Novel fluorophores: efficient synthesis and photophysical properties

The synthesis of new donor-acceptor acetylene-bridged compounds was realized via organophosphorus reactions and Sonogashira couplings. These systems exhibit high fluorescence quantum yields, and excitation induces very efficient charge redistribution in the molecules. [structure: see text]     

Facile synthesis and photophysical properties of 1,2-phenylene-bridged porphyrin dimers

Facile synthesis of 1,2-phenylene-bridged porphyrin dimers via Pd-catalyzed cross-coupling reaction and their photophysical properties only moderately perturbed by inter-porphyrin electronic interactions are reported.     

Fluorine-containing quinoline and quinoxaline styryl derivatives: synthesis and photophysical properties

(E)-2-Styryl-substituted 6,7-difluoroquinolines and quinoxalines were synthesized by the condensation of the corresponding 2-methylbenzazines with aromatic aldehydes. Photoluminescence of the synthesized 6,7-difluoro-2-styrylbenzazines was studied.     

Asymmetrically tetra-substituted phthalocyanine derivatives: synthesis,photophysical and photochemical properties

Transition Metal Chemistry - The syntheses of highly soluble asymmetrically substituted metal free and zinc phthalocyanine derivatives bearing three 4-(4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenoxy) and...     

Novel 8-arylidenetetrahydroquinazoline N-oxides: synthesis,photophysical properties and biological evaluation

1. Download : Download high-res image (107KB)
2. Download : Download full-size image

     

Glaser-mediated synthesis and photophysical characterization of diphenylbutadiyne-linked porphyrin dyads

The Pd-mediated Glaser coupling of a zinc monoethynyl porphyrin and a magnesium monoethynyl porphyrin affords a mixture of three 4,4'-diphenylbutadiyne-linked dyads comprised of two zinc porphyrins (Zn-pbp-Zn), two magnesium porphyrins (Mg-pbp-Mg), and one metalloporphyrin of each type (Zn-pbp-Mg). The latter is easily isolated due to the greater polarity of the magnesium versus the zinc chelate. Exposure of Zn-pbp-Mg to silica gel results in selective demetalation, affording Zn-pbp-Fb where Fb = free base porphyrin. This synthesis route employs the magnesium porphyrin as a latent form of the Fb porphyrin, thereby avoiding copper insertion during the Glaser reaction, and as a polar entity facilitating separation. The absorption spectrum of Zn-pbp-Mg or Zn-pbp-Fb is the sum of the spectra of the component parts, while in each case the fluorescence spectrum upon illumination of the Zn porphyrin is dominated by emission from the Mg or Fb porphyrin. Time-resolved absorption spectroscopy shows that the energy-transfer rate constants are (11 ps)(-1) and (37 ps)(-1) for Zn-pbp-Mg and Zn-pbp-Fb, respectively, corresponding to energy-transfer quantum yields of 0.995 and 0.983, respectively. The calculated F?rster through-space rates are (1900 ps)(-1) and (1100 ps)(-1) for Zn-pbp-Mg and Zn-pbp-Fb, respectively. Accordingly, the through-bond process dominates for both dyads with a through-bond:through-space energy-transfer ratio of > or =97:1. Collectively, the studies show that the 4,4'-diphenylbutadiynyl linker supports fast and efficient energy transfer between Zn and Mg or Fb porphyrins.     

Novel fluorophores: efficient synthesis and photophysical study

[structure: see text] We have synthesized novel fluorophores by using Sonogashira reactions of 1,4-bis(dibromovinyl)benzene and 2,5-bis(dibromovinyl)thiophene with various aromatic bromides. The emission maxima of these fluorophores vary from the indigo blue to the reddish-orange region, depending on the structures of aromatic nuclei and peripheral moieties.     

New synthesis of pyrazole and isoxazole derivatives

A convenient synthesis of 5-aryl-1-phenylpyrazoles and 5-arylisoxazoles, from readily available ketimine 1 dimethylformamide dimethylacetal and phenylhydrazine or hydroxylamine, is described.     

