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Qin X, Li M, Xiang M, Luo Y, Jiao Y, Yuan R, Wang N, Lu Z, Pu X. Probing the Effects of the Number and Positions of -OCH 3 and -CN Substituents on Color Tuning of Ir(III) Complex Derivatives through a Joint Computational and Experimental Study. Chemphyschem 2019; 20:470-481. [PMID: 30479051 DOI: 10.1002/cphc.201800928] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 11/13/2018] [Indexed: 11/11/2022]
Abstract
We performed a joint theoretical and experimental study on sixteen Ir(III) complexes bearing a similar molecular platform of bis(2-phenylbenzothiozolato-N,C2' ) iridium(III) (acetylacetonate) by grafting -OCH3 group and/or -CN group on different positions of the C-related arene moiety of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>C</mml:mi> <mml:mspace/> <mml:mover><mml:mspace/> <mml:mo>^</mml:mo></mml:mover> <mml:mspace/> <mml:mi>N</mml:mi></mml:mrow> </mml:math> ligand (C-ring). Our results reveal that the introduction of -CN renders an overall drop in the FMO energy levels while a reverse increase is observed for -OCH3 . The ortho- and para-sites of the C-ring are more effective substitution positions to modulate the HOMO energy level due to the fact that the electronic density of HOMO mainly locates at them while the meta-site would induce a stronger impact on LUMO since the electronic density of LUMO mainly distributes over the position. Utilizing the synergistic effects of the substituents and the substituted positions, a wide color-tuning range from 479 nm to 637 nm was achieved, which covers nearly the whole window of visible spectrum. In particular, the tri-substituted Ir35mo4cn complex (λem max =637 nm) may be a potential candidate for high efficiency red OLEDs materials due to its greatly enhanced absorption processes, relatively higher 3 MLCT (%), lower ΔES1-T1 , enlarged separation between 3 MLCT/π-π* and 3 MC d-d states, and good hole and particle-transporting performances. Finally, six representative complexes were synthesized and their spectra were determined, which confirm the reliability of our computational strategy.
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Affiliation(s)
- Xiao Qin
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Ming Li
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Minghui Xiang
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Yi Luo
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Yan Jiao
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Rongao Yuan
- Sichuan Chengdu NO.7 High School, Chengdu, 610041, People's Republic of China
| | - Ning Wang
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Zhiyun Lu
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
| | - Xumei Pu
- Department of Chemistry, Sichuan University, Chengdu, 610064, People's Republic of China
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2
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Shang X, Han D, Liu M, Zhang G. A theoretical study on the electronic and photophysical properties of two series of iridium(iii) complexes with different substituted N^N ligand. RSC Adv 2017. [DOI: 10.1039/c6ra27631h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The density functional theory has been applied to explore the geometrical, electronic and photophysical properties of the recently reported pyrazolyl-pyridine- or triazolyl-pyridine-containing iridium(iii) complexes 1 and 2.
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Affiliation(s)
- Xiaohong Shang
- College of Chemistry and Life Science
- Changchun University of Technology
- Changchun 130012
- P. R. China
| | - Deming Han
- School of Life Science and Technology
- Changchun University of Science and Technology
- Changchun 130022
- P. R. China
| | - Mei Liu
- College of Chemistry and Life Science
- Changchun University of Technology
- Changchun 130012
- P. R. China
| | - Gang Zhang
- Institute of Theoretical Chemistry
- Jilin University
- Changchun 130023
- P. R. China
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3
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Shang X, Han D, Zhou D, Zhang G. Shedding light on the photophysical properties of iridium(iii) complexes with a dicyclometalated phosphate ligand via N-substitution from a theoretical viewpoint. NEW J CHEM 2017. [DOI: 10.1039/c6nj03617a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The geometrical structures and phosphorescence efficiency of two series of iridium(iii) complexes with wide-range color tuning have been focused on in this work.
