Central Cyclopentene Ring Research Articles

Crystal structure and Hirshfeld surface analysis of methyl 4'-amino-3',5'-di-cyano-2,2''-dioxodi-spiro[indoline-3,1'-cyclo-pentane-2',3''-indolin]-3'-ene-5'-carboximidate with an unknown solvent.

In the title compound, C23H16N6O3, the central five-membered cyclo-pentene ring adopts an envelope conformation while the five-membered spiro 2,3-di-hydro-1H-pyrrole rings exhibit twisted envelope and envelope conformations. One of the 1,3-di-hydro-2H-indol-2-one units is in an axial position and the other is in a bis-ectional position. The methyl methanimidate unit is in an equatorial position. The crystal structure of the title compound is consolidated by inter-molecular N-H⋯N, N-H⋯O and C-H⋯O hydrogen bonds, forming a three dimensional network.

Synthesis and the effect of alkyl chain length on photochromic properties of diarylethene derivatives

A new class of photochromic diarylethenes bearing pyrrole and thiophene units with different length of alkyl chains at 2-position of thiophene rings have been synthesized. Their characteristics, including photochromism and fatigue resistance were investigated systematically, and each diarylethene derivative showed good photochromic properties whether in solution or in PMMA films. The alkyl group moiety was connected directly to the central cyclopentene ring as a heteroaryl unit and availably participated in photoisomerization reaction. And some properties, for example, the conversion ratio in the photostationary state(PSS) and the absorption coefficient of the ring-closed isomers in acetonitrile were significantly affected by the alkyl chain length. The results revealed that substituents of alkyl chain played an important role in the photoisomerization process of diarylethenes.

Photochromism of new unsymmetrical diarylethenes with an indazole moiety

A new class of photochromic diarylethenes with an indazole moiety has been firstly synthesized, and their photochromic and fluorescence properties have been investigated. The indazole moiety was connected directly to the central cyclopentene ring as one heteroaryl unit and availably participated in the photoinduced cyclization reaction in solution, amorphous film, as well as in the crystalline phase. These diarylethenes exhibited excellent photochromism with good thermal stability and remarkable fatigue resistance. They also functioned as notable fluorescence switches in both solution and amorphorous films. In addition, the different substituents at the para-position of the terminal benzene ring had a significant effect on their properties: the electron-donating methoxy group could enhance the quantum yields of cyclization and cycloreversion and fluorescence quantum yield, but the electron-withdrawing trifluoromethyl had opposite effect.

ChemInform Abstract: A Novel Strategy for Developing Yellow Diarylethenes Based on Acid Stimulus.

AbstractBuLi‐promoted reaction of the highly fluorinated cyclopentenes (I) with dibromopyridines (II) gives diarylethenes (III) in which the central cyclopentene ring participates in photoisomerization reactions.

Synthesis and photochromism of novel unsymmetrical diarylethenes with an azaindole unit

A new class of unsymmetrical photochromic diarylethenes with an azaindole moiety has been firstly synthesized. Their properties, including photochromism, crystal structure, as well as fluorescence, were investigated systematically. The azaindole was connected directly to the central cyclopentene ring as a heteroaryl moiety and available to participate in the photoisomerization reaction. Each of the diarylethenes exhibited favorable photochromism, good thermal stability, remarkable fatigue resistance, and notable fluorescence switches in both solution and solid media. The substituents at the para-position of the terminal benzene ring affected evidently their properties: the electron-donating methoxy could be effective to enhance the cyclization quantum yield, while the electron-withdrawing cyano could shift the absorption maximum to a longer wavelength in both hexane and solid film. The results revealed that the introduction of azaindole moieties and different substituents played an important role in the photoisomerization process of these diarylethenes.

Photochromism of new unsymmetrical diarylethenes based on the hybrid of azaindole and thiophene moieties

A new class of photochromic diarylethenes with both azaindole and thiophene moieties were synthesized to investigate the effects of the substituents on their photochromic behaviors, and their structures were determined by single crystal X-ray diffraction analysis. The azaindole moiety was connected directly to the central cyclopentene ring as a heteroaryl moiety to participate the photoisomerization reaction in solution, solid amorphous films, and the single crystalline phase. Each of the diarylethenes exhibited remarkable fluorescent photo-switches in both solution and solid media. The electron-donating substituents significantly enhanced their cyclization quantum yields, while the electron-withdrawing groups greatly increased the molar absorption coefficient of their closed-ring isomers. Cyclic voltammetry studies indicated that the band-gaps of diarylethenes with an azaindole notably increased when going from electron-donating substituents to electron-withdrawing substituents. The results revealed that the azaindole moiety and substituents played a vital role in the process of photoisomerization reactions for these diarylethenes.

