Using 7-hydroxy-1-indanone as a prototype (I), which exhibits excited-state intramolecular proton transfer (ESIPT), chemical modification has been performed at C(2)-C(3) positions by fusing benzene (molecule II) and naphthalene rings, (molecule III). I undergoes an ultrafast rate of ESIPT, resulting in a unique tautomer emission (λ(max) ∼530 nm), whereas excited-state equilibrium is established for both II and III, as supported by the dual emission and the associated relaxation dynamics. The forward ESIPT (normal to proton-transfer tautomer species) rates for II and III are deduced to be (30 ps)(-1) and (22 ps)(-1), respectively, while the backward ESIPT rates are (11 ps)(-1) and (48 ps)(-1). The ESIPT equilibrium constants are thus calculated to be 0.37 and 2.2 for II and III, respectively, giving a corresponding free energy change of 0.59 and -0.47 kcal/mol between normal and tautomer species. For III, normal and tautomer emissions in solid are maximized at 435 and 580 nm, respectively, achieving a white light generation with Commission Internationale de l'Eclairage (CIE) (0.30, 0.27). An organic light-emitting diode based on III is also successfully fabricated with maximum brightness of 665 cd m(-2) at 20 V (885 mA cm(-2)) and the CIE coordinates of (0.26, 0.35). The results provide the proof of concept that the white light generation can be achieved in a single ESIPT system.
If there is a complex formed between TPTA and aromatic hydrocarbons in the ground state, there will be a potential shift in the reduction potential of aromatic hydrocarbons. This shift, however, was not significant even in good donor-acceptor pairs, such as the TPTA-benzophenone system. This assumption must therefore be valid. See ref 14.(34) J. T. Bowman and A.
Abstract:The electrochemical oxidation of oxalate at a platinum electrode in acetonitrile solutions as studied by cyclic and rotating-ring disk voltammetry and controlled potential coulometry shows an irreversible two-electron oxidation at ca. 0.3 V vs. SCE to CO2 with no intermediates detectable by these techniques. The oxidation of oxalate in the presence of several fluorescers (such as rubrene, 9, IO-diphenylanthracene, and the bipyridyl chelates of ruthenium(l1) and osmium(l1)) does not produce light, but emission characteristic of the fluorescer occurs during the simultaneous oxidation of the additive and oxalate. Studies of the conditions for emission in the presence of thianthrene and naphthalene lead to a mechanism for the oxidation of oxalate and the excitation process based on oxidation of oxalate to CzO4-., which undergoes rapid decomposition to COz and C02--. The C02-e can transfer an electron to the additive molecule to produce a radical anion, which can then undergo an ecl annihilation reaction with the electrogenerated radical cation.
Guanosine 3',5' cyclic monophosphate (cyclic GMP) levels in incubated slices of mouse cerebellum are increased 10-fold by glutamate and two-to three-fold by glycine or y-aminobutyric acid (GABA). Glutamate also produces a 10-fold increase in adenosine 3',5' cyclic monophosphate (cyclic AMP) in the same tissue. However, GABA decreases cyclic AMP levels 30-40 per cent, and glycine produces only a transient 50 per cent accumulation of this cyclic nucleotide. Theophylline slightly augments the accumulation of cyclic G M P produced by all three amino acids but markedly attenuates the accumulation of cyclic AMP produced by glutamate. In the absence of CaZf, none of the three amino acids has any effect on cyclic G M P levels, and glutamate produces only a 50 per cent rise in cyclic AMP levels. The decrease of cyclic AMP levels produced by GABA is not affected by theophylline or by the absence of CaZ+. These data suggest an involvement of both cyclic G M P and cyclic AMP in the neurochemical actions of glutamate, GABA and glycine.
A plasmonic sensor based on a dual-side polished photonic crystal fiber operating in a telecommunication wavelength range is proposed and investigated numerically by the finite element method (FEM). We study the effects of structural parameters on the sensor’s performance and analyze their tuning effects on loss spectra. As a result, two configurations are found when the analyte refractive index (RI) changes from 1.395 to 1.415. For configuration 1, an RI resolution of 9.39 × 10−6, an average wavelength sensitivity of 10,650 nm/RIU (the maximum wavelength sensitivity is 12,400 nm/RIU), an amplitude sensitivity of 252 RIU−1 and a linearity of 0.99692 are achieved. For configuration 2, the RI resolution, average wavelength sensitivity, amplitude sensitivity and linearity are 1.19 × 10−5, 8400 nm/RIU, 85 RIU−1 and 0.98246, respectively. The combination of both configurations can broaden the wavelength range for the sensing detection. Additionally, the sensor has a superior figure of merit (FOM) to a single-side polished design. The proposed sensor has a maximum wavelength sensitivity, amplitude sensitivity and RI resolution of the same order magnitude as that of existing sensors as well as higher linearity, which allows it to fulfill the requirements for modern sensing of being densely compact, amenable to integration, affordable and capable of remote sensing.
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