Studies in partial molar volumes, partial molar compressibilities and viscosity B-coefficients of caffeine in water at four temperatures

Jahagirdar, D. V.; Arbad, Balasaheb R.; Walvekar, A.A.; Shankarwar, A. G.; Lande, Machhindra K.

doi:10.1016/s0167-7322(00)89019-4

Cited by 38 publications

(24 citation statements)

References 11 publications

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“…This is unusual for a neutral molecule like caffeine to show a negative dβ/dc slope. However, the slope dβ/dc is very small for caffeine indicating a low hydration number associated with caffeine, similar to that reported earlier [27]. It is known that dβ/dc is negative for structured water while it is positive for the non-structured one [33].…”

Section: Characterization Of Caffeine Dimer In Aqueous Solutionsupporting

confidence: 88%

“…A similar size distribution is observed when the concentration of the solution is increased from 45 mM to 900 mM. Since the radius of caffeine molecule is 3.76 Å [27] the observed hydrodynamic diameter of~1 nm in caffeine solution does not support the probability of formation of large caffeine aggregates over the studied temperature and concentration range.…”

Section: Characterization Of Caffeine Dimer In Aqueous Solutionsupporting

confidence: 55%

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Probing the Interior of Self-Assembled Caffeine Dimer at Various Temperatures

et al. 2011

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The self-assembly of non-toxic well-consumed small caffeine molecules into well-defined structures has important implications for future medical applications seeking to target the transport of small drugs in human body. Particularly, the solvation of the microenvironments of the self assembly ultimately dictates the interaction with the drug molecules and their therapeutic efficacy. We present femtosecond-resolved studies of the dynamics of aqueous solvation within self-assembled dimeric structure of caffeine molecules. We have placed small hydrophobic probes 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl) 4H-pyran (DCM), coumarin 500 (C500) into the caffeine dimer to enable spectroscopic examinations of the interior. While molecular modeling and NMR studies of the probes in the caffeine dimers reveal a well-defined location (stacked in between two caffeine molecules), dynamical light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, densimetric and sonometric experiments explore the structural evolution of the dimer upon complexation with the probes. We have extended our studies in various temperatures in order to explore structural evolution of the self assembled structure and consequently the dynamics of solvation in the interior of the dimer. Picoseconds/femtosecond resolved dynamics and the polarization gated spectroscopic studies unravel the hydration and energetics associated with activated viscous flow of the confined probes. Our studies indicate that the interior of the caffeine dimer is well-solvated; however, the dynamics of solvation is retarted significantly compared to that in bulk water, clearly revealing the dimers maintain some ordered water molecules. We have also explored the consequence of the retarded dynamics of solvation on the photo-induced electron transfer (ET) reaction of a model probe, 2-(p-toluidino) naphthalene-6-sulfonate (TNS) encapsulated in the dimer.

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Section: Characterization Of Caffeine Dimer In Aqueous Solutionsupporting

confidence: 88%

Section: Characterization Of Caffeine Dimer In Aqueous Solutionsupporting

confidence: 55%

Probing the Interior of Self-Assembled Caffeine Dimer at Various Temperatures

et al. 2011

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“…(4), we need to know the characteristic pore size and the dimensions of the diffusing molecule. The molecular dimension of our FITC-dextran (R m % 2 nm) [37,42], is nearly an order of magnitude larger than the dimensions of caffeine (0.376 nm) [43] and aspirin (0.41 nm) [32]. In highly packed colloidal systems, the simulations of Rintoul and Torquato [27] show that the characteristic pore size may be much smaller, 5-10% of the particle radius.…”

Section: Uncoated Filmsmentioning

confidence: 80%

Controlling surface porosity and release from hydrogels using a colloidal particle coating

Rosenberg

Dan

2010

Journal of Colloid and Interface Science

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“…Uncertainties in M 2 were assumed to be ±0.001g AE mol À1 for LiCl and ±0.0001 g AE mol À1 for RbCl, and CsCl. from table 1; j, reference [7]; d, reference [8]; r, reference [9]; N, reference [10]; ., reference [11,12]; M, reference [13]; }, reference [14];…”

Section: Resultsmentioning

confidence: 99%