Anion-Caffeine Interactions Studied by 13C and 1H NMR and ATR-FTIR Spectroscopy.

This work investigates the interactions of a series of 11 anions with caffeine by utilizing 13C and 1H NMR and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The aim of this study is to elucidate the molecular mechanisms of ion interactions with caffeine and to study how these interactions affect caffeine aggregation in aqueous solution. The chemical shift changes of caffeine 13C and 1H in the presence of salts provide a measure for anions' salting-out/salting-in abilities on individual carbon and hydrogen atoms in caffeine. The relative influences of anions on the chemical shift of individual atoms in the caffeine molecule are quantified. It is observed that strongly hydrated anions are excluded from the carbons on the six-member ring in caffeine and promote caffeine aggregation. On the other hand, weakly hydrated anions decrease caffeine aggregation by accumulating around the periphery of the caffeine molecule and binding to the ring structure. The ATR-FTIR results demonstrate that strongly hydrated anions desolvate the caffeine molecule and increase aggregation, while weakly hydrated anions have the opposite effects and salt caffeine into solution.

[1]  Bradley A. Rogers,et al.  Hofmeister Anion Effects on Thermodynamics of Caffeine Partitioning between Aqueous and Cyclohexane Phases. , 2016, The journal of physical chemistry. B.

[2]  J. Brady,et al.  Stacking and Branching in Self-Aggregation of Caffeine in Aqueous Solution: From the Supramolecular to Atomic Scale Clustering. , 2016, The journal of physical chemistry. B.

[3]  G. Graziano,et al.  On urea's ability to stabilize the globule state of poly(N-isopropylacrylamide). , 2016, Physical chemistry chemical physics : PCCP.

[4]  Michael A. Metrick,et al.  Hofmeister Ion-Induced Changes in Water Structure Correlate with Changes in Solvation of an Aggregated Protein Complex. , 2016, Langmuir : the ACS journal of surfaces and colloids.

[5]  Punidha Sokkalingam,et al.  Binding Hydrated Anions with Hydrophobic Pockets. , 2016, Journal of the American Chemical Society.

[6]  G. Graziano,et al.  On the effect of sodium salts on the coil-to-globule transition of poly(N-isopropylacrylamide). , 2015, Physical chemistry chemical physics : PCCP.

[7]  J. Brady,et al.  Hydration of Caffeine at High Temperature by Neutron Scattering and Simulation Studies. , 2015, The journal of physical chemistry. B.

[8]  S. Shimizu Caffeine dimerization: effects of sugar, salts, and water structure. , 2015, Food & function.

[9]  Sandip Paul,et al.  Understanding the role of temperature change and the presence of NaCl salts on caffeine aggregation in aqueous solution: from structural and thermodynamics point of view. , 2015, The journal of physical chemistry. B.

[10]  Michael A. Metrick,et al.  Hofmeister ion effects on the solvation and thermal stability of model proteins lysozyme and myoglobin , 2015 .

[11]  P. Cremer,et al.  An NH moiety is not required for anion binding to amides in aqueous solution. , 2015, Langmuir : the ACS journal of surfaces and colloids.

[12]  Tiancheng Mu,et al.  Molecular understanding of ion specificity at the peptide bond. , 2015, Physical chemistry chemical physics : PCCP.

[13]  B. Gibb,et al.  Anion complexation and the Hofmeister effect. , 2014, Angewandte Chemie.

[14]  J. Heyda,et al.  Effects of End Group Termination on Salting-Out Constants for Triglycine. , 2013, The journal of physical chemistry letters.

[15]  Sandip Paul,et al.  Effects of dilute aqueous NaCl solution on caffeine aggregation. , 2013, The Journal of chemical physics.

[16]  S. Srivastava,et al.  Ab initio and DFT studies of the structure and vibrational spectra of anhydrous caffeine. , 2013, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[17]  Tsung-Yu Wu,et al.  Hydration of cations: a key to understanding of specific cation effects on aggregation behaviors of PEO-PPO-PEO triblock copolymers. , 2013, The journal of physical chemistry. B.

[18]  J. Heyda,et al.  Reversal of the hofmeister series: specific ion effects on peptides. , 2013, The journal of physical chemistry. B.

