Non-covalent interactions in organic-inorganic hybrid compounds derived from amino amides

Journal of Molecular Structure 1202 (2020) 127258

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Non-covalent interactions in organic-inorganic hybrid compounds derived from amino amides
n Avila-Montiel a, Antonio Rafael Tapia-Benavides a, Eltonh Islas-Trejo a, Concepcio Armando Ariza b, Hugo Tlahuext c, **, Margarita Tlahuextl a, *

noma del Estado de Hidalgo, Carr. Pachuca-Tulancingo km 4.5, Hidalgo, CP 42184, Mexico Area Acad
emica de Química, Universidad Auto Departamento de Química, CINVESTAV-IPN, Av. IPN 2508, Ciudad de M
exico, CP 07360, Mexico c
noma del Estado de Morelos, Av. Universidad 1001, Morelos, CP 62209, Mexico Centro de Investigaciones Químicas, Universidad Auto a

b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 21 August 2019 Received in revised form 15 October 2019 Accepted 18 October 2019 Available online 21 October 2019

Here, we report the synthesis of six organic-inorganic hybrid compounds from amino amides and tetrachlorozincate anions to study the processes underlying the modulation of hydrogen bonds and p∙∙∙p interactions in these salts. Thus, 2-((2-ammoniopropanamido)-methyl)-1H-benzimidazole-3-ium tetrachlorozincate 7, 2-(1-(2-ammoniopropanamido)-ethyl)-1H-benzimidazole-3-ium tetrachlorozincate 8, 2-((2-ammonio-3-methylbutanamido)methyl)-1H-benzimidazole-3-ium tetrachlorozincate 9, 2-(1-(2ammonio-3-methylbutanamido)-2-methylpropyl)-1H-benzimidazole-3-ium tetrachlorozincate 10, 2((2-ammonio-4-methylpentanamido)methyl)-1H-benzimidazole-3-ium tetrachlorozincate 11, and 2-(1(2-ammonio-4-methylpentanamido)-3-methylbutyl)-1H-benzimidazoel-3-ium tetrachlorozincate 12 were obtained from the corresponding hydrochlorides (1e6). Crystallographic experiments using compounds 7e12 revealed that the presence of bulky substituents situated on C10 and C13 reduces the efficacy of stacking phenomena. Moreover, the ZnCl2
4 ∙∙∙HeN hydrogen bonds induce the polarization of the imidazole ring and the p∙∙∙p interactions occur through the “dipole-induced dipole” mechanism. In the case of NeH∙∙∙solvent interactions, the stacking phenomena occur preferentially through the “induced dipole-induced dipole” mechanism. © 2019 Elsevier B.V. All rights reserved.

Keywords: Organic-inorganic hybrid p-stacking Hydrogen bond Amino amide Tetrachlorozincate

1. Introduction Non-covalent interactions play essential roles in chemical, physical and biological systems [1e8]. These weak interactions exert cooperative effects on many macromolecular systems, and therefore are useful in crystal engineering, drug designing, molecular recognition, catalysis, and self-assembly [9e15]. Among these interactions, the synergistic behavior of hydrogen bonds and p∙∙∙p interactions are critical in regulating the packing, assembly and conformational changes of DNA and proteins [16]. The p∙∙∙p interactions are favored in electron-poor aromatic systems. Thus, the existence of nitrogen atoms in the aromatic ring (or the presence of electron-withdrawing substituents) increases the possibility of face to face p stacking in these compounds [17].

* Corresponding author. ** Corresponding author. E-mail addresses: [email protected] (H. Tlahuext), [email protected] (M. Tlahuextl). https://doi.org/10.1016/j.molstruc.2019.127258 0022-2860/© 2019 Elsevier B.V. All rights reserved.

Moreover, pyridine, benzimidazole, and other aromatic nitrogen heterocycles are susceptible to coordinating metal ions or participating in hydrogen bond interactions. In these cases, the possibility of p stacking is enhanced and the supramolecular stabilization will be stimulated according to Hunter-Sanders rules [18e25]. The interplay between p stacking and the hydrogen bonding ability appears to be multifactorial. However, according to Mignon et al., a stacking molecule with a less rigid structure will have a larger capability for hydrogen bonding [26]. Thus, the charge transfer processes appear to be relevant to the modulation of these non-covalent interactions [27]. In this context, we hypothesize that the presence of p∙∙∙p interactions in ammonium cations is possible when weak anion-cation interactions are present. Likewise, our studies about protonated amino amides showed that anion-cation interactions depend on the geometry and size of the
anion. For example, ZnCl2
4 is larger than the Cl anion and therefore, hydrogen bonding through charge transfer is a disadvantage in tetrachlorizincate [28]. Thus, the hard-soft nature of anions is a potentially relevant factor promoting p stacking in aromatic

2

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

ammonium cations. We studied the weak interactions of ZnCl2
4 with cations derived from amino amides 7e12 (Scheme 1) because these compounds are capable of forming stable supramolecular structures. Tetrachlorozincate ions may participate in weaker interactions with NeH systems than other anions (as Cl
or NO
3 ) because they have two negative charges distributed in four chlorine atoms. Thus, we propose that the p∙∙∙p interactions in the supramolecular structure of amides derived from 2-(aminomethyl)benzimidazole (2AMBZ) and amino acids would be maximized in the presence of ZnCl2
4 . Moreover, the p∙∙∙p interactions in these compounds were modulated by different substituents in the C10 and C13 positions. In this study, we report the synthesis of new salts 8e12 and their interactions with ZnCl2
4 . Although compound 7 already was reported, we use this compound to contrast the supramolecular behavior of systems containing bulky substituents in the C10 and/ or C13 positions [28]. All compounds were characterized using multinuclear NMR, infrared, and mass spectrometry. Crystallography studies of salts 7e12 revealed how bulky substituents in amino amides determine the presence of p∙∙∙p interactions. Compounds 7e12 were synthesized from the corresponding hydrochlorides 1e6. 2. Experimental procedures 2.1. Materials and methods All reagents and solvents were purchased from Sigma-Aldrich or Merck and used without further purification. Hydrochlorides 1e6 were synthesized using published procedures [23]. All NMR spectra were recorded using a Bruker Advance instrument at 400 MHz. Chemical shifts are reported in ppm, with the residual solvent serving as the internal reference (DMSO‑d6, d ¼ 2.50 for 1H NMR and d ¼ 39.5 for 13C). All NMR spectra were recorded at 293 K. The pH of the medium was fixed using concentrated hydrochloric acid and was measured using a Corning pH meter 430. Mass spectra were recorded using an Agilent G1969 LC/MSD TOF spectrometer coupled to HPLC with electrospray ionization (compounds 7e11) and a JEOL MStation JMS-700 with FAB ionization (compound 12). The instruments were operated in positive mode as required. Melting points were determined using a Buchi Melting Point M-565 apparatus and were not corrected. Infrared spectra were recorded using a PerkinElmer System FT-IR/ FIR Frontier spectrometer in the range of 4000-370 cm
1. Raman spectra were measured using a PerkinElmer GX NIR FT-Raman

