Molecular properties of coordination compounds of the croconate ion with first-row sivalent transition metals: a quantum mechanical study

Ferreira, Dalva E. C.; Santos, Hélio F. Dos; Almeida, Wagner B. De; Junqueira, Geórgia M. A.

doi:10.1590/s0103-50532007000700014

Cited by 5 publications

(9 citation statements)

References 40 publications

(66 reference statements)

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“…The first hyperpolarizability of organic molecules is strongly correlated with the size of the alternated conjugation of the bridge group linking the D – A pair as well as the nature and strength of the donor–acceptor pair 2, 3, 24, 77, 86. We analyzed both features using appropriate molecular descriptors.…”

Section: Resultssupporting

confidence: 63%

“…From the tensor elements β ijk , the Cartesian components β x , β y , and β z can be calculated according to eq 1: Thus, the total molecular first hyperpolarizability (β mol ) is calculated according to eq 2. As explained in ref 77,. the Gaussian quantum mechanical package78 uses the relationship β ij = β ji and provides a tensor with only 10 elements.…”

Section: Computational Aspectsmentioning

confidence: 99%

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Donor–acceptor diethynylsilane oligomers: A second‐order nonlinear optical material

Machado

Souza

Santos

et al. 2011

J Polym Sci B Polym Phys

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The interest in the study of oligomers has been motivated mainly because of their solubility in common solvents and also their capacity to be crystallized, which allowed for chemical processing leading to important applications in the area of material sciences. In this work, we carried out an investigation of polydiethynylsilane (PDES) decamers substituted with electron donor (D) and acceptor (A) groups, which is certainly of relevance, once PDES itself is known to display large third‐order optical susceptibility. Therefore, density functional theory calculations of static first hyperpolarizability (β) were performed using various functionals with the 6‐31G(d) basis set along with correlated MP2 calculation used as reference for comparison. The influence of A and D substituents on the magnitude of β was investigated by matching the acceptor (dicyanovinyl, nitrobenzene) and donor (propyl, propoxy, and phenylamine) groups attached at both ends of the oligomer. The largest β value was predicted for the derivative having the phenylamine and dicyanovinyl groups, which is around 30 times the relative value for the nonsubstituted decamer, what is a very impressive enhancement reported for the first time in the literature, strongly suggesting that disubstituted diethynylsilane decamers are potential building blocks for molecular‐based materials with second‐order nonlinear responses. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1410–1419, 2011

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Section: Resultssupporting

confidence: 63%

Section: Computational Aspectsmentioning

confidence: 99%

Donor–acceptor diethynylsilane oligomers: A second‐order nonlinear optical material

Machado

Souza

Santos

et al. 2011

J Polym Sci B Polym Phys

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“…Estas são grandezas tensoriais, sendo a primeira hiperpolarizabilidade (β) um tensor com 27 componentes β ijk (i, j, k = x, y, z). 43 Geralmente, os elementos diferentes de zero são reduzidos em função de aspectos de simetria. 44 Nos cálculos PM3, como implementado no programa MOPAC-07, β ijk = β ikj , fornecem, portanto, 18 componentes distintas do tensor.…”

Section: (1)unclassified

Estudo teórico de propriedades ópticas não-lineares de nanotubos de carbono de parede única quimicamente modificados

