Fluorescence Properties of p-Quaterphenyl and p-Quinquephenyl Derivatives in Liquid Solvents

Abstract

Absorption, fluorescence and emission anisotropy spectra, as well as quantum yields and fluorescence decay times of p-quaterphenyl (PQP), 4,4"'-bis-(2-butyloctyloxy)-p-quaterphenyl (BBQ), 2,5,2"",5""-tetramethyl-p-quinquephenyl (TMI) and 3,5,3"",5""-tetra-f-butyl-p-quinquephenyl (QUI) were investigated in several nonpolar and polar solvents. It was found that high quantum yield is accompanied by a short (not exceeding 1 ns) lifetime and considerable emission anisotropy in low viscosity solvents. For TMI and QUI, which incorporate as many as 5 phenyl groups, the quantum yield in dioxane is 0.98 and 0.97, respectively. In the case of molecules with 4 phenyl groups, the quantum yield is slightly lower, amounting to 0.91. Rotational motions of terminal phenyl groups cause a lower deactivation of the excitation energy of the singlet state S p the longer the linear molecule.

Time-Resolved Fluorescence Anisotropy of Bicyclo[1.1.1]pentane/Tolane-Based Molecular Rods Included in Tris(o-phenylenedioxy)cyclotriphosphazene (TPP)

“…They were essentially identical whether the sample was degassed or not. Results for 5 were reported before, − and our values agree.…”

“… a Quantum yield, estimated accuracy ±5%. b Lifetime, estimated accuracy ±0.05 ns. c The Stokes shift, calculated as the energy difference between the maxima of absorption and emission. d The solubility was too low for an accurate determination of ε. e Ref . f Ref . g Ref . h Ref . …”

Splitting the Ring: Impact of Ortho and Meta Pi Conjugation Pathways through Disjointed [8]Cycloparaphenylene Electronic Materials

“…Regardless, the fact that dis[8]-Th/Ph do not show signs of localized terphenyl, quinquephenyl (λ max ca. 370 and 390 nm), 44 or PET/PEB PL structure further indicated the hybrid fusion of radial and linear electronic character. Excitations are not localized to small segments of the molecules but are truly delocalized along both the linear PET/PEB segments and the radial CPP units.…”

UV-Fluorescence Correlation Spectroscopy of 2-Aminopurine

“…A limitation for all three solvents was that for times faster than 1 µs, the quality of the autocorrelation was not sufficient for analysis. (Kawski et al, 1996)] and 2AP [φ f =0.66 in water, ε=5400 cm -1 M -1 (Holmen etal., 1997)] (see Figure 3). The likely explanation is the high background from the organic solvents.…”