Relaxation Time Of Water Research Articles

Effects of co-solutes on the hydrogen bonding structure and dynamics in aqueous N-methylacetamide solution: a molecular dynamics simulations study

The effects of trimethylamine-N-oxide (TMAO), urea and tetramethyl urea (TMU) on the hydrogen bonding structure and dynamics of aqueous solution of N-methylacetamide (NMA) are investigated by classical molecular dynamics simulations. The modification of the water's hydrogen bonding structure and interactions is calculated in presence of these co-solutes. It is observed that the number of four-hydrogen-bonded water molecules in the solution decreases significantly in the presence of TMAO rather than urea and TMU. The lifetime and structural relaxation time of water–water and NMA–water hydrogen bonds show a strong increase with the addition of TMAO and TMU in the solution, whereas the change is nominal in case of urea solution. It is also found that the translational and rotational dynamics of water and NMA slowdown with increasing the concentration of these osmolytes. The slower dynamics of water and NMA is more pronounced in case of TMAO and TMU solution, as these co-solutes strengthen the average hydrogen bond energies between water–water and NMA–water, whereas urea has a little effect on the hydrogen bonding structure and dynamics of aqueous NMA solution. The calculated self-diffusion coefficient values for water and these co-solutes are in similar pattern with experimental observations.

NMR relaxation parameters from molecular simulations of hydrated inorganic nanopores

Nuclear magnetic resonance (NMR) relaxometry is a powerful technique to characterize diffusive motion of fluids in nanoporous to microporous media. Molecular simulations can be used to predict NMR relaxation parameters using a dipolar spin–spin correlation function. In this article, molecular dynamics simulations of water diffusion in anomalous 11 Å tobermorite, consisting of three slit pores and one gel pore of width ∼1.0 nm, have been performed. The spin–spin correlation function components corresponding to both 2D and quasi‐2D translation and rotation of water are presented. It was found that motion in the slit pores is highly correlated, leading to a significantly shorter relaxation time compared to bulk water. The correlation between the slit pores and the gel pore was found to be negligible compared to that within either the gel pore or the slit pore exclusively. Nevertheless, this correlation function can be useful in quantifying water diffusion within the slit pores, which occurs primarily through stochastic site jumping. It was found that stronger surface interaction leads to lower relaxation times, while the hydroxyls on the surface help further lower the water relaxation times. © 2014 Wiley Periodicals, Inc.

Water dynamics within a highly rigid sulfonated polyphenylene

Complex water molecule interactions within the confined environments of a sulfonated polyphenylene (sPP) ionomer were studied using 1H nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy. Multiple water environments were observed due to variations in hydrophilicity created by its structure, and chemical composition. Confined water properties are strongly dependent upon water content, degree of ionization, and temperature. Increasing the degree of sulfonation (DS) results in the creation of more water states and sites. The chemical shifts of water depend upon its environment with a smaller dependence on temperature. Confined water relaxation time T1 is than significantly lower bulk water and increases with temperature. Pulse field gradient (PFG) NMR studies reveals that water self-diffusion coefficients increase with. Water molecules diffuse faster in sPP than Nafion™, which implies that diffusion is facilitated by bundled hydrophilic pathways. Time-dependent FTIR reveals that bound water evaporates slower than unbound water during drying, which illustrates the difference of bulk and confined water within sPP ionomers. Hindered water evaporation is due to a reduction in the degrees of freedom for ion containing domains and mass transfer limitations at interfacial boundaries between hydrophobic and hydrophilic domains.

Use of low-field nuclear magnetic resonance to characterize water properties in frozen chicken breasts thawed under high pressure

The state of water in high-pressure-thawed and conventionally water bath-thawed chicken breasts was analyzed using low-field nuclear magnetic resonance. The influence of high-pressure thawing on water holding capacity, including thawing loss, cooking loss and expressible fluid, was evaluated. Thawing loss was significantly reduced (p 0.05). Higher thawing pressures lead to the T21 relaxation time being increased from 39.9 to 55.9 ms, and P21 increased from 89.5 to 94.9 %. Significant negative correlations (p < 0.01) were observed between the thawing loss and T21, T22, P21. These results indicate that high thawing pressures can transform the water from the loosely bound water fraction (T22) to a more tightly bound (T21) water fraction with the increase in water relaxation time.