et al. 2009

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Estudo tEórico dE propriEdadEs ópticas não-linEarEs dE nanotubos dE carbono dERecebido em 29/1/08; aceito em 10/9/08; publicado na web em 2/2/09 THEORETICAL ANALYSIS OF NON-LINEAR OPTICAL PROPERTIES FOR CHEMICALLY MODIFIED SINGLE WALL CARBON NANOTUBES. Structure and first hyperpolarizability for a series of armchair a(5,5) chemically modified carbon nanotubes (CNT) were calculated at semiempirical and density functional levels of theory. The 4,4´-substituted stilbenes were selected as chromophore with substituents at position 4´ set to X=NO 2 , H, Cl, OH and NH 2 . The calculated values for static first hyperpolarizability (β) were almost linearly dependent on the electronic effect of the group X, increasing from NO 2 to NH 2 . At DFT level the effect of inserting the chromophore in the CNT surface was to enhance the β value up to 70% relative to the free 4,4´-substituted stilbene.Keywords: SWNT; NLO; ab-initio. introduÇãoDescobertos em 1991 por Sumio Iijima, 1 os nanotubos de carbono (CNTs) vêm sendo objeto de um extensivo número de trabalhos, sob diversas abordagens, tanto teóricas 2-4 quanto experimentais. 5-7 Tratase de uma forma alotrópica do carbono, na qual arranjos hexagonais destes átomos, com hibridização nominal sp 2 , se dispõem ao longo de superfícies cilíndricas de diâmetros da ordem de nanômetros e comprimentos da ordem de micrômetros.8 Podem ser observadas estruturas de múltiplas camadas concêntricas (MWNTs) ou estruturas de uma única camada (SWNTs), sendo que as extremidades podem ser constituídas por formas semi-esféricas (hemi-fulerenos), formas cônicas ou poliédricas.9 Para melhor entendimento das estruturas, utiliza-se um modelo no qual se admite que cada camada dos tubos corresponda a uma folha de grafeno envolta a uma direção axial. . As grandezas (n, m), denominadas índices de Hamada, definem a direção deste vetor, tomado em relação à folha de grafeno, podendo-se dividir as estruturas de acordo com esta direção em três tipos: armchair (n = m), zig-zag (n, m = 0) e quiral (n ¹ m) com n > m > 0. O vetor translação, ortogonal ao vetor quiral, indica a direção axial dos tubos, na qual as estruturas podem ser formadas através da projeção de suas respectivas celas unitárias. 10A busca de relações entre estrutura e propriedades tem sido significativamente avaliada para nanotubos de carbono, visando possíveis aplicações destes em diversas áreas da ciência.11 Um exemplo químico de relação estrutura-propriedade pode ser verificado na reatividade de tais espécies, que é dependente de dois fatores:12 ângulo de piramidalização (q p = (q sp -90) 0 , onde q sp é o ângulo compreendido entre um orbital s e um orbital p em um mesmo átomo de carbono) e ângulo de "falta de alinhamento" (missaligment) (ângulo entre dois orbitais p presentes em átomos de carbono adjacentes). Ambos os fatores variam inversamente com o diâmetro dos tubos e é esperado que tubos de menor diâmetro sejam mais reativos que tubos de maior diâmetro. Sendo as propriedades dependentes da estrutura, pode-se supor que a modificação raciona...

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“…The general conclusion is that the aromaticity decreases with the ring size 9. The literature on oxocarbons 1–24 is extensive with some important theoretical studies 12–22. In our group, we have previously used quantum mechanical methods and Monte Carlo simulations to study the behavior of the oxocarbon ions and their coordination compounds in the gas phase and in aqueous solution 14–19.…”

Section: Introductionmentioning

confidence: 99%

“…Besides the interesting chemical physics aspects of these species that have motivated many studies, some applications have also been reported 11, 25, 26. The oxocarbon derivatives have been used as photoreceptors and their nonlinear optical (NLO) properties have been studied experimentally 25, 26 and theoretically 12, 13, 21. NLO is related to the interaction of applied electromagnetic fields in suitable materials to generate new fields with distinct frequencies, phase, or other physical properties 27, 28.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of nonlinear optical properties of oxocarbon derivatives

Junqueira

Faria

Silva

et al. 2009

Int J of Quantum Chemistry

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ABSTRACT:In this work, first hyperpolarizability (β) and electronic spectra were obtained at ab initio and semiempirical levels of theory for mono-and bi-squarate derivatives. The results from our calculations suggest the investigated compounds as potential molecules for nonlinear optics (NLO). By means of the employed theoretical methodology, it was possible to identify structural aspects leading to enhancement of the NLO properties of the studied oxocarbons. Furthermore, a correlation between Hammett parameters of the substituents ( σ p ) and ln(β tot ) was established.

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Molecular properties of coordination compounds of the croconate ion with first-row sivalent transition metals: a quantum mechanical study

Cited by 5 publications

References 40 publications

Donor–acceptor diethynylsilane oligomers: A second‐order nonlinear optical material

Donor–acceptor diethynylsilane oligomers: A second‐order nonlinear optical material

Estudo teórico de propriedades ópticas não-lineares de nanotubos de carbono de parede única quimicamente modificados

Theoretical study of nonlinear optical properties of oxocarbon derivatives

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