Synthesis,characterization, photophysical and electrochemical properties of oxygen bridged twisted heptatomic biphenyl substituted perylene diimides

The perylene diimide derivatives (s-THBPDI and d-THBPDI) bearing oxygen bridged twisty heptatomic biphenyl in the bay positions of the perylene core through acetylene bond were designed and synthesized. The photophysical properties of the functionalized dyes were investigated in solution and solid state by UV-vis and photoluminescence (PL) spectra. Their UV-vis and PL spectrum both exhibited the different concentration-dependent behaviors due to the difference of chemical structure. Moreover, cyclic voltammetry results indicated that the introduction of oxygen bridged twisted heptatomic biphenyl could decrease the LUMO energy level of the perylene diimide effectively and made it promising material in photoelectric devices.     

Synthesis and photophysical properties of lead phthalocyanines

This work reports on the synthesis and photophysical parameters of tetra-and octa-substituted new lead phthalocyanines. The complexes synthesized are: 1,4-(tetraphenoxyphthalocyaninato)lead (7a), 1,4-(tetra-tert-butylphenoxyphthalocyaninato)lead (7b), 2,3-(tetraphenoxyphthalocyaninato)lead (8a), 2,3-(tetra-tert-butylphenoxyphthalocyaninato)lead (8b), 2,3-octaphenoxyphthalocyaninatolead (9a) 2,3-[octakis(4-t-butylphenoxyphthalocyaninato)]lead (9b). Photophysical properties were studied for these complexes in a dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.70 to 0.88 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and <10 μs in the rest of the solvents) were observed due to the presence of heavy atom.     

Synthesis and photophysical properties of ferrocene-oligothiophene-fullerene triads

To promote photoinduced charge separation previously observed for the oligothiophene-fullerene dyads (nT-C60), we have designed an additional attachment with a strongly electron-donating ferrocene at the unsubstituted terminal site of the oligothiophene and synthesized two types of the ferrocene-oligothiophene-fullerene triads, Fc-nT-C60 directly linking the ferrocene to the oligothiophene and Fc-tm-nT-C60 inserting a trimethylene spacer between the ferrocene and the oligothiophene. For the central oligothiophene of the triads, a homologous series of quaterthiophene (4T), octithiophene (8T), and duodecithiophene (12T) are systematically examined. The cyclic voltammograms and electronic absorption spectra of Fc-nT-C60 indicate conjugation between the ferrocene and oligothiophene components. The emission spectra of Fc-nT-C60 measured in toluene demonstrate that the fluorescence of the oligothiophene is markedly quenched, as compared to that observed for the dyads nT-C60. This quenching is explained in terms of the involvement of intramolecular electron transfer in the photophysical decay process. The additionally conjugated ferrocene evidently contributes to the stabilization of charge separation states, thus promoting intramolecular electron transfer. This is corroborated by the observation that the emission spectra of the nonconjugated triads Fc-tm-nT-C60 are essentially similar to the corresponding dyads nT-C60.     

Synthesis and photophysical properties of phosphole-cored dendrimers

Phosphole-cored dendrimers having poly(benzyl ether) units through the third generation have been synthesized. The dendrimers display intense blue photoluminescence, the quantum yield increasing with the increasing generation of the dendron units. The optical properties are easily tuned by oxidation of the phosphorus atom of the phosphole ring.     

Discrete models for describing photophysical and thermodynamic properties of polar liquids

A number of properties of liquids with polar molecules are considered using water and ammonia as examples in the discrete approach, i.e., placing the centers of molecules on nodes of a particular lattice while assuming different orientations of the molecules. Different experimental properties are explained by different assumptions concerning the average values of pair orientations of adjacent molecules. Rather than using a uniform thermodynamic distribution over orientations to study fast processes related to the formation and migration of solvated electrons, a quasi-chemical approximation of the lattice gas model is used to calculate the thermodynamic properties of a liquid.     