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Affiliation(s)
- Xiaohong Shang
- College of Chemistry and Life Science
- Changchun University of Technology
- Changchun 130012
- P. R. China
| | - Deming Han
- School of Life Science and Technology
- Changchun University of Science and Technology
- Changchun 130022
- P. R. China
| | - Defeng Zhou
- College of Chemistry and Life Science
- Changchun University of Technology
- Changchun 130012
- P. R. China
| | - Gang Zhang
- Institute of Theoretical Chemistry
- Jilin University
- Changchun 130023
- P. R. China
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4
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Abstract
Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.
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Affiliation(s)
- Oksana Ostroverkhova
- Department of Physics, Oregon State University , Corvallis, Oregon 97331, United States
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5
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Thorat KG, Kamble P, Ray AK, Sekar N. Novel pyrromethene dyes with N-ethyl carbazole at the meso position: a comprehensive photophysical, lasing, photostability and TD-DFT study. Phys Chem Chem Phys 2016; 17:17221-36. [PMID: 26074136 DOI: 10.1039/c5cp01741f] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Two novel BODIPY (pyrromethene, PM) dyes containing N-ethyl carbazole at the meso position are synthesized and their photophysical properties in different solvents and the photochemical stabilities and laser performances in n-heptane are investigated. The n-heptane solution of the dyes was used as a gain medium in a constructed narrow band dye laser, pumped by a Q-switched (10 Hz) frequency-doubled (532 nm) Nd:YAG laser and the results gave enhanced photo stabilities and similar peak efficiencies of the synthesized dyes as compared to parent dye PM567. When substituted at the meso position with N-alkyl carbazole, photostability is found to be increased in comparison to PM567, and also when substituted at 2- and 6-positions with a benzyl group instead of an ethyl group along with N-ethyl carbazole at the meso position, the photo stability is further increased in n-heptane. A comprehensive study on structural, photophysical and electronic properties of dyes by means of DFT and TD-DFT in the solvents of various polarities has revealed remarkable characteristics of the BODIPY chromophore.
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Affiliation(s)
- Kishor G Thorat
- Dyestuff Technology Department, Institute of Chemical Technology, Mumbai-400019, India.
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6
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Li J, Zhang Q, He H, Wang L, Zhang J. Tuning the electronic and phosphorescence properties of blue-emitting iridium(iii) complexes through different cyclometalated ligand substituents: a theoretical investigation. Dalton Trans 2015; 44:8577-89. [DOI: 10.1039/c5dt00048c] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A DFT/TDDFT investigation was performed to estimate the OLED performance of six reported and seven newly designed iridium(iii) complexes.
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Affiliation(s)
- Jieqiong Li
- Institute of Environmental and Analytical Sciences
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng
- P.R. China
| | - Qing Zhang
- Institute of Environmental and Analytical Sciences
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng
- P.R. China
| | - Hongqing He
- Wuhan Center for Magnetic Resonance
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics
- Wuhan Institute of Physics and Mathematics
- Chinese Academy of Sciences
- Wuhan 430071
| | - Li Wang
- Institute of Environmental and Analytical Sciences
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng
- P.R. China
| | - Jinglai Zhang
- Institute of Environmental and Analytical Sciences
- College of Chemistry and Chemical Engineering
- Henan University
- Kaifeng
- P.R. China
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7
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Si Y, Zhang S, Qu N, Luan G, Wu Z. Enhancing the electronic properties and quantum efficiency of sulfonyl/phosphoryl-substituted blue iridium complexes via different ancillary ligands. NEW J CHEM 2015. [DOI: 10.1039/c5nj00316d] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influence of the ancillary ligands for iridium complexes on the electronic structures, absorption and emission spectra, and quantum efficiency was investigated. The results reveal that they not only tune the energy gap but also enhance the quantum efficiency.
