Search

Infrared and Raman spectra of the Mg2+ salt of poly(U) in D2O were recorded in the 1600-1800 cm−1 region and between 1 and 20C. The ir spectra showed a melting curve similar to the uv melting curves with a temperature of transition of about 6.5°C. This spectral change is assumed to be associated with the formation of the secondary structure of Mg2+-poly(U) in D2O at this temperature. Three double-helical and two triple-helical structures were used as inputs to compute the normal modes of vibration. A double-helical structure was found to give the best agreement with the observations. Knowledge of the C=0 eigenvectors, and of the expression for transition probability from quantum mechanics, was used to explain the so far unanswered question of H. T. Miles [(1964) Proc. Natl. Acad. Sci. USA 51, 1104–1109; (1980) Biomolecular Structure, Conformation, Function and Evolution, Pergamon, Oxford, pp. 251–264] as to why there is an increase in the ir vibrational wave number of a carbonyl band when that group is H-bonded to another polynucleotide chain in a helix. Such considerations also explain why a predicted band at about 1648 cm−1 is not to be seen in the ir spectra but is present in the Raman spectra. The model incorporating the CO transition dipole-dipole coupling interaction is able to explain also the observed higher intensity of the higher wave-number ir band. The experimental results demonstrate that the complete picture of vibrational dynamics of Mg2+-poly(U) in D2O is obtained only by looking simultaneously at ir and Raman spectra and not at only one of them. Weak ir bands were found to be as useful as the strong ones in understanding structure and vibrational dynamics. On the bases of our ir and Raman spectra, of the normal-mode analyses, and of the literature data, it is concluded that Mg2+-poly(U) in D2O is present in a double-helical structure at temperatures below the temperature of transition, whereby the uracil residues are paired according to arrangement (a) (see Fig. 1). This structure is rodlike and arises by refolding of one poly(U) chain. The computations show that no normal mode is associated with a single CO group vibration; all CO group vibrations are heavily mixed motions of various CO groups.

Nine NH acids with pK a values between 0 and 8.57 were studied by FTIR spectroscopy in the middle and far-infrared region. In addition, NMR spectra were taken and a semiempirical AMI analysis of the systems performed. Theproton potential in the NHN - - NHN hydrogen bonds is almost the same. The proton polarizability of these hydrogen bonds is almost independent of the pK a of the studied N acids. There is no relation between the position of the hydrogen bond vibration in the far-infrared region and the pK a of the N acids. Only with the pyrrol, the pyrazol, and the 4,(5)-methylimidazol systems these hydrogen bonds are linear. With all other systems these hydrogen bonds are more or less strongly bent. The position of the hydrogen bond vibrations v o calculated with the AMI procedure agrees well with the experimentally obtained values. The chemical shift of the hydrogen-bonded proton increases in proportion to the pK a values of the N acids.

The influence of the entropy on the proton transfer equilibria AH···B [Formula: see text]A–···H+B in the dimethylphosphinic acid (DMP)-N-base and in the methanesulfonic acid (MSA)-N-oxide hydrogen bonds is studied by 1H NMR spectroscopy as a function of the ΔpKa, i.e., the pKa of the base minus the pKa of the acid. It is shown that with increasing ΔpKa the proton transfers to the N-oxide acceptor. In the DMP + N-base family of systems, first the double-minimum proton potentials (ΔH = 0) occurs and only with further increasing ΔpKa do the POH···N [Formula: see text] PO–···H+N equilibria become symmetrical (ΔG = 0). ΔG and ΔH are connected by the Gibbs–Helmholtz equation, ΔG = ΔH –TΔS. Hence, the reason of this effect is the large negative interaction entropy term (ΔSI) arising from the large order around the polar structure, which shifts the equilibria strongly to the left-hand side. With the MSA-N-oxide hydrogen bonds a single-minimum proton potential was found. The minimum shifts with increasing ΔpKa from the donor to the acceptor of the O···H+···N hydrogen bonds. It is shown that with increasing ΔpKa the proton potential becomes on average symmetrical, whereas the proton is still largely on the left-hand side. This result is also explained by the large negative interaction entropy due to the order of the environment if the proton is at the acceptor B.Key words: entropy, hydrogen bonds, infrared, spectroscopy, proton transfer.

