DFT calculations of the local spin densities and oligomerization mechanism of thiophene–phenylene (TP) co-oligomers and derivatives

Zgou, H.; Hamidi, Mohamed; Bouachrine, Mohammed

doi:10.1016/j.theochem.2007.02.043

Cited by 16 publications

(6 citation statements)

References 27 publications

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“…42 This can be compared to crystallographically obtained torsion angles between a thiophene and a phenyl ring that range from 7.2°4 3 to 26.8°4 4 depending on the chemical environment and packing, whereas DFT-calculated angles in the gas phase for such a system vary between 14.0°4 5 and 21.8°. 46 Considering the structural ordering in oligomers, quinoxaline groups from neighboring monomers can point in approximately the same direction, as shown for the TQ1 dimer in Figure 1, if both involved dihedral angles (φ 1 and φ 2 ) are small (cis conformation) or both dihedral angles are large, ∼180°(cis2, see Figure S2, Supporting Information). Alternatively, neighboring quinoxaline groups point roughly in opposite directions (trans, see Figure S2, Supporting Information) if one of the two dihedral angles is small and the other is large.…”

Section: ■ Resultsmentioning

confidence: 86%

Quantum Chemical Calculations of Side-Group Stacking and Electronic Properties in Thiophene–Quinoxaline Polymers

Hedström

Persson

2012

J. Phys. Chem. C

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Organic bulk heterojunction (BHJ) solar cells offer a viable source of solar energy. Structural organization is crucial in BHJ cells but hard to achieve and assess due to limitations in experimental methodology. Quantum chemical methods have here been used to gain further insight into the geometric and optical properties of a promising light-harvesting polymer, poly[2,3-bis(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1). Calculations show that favorable positions of the two alkoxyphenyl side groups on each TQ1 monomer allow nonbonded side-group stacking interactions with the neighboring units in both directions. This yields a unique, helical geometry with enhanced intramolecular ordering that promotes extensive electronic conjugation. Adequate description of this effect requires computational methods that include dispersion corrections. A strategy based on such side-group interactions is proposed for designing new polymers.

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Section: ■ Resultsmentioning

confidence: 86%

Quantum Chemical Calculations of Side-Group Stacking and Electronic Properties in Thiophene–Quinoxaline Polymers

Hedström

Persson

2012

J. Phys. Chem. C

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“…To prevent a serious aggregation of polymers, we introduced a tilted polymer backbone consisting of repetitive phenylene and thiophene units as well as branched side chains. − Because torsional angles along the main chain have a great effect on the intermolecular packing and PL quenching, the polymer chain conformation was modulated to optimize the π-conjugation and exciton migration with minimized ACQ. The incorporation of the phenylene moieties in a polymer backbone breaks the chain planarity of polythiophenes and avoids a serious intermolecular packing. , The energy-minimum conformational analysis of PPDT-P was performed by density functional theory calculation (basis set: B3LYP/6-31g(d,p)) (Figure S2). By introducing the phenylene units in a polymer backbone, torsional angles between thiophene and phenylene (Φ 1 , Φ 2 , Φ 5 , and Φ 6 ) moieties were calculated to be ∼24°, leading to a twisted backbone.…”

Section: Results and Discussionmentioning

confidence: 99%

“…The incorporation of the phenylene moieties in a polymer backbone breaks the chain planarity of polythiophenes and avoids a serious intermolecular packing. 31,32 The energy-minimum conformational analysis of PPDT-P was performed by density functional theory calculation (basis set: B3LYP/6-31g(d,p)) (Figure S2). By introducing the phenylene units in a polymer backbone, torsional angles between thiophene and phenylene (Φ 1 , Φ 2 , Φ 5 , and Φ 6 ) moieties were calculated to be ∼24°, leading to a twisted backbone.…”

Section: Preparation and Optimization Of Fret-basedmentioning

confidence: 99%

Green-, Red-, and Near-Infrared-Emitting Polymer Dot Probes for Simultaneous Multicolor Cell Imaging with a Single Excitation Wavelength

et al. 2020

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We report newly synthesized fluorescence resonance energy transfer (FRET)-based green-, red-, and near-infrared (NIR)-emitting polymer dot (Pdot) probes. Fluorescent Pdots (∼60 nm) were prepared with a green-emissive conjugated polymer (PPDT-P, donor) alone or mixing the donor with a red-or NIRemitting fluorophore (T-DCS or ITIC, acceptor), where an optically inert matrix polymer [poly(styrene-co-maleic anhydride)] was mixed together to minimize the aggregation-caused quenching by diluting the fluorophores and surface functionalization for further bioconjugation with antibodies for active targeting. Highly fluorescent green-emissive PPDT-P Pdots were prepared with a photoluminescence (PL) quantum efficiency of ∼30% and the FRETmediated red and NIR PL was intensified by 5.3−8.5 times (with high FRET ratios of ∼9) via the efficient energy transfer (FRET efficiency of 80−98%) and antenna effect, compared with the signals obtained via direct excitation of the fluorophores in Pdots. All three types of Pdot/antibody conjugates were simultaneously immunostained to COS-7 cells (showing minimal cross-reactivity), reducing the tedious sequential immunostaining process to a single step. Finally, we obtained high-contrast three-color cell images with little spectral leakthrough by exciting all the probes simultaneously at a single wavelength at 405 nm without the need for a complicated or expensive multiple-excitation setup.

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“…The electron density of LUMO is mainly localized on the thienyl-phenyl rings of each compound and it is π*-bonding orbitals. Thus, the frontier orbital spreads over the whole π-conjugated backbone in the oligomer O3 [33,34]. Therefore, ߨ-electron delocalization on the carbazole unit will be neglected.…”

Section: Frontier Molecular Orbitalsmentioning

confidence: 99%

A DFT study of charge-transfer and opto-electronic properties of some new materials involving carbazole units

Hlel

Mabrouk

Chemek

et al. 2015

Computational Condensed Matter

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DFT calculations of the local spin densities and oligomerization mechanism of thiophene–phenylene (TP) co-oligomers and derivatives

Cited by 16 publications

References 27 publications

Quantum Chemical Calculations of Side-Group Stacking and Electronic Properties in Thiophene–Quinoxaline Polymers

Quantum Chemical Calculations of Side-Group Stacking and Electronic Properties in Thiophene–Quinoxaline Polymers

Green-, Red-, and Near-Infrared-Emitting Polymer Dot Probes for Simultaneous Multicolor Cell Imaging with a Single Excitation Wavelength

A DFT study of charge-transfer and opto-electronic properties of some new materials involving carbazole units

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