Synthesis and photophysical properties of phenyl-sulfanylated chlororophyll derivatives

Chlorophyll derivatives that possessed a phenylsulfanyl group at the C3¹- or C3²-position were synthesized and their optical properties were investigated. Methyl 3¹-phenylsulfanyl-mesopyropheophorbide-a was prepared by substitutions of the corresponding C3¹-hydroxy-chlorin, methyl bacteriopheophorbide-d, with thiophenol in the presence of zinc iodide or of the corresponding C3¹-bromo-chlorin with thiophenol. The regioisomeric C3²-phenylsulfanyl-chlorin was obtained by addition of thiophenol to the C3-vinyl group of methyl pyropheophorbide-a in the presence of AIBN. Both the synthetic compounds gave similar electronic absorption and emission spectra in chloroform, but fluorescence quantum yield of the C3¹-sulfanyl-chlorin (0.18) was ca. 30% smaller than those of the C3²-sulfanyl-chlorin (0.25) and the C3-ethyl-chlorin (0.24). These observations were consistent with their fluorescence lifetime data. It is suggested that the heavy atom effect of a sulfur atom at the C3¹-position can tune photophysical properties of the chlorophyll derivatives.     

Synthesis and photophysical properties of phenothiazine-labeled conjugated dendrimers

A novel class of conjugated dendrimers bearing phenothiazines as peripheral groups and phenylenevinylene-group as a core has been synthesized through the Wittig-Horner reaction in moderate to good yield.     

Synthesis and photophysical properties of steroid-linked porphyrin-fullerene hybrids

[structure: see text] The photophysical properties of porphyrin-linked fullerene hybrids have generated significant interest, and a number of these hybrids synthesized by this group and others have been extensively characterized with respect to energy and charge-transfer processes that take place upon photoexcitation. Present studies of steroid-linked dyads demonstrate the extent to which through-bond effects operate in these systems.     

Synthesis and photophysical properties of tetrafluorophenyl-modified carbazole oligomers

A series of tetrafluorophenyl-modified oligo(3,6-carbazole ethynylene)s (CfCzCf, CfCz2Cf, CfCz3Cf, (CfCz)2Cf, and Cf2CzCf2) were synthesized by a Pd/Cu-catalyzed Sonogashira coupling reaction and fully characterized. Their photophysical and electronic properties as well as their thermal stabilities were investigated. It is noteworthy that these tetrafluorophenyl modified compounds showed relative thermal stabilities and low-lying HOMO levels ranging from −5.54 to −5.60 eV, which might be the promising candidates for hole-transporting materials in OLEDs.     

Synthesis and photophysical properties of nonbenzoid ended fluorophores

A series of pi-conjugated compounds (1-23) were successfully synthesized by the Sonogashira, Suzuki, and Wittig-Horner reactions. The structure-property relationship about photoluminescence based on these synthesized compounds was systematically discussed in detail. In addition, energy gaps between ground and excited states of these compounds, which were in good agreement with the experimental observation, were calculated by the semiempirical parametrized PM3 method. It was revealed that emission efficiency largely depends on molecular structure, aggregation type, and size of nanoaggregates.     

Synthesis and photophysical properties of metal anthraquinone phthalocyanine

A novel anthraquinone phthalocyanine Al(Ⅲ) 4 and Co(Ⅱ) 5 were synthesized and characterized by elemental analysis, IR, UV/ vis, 1H NMR, HPLC and MS. The photophysical properties of the two metal complexes were studied and compared by ?uorescence spectrum method.     

Synthesis and photophysical properties of electron-rich perylenediimide-fullerene dyad

An electron-rich perylenediimide-C60 dyad has been prepared to explore a new type of donor-acceptor system. Time-resolved absorption measurements in benzonitrile revealed unambiguous evidence for the formation of a charge-separated state consisting of perylene diimide radical cation and C60 radical anion via photoinduced electron transfer, showing a new class of artificial photosynthetic models in terms of charge separation.     

Synthesis and photophysical properties of fullerene-phthalocyanine-porphyrin triads and pentads

The synthesis and photophysical properties of several fullerene-phthalocyanine-porphyrin triads (1-3) and pentads (4-6) are described. The three photoactive moieties were covalently connected in an one-step synthesis through 1,3-dipolar cycloaddition to C(60) of the corresponding azomethine ylides generated in situ by condensation reaction of a substituted N-porphyrinylmethylglycine derivative and an appropriated formyl phthalocyanine or a diformyl phthalocyanine derivative, respectively. ZnP-C(60)-ZnPc (3), (ZnP)(2)-ZnPc-(C(60))(2) (6), and (H(2)P)(2)-ZnPc-(C(60))(2) (5) give rise upon excitation of their ZnP or H(2)P components to a sequence of energy and charge-transfer reactions with, however, fundamentally different outcomes. With (ZnP)(2)-ZnPc-(C(60))(2) (6) the major pathway is an highly exothermic charge transfer to afford (ZnP)(ZnP(.+))-ZnPc-(C(60)(.-))(C(60)). The lower singlet excited state energy of H(2)P (i.e., ca. 0.2 eV) and likewise its more anodic oxidation (i.e., ca. 0.2 V) renders the direct charge transfer in (H(2)P)(2)-ZnPc-(C(60))(2) (5) not competitive. Instead, a transduction of singlet excited state energy prevails to form the ZnPc singlet excited state. This triggers then an intramolecular charge transfer reaction to form exclusively (H(2)P)(2)-ZnPc(.+)-(C(60)(.-))(C(60)). A similar sequence is found for ZnP-C(60)-ZnPc (3).     

