Fluorescence characteristics of some hydroxyl-substituted naphthalenes (original) (raw)
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Fluorescence quenching of naphthalene and its substitutions by chloroethanes and -ethylenes
Journal of Luminescence, 1997
Fluorescence quenching of naphthalene and its substitutions by chloroethanes and -ethylenes were studied in solvents of different polarity. The mechanism of quenching was found to be purely dynamic and non-emissive charge-transfer exciplex mediated. The bimolecular quenching rate constant k, was dependent on the polarity of the solvent as against carbontetrachloride where it was dependent on the viscosity of the solvent.
Fluorescence quenching of substituted naphthalenes by inorganic anions
1995
Quenching of fluorescence of six substituted naphthalenes by inorganic anions have been studied. The quenching is dynamic with the involvement of electron transfer from the anion to the fluorophore in the quenching process. The free energy (.::1 G) and the activation energy {£.) of the electron transfer step has been estimated. Attempt is made to correlate the efficiency of quenching with these parameters.
Effects of Alkyl Substituents on the Excited States of Naphthalene: Semiempirical Study
The Journal of Physical Chemistry A, 2000
The effects of the successive addition of alkyl substituents (methyl and reduced rings) on the excited states of naphthalene are reported. The calculated electronic states of all the reduced derivatives with two, three, and four substituents are compared with the excited states of their methylated analogues. The excited states of several reduced derivatives with seven and eight substituents are also studied. The AM1 method was used to optimize the geometry of 57 naphthalene derivatives, and excited states were calculated with the ZINDO/S (INDO/S) method. ZINDO/S calculations on naphthalene gave excited states in better agreement with experimental results than with results of other semiempirical (CNDO/S and CNDOL) and ab initio (CIS, TD-HF, and TD-DFT) methods. Successive alkyl substitutions are accompanied by bathochromic displacements of the UV-visible bands, since the occupied orbitals are raised in energy more than the unoccupied orbitals. However, not all available substituent positions in naphthalene alter its orbital energy distribution in the same way when they are occupied by alkyl substituents. Distortion from planarity of the naphthalene skeleton of some reduced derivatives is the cause of "anomalous" bathochromic displacements of the absorption bands.
Applied Spectroscopy, 1992
Fluorescence emission spectra are reported for naphth[2',l',8',7': 4,10,51anthra [1,9,8cdeflcinnoline, benzo[lmnl[3,81phenanthroline (also called 2,7-diazapyrene), benz[4,10]anthrall,9,8cdeflcinnoline, naphtho[8,1,2hijlpyreno[9,10,1deflphthalazine, acenaphtho[1,2b]pyridine, benzo[alphenazine, indeno[1,2,3ijl[2,71naphthyridine, and indeno-[1,2,3ijlisoquinoline dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these measurements indicate that naphth[2',l',8',7':4,10,51anthra[1,9,8cdeflcinnoline exhibits some signs of probe character as evidenced by changing emission intensity ratios; however, numerical values did not vary systematically with solvent polarity. The effect of nitromethane and 1,2,4-trimethoxybenzene as selective quenching agents on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of roughly two-thirds of the alternant unprotonated PANHs studied to date. Emission intensities of the protonated PANHs remained essentially constant and were not affected by nitromethane. 1,2,4-Trimethoxybenzene, on the other hand, quenched the fluorescence emission of several unprotonated and all protonated PANHs examined.
Applied Spectroscopy, 1991
Fluorescence emission spectra are reported for naphth[2',l',8',7': 4,10,51anthra [1,9,8cdeflcinnoline, benzo[lmnl[3,81phenanthroline (also called 2,7-diazapyrene), benz[4,10]anthrall,9,8cdeflcinnoline, naphtho[8,1,2hijlpyreno[9,10,1deflphthalazine, acenaphtho[1,2b]pyridine, benzo[alphenazine, indeno[1,2,3ijl[2,71naphthyridine, and indeno-[1,2,3ijlisoquinoline dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these measurements indicate that naphth[2',l',8',7':4,10,51anthra[1,9,8cdeflcinnoline exhibits some signs of probe character as evidenced by changing emission intensity ratios; however, numerical values did not vary systematically with solvent polarity. The effect of nitromethane and 1,2,4-trimethoxybenzene as selective quenching agents on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of roughly two-thirds of the alternant unprotonated PANHs studied to date. Emission intensities of the protonated PANHs remained essentially constant and were not affected by nitromethane. 1,2,4-Trimethoxybenzene, on the other hand, quenched the fluorescence emission of several unprotonated and all protonated PANHs examined.
Photochemical & Photobiological Sciences, 2012
Naphthalenic compounds are a rich resource for designers of fluorescent sensing/switching/logic systems. The degree of ICT character in the fluorophore excited states can vary from negligible to substantial. Naphthalene-1,8;4,5-diimides (11-13), 1,8-naphthalimides (16) and 4-chloro-1,8-naphthalimides (15) are of the former type. The latter type is represented by the 4-alkylamino-1,8-naphthalimides (1). Whether ICT-based or not, these serve as the fluorophore in 'fluorophore-spacerreceptor' switching systems where PET holds sway until the receptor is bound to H +. On the other hand, 4-dialkylamino-1,8-naphthalimides (3-4) show modest H +-induced fluorescence switching unless the 4-dialkylamino group is a part of a small ring (5). Electrostatic destabilization of a non-emissive twisted ICT excited state is the origin of this behaviour. An evolution to the non-emissive twisted ICT excited state is responsible for the weak emission of the model compound 6 (and related structures 7 and 8) across the pH range. Twisted ICT excited states are also implicated in the switch 9 and its model compound 10, which are based on the 6-dialkylamino-3Hbenzimidazo[2,1-a]benz[d,e]isoquinolin-3-one fluorophore.
