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Three-component complex of piperidine-ethanol, p-hydroxybenzoic acid and water studied by X-ray, Raman, FTIR and DFT
Accepted Manuscript Title: Three-component complex of piperidine-ethanol, p-hydroxybenzoic acid and water studied by X-Ray, Raman, FTIR and DFT Authors: Zofia Dega-Szafran, Kinga Roszak, Andrzej Katrusiak, Anna Komasa, Mirosław Szafran PII: DOI: Reference:
S0924-2031(17)30096-6 http://dx.doi.org/doi:10.1016/j.vibspec.2017.06.010 VIBSPE 2723
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5-4-2017 22-6-2017 25-6-2017
Please cite this article as: Zofia Dega-Szafran, Kinga Roszak, Andrzej Katrusiak, Anna Komasa, Mirosław Szafran, Three-component complex of piperidine-ethanol, phydroxybenzoic acid and water studied by X-Ray, Raman, FTIR and DFT, Vibrational Spectroscopyhttp://dx.doi.org/10.1016/j.vibspec.2017.06.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Three-component complex of piperidine-ethanol, p-hydroxybenzoic acid and water studied by X-Ray, Raman, FTIR and DFT Zofia Dega-Szafran, Kinga Roszak, Andrzej Katrusiak, Anna Komasa, Mirosław Szafran Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland
Corresponding author E mail address: [email protected] (Z.Dega-Szafran)
Graphical abstract Hydrogen-bonded piperidine-ethanol with p-hydroxybenzoic acid hydrate. X-Ray, Raman, FTIR and DFT studies Z. Dega-Szafran, K. Roszak, A. Katrusiak, A. Komasa, M. Szafran
HIGHLIGHTS
Piperidine-ethanol, p-hydroxybenzoic acid and water forms a crystalline adduct.
The crystalline complex is studied by X-ray, IR, Raman methods.
Its structure is optimized by the B3LYP/6-311++G(d,p) approach.
Charges delocalization are analyzed using the NBO method.
ABSTRACT A novel and unique crystalline three-component complex was formed by 2-(1piperidine)ethanol, p-hydroxybenzoic acid and water at the ratio 1:1:1. Its structure has been determined by single-crystal X-ray diffraction. This is an example of a hydrogen-bonded interaction between amino alcohol and benzoic acid molecules. Water acts as a bridge between molecules. The molecules are linked through medium-strong OH···O hydrogen bonds from 2.665(6) to 2.813(6) Å and NH···O one of 2.744(5) Å in length. The molecular structure of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate has been characterized by FTIR and Raman spectra and optimized at the B3LYP/6-311++G(d,p) level of theory. The potential energy distributions (PED) have been used to assign the vibrational spectra. Charge delocalization was analyzed using the natural bond orbital (NBO) methods.
Keywords: 2-(1-Piperidine)ethanol; p-Hydroxybenzoic acid; Hydrogen bonds; X-ray diffraction; Raman and FTIR spectra; DFT calculations. 1. Introduction
Aminoalcohols are an important class of organic compounds containing both amine and a hydroxyl functional groups in one molecule. Hence they act as hydrogen bond donor and acceptor, and open a wide range of possible hydrogen interactions. Simple aminoalcohols are used as solvents, synthetic intermediates and high boiling-point bases [1]. 2-(1Piperidine)ethanol [N-(2-hydroxyethyl)piperidine], PEt, belongs to the amino alcohol family and is a widely used adsorbent for removing acid gases, such as H2S, COS and CO2, from gas streams [2], as a base quencher to determine the efficiency of the decomposition of photoacid generators [3] and as a catalyst for enantioselective synthesis [4]. PEt is a base characterized by the dissociation constant of 9.63 at 25 oC [5], a proton-acceptor in tris[oxalato(2-)silicateand tris[oxalato(2-)germanate] complexes [6] and it is hydrogen-bonded to non-metal pentaborate cation [7]. Amino alcohols are added to some medical drugs, e.g. diclofenac, in order to improve its solubility [8]. The acid-base properties of 2-(1-piperidine)ethanol play an important role in the interactions between some molecules. In the present work we have synthesized a new adduct formed between PEt and p-hydroxybenzoic acid, HBA. HBA has two different proton-donor groups, COOH (pKa1 = 4.48) and OH (pKa2 = 9.11) [9]. HBA crystallizes as a monohydrate, where a pair of HBA molecules is linked through the O-H···O hydrogen bonds of 2.678 Å between carboxyl groups, forming dimers held together by the hydrogen bonds between the phenolic hydroxyl group and water molecules of 2.595 and 2.823 Å [10]. Various methods have been proposed for preparation of esters of amine alcohols and benzoic or carboxylic acids [11-15]. It has been shown by varying the amino alcohol that the rate of the
esterification is heavily dependent on its ability to activate the carboxylic acid by intermolecular hydrogen bonding. Recently, we have studied the effect of a hydroxyl group in hydroxybenzoic acid as an additional proton-donor substituent on the structure of complexes of dipolar ions (zwitterions, betaines) [16-27]. However only two of these complexes investigated crystallize with a water molecule [24,25]. Trigonelline complexes with HBA are linked into a cyclic dimer through the two water molecules [24], while water molecules play the role of a bridge between the DABCO di-betaine (HBA)2 complexes [25]. The presently synthesized 1:1:1 crystalline complex of 2-(1-piperidine)ethanol with phydroxybenzoic acid and water (1) has been characterized by X-ray diffraction, Raman and FTIR spectroscopy. We have optimized its structure at the B3LYP/6-311++G(d,p) level of theory in order to understand the aggregation of this first example of the interaction between the amino ethanol and substituted benzoic acid.
2. Experimental 2.1. Synthesis 3.02 g of 2-(1-piperidine)ethanol dissolved in 1 mL methanol was added to a solution of 3.22 g of p-hydroxybenzoic acid in 6 mL of methanol. The reaction mixture was left for 10 days at room temperature. The solid product (6.2 g) was filtered off, washed with chloroform and acetonitrile. The crude product of the adduct of 1-(piperidine)ethanol with phydroxybenzoic acid (1) was recrystallized from methanol, m.p. 137 oC. It crystallizes with one water molecule. Analysis for (C14H21NO4)H2O, m.wt 285.33: calc. %C 58.93, %H 8.12, %N 4.91, found %C 59.24, %H 8.13, %N 4.92.
2.2. Measurements
Single crystal X-ray data of 1 were measured on a KUMA KM4-CCD diffractometer. The structure was solved by direct methods using SHELXS, and refined on F2 by full-matrix leastsquares with the SHELXL programs [28]. The positions of H-atoms were located from geometry (hydroxyl 0.82 Å, methylene 0.97 Å, arene 0.93 Å and 0.91 Å in the tertiary amine) and in the difference Fourier maps for H2O. The anisotropic thermal parameters were refined for the non-H-atoms, and isotropic Uiso parameters for H atoms were linked to Ueq of their carriers. The crystal data, together with the details concerning data collection and structure refinement are given in Table S1. The crystal data have been deposited in the Cambridge Crystallographic Database Centre as a Supplementary publication CCDC 1529735 and in the Crystallography Open Database, COD 3000097. Molecular illustrations were prepared using programs Mercury CSD 3.3 [29]. Crystal data: [C7H16NO]+ [C7H5O3]- H2O: M = 285.33; crystal system: monoclinic, space group: P21/c; a = 14.532(4) Å, b = 8.0118(14) Å, c = 14.157(4) Å, = 113.84(3)o; V = 1507.7(6) Å3; Z = 4, Dc = 1.257 g cm-3, Rint = 0.0803; R1[I>2I] = 0.0512, wR1[I>2I] = 0.1167 for 10604 unique reflections. FTIR spectra were measured in Nujol and Fluorolube suspensions between KBr plates using a Bruker IFS 66v/S instrument, with the resolution of 2 cm-1. Each spectrum was accumulated by acquisition of 64 scans. The FTIR spectrum presented was obtained with the use of the split mull technique, which combined the spectrum from two parts, that in the range of 4000-1326 cm-1 from the spectrum measured in Fluorolube and that in the range 1326-400 cm-1 from the spectrum measured in Nujol. The Raman spectrum of crystalline sample was measured on a Bruker FRA-106/S instrument operating at the 1064 nm exciting line of Nd:YAG laser with the resolution of 4 cm-1. The spectrum was accumulated by acquisition of 512 scans. Elemental analysis was made using an Elemental Model Vario EL III instrument.