A new compound 3-(hydroxymethyl)-2,2‘-biphenol (HMBP) was synthesized. Complexes of this compound with three N-bases were studied by FTIR and 1H NMR spectroscopy. In the 1:1 mixture of HMBP and triethylamine (TEA) in chloroform, the complexes are formed completely. The hydrogen-bonded chain of these complexes shows large proton polarizability due to collective proton fluctuation. In acetonitrile the alcoholic group of HMBP is no longer bonded to the hydrogen-bonded chain. The rest of the hydrogen-bonded chain still shows proton polarizability. In the 1:1 mixtures of HMBP with a stronger base 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) the phenolic proton transfers to MTBD and is localized there. In chloroform the protonated MTBD is weakly bonded to HMBP via two other hydrogen bonds. In acetonitrile the complex dissociates. The complex between HMBP and urotropine is not formed completely and all hydrogen bonds within this complex are asymmetrical and weak.

Sixteen 1:1 dimethylphosphinic acid + N-base systems were studied in acetonitrile−chloroform (1:2) solutions as a function of the basicity of the N-bases. The complexes were measured in the middle infrared (MIR) and far-infrared (FIR) region at 20 °C and at −40 °C. The observed IR continua demonstrate that in the systems with the weaker bases an asymmetrical double minimum proton potential with the deeper well at the acid site is present. With increasing basicity the well at the base site becomes deeper and deeper and the proton potentials obtain a more symmetrical shape. The largest proton polarizability is attained with the system that shows the (on the average) most symmetrical proton potential, as indicated by the maximum bathochromic shift of the IR continuum. This shift toward lower wavenumbers is largest with the dimethylphosphinic acid + triallylamine complex. The most intense integrated absorbance of the IR continuum is also observed in this system. The characteristic intensity distribution at th...

Gramicidin A and C as well as their proton and Li+ complexes were studied by FT-IR spectroscopy. With an increasing number of hydrated and protonated channels, infrared continuous absorption is observed. It proves large proton polarizability due to very fast collective fluctuations and shifts of the excess proton in hydrogen-bonded single file water chains in the gramicidin channels. The infrared spectrum of the hydrated Li+ cation in the channels shows a continuum in the far-infrared region. This continuum is explained in terms of Li+ ion fluctuations and shifts between the electron lone pairs of two water molecules and at least three carbonyl O atoms of the backbone. The continuum indicates large Li+ polarizability of these channels. If the Li+-bonded system is polarized by an external electrical field, the diffusion of the Li+−water complex in field direction is favored.

Complexes of tris(2-ethylhexyl) phosphate (EHPO) with HAuCl4 and its hydrates with various amounts of water were studied by FT-IR spectroscopy. In the water free solution of HAuCl4 in EHPO homoconjugated PO···H+···OP hydrogen bonds with proton polarizability are formed. We demonstrate that in the 1:1 and 1:2 mixture with water only the H5O2+ species is present and no H3O+ species is formed. In the 1:1 mixture with water in addition to the H5O2+ species, 50% homoconjugated hydrogen bonds of protonated EHPO are still present. This homoconjugated hydrogen bond, as well as the central bond in H5O2+ shows large proton polarizability, as indicated by IR continua. In the 1:3 mixture of the homoconjugated complex with water a cyclic hydrogen-bonded system with a three-minima proton potential is present. The proton polarizability of this system is the largest, as indicated by a particularly intense IR continuum. In the case of the 1:4 mixture, a cyclic hydrogen-bonded arrangement with a four-minima proton potentia...

We synthesized and studied by Fourier transform infrared spectroscopy nine monosalts of diamides as models for the active side of aspartic proteinases. One compound, the monosalt of meta-aminobenzoic acid diamide of fumaric acid (m-FUM), shows the same biological activity as pepsin with regard to the splitting of peptide bonds of the Pro-Thi-Glu-Phe-Phe(4-NO2)-Arg-Leu heptapeptide. The monosalt of m-FUM forms with oxindole a complex in which the carboxylic acid group of the monosalt of m-FUM is strongly hydrogen bonded with the O atom of the peptide bond of oxindole. When one water molecule is added to this complex, the strong field of the carboxylate group destabilizes an O-H bond of the water molecule. The distorted water molecule attacks the carbon atom of the peptide group, and the water proton transfers to the peptide N atom. Simultaneously, the C-N bond of the amide group is broken. Hence it is demonstrated that the catalytic mechanism of aspartic acid proteinases is a base catalysis. The results show that for this catalytic mechanism there are sufficient carboxylic and carboxylate groups, as well as a water molecule in the correct arrangement. It was also demonstrated with other monosalts of dicarboxylic acids that well-defined steric conditions of the carboxylic acid and the carboxylate group must be fulfilled to show hydrolytic activity with regard to oxindole molecules.