Spectrometer. Elemental analyses were performed using a PerkinElmer Series II CHNS/O analyzer 2400. 2.2. X-ray crystallography Structural and refinement parameters are presented in Table 1. All diffraction data were measured using a Xcalibur Atlas Gemini diffractometer with a charge-coupled device area detector and graphite-monochromated Mo Ka (l ¼ 0.7107 Å) radiation. The frames were collected at T ¼ 295 K via u/4-rotation at a rate of 10 s per frame. The measured intensities were corrected for absorption [empirical absorption correction using spherical harmonics, implemented with the SCALE3 ABSPACK scaling algorithm (CrysAlisPro, Agilent Technologies)] [29]. The diffraction data were solved using SHELXT and refined with full-matrix least-squares procedures using SHELXL within the OLEX-2 program package [30]. The non-hydrogen atoms were anisotropically refined. The CeH hydrogens were placed in geometrically calculated positions using a riding model with d(C-Haryl) ¼ 0.93 Å and Uiso(Haryl) ¼ 1.2 Ueq(C). The hydrogens that were bound to N and O atoms were localized by creating difference Fourier maps. The coordinates of the NeH and OeH hydrogens were refined using the following constraints: d(NeH) ¼ 0.89(1) Å, d(N-Himidazolic and amidic) ¼ 0.86(1) Å, d(OeH) ¼ 0.82(1) Å, and Uiso(H) ¼ 1.5 Ueq(N,O). The network contained one disordered water molecule in compound 11 (disordered water molecule (O3A and O3B) that was refined with occupancies of 0.50). The hydrogens of this water molecule were unable to be located in difference Fourier maps. In compounds 10 and 12, the chlorine atoms of tetrachlorozincate anion were disordered and refined with occupancies of 0.50. The crystallographic data for compounds 7e12 are summarized in the supplementary information. 2.3. Synthesis and characterization of compounds 7e12 Compounds 8e12 were synthesized using a similar procedure to salt 7. In all cases, the corresponding hydrochlorides 1e6 and ZnCl2 were used as reactive compounds. IR, Raman, and NMR spectra are shown in the supporting material. 2.4. 2-((2-Ammoniopropanamido)-methyl)-1H-benzimidazole-3ium tetrachlorozincate 7 A mixture of 116.8 mg (0.4 mmol) of 2-{[(2ammoniumpropanoyl)amino]methyl}-1H-benzimidazole-3-ium

Scheme 1. Salts 1e12.

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

3

Table 1 Selected crystallographic data for compounds 7e12. Identification code

7a

8

9

10

11

12

Empirical formula Formula weight Temperature/K Crystal system Space group a/Å b/Å c/Å a/  b/ g/ Volume/Å3 Z rcalc./g cm
3 m/mm
1 F(000) Radiation 2q range for data collection/o Index ranges

C11H16Cl4N4OZn 427.45 295 triclinic P
1 8.2337(4) 8.3178(4) 13.7957(8) 80.234(5) 82.890(4) 69.195(5) 868.34(8) 2 1.635 2.031 432 MoKa (l ¼ 0.71073) 5.914 to 49.998

C13H22Cl4N4O2Zn 473.51 295 monoclinic P 21/n 9.9168(2) 7.9154(2) 25.9549(7) 90 100.102(3) 90 2005.75(9) 4 1.568 1.771 968 MoKa (l ¼ 0.71073) 6.054 to 50

C26H42Cl8N8O3Zn2 929.01 295 triclinic P
1 11.2724(4) 12.9088(5) 15.3515(6) 108.276(3) 105.266(3) 96.328(3) 2000.49(14) 2 1.542 1.772 948 MoKa (l ¼ 0.71073) 5.89 to 51.996

C16H28Cl4N4O2Zn 515.59 295 triclinic P
1 7.6075(2) 10.3554(3) 15.1867(5) 82.679(2) 86.638(3) 76.935(2) 1155.38(6) 2 1.482 1.544 532 MoKa (l ¼ 0.71073) 6.054 to 51.994

C14H24Cl4N4O3Zn 503.54 295 monoclinic P 21/c 12.5269(5) 9.9255(3) 19.2584(9) 90 107.011(5) 90 2289.75(17) 4 1.461 1.559 1032 MoKa (l ¼ 0.71073) 6.036 to 49.998

C18H30Cl4N4OZn 525.63 295 triclinic P
1 10.5784(4) 11.4578(3) 11.6699(2) 91.0338(19) 96.465(2) 116.194(3) 1257.48(7) 2 1.388 1.417 544 MoKa (l ¼ 0.71073) 594 to 49.998


9  h  9,
9  k  9,
16  l  16 8356


11  h  11,
9  k  9,
30  k  30 72114


13  h  13,
15  k  15,
18  l  18 16303


9  h  9,
12  k  12,
18  l  18 56071


14  h  14,
11  k  11,
22  l  22 50596


12  h  12,
13  k  13, 13  l  13 66493

3029 [Rint ¼ 0.0534, Rsigma ¼ 0.0731] 3029/6/209

3537 [Rint ¼ 0.0361, Rsigma ¼ 0.0107] 3537/7/241

7850 [Rint ¼ 0.0222, Rsigma ¼ 0.0325] 7850/14/470

4533 [Rint ¼ 0.0413, Rsigma ¼ 0.0166] 4533/8/308

4018 [Rint ¼ 0.0304, Rsigma ¼ 0.0120]] 4018/8/271

4429 [Rint ¼ 0.0329, Rsigma ¼ 0.0113] 4429/6/284

1.024

1.102

1.012

1.083

1.084

1.132

R1 ¼ 0.0446, wR2 ¼ 0.0804 R1 ¼ 0.0897, wR2 ¼ 0.0943 0.043/-0.33

R1 ¼ 0.0265, wR2 ¼ 0.0628 R1 ¼ 0.0302, wR2 ¼ 0.0654 0.28/-0.20

R1 ¼ 0.0344, wR2 ¼ 0.0762 R1 ¼ 0.0496, wR2 ¼ 0.0840 0.91/-0.67

R1 ¼ 0.0345, wR2 ¼ 0.0888 R1 ¼ 0.0418, wR2 ¼ 0.0941 0.47/-0.37

R1 ¼ 0.0279, wR2 ¼ 0.0680 R1 ¼ 0.0352, wR2 ¼ 0.0739 0.46/-0.33

R1 ¼ 0.0467, wR2 ¼ 0.1436 R1 ¼ 0.0524, wR2 ¼ 0.1532 1.33/-0.42

1037088

1920510

1920511

1920513

1920514

1920515

Reflections collected Independent reflections Data/restraints/ parameters Goodness-of-fit on F [2] Final R indexes [I  2s(I)] Final R indexes [all data] Largest diff. peak/ hole/eÅ3 CCDC No. a

Ref 28.