2.3. Computational details The DFT calculations were performed with the GAUSSIAN 09 program package [30]. The calculations employed the B3LYP exchange-correlation functional, which combines the hybrid exchange functional of Becke [31,32] with the gradient-correlation functional of Lee et al. [33] and the split-valence polarized 6-311++G(d,p) basis set [34]. The X-ray geometry of 1 was used as a starting point for the calculations. All calculated IR frequencies are real and confirmed that the optimized structure corresponds to a minimum energy. The potential energy distribution (PED) of the vibrational modes of the optimized molecule 2 was determined using VEDA 4 program [35,36]. Only the PED greater than 10% were considered. The local group coordinates (Sn) and their descriptions are given in Table S2 in Supplementary material. The natural bond orbital (NBO) [37] calculations were performed using the Gaussian 09 package at the B3LYP/6-311++G(d,p) level of theory.
3. Results and Discussion 3.1. Synthesis The reaction between 2-(1-piperidine)ethanol (PEt) and p-hydroxybenzoic acid (HBA) was carried out at a room temperature and molecules were not undergo the reaction of esterification, as it was shown in earlier studies [11-15]. PEt, forms a stable crystalline complex with HBA, and water at the 1:1:1 ratio (1).
3.2. Crystal structure The crystals of complex 1 are monoclinic of space group P21/c. Labeling of atoms is shown in Fig. 1. The bond lengths, bond and torsion angles are listed in Table S3. HBA transfers the proton from the carboxylic group to the nitrogen atom of the 2-(1-
piperidine)ethanol moiety, while the hydroxyl group of the ethanol moiety interacts with the second oxygen atom of the carboxylate group of HBA, and the PEtH+ cation is linked to the HBA- anion through the N(1)-H(1)∙∙∙O(3) and O(1)-H(O1)∙∙∙O(2) hydrogen bonds of 2.744(5) and 2.665(6) Å, respectively. The C(17)-O(2) and C(17)-O(3) bond lengths of the carboxylate group of HBA equal 1.266(1) and 1.278(1) Å confirm the presence of p-hydroxybenzoate in the crystal structure. Both carboxylate hydrogen atoms are double proton-acceptor to O(1)H and H2O, and to N(1)H and O(4)H, respectively (Table 1). The water molecule acts as a double proton-donor and links two PEt∙HBA complexes through O(1)∙∙∙H(W1)-O(W)H(W2)∙∙∙O(2) hydrogen bonds of 2.811(6) and 2.813(6) Å, respectively (Fig. 1, Table 1). The phenolic hydroxyl group O(4)-H(4) interacts with the O(3) oxygen atom of the carboxylate group of HBA of the neighboring complexes through the O(4)-H(O4)∙∙∙O(3) hydrogen bond of 2.693(6) Å and links the molecules into eight-membered cyclic aggregate described by the graph set R88(32) (Fig. 1) [38]. The independent unit of the PEt·HBA·H2O complex is asymmetric, whereas the whole crystal structure is centrosymmetric. The OH∙∙∙O and NH∙∙∙O hydrogen bonds form a 3-dimensional network (Fig. 2). The piperidine ring has a chair conformation with the CH2CH2OH group in an equatorial position.
3.2. Optimized structure
The structure of 2 is optimized at the B3LYP/6-311++G(d,p) level of theory and it is shown in Fig. 3. The geometrical parameters listed in Table S3 reproduce very well the crystal structure of 1. The calculated mean absolute difference (MAD) between the experimental and calculated bond lengths is 0.014 Å and bond angles is 0.81o. The main differences between 1 and 2 are observed in the torsion angles, especially in the carboxylate group of the HBA moiety and the plane of the aromatic ring (Table S3). The B3LYP functional has been
previously used as an efficient method for calculation of molecular structures and charge transfer properties [39-42]. Similarly as in 1, the 2-(1-piperidinium)ethanol action is joined to p-hydroxybenzoate anion though N-H∙∙∙O(3) and O(1)-H∙∙∙O(2) hydrogen bonds of 2.613 and 2.742 Å, respectively. However, the N∙∙∙O(3) distance in 2 is by 0.131 Å shorter than in 1, while the O(1)∙∙∙O(2) is longer by 0.077 Å (Table 1). The calculated energy for 2 is E(HF) = 978.549648 a.u. and dipole moment is = 5.36 D. The natural bond orbital (NBO) analysis has been proved to be an effective tool for chemical interpretation of electron density. It provide information about the interactions between electron-donors and electron-acceptors. It is also an efficient method for studying intra- and intermolecular bonding and interaction between bonds [37,43-46]. Table 2 summarizes the natural atomic charges of atoms in 2 and in pure 1-(2-piperidine)ethanol and p-hydroxybenzoic acid. Labeling of atoms is shown in Fig. 3. The protonation on N(1) reduces the decreasing the net charge in comparison to pure PEt, while the charge on O(1), engaged in the OH∙∙∙O hydrogen bond becomes more negative in complex 2 than in PEt. The charge on H(O1) is more positive in 2 than that on PEt. The charges on the oxygen atoms of the COOH and COO- groups in HBA and 2 are compared with the charges on atoms in HBA. The charges on O(2) and O(3) atoms are more negative in HBA moiety of 2 than in pure HBA.
