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Conventional and microwave prompted synthesis of aryl(alkyl)azole oximes, 1H-NMR spectroscopic determination of E/Z isomer ratio and HOMO-LUMO analysis. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2021.132077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Theoretical study of new conjugated compounds with a low bandgap for bulk heterojunction solar cells: DFT and TD-DFT study. RESULTS IN CHEMISTRY 2020. [DOI: 10.1016/j.rechem.2020.100040] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Oligo p-Phenylenevinylene Derivatives as Electron Transfer Matrices for UV-MALDI. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2548-2560. [PMID: 28879637 DOI: 10.1007/s13361-017-1783-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 08/10/2017] [Accepted: 08/10/2017] [Indexed: 06/07/2023]
Abstract
Phenylenevinylene oligomers (PVs) have outstanding photophysical characteristics for applications in the growing field of organic electronics. Yet, PVs are also versatile molecules, the optical and physicochemical properties of which can be tuned by manipulation of their structure. We report the synthesis, photophysical, and MS characterization of eight PV derivatives with potential value as electron transfer (ET) matrices for UV-MALDI. UV-vis analysis show the presence of strong characteristic absorption bands in the UV region and molar absorptivities at 355 nm similar or higher than those of traditional proton (CHCA) and ET (DCTB) MALDI matrices. Most of the PVs exhibit non-radiative quantum yields (φ) above 0.5, indicating favorable thermal decay. Ionization potential values (IP) for PVs, calculated by the Electron Propagator Theory (EPT), range from 6.88 to 7.96 eV, making these oligomers good candidates as matrices for ET ionization. LDI analysis of PVs shows only the presence of radical cations (M+.) in positive ion mode and absence of clusters, adducts, or protonated species; in addition, M+. threshold energies for PVs are lower than for DCTB. We also tested the performance of four selected PVs as ET MALDI matrices for analytes ranging from porphyrins and phthalocyanines to polyaromatic compounds. Two of the four PVs show S/N enhancement of 1961% to 304% in comparison to LDI, and laser energy thresholds from 0.17 μJ to 0.47 μJ compared to 0.58 μJ for DCTB. The use of PV matrices also results in lower LODs (low fmol range) whereas LDI LODs range from pmol to nmol. Graphical Abstract ᅟ.
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Mechanosynthesis of a phenylenedivinylidenebisquinoline. Optical, morphological and electroluminescence properties. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.01.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Mechanism and Dynamics of Electron Injection and Charge Recombination in DNA. Dependence on Neighboring Pyrimidines. J Phys Chem B 2015; 119:7673-80. [DOI: 10.1021/jp512113w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Carbon-bridged oligo(phenylenevinylene)s: stable π-systems with high responsiveness to doping and excitation. J Am Chem Soc 2012; 134:19254-9. [PMID: 23106224 DOI: 10.1021/ja309318s] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The high responsiveness of π-conjugated materials to external stimuli, such as electrons and photons, accounts for both their utility in optoelectronic applications and their chemical instability. Extensive studies on heteroatom-stabilized π-conjugated systems notwithstanding, it is still difficult to combine high performance and stability. We report here that carbon-bridged oligo(p-phenylenevinylene)s (COPV-n) are not only more responsive to doping and photoexcitation but also more stable than the conventional p-phenylenevinylenes and poly(3-hexylthiophene), surviving photolysis very well in air, suggesting that they could serve as building blocks for optoelectronic applications. Activation of the ground state by installation of bond angle strain toward the doped or photoexcited state and the flat, rigid, and hindered structure endows COPVs with stimuli-responsiveness and stability without recourse to heteroatoms. For example, COPV-6 can be doped with an extremely small reorganization energy and form a bipolaron delocalized over the entire π-conjugated system. Applications to bulk and molecular optoelectronic devices are foreseen.
