Novel Salts of Heterocyclic Polyamines and 5-Sulfosalicylic Acid: Synthesis, Crystal Structure, and Hierarchical Supramolecular Interactions

Abstract

A series of novel salts of heterocyclic polyamines with 5-sulfosalicylic acid (C₄H₇N₄⁺)(C₇H₅O₆S⁻)∙2(H₂O) (1), (C₄H₆ClN₄⁺)(C₇H₅O₆S⁻)∙H₂O (2), (C₅H₈N₃⁺)(C₇H₅O₆S⁻)∙H₂O (3), (C₅H₇N₆⁺)(C₇H₅O₆S⁻)∙H₂O (4), (C₆H₁₄N₂²⁺)(C₇H₄O₆S²⁻)∙H₂O (5), and (C₁₄H₁₉N₂⁺)(C₇H₅O₆S⁻) (6) have been successfully synthesized. Their crystal structures have been determined by single-crystal X-ray diffraction. Overall, compounds adopt a layered structure with aminium cations and 5-sulfosalicylic anions linked via water molecules. The solid-state architectures of these compounds are dominated by O(N,H)-H⋯O and N-H⋯N hydrogen bonds and stabilized by weak interconnects. C-Cl⋯π and S-O⋯π interactions, apart from π⋯π and C-H(O)⋯π, were reported. Diverse approaches were used to study the effect of substituents in the polyamines in solid-state arrangement. A Hirshfeld surface analysis, with associated 3D Hirshfeld surface maps and 2D fingerprint plots, molecular electrostatic potential, and energy frameworks were used to comprehensively investigate the nature and hierarchy of non-covalent interactions and inspect supramolecular differences. The contact enrichment ratio calculations provided deeper insight into the propensity of interconnects to influence crystal packing. The evaluation of the effects of H-bonding synthons resulting from different substituents in the polyamines on self-assemblies is also presented. In the context of crystal engineering, a specific intramolecular synthon via O-H⋯O observed in nearly all crystals can be employed in the pseudo-cyclic replacement strategy in the design of new molecules.

1. Introduction

Organic salts based on 2-hydroxy-5-sulfobenzoic (5-sulfosalicylic) acid are eagerly studied due to their interesting optical and pharmaceutical properties [1,2,3,4,5,6]. Many salts, including one negative 3-carboxy-4-hydroxybenzenesulfonate anion, C₇H₅O₆S⁻ (with a negative charge at the sulfonyl group), have been presented. These include compounds mostly with organic [7,8,9,10] but also inorganic cations [11,12]. Still, there are only a few of its salts with cations originating from pyrimidine. One salt with 2-aminopyrimidin-1-ium ion [13] and two with 2,4-diaminopyrimidin-1-ium ion derivatives can be distinguished. Among these 2,4-diaminopyrimidin-1-ium ions, the first has the trimethoxybenzyl group in the 5-position of the pyrimidine ring [14], and the second o-chlorophenyl and ethyl groups in the 5- and 6-positions, respectively [15]. The 2,4-diaminopyrimidin-1-ium cation has been reported in several ion pairs with simple inorganic [16] and some organic anions [17,18,19,20,21]. The crystal structures of a series of 2,4-diaminopyrimidin-1-ium salts with chain dicarboxylate ions have been discussed by us recently [22].

Of the presented organic connections, only the crystal structure of salt 3, derived from 5-sulfosalicylic acid and 2,6-diaminopyridine, has been measured at room temperature earlier [23]. In addition, the crystal structure of the C₇H₅O₆S⁻ and 2,3-diaminopyridinium ion pair has also been reported [24]. Moreover, a few other structures with 2-aminopyridinium ion [13] and its derivatives substituted by chloro [25,26], bromo [27] or methyl [28] group can be found in the CSD. For 2,6-diamino-9H-purin-1-ium cation, only its salts with 2-(2-carboxylatophenyl)acetate and closo-dodecafluorododecaborate (B₁₂F₁₂²⁻) anions have been described [29,30]. In turn, for 3-carboxy-4-hydroxybenzenesulfonate anion, its salts with 9H-purin-6-aminium, 6-aminopurin-1-ium and 6-(benzylamino)-9H-purin-1-ium cations have been reported [31,32]. The ion pairs of 8-(dimethylamino)-N,N-dimethylnaphthalen-1-aminium (dmanH⁺) and the salicylic acid derivatives have also been discussed [33,34].