3.3. Vibrational spectra
The experimental Raman and FTIR spectra of 2-(1-piperidinium)ethanol phydroxybenzoate hydrate, 1, and the theoretical IR spectrum of the isolated molecule 2, calculated at the B3LYP/6-311++G(d,p) level of theory and scaled by the factor of 0.9679
[47] are shown in Fig. 4. The wavenumbers of the experimental (ν̃exp), calculated (ν̃cal) and scaled (ν̃scal) bands are listed in Table S4. Generally, theoretical calculations overestimate the magnitudes of vibrational frequencies. The computed bands are shifted to higher wavenumbers relative to the experimental data, because the calculations are based on the harmonic frequency, while the experimental ones are based on the anharmonic frequencies. The difference follows also from the fact, that the experimental spectrum is recorded for compound 1 in the solid state, while the computations are made for vibrations of an isolated molecule 2. The distribution of the vibrational energy in internal coordinates (PED), defined and recommended by Keresztury and Jalsovszky [48], was used to assign vibrational bands in 2. According to the crystal structure there are four OH∙∙∙O hydrogen bonds of moderate strengths and one NH∙∙∙O hydrogen bond, in which both the ethanol OH, phenolic OH, water OH, carboxylate COO groups and piperidinium N+H atom are engaged (Fig. 1, Table 1). As a consequence, the OH and NH modes of the groups involved in the hydrogen bonds appear as a broad absorption in the 3400-2000 cm-1 region with submaxima at 3120, 2854, 2800, 2670, 2540 and 2320 cm-1, and they are difficult to separation. The shape of bands are probably due to an anharmonic coupling of the stretching AH with the stretching (AHB) vibrations, A – acid, B – base [49]. In the FTIR spectrum of 1 (Fig. 4b) the bands at 3524 and 3456 cm-1 are attributed to the asO(W)H(W) and sO(W)H(W) vibrations in the water molecule, respectively. In the Raman spectrum (Fig. 4a) no such absorption is observed. However, in the computed IR spectrum of 2 (Fig. 4d) the bands at 3766 and 3709 cm-1 are predicted to corresponds to O(W)H(W) and O(4)H(O4), respectively. The PED corresponding to these vibrations reveal pure OH stretching modes. In the calculated IR spectrum the bands at 3378 and 3321 cm-1 are predicted to be assigned to the O(1)H hydrogen bonding to the carboxylate group of HBA and to water molecule. The bands at 1598
and 692 cm-1 are predicted to O(W)H and O(W)H, and observed at 1629 and 705 cm-1, respectively. The strong band at 1387 cm-1 in the experimental spectrum of 1 is attributed to the O(1)H vibration and computed at 1421 and 1382 cm-1, while the O(4)H mode is predicted at 1152 cm-1 and observed at 1157 cm-1. Their contribution according to PED are found to be 64, 18 and 56 %, however all frequencies have PED values mixed with the other modes. In the theoretical spectrum of 2 the most intensive band at 2196 cm-1 corresponds only to the NH∙∙∙O(3) mode, the PED value is found to be 91%, while the band at 1563 cm-1 is assign to the NH vibration and that at 1524 cm-1 to the NH mode. In the experimental spectra the bands at 1553 cm-1 (Raman) and 1551 cm-1 (FTIR) are attributed to the NH vibration. The broad absorption in the 3400-2000 cm-1 region overlaps the CH and CH2 vibrations. They are visible in the Raman spectrum (Fig. 4a) in the range of 3200-2800 cm-1 and in the second derivative spectrum, d2 (Fig. 4c). In the latter spectrum, d2, the minima have the same wavenumbers as the maxima in the absorbance spectrum, but their relative intensities vary inversely with the square of the half-width of the absorbance bands, hence the broad bands due to OH∙∙∙O and NH∙∙∙O in the FTIR spectrum are not observed in the d2 spectrum [50,51]. The d2 spectrum proves that the broad absorption in the range of 3400-2000 cm-1 is attributed to OH and NH vibrations of the atoms engaged in the hydrogen bonds. Theoretically, the stretching CH modes of the phenyl ring are predicted in the higher wavenumbers region (3100-3046 cm -1) than the CH2 modes of the hetero-alicyclic ring and ethyl unit (3030-2908 cm-1). Some of them are visible in the extended d2 spectrum (Fig. 4c). The intensive bands at 1603 cm-1 (Raman) and 1599 cm-1 (FTIR) are assigned to the CC vibrations in the aromatic ring. Theoretically, the CC vibrations are predicted at 1593, 1583, 1563, 1490 and 1485 cm-1. In the IR spectrum of sodium p-hydroxybenzoate the band at 1590 cm-1 has been assigned to the CC vibration [44], while the bands at 1547 and 1416 cm-1 to
the asCOO and sCOO vibrations [52]. In the FTIR spectrum of 1 the asCOO vibrations at 1474 and 1367 cm-1 are observed. The presence of two asCOO bands can be explained of two different engagement in H-bonds of the carboxylate oxygen atoms, O(2) with the water molecule and the hydroxyl group of ethanol moiety, and O(3) with nitrogen atom of piperidinium units. The computed wavenumbers corresponding to the asCOO vibrations are predicted at 1485 and 1363 cm-1, however these modes are also mixed with the contributions of NH, H2O and CH2. The selected experimental and computed frequencies for the crystal and optimized structures are listed in Table S4. The mean absolute difference, MAD = calc(scaled) - exp/n) calculated for all scal frequencies is 11, while for selected ones (without without OH∙∙∙O, NH∙∙∙O and OH) is 4.
4. Conclusions
2-(1-Piperidine)ethanol, PEt, forms a crystalline hydrogen-bonded ionic pair complex with p-hydroxybenzoic acid, HBA. The water molecule acts as a bridge between complexes. This is the first example of interaction between aminoalcohol and benzoic acid molecules. The structure optimized at the B3LYP/6-311++G(d,p) level of theory reproduces well the aggregate form in the crystal. The solid state FTIR spectrum shows a broad absorption in the 3400-2000 cm-1 attributed to the stretching vibrations of OH···O and NH···O bands. The NBO analysis shows differences between the hydrogen-bonded PEt and HBA molecules, and these in pure components.
Acknowledgements The computations were performed at the Poznań Supercomputing and Networking Center and supported in part by PL-Grid Infrastructure.
References [ 1] M. Frauenkron, J.-P. Melder, G. Ruider, R. Rossbacher, H. Höke, Ethanolamines and propanolamines in Ullmans Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim, doi:10.1002/14356007 a10_001. [ 2] K. Tomizaki, S. Shimizu, M. Onoda, Y. Fujioka, Chem. Lett. 37 (2008) 516-517. [ 3] A.R. Pawloski, Ch. Nealey, P.F. Nealey, Chem. Mater. 13 (2001) 4154-4162. [ 4] F. Lutz, T. Igarashi, T. Kawasaki, K. Soai, J. Am. Chem. Soc. 127 (2005) 12206-12207. [ 5] S. Xu, F.D. Otto, A.E. Mather, Can. J. Chem. 71 (1993) 1048-1050. [ 6] O. Seiler, C. Burschka, M. Penka, R. Tacke, Z. Anorg. Allg. Chem. 628 (2002) 24272434. [ 7] M.A. Beckett, P.N. Horton, M.B. Hursthouse, D.A. Knox, J.L. Timmis, Dalton Trans. 39 (2010) 3944-3951. [ 8] C. Castelano, P. Sabatino, Acta Crystallogr. C 52 (1996) 1708-1712. [ 9] J. Hermans, S.J. Leach, H.A. Scheraga, J. Am. Chem. Soc. 85 (1963) 1390-1395. [ 10] K. Fukuyama, K. Ohkura, S. Kashino, M. Haisa, Bull. Chem. Soc. Jpn. 46 (1973) 804808. [ 11] W.G. Christiansen, S.E. Harris, United States Patent 2,243,694 (1941). [ 12] T.E. Jones, C.O. Wilson, J. Pharm. Sci. 42 (1953) 340-341. [ 13] T.E. Jones, C.O. Wilson, J. Pharm. Sci. 42 (1953) 342-343. [ 14] M. Robin, S.R. Schulte, United States Patent 3,758,547 (1973). [ 15] S. Breitenlechner, T. Bach, Z. Naturforsch. 61b (2006) 583-588. [ 16] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Przedwojska, M. Szafran, J. Mol. Struct. 649 (2003) 257-268. [ 17] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct.785 (2006) 160-166. [ 18] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 797 (2006) 82-91. [ 19] Z. Dega-Szafran, M. Jaskólski, M. Szafran, Pol. J. Chem. 81 (2007) 931-946. [ 20] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 844-845 (2007) 38-47. [ 21] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 875 (2008) 346-353. [ 22] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 923 (2009) 72-77.
[ 23] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 967 (2010) 80-88. [ 24] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 985 (2011) 219-226. [ 25] P. Barczyński, Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 994 (2011) 131-136. [ 26] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 994 (2011) 144-149. [ 27] P. Barczyński, Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 1000 (2011) 127-134. [ 28] G.M. Sheldrick (2008) Acta Crystallogr A 64 (2008) 112-122. [ 29] C.F. Macrae, P.R. Edgington, P. McCabe, E. Pidcock, G.P. Shields, R. Taylor, M. Towler, J. van de Streek, J. Appl. Crystallogr 39 (2006) 453-457. [ 30] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery, Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth, P. Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, O. Farkas, J.B. Foresman, J.V. Ortiz, J. Cioslowski, D.J. Fox, GAUSSIAN 09, Revision B.01, Gaussian, Inc., Wallingford CT, 2010. [ 31] A.D. Becke, J. Chem. Phys. 98 (1993) 5648-5652. [ 32] A.D. Becke, J. Chem. Phys. 107 (1997) 8554-8560. [ 33] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785-789. [ 34] W.J. Hehre, L. Radom, P.V.R. Schleyer, J.A. Pople, Ab Initio Molecular Orbital Theory, Wiley, New York, 1986. [ 35] M.H. Jamróz, Vibrational Energy Distribution Analysis; VEDA 4 Program, Warsaw, Poland, 2004-2010, http://smmg.pl. [ 36] M.H. Jamróz, Spectrochim. Acta A 114 (2013) 220-230. [ 37] A.E. Reed, L.A. Curtiss, F. Weinhold, Chem. Rev. 88 (1988) 899-926. [ 38] M.C. Etter, J.C. MacDonald, J. Bernstein, Acta Crystallogr. B 46 (1990) 256-262.