[19]  E. Wilson Hofmeister Still Mystifies , 2013 .

[20]  P. Cremer,et al.  Cations bind only weakly to amides in aqueous solutions. , 2013, Journal of the American Chemical Society.

[21]  M. Himmel,et al.  Caffeine and sugars interact in aqueous solutions: a simulation and NMR study. , 2012, The journal of physical chemistry. B.

[22]  P. Cremer,et al.  Role of carboxylate side chains in the cation Hofmeister series. , 2012, The journal of physical chemistry. B.

[23]  J. Heyda,et al.  Molecular mechanisms of ion-specific effects on proteins. , 2012, Journal of the American Chemical Society.

[24]  R. K. Mitra,et al.  Probing the Interior of Self-Assembled Caffeine Dimer at Various Temperatures , 2012, Journal of Fluorescence.

[25]  P. Cremer,et al.  The Effects of Hofmeister Cations at Negatively Charged Hydrophilic Surfaces , 2012 .

[26]  B. Ninham,et al.  Hofmeister phenomena: an update on ion specificity in biology. , 2012, Chemical reviews.

[27]  J. Brady,et al.  Molecular dynamics simulation studies of caffeine aggregation in aqueous solution. , 2011, The journal of physical chemistry. B.

[28]  T. Beck A local entropic signature of specific ion hydration. , 2011, The journal of physical chemistry. B.

[29]  B. Deyerle,et al.  Effects of Hofmeister anions on the aggregation behavior of PEO-PPO-PEO triblock copolymers. , 2011, Langmuir : the ACS journal of surfaces and colloids.

[30]  B. Gibb,et al.  Anion binding to hydrophobic concavity is central to the salting-in effects of Hofmeister chaotropes. , 2011, Journal of the American Chemical Society.

[31]  P. Cremer,et al.  Specific anion effects on water structure adjacent to protein monolayers. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[32]  P. Cremer,et al.  Chemistry of Hofmeister anions and osmolytes. , 2010, Annual review of physical chemistry.

[33]  Luís M. N. B. F. Santos,et al.  1H NMR and molecular dynamics evidence for an unexpected interaction on the origin of salting-in/salting-out phenomena. , 2010, The journal of physical chemistry. B.

[34]  W. Kunz Specific Ion Effects , 2009 .

[35]  I. Marrucho,et al.  Towards an understanding of the mutual solubilities of water and hydrophobic ionic liquids in the presence of salts: the anion effect. , 2009, The journal of physical chemistry. B.

[36]  Luís M. N. B. F. Santos,et al.  Ion specific effects on the mutual solubilities of water and hydrophobic ionic liquids. , 2009, The journal of physical chemistry. B.

[37]  M. Record,et al.  Quantifying accumulation or exclusion of H+, HO-, and Hofmeister salt ions near interfaces. , 2008, Chemical physics letters.

[38]  Mikael Lund,et al.  Patchy proteins, anions and the Hofmeister series , 2008 .

[39]  A. Chilkoti,et al.  Effects of Hofmeister anions on the phase transition temperature of elastin-like polypeptides. , 2008, The journal of physical chemistry. B.

[40]  Mikael Lund,et al.  Specific ion binding to nonpolar surface patches of proteins. , 2008, Journal of the American Chemical Society.

[41]  M. Record,et al.  Thermodynamic origin of hofmeister ion effects. , 2008, The journal of physical chemistry. B.

[42]  Mikael Lund,et al.  Ion specific protein assembly and hydrophobic surface forces. , 2008, Physical review letters.

[43]  Mikael Lund,et al.  Specific ion binding to macromolecules: effects of hydrophobicity and ion pairing. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[44]  Jared D. Smith,et al.  The effects of dissolved halide anions on hydrogen bonding in liquid water. , 2007, Journal of the American Chemical Society.

[45]  P. Cremer,et al.  Specific ion effects on interfacial water structure near macromolecules. , 2007, Journal of the American Chemical Society.

[46]  P. Cremer,et al.  Effects of Hofmeister Anions on the LCST of PNIPAM as a Function of Molecular Weight. , 2007, The journal of physical chemistry. C, Nanomaterials and interfaces.