Applied Spectroscopy, 1991
Fluorescence emission spectra are reported for naphth[2',l',8',7': 4,10,51anthra [1,9,8cdeflcinnoline, benzo[lmnl[3,81phenanthroline (also called 2,7-diazapyrene), benz[4,10]anthrall,9,8cdeflcinnoline, naphtho[8,1,2hijlpyreno[9,10,1deflphthalazine, acenaphtho[1,2b]pyridine, benzo[alphenazine, indeno[1,2,3ijl[2,71naphthyridine, and indeno-[1,2,3ijlisoquinoline dissolved in organic nonelectrolyte solvents of varying polarity and acidity. Results of these measurements indicate that naphth[2',l',8',7':4,10,51anthra[1,9,8cdeflcinnoline exhibits some signs of probe character as evidenced by changing emission intensity ratios; however, numerical values did not vary systematically with solvent polarity. The effect of nitromethane and 1,2,4-trimethoxybenzene as selective quenching agents on both the unprotonated and protonated PANHs was also examined. Nitromethane was found to quench fluorescence emission of roughly two-thirds of the alternant unprotonated PANHs studied to date. Emission intensities of the protonated PANHs remained essentially constant and were not affected by nitromethane. 1,2,4-Trimethoxybenzene, on the other hand, quenched the fluorescence emission of several unprotonated and all protonated PANHs examined.
Journal of Photochemistry, 1976
A study is made of the quenching of fluorescence of a number of aromatic compounds by triphenyl derivatives of group V elements and by triethylamine in both non-polar and polar solvents. Whilst quenching is observed in many cases, the lack of correlation of the quenching rate with the ionization potential of the quencher suggests that this does not simply involve electron or charge transfer. Evidence is presented that a heavy atom effect involving the group V element -is also important. Further, a search has been made for evidence of exciplex formation in the quenching of azulene Sa fluorescence by a variety of compounds. However, no new emissions attributable to such a species are observed under the conditions studied. In addition, in polar solvents there is no evidence for an overall electron-transfer reaction in the quenching suggesting that if an intermediate charge-transfer or ion pair state is formed this may be of higher energy than the lowest singlet or triplet state, and may decay to yield one of these levels. lidroduction Excited singlet states of a variety of aromatic compounds have been shown to interact with amines [ 1 ] , inorganic anions [Z] , organo-derivatives of lead, tin and mercury [ 31, and various other inorganic, organic and organic and organometallic derivatives, as indicated by the quenching of the hydrocarbon fluorescence. The quenching is generally attributed to charge-transfer *Present address: Davy Faraday Research Laboratory of the Royal Institution, 21, Albemarle Street, Londc+n WlX 4BS (Gt. Britain).
Journal of Physical Organic Chemistry, 1997
Electronic absorption and steady-state fluorescence emission of seven 3,4-dihydro-1-(2-p-substituted benzylidene)naphthalenones (1-7) show sizable solvent dependence. The charge-transfer (CT) absorption maxima of these compounds in various solvents show a red shift for the electron-donating substituted compounds (1-5), whereas a blue shift is observed for compounds possessing electron-withdrawing substituents (6, 7). Excitation into the lowest energy absorption gives emission from the locally excited state, which relaxes to the emitting intramolecular charge-transfer state for compounds with strong electron-donating substituents (1-3) in hydroxylic solvents. However, in moderately polar solvents, dual emissions are observed for these compounds. No CT emission is observed for the compounds with moderate electron-donating substituents (3 and 4) or those with electron-withdrawing substituents (6 and 7). Compound 1 with an -N(CH 3 ) 2 substituent shows an excited-state dipole moment of 17 D.
Red shift in fluorescence of naphthalene doped by anthracene and perylene
Journal of Luminescence, 1999
The #uorescence in naphthalene is investigated systematically by doping it with di!erent amounts of anthracene and perylene with a view to obtain luminophors emitting at longer wavelengths. The #uorescence spectra of naphthalene luminophors are recorded on recording spectro#uorophotometer. It is observed that the addition of small amount of anthracene completely quenches the weak violet #uorescence of naphthalene and new anthracene like emission band appears in the #uorescence spectra of doped naphthalene. The intensity of anthracene like emission band is maximum at 10\ mol anthracene per mole naphthalene. The addition of perylene as another impurity not only quenches the anthracene like emission but also acts as wavelength shifter. Thus, the #uorescence spectra of naphthalene containing anthracene and perylene shows anthracene like emission followed by a broad tail towards red. The anthracene like emission is explained on the basis of #uorescence sensitization while red side of the spectrum is attributed to emission arising from charge transfer complex formed in the excited state.