[ 39] A. Irfan, A.R. Chaudhry, A. G. Al.-Sehemi, M.S. Al.-Asiri, S. Muhammad, A. Kalam, J. Saudi Chem Soc. 20 (2016) 336-342. [ 40] A. Irfan, A. G. Al.-Sehemi, A.R. Chaudhry, S. Muhammad, M.S. Al.-Asiri, Optik 127 (2016) 10148-10157. [ 41] A. Irfan, A. Kalam, A.R. Chaudhry, A. G. Al.-Sehemi, S. Muhammad, Optik 132 (2017) 101-110. [ 42] A. Irfan, A. G. Al.-Sehemi, A.R. Chaudhry, S. Muhammad, Optik 138 (2017) 349-358. [ 43] A.E. Reed, F. Weinhold, J. Chem Phys. 78 (1983) 4066-4073. [ 44] S. Snehalatha, C. Ravikumar, I. Hubert Joe, N. Sekar, V.S. Jayakumar, Spectrochim. Acta A 72 (2009) 654-662. [ 45] D.M. Suresh, A. Amalanathan, S. Sebastian, D. Sajan, I. Hubert Joe, V. Bena Jothy, I. Nemec, Spectrochim. Acta A 115 (2013) 595-602. [ 46] R.P. Gangadharan, S. Sampath Krishnan, Acta Physica Polonica A, 125 (2014) 18-22. [ 47] M.P. Andersson, P. Uvdal, J. Phys. Chem. 109 (2005) 2937-2941. [ 48] G. Keresztury, G. Jalsovszky, J. Mol. Struct. 10 (1971) 304-305. [ 49] S. Bratos, H. Ratajczak, P. Viot in C.J. Dore, J. Teiseire (eds) Hydrogen Bond Liquids, Kluwer, Academic Press, 1991. [ 50] W.F. Maddams, M.J. Southon, Spectrochim. Acta A 38 (1992) 459-466. [ 51] G. Talsky, Derivative Spectrophotometry, VCH, Weinheim, 1994. [ 52] G.E. Dunn, R.S. McDonald, Can. J. Chem. 47 (1969) 4577-4588.
FIGURE CAPTIONS Fig. 1. Hydrogen bond interactions in an eigth-membered cyclic aggregate of 2-(1piperidinium)ethanol p-hydroxybenzoate hydrate (PEt∙HBA∙H2O) R88(32). Hydrogen bonds have been marked by dotted lines. The symmetry-independent atoms of one PEt∙HBA∙H2O unit, as well as some H-bond connections, have been labeled. Fig. 2. Crystal packing of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 1, viewed down [010]. H-atoms have been skipped for clarity. Fig. 3. The molecular structure of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 2, optimized by the B3LYP/6-311++G(d,p) approach. Hydrogen bonds have been marked by dotted lines. Fig. 4. The spectra of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate (a) Raman, (b) FTIR, (c) the second derivative IR spectrum and (d) the IR spectrum calculated by the B3LYP/6-311++G(d,p) approach and all wavenumbers scaled by 0.9679.
Fig. 1. Hydrogen bond interactions in an eigth-membered cyclic aggregate of 2-(1piperidinium)ethanol p-hydroxybenzoate hydrate (PEt∙HBA∙H2O) R88(32). Hydrogen bonds have been marked by dotted lines. The symmetry-independent atoms of one PEt∙HBA∙H2O unit, as well as some H-bond connections.have been labeled.
Fig. 2. Crystal packing of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 1, viewed down [010]. H-atoms have been skipped for clarity.
Fig. 3. The molecular structure of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 2, optimized by the B3LYP/6-311++G(d,p) approach. Hydrogen bonds have been marked by dotted lines.
3500 3000 2500 2000
1800
1600
1400
1200
1000
800
600
424
608
746
1233
623
869
1357
513 438
709
799
914
991
1077
1167
1271
2800
1151 1065
1235
1363
2900 1631 1600 1553 1507 1453
2859
2942
2955
3013
3048
3079
Absorbance 2nd deriv.
779
513 439
705
1009 991 949
1387
1599
624
1272 1234 1166 1079
1550
868 798
1508 1453
1629
3120 2854 2800 2670 2540 2320
3524 3456
Absorbance
(b)
1485
(d) 2196
3000
1583
3321
3378
3100
2942
3766 3709
Absorbance
524
1145
639
764
867
1081 1031
1274
2960
1553 1515 1440
3063
Raman activity
1387
1603
(a)
(c)
-1
400
Wavenumbers (cm )
Fig. 4. The spectra of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate (a) Raman, (b) FTIR (c) the second derivative IR and (d) the IR spectrum calculated by the B3LYP/6311++G(d,p) approach and all wavenumbers scaled by 0.9679.
Table 1. Experimental and calculated by the B3LYP/6-311++G(d,p) approach hydrogen-bonds dimensions (Å,°) in the complex of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate.
X-ray 1
B3LYP 2
D–H···A
DH
H···A
D···A
DHA
O(1)H(O1)∙∙∙O(2) O(W)H(W1)∙∙∙O(1)a O(4)H(O4)∙∙∙O(3)b O(W)H(W2)∙∙∙O(2) N(1)H(1)∙∙∙O(3)
0.820 0.820 0.820 0.820 0.910
1.845 2.024(9) 1.875 2.095(5) 1.859
2.665(6) 2.811(6) 2.693(6) 2.813(6) 2.744(5)
179.26 159.62 176.67 146.00 163.49
O(1)H(O1)∙∙∙O(2) N(1)H(1)∙∙∙O(3) O(W)H(W2)∙∙∙O(2)
0.982 1.096 0.982
1.763 1.536 1.774
2.742 2.613 2.744
174.09 166.03 168.81
Symmetry codes: a x, 1+y, z; b x, 1.5y, 0.5+z.
Table 2. Selected natural atomic charges (NBO) (e) for atoms in the complex of 2-(1piperidine)ethanol with p-hydroxybenzoic acid (2), 2-(1-piperidine)ethanol (PEt), and phydroxybenzoic acid (HBA). Atoma N(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) O(1) H(O1) H(1) a
2 -0.5328 -0.1558 -0.4079 -0.3812 -0.4028 -0.1775 -0.1833 -0.0521 -0.7644 0.4985 0.4774
PEt -0.6001 -0.1625 -0.3886 -0.3812 -0.3883 -0.1698 -0.1943 -0.0280 -0.7399 0.4653 -
Labels of atom in Fig. 3.