dichloride 1 and 2 mL of de-ionized water were added to 2.0 mL of a solution 0.2 M ZnCl2 (0.4 mmol). The mixture was stirred for 5 min and then the pH was adjusted to 0.6 with concentrated hydrochloric acid. The resulting mixture was stirred at room temperature for 60 min. Next, the solvent was removed using an air stream, and the resulting colorless solid was washed with 2-propanol and recrystallized by slow evaporation with methanol. Compound 7 (yield: 132 mg, 69%). mp 220  C (decomposition). Found C, 29.35; H, 3.77; N, 12.18. Anal. calc. for C11H16N4OCl4Zn1.1H2O: C, 29.54; H, 4.10; N, 12.53%. (ATR) nmax/cm
1 3257 (NH), 2934 (CH), 2865 (CH), 1672 (CO), 1621 (CN), 1554 (NH), 1496 (NCN), 1407 (NH3), 1256 (CN). Raman (neat) nmax/cm
1 1562 (NH), 268 (ZnCl). dH (400 MHz, DMSO‑d6): d 9.43 (t, 1H, H11), 8.26 (br, 1H, H1,3), 7.76 (m, 2H, H5,6), 7.52 (m, 2H, H4,7), 4.81 (AB, 2H, H10), 4.03 (q, 2H, H13), 1.44 (d, 3H, H15). dC (100 MHz, DMSO‑d6): d 171.4 (C12), 151.7 (C2), 131.3 (C8,9), 126.6 (C5,6), 114.5 (C4,7), 49.0 (C13), 36.2 (C10), 17.2 (C15). TOF (m/z): calc. for [M-HZnCl4]þ: 219.1240, found: 219.1242. 2.5. 2-(1-(2-Ammoniopropanamido)-ethyl)-1H-benzimidazole-3ium tetrachlorozincate 8 (yield: 124 mg, 65%). mp 269  C. Found C, 29.17; H, 4.68; N, 11.04. Anal. calc. for C12H18N4OCl4Zn$[3H2O]: C, 29.09; H, 4.88; N, 11.31. (ATR) nmax/cm
1 3500 (NH), 3427 (OH), 3269 (NH), 2934 (CH), 1686 (CO), 1621 (CN), 1569 (NH), 1482 (NCN), 1393 (NH3), 1371 (NH), 1257 (CN), 760 (CH). Raman (neat) nmax/cm
1, 1556 (NH), 270 (ZnCl). dH (400 MHz, DMSO‑d6): d 9.48 (d, 1H, H11), 8.27 (br, 1H, H1), 7.78 (m,

2H, H4,7), 7.53 (m, 2H, H5,6), 5.34 (q, 1H, H10), 4.00 (t, 1H, H13), 1.68 (d, 3H, H16), 1.42 (d, 3H, H15). dC (100 MHz, DMSO‑d6): d 170.1 (C12), 154.6 (C2), 131.1 (C8,9), 125.8 (C5,6), 114.1 (C4,7), 48.5 (C13), 43.0 (C10), 18.3 (C16), 16.6 (C15). TOF (m/z): calc. for [M-HZnCl4]þ: 233.139687, found: 233.139981. 2.6. 2-((2-Ammonio-3-methylbutanamido)methyl)-1Hbenzimidazole-3-ium tetrachlorozincate 9 (yield: 132 mg, 69%). mp > 287  C. Found C, 33.29; H, 4.56; N, 11.52. Anal. calc. for C13H20N4OCl4Zn$[H2O]: C, 32.98; H, 4.68; N, 11.83. (ATR) nmax/cm
1 3514 (OH), 3260 (NH), 3064 (CH), 2938 (CH), 1670 (CO), 1626 (CN), 1538 (NH), 1498 (NCN), 1396 (NH3), 1296 (CN), 752 (CH), Raman (neat) nmax/cm
1 1564 (NH), 275 (ZnCl). dH (400 MHz, DMSO‑d6): d 9.52 (d, 1H, H11), 8.35 (br, 1H, H1), 7.78 (m, 2H, H4,7), 7.50 (m, 2H, H5,6), 4.84 (AB, H10), 3.72 (d, 1H, H13), 2.14 (m, 1H, H15), 0.95 (d, 3H, H17), 0.94 (d, 3H, H16). dC (100 MHz, DMSO‑d6): d 169.5 (C12), 151.3 (C2), 131.4 (C8,9), 125.6 (C5,6), 114.1 (C4,7), 57.9 (C13), 35.7 (C10), 29.5 (C15), 18.5 (C16), 17.9 (C17). TOF (m/z): calc. for [M-HZnCl4]þ: 247.155337, found: 247.155572. 2.7. 2-(1-(2-Ammonio-3-methylbutanamido)-2-methylpropyl)1H-benzimidazole-3-ium tetrachlorozincate 10 (yield: 146 mg, 71%). mp 291  C. Found C, 36.93; H, 5.68; N, 10.66. Anal. calc. for C16H26N4OCl4Zn[1.3H2O]: C, 36.89; H, 5.53; N, 10.75. (ATR) nmax/cm
1, 3500 (OH), 3282 (NH), 3128 (NH), 3040

4

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

1H, H1), 7.78 (m, 2H, H4,7), 7.51 (m, 2H, H5,6), 5.31 (m, 1H, H10), 3.93 (m, 1H, H13), 1.93 (m, 3H, H15), 1.88 (m, 1H, H20), 1.63 (m, 2H, H16,19), 0.97 (d, 3H, H22), 0.95 (d, 3H, H18), 0.93 (d, 3H, H17), 0.92 (d, 3H, H21). dC (100 MHz, DMSO‑d6): d 170.0 (C12), 154.1 (C2), 131.7 (C8,9), 125.7 (C5,6), 114.2 (C4,7), 51.1 (C13), 45.5 (C10), 39.8 (C19), 24.3 (C20), 23.7 (C16), 22.8 (C22), 22.7 (C18), 21.8 (C17), 20.8 (C21). FAB (m/z): calc. for [M-HZnCl4]þ: 317.23, found 317.

(CH), 2970 (CH), 2921 (CH2), 1699 (CO), 1626 (CN), 1532 (NH), 1489 (NCN), 1372 (NH3), 1261 (CN), 763 (CH). Raman (neat) nmax/cm
1 1556 (NH), 279 (ZnCl). dH (400 MHz, DMSO‑d6): d 9.42 (d, 3J ¼ Hz, 1H, H11), 8.49 (br, 1H, H1), 7.81 (m, 2H, H4,7), 7.55 (m, 2H, H5,6), 5.26 (t, 1H, H10), 3.93 (q, 1H, H13), 2.61 (m, 1H, H18), 2.12 (m, 1H, H15), 1.02 (d, 3H, H17), 1.00 (d, 3H, H16), 0.98 (d, 3H, H19), 0.965 (d, 3H, H20), 0.95 (d, 3H, H17), 0.94 (d, 3H, H16). dC (100 MHz, DMSO‑d6): d 169.6 (C12), 152.9 (C2), 131.0 (C8,9), 125.8 (C5,6), 114.1 (C4,7), 57.6 (C13), 52.7 (C10), 30.6 (C18), 29.4 (C15), 18.9 (C19), 18.3 (C17,20), 17.4 (C16). TOF (m/ z): calc. for [M-HZnCl4]þ: 289.202288, found: 289.202373.

