From Rigorous Standards to Student Achievement

Santos, Karen

doi:10.4324/9781315852669

Cited by 3 publications

(5 citation statements)

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“…On the basis of their application in organic electronic devices as well as versatile chemistry, thiophene-related oligomers, and polymers have remained one of the most well-studied p-conjugation systems in the past few decades [11,12]. Many of substituted derivatives have been designed and synthesized, and their electronic properties have been studied too.…”

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First principles investigation on the key factors of broad absorption spectra and electronic properties for oligothiophene and its derivatives for solar cells

Tang

Zhang

2011

Int J of Quantum Chemistry

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On the basis of optimized structures of two kinds thiophene oligomers, we investigated the configuration and conformation dependent optical and electronic properties of a or b substituted oligothiophene (PT) and oligo(thienylenevinylene) (PTV) isomers, respectively, at the TD-DFT/6-31þG(d,p)//PBE0/6-31G(d) level. The corresponding properties of polymers were predicted by extrapolation method. The broad absorption regions for polythiophene and/or poly(thienylenevinylene) can be ascribed to the coexistence of various conformational and/or configurational isomers with similar energies and each corresponding excited state possessing different absorption spectrum and overlapping each other. Furthermore, the reorganization energies for electron (k e ) and hole (k h ) of a or b substituted PTV and PT indicate them to be potential ambipolar charge transport materials under the proper operating conditions. Therefore, these results are important because they can provide a rational way for the design of multifunctional materials with broad absorption and ambipolar charge transport properties for solar cells devices.

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confidence: 99%

First principles investigation on the key factors of broad absorption spectra and electronic properties for oligothiophene and its derivatives for solar cells

Tang

Zhang

2011

Int J of Quantum Chemistry

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“…This result lets us believe that the formation of PMeT main chain is created by the 2 or 5 coupling. In fact, it was shown that FeCl 3 generates essentially polymerization by two to five coupling and not by two to four coupling 33. In addition, it is known that the polymerization with FeCl 3 leads in general to irregular poly(alkylthiophene) and approximately 70 to 80% of regular Head to Tail coupling is generated 33.…”

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confidence: 99%

“…In fact, it was shown that FeCl 3 generates essentially polymerization by two to five coupling and not by two to four coupling 33. In addition, it is known that the polymerization with FeCl 3 leads in general to irregular poly(alkylthiophene) and approximately 70 to 80% of regular Head to Tail coupling is generated 33. Based on NMR and XRD results,13 the PMeT main chain in the synthesized copolymer is region‐random and we estimate the regioregularity with a 70 to 80% of HT coupling.…”

Section: Resultsmentioning

confidence: 99%

“…The high inter‐ring torsion is detected essentially between the two carbazole units forming the bicarbazole unit (ϕ 1 = −39.0°), and between the two non regular Tail to Tail coupled methylthiophene (ϕ 5 = 56.4°). In fact, it is known that a regular coupling HT‐HT of thiophene rings induces a planar structure, while the presence of irregular coupling generates a distortion in the main chain, inducing a non planar structure and then a decrease on the effective conjugation length 33…”

Section: Resultsmentioning

confidence: 99%

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A theoretical investigation on the properties of the new poly(N‐vinylcarbazole)‐3‐methylthiophene (PVK‐3MeT) synthesized graft copolymer

Chemek

Ayachi

Hlel

et al. 2011

J of Applied Polymer Sci

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ABSTRACT:In this article, we present quantum chemical calculations, based on density functional theory (DFT), performed to investigate the geometries and the opto-electronic properties of a new synthesized graft copolymer based on poly(N-vinylcarbazole) (PVK) and poly(3-methylthiophene) (PMeT) named PVK-3MeT. First, we have theoretically computed and compared the structural, optical, and vibrational parameters of both neutral and doped states. In addition, the excited state was theoretically obtained by the ab initio RCIS/ STO-3G method. To assign the absorption and emission peaks observed experimentally, we computed the energies of the lowest singlet excited state with the time-dependent density functional theory (TD-DFT) method. Electronic parameters such as the HOMO-LUMO band gap, the ionization potential (IP), and electron affinity (EA) are extracted. Calculations show that the PVK-3MeT copolymer is nonplanar in its ground neutral state. Meanwhile, upon doping or photoexcitation, an enhancement of the planarity is observed, resulting on a decrease of the inter-ring torsion angle between 3-methylthiophene units. Such modifications in the geometric parameters induce a dramatic change on the HOMO and LUMO orbitals in the doped or excited states.

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“…The control of medically important mollusks has remained an essential component of integrated control programs, but chemical molluscicides are expensive, the application process is complex, and their use can generate major impacts and lethal effects on other organisms due to the lack of selective action [16,[54][55][56][57]. In this respect, it is worth mentioning that specimens of S. marmorata, notified by ICMBio as an endangered species, would run the risk of having reduced populations within such interventions of snail control, as recently recommended by the WHO [58,59].…”

Section: Discussionmentioning

confidence: 99%

Survey on Limnic Gastropods: Relationships between Human Health and Conservation

et al. 2022

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The present work aimed to study ecological aspects related to the distribution pattern of medically important and native freshwater mollusks, found in a rural municipality in the state of Minas Gerais, Brazil. Malacological captures were carried out in aquatic environments (lentic and lotic) from 46 locations between October 2018 and September 2019. The collected specimens were subjected to taxonomic identification and evaluation for infection with trematode larvae. Qualitative data were used to analyze the similarity and the odds ratios between the environmental variables. In total, 1125 specimens were sampled, belonging to the following species: Biomphalaria glabrata, B. tenagophila, B. straminea, B. kuhniana, B. cousini, Biomphalaria sp., and Drepanotrema cimex (Planorbidae), Stenophysa marmorata (Physidae), Omalonyx sp. (Succineidae), Pseudosuccinea columella (Lymnaeidae), and Pomacea sp. (Ampullaridae). Echinostome, strigeocercaria, and xiphidiocercaria types of larval trematodes were detected in S. marmorata and D. cimex. Of note was the similarity in the distribution of S. marmorata, a supposedly endangered species, with that of the medically important Biomphalaria species, with the two sharing environments. This complex scenario led us to reflect on and discuss the need for the control of important intermediate hosts, as well as the conservation of endangered species. This relevant issue has not yet been discussed in detail, in Brazil or in other countries that recommend snail control.

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From Rigorous Standards to Student Achievement

Cited by 3 publications

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First principles investigation on the key factors of broad absorption spectra and electronic properties for oligothiophene and its derivatives for solar cells

First principles investigation on the key factors of broad absorption spectra and electronic properties for oligothiophene and its derivatives for solar cells

A theoretical investigation on the properties of the new poly(N‐vinylcarbazole)‐3‐methylthiophene (PVK‐3MeT) synthesized graft copolymer

Survey on Limnic Gastropods: Relationships between Human Health and Conservation

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