Fluorescent Bis-Calix[4]arene-Carbazole Conjugates: Synthesis and Inclusion Complexation Studies with Fullerenes C60 and C70

Supramolecular chemistry has become a central theme in chemical and biological sciences over the last decades. Supramolecular structures are being increasingly used in biomedical applications, particularly in devices requiring specific stimuli-responsiveness. Fullerenes, and supramolecular assemblies thereof, have gained great visibility in biomedical sciences and engineering. Sensitive and selective methods are required for the study of their inclusion in complexes in various application fields. With this in mind, two new fluorescent bis-calix[4]arene-carbazole conjugates (4 and 5) have been designed. Herein, their synthesis and ability to behave as specific hosts for fullerenes C₆₀ and C₇₀ is described. The optical properties of the novel compounds and their complexes with C₆₀ and C₇₀ were thoroughly studied by UV-Vis and steady-state and time-resolved fluorescence spectroscopies. The association constants (K_a) for the complexation of C₆₀ and C₇₀ by 4 and 5 were determined by fluorescence techniques. A higher stability was found for the C₇₀@4 supramolecule (K_a = 5.6 × 10⁴ M⁻¹; ΔG = −6.48 kcal/mol). Evidence for the formation of true inclusion complexes between the host 4 and C₆₀/C₇₀ was obtained from NMR spectroscopy performed at low temperatures. The experimental findings were fully corroborated by density functional theory (DFT) models performed on the host–guest assemblies (C₆₀@4 and C₇₀@4).     

Alkyne‐Linked Poly(1,8‐carbazole)s: A Novel Class of Conjugated Carbazole Polymers

Novel conjugated carbazole polymers based on the alkyne‐linked 1,8‐carbazole structure are synthesized in high yield by the Sonogashira cross‐coupling reaction and acetylenic oxidative coupling reaction. The polymers are thermally stable and highly soluble in common organic solvents such as CHCl₃, CH₂Cl₂, and THF. As compared to ethynylene‐linked polymer, the butadiynylene‐linked polymer display a bathochromic shift in the absorption maximum and end absorption position. In addition, the fluorescence behaviors in CH₂Cl₂ are almost identical for both polymers. Electrochemical measurements indicate that the ethynylene‐linked polymer possesses a lower first oxidation potential than the butadiynylene‐linked one.

     

Electroluminescence of a bichromophoric molecule with a benzoxyazolylcoumarin and carbazole moiety

The electroluminescent properties of a bichromophoric molecule in which a benzoxyazolylcoumarin and carbazole moiety is combined with 1,2-ethylene linkage, i.e. 3-(2-benzoxyazolyl)-7-[2-(9-carbazolyl)ethoxy]-coumarin (CmCz), were investigated. CmCz exhibits fluorescence of different colors in a solid state and solution. Two types of device were made. One consisted of a vacuum vapor-deposited film of CmCz as an emission layer to utilize fluorescence in the solid state; the second consisted of a spin-cast film doped with CmCz as an emission material to utilize fluorescence in the solution. The device with a vapor-deposited CmCz film between electrodes shows a green emission with a luminance of less than 10⁻² cd/m². The multiple layer device in which the CmCz film was sandwiched between a hole transport layer and electron transport layer showed a green emission whose spectrum is identical to the photoluminescent spectrum in the vapor-deposited CmCz film. A maximum luminance of the multiple layer device is about 5000 cd/m². On the other hand, the devices consisting of a spin-cast film containing a hole transport material, an electron transport material and CmCz showed a blue emission whose spectra are identical to the photoluminescent spectrum of CmCz in chloroform. Luminance of these devices is over 100 cd/m². © 1997 John Wiley & Sons, Ltd.     

Suppressing charge recombination by incorporating 3,6‐carbazole into poly[9‐(heptadecan‐9‐yl)‐9H‐carbazole‐2,7‐diyl‐alt‐(5,6‐bis‐(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzo[1,2,5]‐thiadiazole)‐5,5‐diyl]

A series of poly[9‐(heptadecan‐9‐yl)‐9H‐carbazole‐2,7‐diyl‐alt‐(5,6‐bis‐(octyloxy)‐4,7‐di(thiophen‐2‐yl)benzo‐[1,2,5]‐thia‐diazole)‐5,5‐diyl] compositions containing various ratios of 3,6‐carbazole was synthesized for testing in a polymer solar cell. An appropriate amount of 3,6‐carbazole units incorporated into the copolymer improved intermolecular charge transport, whereas excess amount of 3,6‐carbazole units temporarily seized on the partial negative charge generated in the conjugation breaks. We extensively studied the effects of the incorporated 3,6‐carbazole units on the intermolecular interactions, which can affect nongeminated recombination in bulk heterojunction‐polymer solar cells. These properties were investigated using photocurrent‐ and light intensity‐dependent measurements and electrochemical impedance spectroscopy. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2047–2056     

Enhancement of redox stability and electrochromic performance of aromatic polyamides by incorporation of (3,6‐dimethoxycarbazol‐9‐yl)‐triphenylamine units