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Theoretical design of polythienylenevinylene derivatives for improvements of light-emitting and photovoltaic performances. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm14956c] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Electron localization and the transition from adiabatic to nonadiabatic charge transport in organic conductors. Chem Soc Rev 2010; 39:2484-99. [DOI: 10.1039/b909058b] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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] [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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Radical Cations of All-Trans Oligodiacetylenes: Optical Absorption and Reactivity toward Nucleophiles. J Phys Chem B 2009; 113:11095-100. [DOI: 10.1021/jp903081p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Investigation of Charge Carriers in Doped Thiophene Oligomers through Theoretical Modeling of their UV/Vis Spectra. J Phys Chem A 2008; 112:5458-66. [DOI: 10.1021/jp800606m] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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New materials based on carbazole for optoelectronic device applications: Theoretical investigation. CHINESE CHEM LETT 2008. [DOI: 10.1016/j.cclet.2007.12.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Theoretical study of structural and electronic properties of oligo(thiophene-phenylene)s in comparison with oligothiophenes and oligophenylenes. CHINESE CHEM LETT 2008. [DOI: 10.1016/j.cclet.2007.10.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Structure and electric properties of poly(vinylidene fluoride–tetrafluoroethylene) copolymer studied with density functional theory. POLYMER 2007. [DOI: 10.1016/j.polymer.2007.09.029] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
The ion radicals of two series of platinum acetylide oligomers have been subjected to study by electrochemical and pulse radiolysis/transient absorption methods. One series of oligomers, Ptn, has the general structure Ph-C[triple bond]C-[Pt(PBu3)2-C[triple bond]C-(1,4-Ph)-C[triple bond]C-]n-Pt(PBu3)2-C[triple bond]C-Ph (where x=0-4, Ph=phenyl and 1,4-Ph=1,4-phenylene). The second series of oligomers, Pt4Tn, contain a thiophene oligomer core, -C[triple bond]C-(2,5-Th)n-C[triple bond]C- (where n=1-3 and 2,5-Th=2,5-thienylene), capped on both ends with -Pt(PBu3)2-C[triple bond]C-(1,4-Ph)-C[triple bond]C-Pt(PBu3)2-C[triple bond]C-Ph segments. Electrochemical studies reveal that all of the oligomers feature reversible or quasi-reversible one-electron oxidation at potentials less than 1 V versus SCE. These oxidations are assigned to the formation of radical cations on the platinum acetylide chains. For the longer oligomers multiple, reversible one-electron waves are observed at potentials less than 1 V, indicating that multiple positive polarons can be produced on the oligomers. Pulse-radiolysis/transient absorption spectroscopy has been used to study the spectra and dynamics of the cation and anion radical states of the oligomers in dichloroethane and tetrahydrofuran solutions, respectively. All of the ion radicals exhibit two allowed absorption bands: one in the visible region and the second in the near-infrared region. The ion radical spectra shift with oligomer length, suggesting that the polarons are delocalized to some extent on the platinum acetylide chains. Analysis of the electrochemical and pulse radiolysis data combined with the density functional theory calculations on model ion radicals provides insight into the electronic structure of the positive and negative ion radical states of the oligomers. A key conclusion of the work is that the polaron states are concentrated on relatively short oligomer segments.