Atoma C(11) C(12) C(13) C(14) C(15) C(16) C(17) O(2) O(3) O(4) H(O3) H(O4)
2 -0.1765 -0.1409 -0.2902 0.3475 -0.2600 -0.1435 0.8113 -0.8037 -0.7752 -0.6723 0.4663
HBA -0.1996 -0.1284 -0.2847 0.3414 -0.2537 -0.1376 0.7881 -0.6089 -0.6938 -0.6622 0.4850 0.4699
S0924-2031(17)30096-6 http://dx.doi.org/doi:10.1016/j.vibspec.2017.06.010 VIBSPE 2723
To appear in:
VIBSPE
Received date: Revised date: Accepted date:
5-4-2017 22-6-2017 25-6-2017
Please cite this article as: Zofia Dega-Szafran, Kinga Roszak, Andrzej Katrusiak, Anna Komasa, Mirosław Szafran, Three-component complex of piperidine-ethanol, phydroxybenzoic acid and water studied by X-Ray, Raman, FTIR and DFT, Vibrational Spectroscopyhttp://dx.doi.org/10.1016/j.vibspec.2017.06.010 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Three-component complex of piperidine-ethanol, p-hydroxybenzoic acid and water studied by X-Ray, Raman, FTIR and DFT Zofia Dega-Szafran, Kinga Roszak, Andrzej Katrusiak, Anna Komasa, Mirosław Szafran Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznań, Poland
Corresponding author E mail address: [email protected] (Z.Dega-Szafran)
Graphical abstract Hydrogen-bonded piperidine-ethanol with p-hydroxybenzoic acid hydrate. X-Ray, Raman, FTIR and DFT studies Z. Dega-Szafran, K. Roszak, A. Katrusiak, A. Komasa, M. Szafran
HIGHLIGHTS
Piperidine-ethanol, p-hydroxybenzoic acid and water forms a crystalline adduct.
The crystalline complex is studied by X-ray, IR, Raman methods.
Its structure is optimized by the B3LYP/6-311++G(d,p) approach.
Charges delocalization are analyzed using the NBO method.
ABSTRACT A novel and unique crystalline three-component complex was formed by 2-(1piperidine)ethanol, p-hydroxybenzoic acid and water at the ratio 1:1:1. Its structure has been determined by single-crystal X-ray diffraction. This is an example of a hydrogen-bonded interaction between amino alcohol and benzoic acid molecules. Water acts as a bridge between molecules. The molecules are linked through medium-strong OH···O hydrogen bonds from 2.665(6) to 2.813(6) Å and NH···O one of 2.744(5) Å in length. The molecular structure of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate has been characterized by FTIR and Raman spectra and optimized at the B3LYP/6-311++G(d,p) level of theory. The potential energy distributions (PED) have been used to assign the vibrational spectra. Charge delocalization was analyzed using the natural bond orbital (NBO) methods.
Keywords: 2-(1-Piperidine)ethanol; p-Hydroxybenzoic acid; Hydrogen bonds; X-ray diffraction; Raman and FTIR spectra; DFT calculations. 1. Introduction
Aminoalcohols are an important class of organic compounds containing both amine and a hydroxyl functional groups in one molecule. Hence they act as hydrogen bond donor and acceptor, and open a wide range of possible hydrogen interactions. Simple aminoalcohols are used as solvents, synthetic intermediates and high boiling-point bases [1]. 2-(1Piperidine)ethanol [N-(2-hydroxyethyl)piperidine], PEt, belongs to the amino alcohol family and is a widely used adsorbent for removing acid gases, such as H2S, COS and CO2, from gas streams [2], as a base quencher to determine the efficiency of the decomposition of photoacid generators [3] and as a catalyst for enantioselective synthesis [4]. PEt is a base characterized by the dissociation constant of 9.63 at 25 oC [5], a proton-acceptor in tris[oxalato(2-)silicateand tris[oxalato(2-)germanate] complexes [6] and it is hydrogen-bonded to non-metal pentaborate cation [7]. Amino alcohols are added to some medical drugs, e.g. diclofenac, in order to improve its solubility [8]. The acid-base properties of 2-(1-piperidine)ethanol play an important role in the interactions between some molecules. In the present work we have synthesized a new adduct formed between PEt and p-hydroxybenzoic acid, HBA. HBA has two different proton-donor groups, COOH (pKa1 = 4.48) and OH (pKa2 = 9.11) [9]. HBA crystallizes as a monohydrate, where a pair of HBA molecules is linked through the O-H···O hydrogen bonds of 2.678 Å between carboxyl groups, forming dimers held together by the hydrogen bonds between the phenolic hydroxyl group and water molecules of 2.595 and 2.823 Å [10]. Various methods have been proposed for preparation of esters of amine alcohols and benzoic or carboxylic acids [11-15]. It has been shown by varying the amino alcohol that the rate of the
esterification is heavily dependent on its ability to activate the carboxylic acid by intermolecular hydrogen bonding. Recently, we have studied the effect of a hydroxyl group in hydroxybenzoic acid as an additional proton-donor substituent on the structure of complexes of dipolar ions (zwitterions, betaines) [16-27]. However only two of these complexes investigated crystallize with a water molecule [24,25]. Trigonelline complexes with HBA are linked into a cyclic dimer through the two water molecules [24], while water molecules play the role of a bridge between the DABCO di-betaine (HBA)2 complexes [25]. The presently synthesized 1:1:1 crystalline complex of 2-(1-piperidine)ethanol with phydroxybenzoic acid and water (1) has been characterized by X-ray diffraction, Raman and FTIR spectroscopy. We have optimized its structure at the B3LYP/6-311++G(d,p) level of theory in order to understand the aggregation of this first example of the interaction between the amino ethanol and substituted benzoic acid.
2. Experimental 2.1. Synthesis 3.02 g of 2-(1-piperidine)ethanol dissolved in 1 mL methanol was added to a solution of 3.22 g of p-hydroxybenzoic acid in 6 mL of methanol. The reaction mixture was left for 10 days at room temperature. The solid product (6.2 g) was filtered off, washed with chloroform and acetonitrile. The crude product of the adduct of 1-(piperidine)ethanol with phydroxybenzoic acid (1) was recrystallized from methanol, m.p. 137 oC. It crystallizes with one water molecule. Analysis for (C14H21NO4)H2O, m.wt 285.33: calc. %C 58.93, %H 8.12, %N 4.91, found %C 59.24, %H 8.13, %N 4.92.
2.2. Measurements
Single crystal X-ray data of 1 were measured on a KUMA KM4-CCD diffractometer. The structure was solved by direct methods using SHELXS, and refined on F2 by full-matrix leastsquares with the SHELXL programs [28]. The positions of H-atoms were located from geometry (hydroxyl 0.82 Å, methylene 0.97 Å, arene 0.93 Å and 0.91 Å in the tertiary amine) and in the difference Fourier maps for H2O. The anisotropic thermal parameters were refined for the non-H-atoms, and isotropic Uiso parameters for H atoms were linked to Ueq of their carriers. The crystal data, together with the details concerning data collection and structure refinement are given in Table S1. The crystal data have been deposited in the Cambridge Crystallographic Database Centre as a Supplementary publication CCDC 1529735 and in the Crystallography Open Database, COD 3000097. Molecular illustrations were prepared using programs Mercury CSD 3.3 [29]. Crystal data: [C7H16NO]+ [C7H5O3]- H2O: M = 285.33; crystal system: monoclinic, space group: P21/c; a = 14.532(4) Å, b = 8.0118(14) Å, c = 14.157(4) Å, = 113.84(3)o; V = 1507.7(6) Å3; Z = 4, Dc = 1.257 g cm-3, Rint = 0.0803; R1[I>2I] = 0.0512, wR1[I>2I] = 0.1167 for 10604 unique reflections. FTIR spectra were measured in Nujol and Fluorolube suspensions between KBr plates using a Bruker IFS 66v/S instrument, with the resolution of 2 cm-1. Each spectrum was accumulated by acquisition of 64 scans. The FTIR spectrum presented was obtained with the use of the split mull technique, which combined the spectrum from two parts, that in the range of 4000-1326 cm-1 from the spectrum measured in Fluorolube and that in the range 1326-400 cm-1 from the spectrum measured in Nujol. The Raman spectrum of crystalline sample was measured on a Bruker FRA-106/S instrument operating at the 1064 nm exciting line of Nd:YAG laser with the resolution of 4 cm-1. The spectrum was accumulated by acquisition of 512 scans. Elemental analysis was made using an Elemental Model Vario EL III instrument.