From the tetrabutylammonium salt of the Mannich base N-oxide and 4,4′-bis-(tetramethylquanidine) azobenzene (BTA) 1:1 complexes with KClO 4 were prepared. All these substances were studied by osmometric measurements and by FTIR spectroscopy. The 1:1 complex of the Mannich base with KClO 4 is a monomer. The intramolecular K + bond shows still weak K + polarizability. The properties of these bonds are compared with Li + and particularly with Na + bonds showing larger cation polarizabilities. The 1:1 complex of BTA with KClO 4 exists in the acetonitrile-chloroform solution as dimer. The K + bonds in the complex show, however, no K + polarizability since the K + motions are strongly compensated to the π-electron motion in a conjugated system.

Fourier transform (FTIR) difference spectra of pepsin minus diazoacetylnorleucine methyl ester (DAN) or minus diazoacetyl-l-phenylalanine methyl ester (DAP) modified pepsin, respectively, demonstrated that Asp-215 is not deprotonated in pepsin. The FTIR difference spectrum of pepsin minus 1,2-epoxyparanitrophenoxypropane (EPNP) modified pepsin demonstrates that Asp-32 is present in pepsin as CO−2 anion. The position of the v(C  O) vibration demonstrates that no (O … H … O)− hydrogen bond between Asp-215 and Asp-32 is formed. Furthermore, no H3O+ is present in the active center. Studies of the complex of pepsin with the inhibitor pepstatin prove that the inhibitor removes the water from the active site and Asp-32 becomes protonated.

Two amino acids containing SH group (cysteine and homocysteine)+trimethylamine N-oxide systems were studied by FTIR and 1H NMR spectroscopy. This study demonstrates that cysteine and homocysteine ethylesters react with trimethylamine N-oxide. Immediately after mixing, SH⋯ON ⇋ S−⋯H+ ON hydrogen bonds with large proton polarizability are formed. Then a reaction proceeds resulting in the formation of corresponding disulphides. Trimethylamine N-oxide is present in biological systems. Thus, our results suggest that trimethylamine N-oxide may play a regulatory role in S-S bond formation in enzymes and other proteins.

The following complexes were investigated by Fourier transform difference spectroscopy: binary complexes of alcohol dehydrogenases from yeast (YADH) and horse liver (LADH) with nicotinamide adenine dinucleotide (NAD+) and adenosine (5')-diphospho(5)-beta-D-ribose (ADP-Rib); the binary complex of Zn2+-free YADH with NAD+, the ternary complex of LADH with NAD+ and 2,2,2-trifluoroethanol. After addition of NAD+ to YADH and LADH, protonation of the N1 atom of the adenine ring of NAD+ is observed. It is shown that this proton arises from the dissociation of the Zn2+-bound water. The interaction of the Zn2+ ion with water is very strong, since this interaction is not just an electrostatic interaction. If the Zn2+ ions are in a tetrahedral environment, a large covalent contribution also occurs. If ADP-Rib is present instead of NAD+, no protonation of the N1 atom of the adenine ring of ADP-Rib is found, which demonstrates that the positively charged nicotinamide ring favors the conduction of the positive charge. All these results confirm the mechanism of Branden et al. (1975): the Zn2+-bound water is split and the arising (OH)- deprotonates the alcohol. In the case of the ternary complex of LADH with NAD+ and 2,2,2-trifluoroethanol, we demonstrate that the alcohol is deprotonated and the alcoholate ion is bound directly to the Zn2+ ion. The conduction of the proton from the active site to the N1 atom of adenine occurs via a hydrogen-bonded chain with large proton polarizability due to collective proton motion. The nature and mechanism of this pathway are discussed on the basis of data from previous studies.

Based on the analysis of properties of protonic excitation and displacements in the hydrogen bonded molecular systems we proposed here a new model Hamiltonian and theory for studying the properties of nonlinear collective excitation and proton transfer resulting from the localized fluctuation of protons and the deformation of structure of heavy ionic sublattice owing to the protonic displacements.We give the equations of motion and corresponding solutions of solitons,discuss the features and meanings of these solutions and the advantages of our model,and explain completely motion of two kinds of defects and proton transfer in the hydrogen bonded molecular systems.