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DFT calculations of the local spin densities and oligomerization mechanism of thiophene–phenylene (TP) co-oligomers and derivatives. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2007.02.043] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Theoretical Investigation of Excited States of Oligothiophenes and of Their Monocations. J Chem Theory Comput 2007; 3:1143-57. [DOI: 10.1021/ct600344u] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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Molecular modeling of poly(p-phenylenevinylene): Synthesis and photophysical properties of oligomers. ACTA ACUST UNITED AC 2007. [DOI: 10.1002/pola.21862] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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A Joint Experimental and Computational Study on the Electronic Communication in Diethynylaryl-Bridged (η5-C5H5)Fe(η2-dppe) and (η5-C5H5)Fe(CO)2 Units. Eur J Inorg Chem 2006. [DOI: 10.1002/ejic.200600024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Solvent and Linker Influences on AQ•-/dA•+Charge-Transfer State Energetics and Dynamics in Anthraquinonyl-Linker-Deoxyadenosine Conjugates. J Phys Chem A 2006; 110:4320-8. [PMID: 16571034 DOI: 10.1021/jp054395q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The goal of this work is to produce high yields of long-lived AQ(*-)/dA(*+) charge transfer (CT) excited states (or photoproducts). This goal fits within a larger context of trying generally to produce high yields of long-lived CT excited states within DNA nucleoside conjugates that can be incorporated into DNA duplexes. Depending upon the energetics of the anthraquinonyl (AQ) (3)(pi,pi) state as well as the reduction potentials of the subunits in particular anthraquinonyl-adenine conjugates, CT quenching of the AQ (3)(pi,pi*) state may or may not occur in polar organic solvents. In MeOH, bis(3',5'-O-acetyl)-N(6)-(anthraquinone-2-carbonyl)-2'-deoxyadenosine (AQCOdA) behaves as intended and forms a (3)(AQ(*-)/dA(*+)) CT state with a lifetime of 3 ns. However, in nonpolar THF the AQ(*-)/dA(*+) CT states of AQCOdA are too high in energy to be formed, and in DMSO a (1)(AQ(*-)/dA(*+)) CT state is formed but lives only 6 ps. Although the lowest energy excited state for AQCOdA in MeOH is a (3)(AQ(*-)/dA(*+)) CT state, for N(6)-(anthraquinone-2-methylenyl)-2'-deoxyadenosine (AQMedA) in the same solvent it is a (3)(pi,pi*) state. Changing the linking carbonyl in AQCOdA to methylene in AQMedA makes the anthraquinonyl subunit harder to reduce by 166 mV. This raises the energy of the (3)(AQ(*-)/dA(*+)) CT state above that of the (3)(pi,pi*) in AQMedA. The conclusion is that anthraquinonyl-dA conjugates will not have lowest energy AQ(*-)/dA(*+) CT states in polar organic solvents unless the anthraquinonyl subunit is also substituted with an electron-withdrawing group that raises the AQ-subunit's reduction potential above that of AQ. A key finding in this work is that the lifetime of the (3)(AQ(*-)/dA(*+)) CT excited state (ca. 3 ns) is ca. 500-times longer than that of the corresponding (1)(AQ(*-)/dA(*+)) CT excited state (ca. 6 ps).'
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Electronic Structure and Optical Properties of Charged Oligofluorenes Studied by VIS/NIR Spectroscopy and Time-Dependent Density Functional Theory. J Phys Chem B 2006; 110:5984-93. [PMID: 16553407 DOI: 10.1021/jp055785f] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The electronic structure and optical properties of charged oligofluorenes were studied experimentally and theoretically. Measurements of the optical absorption spectra of charged oligofluorenes in dilute solutions have been performed by using the pulse radiolysis technique. In addition, optical absorption spectra of radical cations and anions in a solid matrix were measured after gamma-irradiation at 77 K. The optical absorption spectra were measured in the range of 440-2100 nm (0.6-2.8 eV) and compared with results from time-dependent density functional theory (TDDFT) calculations. The calculated charge induced deformations and charge distribution do not indicate the occurrence of polaronic effects. The potential energy profiles for rotation around the inter-unit bond show that oligofluorenes are nonplanar in their neutral state, while they tend to more planar structures in their charged state. The optical absorption spectra of charged oligofluorenes are dependent on the angle between neighboring units. TDDFT absorption energies shift to lower values with increasing chain length, which suggests that the charge delocalizes along the oligomer chain.
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A theoretical investigation on the electronic and optical properties of π-conjugated copolymers with an efficient electron-accepting unit bithieno[3,2-b:2′3′-e]pyridine. POLYMER 2005. [DOI: 10.1016/j.polymer.2005.07.058] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Impact of the Computational Method on the Geometric and Electronic Properties of Oligo(phenylene vinylene) Radical Cations. J Phys Chem B 2005; 109:20237-43. [PMID: 16853617 DOI: 10.1021/jp0519417] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on a quantum-chemical study of the electronic and optical properties of unsubstituted oligo(phenylene vinylene) (OPV) radical cations. Our goal is to distinguish the impact of the choice of molecular geometry from the impact of the choice of quantum-chemical method, on the calculated optical transition energies. The geometry modifications upon ionization of the OPV chains are found to depend critically on the theoretical formalism: Hartree-Fock (HF) geometry optimizations lead to self-localization of the charged defects while pure density functional theory (DFT) results in a complete delocalization of the geometric modifications over the whole conjugated backbone. The electronic structure and vertical transition energy associated with the lowest excited state of the radical cations have been calculated at the post-Hartree-Fock level within a configuration interaction (HF-CI) scheme and using the time-dependent DFT (TD-DFT) formalism for different radical cation geometries. Interestingly, the changes in the calculated optical properties obtained when using different geometric structures are less important within a given method than the differences between methods for a given structure. The optical excitation is localized with HF-CI and delocalized with TD-DFT, almost irrespective of the molecular geometry; as a result, HF-CI excitation energies tend to saturate as the chain length increases, in contrast to the results from TD-DFT.