Heteroaromatic alanine derivatives bearing (oligo)thiophene units: synthesis and photophysical properties

A series of new benzoxazolylalanine derivatives bearing (oligo)thiophene units at the side chain were synthesized in good yields. The photophysical characterization of these amino acids was performed by UV-vis absorption and fluorescence emission studies and revealed that some of the compounds display high fluorescent quantum yields, making them good candidates for application as fluorescent probes.     

Novel silicon-based alternating copolymers: synthesis,photophysical properties,and tunable EL colors

We synthesized novel silicon-based alternating copolymers for tunable electroluminescent (EL) colors by Heck synthetic method. Their thermal, photophysical and electroluminescent properties were studied. Most of them exhibited a blue-green EL color at the operating voltage of lower than 12 V. Unusually, we observed the white EL color from a EL device based on SiPhPVK. From photophysical studies and the time-resolved PL spectroscopies, it might be attributed to the formation of stabilized excited state in SiPhPVK. Furthermore, in order to reduce the operating voltage of their LED with increasing the electron affinity of the main chain in silicon-based alternating copolymers, we synthesized the silicon-based copolymers containing electron transporting oxadiazole units in main chain. We also studied their photophysical and electroluminescent properties.     

Novel derivatives of UDP-glucose: concise synthesis and fluorescent properties

A series of novel 5-substituted UDP-glucose derivatives with interesting fluorescent properties and potential applications as sensors for carbohydrate-active enzymes is reported. An efficient synthesis of the target molecules was developed, centred around the Suzuki-Miyaura reaction of (hetero)arylboronic acids with 5-iodo UDP-glucose. Interestingly, the optimised cross-coupling conditions could also be applied successfully to 5-bromo UMP, but not to 5-bromo UDP-glucose.     

The synthesis,X-ray crystal structure and optical properties of novel 1,3,5-triaryl pyrazoline derivatives

A series of novel 1,3,5-triaryl pyrazoline derivatives has been synthesized by the reaction of chalcone and 3-chloro-6-hydrazinylpyridazine in 47–82% yields. The structures of compounds obtained were determined by IR, ¹H NMR and HRMS spectra. Representatively, the spatial structure of compound 3d was determined by using X-ray diffraction analysis. Absorption and fluorescence spectral characteristics of the compounds were investigated in CHCl₃ by UV–vis absorption and emission spectra. The results showed that the absorption maxima of the compounds vary from 332 to 342 nm depending on the group bonded to benzene rings. The maximum emission spectra of compounds in CHCl₃ are dependent on groups in benzene ring in which a strong electron-donating group in benzene ring such as methoxyl group on C3 position of pyrazoline made the emission wavelength of 3e, 3f and 3g red shifted than that of compounds 3b, 3c and 3d with chlorine group. The intensity of absorption and fluorescence was also correlated with substituent on two aryl rings. In addition, the absorption spectra of these compounds change very little with increasing solvent polarity.     

Fluorenyl dendrimer porphyrins: synthesis and photophysical properties

New symmetrical dendrimeric type super-porphyrin bearing sixteen fluorenyl donor groups sixteen fluorenylporphyrin SOFP (1) have been synthesized and characterized. Preliminary photophysical properties are reported; in comparison to the references first generation dendrimer tetrafluorenylporphyrin TOFP (2) bearing four peripheral fluorenyl and second generation dendrimer octafluorenylporphyrin OOFP (3) bearing eight peripheral fluorenyl, the luminescence properties are slightly improved. It is found that the excitation energy transfer occurs from the sixteen fluorenyl units to the porphyrin core, following what the porphyrin emits intense red light.     

Optical and photophysical properties of indolocarbazole derivatives

We present a study of the optical and photophysical properties of five ladder indolo[3,2-b]carbazoles, namely, M1, M2, M3, M4, and M5. The ground-state optimized structures were obtained by B3LYP/6-31G* density functional theory (DFT) calculations, whereas the optimization (relaxation) of the first singlet excited electronic state (S1) was performed using the restricted configuration interaction (singles) (RCIS/6-31G*) approach. The excitation to the S1 state does not cause important changes in the geometrical parameters of the compounds, as corroborated by the small Stokes shifts. The excitation and emission energies have been obtained by employing the time-dependent density functional theory (TDDFT). For all the compounds, excitation to the S1 state is weakly allowed, whereas the S2 <-- S0 electronic transition of each oligomer possesses a much larger oscillator strength. The absorption and fluorescence spectra of the compounds have been recorded in chloroform. A reasonable agreement is obtained between TDDFT vertical transition energies and the (0,0) absorption and fluorescence bands. On one hand, the pattern of the aliphatic side chains does not affect the absorption and fluorescence maxima of the compounds. On the other hand, the replacement of aliphatic chains by phenyl or thiophene rings induces hypsochromic shifts in the absorption and fluorescence spectra. Finally, the fluorescence quantum yield and lifetime of the compounds in chloroform have been obtained. From these data, the radiative and nonradiative rate constants of the deactivation of the S1 state have been determined.     