Hypophosphorous, phosphorous, phosphoric, and arsenic acids, pure and their aqueous solutions were studied by ir spectroscopy. Strong continuous absorptions observed with the pure liquid acids and with solutions containing less than one water molecule per acid molecule demonstrate that acid–acid hydrogen bonds in these systems are easily polarizable. The discussion of the PO and AsO bands as well as the discussion of the structure of the continuum demonstrates, however, that the degree of asymmetry of the energy surfaces in these hydrogen bonds is relatively large. It is shown that extended networks of such bonds exist. Due to the polarizability of these bonds, the proton motion in these bonds is strongly correlated. With addition of water, easily polarizable acid–water hydrogen bonds (I) [Formula: see text] (II) are formed. The energy surfaces in these hydrogen bonds are similar to those in the acid–acid hydrogen bonds. With further addition of water, proton boundary structure II receives noticeable weight, i.e., the degree of asymmetry of the energy surfaces in these bonds decreases due to addition of water molecules. The degree of symmetry of the energy surfaces in the acid–water hydrogen bonds increases in the series arsenic, phosphoric, phosphorous, and hypophosphorous acid.

HClO4 salts of N,N′-tetramethylalkanes (compounds 1–6) and of N,N′-tetraalkyl-o-xylildiamines (compounds 7–11) and HAuCl4 salts of N,N′-tetramethyl-o-xylildiamine-di-N-oxide (compound 12) and of o-xylildipiperidyl-di-N-oxides (compounds 13–14) were studied by nmr and ir spectroscopy. It is shown that in the compounds 3, 4, 5, and 7–11, long intramolecular [Formula: see text] hydrogen bonds with large proton polarizability and in compounds 12–14, short intramolecular [Formula: see text] hydrogen bonds with large proton polarizability are formed. The study of the compounds 1–6 shows that the most favorable conditions for the formation of the intramolecular easily polarizable hydrogen bonds occur with compound 4, i.e., if these hydrogen bonds are present in the 7-membered rings. In the case of compounds 7–14 it is shown that the continua usually observed with easily polarizable hydrogen bonds vanish when these bonds become screened from their solvent environments. Then, instead of continua only bands of the fundamental transitions are observed, with the long [Formula: see text] bonds in the region 2800–1800 cm−1 and with the short [Formula: see text] bonds in the region 1200–850 cm−1. This result demonstrates that for the occurrence of the ir continua, the interaction of the easily polarizable hydrogen bonds with their solvent environments is absolutely necessary. Furthermore, it is shown with the long as well as the short hydrogen bonds that the intensity of the continua decreases strongly with deuteration, demonstrating that in both cases the deuteron polarizabilities are much smaller than the proton polarizabilities of the hydrogen or deuterium bonds, respectively. From this observation it is concluded that the proton potentials of these structurally symmetrical hydrogen bonds are considerably deformed by their molecular surroundings.

Aqueous solutions of fourteen acids in the pKa region 0–4 were studied by ir spectroscopy as a function of concentration. All data are summarized in a table. The degree of dissociation was determined from bands of the anions. The removal of the protons from the anions decreases in the following series of the acids CF3COOH, H2CrO4, (HIO3), CF2HCOOH, HPO(OH)2, HSO4−, (HSeO4−), H2POOH, PO(OH)3, AsO(OH)3 (Table 1, columns 3 and 4). Continua indicate the formation of hydrogen bonds with large proton polarizabilities. In the case of H3PO3, H3PO4, and H3AsO4, the acid–acid hydrogen bonds are still polarizable although they have relatively asymmetrical proton potentials. The acid–water hydrogen bonds (I) [Formula: see text] (II) may show considerable proton polarizability, as indicated by strong continuous absorptions. The proton potential, and thus the proton polarizability of the acid–water hydrogen bonds, are discussed taking into consideration the intensity and the wave number range of the continuum (column 7), as well as the line width of the vibration with δ OH character (column 9). With increasing asymmetry of the hydrogen bonds, the continuum changes to the bands observed with asymmetrical hydrogen bonds. The sequence of acids in the series arranged according to the degree of dissociation is not the same as the sequence according to the intensity of the continuum and proton polarizability. This is explained by the fact that the proton polarizability is mainly determined by the shape of the proton potential, whereas the dissociation equilibrium is also influenced by entropy effects associated with hydrate structure formation.It is shown that the following molecular processes are of significance for the dissociation of the acids: the formation of acid–water hydrogen bonds with proton polarizability, whereby the weight of the polar proton-limiting structure [Formula: see text] increases with increasing addition of water molecules. Besides the shape of the proton potential, the entropy effects mentioned influence the degree of dissociation, too. Finally, the positive charge transfers from the acid–water into water–water hydrogen bonds, i.e., H5O2+ is formed.

