and the LUMO on the ligand leads to increased electrochemical stability.
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Affiliation(s)
- Ana R. Freitas
- Centro de Química and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - Mónica Silva
- Centro de Química and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - M. Luísa Ramos
- Centro de Química and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - Licínia L. G. Justino
- Centro de Química and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | - Sofia M. Fonseca
- Centro de Química and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
| | | | | | - M. Ramos Silva
- CEMDRX
- Department of Physics
- University of Coimbra
- 3004-516 Coimbra
- Portugal
| | - Hugh D. Burrows
- Centro de Química and Department of Chemistry
- University of Coimbra
- 3004-535 Coimbra
- Portugal
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Ramos ML, Justino LLG, Salvador AIN, de Sousa ARE, Abreu PE, Fonseca SM, Burrows HD. NMR, DFT and luminescence studies of the complexation of Al(III) with 8-hydroxyquinoline-5-sulfonate. Dalton Trans 2013; 41:12478-89. [PMID: 22955198 DOI: 10.1039/c2dt31381b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Multinuclear ((1)H, (13)C and (27)Al) magnetic resonance spectroscopy (1D and 2D), DFT calculations and fluorescence have been used to study the complexation of 8-hydroxyquinoline-5-sulfonate (8-HQS) with Al(III). The study combines the high sensitivity of luminescence techniques, the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to provide a detailed understanding of the complexation between the Al(3+) ion and 8-HQS. A full speciation study has been performed and over the concentration region studied, the Al(3+) ion forms complexes with 8-HQS in an aqueous solution in the pH range 2-6. At higher pH, the extensive hydrolysis of the metal limits complexation. Using Job's method, three complexes were detected, with 1 : 1, 1 : 2 and 1 : 3 (metal : ligand) stoichiometries. These results are in agreement with those previously reported using potentiometric and electrochemical techniques. The geometries of the complexes are proposed based on the combination of NMR results with optimized DFT calculations. All the complexes in aqueous solutions at 25 °C are mononuclear species, and have an approximately octahedral geometry with the metal coordinated to one molecule of 8-HQS and four molecules of water (1 : 1 complex), two molecules of 8-HQS and two molecules of water mutually cis (1 : 2 complex), and to three molecules of 8-HQS in non-symmetrical arrangement (mer-isomer), for the 1 : 3 (metal : ligand) complex. On binding to Al(III), 8-HQS shows a more marked fluorescence than the weakly fluorescent free ligand. In addition, as previously noted, there are marked changes in the absorption spectra, which support the use of 8-HQS as a sensitive optical sensor to detect Al(3+) metal ions in surface waters and biological fluids. These complexes also show potential for applications in organic light emitting diodes (OLEDs).
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Affiliation(s)
- M Luísa Ramos
- Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
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Ramos ML, de Sousa ARE, Justino LLG, Fonseca SM, Geraldes CFGC, Burrows HD. Structural and photophysical studies on gallium(iii) 8-hydroxyquinoline-5-sulfonates. Does excited state decay involve ligand photolabilisation? Dalton Trans 2013; 42:3682-94. [PMID: 23299787 DOI: 10.1039/c2dt32587j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- M Luísa Ramos
- Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
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Marques AT, Burrows HD, Seixas de Melo JS, Valente AJM, Justino LLG, Scherf U, Fron E, Rocha S, Hofkens J, Snedden EW, Monkman AP. Spectroscopic properties, excitation, and electron transfer in an anionic water-soluble poly(fluorene-alt-phenylene)-perylenediimide copolymer. J Phys Chem B 2012; 116:7548-59. [PMID: 22554070 DOI: 10.1021/jp3000703] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
An anionic fluorene-phenylene poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}-based copolymer containing on-chain perylenediimine (PDI) chromophoric units, PBS-PFP-PDI, was synthesized and its photophysical properties studied as aggregates and isolated chains in water and dioxane/water (1:1) solution. UV-vis and emission spectroscopy measurements, time-correlated single photon counting, and wide field imaging have been employed to investigate the excited-state behavior of the PBS-PFP-PDI copolymer, including the effect of environment on the energy and electron transfer to the on-chain PDI chromophore. Although the Förster overlap integral is favorable, no evidence is found for intramolecular singlet excitation energy transfer in isolated copolymer chains in solution. Fluorescence is suggested to involve an interchain process, thus revealing that isolated copolymer chains in solution do not undergo efficient intramolecular energy transfer. However, quenching of the PBS-PFP excited state by PDI is observed in aqueous media and ultrafast pump-probe studies in water or dioxane-water solutions show that electron transfer occurs from the phenylene-fluorene units to the PDI. The extent of electron transfer increases with aggregation, suggesting it is largely an interchain process. The interaction of the negatively charged PBS-PFP-PDI copolymer with the positively charged surfactant hexadecyltrimethylammonium bromide (CTAB) in solution has also been studied. The copolymer PBS-PFP-PDI aggregates with the surfactant already at concentrations below the critical micelle concentration (cmc) and the nonpolar environment allows intermolecular energy transfer, observed by the weak emission band located at 630 nm that is associated with the emission of the PDI chromophore. However, the fact that the PDI photoluminescence (PL) lifetime (~1.4 ns) obtained in the presence of CTAB is considerably shorter than that of the nonaggregated chromophore (~5.4 ns) suggests that even in this case there is considerable PL quenching, possibly through some charge transfer route. The increase of the PBS-PFP-PDI photoluminescence intensity at surfactant concentrations above the cmc indicates deaggregation of polyelectrolyte within the initially formed polyelectrolyte-surfactant aggregates.