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Affiliation(s)
- Yanling Si
- College of Resource and Environmental Science
- Jilin Agricultural University
- Changchun
- P. R. China
| | - Shuai Zhang
- College of Resource and Environmental Science
- Jilin Agricultural University
- Changchun
- P. R. China
| | - Nan Qu
- College of Resource and Environmental Science
- Jilin Agricultural University
- Changchun
- P. R. China
| | - Guoyou Luan
- College of Resource and Environmental Science
- Jilin Agricultural University
- Changchun
- P. R. China
| | - Zhijian Wu
- State Key Laboratory of Rare Earth Resource Utilization
- Changchun Institute of Applied Chemistry
- Chinese Academy of Sciences
- Changchun 130022
- P. R. China
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8
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Si Y, Sun X, Liu Y, Qu X, Wang Y, Wu Z. A DFT/TDDFT study on the effect of CN substitution on color tuning and phosphorescence efficiency of a series of Ir(iii) complexes with phosphine-silanolate ligands. Dalton Trans 2014; 43:714-21. [DOI: 10.1039/c3dt52273c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Qu X, Liu Y, Si Y, Wu X, Wu Z. A theoretical study on supramolecularly-caged positively charged iridium(iii) 2-pyridyl azolate derivatives as blue emitters for light-emitting electrochemical cells. Dalton Trans 2014; 43:1246-60. [DOI: 10.1039/c3dt51888d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Liu Y, Sun X, Si Y, Qu X, Wang Y, Wu Z. Tuning the electronic properties and quantum efficiency of blue Ir(iii) carbene complexes via different azole-pyridine-based N^N′ ligands. RSC Adv 2014. [DOI: 10.1039/c3ra46804f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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11
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Qu X, Liu Y, Godefroid G, Si Y, Shang X, Wu X, Wu Z. Theoretical Study on Cationic Iridium(III) Complexes with a Diphosphane Ligand - Geometry, Electronic Properties, and Application for Light-Emitting Electrochemical Cells. Eur J Inorg Chem 2013. [DOI: 10.1002/ejic.201300159] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Terentjevs A, Fabiano E, Della Sala F. Theoretical investigation of molecular excited states in polar organic monolayers via an efficient embedding approach. Theor Chem Acc 2012. [DOI: 10.1007/s00214-012-1154-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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13
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Viola I, Piliego C, Favaretto L, Barbarella G, Cingolani R, Gigli G. Bicolor electroluminescent pixels from single active molecular material. ACS APPLIED MATERIALS & INTERFACES 2010; 2:484-490. [PMID: 20356195 DOI: 10.1021/am9007227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We report on the fabrication of the first bicolor micropixelated OLED from a single molecular material using a single-step bottom up procedure. The implementation of a deposition technique, based on a spatial-switch and conformational-sensitive STD surface-tension-driven lithography, has allowed us to exploit the spontaneous supramolecular properties and the conformational flexibility of a conjugated thiophene-based material, 6-bis-(50-hexyl-[2, 20]bithiophen-5-yl)-3, 5-dimethyl-dithieno[3, 2-b; 20, 30-d]thiophene (DTT7Me). The existence of two regularly alternating emitting regions on a micrometer scale allows obtaining electroluminescent emission at two different wavelengths from a single material.
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Affiliation(s)
- Ilenia Viola
- National Nanotechnology Laboratory of INFM-CNR, Distretto tecnologico ISUFI, Via Arnesano, Lecce, Italy. ilenia.viola2unile.it
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14
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Cirmi G, Brida D, Gambetta A, Piacenza M, Sala FD, Favaretto L, Cerullo G, Lanzani G. Observation and control of coherent torsional dynamics in a quinquethiophene molecule. Phys Chem Chem Phys 2010; 12:7917-23. [DOI: 10.1039/c000505c] [Citation(s) in RCA: 11] [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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15
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Zugazagoitia JS, Almora-Díaz CX, Peon J. Ultrafast Intersystem Crossing in 1-Nitronaphthalene. An Experimental and Computational Study. J Phys Chem A 2008; 112:358-65. [DOI: 10.1021/jp074809a] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Jimena S. Zugazagoitia
- Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, 04510, México, D.F., México
| | - César Xavier Almora-Díaz
- Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, 04510, México, D.F., México
| | - Jorge Peon
- Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, 04510, México, D.F., México
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16
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Piacenza M, Zambianchi M, Barbarella G, Gigli G, Della Sala F. Theoretical study on oligothiophene N-succinimidyl esters: size and push–pull effects. Phys Chem Chem Phys 2008; 10:5363-73. [DOI: 10.1039/b803963a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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17
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Uğurlu G, Kasap E, Kantarci Z, Bahat M. A theoretical study of the linear, nonlinear optical properties and conformational analysis of 3-phenylthiophene and its fluoro derivatives with torsional dependence. J Mol Struct 2007. [DOI: 10.1016/j.molstruc.2006.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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18
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Zade SS, Bendikov M. Twisting of Conjugated Oligomers and Polymers: Case Study of Oligo- and Polythiophene. Chemistry 2007; 13:3688-700. [PMID: 17299815 DOI: 10.1002/chem.200600819] [Citation(s) in RCA: 150] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Interring twisting (change in the dihedral angle between conjugated rings) of polythiophene was studied theoretically using periodic boundary conditions (PBC) at the B3LYP/6-31G(d) level. We find that the band gap of polymers is strongly dependent on the interring twist angle; yet twisting requires very little energy. A twist of 30 degrees increases the band gap by 0.75 eV in polythiophene, while requiring only 0.41 kcal mol(-1) per monomer unit. Such a small energetic value is of the order of crystal packing or van der Waals forces. These results are compared with calculations performed on model oligomers. Sexithiophene, its radical cations, and its dication are optimized at 0-180 degrees end-to-end twist angles (which correspond to 0-36 degrees interring dihedral angles) using the B3LYP/6-31G(d) method. The theoretical results suggest that the HOMO-LUMO gap, ionization potential, and charge distribution of oligomers are strongly dependent on twisting, whereas, similar to the case of polythiophene, twisting of neutral oligothiophenes costs very little energy. In the case of the radical cation, the lowest energy transition is shifted to a longer wavelength region on twisting, while the second-lowest energy transition is shifted to a shorter wavelength region. This implies that twisted, doped conducting polymers (modeled here by an oligomer radical cation), in contrast to planar, doped polymers, should be transparent within a certain optical window (in the far-visible region, at approximately 1.5 eV). This observation is explained on the basis of changes in the shape and overlap of the frontier molecular orbitals.
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Affiliation(s)
- Sanjio S Zade
- Department of Organic Chemistry, Weizmann Institute of Science, 76100 Rehovot, Israel
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19
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Piacenza M, Della Sala F, Fabiano E, Maiolo T, Gigli G. Torsional effects on excitation energies of thiophene derivatives induced by β-substituents: Comparison between time-dependent density functional theory and approximated coupled cluster approaches. J Comput Chem 2007; 29:451-7. [PMID: 17639501 DOI: 10.1002/jcc.20804] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The influence of methyl or phenyl substitution in beta-position of dioxygenated terthiophene and diphenylthiophene on the optical properties is investigated by first-principles calculations. We compare the approximated singles and doubles coupled cluster (CC2) approach with time-dependent density functional theory methods. CC2 reproduces experimental excitation energies with an accuracy of 0.1 eV. We find that the different substituents modify the inter-ring torsional angle which in turn strongly influences the excitation energies. The steric contribution to the excitation energies have been separated from the total substituent effects.
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Affiliation(s)
- M Piacenza
- National Nanotechnology Laboratory of INFM, Distretto Tecnologico ISUFI, Università degli Studi di Lecce, Via per Arnesano, I-73100 Lecce, Italy.