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Highly mobile electrons and holes on polyfluorene chains formed by charge scavenging in pulse-irradiated trans-decalin solutions. Radiat Phys Chem Oxf Engl 1993 2005. [DOI: 10.1016/j.radphyschem.2005.04.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Charge Transport in Self-Organized π-Stacks of p-Phenylene Vinylene Oligomers. J Phys Chem B 2005; 109:18267-74. [PMID: 16853350 DOI: 10.1021/jp053017i] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
We have studied the mobility of charge carriers along self-organizing pi-stacks of hydrogen-bonded phenylene vinylene oligomers in solution, by time-resolved microwave conductivity measurements. The value deduced for the mobility along the stacks is 3 x 10(-3) and 9 x 10(-3) cm2/(V s) for holes and electrons, respectively. Additionally, we have calculated the mobility along the pi-stacks using a hopping model based on parameters from density functional theory. The mobility values obtained from these calculations are in good agreement with the experimental values if it is assumed that there are relatively large twist angles between neighboring molecules in the stack. It is shown that a significantly higher mobility can be attained if the twist angle between neighboring oligomers is reduced.
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Theoretical studies of the modulation of polymer electronic and optical properties through the introduction of the electron-donating 3,4-ethylenedioxythiophene or electron-accepting pyridine and 1,3,4-oxadiazole moieties. J Phys Chem A 2005; 109:7764-74. [PMID: 16834153 DOI: 10.1021/jp0515277] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One serious problem associated with polyfluorene and derivatives (PFs) as blue luminescent polymers is the significant energy barrier for hole or electron injections; thus they usually face charge injection and transport difficulties with the currently available cathode and anode materials. The incorporation of an electron-donating or -accepting unit is expected to improve the recombination of the charge carriers. In this paper, we apply quantum-chemical techniques to investigate three fluorene-based copolymers, copoly(2,5-ethylenedioxythiophene-alt-9,9'-dimethylfluorene) (PEF), copoly(2,5-pyridine-alt-9,9'-dimethylfluorene) (PPyF), and poly[(fluorene-2,7-diyl)-alt-(1,3,4-oxadiazole-2,5-diyl)] (PFO), in which Delta(H)(-)(L) [the energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), when n = infinity], the lowest excitation energies (E(g)), ionization potentials (IP), electron affinities (EA), and lambda(abs) and lambda(em) are fine-tuned by the regular insertion of electron-donating unit 3,4-ethylenedioxythiophene (EDOT) or electron-withdrawing units pyridine and 1,3,4-oxadiazole. The results show that the alternate incorporation of electron-donating moiety EDOT increases the HOMO energy and thus reduces the IPs, and consequently the hole injection was greatly improved. On the other hand, even though both kinds of charge carriers will improve the electron-accepting ability, the results show that electron-withdrawing moieties greatly facilitate the electron-transporting. Especially in PFO, the highly planar structural character resulted from the strong push-pull effect between the fluorene ring and the 1,3,4-oxadiazole ring and a weak interaction between the nitrogen and oxygen atoms in 1,3,4-oxadiazole ring and the hydrogen atom of the fluorene ring, significantly lowering the LUMO energy levels and thus improve the electron-accepting and transporting properties by the low LUMO energy levels.