3. Results and discussion 3.1. Synthesis and characterization of tetrachlorozincates 7e12

2.8. 2-((2-Ammonio-4-methypentanamido)methyl)-1Hbenzimidazole-3-ium tetrachlorozincate 11

Tetrachlorozincate salts 7e12 were obtained from the reaction of amino amide hydrochlorides 1e6 with ZnCl2 at a pH less than 1.0. These compounds are soluble in protic solvents, and therefore they were crystallized in 2-propanol and/or methanol (Fig. S1 in the supporting material). Thus, compounds 7, 9, 10, and 12 crystallized in centrosymmetric group P-1, for compound 8 crystallized in centrosymmetric group P21/n and compound 11 crystallized in centrosymmetric group P21/c (Table 1). A potential explanation for this result is that the crystal cell of these salts is composed of racemates. Moreover, compounds 8e11 crystallized in solvated forms, [C12H18Cl4N4OZn]$CH3OH, [C13H20Cl4N4OZn]$H2O, [C16H26Cl4N4OZn]$H2O, and [C14H22Cl4N4OZn]$2H2O, respectively. In these cases, water (compound 9e11) or methanol (compound 8) participate in the hydrogen bond interactions in the supramolecular structure. Crystallographic studies revealed similar structural features for the amino amides in compounds 7e12. However, the C]O bond length in compound 10 [the compound with isopropyl substituents at the C10 and C13 positions] is shorter than in the other salts (Table 2). This reduction in the bond length is attributed to the lack of hydrogen bond interactions with the carbonyl group in compound 10. Thus, the molecular conformation assumed by the organic fragment and the existence of the isopropyl substituent at

176  C.

Found C, 33.62; H, 5.45; N, 10.66. (yield: 86 mg, 86%). mp Anal. calc. for C14H22N4OCl4Zn$[2H2O]: C, 33.26; H, 5.18; N, 11.08. (ATR) nmax/cm
1 3420 (OH), 3211 (NH), 3066 (CH), 2960 (CH2), 1684 (CO), 1621 (CN), 1500 (NCN), 1370 (NH), 1248 (CN), 760 (CH). Raman (neat) nmax/cm
1 1565 (NH), 278 (ZnCl). dH (400 MHz, DMSO‑d6): d 9.65 (t, 1H, H11), 8.40 (br, 1H, H1), 7.80 (m, 2H, H4,7), 7.53 (m, 2H, H5,6), 4.84 (t, 2H, H10), 3.93 (q, 1H, H13), 1.65 (m, H, H15), 1.59 (m, 2H, H16), 0.92 (d, 3H, H17), 0.91 (d, 3H, H16). dC (100 MHz, DMSO‑d6): d 170.4 (C12), 151.3 (C2), 131.3 (C8,9), 125.7 (C5,6), 114.1 (C4,7), 51.1 (C13), 39.9 (C15), 35.8 (C10), 23.7 (C16), 22.6 (C18), 22.0 (C17). TOF (m/ z): calc. for [M-HZnCl4]þ: 261.170987, found: 261.171244. 2.9. 2-(1-(2-Ammonio-4-methylpentanamido)-3-methylbutyl)-1Hbenzimidazole-3-ium tetrachlorozincate 12 (yield: 28 mg, 26%). mp 270  C. Found C, 41.34; H, 6.37; N, 10.16. Anal. calc. for C18H30N4OCl4Zn[0.7CH3OH]: C, 40.98; H, 6.03; N, 10.22. (ATR) nmax/cm
1 3231 (NH), 3057 (CH), 2958 (CH), 2876 (CH2), 1702 (CO), 1628 (CN), 1545 (NH), 1490 (NCN), 1370 (NH3), 1238 (CN), 759 (NH). Raman (neat) nmax/cm
1 1562 (NH), 281 (ZnCl). dH (400 MHz, DMSO‑d6): d 9.59 (d, 3J ¼ Hz, 1H, H11), 8.40 (br, Table 2 Selected bond lengths, angles and dihedral angles of compounds 7e12. 7a

8

9

10

11

12

Bond lengths (Å) N1eC2

1.321(5)

1.327(3)

1.322(3)

1.320(3)

1.316(4)

N3eC2

1.328(5)

1.326(3)

1.390(3)

1.327(3)

1.324(4)

N11eC12

1.329(5)

1.334(3)

1.341(3)

1.325(3)

1.337(4)

C12eO1

1.222(5)

1.226(3)

1.327(3) 1.322(4) 1.387(4) 1.316(4) 1.328(3) 1.333(4) 1.225(3) 1.220(3)

1.210(3)

1.226(3)

1.222(4)

Bond angles C10eN11eC12

121.3(4)

121.68(19)

121.44(19)

121.33(19)

121.0(3)

N11eC12eO1

122.9(4)

123.0(2)

123.8(2)

123.0(2)

124.2(3)

N11eC12eC13

114.3(4)

114.94(19)

115.67(19)

116.65(18)

115.8(2)

O1eC12eC13

122.8(4)

122.02(19)

120.6(2)

120.36(19)

120.0(3)

Dihedral angles o N1eC2eC10eN11

85.0(5)


59.9(3)


19.1(2)

0.7(3)


11.1(4)

N1eC2eC10eH10 C2eC10eN11eC12


89.4(4)

57 83.1(3)

96 101.4(2)


76.0(2)

105 105.3(3)

O1eC12eC13eN14

14.0(6)


0.7(3)


46.3(3)

38.4(3)


36.9(4)

C12eN11eC10eC16 C12eN11eC10eC17 a

Ref 28.


152.2(2)

120.9(2) 120.4(2) 122.2(3) 121.7(3) 116.9(2) 119.9(3) 120.8(2) 121.4(3) 11.1(4) 52.9(3)
79.2(3) 58.9(4) 28.2(3)
42.6(4)


131.2(2)
128.52(1)

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

C10 avoids the proximity of hydrogen bond donors toward the carbonyl group in this compound. Generally, the presence of substituents at the C10 and C13 positions determines the conformation of the organic fragment and contributes to the differences in the supramolecular patterns of salts 7e12. Therefore, bulky groups in C10 (R1) are placed in an antiperiplanar [C12eN11eC10eC16 ¼
152.2(2)o for compound 8] or anticlinal [C12eN11eC10eC16 ¼
131.2(2)o for compound 10 and C12eN11eC10eC17 ¼
128.52(1)o for compound 12] positions to the carbonylic group to avoid the steric repulsion produced by the lone pairs of the oxygen atom with the aliphatic substituents. Consequently, H10 in compounds 8 [R1 ¼ CH3], 10 [R1 ¼ CH(CH3)2] and 12 [R1 ¼ CH2CH(CH3)2] tend to be situated in synclinal [N1eC2eC10eH10 ¼ 57 for compound 8] or anticlinal [N1eC2eC10eH10 ¼ 96 for compound 10 and 105 for compound 12] positions with respect to the benzimidazole ring and modify the supramolecular patterns in these compounds. 3.2. Hydrogen bond interactions in salts 7e12 Halides favor supramolecular stabilization through hydrogen bond interactions [31,32]. Although the sum of van der Waals radii for H and Cl is 2.95 Å, hydrogen bonds at longer distances than this value have been reported. Thus, the intermolecular D-H∙∙∙Cl-M interactions in crystal structures have been categorized as “short” (2.52 Å), “intermediate” (2.52e2.95 Å) and “long” (2.95e3.15 Å) [33]. Similarly, bifurcated hydrogen bonds are frequently observed in systems containing excess acceptors compared with donors [34e36]. In compounds 7e12, the amino amide establishes hydrogen bonds with the tetrachlorozincate anion through the NeH groups (Table S3 in the supporting material). Hence, given the abundance of hydrogen bond donors in the form of NeH and the presence of four chlorine atoms in each ZnCl2
4 , the probability of