Carboxylic acid-N base systems are studied in acetonitrile. The association equilibrium constants Ka and the proton transfer equilibrium constants KPT in the OH···N ⇄ O-···H+N bonds formed, are determined from IR spectra. The association constants Ka increase in proportion to the basicity of the hydrogen bond acceptors. The same is true with regard to the proton transfer constants. The OH ···N ⇄ O- ···H+N equilibria are shifted with increasing basicity to the right hand side. It is discussed that this shift is caused by an intrinsic effect as well as by an extrinsic one (interaction of the dipole of the hydrogen bond with its environment). A linear relation exists between log KPT and ⊿pKa (pKa of the protonated base minus pKa of the acid). 50% transfer of the protons to the N base is found at ⊿pKa = 2.6. As indicated by intense continua. these hydrogen bonds show large proton polarizability if the degree of asymmetry of their proton potentials is not too large.

The influence of neutral salts on the easily polarizable hydrogen bond of H5O2+ groupings in aqueous acid solutions is studied, using ir spectroscopy. The absorbance of the ir continuum, caused by the polarizable hydrogen bond in the H5O2+ groupings, usually decreases with increasing neutral salt concentration. This is explained by the polarization of the hydrogen bonds caused by local fields due to the neutral salt ions. The H+ becomes more or less trapped at one of the H2O of the H5O2+. The prominence of this effect increases with increasing cation field, i.e., from Cs+ to Li+, and is more pronounced with bivalent than with monovalent cations. The opposite effect is observed with tetraethylammonium chloride. The symmetry of H5O2+ groups is less strongly disturbed in the presence of neutral salts with ions with very large radii, i.e., small electrical fields, than in pure acid solutions. Considering the torsional vibration of the water molecules, it is finally shown that the hydrate structure network around the H5O2+ becomes disintegrated due to the presence of neutral salts.It is known from electrochemical investigations that the activity coefficient of the excess proton usually increases strongly due to the addition of neutral salts to acid solutions. The opposite is true with the addition of tetraethylammonium salt. Furthermore, the addition of neutral salt decreases the excess proton conductivity. All these observations are discussed on the basis of the ir spectroscopic results.

Aqueous solutions of 15 acids with pKa 3SO3−, HSO4−, ClO4−, HSeO4−, C6H5SO3−, NO3−. At very high concentrations (number of H2O/acid molecules, n 3O+ character of the vibrations of the H+OH2 groups increases with increasing n. For n > 1 the weight of proton limiting structure II increases and more and more protons transfer from the acid–water into the water–water hydrogen bonds, i.e., they are present in H5O2+ groupings which are embedded in the whole hydrate structure network. H3O+ vibrations are no longer found. The easily polarizable hydrogen bond in these groupings causes continuous absorption and the water molecules of these groupings cause broad bands. Of all acids studied, this group is the only cause of continuum in the more diluted solutions. The absorbance of the continuum per H5O2+ group at n = 2 increases in the series HClO4, CF3SO3H, H2SO4, H2SeO4, C6H5SO3H. This is because of the increasing polarity of the environment of the H5O2+ in this series of acids. The position of the water bands in solutions with n = 6 can be used to characterize the hydrogen bond acceptor strength of the anions. The H2O scissor vibration shows that it increases in the series AuCl4−, PtBr62−, PtCl62−, ClO4−, BF4−, CF3SO3−, J−, HSO4−, HSeO4−, C6H5SO3−, C7H7SO3−, Cl−. Finally molecular quantities which determine the pKa values of the acids (proton acceptor strength, hydrogen bond acceptor strength, and special interaction properties of the anions) are discussed.

IR spectra of aqueous solutions of PO4 3-, ADP3-, ATP4-, MgADP- and (MgADP- + PO4 3-) (in two cases hydrated layers) were plotted. The parameter for the investigation was the mole percent of protons relative to the anions. The other cations were sodium or potassium. The purpose of our work was to obtain a basis for understanding the results regarding the changes to the interactions in ATP systems on hydrolysis. The addition of protons to the different acceptors is discussed on the basis of the bands of the phosphate groups and of the base ring vibrations. The formation of easily polarizable hydrogen bonds could be demonstrated with the aid of an IR continuum. Such OH+···O bonds between hydrogen phosphate ions as well as NH+,,-N bonds form in the systems investigated. Thus the conditions for forming such bonds and the resulting intermolecular interactions will become evident in this work.