Photochromism of novel isomeric diarylethenes with benzofuran and pyridine moieties

A new class of isomeric diarylethenes with benzofuran and pyridine moieties was synthesized to investigate the effects of the position of the nitrogen atom in pyridine moiety on their photochromism, acidichromism, and fluorescence. The six-membered pyridine moiety was connected directly to the central cyclopentene ring as an aryl moiety and participated in the photoisomerization reaction in both solution and solid media. These isomeric diarylethenes exhibited multi-addressable switching behavior by the stimulation of acid/base and light. Addition of trifluoroacetic acid to the solutions of these compounds produced the corresponding protonated derivatives. The protonated derivatives exhibited excellent photochromism and notable acidichromism, and the different nitrogen atom position resulted in distinguishable absorption spectra and color changes. The results revealed that the effects of the nitrogen atom position in pyridine moiety played a very important role during the photoisomerization process of these isomeric diarylethenes.

Photochromism of asymmetrical diarylethenes with a pyrimidine unit: Synthesis and substituent effects

Five photochromic diarylethenes with a six-membered pyrimidine moiety were synthesized to investigate the effects of the substituents on their photochromic behaviors, and the structures of four of the diarylethenes were determined by single-crystal X-ray diffraction analysis. The pyrimidine moiety was connected directly to the central cyclopentene ring as an aryl moiety to participate the photoisomerization reaction in solution, solid amorphous films, and crystalline phase. All of the diarylethene derivatives showed favorable photochromism and functioned as notable fluorescent photo-switches in both solution and solid media. The electron-donating substituents enhanced their cyclization quantum yields, fatigue resistance, and fluorescence quantum yields, whereas the electron-withdrawing groups exerted inversed actions on the diarylethenes. The results revealed that the pyrimidine moiety and substituents played a very important role during the process of photoisomerization reactions.

New photochromic 1,2-diarylperfluorocyclopentenes bearing unsymmetrical six-membered aryl units

A new class of unsymmetrical photochromic diarylethenes based on the six-membered naphthalene-benzene and naphthalene-pyridine backbones has been firstly developed and their properties have been discussed. The two different six-membered aryl moieties were connected directly to the central cyclopentene ring and available to participate in the photoinduced cyclization reaction. The three diarylethenes exhibit distinctly different photochromism by photoirradiation in solution: they turn red, yellow, and orange upon photocyclization, which may be resulted from the different substituent and six-membered aryl moiety effects. Compared with the analog bearing a benzene unit, diarylethene bearing a pyridine moiety has a shorter absorption maximum and a smaller fluorescent quantum yield, and it shows a dual-addressable photo-switch by photoirradiation and acid/base stimulation.

New photochromic diarylethenes bearing a condensed aromatics moiety

A new class of diarylethenes based on a hybrid structure of naphthalene and thiophene have been developed and their properties including photochromism, fatigue resistance, and fluorescence have been investigated. The condensed aromatic naphthalene was connected directly to the central cyclopentene ring as an aryl moiety and available to participate in the photoinduced cyclization reaction. All of these compounds have exhibited good photochromism, notable fatigue resistance, and obvious fluorescence photo-switches in both solution and polymer matrix. Nevertheless, significantly different properties have been observed among these diarylethenes, which may be attributed to the effect of different substituent groups. Compared with the analogs bearing other six-membered aryl unit, the naphthalene moiety is more conducive, which leads to higher molar absorption coefficient and blue shift of the absorption maximum.

New photochromic diarylethenes bearing a pyridine moiety

A new class of diarylethenes bearing a pyridine unit has been firstly developed and their properties such as photochromism, fatigue resistance, and fluorescence have been discussed. The pyridine unit was connected directly to the central cyclopentene ring as one aryl moiety and availably participated in the photoinduced cyclization reaction even in the crystalline phase. All of these diarylethenes exhibited excellent photochromism, remarkable fatigue resistance, and notable fluorescence photoswitches both in solution and in poly(methylmethacrylate) films. Moreover, the different substituents had a significant effect on their properties. The results indicated that the electron-donating substituent could significantly enhance the cyclization quantum yield and depress the cycloreversion quantum yield while the electron-withdrawing group had a notable contribution to the cycloreversion quantum yield and fluorescence quantum yield for these diarylethenes.

3-(4-{3,3,4,4,5,5-Hexafluoro-2-[5-(3-methoxyphenyl)-2-methyl-3-thienyl]cyclopent-1-enyl}-5-methyl-2-thienyl)benzonitrile

The title compound, C29H19F6NOS2, is a new unsymmetrical photochromic diarylethene derivative with different meta-phenyl substituents. The distance between the two reactive (i.e. can be irradiated to form a new chemical bond) C atoms is 3.501 (4) Å; the dihedral angles between the mean plane of the main central cyclo­pentene ring and the thio­phene rings are 47.7 (5) and 45.1 (2)°, and those between the thio­phene rings and the adjacent benzene rings are 29.4 (2) and 28.4 (3)°. The three C atoms and the F atoms of hexa­fuorocyclo­pentene ring are disordered over two positions, with site-occupancy factors of 0.751 (4) and 0.249 (4).

