Steady-state and time-resolved spectroscopic investigations on the existence of stable methanol/AOT/n-heptane reverse micelles

Wang, Jia-Pei; Chen, Junsheng; Zhao, G.

doi:10.1016/j.jcis.2013.12.050

Cited by 12 publications

(4 citation statements)

References 43 publications

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“…The collective (rather than binary) nature of certain properties of confined water has been corroborated by a number of recent experimental and computational studies, suggesting that the core–shell description can be qualitatively instructive but is quantitatively an oversimplification. ,,, The behaviors of other solvents in nanoscopic volumes have chemical and technological implications that should also be explored. To a lesser extent than water, reverse micelles have been used to study confined nonaqueous solvents, and again the results are often interpreted within the construct of bulklike and interfacial populations. − However, the thermodynamics of phase separation of amphiphiles and the interior and exterior solvents place limits on the generality of reverse micelles as a testing platform for solvent dynamics.…”

Section: Introductionmentioning

confidence: 99%

Characterizing Solvent Dynamics in Nanoscopic Silica Sol–Gel Glass Pores by 2D-IR Spectroscopy of an Intrinsic Vibrational Probe

Huber

Massari

2014

J. Phys. Chem. C

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Porous sol–gel matrices were synthesized with IR-active Si–H vibrational chromophores integrated into the silica network. The Si–H vibrational mode was found to be highly accessible to solvents within the nanoscopic pores. Vibrational solvatochromism of the silane vibration was controlled largely by interactions between infiltrating solvents and the oxygen and hydroxide sites in the silica. Exchanging solvents in the silica matrices produced reversible solvatochromic shifts in some cases but led to irreversible shifts when strongly interacting solvents were tested, suggesting that a layer of solvent was not exchangeable. 2D-IR spectroscopy was used to monitor spectral diffusion and extract the homogeneous line widths of the Si–H mode for a range of infiltrating solvents as well as solvent-free aerogel samples. It was demonstrated that the silane vibration is sensitive to the nature of the infiltrating solvent, making these vibrationally active sol–gel films a general platform for solvent dynamics in nanoscopic confined volumes.

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Section: Introductionmentioning

confidence: 99%

Characterizing Solvent Dynamics in Nanoscopic Silica Sol–Gel Glass Pores by 2D-IR Spectroscopy of an Intrinsic Vibrational Probe

Huber

Massari

2014

J. Phys. Chem. C

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“…Experimentally, the lowest absorption peak of coumarin 153 in methanol exhibits a 0.35–0.44 eV solvatochromic red-shift compared to that in vacuum. ,, The TD-CASCI/MMPol electronic dynamics of the coumarin 153 dye in methanol solvent is simulated to resolve the absorption spectrum and solvatochromic shift. Coumarin 153 was placed in a box of 175 methanol molecules. , The solvation box was previously equilibrated using the Amber parm99SB force field. − …”

Section: Resultsmentioning

confidence: 99%

Time-Dependent Complete Active Space Embedded in a Polarizable Force Field

Liu

Jenkins

Wildman

et al. 2019

J. Chem. Theory Comput.

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Electron correlation and environmental effects play important roles in electron dynamics and spectroscopic observables of chemical systems in condensed phase. In this paper, we present a time-dependent complete active space configuration interaction (TD-CASCI) approach embedded in a polarizable force field, MMPol. The present implementation of TD-CASCI/MMPol utilizes a direct matrix-vector contraction, allowing studies of large systems. This scheme is used to study the solvatochromic shift of coumarin 153 in methanol. The TD-CASCI/MMPol approach captures the double excitation character in the excited state wave function and accurately predicts the solvatochromic red-shift of coumarin 153 dye within the experimental range, outperforming linear response time-dependent density functional theory. The effect of using different reference orbitals for the TD-CASCI/MMPol simulation is also investigated, highlighting the need for an unbiased treatment of all electronic states in the energy range of interest.

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“…Sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (aerosol OT or AOT) is the most common surfactant, which can form both aqueous and nonaqueous RMs without the aid of any co-surfactant. Numerous polar organic solvents, formamide, , dimethylformamide, glycerol, , glycols, , dimethyl sulfoxide (DMSO), acetonitrile, ,− methanol, ,,− and so on, have been tested for nonaq-RM formation. For most solvents, the signatures of RM droplet formation are convincing and supported by a gradual enlargement of the droplet size with an increase in the w s .…”

Section: Introductionmentioning

confidence: 99%

Anomalous Spectral Modulation of 4-Aminophthalimide inside Acetonitrile/AOT/n-Heptane Microemulsion: New Insights on Reverse Micelle to Bicontinuous Microemulsion Transition

Singha

Sahu

2018

J. Phys. Chem. B

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The behavior of acetonitrile/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/ n-heptane microemulsion, whether it remains as reverse micelle (RM) or bicontinuous microemulsion (BMC), has been controversial and even termed as a "problem system". Herein, we investigate the microemulsion using spectral and dynamical responses of a hydrophilic solvatochromic fluorophore 4-aminophthalimide (4-AP) at different w values (=[acetonitrile]/[AOT]). Interestingly, we found that emission parameters of 4-AP within the microemulsion vary differently at low and high w regimes. The quantum yield (ϕ) and lifetime (τ) of 4-AP first increase up to w = ∼1 and, thereafter, decrease upon a further increase in the w values. The emission maximum of 4-AP significantly shifts to a higher wavelength from 445 nm at w = 0 to 475 nm at w = 8. Interestingly, unlike aqueous RMs, the emission maximum at w = 1 matches with the emission maximum in neat acetonitrile and the emission maximum shifts to even longer wavelength at a higher w. Steady-state anisotropy also shows a break around w = 1; anisotropy decreases very sharply from w = 0 to 1 and, thereafter, remains nearly constant. Solvation dynamics becomes progressively faster with an increase in the acetonitrile content only in the low w regimes but remains almost independent of w after w > 2. All of the results collectively indicate that the morphology of the microemulsion may change at an intermediate w (∼1); below this, the system behaves like reverse micelles, and above this, the system may remain as BMC. The conjecture was further supported by dynamic light scattering measurements, where we observed a gradual increment of the average size at the low acetonitrile content (up to w = 1) but, thereafter, the size distribution becomes multimodal and sizes cannot be estimated correctly.

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Steady-state and time-resolved spectroscopic investigations on the existence of stable methanol/AOT/n-heptane reverse micelles

Cited by 12 publications

References 43 publications

Characterizing Solvent Dynamics in Nanoscopic Silica Sol–Gel Glass Pores by 2D-IR Spectroscopy of an Intrinsic Vibrational Probe

Characterizing Solvent Dynamics in Nanoscopic Silica Sol–Gel Glass Pores by 2D-IR Spectroscopy of an Intrinsic Vibrational Probe

Time-Dependent Complete Active Space Embedded in a Polarizable Force Field

Anomalous Spectral Modulation of 4-Aminophthalimide inside Acetonitrile/AOT/n-Heptane Microemulsion: New Insights on Reverse Micelle to Bicontinuous Microemulsion Transition

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