Effects of high pressure processing on the thermal gelling properties of chicken breast myosin containing κ-carrageenan

The effects of high pressure processing (HPP) (0–400 MPa for 10 min, 0–20 min under 300 MPa) on the water holding capacity (WHC) and gel strength of chicken breast myosin containing 0.225% κ-carrageenan (W/V, 2.25 g/L relative to myosin solution) (myosin-K) and the thermal gelling mechanism were investigated. The results revealed that HPP at 100–400 MPa could significantly increase the WHC of myosin-K gels while decreasing the gel strength (P < 0.05). The turbidity, surface hydrophobicity and reactive sulfhydryl contents of the pressurized myosin-K increased significantly at 200–400 MPa (P < 0.05). Dynamic rheological measurements indicated that the thermal gelling ability of the pressurized myosin-K matrix gradually decreased as the pressure increased (100–400 MPa). Low-field nuclear magnetic resonance data suggested that HPP at 100–400 MPa might shorten the water relaxation time of the gel. The Fourier transform infrared spectroscopy data revealed that the hydrogen bonding interactions in the gels might weaken when subjected to 100–300 MPa but could be enhanced at 400 MPa. The scanning electron microscopy images revealed that HPP (300 MPa, 10 min) produced a dense, networked myosin-K gel structure with small cavities and thin cross-linked strands. Moreover, pressure levels were responsible for the above results. The protein in myosin-K could denature, unfold and aggregate under HPP (100–400 MPa), thus decreasing the thermal gelling ability of myosin-K matrix. The high WHC of the pressurized myosin-K gel was attributed to the enhanced hydrogen bonding and hydrophobic interactions, as well as the uniform and dense networked structure; the low gel strength might be ascribed to the low thermal gelling ability of pressurized myosin-K.

Molecular Dynamics Study of Nanoconfined Water Flow Driven by Rotating Electric Fields under Realistic Experimental Conditions

In our recent work, J. Chem. Phys. 2013, 138, 154712, we demonstrated the feasibility of unidirectional pumping of water, exploiting translational-rotational momentum coupling using nonequilibrium molecular dynamics simulations. Flow can be sustained when the fluid is driven out of equilibrium by an external spatially uniform rotating electric field and confined between two planar surfaces exposing different degrees of hydrophobicity. The permanent dipole moment of water follows the rotating field, thus inducing the molecules to spin, and the torque exerted by the field is continuously injected into the fluid, enabling a steady conversion of spin angular momentum into linear momentum. The translational-rotational coupling is a sensitive function of the rotating electric field parameters. In this work, we have found that there exists a small energy dissipation region attainable when the frequency of the rotating electric field matches the inverse of the dielectric relaxation time of water and when its amplitude lies in a range just before dielectric saturation effects take place. In this region, that is, when the frequency lies in a small window of the microwave region around ∼20 GHz and amplitude ∼0.03 V Å(-1), the translational-rotational coupling is most effective, yielding fluid velocities of magnitudes of ∼2 ms(-1) with only moderate fluid heating. In this work, we also confine water to a realistic nanochannel made of graphene giving a hydrophobic surface on one side and β-cristobalite giving a hydrophilic surface on the other, reproducing slip-and-stick velocity boundary conditions, respectively. This enables us to demonstrate that in a realistic environment, the coupling can be effectively exploited to achieve noncontact pumping of water at the nanoscale. A quantitative comparison between nonequilibrium molecular dynamics and analytical solutions of the extended Navier-Stokes equations, including an external rotating electric field has been performed, showing excellent agreement when the electric field parameters match the aforementioned small energy dissipation region.

Determination of Oxygen Permeability in Acrylic‐Based Hydrogels by Proton NMR Spectroscopy and Imaging

Polymer network membranes with a high capacity for water absorption are obtained by radical polymerization ofN‐[2‐(2‐hydroxyethoxy)ethyl]methacrylamide (HEEMAM). The permeability, solubility, and diffusion coefficients of oxygen in hydrogels are determined using nuclear magnetic resonance (NMR) methods based on the paramagnetic effect of dissolved oxygen gas on the proton spin‐lattice relaxation times of water, and the results are compared with those obtained with electrochemical procedures. The results of NMR measurements of oxygen transport coefficients in distilled water show excellent agreement with corresponding literature values. The results of the potentiostatic and NMR oxygen transport measurements in hydrogels are in reasonable agreement and support the viability of the NMR method.image

Bootstrap Calibration and Uncertainty Estimation of Downhole NMR Hydraulic Conductivity Estimates in an Unconsolidated Aquifer