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Affiliation(s)
- Ana T Marques
- Department of Chemistry, University of Coimbra, P3004-535 Coimbra, Portugal.
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Luísa Ramos M, Justino LLG, Branco A, Duarte CMG, Abreu PE, Fonseca SM, Burrows HD. NMR, DFT and luminescence studies of the complexation of Zn(II) with 8-hydroxyquinoline-5-sulfonate. Dalton Trans 2011; 40:11732-41. [PMID: 21964543 DOI: 10.1039/c1dt10978b] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Multinuclear ((1)H, (13)C) magnetic resonance spectroscopy, DFT calculations and luminescence techniques have been used to study 8-hydroxyquinoline-5-sulfonate (8-HQS) and its complexes with Zn(ii), in aqueous solution. The study combines the high sensitivity of luminescence techniques, the selectivity of multinuclear NMR spectroscopy with the structural details accessible through DFT calculations, and aims to obtain a detailed understanding of the complexation between the Zn(2+) ion and 8-HQS. In addition to a complete assignment of the (1)H and (13)C NMR signals of 8-HQS, a full speciation study has been performed. Over the concentration region studied, Zn(2+) metal ion forms only one significant complex species with 8-HQS in aqueous solution in the pH range 6-8. Job's method shows that this species has a 1:2 (metal:ligand) stoichiometry. The geometry around the metal centre, according to structural optimization using DFT calculations, is suggested to be square bipyramidal, with two coordinated water molecules mutually trans, and the remaining positions occupied by the donor groups of the two coordinated 8-HQS ligands. On binding to Zn(ii), 8-HQS shows a marked fluorescence compared with the weakly-luminescent free ligand. In addition, as previously noted, there are marked changes in the absorption spectra, which support the use of 8-HQS as a sensitive fluorescent sensor to detect Zn(2+) metal ion in surface waters, biological fluids, etc. Based on results of the structural studies, suggestions are made of ways for enhancing fluorescence sensitivity.
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Affiliation(s)
- M Luísa Ramos
- Departmento de Química, Universidade de Coimbra, Portugal.
