Remarkable Effects of Terminal Groups and Solvents on Helical Folding of <i>o</i>-Phenylene Oligomers

Ando, Shinji; Ohta, Eisuke; Kosaka, Atsuko; Hashizume, Daisuke; Koshino, Hiroyuki; Fukushima, Takanori; Aida, Takuzo

doi:10.1021/ja303117z

Cited by 64 publications

(106 citation statements)

References 32 publications

Supporting

Mentioning

100

Contrasting

Order By: Relevance

“…Supporting Information (see footnote on the first page of this article): Experimental details, characterization data, and copies of the 1 H NMR and 13 C NMR spectra of all key intermediates and final products.…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Structure of N‐Hetero‐ortho‐phenylene Hexamers Containing 2,3‐Substituted Pyridine Moieties

et al. 2015

View full text Add to dashboard Cite

N‐Hetero‐ortho‐phenylene hexamers with two 2,3‐substituted pyridine moieties (i.e., 1a–c) were prepared by palladium‐catalyzed homocoupling with pyridine‐directed C–H cleavage as the key step. The conformations of the resulting hexamers in solution and in the solid state were investigated by computational methods, X‐ray analysis, and 1H NMR spectroscopy. Calculations at the SCS‐MP2/def2‐TZVPP//B97‐D3(bj)/def2‐SVP level suggested that helical folding of 1a as the pyridine moieties are stacked is thermally more stable than the equivalent folding in the unsubstituted ortho‐phenylene hexamer. The conformations of single crystals of 1 were consistent with the optimized structures obtained by DFT calculations. Except for rotation of the terminal phenyl groups, only one set of signals corresponding to a helical conformation was observed by analysis of 1 by 1H NMR spectroscopy in CDCl3 solution.

show abstract

Section: Discussionmentioning

confidence: 99%

Synthesis and Structure of N‐Hetero‐ortho‐phenylene Hexamers Containing 2,3‐Substituted Pyridine Moieties

et al. 2015

View full text Add to dashboard Cite

show abstract

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Due to their heavily angled aromatic connection, oligomeric o-phenylenes are able to adopt a closely packed helical conformation featuring axial chirality. Oligomeric and polymeric o-phenylenes, consisting of multiple phenylene units linked together at their ortho-positions, are an emerging class of such helical molecules.…”

Section: Introductionmentioning

confidence: 99%

Scanning tunnelling microscopy analysis of octameric o-phenylenes on Au(111)

et al. 2016

Self Cite

View full text Add to dashboard Cite

Oligomeric o-phenylenes are an emerging class of helical molecules that exhibit complex conformational behaviour, which is determined by their terminal groups and the solvent environment. Using scanning tunnelling microscopy (STM), we investigated the conformational behaviour of octameric o-phenylenes (OP 8 s) featuring Br or NO 2 terminal groups (OP 8 Br and OP 8 NO 2 ). These o-phenylene oligomers are known to adopt a well-defined helical conformation in the solid state, but undergo a rapid helical inversion in solution at ambient temperature. We show that STM microscopy allows the direct observation of perfectly and partially folded helical conformers of OP 8 Br and OP 8 NO 2 , both of which are simultaneously present in their respective molecular films on Au(111). Possible electronic interactions between the Au(111) surface and the exposed p-system of the OP 8 derivatives might result in a thermodynamic bias able to stabilize the metastable, partially folded conformation. Recent studies have revealed that the helical inversion rate of OP 8 NO 2 in solution decreases substantially upon oxidation to the corresponding radical cation (OP 8 NO 2 c + ). The OP 8 NO 2 and OP 8 NO 2 c + film morphologies on Au (111) observed by STM differed substantially with respect to each other, most likely reflecting differences arising from the conformational states of OP 8 NO 2 and OP 8 NO 2 c + at the molecular level, as well as improved charge-transport properties of the oxidized state. † Electronic supplementary information (ESI) available: STM images of a clean Au substrate and OP 8 Br and OP 8 NO 2 lms on Au(111), analytical data for an STM image of an OP 8 Br lm on Au(111), as well as Cartesian coordinates and energies of the theoretically optimized structures of the perfectly and partially folded conformers. See

show abstract

“…Connections of aromatics through non-a or non-para positions for five-and six-membered rings, respectively, impart unique topologies onto the secondary structures of p-conjugated wires through heavily angled aromatic connections. [1][2][3][4][5][6][7][8] The conformational behaviors of o-phenylenes, in particular, have been extensively studied in regard to their dynamic nature, redox response, and effect of substituents and end-groups. [2][3][4][5] However, there are only a few examples of o-arylene analogues composed of more compact five-membered heteroaromatics despite their versatility in p-conjugated molecular wires with excellent electric and optical properties.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8] The conformational behaviors of o-phenylenes, in particular, have been extensively studied in regard to their dynamic nature, redox response, and effect of substituents and end-groups. [2][3][4][5] However, there are only a few examples of o-arylene analogues composed of more compact five-membered heteroaromatics despite their versatility in p-conjugated molecular wires with excellent electric and optical properties. [6][7][8] Recently, Fallon et al reported the synthesis of b-oligofurans and their conformational preferences.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structure, and Properties of α,β‐Linked Oligothiazoles with Controlled Sequence

Nakashima

Imamura

Yamamoto

et al. 2014

Chemistry A European J

View full text Add to dashboard Cite

α,β-Linked oligothiazoles with head-to-tail connectivity are presented as a new family of helical scaffolds. Combinations of palladium-catalyzed cross-coupling reactions at the 5- and 4-positions of 2-phenylthiazole led to the synthesis of oligo(2-phenylthiazoles) with ortho linkages with a variety of defined sequences. The secondary structures of the α,β-linked oligo(2-phenylthiazoles) showed a clear dependence on their sequences. X-ray crystallography of the trimer, tetramer, and hexamer with head-to-tail connection revealed the formation of a helical structure, which was stabilized by a combination of intramolecular forces, including interheteroatom (S⋅⋅⋅N), CH-π, and π-π interactions. The introduction of a chiral end-group successfully led to the induction of chirality into the helical conformations. Programmable sequences for controlled geometries and photofunctions have been demonstrated through the manifold connection pathways in α,β-linked oligothiazoles.

show abstract

Remarkable Effects of Terminal Groups and Solvents on Helical Folding of o-Phenylene Oligomers

Cited by 64 publications

References 32 publications

Synthesis and Structure of N‐Hetero‐ortho‐phenylene Hexamers Containing 2,3‐Substituted Pyridine Moieties

Synthesis and Structure of N‐Hetero‐ortho‐phenylene Hexamers Containing 2,3‐Substituted Pyridine Moieties

Scanning tunnelling microscopy analysis of octameric o-phenylenes on Au(111)

Synthesis, Structure, and Properties of α,β‐Linked Oligothiazoles with Controlled Sequence

Contact Info

Product

Resources

About