[47]  P. Cremer,et al.  Interactions between macromolecules and ions: The Hofmeister series. , 2006, Current opinion in chemical biology.

[48]  A. Amado,et al.  Computationally-assisted approach to the vibrational spectra of molecular crystals: study of hydrogen-bonding and pseudo-polymorphism. , 2006, Chemphyschem : a European journal of chemical physics and physical chemistry.

[49]  P. Jungwirth,et al.  Specific ion effects at protein surfaces: a molecular dynamics study of bovine pancreatic trypsin inhibitor and horseradish peroxidase in selected salt solutions. , 2006, The journal of physical chemistry. B.

[50]  B. Ninham,et al.  Hofmeister specific-ion effects on enzyme activity and buffer pH: Horseradish peroxidase in citrate buffer , 2006 .

[51]  J. M. Broering,et al.  Evaluation of Hofmeister effects on the kinetic stability of proteins. , 2005, The journal of physical chemistry. B.

[52]  P. Cremer,et al.  Specific ion effects on the water solubility of macromolecules: PNIPAM and the Hofmeister series. , 2005, Journal of the American Chemical Society.

[53]  B. Ninham,et al.  Hofmeister effects in biology: effect of choline addition on the salt-induced super activity of horseradish peroxidase and its implication for salt resistance of plants. , 2005, The journal of physical chemistry. B.

[54]  B. Ninham,et al.  Hofmeister series: the hydrolytic activity of Aspergillus niger lipase depends on specific anion effects. , 2005, The journal of physical chemistry. B.

[55]  S. Decatur,et al.  Spectroscopic evidence for backbone desolvation of helical peptides by 2,2,2-trifluoroethanol: an isotope-edited FTIR study. , 2005, Biochemistry.

[56]  K. D. Collins,et al.  Ions from the Hofmeister series and osmolytes: effects on proteins in solution and in the crystallization process. , 2004, Methods.

[57]  Barry W. Ninham,et al.  ‘Zur Lehre von der Wirkung der Salze’ (about the science of the effect of salts): Franz Hofmeister's historical papers , 2004 .

[58]  G. Pielak,et al.  Impact of protein denaturants and stabilizers on water structure. , 2004, Journal of the American Chemical Society.

[59]  S. Woutersen,et al.  Negligible Effect of Ions on the Hydrogen-Bond Structure in Liquid Water , 2003, Science.

[60]  A. Gräslund,et al.  A library of IR bands of nucleic acids in solution. , 2003, Biophysical chemistry.

[61]  B. Ninham,et al.  Ion specificity of micelles explained by ionic dispersion forces , 2002 .

[62]  Douglas J. Tobias,et al.  Ions at the Air/Water Interface , 2002 .

[63]  G. Martin,et al.  COMPLETE ASSIGNMENTS OF THE 1H, 13C AND 15N NMR SPECTRA OF CAFFEINE , 1995 .

[64]  M. Gil,et al.  Self-association of caffeine in aqueous solution: an FT-IR study , 1990 .

[65]  J. D. Taeye,et al.  Infrared Spectrum of Caffeine and its Hydrochloride Dihydrate , 1986 .

[66]  T. Zeegers-Huyskens,et al.  Infrared study of the interaction between caffeine and hydroxylic derivatives. , 1985, Journal of pharmaceutical sciences.

[67]  P. Borer,et al.  1H‐ and 13C‐nmr studies on caffeine and its interaction with nucleic acids , 1980, Biopolymers.

[68]  Franz Hofmeister,et al.  Zur Lehre von der Wirkung der Salze , 1891, Archiv für experimentelle Pathologie und Pharmakologie.

[69]  G. Klassen,et al.  Molecular modelling and NMR studies of the caffeine dimer , 1998 .

[70]  A. Shestopalova,et al.  Hydrophobic effect in biological associates: A Monte Carlo simulation of caffeine molecules stacking , 1989 .

[71]  V. Crescenzi,et al.  Thermodynamics of caffeine aqueous solutions , 1976 .

[72]  D. O. Jordan Physico-Chemical Properties of Nucleic Acids , 1950, Nature.