Synthesis and photophysical properties of N‐styrylazinones

N‐Styrylazinones and 1‐styrylbenzotriazine were synthesized, and their photophysical properties were investigated. (Z)‐ and/or (E)‐N‐Styrylazinones (or azine) 4 were prepared from the corresponding heterocycles 1 and benzaldehyde ( 3 ) by four methods. The absorption maxima of (Z)‐ and/or (E)‐ 4a ‐ 4j were measured in four solvents. Their absorption maxima showed a moderate dependence upon solvents. The absorption maxima of (Z)‐isomers were blue‐shifted as compared the corresponding (E)‐isomers. Emission maxima, fluorescence band half‐widths, 0,0 transition energies, Stokes shifts, and quantum yields of (Z)‐ and/or (E)‐ 4a, 4b, 4d, 4e and 4j were measured in organic solvents. The fluorescence spectra show moderate solvatochroism. The fluorescence properties of N‐styrylheterocycles vary with every heterocycles.     

Synthesis and photophysical properties of carbazole-based blue light-emitting dendrimers

A new class of highly fluorescent and stable carbazole-based dendrimers (1-5) that contain the ethynylbenzene and diethynylbenzene cores has been synthesized and characterized. They show very high extinction coefficients of absorption (A(max) approximately 328-353 nm) and high quantum yields of fluorescence (lambda(max) approximately 386-437 nm; Phi(F) approximately 0.72-0.89; tau(F) approximately 2.09-3.91 ns) in dichloromethane. The quantum yields of fluorescence of 1-5 in the solid state are equally high (lambda(max) approximately 385-422 nm; Phi(F) approximately 0.40-0.85). These data indicate their potential use as blue-emitting materials in organic light-emitting diodes (OLEDs).     

Synthesis,photophysical and antioxidant properties of carbazole-based bis-thiosemicarbazones

Research on Chemical Intermediates - Utilizing Schiff base condensation of the 9-ethylcarbazole-3,6-dicarbaldehyde and thiosemicarbazides, four new N-ethylcarbazole-based bis-thiosemicarbazone...     

Synthesis and photophysical properties of 2-styrylquinazolin-4-ones

trans-2-Styryl-substituted 3H-, 3-phenyl-, and 3-naphthylquinazolin-4-ones and their 6,7-difluoro derivatives were synthesized by condensation of appropriate 2-methylquinazolin-4-ones with aromatic aldehydes or by the transformation of the heterocycle of 2-methyl-3,1-benzoxazin-4-one under the action of benzylidenephenylamines.     

Synthesis, characterization and photophysical properties of benzidine-based compounds

The N-alkylation of the 3,3′-diaminobenzidine with innocent substituents leads to unusual properties. The emission of the benzidine core can be fine-tuned by subtle modifications, and the N-substitution with benzylic groups results in photoinduced exciplexes with distinct and increased emission. This compound constitutes the first example of intramolecular exciplex containing benzidine unit. We also show that these photoinduced processes could be modulated by proton input, and that the diprotonation of the benzidine core disrupted the intramolecular communication in the excited states with a concomitant inhibition of the ligand-centred fluorescence. Furthermore, upon photo-irradiation at 254 nm, semiquinone imine and quinone diimine systems are produced in CH₂Cl₂ of which the photolysis generates Cl radicals, which rapidly oxidize the tetraamine compounds.     

Synthesis and photophysical properties of new conjugated fluorophores designed for two-photon-excited fluorescence

[structure: see text] Novel elongated push-push fluorophores (e.g., 9) were synthesized by 2-fold Sonogashira or Wittigminus signHorner reactions. Modulation of the length and topology of the conjugated connectors allows tuning of their photophysical properties. In addition, their photoluminescence can be adjusted by playing on polarity. Derivatives combining enhanced two-photon absorption cross section (sigma2) in the visible red and high fluorescence quantum yield (Phi) have been obtained. Such fluorophores hold promise for nonlinear imaging of biological systems.