- Dual Emission of meso-Phenyleneethynylene–BODIPY Oligomers: Synthesis, Photophysics, and Theoretical Optoelectronic Study
-
Two series of 2,5-di(butoxy)phenyleneethynylenes, one halogenated (nPEC4-X; n=2, 3, or 4) and the other boron-dipyrromethene (BODIPY) terminated (nPEC4-By; n=3, 4, or 5; By=BODIPY), were synthesized monodirectionally by the step-by-step approach and the molecular structure was corroborated by NMR spectroscopy (1H, 13C-DEPTQ-135, COSY, HSQC, HMBC, 11B, 19F) and MALDI-TOF mass spectrometry. The multiplicity and J-coupling constants of 1H, 11B, and 19F/11B NMR signals revealed, in the nPEC4-By series, that the phenyl in the meso position of BODIPY becomes electronically part of the conjugation of the phenyleneethynylene chain, whereas BODIPY is electronically isolated. The photophysical, electrochemical, and theoretical studies confirm this finding because the properties of nPEC4-By are comparable to those of the nPEC4-X oligomers and BODIPY, indicating negligible electron communication between BODIPY and the nPEC4 moieties. Nevertheless, energy transfer (ET) from nPEC4 to BODIPY was rationalized by spectroscopy and theoretical calculations. Its yield decreases with the nPEC4 conjugation length, according to the increase in distance between the two chromophores, resulting in dual emission for the longest oligomer in which ET is quenched.
- Flores, J. Reyes,Castruita-De León, Griselda,Turlakov, Gleb,Arias, Eduardo,Moggio, Ivana,Montemayor, Sagrario M.,Torres, Román,Ledezma, Raquel,Ziolo, Ronald F.,González-Torres, Julio
-
p. 2493 - 2505
(2020/12/23)
-
- Synthesis, mesomorphic properties and nonlinear optical studies of alkyl and alkoxy phenylacetylene containing phenazine fused extended triphenylene discotic liquid crystalline dyes
-
Herein, we have reported the alkyl and alkoxy phenylacetylene containing phenazine fused triphenylene discotic liquid crystals (DLCs) which are obtained by the condensation reaction of triphenylene-1,2-diquinone with 1,2-diamino-4,5-dibromobenzene, followed by Sonogashira C–C coupling reaction with 4-alkyl-phenylacetylene or 4-alkoxy-phenylacetylene. Six novel derivatives were synthesized and evaluated for their thermal and optical properties. They show a broad range of hexagonal columnar phase and retain their mesophase up to room temperature upon cooling from the isotropic liquid. Thermotropic liquid crystalline properties of all the compounds were studied by polarised optical microscopy (POM), differential scanning calorimetry (DSC). The self-assembly of mesophase structure was investigated by X-ray diffraction (XRD) studies. Thermogravimetric analysis of all the mesogens shows good thermal stability over a broad temperature range. The photophysical properties of newly synthesized compounds were measured using UV–Vis absorption and photoluminescence emission spectroscopy in anhydrous chloroform solvent. The π-extended conjugation in these mesogens exhibit strong absorption bands falling around 270–487 nm and corresponding emission band at 657–663 nm respectively. The high delocalization of π– electrons in extended discotic mesogens show high nonlinear optical properties when measured under excitation by nanosecond laser pulses at 532 nm. These materials may find distinctive applications in the semiconducting devices.
- Gowda, Ashwathanarayana,Jacob, Litwin,Patra, Alakananda,George, Agnes,Philip, Reji,Kumar, Sandeep
-
p. 128 - 135
(2018/08/07)
-
- Alkyloxy modified pyrene fluorophores with tunable photophysical and crystalline properties
-
Novel alkyloxy modified 2,7-di-tert-butyl-4,5,9,10-tetra(arylethynyl)pyrenes were prepared through a straightforward Sonogashira coupling approach. Optical properties such as quantum yields and absorption/emission spectra of the fluorophores were investigated by UV/Vis and fluorescence measurements. Aggregation induced excimer formation of the chromophores in polar solvents and in the solid state was proved by the presence of a characteristic bathochromically shifted emission band and a decrease of the emission capability. These results strongly indicate the unexpected observation that the excimer formation of adjacent pyrene rings is not prevented by the introduction of bulky tert-butyl substituents. Single-crystal X-ray and computational analyses reveal the co-planar alignment of adjacent molecules and the presence of π-π-stacking in the molecular packing of the pyrene polyaromatics. Furthermore, fluorescence, DSC and POM measurements indicate that the aggregation behaviour, the thermal characteristics and the crystalline properties are significantly influenced by changing structural features of the attached functional groups at the periphery of the pyrene core.
