Twisted charge transfer processes of nile red in homogeneous solutions and in faujasite zeolite

Sarkar, Nilmoni; Das, Kaustuv; Nath, Dilip C.; Bhattacharyya, Kankan

doi:10.1021/la00013a048

Cited by 227 publications

(233 citation statements)

References 1 publication

Supporting

Mentioning

211

Contrasting

Unclassified

Order By: Relevance

“…purity higher than 99%. The peak wavelength of Nile red shows a red shift, and its quantum yield decreases when the solvent polarity increases because of a twisted intramolecular charge-transfer (TICT) excited-state [37]. For comparison, another polarity-sensitive dye, DCM, was used.…”

Section: Methodsmentioning

confidence: 99%

Evolution of the solvent polarity in an electrospray plume

Wang

Zenobi

2010

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Solvent polarity plays an important role in electrospray ionization-mass spectrometry (ESI-MS), one of the most widely used analytical methods for biochemistry. To have a comprehensive understanding of how solvent polarity affects ESI-MS measurements, we systematically investigated the polarity change in the ESI plume formed from an ethanol solution using laser-induced fluorescence (LIF) spectroscopy. Two solvatochromic dyes (i.e., dyes whose fluorescence emission is sensitive to solvent polarity), Nile red and DCM (4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran), were used as probes. The peak emission wavelengths of these two dyes exhibited significant red shifts (8 -12 nm) when the measuring spot was moved away from the spray tip and in radial direction in the plume, indicating a dramatic polarity change during shrinking of the droplets. The emission intensities were also measured with a polarity-insensitive dye as a reference. The results are consistent with the peak wavelength measurements. Two key mechanisms responsible for the change of solvent polarity in the plume were considered, water entrainment from the surrounding air and solvent evaporation. Furthermore, quantitative analysis of the solvent polarity change was performed by using the Lippert-Mataga polarity parameter ⌬f. The value of ⌬f reached 0.305-0.307 at the periphery of the ESI plume, which means that the solvent polarity in the smaller droplet is close to that of a mixture of 30% water and 70% ethanol (⌬f ϭ 0.307), even though the bulk solvent was ethanol containing less than 1% water as an impurity. (J Am Soc Mass Spectrom 2010, 21, 378 -385) © 2010 American Society for Mass Spectrometry E lectrospray ionization-mass spectrometry (ESI-MS) is widely used in many important fields, e.g., biochemistry, the food industry, and pharmacy, and is still under fast development. Despite its huge success, only relatively few fundamental studies on the mechanism of ESI have been undertaken: the different modes of the electrospray [1, 2], partitioning effects in sprayed droplets [3][4][5], size, charge, and mass changes of the droplets during solvent evaporation [6 -11], chemical equilibria in the electrospray process [12][13][14], and ion formation from the droplets [15][16][17][18][19][20] have been studied. However, more fundamental studies are still needed to make ESI-MS a totally reliable method for wider applications.In this work, we focus on one fundamental aspect of the ESI process, the solvent polarity in the ESI plume. As one of the most basic physical properties, solvent polarity controls the rates of chemical reactions [21,22] and chemical equilibria [23,24] in solution, which have been widely studied by ESI-based techniques [25][26][27]. Especially, solvent polarity can have significant effects on biomolecules. For example, the charge state of biomolecules in ESI mass spectra can vary with solvent polarity [28,29]. The solvent polarity also influences protein conformation [30], the stability of enzymes [31], and the structural ch...

show abstract

Section: Methodsmentioning

confidence: 99%

Evolution of the solvent polarity in an electrospray plume

Wang

Zenobi

2010

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

“…2,3 Nile Red is soluble over a very wide range of solvents and shows a large bathochromic absorbance shift with increasing solvent polarity (108 nm from n-hexane to water), 4 which is linear with that of the long-wavelength absorption band of the popular E T (30) probe. 5 The E T (30) value of a solvent is the energy of the intramolecular charge transfer transition of 2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinium) phenolate, which depends strongly on the polarity of the medium. 6 Nile Red in its ground state has low polarity, whereas in the excited state the molecules undergo an intramolecular transfer of an electron from the donor (dialkylamino group) to the acceptor group which is accompanied by a twist between the donor and the acceptor moieties.…”

Section: Introductionmentioning

confidence: 99%

“…6 Nile Red in its ground state has low polarity, whereas in the excited state the molecules undergo an intramolecular transfer of an electron from the donor (dialkylamino group) to the acceptor group which is accompanied by a twist between the donor and the acceptor moieties. This twisted intramolecular charge transfer (TICT) process gives a highly polar state, 5 for which the activation barrier decreases linearly with increasing E T (30). [7][8][9] Consequently, the excited state with a large dipole is stabilized in more polar solvents.…”

Section: Introductionmentioning

confidence: 99%

The use of Nile Red to monitor the aggregation behavior in ternary surfactant–water–organic solvent systems

Stuart¹,

Pas

Engberts

et al. 2005

J of Physical Organic Chem

219

212

View full text Add to dashboard Cite

‘Verbal overshadowing’, the phenomenon whereby the verbal reporting of a visual memory of a face interferes with subsequent recognition of that face, arises for the presentation of multiple faces following a single face description (Brown and Lloyd‐Jones, 2002). We examine the influence of description instructions on verbal overshadowing using the new multiple presentation paradigm. Participants were exposed to 12 to‐be‐remembered faces and then described (or not, in the control condition) another face. Half the participants received ‘piecemeal’ description instructions, encouraging veridical recall of particular features of the face, and half received ‘elaborative’ instructions which did not explicitly focus on particular facial features, and encouraged erroneous recall of the face. Subsequently, participants discriminated the original 12 faces from 12 distracters in a ‘yes/no’ recognition decision. Verbal overshadowing was evident for piecemeal, but not elaborative recall instructions. We interpret these findings within a ‘transfer‐inappropriate retrieval’ framework (Schooler et al., 1997). Copyright © 2002 John Wiley & Sons, Ltd.

show abstract

“…The elevated temperature reduces the 70 viscosity of the PB and promotes mixing. Nile Red has a hydrodynamic radius of approximately 0.5 nm, 21 making it suitable for tracing the flow of the larger PB.…”

mentioning

confidence: 99%