2.3. Computational details The DFT calculations were performed with the GAUSSIAN 09 program package [30]. The calculations employed the B3LYP exchange-correlation functional, which combines the hybrid exchange functional of Becke [31,32] with the gradient-correlation functional of Lee et al. [33] and the split-valence polarized 6-311++G(d,p) basis set [34]. The X-ray geometry of 1 was used as a starting point for the calculations. All calculated IR frequencies are real and confirmed that the optimized structure corresponds to a minimum energy. The potential energy distribution (PED) of the vibrational modes of the optimized molecule 2 was determined using VEDA 4 program [35,36]. Only the PED greater than 10% were considered. The local group coordinates (Sn) and their descriptions are given in Table S2 in Supplementary material. The natural bond orbital (NBO) [37] calculations were performed using the Gaussian 09 package at the B3LYP/6-311++G(d,p) level of theory.
3. Results and Discussion 3.1. Synthesis The reaction between 2-(1-piperidine)ethanol (PEt) and p-hydroxybenzoic acid (HBA) was carried out at a room temperature and molecules were not undergo the reaction of esterification, as it was shown in earlier studies [11-15]. PEt, forms a stable crystalline complex with HBA, and water at the 1:1:1 ratio (1).
3.2. Crystal structure The crystals of complex 1 are monoclinic of space group P21/c. Labeling of atoms is shown in Fig. 1. The bond lengths, bond and torsion angles are listed in Table S3. HBA transfers the proton from the carboxylic group to the nitrogen atom of the 2-(1-
piperidine)ethanol moiety, while the hydroxyl group of the ethanol moiety interacts with the second oxygen atom of the carboxylate group of HBA, and the PEtH+ cation is linked to the HBA- anion through the N(1)-H(1)∙∙∙O(3) and O(1)-H(O1)∙∙∙O(2) hydrogen bonds of 2.744(5) and 2.665(6) Å, respectively. The C(17)-O(2) and C(17)-O(3) bond lengths of the carboxylate group of HBA equal 1.266(1) and 1.278(1) Å confirm the presence of p-hydroxybenzoate in the crystal structure. Both carboxylate hydrogen atoms are double proton-acceptor to O(1)H and H2O, and to N(1)H and O(4)H, respectively (Table 1). The water molecule acts as a double proton-donor and links two PEt∙HBA complexes through O(1)∙∙∙H(W1)-O(W)H(W2)∙∙∙O(2) hydrogen bonds of 2.811(6) and 2.813(6) Å, respectively (Fig. 1, Table 1). The phenolic hydroxyl group O(4)-H(4) interacts with the O(3) oxygen atom of the carboxylate group of HBA of the neighboring complexes through the O(4)-H(O4)∙∙∙O(3) hydrogen bond of 2.693(6) Å and links the molecules into eight-membered cyclic aggregate described by the graph set R88(32) (Fig. 1) [38]. The independent unit of the PEt·HBA·H2O complex is asymmetric, whereas the whole crystal structure is centrosymmetric. The OH∙∙∙O and NH∙∙∙O hydrogen bonds form a 3-dimensional network (Fig. 2). The piperidine ring has a chair conformation with the CH2CH2OH group in an equatorial position.
3.2. Optimized structure
The structure of 2 is optimized at the B3LYP/6-311++G(d,p) level of theory and it is shown in Fig. 3. The geometrical parameters listed in Table S3 reproduce very well the crystal structure of 1. The calculated mean absolute difference (MAD) between the experimental and calculated bond lengths is 0.014 Å and bond angles is 0.81o. The main differences between 1 and 2 are observed in the torsion angles, especially in the carboxylate group of the HBA moiety and the plane of the aromatic ring (Table S3). The B3LYP functional has been
previously used as an efficient method for calculation of molecular structures and charge transfer properties [39-42]. Similarly as in 1, the 2-(1-piperidinium)ethanol action is joined to p-hydroxybenzoate anion though N-H∙∙∙O(3) and O(1)-H∙∙∙O(2) hydrogen bonds of 2.613 and 2.742 Å, respectively. However, the N∙∙∙O(3) distance in 2 is by 0.131 Å shorter than in 1, while the O(1)∙∙∙O(2) is longer by 0.077 Å (Table 1). The calculated energy for 2 is E(HF) = 978.549648 a.u. and dipole moment is = 5.36 D. The natural bond orbital (NBO) analysis has been proved to be an effective tool for chemical interpretation of electron density. It provide information about the interactions between electron-donors and electron-acceptors. It is also an efficient method for studying intra- and intermolecular bonding and interaction between bonds [37,43-46]. Table 2 summarizes the natural atomic charges of atoms in 2 and in pure 1-(2-piperidine)ethanol and p-hydroxybenzoic acid. Labeling of atoms is shown in Fig. 3. The protonation on N(1) reduces the decreasing the net charge in comparison to pure PEt, while the charge on O(1), engaged in the OH∙∙∙O hydrogen bond becomes more negative in complex 2 than in PEt. The charge on H(O1) is more positive in 2 than that on PEt. The charges on the oxygen atoms of the COOH and COO- groups in HBA and 2 are compared with the charges on atoms in HBA. The charges on O(2) and O(3) atoms are more negative in HBA moiety of 2 than in pure HBA.