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20
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Fabiano E, Della Sala F, Barbarella G, Lattante S, Anni M, Sotgiu G, Hättig C, Cingolani R, Gigli G. Optical Properties of N-Succinimidyl Bithiophene and the Effects of the Binding to Biomolecules: Comparison between Coupled-Cluster and Time-Dependent Density Functional Theory Calculations and Experiments. J Phys Chem B 2006; 110:18651-60. [PMID: 16970495 DOI: 10.1021/jp062890w] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report a joint theoretical-experimental study on the optical properties of 5-N-succinimidyl-2,2'-bithiophene (NS-2T), a prototype system for a new class of biomarkers. Time-dependent density functional theory (TD-DFT) and approximate coupled-cluster single and doubles (CC2) calculations are performed in the ground and excited states. Theoretical results are compared with absorption, photoluminescence (PL), time-resolved PL, and PL quantum efficiency measurements. The excited state of NS-2T has a larger dipole moment as compared to that of the ground state, explaining the experimental shift of the PL peak in solvents of different polarity, and a smaller intersystem crossing (ISC) rate as compared to that of isolated bithiophene (2T), explaining the increased PL quantum efficiency. We also studied two model systems to describe the effects of the covalent binding of NS-2T to biomolecules and proteins with the epsilon-NH(2) lysine groups. These model systems show optical properties closer to 2T, as the PL quantum efficiency is reduced due to the increased ISC rate. Theoretical calculations and experimental results show that covalent binding of NS-2T to a biomolecule will blue-shift the absorption but not the photoluminescence. CC2 and TD-DFT can very well describe the absorption and photoluminescence energies of all three systems, but the presence of several charge-transfer transitions in the TD-DFT spectrum of NS-2T required the use of a correlated method to validate the TD-DFT results.
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Affiliation(s)
- E Fabiano
- National Nanotechnology Laboratory of INFM-CNR, Distretto Tecnologico, Università degli Studi di Lecce, Via per Arnesano, I-73100 Lecce, Italy
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21
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Lukes V, Pálszegi T, Milota F, Sperling J, Kauffmann HF. Density Matrix Analysis, Simulation, and Measurements of Electronic Absorption and Fluorescence Spectra of Spirobifluorenes. J Phys Chem A 2006; 110:1775-82. [PMID: 16451007 DOI: 10.1021/jp054507d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The linear absorption and fluorescence spectra as well as the oscillator strengths of 2,2',7,7'-tetraphenyl-9,9'-spirobifluorene (A), 2,2',7,7'-tetrakis(biphenyl-4-yl)-9,9'-spirobifluorene (B), and 2,2',7,7'-tetrakis(9,9'-spirobifluoren-2-yl)-9,9'-spirobifluorene (C) are calculated on the basis of the collective electronic oscillator (CEO) approach of Mukamel et al. (see, e.g., Chem. Rev. 2002, 102, 3171). The graphical visualization and quantitative characterization of CEO modes allows one to extract the real-space distribution of electronic excitations of the molecules under study. Effects of the lengthening and branching of the oligophenylene segments have been analyzed. The influence of the lowest excited (S1) vs ground-state (S0) geometry changes on the CEO modes is investigated and related to the geometry changes of the molecular parts. The obtained theoretical results are in good agreement with experimental trends observed in absorption and fluorescence data.
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Affiliation(s)
- Vladimir Lukes
- Department of Chemical Physics, Slovak University of Technology, Radlinského 9 SK-812 37 Bratislava, Slovakia.
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22
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Rubio M, Merchán M, Ortí E. A Theoretical Study on the Low-Lying Excited States of 2,2′:5′,2′′-Terthiophene and 2,2′:5′,2′′:5′′,2′′′-Quaterthiophene. Chemphyschem 2005; 6:1357-68. [PMID: 15942967 DOI: 10.1002/cphc.200400487] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The nature and properties of the low-lying singlet and triplet valence excited states of 2,2':5',2''-terthiophene (terthiophene) and 2,2':5',2'':5'',2'''-quaterthiophene (tetrathiophene) are discussed on the basis of high-level ab initio computations. The spectroscopic features determined experimentally for short alpha-oligothiophenes are rationalised on theoretical grounds. Special attention is devoted to the nonradiative decay process through intersystem crossing (ISC) from the singlet to the triplet manifold, which is known to be relatively less efficient in tetrathiophene. Along the geometry relaxation of the S1 state of terthiophene, the S1 and T2 states become degenerate, which leads to a favourable situation for the occurrence of ISC. The parallel process is expected to be less favoured in tetrathiophene because of the less efficient spin-orbit coupling and the increase of the S1-T2 energy gap.
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Affiliation(s)
- Mercedes Rubio
- Instituto de Ciencia Molecular, Universitat de València, Dr. Moliner 50, Burjassot, 46100 Valencia, Spain.