New series aromatic polyamides with (carbazol‐9‐yl)triphenylamine units were synthesized from a newly synthesized diamine monomer, 4,4′‐diamino‐4″‐(3,6‐dimethoxycarbazol‐9‐yl) triphenylamine, and aromatic dicarboxylic acids via the phosphorylation polyamidation technique. These polyamides exhibit good solubility in many organic solvents and can be solution‐cast into flexible and strong films with high thermal stability. They show well‐defined and reversible redox couples during oxidative scanning, with a strong color change from colorless neutral form to yellowish green and blue oxidized forms at applied potentials scanning from 0.0 to 1.3 V. They show enhanced redox‐stability and electrochromic performance as compared to the corresponding analogs without methoxy substituents on the active sites of the carbazole unit. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 272–286     

Covalent Modification of Graphene Oxide with Carbazole Groups for Laser Protection

In the past decades, significant effort has been invested into the research and development of optical limiting materials and processes in order to develop practical solutions for the protection from laser beams. In this study, a new soluble graphene oxide based material (GO–Cz) has been synthesized through the covalent modification of graphene oxide (GO) with a carbazole derivative (Cz). The formation of an amido bond between the Cz group and GO has been confirmed by X‐ray photoelectron and Fourier transform infrared spectroscopy. At the same concentration, both the nonlinear extinction coefficient and the imaginary third‐order susceptibility were increased by a factor of ≈6.93 at 532 nm and ≈6.07 at 1064 nm relative to those of GO, as a result of the covalent grafting of the Cz moieties onto the GO surface. The GO–Cz dispersions exhibit a much better optical limiting performance than GO and GO/Cz blends at both 532 and 1064 nm due to the possible intramolecular electron‐transfer between the GO and Cz moieties and the effective combination of the different nonlinear optical mechanisms.     

Amphiphilic copolymers with pendant ­carbazolylalkyl groups. ­Effect of polymer structure on ­retardation of self‐quenching

A series of amphiphilic polyanions containing (9‐carbazolyl)alkyl methacrylamide or acrylamide were prepared and their fluorescence properties were compared in organic and aqueous solution. In organic solution, all copolymers exhibited a monomer emission which decayed exponentially, indicating no self‐quenching. Decreasing the length of the methylene spacer in the side chain induced the spectral broadening and sharpening, depending on the carbazolyl content in the copolymer. This may be related to the interchromophore interactions and the mobility of chromophores. In H ₂O, by contrast, quenched fluorescence was observed for the copolymers. It should be however noted that acrylamide‐type of amphiphilic copolymers, poly(9‐carbazolylmethyl‐acrylamide‐co‐sodium 2‐acrylamido‐2‐methylpropanesulfonate), are the least quenched polymers among those reported so far. Copyright © 2001 John Wiley & Sons, Ltd.     

Photoinduced intramolecular electron transfer of fluorescein and violgen, carbazole

A series of polyads consisting of covalently-(CH2)4-linked fluorescein with carbazole and violger.Live been synthesized and characterized The studies of absorption,emission spectra and fluorescence lifetime quenching indicated that the intramolecular fluorescence quenching of fluorescein by violgen is mainly a static process through the formation of non emission complex (fluorescence quenching efficiency φQ=0.97,lifetime quenching efficiency φH 0,quenching efficiency of formation of non-emission complex φC=0.97); while the quenching by carbazole is mainly a dynamic electron transfer process (φQ=0.63,φET=0.63,φC=0).In the violgen-fluorescein-carbazole triads,φQ=0.97,Q ET=0.65,φC=0.32,which suggests that the photoinduced interaction of fluorescein-carbazole pair and that of violgen-fluorescein pair are in a competitive process,the dynamic electron transfer from carbazole to fluorecein is dominant in the process The free energy change of the photoinduced electron transfer and the back reac-tiorns i     

Investigation of 3-(carbazol-9-YL)-1,2-epithiopropane interaction with aromatic amines

In the reaction of 9-(2,3-epithiopropyl)-9H-carbazole with aromatic amines (aniline, 4-methoxy-, 4-methyl-, 4-fluoro-, 4-bromo-, 4-chloro-, 3-chloro-, 2-chloroaniline) and subsequent oxidation of the mixtures formed of propanethiols and disulfides with 25% H₂O₂ in basic solutions the respective disulfides have been synthesized. Carbazolyl-containing derivatives of the thiazolidine have been obtained.Published in Khimiya Geterotsiklicheskikh Soedinenii. No. 1, pp. 90–99, January, 2000.     

双（N—苯基—3—咔唑基）甲苯碘盐的合成

双（Ｎ┐苯基┐３┐咔唑基）甲苯碘盐的合成李笃信＊郭自强兰卫东（山西大学化学系太原０３０００６）关键词苯基咔唑甲苯碘盐，有机光电导体，敏化剂，合成１９９７－１０－２７收稿，１９９８－０３－１３修回山西省自然科学基金资助项目有机光电导体简称ＯＰＣ，因其具...