- Kapf, Andreas,Eslahi, Hassan,Blanke, Meik,Saccone, Marco,Giese, Michael,Albrecht, Marcel
-
p. 6361 - 6371
(2019/04/25)
-
- Reactivity switch enabled by counterion: Highly chemoselective dimerization and hydration of terminal alkynes
-
A counterion-controlled reactivity tuning in Pd-catalyzed highly chemoselective and regioselective dimerization and hydration of terminal alkynes is reported. The use of acetate as counterion favors the formation of an alkenyl alkynyl palladium intermediate which forms hitherto less reported 1,3-diaryl-substituted conjugated enynes after reductive elimination. Using chloride, which is a better leaving group, leads to anion exchange on the alkenylpalladium intermediate with hydroxide which after reductive elimination and tautomerization delivered the hydration products.
- Xu, Caixia,Du, Weiyuan,Zeng, Yi,Dai, Bin,Guo, Hao
-
p. 948 - 951
(2014/03/21)
-
- Synthesis of diphenyl-diacetylene-based nematic liquid crystals and their high birefringence properties
-
We synthesized two series of diphenyl-diacetylene (DPDA)-based materials with alkoxy and alkyl tails of length m (DPDA-OCm and DPDA-Cm, respectively), and measured their nematic-phase birefringence (Δn) as a function of wavelength and temperature. We found that Δn decreases with an increase in m, possibly by a dilution effect of the low-Δn alkyl tail. Further, of the two series, Δn was found to be relatively higher in the DPDA-OCm materials, with the highest value of 0.4 obtained for DPDA-OC1 at 550 nm at 10 °C below the isotropic-to-nematic transition temperature. Further, we observed the temperature dependence for Δn, which is proportional to the order parameter (s). From extrapolation to s = 1 (the perfect orientation state), it is speculated that the DPDA-O moiety has the potential to afford a very large Δn of 0.9. The Royal Society of Chemistry 2012.
- Arakawa, Yuki,Nakajima, Shunpei,Ishige, Ryohei,Uchimura, Makoto,Kang, Sungmin,Konishi, Gen-Ichi,Watanabe, Junji
-
p. 8394 - 8398
(2012/07/28)
-
- High birefringence nematic liquid crystals for display and telecom applications
-
Several compounds with high birefringence and, having tolane structure were synthesized. For a high polarizability, isothiocyanato (NCS) terminal group was introduced. Another goal of this study was reduction of melting point and smectic phases by introduction of fluorine as lateral substituent. The transition temperatures for all the synthesized compounds and the refractive and dielectric indices for one of the compounds have been determined. Electro-optic (EO) measurements were also performed.
- Catanescu, Carmen Otilia,Chien,Wu, Shin-Tson
-
p. 93/[1135]-102/[1144]
(2007/10/03)
-
- Synthesis and mesomorphic properties of some fluorinated benzoate liquid crystals
-
Three series of [4-(4′-n-alkyloxyphenyl)acetylenyl]-2,6- difluorophenyl fluorinated benezoates and one series of fluorinated benzoates with 2,3,5,6-tetrafluorophenylene group and semi-perfluorocarbon chain have been synthesized. Their phase transition temperatures have been measured by texture observation in a polarizing microscope and confirmed by DSC. For the series without fluorocarbon chains, increasing the quantity of fluorosubstituents on the terminal phenyl groups decreased nematic stability (TN-I), but the breadth of the SmA phase range was increased. Lateral fluorosubstitution in the central group lowered the nematic stability (TN-I) and decreased the breadth of the SmA phase range. The series with semiperfluorocarbon chains were more likely to form SmA phases than the series with hydrogencarbon chains, and with the increasing of fluorosubstituents quantity on the terminal phenyl groups nematic and SmA stability (TN-I and TsmA-N) were both decreased.
- Yang, Yong Gang,Chen,Tang,Wen
-
-
- Synthesis and mesomorphic properties of some fluoro-substituted benzoates
-
Several series of fluoro-substituted benzoate liquid crystals have been synthesized. The results showed that the SmA phase is enhanced with the increasing of the degree of fluoro-substitution on the para- and meta-position of the terminal phenyl groups. And the molecules which have same molecular structural formula show nearly the same melting points. It is also discussed about the effect of the ester bond's direction on the mesomorphic properties.
- Yang,Tang,Gong,Wen
-
p. 153 - 165
(2007/10/03)
-
- Synthesis, transition temperatures, and optical properties of compounds with simple phenyl units linked by double bond, triple bond, ester or propiolate linkages
-
A series of compounds has been prepared with 4-butylsulfanylphenyl and 4-cyano- or 4-isothiocyanato-phenyl units connected by -CH=CH-, -COO-, -C≡C- , or -C≡C-COO- linking groups. The synthesis of the novel compounds is presented and the transition temperatures and optical parameters of the compounds are discussed and compared with those for related biphenyl reference systems. The ester linking group reduces optical and polarisability anisotropy, but the other linking groups give increased optical anisotropy (up to Δn = 0.50) and polarisability anisotropy [up to Δα = 45.2 A3 (10-30 m3)].
- Cross, Gregory J.,Seed, Alexander J.,Toyne, Kenneth J.,Goodby, John W.,Hird, Michael,Artal, M. Carmen
-
p. 1555 - 1563
(2007/10/03)
-