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23
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Anni M, Della Sala F, Raganato MF, Fabiano E, Lattante S, Cingolani R, Gigli G, Barbarella G, Favaretto L, Görling A. Nonradiative Relaxation in Thiophene-S,S-dioxide Derivatives: The Role of the Environment. J Phys Chem B 2005; 109:6004-11. [PMID: 16851655 DOI: 10.1021/jp046465j] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intramolecular radiative and nonradiative relaxation processes of three thiophene-S,S-dioxide derivatives with different molecular rigidity are investigated in different solutions and in inert matrix. We show that the fluorescence quantum efficiency and the relaxation dynamics are strongly dependent on the environment viscosity, whereas they are almost independent of the environment polarity. We demonstrate that this strong dependence is due to an environment dependent nonradiative decay rate, whereas no relevant variations of the radiative decay rate are observed. We demonstrate that the dipole coupling with the solvent does not provide an efficient nonradiative decay channel and that the S(n) - S(1) vibrational relaxation is very efficient in all of the molecules and for all of the investigated environments. Moreover first-principles time-dependent density-functional theory calculations in the correct, i.e., excited-state, molecular conformation, suggest that significant contributions of intersystem crossing to the triplet manifold can be excluded. We then conclude that the main nonradiative process determining the fluorescence quantum efficiency of this class of molecules is S(1) - S(0) internal conversion (IC). An explanation for the IC rate dependence in terms of the environment viscosity, molecular rigidity, S(1) - S(0) energy-gap, and molecular volume is presented.
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Affiliation(s)
- M Anni
- National Nanotechnology Laboratory (NNL) of INFM, Dipartimento di Ingegneria dell'Innovazione, Università degli Studi di Lecce, Via per Arnesano, 73100 Lecce, Italy
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Brustolon M, Barbon A, Bortolus M, Maniero AL, Sozzani P, Comotti A, Simonutti R. Dynamics of Alkoxy−Oligothiophene Ground and Excited States in Nanochannels. J Am Chem Soc 2004; 126:15512-9. [PMID: 15563180 DOI: 10.1021/ja046804m] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two oligothiophenes, 4,4'-dipentoxy-2,2'-dithiophene and 4,4"-dipentoxy-2,2':5',2":5",2' ''-tetrathiophene, have been included in the nanochannels of the autoassembling host TPP (tris-o-phenylenedioxycyclotriphosphazene). The effect of the confinement on the structure and properties of the two dyes, as conformational arrangements, dynamics, and photophysical behavior, was addressed by the combination of high spinning speed solid-state NMR and time-resolved EPR spectroscopy. We compared the conformations of the dyes in their ground and photoexcited triplet states and described in detail the dynamics of the supramolecular adducts from 4 K to room temperature. Above 200 K surprisingly fast spinning rates of the dithiophene core were discovered, while the side chains show far slower reorientation motion, being in bulky gauche-rich conformations. These lateral plugs keep the planar core as appended in the space like a nanoscale gyroscope, allowing a reorientation in the motion regime of liquids and a long triplet lifetime at unusually high temperature. The nuclear magnetic properties of the guest dyes are also largely affected by the aromatic rings of the neighboring host, imparting an impressive magnetic susceptibility effect (2 ppm proton shift). The high mobility is due to the formation of a nanocage in a channel where aliphatic and aromatic functions isolate the thiophene moieties. Instead, two conformers of the tetrathiophene twisted on the central bond are stabilized by interaction with the host. They interconvert fast enough to be averaged in the NMR time scale.
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Affiliation(s)
- Marina Brustolon
- Department of Chemical Sciences, University of Padua, and INSTM, UdR of Padua, Via Marzolo 1, 35131 Padua, Italy.