Recently, salts of the dipositive 1,4-diazabicyclo[2.2.2]octane-1,4-diium cation (dabcoH₂²⁺) have been widely presented as attractive materials for use in opto-electronics [35,36,37,38,39,40]. In addition, crystal structures containing 3-carboxylato-4-hydroxybenzenesulfonate dianion, C₇H₄O₆S²⁻ (with a negative charge at both sulfonyl and carboxyl groups), and singly or doubly charged organic cations have been structurally characterized [1,41,42,43,44]. Among them, the salts of C₇H₄O₆S²⁻ with 2-aminopyridinium [45], 2,6-diaminopyridinium [46] 2-amino-4,6-dimethylpyrimidinium [47], and 6-(benzylamino)-3H-purin-7-ium ions [48] can also be distinguished.

N-rich heterocyclic polyamines, together with popular multifunctional 5-sulfosalicylic acid, have received a lot of interest in both academic and industrial studies and applications as building blocks of appealing multifunctional supramolecular architectures. Supramolecular chemistry, as a key branch of crystal engineering, has wide implications in the rational design of novel compounds, especially in the context of control of the self-organization and, in further consequence, predictable and desirable structural complex assemblies (such as salts or co-crystals). H-bonding, as well as other non-covalent interactions, have emerged to be the most important tool in crystal engineering [49,50,51]. Organic crystals composed of specific functional groups with diverse applications attracted much attention in the context of the predictable assemblies of supramolecular architectures. The utilization of self-assembly of small compounds with either strong O(N)-H⋯O or weak C-H⋯O hydrogen bonds, halogen bonds, and π-based interactions to the formation and stabilization of 3D supramolecular networks is a vital aspect. The rational design of well-defined structures from complex multifunctional moieties is possible via supramolecular synthons—structural units within crystals composed of hydrogen bonds and/or other non-covalent interactions [52]. The synthons can be classified as homo- or heterosynthons, which are formed from self-complementary half units and different components/functionalities, respectively [53].

Considering all these points in the course of our supramolecular studies on the hierarchy of non-covalent interactions [22,54,55,56,57] here, we report the synthesis and thorough supramolecular investigations of the series of new salts, namely, 2,4-diaminopyrimidin-1-ium 3-carboxy-4-hydroxybenzenesulfonate dihydrate (1), 2,4-diamino-6-chloropyrimidin-1-ium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (2), 2,6-diaminopyridin-1-ium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (3), 2,6-diamino-9H-purin-1-ium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (4), 1,4-diazabicyclo[2.2.2]octane-1,4-diium 2-hydroxy-5-sulfonatobenzoate monohydrate (5), and 8-(dimethylamino)-N,N-dimethylnaphthalen-1-aminium 3-carboxy-4-hydroxybenzenesulfonate (6) (Figure 1). It should be mentioned that these structures have not previously been structurally authenticated. They are presented for the first time to the best of our knowledge; only one salt (3) is a better re-determination, at low temperatures with a higher precision, of previously published structure (CSD refcode: KAXAE) [23]. These compounds can construct appealing supermolecules and diverse either strong or weak synthons because of the presence of a large amount of oxygen and nitrogen atoms, excellent acceptors and donors, and different functional groups such as the sulfonic, carboxylic, hydroxyl, amino, and methyl groups. In addition, water solvent molecules offer an enriched portfolio of H-bonding patterns. This study was undertaken to understand the nature and relevance of the hierarchy of non-covalent interactions either between the cations or between the anions, as well as the cation–anion interplay, focusing on the effect of the H-bonding synthons on novel self-assemblies. The analysis of interaction preferences was supported by Full Interaction Maps. The supramolecular topology of H-bonding networks was examined by an extended Hirshfeld surface analysis, including the enrichment ratios, the molecular electrostatic potentials, and the energy frameworks.

2. Materials and Methods

2.1. Synthesis of Compounds 1–6

The commercially available chemicals were of reagent grade and used as received. The ATR-FTIR spectra were recorded on a Thermo Scientific Nicolet iS10 FTIR spectrometer using the ATR technique with ZnSe crystal. The following procedure was applied to obtain the requested crystals of heterocyclic polyamines and 5-sulfonylsalicylic acid.