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Ramos ML, Justino LLG, Burrows HD. Structural considerations and reactivity of peroxocomplexes of V(v), Mo(vi) and W(vi). Dalton Trans 2011; 40:4374-83. [DOI: 10.1039/c0dt01095b] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Justino LLG, Ramos ML, Knaapila M, Marques AT, Kudla CJ, Scherf U, Almásy L, Schweins R, Burrows HD, Monkman AP. Gel Formation and Interpolymer Alkyl Chain Interactions with Poly(9,9-dioctylfluorene-2,7-diyl) (PFO) in Toluene Solution: Results from NMR, SANS, DFT, and Semiempirical Calculations and Their Implications for PFO β-Phase Formation. Macromolecules 2010. [DOI: 10.1021/ma102235r] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Licínia L. G. Justino
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-517 Coimbra, Portugal
| | - M. Luísa Ramos
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal
- Centro de Neurociências e Biologia Celular, Universidade de Coimbra, 3004-517 Coimbra, Portugal
| | - Matti Knaapila
- Physics Department, Institute for Energy Technology, NO-2027 Kjeller, Norway
| | - Ana T. Marques
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal
- Makromolekulare Chemie, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - Christof J. Kudla
- Makromolekulare Chemie, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - Ullrich Scherf
- Makromolekulare Chemie, Bergische Universität Wuppertal, D-42097 Wuppertal, Germany
| | - László Almásy
- Laboratory for Neutron Scattering, PSI, CH-5232 Villigen, Switzerland
- Adolphe Merkle Institut, University of Fribourg, CH-1700 Fribourg, Switzerland
- Research Institute for Solid State Physics and Optics, Budapest-1525, Hungary
| | - Ralf Schweins
- Institut Laue-Langevin, DS/LSS Group, 6 Rue Jules Horowitz, F-38042 Grenoble CEDEX 9, France
| | - Hugh D. Burrows
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - Andrew P. Monkman
- OEM Research Group, Department of Physics, Durham University, Durham DH1 3LE, U.K
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Ramos ML, Justino LLG, Gil VMS, Burrows HD. NMR and DFT studies of the complexation of W(VI) and Mo(VI) with 3-phospho-D-glyceric and 2-phospho-D-glyceric acids. Dalton Trans 2009:9616-24. [PMID: 19859617 DOI: 10.1039/b905933d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multinuclear ((1)H, (13)C, (17)O, (31)P, (95)Mo, (183)W) magnetic resonance spectroscopy (1D and 2D) has been used to study the complexation of molybdate(VI) and tungstate(VI) with 3-phospho-D-glyceric and 2-phospho-D-glyceric acids. 3-Phospho-D-glyceric acid forms four and five complexes, respectively, with molybdate and tungstate. These have MO(2)(2+) centres, and involve the carboxylate and the adjacent OH groups. Two isomeric 1:2 (metal-ligand) complexes are detected, in addition to one mononuclear species having MO(3) centres and involving the ligand in a tridentate chelation and a dominant 12:4 species with both tungstate(VI) and molybdate(VI). The dominant 12:4 species can be seen as two 1:2 complexes bound together in a ring through two diphosphometalate moieties, derived from heptamolybdate or heptatungstate, respectively, by inclusion of two phosphate groups from the ligands. Tungstate is also able to form an additional 2:1 tridentate species. 2-Phospho-D-glyceric acid does not interact with tungstate but is able to form one phosphomolybdate species with molybdate, which can be regarded as a heptamolybdate derivative. Density functional theory (DFT) calculations were performed for 1:2 complexes, including calculations on the relative energies of the 1:2 complexes detected in related systems, to validate previously proposed structures. The results are compared with those obtained from multinuclear NMR spectroscopy.
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Affiliation(s)
- M Luísa Ramos
- Departmento de Química, Universidade de Coimbra, 3004-535, Coimbra, Portugal.
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Justino LLG, Ramos ML, Abreu PE, Carvalho RA, Sobral AJFN, Scherf U, Burrows HD. Conformational studies of poly(9,9-dialkylfluorene)s in solution using NMR spectroscopy and density functional theory calculations. J Phys Chem B 2009; 113:11808-21. [PMID: 19663434 DOI: 10.1021/jp902666e] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Relationships have been obtained between intermonomer torsional angle and NMR chemical shifts ((1)H and (13)C) for isolated chains of two of the most important poly(9,9-dialkylfluorenes), poly[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl] (PF2/6) and the copolymer poly(9,9-dioctylfluorene-co-[2,1,3]benzothiadiazole-4,7-diyl) (F8BT), using DFT calculations. The correlations provide a model for NMR spectral data interpretation and the basis for analysis of conformational changes in poly(9,9-dialkylfluorene-2,7-diyl)s. The correlations obtained for PF2/6 indicate that the (13)C chemical shifts of the aromatic carbons close to the intermonomer connection (C1, C2, and C3) have minimum values at planar conformations (0 degrees and 180 degrees ) and maximum values at 90 degrees conformations. In contrast, the (1)H chemical shifts of the corresponding aromatic ortho protons (Ha and Hb) are greatest for planar conformations, and the minimum values are seen for 90 degrees conformations. For the F8BT copolymer, similar relationships are observed for the (1)H (Ha, Hb, and Hc) aromatic shifts. Considering the aromatic carbons of F8BT, the behavior of C2, C4, C5, and C6 is similar to that found for the PF2/6 carbons. However, C1 and C3 of the fluorene moiety behave differently with varying torsion angle. These are in close proximity to the fluorene-benzothiadiazole linkage and are markedly affected by interactions with the thiadiazole unit such that delta(C1) is a maximum for 180 degrees and a minimum for 0 degrees , whereas delta(C3) is a maximum for 0 degrees and minimum for 180 degrees. We have studied the (1)H and (13)C spectra of the two polymers at temperatures between -50 degrees C and +65 degrees C. The observed changes to higher or lower frequency in the aromatic resonances were analyzed using these theoretical relationships. Fluorescence studies on PF2/6 in chloroform solution suggest there are no significant interchain interactions under these conditions. This is supported by variable-temperature NMR results. Polymer-solvent and polymer intramolecular interactions were found to be present and influence all of the alkylic and one of the aromatic (1)H resonances (Hb). The detailed attribution of the (1)H and (13)C NMR spectra of the two polymers was made prior to the establishment of the relationships between torsion angle and NMR chemical shifts. This was carried out through DFT calculation of the (1)H and (13)C shielding constants of the monomers, coupled with distortionless enhancement by polarization transfer and heteronuclear correlation NMR spectra. Several DFT levels of calculation were tested for both optimization of structures and shielding constants calculation. The B3LYP/6-31G(d,p) method was found to perform well in both cases.