5

observing bifurcated donors (NeH) and bi-acceptors (Cl) in these salts is high. Interestingly, in the absence of solvent molecules in the crystalline cell [compounds 7 (R1 ¼ H, R2 ¼ CH3) and 12 (R1, R2 ¼ CH2CH(CH3)2)], ZnCl2
tends to interact with the organic 4 fragment through short and intermediate hydrogen bonds. This fact favors the presence of supramolecular chains running along the “b” axis in compounds 7 and 12. In both compounds, the benzimidazole nitrogen atoms are donor groups participating in hydrogen bonding interactions with tetrachlorozincate anions. Thus, in compound 7, the Cl4 atom acts as a bi-acceptor that forms N1eH1∙∙∙Cl4 [2.31(3) Å] and Cl4∙∙∙H3eN3 [2.48(3) Å] interactions. These interactions yield supramolecular chains with graph set C12 ð6Þ [-N1-H1∙∙∙Cl4∙∙∙H3eN3eC2-] (Fig. 1). Otherwise, in compound 12, the benzimidazole nitrogens participate in hydrogen bond interactions N1eH1∙∙∙Cl4 [2.65(4) Å] and Cl3∙∙∙H3eN3 [2.55(3) Å] that produce supramolecular chains with graph set C22 ð8Þ [-N1-H1∙∙∙Cl4eZn1eCl3∙∙∙H3eN3eC2-] (Fig. 2). Moreover, the bi-acceptor behavior of Cl4 produces two pseudo cycles in salt 7. The first cycle is a supramolecular synthon and results from N3eH3∙∙∙Cl4 and N11eH11∙∙∙Cl1 [2.46(3) Å] in[-N3teractions that provide a graph set R22 ð9Þ H3∙∙∙Cl4eZn1eCl1∙∙∙H11eN11eC10eC2-). In the network, adjacent synthons are linked by two N14eH14B∙∙∙O1 hydrogen bonds generating the centrosymmetric motifs R22 ð10Þ [-C12O1∙∙∙H14BeN14eC13eC12eO1∙∙∙H14BeN14eC13-] (Fig. 3). Unlike compound 7, the Cl4 atom in the salt 12 acts as a triacceptor. First, Cl4 serves as a pivot in a pseudo cycle. This pseudo cycle is a supramolecular synthon where N1eH1∙∙∙Cl4 [2.65(4) Å] and N14eH14A∙∙∙Cl4 [2.330(17) Å] interactions yield annular structures with graph set R12 ð10Þ [-C2-N1H1∙∙∙Cl4∙∙∙H14eN14eC13eC12eN11eC10-]. Additionally, each

Fig. 1. View of the supramolecular chain C12 ð6Þ [-N1-H1∙∙∙Cl4∙∙∙H3eN3eC2-] in compound 7 [28].

Fig. 2. View of the supramolecular chain C22 ð8Þ [-N1-H1∙∙∙Cl4eZn1eCl3∙∙∙H3eN3eC2-] in compound 12.

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Fig. 3. View of synthons linked by N14eH14B∙∙∙O1 hydrogen bonds that generate the centrosymmetric motifs R22 ð10Þ in compound 7.

synthon is linked to the other by N14eH14B∙∙∙Cl3 [2.37(3) Å] and N14eH14C∙∙∙Cl4 [2.73(4) Å] interactions, generating the centrosymmetric

motifs

R24 ð8Þ

[-N14-

H14A∙∙Cl4∙∙∙H14CeN14eH14A∙∙∙Cl4∙∙∙H14C] and R44 ð12Þ [-Zn1Cl3∙∙∙H14BeN14eH14A∙∙∙Cl4eZn1eCl3∙∙∙H14BeN14eH14ACl4-] (Fig. 4). X-ray studies appear to indicate that the co-crystallization of solvent molecules in salts 8e11 contributes to the formation of bifurcated hydrogen bonds. For example, in compound 8 [R1, R2 ¼ CH3], the N1eH1 group forms non-covalent interactions with O1 [2.331(18) Å] and Cl3 [2.53(2) Å]. The NHþ 3 group interacts with Cl1 and Cl2 atoms through the N14eH14c donor [2.87(2) Å and 2.70(3) Å, respectively]. Additionally, the Cl3 atom is a bi-acceptor that interacts with the benzimidazole group N1eH1 and a methanol molecule [2.53(2) Å] (Fig. 5).

Fig. 5. View of the supramolecular structure of salt 8. The presence of methanol stabilizes the pseudo cycle R66 ð22Þ.

On the other hand, as shown in Table S3, the N∙∙∙O bond lengths in hydrogen bonds of methanol molecules in compound 8 are shorter than N∙∙∙O bond lengths of water molecules in compounds 9e11. Nevertheless, the Nimidazolic∙∙∙Cl bond lengths are similar in salts 8e11. This fact corroborates the observation that methanol molecules are pivots that stabilize the supramolecular structure more effectively than water molecules and chloride atoms. Additionally, the presence of methanol in compound 8 contributes to the formation of pseudo-cycles with a large size (Fig. 5). Thus, two molecules of methanol hold together two organic fragments and two ZnCl2
4 anions and produce an annular system with graph set R66 ð22Þ [-N11-H11∙∙∙Cl4eZn1eCl3∙∙∙H2e O2∙∙∙H3eN3eC2eC10eN11eH11∙∙∙∙Cl4eZn1eCl3∙∙∙H2e O2∙∙∙H3eN3eC2eC10-]. The unitary cell in compound 9 [R1 ¼ H; R2 ¼ CH(CH3)2] comprises two organic fragments (9A and 9B) and two ZnCl2
4 anions (Fig. 6). The organic fragments are enantiomers with unlike conformations that yield different supramolecular patterns. Each enantiomer interacts with the other in similar manner by forming hydrogen bond interactions N14eH14a∙∙∙O1 [2.45(3) Å] and N31eH31a∙∙∙O2 [2.33(3) Å] to yield pseudo-cyclic dimers with graph set R22 ð10Þ. Additionally, the two tetrachlorozincate anions function as pivots that stabilize these dimers. Thus, the chlorine atoms of ZnCl2
4 interact with the organic fragments, forming a set of pseudo-cyclic structures. For example, the N1eH1 group interacts with the bifurcated form by forming bonds with Cl7 [2.85(4) Å] and Cl8 [2.546(18) Å] and produces an annular system with a graph set R 21 ð4Þ (-Zn2-Cl7∙∙∙H1∙∙∙Cl8-). In contrast, the Cl5 atom functions as a bi-acceptor, where N18eH18 [2.37(2) Å] and N31eH31C [2.59(4) Å] groups are hydrogen bond donors and yield

Fig. 4. View of synthons in compound 12 linked by N14eH14C∙∙∙Cl4 and N14eH14B∙∙∙Cl3 hydrogen bonds. These interactions generate the centrosymmetric motifs R12 ð10Þ and R44 ð12Þ.

a macrocyclic structure with graph set R 12 ð10Þ [-C29-C30-N31H31∙∙∙Cl5∙∙∙H18eN18eC17eC27eN28-]. Water molecules have a relevant role in stabilizing the supramolecular structures of compounds 10 [R1, R2 ¼ CH(CH3)2] and 11 [R1 ¼ H, R2 ¼ CH2CH(CH3)2] (Fig. 7). In both systems, the oxygen atom from water acts as a bi-acceptor and interacts with N1eH1

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

7

Fig. 6. View of the supramolecular structure of salt 9. N1eH1 acts as a bifurcated donor and Cl5 functions as a bi-acceptor in hydrogen bond interactions. The water molecule and methyl groups have been eliminated for clarity.

Fig. 7. Views of the pseudo-macrocyclic structure of compound 10 [graph set R66 ð20Þ] and supramolecular chain in compound 11 [graph set C33 ð10Þ].

