34 documents found, page 1 of 4
Triphenylamine-benzimidazole derivatives : synthesis, excited-state characteriz...
Pina, J.; Melo, J. Seixas de; Batista, Rosa Maria Ferreira; Costa, Susana P. G.; Raposo, M. Manuela M.The synthesis and comprehensive characterization of the excited states of four novel triphenylamine-benzimidazole derivatives has been undertaken in solution (ethanol and methylcyclohexane) at room temperature. This includes the determination of the absorption, fluorescence and triplet-triplet absorption spectra, together with quantum yields of fluorescence, internal conversion, intersystem crossing and singlet...
Synthesis and photophysical characterization of novel triphenylamine-benzimidaz...
Batista, Rosa Maria Ferreira; Pina, J.; Melo, J. Seixas de; Costa, Susana P. G.; Raposo, M. Manuela M.Research on organic luminescent materials has been intensely pursued due to their importance in technological applications related to signaling, fluorescent biosensory/chemosensory materials, molecular switches and organic light emitting diodes (OLEDs). Organic fluorophores such as triphenylamine and benzimidazole derivatives have attracted a particular attention owing to their high emission efficiency being wi...
Association of a Hydrophobically Modified Polyelectrolyte and a Block Copolymer...
Costa, Telma; Schillén, Karin; Miguel, Maria da G.; Lindman, Björn; Melo, J. Seixas deBy using absorption and fluorescence (steady-state and time-resolved) techniques, the interaction between a poly(acrylic acid) (PAA), randomly grafted with pyrene (Py) units (PAAMePy55), and a triblock copolymer of poly(ethylene oxide) and poly(propylene oxide) (EO20PO68EO20, P123) was investigated. From the fluorescence data, it is shown that upon addition of P123 a decrease of the (pyrene−pyrene, Py−Py) intra...
Complex Formation between a Fluorescently-Labeled Polyelectrolyte and a Tribloc...
Costa, Telma; Melo, J. Seixas de; Miguel, Maria da G.; Lindman, Björn; Schillén, KarinThe association between a randomly pyrene labeled PAA polymer (PAAMePy55) and a PEO−PPO−PEO triblock copolymer (P123) in aqueous solutions of different NaCl concentrations and pHs has been studied by means of dynamic light scattering (DLS) and steady-state fluorescence spectroscopy at 40 °C. At acidic pH values, in the low P123/PAAMePy55 molar ratio regime (i.e., at low P123 concentrations), the relaxation time...
Alternating Binaphthyl−Thiophene Copolymers: Synthesis, Spectroscopy, and Photo...
Pina, J.; Melo, J. Seixas de; Burrows, H. D.; Maçanita, A. L.; Galbrecht, F.; Bünnagel, T.; Scherf, U.The synthesis and a comprehensive spectroscopic and photophysical study are presented of four alternating binaphthyl−oligothiophene copolymers (DP: 10−15 repeat units) in solution at room and low temperature and in the solid state (thin films). Detailed results are presented on absorption, emission, and triplet−triplet absorption spectra together with all relevant quantum yields (fluorescence, intersystem cross...
Excited State Properties of Oligophenyl and Oligothienyl Swivel Cruciforms
Pina, J.; Melo, J. Seixas de; Burrows, H. D.; Galbrecht, F.; Bilge, A.; Kudla, C. J.; Scherf, U.A comprehensive study has been undertaken of the electronic spectral and photophysical properties of two oligophenyl (BPH and BPHF) and one oligothienyl (BTF) swivel cruciforms involving measurements of absorption, fluorescence, and phosphorescence spectra, quantum yields of fluorescence (phiF), phosphorescence (phiPh) and triplet formation (phiT), lifetimes of fluorescence (τF) and of the triplet state (τT), a...
A comprehensive study of the spectral and photophysical properties of arylthiop...
Melo, J. Seixas de; Pina, J.; Rodrigues, L. M.; Becker, R. S.A series of conjugated oligomers with rigid (fused-ring) structure, consisting in different polycyclic aromatic hydrocarbons (PAHs) possessing a single thiophene unit, here designated as arylthiophenes, were investigated in solution. For presentation clarity, the compounds were organized in two different groups. The first group includes the compounds where one, two, three and four benzene rings are added to a t...
Interplay of Electrostatic and Hydrophobic Effects with Binding of Cationic Gem...
Burrows, Hugh D.; Tapia, María J.; Silva, Cláudia L.; Pais, Alberto A. C. C.; Fonseca, Sofia M.; Pina, João; Melo, J. Seixas de; Wang, YujieUnderstanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly{1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl}copolymer (PBS−PFP) and cationic gemini surfactants α,ω-(CmH2m+1N+(CH3)2)2(CH2)s(Br-)2 (m-s-m; m = 12, s = 2, 3, 5, 6...
Spectral and Photophysical Studies of Poly[2,6-(1,5-dioctylnaphthalene)]thiophenes
Pina, J.; Melo, J. Seixas de; Burrows, H. D.; Galbrecht, F.; Nehls, B. S.; Farrell, T.; Scherf, U.A complete spectroscopic and photophysical study of three alternating naphthalene-α-thiophene copolymers was undertaken in solution (room and low temperature) and in the solid state (thin films in a Zeonex matrix). The study comprises absorption, emission, and triplet−triplet spectra together with quantitative measurements of quantum yield (fluorescence, intersystem-crossing, internal conversion, and singlet ox...
Electronic spectral and photophysical properties of some p-phenylenevinylene ol...
Melo, J. Seixas de; Pina, J.; Burrows, H. D.; Di Paolo, R. E.; Maçanita, A. L.A comprehensive photophysical and spectroscopic study of a new class of p-phenylenevinylene oligomers (PPV-trimers) possessing different alkyl and alkyloxy sidechain substituents and different end groups (aldehyde, CC, phenylene and anthracene units) was undertaken in solution at room temperature (293 K), low temperature (77 K) and in thin films. The study comprises absorption, emission and triplet-triplet abso...