3.3. Vibrational spectra
The experimental Raman and FTIR spectra of 2-(1-piperidinium)ethanol phydroxybenzoate hydrate, 1, and the theoretical IR spectrum of the isolated molecule 2, calculated at the B3LYP/6-311++G(d,p) level of theory and scaled by the factor of 0.9679
[47] are shown in Fig. 4. The wavenumbers of the experimental (ν̃exp), calculated (ν̃cal) and scaled (ν̃scal) bands are listed in Table S4. Generally, theoretical calculations overestimate the magnitudes of vibrational frequencies. The computed bands are shifted to higher wavenumbers relative to the experimental data, because the calculations are based on the harmonic frequency, while the experimental ones are based on the anharmonic frequencies. The difference follows also from the fact, that the experimental spectrum is recorded for compound 1 in the solid state, while the computations are made for vibrations of an isolated molecule 2. The distribution of the vibrational energy in internal coordinates (PED), defined and recommended by Keresztury and Jalsovszky [48], was used to assign vibrational bands in 2. According to the crystal structure there are four OH∙∙∙O hydrogen bonds of moderate strengths and one NH∙∙∙O hydrogen bond, in which both the ethanol OH, phenolic OH, water OH, carboxylate COO groups and piperidinium N+H atom are engaged (Fig. 1, Table 1). As a consequence, the OH and NH modes of the groups involved in the hydrogen bonds appear as a broad absorption in the 3400-2000 cm-1 region with submaxima at 3120, 2854, 2800, 2670, 2540 and 2320 cm-1, and they are difficult to separation. The shape of bands are probably due to an anharmonic coupling of the stretching AH with the stretching (AHB) vibrations, A – acid, B – base [49]. In the FTIR spectrum of 1 (Fig. 4b) the bands at 3524 and 3456 cm-1 are attributed to the asO(W)H(W) and sO(W)H(W) vibrations in the water molecule, respectively. In the Raman spectrum (Fig. 4a) no such absorption is observed. However, in the computed IR spectrum of 2 (Fig. 4d) the bands at 3766 and 3709 cm-1 are predicted to corresponds to O(W)H(W) and O(4)H(O4), respectively. The PED corresponding to these vibrations reveal pure OH stretching modes. In the calculated IR spectrum the bands at 3378 and 3321 cm-1 are predicted to be assigned to the O(1)H hydrogen bonding to the carboxylate group of HBA and to water molecule. The bands at 1598
and 692 cm-1 are predicted to O(W)H and O(W)H, and observed at 1629 and 705 cm-1, respectively. The strong band at 1387 cm-1 in the experimental spectrum of 1 is attributed to the O(1)H vibration and computed at 1421 and 1382 cm-1, while the O(4)H mode is predicted at 1152 cm-1 and observed at 1157 cm-1. Their contribution according to PED are found to be 64, 18 and 56 %, however all frequencies have PED values mixed with the other modes. In the theoretical spectrum of 2 the most intensive band at 2196 cm-1 corresponds only to the NH∙∙∙O(3) mode, the PED value is found to be 91%, while the band at 1563 cm-1 is assign to the NH vibration and that at 1524 cm-1 to the NH mode. In the experimental spectra the bands at 1553 cm-1 (Raman) and 1551 cm-1 (FTIR) are attributed to the NH vibration. The broad absorption in the 3400-2000 cm-1 region overlaps the CH and CH2 vibrations. They are visible in the Raman spectrum (Fig. 4a) in the range of 3200-2800 cm-1 and in the second derivative spectrum, d2 (Fig. 4c). In the latter spectrum, d2, the minima have the same wavenumbers as the maxima in the absorbance spectrum, but their relative intensities vary inversely with the square of the half-width of the absorbance bands, hence the broad bands due to OH∙∙∙O and NH∙∙∙O in the FTIR spectrum are not observed in the d2 spectrum [50,51]. The d2 spectrum proves that the broad absorption in the range of 3400-2000 cm-1 is attributed to OH and NH vibrations of the atoms engaged in the hydrogen bonds. Theoretically, the stretching CH modes of the phenyl ring are predicted in the higher wavenumbers region (3100-3046 cm -1) than the CH2 modes of the hetero-alicyclic ring and ethyl unit (3030-2908 cm-1). Some of them are visible in the extended d2 spectrum (Fig. 4c). The intensive bands at 1603 cm-1 (Raman) and 1599 cm-1 (FTIR) are assigned to the CC vibrations in the aromatic ring. Theoretically, the CC vibrations are predicted at 1593, 1583, 1563, 1490 and 1485 cm-1. In the IR spectrum of sodium p-hydroxybenzoate the band at 1590 cm-1 has been assigned to the CC vibration [44], while the bands at 1547 and 1416 cm-1 to
the asCOO and sCOO vibrations [52]. In the FTIR spectrum of 1 the asCOO vibrations at 1474 and 1367 cm-1 are observed. The presence of two asCOO bands can be explained of two different engagement in H-bonds of the carboxylate oxygen atoms, O(2) with the water molecule and the hydroxyl group of ethanol moiety, and O(3) with nitrogen atom of piperidinium units. The computed wavenumbers corresponding to the asCOO vibrations are predicted at 1485 and 1363 cm-1, however these modes are also mixed with the contributions of NH, H2O and CH2. The selected experimental and computed frequencies for the crystal and optimized structures are listed in Table S4. The mean absolute difference, MAD = calc(scaled) - exp/n) calculated for all scal frequencies is 11, while for selected ones (without without OH∙∙∙O, NH∙∙∙O and OH) is 4.
4. Conclusions
2-(1-Piperidine)ethanol, PEt, forms a crystalline hydrogen-bonded ionic pair complex with p-hydroxybenzoic acid, HBA. The water molecule acts as a bridge between complexes. This is the first example of interaction between aminoalcohol and benzoic acid molecules. The structure optimized at the B3LYP/6-311++G(d,p) level of theory reproduces well the aggregate form in the crystal. The solid state FTIR spectrum shows a broad absorption in the 3400-2000 cm-1 attributed to the stretching vibrations of OH···O and NH···O bands. The NBO analysis shows differences between the hydrogen-bonded PEt and HBA molecules, and these in pure components.
Acknowledgements The computations were performed at the Poznań Supercomputing and Networking Center and supported in part by PL-Grid Infrastructure.
References [ 1] M. Frauenkron, J.-P. Melder, G. Ruider, R. Rossbacher, H. Höke, Ethanolamines and propanolamines in Ullmans Encyclopedia of Industrial Chemistry, 2002, Wiley-VCH, Weinheim, doi:10.1002/14356007 a10_001. [ 2] K. Tomizaki, S. Shimizu, M. Onoda, Y. Fujioka, Chem. Lett. 37 (2008) 516-517. [ 3] A.R. Pawloski, Ch. Nealey, P.F. Nealey, Chem. Mater. 13 (2001) 4154-4162. [ 4] F. Lutz, T. Igarashi, T. Kawasaki, K. Soai, J. Am. Chem. Soc. 127 (2005) 12206-12207. [ 5] S. Xu, F.D. Otto, A.E. Mather, Can. J. Chem. 71 (1993) 1048-1050. [ 6] O. Seiler, C. Burschka, M. Penka, R. Tacke, Z. Anorg. Allg. Chem. 628 (2002) 24272434. [ 7] M.A. Beckett, P.N. Horton, M.B. Hursthouse, D.A. Knox, J.L. Timmis, Dalton Trans. 39 (2010) 3944-3951. [ 8] C. Castelano, P. Sabatino, Acta Crystallogr. C 52 (1996) 1708-1712. [ 9] J. Hermans, S.J. Leach, H.A. Scheraga, J. Am. Chem. Soc. 85 (1963) 1390-1395. [ 10] K. Fukuyama, K. Ohkura, S. Kashino, M. Haisa, Bull. Chem. Soc. Jpn. 46 (1973) 804808. [ 11] W.G. Christiansen, S.E. Harris, United States Patent 2,243,694 (1941). [ 12] T.E. Jones, C.O. Wilson, J. Pharm. Sci. 42 (1953) 340-341. [ 13] T.E. Jones, C.O. Wilson, J. Pharm. Sci. 42 (1953) 342-343. [ 14] M. Robin, S.R. Schulte, United States Patent 3,758,547 (1973). [ 15] S. Breitenlechner, T. Bach, Z. Naturforsch. 61b (2006) 583-588. [ 16] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Przedwojska, M. Szafran, J. Mol. Struct. 649 (2003) 257-268. [ 17] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct.785 (2006) 160-166. [ 18] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 797 (2006) 82-91. [ 19] Z. Dega-Szafran, M. Jaskólski, M. Szafran, Pol. J. Chem. 81 (2007) 931-946. [ 20] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 844-845 (2007) 38-47. [ 21] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 875 (2008) 346-353. [ 22] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 923 (2009) 72-77.
[ 23] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 967 (2010) 80-88. [ 24] Z. Dega-Szafran, G. Dutkiewicz, Z. Kosturkiewicz, M. Szafran, J. Mol. Struct. 985 (2011) 219-226. [ 25] P. Barczyński, Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 994 (2011) 131-136. [ 26] Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 994 (2011) 144-149. [ 27] P. Barczyński, Z. Dega-Szafran, A. Katrusiak, M. Szafran, J. Mol. Struct. 1000 (2011) 127-134. [ 28] G.M. Sheldrick (2008) Acta Crystallogr A 64 (2008) 112-122. [ 29] C.F. Macrae, P.R. Edgington, P. McCabe, E. Pidcock, G.P. Shields, R. Taylor, M. Towler, J. van de Streek, J. Appl. Crystallogr 39 (2006) 453-457. [ 30] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery, Jr., J.E. Peralta, F. Ogliaro, M. Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth, P. Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, O. Farkas, J.B. Foresman, J.V. Ortiz, J. Cioslowski, D.J. Fox, GAUSSIAN 09, Revision B.01, Gaussian, Inc., Wallingford CT, 2010. [ 31] A.D. Becke, J. Chem. Phys. 98 (1993) 5648-5652. [ 32] A.D. Becke, J. Chem. Phys. 107 (1997) 8554-8560. [ 33] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785-789. [ 34] W.J. Hehre, L. Radom, P.V.R. Schleyer, J.A. Pople, Ab Initio Molecular Orbital Theory, Wiley, New York, 1986. [ 35] M.H. Jamróz, Vibrational Energy Distribution Analysis; VEDA 4 Program, Warsaw, Poland, 2004-2010, http://smmg.pl. [ 36] M.H. Jamróz, Spectrochim. Acta A 114 (2013) 220-230. [ 37] A.E. Reed, L.A. Curtiss, F. Weinhold, Chem. Rev. 88 (1988) 899-926. [ 38] M.C. Etter, J.C. MacDonald, J. Bernstein, Acta Crystallogr. B 46 (1990) 256-262.