Characterization of hydraulic conductivity (K) in aquifers is critical for evaluation, management, and remediation of groundwater resources. While estimates of K have been traditionally obtained using hydraulic tests over discrete intervals in wells, geophysical measurements are emerging as an alternative way to estimate this parameter. Nuclear magnetic resonance (NMR) logging, a technology once largely applied to characterization of deep consolidated rock petroleum reservoirs, is beginning to see use in near-surface unconsolidated aquifers. Using a well-known rock physics relationship-the Schlumberger Doll Research (SDR) equation--K and porosity can be estimated from NMR water content and relaxation time. Calibration of SDR parameters is necessary for this transformation because NMR relaxation properties are, in part, a function of magnetic mineralization and pore space geometry, which are locally variable quantities. Here, we present a statistically based method for calibrating SDR parameters that establishes a range for the estimated parameters and simultaneously estimates the uncertainty of the resulting K values. We used co-located logging NMR and direct K measurements in an unconsolidated fluvial aquifer in Lawrence, Kansas, USA to demonstrate that K can be estimated using logging NMR to a similar level of uncertainty as with traditional direct hydraulic measurements in unconsolidated sediments under field conditions. Results of this study provide a benchmark for future calibrations of NMR to obtain K in unconsolidated sediments and suggest a method for evaluating uncertainty in both K and SDR parameter values.

Dynamic Properties of Water Confined in Sephadex G15 Gel by Quasi-Elastic Neutron Scattering and Neutron Spin Echo Measurements

Abstract The dynamic properties of water confined in Sephadex G15 gel were investigated over the temperature range of 275–320 K at a hydration level h (= mass of water/mass of dry G15 gel) of 0.38, where both bound water melting at 258–268 K and unfrozen water are present, by using quasi-elastic neutron scattering (QENS) and neutron spin echo (NSE) techniques. The QENS data showed that, at 290 K, the water molecules perform local motions characterized by a diffusion coefficient Dlocal of (0.65 ± 0.05) × 10−5 cm2 s−1 and that the diffusion is limited to some volume estimated as a sphere with a radius of 4.4 Å. The Arrhenius plots of the relaxation time of water gave the activation energy of 44.2 ± 1.5 kJ mol−1, which is somewhat larger than the value (15–36 kJ mol−1) of water confined in MCM-41 C10 (pore diameter 21 Å). This finding suggests that water molecules in G15 gel are strongly bound to the hydroxy groups of the crosslinked substrates.

Correlated Dynamical Crossovers of the Hydration Layer of a Single-Stranded DNA Oligomer

Atomistic molecular dynamics (MD) simulations at different temperatures ranging from 160 to 300 K have been carried out to explore the correlated dynamical transitions of a single-stranded DNA (ss-DNA) oligomer with heterogeneous distribution of nucleobases, 5'-CGCGAATTCGCG-3', and that of its hydration water. The calculations reveal a distinct dynamical crossover of the DNA oligomer associated with abrupt changes of motions of its atoms at around 200-220 K. Importantly, it is found from calculated water diffusivities and relaxation times that the hydration water molecules also exhibit a crossover within 210-220 K. This indicates that the dynamical crossover of the DNA strand is coupled with that exhibited by its hydration water. In addition, another crossover point for the surface water molecules has been found around 180-185 K with the water layer exhibiting highly frozen dynamics. The rearrangement of hydrogen bond network that occurs due to population transition from two-coordinated to four-coordinated tetrahedrally arranged water molecules at the interface with lowering of temperature is found to be the microscopic origin of such correlated two-step dynamic crossovers of hydration water. Such modified hydrogen bonding results in transformation of hydration layer water structuring from high density to low density liquid under supercooled conditions.

InverseZ-spectrum analysis for spillover-, MT-, andT1-corrected steady-state pulsed CEST-MRI - application to pH-weighted MRI of acute stroke