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and N14eH14, yielding pseudo-cycles with graph set R12 ð10Þ [-N11C10-C2-N1-H1∙∙∙O2∙∙∙H14eN14eC13eC12-]. On the other hand, ZnCl2
4 anions form hydrogen bonds with water molecules and the NeH groups from organic fragments. However, the cation-anion interaction in the salt 10 leads to the formation of pseudo macrocyclic structures R66 ð20Þ [-C2-N3-H3∙∙∙Cl1eZn1eCl2∙∙∙H2e O2∙∙∙H1eN1eC2eN3eH3∙∙∙Cl1eZn1eCl2∙∙∙H2eO2∙∙∙H1e N1-], but in the organic-inorganic hybrid 11, these interactions produce supramolecular synthons containing the macrocycle with [-Zn1-Cl2∙∙∙H2BeO2∙∙H1eN1eC2e graph set R 33 ð11Þ C10eN11eH11∙∙∙Cl4-]. Moreover, synthons are linked by N3eH3∙∙∙Cl3 interactions, yielding supramolecular chains running along the b axis conformed by eN3H3∙∙∙Cl3eZn1eCl2∙∙∙H2eO2∙∙∙H1eN1eC2- atoms with graph set C33 ð10Þ. 3.3. p∙∙∙p interactions in salts 7e12 Facial p∙∙∙p interactions are generally present when the interplanar distance of two almost parallel aromatic rings is 3.3e3.8 Å (Table 3) [17]. Based on this criterion, p-stacking interactions contribute to supramolecular stabilization only in compounds 7e9. In these salts, substituents on C10 and C13 (-H or eCH3) exert a limited steric effect on the neighboring molecules. This phenomenon does not occur in compounds 10e12 that contain eCH(CH3)2 and eCH2CH(CH3)2 groups. The benzimidazole rings tend to stack in an antiparallel form in compounds 7e9. More effective stacking would occur when the imidazole ring (centroid Cg1) is parallel to the benzenoid ring (centroid Cg2 or Cg5) of a neighboring organic fragment or when the length between centroids Cg3∙∙∙Cg3 (annular system of nine members) is less than 3.8 Å (Fig. 8). In this manner, compounds 7 and 9A have shorter lengths of the Cg3∙∙∙Cg3 bond [3.662(3) Å and 3.7336(16) Å] than compounds 8 and 9B [3.8268(13) Å and 4.5330(16) Å]. Based on this result, p∙∙∙p interactions are preferentially promoted by charge transfer between both annular systems in compounds 7 and 9A [28].

Additionally, crystallographic studies revealed that the nature of the hydrogen bond is relevant to the p∙∙∙p interactions. When the two NeH groups of the benzimidazole group form hydrogen bond interactions with the tetrachlorozincate anion, the Cg(i) will be situated on the imidazole ring (Cg1 in compounds 7 and 9A). In contrast, if at least one NeH group interacts with a solvent molecule, the centroid Cg(i) will be located on the benzenoid ring (Cg2 in compound 8 and Cg5 in compound 9B). Thus, the charge transfer phenomenon is more relevant in ZnCl2
4 ∙∙∙HeN interactions than in NeH∙∙∙OH2 interactions [28]. Thus, the ZnCl2
4 ∙∙∙HeN interactions in compounds 7 and 9A will induce the polarization of the imidazole ring and the p∙∙∙p interaction occurs through the “dipole-induced dipole” phenomenon [17]. However, the two solvent molecules in compounds 8 and 9B do not have a negative charge and a low level of polarization of the imidazole due to hydrogen bond interactions will occur. Consequently, the p∙∙∙p interactions in these supramolecular systems will occur preferentially through “induced dipole-induced dipole” mechanisms. The p∙∙∙p interactions in compounds 7 and 9 lead to the formation of pseudo dimeric species that are connected by C] O∙∙∙HeN hydrogen bonds. This behavior produces a set of infinite chains. In compound 7, the chains run along the a axis and interact with other chains through ZnCl2
4 ∙∙∙H14eN14 hydrogen bonds. On the other hand, salt 9 comprises enantiomers 9A and 9B. The interactions of enantiomer 9A yield chains running along the b axis, whereas enantiomer 9B contains chains running along the ab axis (Fig. 9). Unlike compounds 7 and 9, the C]O group in compound 8 does not present intramolecular hydrogen bond interactions. Therefore, the p-stacking in salt 8 produces a pseudo dimeric species connected by tetrachlorozincate anions (Fig. 10). Thus, the ammonium group and tetrachlorozincate yield ZnCl2
4 ∙∙∙ HeN interactions that produce supramolecular patterns with graph set C22 ð6Þ (-Zn1Cl3∙∙∙H14b-N14-H14a∙∙∙Cl2-).

3.4. Hirshfeld surface analysis Table 3 p∙∙∙p interactions in systems 7e9. Compound

Cg(i); Cg(j)

d[Cg(i)∙∙∙Cg(j)] Å

7 8 9A 9B

i ¼ 1; i ¼ 2; i ¼ 1; i ¼ 5;

3.611(3) 3.6076(15) 3.5503(17) 3.617(2)

j¼3 j¼3 j¼3 j¼5

Fig. 8. Antiparallel stacking of two benzimidazole groups in compounds 7e9. Centroids Cg1, Cg2 and Cg3 result from 5, 6 and 9 annular systems, respectively.

A Hirshfeld surface analysis was performed to obtain additional information about the intermolecular interactions present in compounds 7e12. Fig. 11 shows the mapped surface of compound 7 for a range of dnorm from
0.631 to þ1.544. Moreover, the supporting material shows the surface analysis of the six amino amides. Notably, the depth red marks correspond to NeH∙∙∙O interactions. Additionally, the presence of NeH∙∙∙Cl hydrogen bonds produces red marks of lesser intensity and corroborates that these interactions are sufficiently strong to stabilize the supramolecular structure of amino amides 7e12. The white marks on the surface indicate the presence of the weakest CeH∙∙∙p, p ∙∙∙ p, and C∙∙∙O interactions. Quantitative information about the relative contribution of the intermolecular interactions was determined using 2D fingerprint plots (see Fig. 12 for compound 7). The blue surface shows the presence of the corresponding interaction. The relative contributions of H∙∙∙H, O∙∙∙H/H∙∙∙O, C∙∙∙H/H∙∙∙C, N∙∙∙H/H∙∙∙N, C∙∙∙C/C∙∙∙C and Cl∙∙∙H/H∙∙∙Cl are evidenced by the decomposition of the fingerprint plots. In Table 4 reports the percentage of the surface occupied by the corresponding interaction. Thus, the two principal contacts in compounds 7e12 correspond to H∙∙∙H and Cl∙∙∙H/H∙∙∙Cl. Moreover, the fingerprint plots reveal that as the volumes of R1 and R2 increase, the percentage of intermolecular participation of Cl∙∙∙H tends to decrease.

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

9

Fig. 9. Infinite chains formed by p∙∙∙p and hydrogen bond interactions in salts 7, 9A and 9B. Tetrachlorozincate anions have been eliminated for clarity.

3.5. Vibrational spectroscopies in salts 7e12

Fig. 10. Infinite chains formed by p∙∙∙p and ZnCl2
4 ∙∙∙HeN hydrogen bond interactions in compound 8.

