Synthesis, structure and properties of various molecules based on the 4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene system with an evaluation of the effect differing molecular substitution patterns has on the space group symmetry

Faldt, André; Krebs, Frederik C.; Thorup, Niels

doi:10.1039/a703641h

Cited by 30 publications

(34 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[11] As a consequence, phenalenyl derivatives exhibit unique physical properties and functionalities different from the those of spin-localized neutral radicals such as nitroxide derivatives. The five-step synthesis from 1tert-butyl-3,5-dimethoxybenzene (2) [16] is depicted in Scheme 1. [13,14] Cor-PLY is the first nonplanar phenalenyl derivative in the half-century-old phenalenyl chemistry.…”

mentioning

confidence: 99%

Chiral Stable Phenalenyl Radical: Synthesis, Electronic‐Spin Structure, and Optical Properties of [4]Helicene‐Structured Diazaphenalenyl

et al. 2012

View full text Add to dashboard Cite

Helicenes are ortho-annelated polycyclic aromatic molecules with nonplanar helical conjugation of the p-electron system. [1] These aromatic molecules have attracted special attention not only because of the nonplanarity of the p-conjugated skeleton but also because of their inherent helical chirality. Recent developments in helicene chemistry have focused on the synthesis and optical resolution of new helicene derivatives [2] as well as on asymmetric catalysts, [3] molecular recognition, [4] and chiroptical functionalities. [5,6] However, almost all of the helicene derivatives investigated so far are intrinsically closed-shell electronic systems except for a few examples. [7] Thus, the chemistry of open-shell helicenes has been little explored in the past; to our knowledge there have been no experimental studies on helicene-based nonplanar chiral neutral p-radical systems. [8] As stable open-shell molecular systems possessing chirality, a number of nitroxide-based chiral neutral radical derivatives have been synthesized and characterized. [9] These systems were constructed by introducing a substituent having one or more asymmetric carbon atoms to an achiral nitroxide radical skeleton based on, for example, pyrrolidine-1-oxyl and a-nitronylnitroxide. By taking advantage of the localized unpaired electronic spin on the NÀO moiety, chiral molecular magnets and paramagnetic organic chiral liquid crystals have extensively been implemented. [9b, 10] In contrast to the nitroxide radicals, in phenalenyl (PLY in Figure 1), a planar neutral hydrocarbon p-radical, the electronic spin is extensively delocalized over the whole molec-ular skeleton. [11] As a consequence, phenalenyl derivatives exhibit unique physical properties and functionalities different from the those of spin-localized neutral radicals such as nitroxide derivatives. [11,12] Furthermore, our recent study revealed that the highly delocalized electronic structure inherent in phenalenyl also appears in a curved phenalenyl system with a corannulene substructure (Cor-PLY, Figure 1). [13,14] Cor-PLY is the first nonplanar phenalenyl derivative in the half-century-old phenalenyl chemistry.These studies have inspired us to design nonplanar pconjugated chiral phenalenyl radicals based on helicene. [11b] The chiral neutral p-radical is intriguing not only because of the spin delocalization in the three-dimensional (3D) helical p-conjugated network but also because of optical magnetic properties attributable to the combination of helicene chirality and delocalized electronic spin. Here we report the synthesis, electronic-spin structure, and optical properties of chiral diazaphenalenyl 1 (Figure 1), [15] in which a benzene ring is fused to a nitrogen-containing [4]helicene-type structure. Thanks to two terminal methoxy groups and three tert-butyl groups, radical 1 exhibits high configurational and chemical stability, enabling us to experimentally characterize both chiral and racemic species of 1 with the help of theoretical calculations. Solution-phase ESR and EN...