Endogenous chemical exchange saturation transfer (CEST) effects are always diluted by competing effects, such as direct water proton saturation (spillover) and semi-solid macromolecular magnetization transfer (MT). This leads to unwanted T2 and MT signal contributions that lessen the CEST signal specificity to the underlying biochemical exchange processes. A spillover correction is of special interest for clinical static field strengths and protons resonating near the water peak. This is the case for all endogenous CEST agents, such as amide proton transfer, -OH-CEST of glycosaminoglycans, glucose or myo-inositol, and amine exchange of creatine or glutamate. All CEST effects also appear to be scaled by the T1 relaxation time of water, as they are mediated by the water pool. This forms the motivation for simple metrics that correct the CEST signal. Based on eigenspace theory, we propose a novel magnetization transfer ratio (MTRRex ), employing the inverse Z-spectrum, which eliminates spillover and semi-solid MT effects. This metric can be simply related to Rex , the exchange-dependent relaxation rate in the rotating frame, and ka , the inherent exchange rate. Furthermore, it can be scaled by the duty cycle, allowing for simple translation to clinical protocols. For verification, the amine proton exchange of creatine in solutions with different agar concentrations was studied experimentally at a clinical field strength of 3 T, where spillover effects are large. We demonstrate that spillover can be properly corrected and that quantitative evaluation of pH and creatine concentration is possible. This proves that MTRRex is a quantitative and biophysically specific CEST-MRI metric. Applied to acute stroke induced in rat brain, the corrected CEST signal shows significantly higher contrast between the stroke area and normal tissue, as well as less B1 dependence, than conventional approaches.

Gd-containing conjugated polymer nanoparticles: bimodal nanoparticles for fluorescence and MRI imaging.

Aqueous bifunctional semiconductor polymer nanoparticles (SPNs), approximately 30 nm in diameter (as measured from electron microscopy), were synthesised using hydrophobic conjugated polymers, amphiphilic phospholipids and a gadolinium-containing lipid. Their fluorescence quantum yields and extinction coefficients were determined, and their MRI T₁-weighted relaxation times in water were measured. The bimodal nanoparticles were readily taken up by HeLa and murine macrophage-like J774 cells as demonstrated by confocal laser scanning microscopy, and were found to be MRI-active, generating a linear relationship between T₁-weighted relaxation rates and gadolinium concentrations The synthesis is relatively simple, and can easily result in milligrams of materials, although we fully expect scale-up to the gram level to be easily realised.

Integration of surface and logging NMR data to map hydraulic conductivity

Geophysical NMR measurements yield direct detection of groundwater and provide sensitivity to hydraulic conductivity (K) via the measured NMR water content and relaxation times. The aim of this work is to map hydraulic conductivity over wide areas by leveraging complementary aspects of surface and logging NMR measurements. Surface NMR measurements have the advantage of being non-invasive and can image the basic NMR response of the subsurface over wide areas. NMR logging measurements, on the other hand, provide data at higher resolution and detail, but can only be acquired at sparse locations where boreholes are available. In practice, deriving robust estimates of K from either of these measurements is improved using site-specific calibration and comparison with hydrogeologic K measurements. We have developed a framework for calibrating and integrating these measurements, and this framework has been tested at three field sites in the United States. The framework can be divided into three components: (1) establishing the relationship between the logging NMR measurement and hydrogeologic measured K; (2) establishing the relationship between the logging NMR and surface NMR measurement; and (3) relating the surface NMR measurement to K and extending surface acquisition over a wide area. The data include an extensive collection of slug-tests, NMR logs, and surface NMR measurements, supplemented further by (DP) technologies, including a pressure/flow sensor DP-K tool and novel DP-NMR tool. Our results demonstrate the viability of this approach as well as the need for appropriate site- or region-specific calibration. Specifically, the relationship between the NMR logging measurement and surface NMR measurement can vary significantly in the presence of magnetic geology. We have also established that the method of well installation and logging can influence the estimated relationship between the NMR log and K measurement.

A morphological interpretation of water chemical exchange and mobility in cellulose materials derived from proton NMR T2 relaxation

Proton T2 relaxation times of water in cellulosic fibres have been interpreted using a 3-term average model. Motional and chemical exchange contributions to relaxation show opposing temperature behaviour, enabling the use of Arrhenius analysis to determine proton exchange rates and water rotational correlation times. Both parameters vary dramatically with extent of hydration, with chemical exchange dominating relaxation at saturated water contents. Interpretations are based on a morphological model with two types of accessible cellulose, at void surfaces and internally within the cellulose phase. In native cellulose fibres, the presence of crystalline fibrils with low internal accessibility leads to rapid proton exchange at low moisture contents. Regenerated cellulose fibres typically have lower crystallinity and higher internal accessibility, which results in slower exchange as result of migration of water between void and internal environments. Exchange behaviour in regenerated fibres is highly dependent on structural organisation, which depends on the manufacturing process.