[ 39] A. Irfan, A.R. Chaudhry, A. G. Al.-Sehemi, M.S. Al.-Asiri, S. Muhammad, A. Kalam, J. Saudi Chem Soc. 20 (2016) 336-342. [ 40] A. Irfan, A. G. Al.-Sehemi, A.R. Chaudhry, S. Muhammad, M.S. Al.-Asiri, Optik 127 (2016) 10148-10157. [ 41] A. Irfan, A. Kalam, A.R. Chaudhry, A. G. Al.-Sehemi, S. Muhammad, Optik 132 (2017) 101-110. [ 42] A. Irfan, A. G. Al.-Sehemi, A.R. Chaudhry, S. Muhammad, Optik 138 (2017) 349-358. [ 43] A.E. Reed, F. Weinhold, J. Chem Phys. 78 (1983) 4066-4073. [ 44] S. Snehalatha, C. Ravikumar, I. Hubert Joe, N. Sekar, V.S. Jayakumar, Spectrochim. Acta A 72 (2009) 654-662. [ 45] D.M. Suresh, A. Amalanathan, S. Sebastian, D. Sajan, I. Hubert Joe, V. Bena Jothy, I. Nemec, Spectrochim. Acta A 115 (2013) 595-602. [ 46] R.P. Gangadharan, S. Sampath Krishnan, Acta Physica Polonica A, 125 (2014) 18-22. [ 47] M.P. Andersson, P. Uvdal, J. Phys. Chem. 109 (2005) 2937-2941. [ 48] G. Keresztury, G. Jalsovszky, J. Mol. Struct. 10 (1971) 304-305. [ 49] S. Bratos, H. Ratajczak, P. Viot in C.J. Dore, J. Teiseire (eds) Hydrogen Bond Liquids, Kluwer, Academic Press, 1991. [ 50] W.F. Maddams, M.J. Southon, Spectrochim. Acta A 38 (1992) 459-466. [ 51] G. Talsky, Derivative Spectrophotometry, VCH, Weinheim, 1994. [ 52] G.E. Dunn, R.S. McDonald, Can. J. Chem. 47 (1969) 4577-4588.
FIGURE CAPTIONS Fig. 1. Hydrogen bond interactions in an eigth-membered cyclic aggregate of 2-(1piperidinium)ethanol p-hydroxybenzoate hydrate (PEt∙HBA∙H2O) R88(32). Hydrogen bonds have been marked by dotted lines. The symmetry-independent atoms of one PEt∙HBA∙H2O unit, as well as some H-bond connections, have been labeled. Fig. 2. Crystal packing of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 1, viewed down [010]. H-atoms have been skipped for clarity. Fig. 3. The molecular structure of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 2, optimized by the B3LYP/6-311++G(d,p) approach. Hydrogen bonds have been marked by dotted lines. Fig. 4. The spectra of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate (a) Raman, (b) FTIR, (c) the second derivative IR spectrum and (d) the IR spectrum calculated by the B3LYP/6-311++G(d,p) approach and all wavenumbers scaled by 0.9679.
Fig. 1. Hydrogen bond interactions in an eigth-membered cyclic aggregate of 2-(1piperidinium)ethanol p-hydroxybenzoate hydrate (PEt∙HBA∙H2O) R88(32). Hydrogen bonds have been marked by dotted lines. The symmetry-independent atoms of one PEt∙HBA∙H2O unit, as well as some H-bond connections.have been labeled.
Fig. 2. Crystal packing of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 1, viewed down [010]. H-atoms have been skipped for clarity.
Fig. 3. The molecular structure of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate, 2, optimized by the B3LYP/6-311++G(d,p) approach. Hydrogen bonds have been marked by dotted lines.
3500 3000 2500 2000
1800
1600
1400
1200
1000
800
600
424
608
746
1233
623
869
1357
513 438
709
799
914
991
1077
1167
1271
2800
1151 1065
1235
1363
2900 1631 1600 1553 1507 1453
2859
2942
2955
3013
3048
3079
Absorbance 2nd deriv.
779
513 439
705
1009 991 949
1387
1599
624
1272 1234 1166 1079
1550
868 798
1508 1453
1629
3120 2854 2800 2670 2540 2320
3524 3456
Absorbance
(b)
1485
(d) 2196
3000
1583
3321
3378
3100
2942
3766 3709
Absorbance
524
1145
639
764
867
1081 1031
1274
2960
1553 1515 1440
3063
Raman activity
1387
1603
(a)
(c)
-1
400
Wavenumbers (cm )
Fig. 4. The spectra of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate (a) Raman, (b) FTIR (c) the second derivative IR and (d) the IR spectrum calculated by the B3LYP/6311++G(d,p) approach and all wavenumbers scaled by 0.9679.
Table 1. Experimental and calculated by the B3LYP/6-311++G(d,p) approach hydrogen-bonds dimensions (Å,°) in the complex of 2-(1-piperidinium)ethanol p-hydroxybenzoate hydrate.
X-ray 1
B3LYP 2
D–H···A
DH
H···A
D···A
DHA
O(1)H(O1)∙∙∙O(2) O(W)H(W1)∙∙∙O(1)a O(4)H(O4)∙∙∙O(3)b O(W)H(W2)∙∙∙O(2) N(1)H(1)∙∙∙O(3)
0.820 0.820 0.820 0.820 0.910
1.845 2.024(9) 1.875 2.095(5) 1.859
2.665(6) 2.811(6) 2.693(6) 2.813(6) 2.744(5)
179.26 159.62 176.67 146.00 163.49
O(1)H(O1)∙∙∙O(2) N(1)H(1)∙∙∙O(3) O(W)H(W2)∙∙∙O(2)
0.982 1.096 0.982
1.763 1.536 1.774
2.742 2.613 2.744
174.09 166.03 168.81
Symmetry codes: a x, 1+y, z; b x, 1.5y, 0.5+z.
Table 2. Selected natural atomic charges (NBO) (e) for atoms in the complex of 2-(1piperidine)ethanol with p-hydroxybenzoic acid (2), 2-(1-piperidine)ethanol (PEt), and phydroxybenzoic acid (HBA). Atoma N(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) O(1) H(O1) H(1) a
2 -0.5328 -0.1558 -0.4079 -0.3812 -0.4028 -0.1775 -0.1833 -0.0521 -0.7644 0.4985 0.4774
PEt -0.6001 -0.1625 -0.3886 -0.3812 -0.3883 -0.1698 -0.1943 -0.0280 -0.7399 0.4653 -
Labels of atom in Fig. 3.
Atoma C(11) C(12) C(13) C(14) C(15) C(16) C(17) O(2) O(3) O(4) H(O3) H(O4)
2 -0.1765 -0.1409 -0.2902 0.3475 -0.2600 -0.1435 0.8113 -0.8037 -0.7752 -0.6723 0.4663
HBA -0.1996 -0.1284 -0.2847 0.3414 -0.2537 -0.1376 0.7881 -0.6089 -0.6938 -0.6622 0.4850 0.4699