2-[2-(N,N-Dimethylamino)phenyl]-3,3,4,4,5,5-hexafluoro-1-(2-methyl-5-phenyl-3-thienyl)cyclopent-1-ene

The title compound, C24H19F6NS, is a new hybrid diaryl­ethene derivative with a 3-thienyl and a six-membered aryl unit as the substituents. In the crystal structure, the F atoms of the central hexa­fluoro­cyclo­pentene ring are disordered, with site occupancies of 0.641 (3) and 0.359 (3). The mol­ecule adopts a photoactive anti­parallel conformation. The distance between the two reactive C atoms, between which a new C—C bond can be formed upon UV irradiation, is 3.504 (5) A. The dihedral angle between the thienyl ring and the adjacent phenyl ring is 12.4 (2)°. The dihedral angle between the central cyclo­pentene ring and the thienyl ring is 46.6 (7)°, and that between the central cyclopentene ring and the dimethyl­aminophenyl ring is 49.7 (4)°.

1,2-Bis[5-(2,4-difluorophenyl)-2-methyl-3-thienyl]-3,3,4,4,5,5-hexafluorocyclopent-1-ene: a new photochromic diarylethene compound

The title compound, C27H14F10S2, is a new symmetrical photochromic diarylethene derivative which can be used potentially for optical recording media and other optoelectronic device materials. There are two independent molecules in the asymmetric unit. Both adopt a photoactive antiparallel conformation. The distances between the reactive C atoms in the two molecules are 3.664 (7) and 3.621 (7) Å. For one molecule, the dihedral angles between the central cyclopentene ring and the thiophene rings are 46.4 (9) and 51.9 (9)°, and those between the thiophene rings and the adjacent benzene rings are 2.1 (8) and 18.9 (8)°. For the other molecule, the dihedral angles between the central cyclopentene ring and the thiophene rings are 134.5 (9) and 44.3 (9)°, and those between the thiophene rings and the adjacent benzene rings are 2.7 (8) and 27.7 (8)°.

2-{4-[2-(2,5-Dimethyl-3-thienyl)-3,3,4,4,5,5-hexafluorocyclopent-1-enyl]-5-methyl-2-thienylmethylene}propanedinitrile: a new photochromic diarylethene compound

The title compound, C20H12F6N2S2, is a new asymmetric photochromic diarylethene which contains 3-thienyl substituents. The distance between the two reactive C atoms in the molecule is 3.677 (8) Å. The dihedral angles between the central cyclopentene ring and the two thiophene rings are 47.6 (2) and 49.2 (2)°.

1-(2,5-Dimethyl-3-thienyl)-3,3,4,4,5,5-hexafluoro-2-(5-formyl-2-methyl-3-thienyl)cyclopent-1-ene: a new photochromic diarylethene compound

The title compound, C17H12F6OS2, is a new nonsymmetric photochromic diarylethene which contains 3-thienyl substituents. The distance between the two reactive C atoms in the molecule is 3.550 (7) Å. The dihedral angles between the central cyclopentene ring and two thiophene rings are 44.7 (3) and 43.6 (3)°.

1,2-Bis[5-(1,3-dioxolan-2-yl)-2-ethyl-3-thienyl]-3,3,4,4,5,5-hexafluorocyclopent-1-ene, a photochromic dithienylethene

The title compound, C23H22F6O4S2, a photochromic dithienylethene, is a promising material for optical storage and other optoelectrical devices. The molecule adopts a photoactive antiparallel conformation in the crystalline state. The distance between the two reactive C atoms which are involved in potential ring closure is 3.829 (4) A. The dihedral angles between the central cyclopentene ring and the adjacent thiophene rings are 55.38 (7) and 54.81 (9) degrees. The colourless crystals turn magenta when exposed to UV radiation and the process is reversible.

An Optical and Theoretical Investigation of the Ultrafast Dynamics of a Bisthienylethene-Based Photochromic Switch

The switching behavior of 1,2-bis(5-phenyl-2-methylthien-3-yl)cyclopentene is studied by means of polarization selective nonlinear optical spectroscopy and time-dependent density functional theory. The combined information from the observed population and orientational dynamics together with the results of theoretical calculations show that on a subpicosecond time scale rapid mixing and relaxation of electronic states occur, before switching takes place. Such preswitching dynamics was not studied in detail in these systems before. Then, the switching process itself occurs by the formation of a C-C bond in the central cyclopentene ring with a time constant of 4.2 ps. Driven by the ring closure, the side groups of the switch molecules rotate to a nearly coplanar conformation with a time constant of about 8 ps. The switching process is completed by relaxation of the vibrationally hot ground state of the closed form of the molecule to thermal equilibrium.

Synthetic approach towards nakadomarin A: efficient synthesis of the central tetracyclic core

An efficient synthesis of the tetracyclic core of nakadomarin A was accomplished starting from methyl 4-oxo-3-piperidinecarboxylate. The key steps were intramolecular cyclization of furan to N-acyliminium ions to construct the strained central cyclopentene ring.

Recent applications of radical reactions in natural product synthesis

Abstract