Rapid multicomponent T2 analysis of the articular cartilage of the human knee joint at 3.0T

To determine the feasibility of using multicomponent-driven equilibrium single-shot observation of T1 and T2 (mcDESPOT) for evaluating the human knee joint at 3.0T and to investigate depth-dependent and regional-dependent variations in multicomponent T2 parameters within articular cartilage. mcDESPOT was performed on the knee joint of 10 asymptomatic volunteers at 3.0T. Single-component T2 relaxation time (T2single ), multicomponent T2 relaxation time for water tightly bound to proteoglycan (T2PG ) and bulk water loosely bound to the macromolecular matrix (T2BW ), and fraction of water tightly bound to proteoglycan (FPG ) were measured in eight cartilage subsections and within the superficial and deep layers of patellar cartilage. Statistical analysis was used to investigate depth-dependent and regional-dependent variations in parameters. There was lower (P = 0.001) T2single and T2PG and higher (P < 0.001) FPG in the deep than superficial layer of patellar cartilage. There was higher (P < 0.001) FPG on the weight-bearing surfaces than nonweight-bearing surfaces. There was higher (P < 0.001) T2single , T2PG , and T2BW on the trochlea and posterior medial and lateral femoral condyles than the patella, central medial and lateral femoral condyles, and medial and lateral tibia plateaus. Multicomponent T2 parameters of the articular cartilage of the human knee joint can be measured at 3.0T using mcDESPOT and show depth-dependent and regional-dependent variations.

The effects of changing water content, relaxation times, and tissue contrast on tissue segmentation and measures of cortical anatomy in MR images

Water content is the dominant chemical compound in the brain and it is the primary determinant of tissue contrast in magnetic resonance (MR) images. Water content varies greatly between individuals, and it changes dramatically over time from birth through senescence of the human life span. We hypothesize that the effects that individual- and age-related variations in water content have on contrast of the brain in MR images also have important, systematic effects on in vivo, MRI-based measures of regional brain volumes. We also hypothesize that changes in water content and tissue contrast across time may account for age-related changes in regional volumes, and that differences in water content or tissue contrast across differing neuropsychiatric diagnoses may account for differences in regional volumes across diagnostic groups.We demonstrate in several complementary ways that subtle variations in water content across age and tissue compartments alter tissue contrast, and that changing tissue contrast in turn alters measures of the thickness and volume of the cortical mantle: (1) We derive analytic relations describing how age-related changes in tissue relaxation times produce age-related changes in tissue gray-scale intensity values and tissue contrast; (2) We vary tissue contrast in computer-generated images to assess its effects on tissue segmentation and volumes of gray matter and white matter; and (3) We use real-world imaging data from adults with either Schizophrenia or Bipolar Disorder and age- and sex-matched healthy adults to assess the ways in which variations in tissue contrast across diagnoses affects group differences in tissue segmentation and associated volumes.We conclude that in vivo MRI-based morphological measures of the brain, including regional volumes and measures of cortical thickness, are a product of, or at least are confounded by, differences in tissue contrast across individuals, ages, and diagnostic groups, and that differences in tissue contrast in turn likely derive from corresponding differences in water content of the brain across individuals, ages, and diagnostic groups.

Two‐dimensional distribution of relaxation time and water content from surface nuclear magnetic resonance

ABSTRACTDevelopment in instrumentation and data analysis of surface nuclear magnetic resonance has recently moved on from one‐dimensional (1D) soundings to two‐dimensional (2D) surveys, opening the method to a larger field of hydrological applications. Current analysis of 2D data sets, however, does not incorporate relaxation times and is therefore restricted to the water content distribution in the subsurface.We present a robust 2D inversion scheme, based on the qt approach, which jointly inverts for water content and relaxation time by taking the complete data set into account. The spatial distribution of relaxation time yields structural information of the subsurface and allows for additional petrophysical characterization. The presented scheme handles separated loop configurations for increased lateral resolution. Assuming a mono‐exponential relaxation in each model cell, using irregular meshes, and gate‐integrating the signal, the size of the inverse problem is significantly reduced and can be handled on a standard personal computer.A synthetic study shows that contrasts in both the quantities – water content and relaxation time – can be imaged. Inversion of a field data set outlines a buried glacial valley and allows the distinguishing of two aquifers with different grain sizes, which can be concisely interpreted together with a resistivity profile. The impact of the anisotropic weighting factor and subsurface resistivity on the inversion result are shown and discussed. A comparison of the results obtained by the previously used initial value and time‐step inversion approaches illustrates the improved stability and resolution capabilities of the 2D qt inversion scheme.