Consistent with the results of the elemental analysis and crystallographic studies, the IR spectra of compounds 8e11 show the presence of hydrogen bonds with solvent molecules in the crystalline cell. In compound 8, an absorption signal at 3427 cm
1 is present and attributed to OeH stretching vibrations. This signal appears at lower frequencies than the signal observed for isolated methanol molecules (3700 cm
1) [37]. This behavior is also present in salts 9e11, where the crystalline cell contains water molecules [3514, 3500 and 3428 cm
1, respectively]. Consequently, the infrared spectra corroborate the presence of OeHCl hydrogen bonding interactions in compounds 8e11 [38]. Moreover, the IR spectra of salts 7e12 reveal the nature of the C]O∙∙∙HeN interactions. Compound 9 (1670 cm
1) presents a lower n C]O vibrational frequency of the set, but the vibration of the carbonyl group in compound 12 is shifted toward larger frequencies (1702 cm
1). These results are consistent with the crystallographic studies. The X-ray diffraction pattern reveals a lack of hydrogen bonds with the carbonyl group in compound 12. This behavior is attributed to the considerable steric effects exerted by the substituent groups at the C10 and C13 positions that change the molecular conformation and prevent any interaction with the oxygen O1. In contrast, the carbonyl oxygen in salts 7e9 and 11 tends to form hydrogen bonds with the NeH groups of neighboring molecules. In this manner, the frequency of the C]O vibration in compounds 7e9 and 11 is affected by the charge transfer phenomenon and the cooperativity of the non-covalent interactions.

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C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258 Table 4 Surface area (%) determined using 2D fingerprint plots contacts in compounds 7e12.

H∙∙∙H/H∙∙∙H O∙∙∙H/H∙∙∙O C∙∙∙H/H∙∙∙C N∙∙∙H/H∙∙∙N C∙∙∙C/C∙∙∙C Cl∙∙∙H/H∙∙∙Cl

Fig. 11. Hirshfeld surface map of compound 7 showing the dnorm property. Intermolecular NeH∙∙∙O and NeH∙∙∙Cl interactions are indicated by the deep dark red areas.

For example, as the C]O∙∙∙HeN angle increases, the vibrational frequency of C]O tends to decrease. In compounds 7 and 11, the hydrogen bond interactions are 173(5)o and 160(3)o and consequently, the C]O vibration in these compounds is shifted toward lower frequencies (1672 and 1684 cm
1, respectively) than C]O vibration in the compound 10 (1699 cm
1). These results provide evidence that the charge transfer phenomenon in hydrogen bond interactions of C]O is favored in compounds 7 and 11, but disfavored in compound 10. Likewise, the presence of bulky

7

8

9

10

11

12

32.9 7.0 9.5 3.0 4.5 36.9

39.5 8.4 7.6 3.1 5.1 31.8

38.6 8.5 11.4 1.3 2.2 32.6

49.5 10.1 4.4 1.6 4.5 27.2

38.6 16.8 12.6 2.8 0.7 25.5

50.5 5.3 12.8 2.4 0.0 26.7

substituents on C10 and C13 [R1 and R2 ¼ CH(CH3)2] effectively prevents the C]O group from interacting with any hydrogen bond donors in compound 10. On the other hand, IR spectra also provide evidence of the presence of a cooperativity phenomenon in salts 7e12.39 The X-ray diffraction pattern shows that carbonyl groups in compounds 8 and 9 function as bi-acceptors of hydrogen bond interactions (inter and intramolecular interactions). However, O∙∙∙N interaction distances are longer in salt 8 [2.973(2) Å for O1∙∙∙N1 and 2.960(3) Å for O1∙∙∙N14] than in salt 9 [2.764(4) Å for O1∙∙∙N14intra, 2.818(4) Å for O1∙∙∙N14inter, 2.676(3) Å for O2∙∙∙N31intra, and 2.802(3) Å for O2∙∙∙N31inter]. Based on these results, O1 forms stronger hydrogen bond interactions in compound 9 than in compound 8. These geometrical parameters are consistent with IR spectra of compounds 8 and 9. Thus, C]O vibrations have lower frequencies in compound 9 (1670 cm
1) than in compound 8 (1686 cm
1). Nevertheless, when the vibrational frequencies of C]O in compounds 8 and 9 are compared with compound 11, the cooperativity

Fig. 12. Decomposed 2D fingerprint plots of compound 7.

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

phenomena are evident. Despite the similar geometric parameters of the intermolecular O1∙∙∙H14eN14 interactions in compounds 9 and 11 (Table S3 in the supporting information), the corresponding signals for C]O vibrations appear at greater frequencies in compound 11 (1684 cm
1) than in compound 9 (1670 cm
1). This difference is due to the function of the carbonylic oxygen (O1) as a biacceptor atom in compound 9 and mono-acceptor in compound 11. Thus, the intramolecular interactions C]O∙∙∙H3N in compound 9 have important contributions to the lengthening of CeO bonds. This phenomenon is also present in salt 8. The presence of very weak interactions with O1 would cause the carbonyl group in compound 8 to display similar vibrational frequencies to compounds 10 (1699 cm
1) and 12 (1702 cm
1). However, the C]O frequencies in compound 8 are similar to the frequencies observed in compound 11. Therefore, the presence of two weak C]O∙∙∙ H3N interactions in compound 8 lengthen the CeO bonds in a similar manner to the stronger hydrogen bond in compound 11. By comparing the vibrational spectra with crystallography data, changes in the supramolecular structure of compounds 7e12 noticeably affect the Raman spectra. As mentioned above, the crystal structures of 7 and 12 do not contain molecules of dissolvent. Therefore, benzimidazole NeH groups only are interacting with chlorine atoms from tetrachlorozincate. In these compounds, the frequencies of NeH bending vibrations appear at 1562 cm
1. However, in the supramolecular structures of compounds 8 and 10 contain solvent molecules with oxygen atoms. Because the oxygen atoms of the solvent are capable of more efficiently donating lone pairs than the chlorine atoms of tetrachlorozincate, the presence of NeH∙∙∙O hydrogen bonds results in the lengthening of NeH bonds [28]. Thus, the NeH bending vibrations in compounds 8 and 10 are slightly shifted toward lower frequencies (1556 cm
1) than in compounds 7 and 12. Although the interaction distances N1∙∙∙O2 and N14∙∙∙O2 are shorter in compound 11 [2.787(3) Å and 2.863(3) Å, respectively] than in compound 10 [2.824(3) Å and 2.913(3) Å, respectively], the frequency of the NeH bending vibration in salt 11 is shifted toward higher frequencies [Dd ¼ 9 cm
1] than in compound 10. This behavior is due to the more efficient interaction of water molecules with two tetrachlorozincate anions in the crystal structure of compound 11 (Table S3). Thus, in the supramolecular structure of compound 11, the solvent molecules have larger negative charges around the oxygen atoms. Consequently, the electrostatic character of the NeH∙∙∙O interactions increases and the contraction of the NeH bond occurs. 4. Conclusions Organic-Inorganic hybrid compounds 7e12 were synthesized from amino amides and tetrachlorozincate anions to promote the formation of non-covalent interactions in the supramolecular structures of these compounds. Crystallographic studies revealed relevant roles for steric effects and the nature of the hydrogen bonds in the formation of p∙∙∙p interactions. Thus, although bulky substituents located on C10 and C13 reduce the efficacy of stacking phenomena, the NeH∙∙∙X (X ¼ Cl or O) interactions change the mechanism of p∙∙∙p interactions. The stacking phenomena is only observed in compounds with less bulky substituents (H or CH3). In this manner, p∙∙∙p interactions of the benzimidazole systems are present in salts 7e9, but not in compounds 10e12. Moreover, when the two NeH moieties of the benzimidazolium group form hydrogen bonds with the tetrachlorozincate anion, the Cg(i) will be located on the imidazole ring (Cg1 in compounds 7 and 9A). In contrast, if at least one of the NeH groups interacts with solvent molecules, the centroid Cg(i) will be located on the benzenoid ring (Cg2 in compound 8 and Cg5

