Investigation of NLO properties of substituted (<i>M</i>)‐tetrathia‐[7]‐helicenes by semiempirical and DFT methods

Daul, Claude; Ciofini, Ilaria; Weber, Valéry

doi:10.1002/qua.10444

Cited by 38 publications

(20 citation statements)

References 26 publications

(27 reference statements)

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“…Three pyridine-pyrimidine units make slightly more than one helical turn so that the structure does not exactly exhibit C 3 symmetry. A similar situation was found for the helicenes and heliphenes, with a noticeable difference for the (approximate) number of units per helical turn: three for the pyridine-pyrimidine oligomers, but six for the helicenes and heliphenes [19] although the number of aromatic rings is similar. Further information about the relationship between the chemical motif and the number of units per helical turn can be found in the works by Huc and collaborators.…”

Section: Resultssupporting

confidence: 68%

“…[10][11][12] Among these systems, conjugated helical molecules composed of ortho-fused aromatic rings, called (homo-or hetero-) helicenes, have been extensively studied, both experimentally [13][14][15][16][17][18] and theoretically. [19][20][21] In particular, strategies have been proposed to enhance their secondorder NLO responses. Chiral induction and amplification mechanisms have also been studied in a variety of (helical) polymers bearing chiral groups [22] as well as in chiral columnar stacks of C 3 -symmetry molecules.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Investigation of the Second‐Order Nonlinear Optical Properties of Helical Pyridine–Pyrimidine Oligomers

Botek

Castet

Champagne

2006

Chemistry A European J

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The structure and second-order nonlinear optical properties of a series of helical pyridine-pyrimidine oligomers recently synthesized by Barboiu and Lehn have been investigated theoretically by combining molecular mechanics and quantum chemistry approaches. In the absence of substituents, the hyper-Rayleigh scattering response (betaHRS) and the projection of the first hyperpolarizability on the dipole moment (beta||) exhibit periodic variations with chain length, but these nonlinear optical responses remain small. The first hyperpolarizabilities can, however, be enhanced by adding substituents. The greatest enhancement is obtained by substituting the pyrimidine groups by donor groups. Moreover, regular distributions of the donor groups around the helices enable the design of supramolecular structures exhibiting dipolar, octupolar or Lambda-shaped nonlinear optical characters, evident from the values of the depolarization ratios in hyper-Rayleigh scattering. Therefore this theoretical investigation demonstrates the potential of helical structures for the organization of chromophores in such a way that they exhibit large and specific second-order nonlinear optical responses.

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Section: Resultssupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Theoretical Investigation of the Second‐Order Nonlinear Optical Properties of Helical Pyridine–Pyrimidine Oligomers

Botek

Castet

Champagne

2006

Chemistry A European J

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“…[3][4][5][6] Moreover, as chirality can lead to noncentrosymmetric macroscopic arrangements, helicenes are good candidates for nonlinear optics (NLO), 7,8 and their structures can be modified by appropriate substitutions with donor and acceptor groups to show large second-order NLO responses at both the microscopic and macroscopic levels. [9][10][11][12][13][14] Moreover, their large two-photon circular dichroism 15 has recently been investigated by theoretical means.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Raman optical activity of π‐conjugated helical systems: Hexahelicene and heterohelicenes

Liégeois¹,

Champagne²

2008

J Comput Chem

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Helicenes constitute a special class of molecules combining helical conformation with pi-electron delocalization. These confer to helicenes specific chirooptical properties. In this article, we investigate the vibrational signatures thanks to the simulation of vibrational Raman optical activity (VROA) spectra. For that, four representative helicenes: hexahelicene, tetrathia-[7]-helicene, and its pyrrole and furan analogs have been simulated and interpreted using a recently implemented analytical scheme. Helicenes show intense VROA peaks attributed to their pi-conjugated structure and associated with collective vibrational modes. In hexahelicene, the dominant VROA features are due to vibrational modes involving motions of the carbon skeleton and H-wagging, but the intensity finds its source almost exclusively in the former. In the case of the three heterohelicenes, the previous statement is also verified, and on changing the heteroatoms, similar modes presenting comparable atomic contribution patterns have been highlighted, though the vibrational and electronic properties are modified. Some fingerprints could therefore be associated with the helicity of the system. In particular, in forward spectra, most of the VROA bands are positive for left-handed helicenes. Nevertheless, the spectral patterns are quite complex, and no easy rule-of-thumb could distinguish between the different heterohelicenes. Then, considering the fact that most of the contributions originate from the C atoms (group coupling matrices decomposition), it can be concluded that the major role of the heteroatom is restricted to modifying the geometry and the normal modes. At last, the small impact of the gauge-origin on the calculated spectra using a relatively modest basis set (rDPS:3-21G) is demonstrated here in the case of the tetrathia-[7]-helicene molecule presenting a C(2) symmetry. This further demonstrates the adequacy of this basis set for VROA calculations.