show abstract

mentioning

confidence: 99%

Chiral Stable Phenalenyl Radical: Synthesis, Electronic‐Spin Structure, and Optical Properties of [4]Helicene‐Structured Diazaphenalenyl

et al. 2012

View full text Add to dashboard Cite

show abstract

“…In the course of our efforts to develop malaria mosquito-selective acetylcholinesterase inhibitors, 1 we required such compounds, which we term “Friedel-Crafts-restricted” tert -alkyl benzenes. Traditional strategies to prepare these compounds use “temporary” ortho - or para -hydroxy or amino groups to direct Friedel-Crafts 2 or other electrophilic aromatic substitution reactions; 3,4 subsequent removal of the temporary directing group then unveils the desired meta -substitution pattern. We sought a more direct route that would benefit from the large number of commercially available meta -substituted benzoic acids and acetophenones.…”

Section: Introductionmentioning

confidence: 99%

Access to “Friedel–Crafts-Restricted” tert-Alkyl Aromatics by Activation/Methylation of Tertiary Benzylic Alcohols

et al. 2012

View full text Add to dashboard Cite

Herein we describe a two-step protocol to prepare m-tert-alkylbenzenes. The appropriate 3° benzylic alcohols are activated with SOCl2 or concentrated HCl, and then treated with trimethylaluminum, affording the desired products in 68–97% yields (22 examples). This reaction sequence is successful in the presence of a variety of functional groups, including acid-sensitive and Lewis-basic groups. In addition to t-Bu groups, 1,1-dimethylpropyl and 1-ethyl-1-methylpropyl groups can also be installed using this method.

show abstract

“…[16] Therefore the design of new molecular pyroelectric materials continues to involve synthesizing a series of candidates, solving their crystal structures and, if potentially promising, measuring the pyroelectric coefficient of sometimes minute single crystals. [17] The main advantage of extracting pyroelectric coefficients with the method described here is that it can be applied to any crystal suitable for X-ray diffraction. This means that smaller crystals than usual can be screened, thereby facilitating the synthetic procedure.…”

mentioning

confidence: 99%

Evaluation of the Solid State Dipole Moment and Pyroelectric Coefficient of Phosphangulene by Multipolar Modeling of X-ray Structure Factors

et al. 2000

Self Cite

View full text Add to dashboard Cite

The electron density distribution of the molecular pyroelectric material phosphangulene has been studied by multipolar modeling of X-ray diffraction data. The "in-crystal" molecular dipole moment has been evaluated to 4.7 D corresponding to a 42% dipole moment enhancement compared with the dipole moment measured in a chloroform solution. It is substantiated that the estimated standard deviation of the dipole moment is about 0.8 D. The standard uncertainty (s.u.) of the derived dipole moment has been derived by splitting the dataset into three independent data-sets. A novel method for obtaining pyroelectric coefficients has been introduced by combining the derived dipole moment with temperature-dependent measurements of the unit cell volume. The derived pyroelectric coefficient of 3.8(7) x 10-6 Cm 2K-1 is in very good agreement with the measured pyroelectric coefficient of p = 3 +/- 1 x 10-6 Cm-2 K-1. This method for obtaining the pyroelectric coefficient uses information from the X-ray diffraction experiment alone and can be applied to much smaller crystals than traditional methods.

show abstract

Synthesis, structure and properties of various molecules based on the 4,8,12-trioxa-4,8,12,12c-tetrahydrodibenzo[cd,mn]pyrene system with an evaluation of the effect differing molecular substitution patterns has on the space group symmetry

Cited by 30 publications

References 10 publications

Chiral Stable Phenalenyl Radical: Synthesis, Electronic‐Spin Structure, and Optical Properties of [4]Helicene‐Structured Diazaphenalenyl

Chiral Stable Phenalenyl Radical: Synthesis, Electronic‐Spin Structure, and Optical Properties of [4]Helicene‐Structured Diazaphenalenyl

Access to “Friedel–Crafts-Restricted” tert-Alkyl Aromatics by Activation/Methylation of Tertiary Benzylic Alcohols

Evaluation of the Solid State Dipole Moment and Pyroelectric Coefficient of Phosphangulene by Multipolar Modeling of X-ray Structure Factors

Contact Info

Product

Resources

About