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Affiliation(s)
- Licínia L G Justino
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
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Burrows HD, Tapia MJ, Fonseca SM, Valente AJM, Lobo VMM, Justino LLG, Qiu S, Pradhan S, Scherf U, Chattopadhyay N, Knaapila M, Garamus VM. Aqueous solution behavior of anionic fluorene-co-thiophene-based conjugated polyelectrolytes. ACS Appl Mater Interfaces 2009; 1:864-874. [PMID: 20356013 DOI: 10.1021/am800267n] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Two anionic fluorene-thiophene alternating copolymers, poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-2,5-thienylene] (PBS-PFT) and poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-2,2'-bithiophene-5,5'-diyl] (PBS-PF2T), have been synthesized and their solution behaviors in water studied by UV-vis absorption spectroscopy, fluorescence, and electrical conductivity and compared with that of the previously studied conjugated polyelectrolyte (CPE) poly[9,9-bis(4-sulfonylbutoxyphenyl)fluorene-2,7-diyl-1,4-phenylene] (PBS-PFP). These conjugated polymers do not form solutions at the molecular level in water but instead form clusters. Information on the structure of these clusters for PBS-PF2T comes from small-angle X-ray and neutron scattering. The relative ease of dispersing the copolymers in water increases with an increase in the number of thiophene rings in these alternating copolymers. Semiempirical calculations on the structure suggest that this results from bending of the chains and increased conformational flexibility, decreasing interchain interactions. These CPEs can be dissolved in water at the molecular level using the nonionic surfactants n-dodecylpentaoxyethylene glycol ether (C12E5) or Triton X-100 to obtain systems with increased photoluminescence quantum yield and increased electrical conductivity that can be solution-processed for potential applications as components of sensory or optoelectronic devices.
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Affiliation(s)
- Hugh D Burrows
- Departamento de Quimica and Centro de Neurociencias e Biologia Celular, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
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Justino LLG, Ramos ML, Kaupp M, Burrows HD, Fiolhais C, Gil VMS. Density functional theory study of the oxoperoxo vanadium(V) complexes of glycolic acid. Structural correlations with NMR chemical shifts. Dalton Trans 2009:9735-45. [DOI: 10.1039/b910033d] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Justino LLG, Ramos ML, Nogueira F, Sobral AJFN, Geraldes CFGC, Kaupp M, Burrows HD, Fiolhais C, Gil VMS. Oxoperoxo Vanadium(V) Complexes of l-Lactic Acid: Density Functional Theory Study of Structure and NMR Chemical Shifts. Inorg Chem 2008; 47:7317-26. [DOI: 10.1021/ic800405x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Licínia L. G. Justino
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - M. Luísa Ramos
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Fernando Nogueira
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Abilio J. F. N. Sobral
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Carlos F. G. C. Geraldes
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Martin Kaupp
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Hugh D. Burrows
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Carlos Fiolhais
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
| | - Victor M. S. Gil
- Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-535 Coimbra, Portugal, Departamento de Física e Centro de Física Computacional, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3004-516 Coimbra, Portugal, Departamento de Bioquímica, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, 3001-401 Coimbra, Portugal, Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Portugal, and Institut für Anorganische Chemie, Universität
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