Anion-Conductive Multiblock Aromatic Copolymer Membranes: Structure–Property Relationships

Anion-conductive multiblock copoly(arylene ether sulfone)s (mPES) were synthesized with different block lengths and ion-exchange capacities (IEC) to maximize ion conductivity and explore the relationship between chemical structure and morphology in anion-exchange membranes (AEM). Nuclear magnetic resonance (NMR) relaxometry was used to probe water mobility and domain size. The multiblock copolymers were synthesized by polycondensation of separately prepared hydroxy-terminated oligomers with fluoro-terminated oligomers. The polymers were made ion-conductive through selective chloromethylation of one of the two block types, followed by quaternization and hydroxide ion exchange. The resulting block structure, in which one type is hydrophilic and one type is hydrophobic, was designed to ensure a nanophase-separated morphology. The multiblock copolymers exhibited higher anion conductivity than their random copolymer counterparts at the same IEC. The multiblock copolymer that exhibited the highest anion conductivity was not the one with the highest IEC, but it was the one with the shortest NMR relaxation times for water, indicating a greater fraction of water interacts with the ionic polymer segments. Higher IEC values led to increased water absorption, an effective dilution of the ionic groups, and increased NMR relaxation times for water.

Dynamics of Hydration Water in Sugars and Peptides Solutions

We analyzed solute and solvent dynamics of sugars and peptides aqueous solutions using extended depolarized light scattering (EDLS) and broadband dielectric spectroscopies (BDS). Spectra measured with both techniques reveal the same mechanism of rotational diffusion of peptides molecules. In the case of sugars, this solute reorientational relaxation can be isolated by EDLS measurements, whereas its contribution to the dielectric spectra is almost negligible. In the presented analysis, we characterize the hydration water in terms of hydration number and retardation ratio ξ between relaxation times of hydration and bulk water. Both techniques provide similar estimates of ξ. The retardation imposed on the hydration water by sugars is ~3.3 ± 1.3 and involves only water molecules hydrogen-bonded (HB) to solutes (~3 water molecules per sugar OH-group). In contrast, polar peptides cause longer range perturbations beyond the first hydration shell, and ξ between 2.8 and 8, increasing with the number of chemical groups engaged in HB formation. We demonstrate that chemical heterogeneity and specific HB interactions play a crucial role in hydration dynamics around polar solutes. The obtained results help to disentangle the role of excluded volume and enthalpic contributions in dynamics of hydration water at the interface with biological molecules.

Unique Effects of Aerosol OT Lamellar Structures on the Dynamics of Guest Molecules

The behavior of lamellar structures of Aerosol OT (AOT) as hosts, vis-à-vis the flexible normal micelles and rigid nanochannels of Nafion membranes, has been investigated with two different fluorophores, [2,2'-bipyridyl]-3,3'-diol (BP(OH)2) and coumarin 102 (C102). Surprisingly, for BP(OH)2, a rise time is observed at intermediate emission wavelengths and not in the red edge of the fluorescence spectrum. A shoulder at 525 nm is observed in time resolved emission spectra (TRES) at initial times of BP(OH)2 in AOT lamellar structures. This feature is the signature of the monoketo (MK) tautomer, observed for the first time in a microheterogeneous medium. Also, the usually ultrafast single proton transfer in BP(OH)2 is retarded to an considerable extent in lamellar structures. The potential of this medium in promoting unusual intermediates is thus highlighted. This property may be ascribed to the rigidity of lamellar structures, compared to hosts such as regular micelles. However, studies using another fluorophore, coumarin 102 (C102), brings out the fact that these structures are significantly different from the rigid host, Nafion, as well. The absence of excited state proton transfer (ESPT) in this molecule in AOT lamellar structures indicates that it is not protonated, unlike in Nafion. Thus, the interfacial pH of lamellar structures is found to be significantly greater than that of Nafion nanochannels. From the time dependent Stokes shift (TDSS) of the emission spectra of C102, the relaxation time (0.85 ns) of interfacial water in lamellar structures is found to be an order of magnitude faster than that observed in Nafion nanochannels, in which H3O(+) ions have been substituted by different cations. Hence, this study demonstrates that AOT lamellar structures are rather unique hosts and that they behave very differently from conventional rigid and flexible hosts such as normal micelles and Nafion, respectively.