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“…Studies show that tetrathia- [7]-helicene and their Ru(II) and Fe(II) complexes are good candidates for second-order NLO materials. 27,49 Quinoxaline (i.e., benzopyrazine) can be easily synthesized from diketones and diamines. 50 Quinoxaline has the strong electronwithdrawing ability, which originates from the two unsaturated nitrogen atoms in the pyrazine ring.…”

Section: Introductionmentioning

confidence: 99%

Photophysical properties of quinoxaline-fused [7]carbohelicene derivatives

Liu

Pan

et al. 2015

RSC Adv.

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Helicene and its derivatives have received much attention as the candidates of organic photoelectronic material. Recently, novel quinoxaline-fused [7]carbohelicene derivatives exhibit unique structural and photophysical properties, especially in the crystal states. However, their structure-property relationships have not been fully understood from the micromechanism, which is also important to further improve their performance. Here, the electronic transition, electronic circular dichroism (CD), second-order nonlinear optical (NLO) response and charge transport properties of five quinoxaline-fused [7]carbohelicene derivatives have been investigated based on density functional theory calculations. The experimental UV-Vis/CD spectra of the studied compounds were well reproduced by our calculations. Thus, we can assign their electron transition properties and absolution configurations (ACs) with high confidence. It is found that CD bands of quinoxaline-fused [7]carbohelicene derivatives mainly originate from exciton coupling between quinoxaline, phenyl or 4-methoxyphenyl and [7]carbohelicene, which is in sharp contrast to [7]carbohelicene. More interestingly, these derivatives possess large first hyperpolarizability values. For example, the βHRS value of compound 6 is 32.96 × 10 −30 esu, which is about 190 times larger than that of the organic urea molecule. The bandwidth of valence band of compound 2 is comparable to that of conduction band and slightly larger than that of tris(8-hydroxyquinolinato)aluminium. This means that compound 2 is the potential candidate as ambipolar charge transport material. Please do not adjust marginsPlease do not adjust margins modulates the LUMO energy level. As a consequence, LUMO energy of compound 2 is much lower than that of compound 1 (Table S6), which leads to the smaller energy gap (Eg) for compound 2. Moreover, the main electron transitions characters are of charge transfer from quinoxaline to [7]carbohelicene and vice versa (Fig. 3). On the basis of above analysis, it is found that involvement of quinoxaline unit not only modulates the electron absorption wavelength but also alter the electron transition property. Compounds 3 and 4 also exhibit four absorption bands, which is similar to those of compound 2. In other words, the substituent effect of phenyl or 4-methoxyphenyl group on the UV-Vis spectra of compound 2 is not great. It is noted that some of the molecular orbitals involved in these transitions partially located on the phenyl or 4-methoxyphenyl group. Fig. 2Calculated UV-Vis (left) and CD (right) spectra in gas phase of 1, 2, 3 and 4 at the TDB3LYP/6-31+G(d) level of theory along with the experimental spectra (red dashed line).

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Investigation of NLO properties of substituted (M)‐tetrathia‐[7]‐helicenes by semiempirical and DFT methods

Cited by 38 publications

References 26 publications

Theoretical Investigation of the Second‐Order Nonlinear Optical Properties of Helical Pyridine–Pyrimidine Oligomers

Theoretical Investigation of the Second‐Order Nonlinear Optical Properties of Helical Pyridine–Pyrimidine Oligomers

Vibrational Raman optical activity of π‐conjugated helical systems: Hexahelicene and heterohelicenes

Photophysical properties of quinoxaline-fused [7]carbohelicene derivatives

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