11

in compound 9B). This behavior is a consequence of the greater importance of the charge transfer phenomenon in ZnCl2
4 ∙∙∙HeN interactions than in NeH∙∙∙solvent interactions. Therefore, the ZnCl2
4 ∙∙∙HeN hydrogen bonds in compounds 7 and 9a induce the polarization of the imidazole ring and the p∙∙∙p interactions occur through the “dipole-induced dipole” phenomenon. In the case of NeH∙∙∙solvent interactions (compounds 8 and 9B), the stacking phenomena will preferentially occur through the “induced dipoleinduced dipole” mechanism. On the other hand, IR spectroscopy corroborates that the function of O1 as a bi-acceptor atom lengthens C]O bonds and consequently shifts their vibrational frequencies toward lower values (compounds 8 and 9). Moreover, Raman spectra confirm that the presence of NeH∙∙∙O hydrogen bonds lengthens NeH bonds compared with ZnCl2
4 ∙∙∙HeN interactions. Acknowledgments This study was supported by SEP-CONACyT [grant CB-2011/ 169010]. C.A.-M. and E.I.T. thank CONACyT for providing scholarships (286215 and 23776, respectively). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.molstruc.2019.127258. References [1] S. Khalid, T.J. Piggot, F. Samsudin, Acc. Chem. Res. 52 (2019) 180. [2] L.-J. Chen, H.B. Yandg, Acc. Chem. Res. 51 (2018) 2699.
nchez, J. Contreras-García, A.J. Cohen, [3] E.R. Johnson, S. Keinan, P. Mori-Sa W. Yang, J. Am. Chem. Soc. 132 (2010) 6498. [4] X. Zhang, G.-P. Lu, Z.-B. Xu, C. Cai, ACS Sustain. Chem. Eng. 5 (2017) 9279. [5] T. Chen, M. Li, J. Liu, Cryst. Growth Des. 18 (2018) 2765. [6] D. Hamdane, C. Bou-Nader, D. Cornu, G. Hui-Bon-Hoa, M. Fontecave, Biochemistry 54 (2015) 4354. [7] A.N. Bootsma, S.E. Wheller, J. Chem. Inf. Model. 59 (2019) 149. [8] A. Zheng, J. Wang, N. Xu, R. Zhu, Y. Yuan, J. Zhang, J. Zhang, Z. Li, P. Wang, Photonics 5 (2018) 4694. [9] M.P. Parker, C.A. Murray, L.R. Hart, B.W. Greenland, W. Hayes, C.J. Cardin, H.M. Colquhoun, Cryst. Growth Des. 18 (2018) 386. [10] N. Pobsuk, T.U. Paracha, N. Chaichamnong, N. Salaloy, P. Suphakun, S. Hannongbua, K. Choowongkomon, D. Pekthong, K. Chootip, K. Ingkaninan, M. Paul Gleeson, Bioorg. Med. Chem. Lett. 29 (2019) 267e270. [11] H. Sun, W. Tan, Y. Zu, Analyst 141 (2016) 403. [12] S. Prabhu, S. Vijayakumar, P. Manogar, G.P. Maniam, N. Govindan, Biomed. Pharmachother. 92 (2017) 528. [13] M. Orlandi, J.A.S. Coelho, M.J. Hilton, F.D. Toste, M.S. Sigman, J. Am. Chem. Soc. 139 (2017) 6803. [14] J. Wang, K. Liu, R. Xing, X. Yan, Chem. Soc. Rev. 45 (2016) 5589. [15] J. Pan, D. Cao, F. Ren, J. Wang, L. Yang, J. Mol. Model. 24 (2018) 298. [16] A.S. Mahadevi, G.N. Sastry, Chem. Rev. 116 (2016) 2775. [17] C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885. [18] C.A. Hunter, J.K.M. Sanders, J. Am. Chem. Soc. 112 (1990) 5525. [19] V.R. Mishra, C.W. Ghanavatkar, S.N. Mali, S.I. Qureshi, H.K. Chaudhari, N. Sekar, Comput. Biol. Chem. 78 (2019) 330. [20] E. Mentes¸e, F. Yilmaz, M. Emirik, S. Ülker, B. Kahveci, Bioorg. Chem. 76 (2018) 478. [21] N. Siddiqui, M.S. Alam, R. Ali, M.S. Yar, O. Alam, Med. Chem. Res. 25 (2016) 1390. ~ o, [22] M. Rodriguez-Cordero, N. Cigüela, L. Llovera, T. Gonz
alez, A. Bricen
n, Inorg. Chem. Commun. 91 (2018) 124. V.R. Landaeta, J. Rastra
n-Leo
n, F. Sa
nchez-De Jesús, R.E. Moo[23] V. Lechuga-Islas, H. Tlahuext, M.P. Falco Puc, J.B. Chale-Dzul, A.R. Tapia-Benavides, M. Tlahuextl, Eur. J. Inorg. Chem. (2018) 1419. [24] D.P. Malenov, G.V. Janji
c, V.B. Medakovi
c, M.B. Hall, S.D. Zari
c, Coord. Chem. Rev. 345 (2017) 318. [25] J.M. Andri
c, I.S. Antonijevi
c, G.V. Janji
c, S.D. Zari
c, J. Mol. Model. 24 (2018) 60. [26] P. Mignon, S. Loverix, J. Steyaert, P. Geerlings, Nucleic Acids Res. 33 (2005) 1779. [27] S. Saha, G.N. Sastry, J. Phys. Chem. B 119 (2015) 11121.
n-Leo
n, A. Ariza-Castolo, [28] C. Avila-Montiel, A.R. Tapia-Benavides, M. Falco H. Tlahuext, M. Tlahuextl, J. Mol. Struct. 1100 (2015) 338. [29] Agilent CrysAlis PRO, Agilent Technologies, 2011. Yarnton. [30] G.M. Sheldrick, SHEIX86, Program for Crystal Structure Solution, University of

12

C. Avila-Montiel et al. / Journal of Molecular Structure 1202 (2020) 127258

€ttigen, Germany, 1986. Go
n, D. Bellamy, L. Brammer, E.A. Bruton, A.G. Orpen, Chem. Commun. [31] G. Aullo (1998) 653. [32] L. Brammer, E.A. Bruton, P. Sherwood, Cryst. Growth Des. 1 (2001) 277. [33] A.J. Bondi, J. Chem. Phys. 68 (1964) 441. [34] G.A. Jeffrey, W. Saenger, Hydrogen Bonding in Biological Structures, SpringerVerlag, Berlin, Heidelberg, 1991.

[35] G.A. Jeffrey, Crystallogr. Rev. 4 (1995) 2013. [36] G.A. Jeffrey, An Introduction to Hydrogen Bonding, Oxford University Press, New York, 1997. [37] G. Boehm, M. Dwyer, J. Chem. Educ. 58 (1981) 809. [38] J.R. Roscioli, E.G. Diken, M.A. Johnson, S. Horvath, A.B. McCoy, J. Phys. Chem. A 110 (2006) 4943.