吡唑啉衍生物的合成及应用研究进展

吡唑啉衍生物是一类应用广泛的重要五元含氮杂环化合物,在医药、农药等生物领域和其他非生物领域都具有非常重要的应用价值与广阔的应用前景.作者简单概述了吡唑啉衍生物的合成及其应用方面的研究进展.     

Triarylethene-based extended pi-systems: programmable synthesis and photophysical properties

[reaction: see text] On the basis of an efficient Pd-catalyzed triarylation to a vinylsilane platform, four types of structurally well-defined triarylethene-based extended pi-systems have been prepared very rapidly. From a compound library constructed by the present method, it was possible to find a number of interesting fluorescent materials, as well as interesting fluorescent properties such as aggregation-induced enhanced emission. A useful method for the rapid synthesis and property evaluation has also been developed.     

Carbazole-linked porphyrin dimers for organic light emitting diodes: synthesis and initial photophysical studies

Carbazole linked porphyrin dimers were synthesized in good yields via stepwise Suzuki coupling reactions using bromoporphyrins and borylated carbazoles as the precursors, the latter of which were synthesized via known procedures from biphenyl derivatives. For comparative purposes porphyrin-carbazole monomers were synthesized. Single layer organic light emitting diodes (OLEDs) were created to demonstrate the optical properties of these materials. Light emission from these carbazole substituted porphyrins showed better results compared to previously examined bromo substituted porphyrins with better electroluminescence and lower turn-on voltages. Dimers exhibited turn-on voltages of 3 V compared to 6 V for monomeric porphyrin-carbazoles.     

Permeable nonaggregating porphyrin thin films that display enhanced photophysical properties

Porphyrins bearing bulky alkoxyphenyl substituents at two of the four meso-positions and phenyl phosphonates at the other two have been prepared and used as building blocks for layer-by-layer assembly of conductive-glass-supported thin films via zirconium phosphonate chemistry. Thin-film characterization shows that the addition of sterically demanding 2,6-di(n-hexoxy)phenyl substituents to the meso-positions of the porphyrin skeleton can successfully prevent molecular aggregation. Both absorption and emission studies of multilayer thin films provide strong evidence that the new compounds have the ability to form thin films in which very little molecular (chromophore) interaction is present, relative to porphyrins that are not sterically hindered. Furthermore, the films are found to be permeable to selected small redox probes but blocking toward larger ones. Taken together, the sharp absorption spectra, increased emission yields, and permeability are expected to be advantageous for various materials-based applications such as photovoltaics and sensors.     

Novel core-expanded rylenebis(dicarboximide) dyes bearing pentacene units: facile synthesis and photophysical properties

Two synthetic routes for the benzannulation in the "bay"-region of rylenebis(dicarboximide)s leading to new pi-system-expanded chromophores are described. The first route follows a two-step approach: Suzuki coupling of bromo-substituted perylenebis(dicarboximide) with 2-bromophenylboronic acid, followed by palladium-catalysed dehydrobromination. The second route is best described as a palladium-assisted cycloaddition of benzyne, formed in situ, to the bay-region of the bromo-substituted rylene core. Two new types of core-expanded rylene dyes were synthesised: yellow dibenzocoronenebis(dicarboximide)s, absorbing at 490 nm, and a green dinaphthoquaterrylenebis(dicarboximide), which absorbs at 700 nm. These new chromophores are characterised by significant hypsochromic shifts of absorption, compared to their parent rylenebis(dicarboximide)s, excellent photostabilities and high fluorescence quantum yields.