Synthesis of carbazole derived aza[7]helicenes

Upadhyay, Gourav M.; Talele, Harish R.; Sahoo, Sibaprasad; Bedekar, Ashutosh V.

doi:10.1016/j.tetlet.2014.07.116

Cited by 39 publications

(24 citation statements)

References 54 publications

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“…For the helical molecules it is established that the presence of the twist in the structure prevents such aggregate formation due to suppression of π-π stacking caused by rigidity of the shape of the molecules. In our earlier study 13 The synthesis of aza[n]helicene unit can be achieved by oxidative photocyclization of suitable styryl derivative of alkyl carbazole moiety. We have chosen to attach n-butyl group on the nitrogen of carbazole 1 in order to achieve reasonable solubility to the final azahelicenes and the intermediates.…”

Section: Resultsmentioning

confidence: 99%

“…Aromatic systems with extended π-conjugation and with flat structure show different optical properties as compared to the similar systems with twisted structures. In the present study we have also compared these properties with structurally similar aza[7]helicene 9 synthesized earlier 13. The UV-Vis spectra of bi-aza[5]helicene 7 and biaza[6]helicene 8, along with 9, in dichloromethane exhibit absorption bands in the range of 262 to 337 nm.…”

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confidence: 87%

“…Although considerable attention has been devoted to the thia-helicenes, 7 the aza-M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 3 this type of aza [7]helices. 13 Another pyrrolo [5]helicene V system was reported by Hassine et al 14 which consisted of an unsymmetric unit of carbazole. Recently List and co-workers 15 have efficiently synthesized bis-azahelicene VI, along with other derivatives with an efficient use of organocatalysts for double Fischer indolization-oxidation protocol.…”

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confidence: 97%

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Synthesis and photophysical properties of bi-aza[5]helicene and bi-aza[6]helicene

Upadhyay

Bedekar

2015

Tetrahedron

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confidence: 99%

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confidence: 87%

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confidence: 97%

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Synthesis and photophysical properties of bi-aza[5]helicene and bi-aza[6]helicene

Upadhyay

Bedekar

2015

Tetrahedron

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“…The compounds belonging to the general class of oxa-helicenes and thia-helicenes have been synthesized, and their various properties have been studied [38][39][40][41][42][43][44][45]. Recently Sundar and Bedekar [46] reported the design and synthesis of oxygen-containing 7,12,17-trioxa [11] helicene.…”

Section: Introductionmentioning

confidence: 99%

Spectral and optoelectronic studies on 7,12,17-trioxa and 7,12,17-trithia [11] helicenes: a DFT view

Islam

Chimni

2017

Indian J Phys

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Density functional theory has been used to analyse the structural, spectral, charge transport and nonlinear properties of 7,12,17-trioxa [11] helicene and 7,12,17-trithia [11] helicene. The optimised geometries of TOH and TTH shows that carbon-carbon bond lengths of inner fused rings vary from terminal rings, as a consequence of generated torsional strain. The IR-spectra displays characteristics peaks in the region of 750-1550 cm -1 in TOH and a slight shift occurs to lower frequency in case of TTH. The vibrational circular dichroism peaks have major contributions from in and out of plane bending and minor contribution from C=C stretching of fused aromatic rings. From ionisation and reorganization energy values it is evident that TOH and TTH can act as hole transport material for OLED device. As a consequence of extended conjugation in studied system, the higher values of polarizability and hyperpolarizability reflects their role in NLO devices.

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“…[1][2][3][4][5] Thus, much affords have been made towards controlling and understanding chirality in chemical synthesis and material design. [10][11][12][13][14][15][16][17] More interesting, the dissymmetric backbone makes helicenes and their derivatives applications in many fields (e.g. [6][7][8][9] Steric hindrance interaction between terminal aromatic rings endows helicenes with helical chirality.…”

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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Synthesis of carbazole derived aza[7]helicenes

Cited by 39 publications

References 54 publications

Synthesis and photophysical properties of bi-aza[5]helicene and bi-aza[6]helicene

Synthesis and photophysical properties of bi-aza[5]helicene and bi-aza[6]helicene

Spectral and optoelectronic studies on 7,12,17-trioxa and 7,12,17-trithia [11] helicenes: a DFT view

Photophysical properties of quinoxaline-fused [7]carbohelicene derivatives

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