The K + , Na + and Ca 2+ form of excitable membranes of rat brain were investigated by infrared, ORD and CD spectroscopy. It is shown that with the K + form the conformatio of relatively large parts of the membrane proteins occurs as an antiparallel β structure. No β structure is found with the Na + and Ca 2+ form. In the presence of these ions the proteins are largely helical. This suggests that during the action potential, membrane proteins change their conformation depending on the cations shifted.

Symmetrical hydrogen bonds with a double minimum potential well or a largely flat potential are extremely easily polarisable, which leads to strong mutual interactions of such bonds and to interactions of the bonds with their environment. Particularly in the range of the rearrangement frequencies of the medium, the interactions depend to a marked extent on the fluctuation frequencies of the electromagnetic field and thus on the tunelling frequency of the proton in the hydrogen bond. On the other hand, the tunnelling frequency decreases due to the interactions. The correlation of the proton movements in two adjacent symmetrical hydrogen bonds and the resulting decrease of the tunnelling frequency is studied for the lowest group of levels. In addition, the decrease of the tunnelling frequency due to the effect of ion and dipole fields is calculated. In the tunnelling approximation the result depends in both cases on simple dimensionless parameters and indicates delay of the proton transfer in the bonds, but not complete hindrance. The lingering times in the potential wells are simply connected in both cases with the transition frequencies of the systems.

The serine phosphoric acid P-methylester (SPM) and the ethanol-amine phosphoric acid P-methylester (EPM) were synthesized as water soluble models for the functional groups of the corresponding phospholipids. Investigations were made of the aqueous solutions of these molecules as a function of deprotonation and protonation. An intramolecular, easily polarisable hydrogen bond occurs in the zwitterion of the SPM. The solutions of different salts of SPM were studied as well as the influence of counter ion pairs. Counterion pairs hardly influence these bonds. At about 50% deprotonation extremely easily polarisable intermolecular bonds form. At about 100% deprotonation of the zwitterion the hydrogen bonds observed are affected by the presence of CO2. The above is indicated by changes of the bands of the carboxylic and phosphate groups, and in particular by a continuous absorption in the infrared spectrum. During protonation of the EPM easily polarisable intermolecular POH+ ... OP hydrogen bonds form at first, but as protonation increases the solutions become acidic, that is, H5O2 + groupings form.

α-Amino and α-carboxylate group protected aspartate (Z-asp-OMe) and glutamate (Z-glu-OBZl) solutions in CH2Cl2 are studied as function of the addition of the respective salts by IR spectroscopy. The antisymmetrical stretching vibration of the -CO2 c- groups shifts to the position where v C = O of the acid groups is observed, indicating that both anions in the acid-anion complexes are strongly influenced by the proton. With the formation of these complexes a continuum arises preferentially in the region 1600-900 cm-1 demonstrating that the OH · · · O- ⇌ -O · · · HO bonds formed show great proton polarizability. These hydrogen bonds are short and the proton potential is probably a broad flat well. The degree of the formation of these hydrogen bonds is determined. Finally, it is discussed that positive charge can easily be translocated via such hydrogen bonds in protein molecules.

LONG-RANGE ordered elements of water structure of micrometre dimensions have long been suspected to exist near certain aqueous/solid interfaces. However, the evidence has been inconclusive1 and it has also been argued that such ordered elements of water structure exist near a glass surface from a comparison of the diffusion coefficients of the hydrogen ion from polarography and the sintered glass diaphragm cell method2–4,10. The pore size of the sintered glass varied between 4 and 15µm. The mobility of the hydrogen ion is known to be very sensitive to the structure of water5,6. We present here convincing evidence from an IR spectroscopic study of IM HC1 in porous silica that such long-range ordering effects exist near a quartz surface and that as a consequence the excess proton mobility is reduced. Such long-range effects have not been conclusively demonstrated previously. With acid solutions the interaction between the easily polarisable hydrogen bonds of H5O2+ groupings may favour such a long-range order and as the absorbance of the polarisable hydrogen bonds is sensitively influenced by all interaction effects this order may be indicated by changes of the IR continua.