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Raganato MF, Vitale V, Della Sala F, Anni M, Cingolani R, Gigli G, Favaretto L, Barbarella G, Weimer M, Görling A. The effects of oxygenation on the optical properties of dimethyl-dithienothiophenes: Comparison between experiments and first-principles calculations. J Chem Phys 2004; 121:3784-91. [PMID: 15303947 DOI: 10.1063/1.1775782] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Modifications of the optical properties of dimethyl-dithienothiophenes due to the oxygen functionalization of the central sulfur atom are investigated. We have measured the absorption, photoluminescence (PL) and PL excitation spectra, the PL quantum efficiencies, and the PL decay times. These experimental results are interpreted and compared with first-principles time-dependent density-functional theory calculations, which predict, for the considered systems, excitation and emission energies with an accuracy of 0.1 eV. It is found that the oxygenation strongly changes optical and photophysical properties. These effects are related to the modifications of the energetically lowest-unoccupied molecular orbital and the energetically second highest occupied one, which change the relative position of the two lowest singlet and triplet excited states.
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Affiliation(s)
- M F Raganato
- National Nanotechnology Laboratory of INFM, Distretto Tecnologico, Universita degli Studi di Lecce, Via per Arnesano, I-73100 Lecce, Italy
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Tedesco E, Della F, Favaretto L, Barbarella G, Albesa-Jové D, Pisignano D, Gigli G, Cingolani R, Harris KDM. Solid-State Supramolecular Organization, Established Directly from Powder Diffraction Data, and Photoluminescence Efficiency of Rigid-Core Oligothiophene-S,S-dioxides. J Am Chem Soc 2003; 125:12277-83. [PMID: 14519013 DOI: 10.1021/ja035570o] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The "rigid-core" material 3,5-dimethyl-2,3'-bis(3-methylthiophene)-dithieno[3,2-b:',3'-d]thiophene-4,4-dioxide (DTTOMe4) has the highest photoluminescence ever reported for thiophene-based molecules in the solid state. We report the structure of this material, determined directly from powder X-ray diffraction data using the Genetic Algorithm method for structure solution, followed by Rietveld refinement, and the structural properties are discussed in relation to the structures of the corresponding subsystems DTTO and DTTOMe. While the crystal structures of the latter compounds contain cofacial dimers, the crystal structure of DTTOMe4 comprises layers of molecules aligned in an antiparallel fashion. Intermediate neglect of differential overlap with single configuration interaction (INDO/SCI) calculations on the intermolecular interactions in the three crystal structures show that the different solid-state photoluminescence efficiencies of DTTOMe4, DTTOMe, and DTTO cannot be correlated with the different types of dipole-dipole alignment in the solid state. Instead, photoluminescence efficiencies correlate well with the rate of formation of nonradiatively decaying charge-transfer pairs upon photoexcitation. Because of larger intermolecular distances in DTTOMe4, the photoluminescence is less effectively quenched by charge-transfer processes than in DTTOMe and DTTO.
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Affiliation(s)
- Emilio Tedesco
- School of Chemical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
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Lukeš V, Breza M, Biskupič S. Structure and electronic properties of bithiophenes. I. Torsional dependence. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0166-1280(02)00429-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Meinardi F, Cerminara M, Sassella A, Borghesi A, Spearman P, Bongiovanni G, Mura A, Tubino R. Intrinsic excitonic luminescence in odd and even numbered oligothiophenes. PHYSICAL REVIEW LETTERS 2002; 89:157403. [PMID: 12366021 DOI: 10.1103/physrevlett.89.157403] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2002] [Indexed: 05/23/2023]
Abstract
The emission properties of crystalline oligothiophenes (OTs) are investigated and related to the different selection rules arising from the number of rings. In odd OT crystals the purely electronic emission is absent since the molecular A1-1B(1) transition dipoles cancel at the bottom of the excitonic band. On the contrary, in crystals of even OTs this transition is allowed due to the constructive interference of the off-axis components of the molecular transition dipole. It possesses a polarization in the herringbone plane and exhibits superradiant behavior.
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Affiliation(s)
- F Meinardi
- INFM and Department of Material Science, University of Milano-Bicocca, via Cozzi 53, Italy
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Lukeš V, Breza M, Laurinc V. Structure dependence of optical properties of bridged bis-thienyls. I. Simple five-membered aromatic bridges. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s0166-1280(01)00785-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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