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The Opto-Electronic Properties of Isolated Phenylenevinylene Molecular Wires. ACTA ACUST UNITED AC 2005; 257:135-64. [DOI: 10.1007/b136065] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
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Computational Study of the Structure, Dynamics, and Photophysical Properties of Conjugated Polymers and Oligomers under Nanoscale Confinement. J Phys Chem B 2005; 109:7671-85. [PMID: 16851891 DOI: 10.1021/jp0446534] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Computational simulations were used to investigate the dynamics and resulting structures of several para-phenylenevinylene (PPV) based polymers and oligomers (PPV, 2-methoxy-5-(2'-ethyl-hexyloxy)-p-phenylenevinylene --> MEH-PPV and 2,5,2',5'-tetrahexyloxy-7,8'-dicyano-p-phenylenevinylene --> CN-PPV). The results show how the morphology and structure are controlled to a large extent by the nature of the solute-solvent interactions in the initial solution-phase preparation. Secondary structural organization is induced by using the solution-phase structures to generate solvent-free single molecule nanoparticles. Isolation of these single molecule nanostructures from microdroplets of dilute solution results in the formation of electrostatically oriented nanostructures at a glass surface. Our structural modeling suggests that these oriented nanostructures consist of folded PPV conjugated segments with folds occurring at tetrahedral defects (sp3 C-C bonds) within the polymer chain. This picture is supported by detailed experimental fluorescence and scanning probe microscopy studies. We also present results from a fully quantum theoretical treatment of these systems which support the general conclusion of structure-mediated photophysical properties.
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Optical Properties and Delocalization of Excess Negative Charges on Oligo(Phenylenevinylene)s: A Quantum Chemical Study. J Phys Chem B 2005; 109:5644-52. [PMID: 16851609 DOI: 10.1021/jp0443310] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A quantum chemical study of the electronic structure of negatively charged phenylenevinylene (PV) oligomers and methoxy-substituted derivatives is presented. The geometries of the PV oligomers were optimized using density functional theory. The geometry deformations are found to be delocalized along the entire oligomer chain without indication of polaron formation. The optical absorption spectra of the negatively charged PVs were calculated using both time-dependent density functional theory (TDDFT) and the singly excited configuration interaction method with an intermediate neglect of differential overlap reference wave function (INDO/s-CIS). The available experimental optical absorption energies are reproduced by the calculations. Introduction of methoxy substituents reduces the transition energies, while this does not have a strong effect on the charge distribution along the chain. DFT calculations yield a more delocalized excess negative charge than that of INDO/s-CIS calculations.
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VIS/NIR Absorption Spectra of Positively Charged Oligo(phenylenevinylene)s and Comparison with Time-Dependent Density Functional Theory Calculations. J Phys Chem B 2004. [DOI: 10.1021/jp046665v] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Optical properties of singly charged conjugated oligomers: A coupled-cluster equation of motion study. J Chem Phys 2004; 121:5567-78. [PMID: 15366979 DOI: 10.1063/1.1776113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We have implemented a coupled-cluster equation of motion approach combined with the intermediate neglect of differential overlap parametrization and applied it to study the excited states and optical absorptions in positively and negatively charged conjugated oligomers. The method is found to be both reliable and efficient. The theoretical results are in very good agreement with experiments and confirm that there appear two subgap absorption peaks upon polaron formation. Interestingly, the relative intensities of the polaron-induced subgap absorptions can be related to the extent of the lattice geometry relaxations.
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Electronic Structure of Thienylene Vinylene Oligomers: Singlet Excited States, Triplet Excited States, Cations, and Dications. J Phys Chem B 2004. [DOI: 10.1021/jp048445n] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Effect of an external electric field on the charge transport parameters in organic molecular semiconductors. J Chem Phys 2003. [DOI: 10.1063/1.1625918] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Conformational dynamics of phenylene rings in poly(p-phenylene vinylene) as revealed by 13C magic-angle-spinning exchange nuclear magnetic resonance experiments. J Chem Phys 2003. [DOI: 10.1063/1.1585024] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Tuning of the excited state properties of phenylenevinylene oligomers: A time-dependent density functional theory study. J Chem Phys 2003. [DOI: 10.1063/1.1568079] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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