The 5-sulfosalicylic acid (0.1 mmol, 1 equiv., 22 mg) and appropriate organic diamine (0.1 mmol, 1 equiv., 11 mg of 2,4-diaminopyrimidine, 15 mg of 2,4-diamino-6-chloropyrimidine, 11 mg of 2,6-diaminopyridine, 15 mg of 2,6-diaminopurine, 12 mg of 1,4-diazabicyclo[2.2.2]octane, and 22 mg of 1,8-bis(dimethylamino)naphthalene) were dissolved in 2 mL of warm distilled water, the solution was filtered through a small cotton pad and left in the room temperature for solvent evaporation (about two weeks). The obtained crystals of the salts were used for the X-ray measurements and recording the ATR-FTIR spectra.

Compound 1: ATR-FTIR (ZnSe), ν_max/cm⁻¹: 3434 s, 3350 s (N–H), 3245 m (N–H), 3089 w (C–H), 3039 w (C–H), 2952 w, 2837 w, 1658 vs (C=O), 1636 m sh (C–O), 1606 sh (C–O), 1519 m, 1475 w, 1451 w, 1395 w, 1334 w (SO₃), 1295 w, 1236 sh, 1211 m sh (SO₃), 1169 s (SO₃), 1156 sh (SO₃), 1119 m, 1078 w, 1034 m, and 792 w.

Compound 2: ATR-FTIR (ZnSe), ν_max/cm⁻¹: 3507 m, 3455 w (N–H), 3304 m br (N–H), 3117 s, 2772 w br, 1665 vs (C=O), 1652 sh (C=O), 1605 m (C–O), 1551 m (C–O), 1530 w, 1479 w, 1371 w (SO₃), 1305 w, 1217 m (SO₃), 1169 s (SO3), 1151 s (SO₃), 1126 s, 1079 m, 1032 s, 987 m, 796 w, 711 w, and 664 w.

Compound 3: ATR-FTIR (ZnSe), ν_max/cm⁻¹: 3471 m, 3424 m, 3372 m (N–H), 3343 (N–H), 3271 m, 3221 m, 3124 w, 3096 w (C–H), 3075 w (C–H), 2974 w br, 2863 m br, 2790 m br, 2703 w br, 1652 vs (C=O), 1631 s (C=O), 1582 m (C–O), 1474 w, 1432 w, 1406 w, 1303 w (SO₃), 1225 m (SO₃), 1208 m (SO₃), 1169 m sh (SO₃), 1158 m (SO₃), 1144 m, 1116 s, 1017 s, 922 w, 830 w, 775 w, 714 w, and 662 w.

Compound 4: ATR-FTIR (ZnSe), ν_max/cm⁻¹: 3397 vs br, 3360 vs br (N–H), 3209 vs br (N–H), 3048 m (C–H), 2851 w br, 1655 s sh (C=O), 1619 s (C=O), 1588 s sh (C–O), 1478 m, 1437 m, 1406 w, 1377 w (SO₃), 1347 w sh, 1156 m (SO₃), 1125 m (SO₃), 1086 w, 1029 w, and 668 w.

Compound 5: ATR-FTIR (ZnSe), ν_max/cm⁻¹: 3394 w br (N–H), 3045 w (C–H), 2566 w vbr, 1644 w (C=O), 1595 m (C–O), 1474 m, 1377 w (SO₃), 1291 w, 1270 w, 1291 s (SO₃), 1180 s (SO₃), 1159 m (SO₃), 1145 s (SO₃), 1122 s, 1084 m, 1076 m, 1057 w, 1034 s, 1021 vs, 888 w br, 832 m, 777 w br, 728 w, and 668 s.

Compound 6: ATR-FTIR (ZnSe), ν_max/cm⁻¹: 3050 w (C–H), 3004 w (C–H), 2973 w, 1662 m (C=O), 1603 m (C–O), 1585 w, 1474 m, 1465 m, 1288 w, 1250 s (SO₃), 1216 s (SO₃), 1188 w, 1157 m (SO₃), 1140 s (SO₃), 1119 m, 1080 m, 1016 vs, 885 w, 841 m, 831 m, 784 w, 767 m, 746 w br, 711 m, and 664 m.

2.2. Single-Crystal X-ray Diffraction

Diffraction data of single crystals of the studied compounds were collected at T = 100 K using a mirror-monochromated Cu Kα radiation (λ = 1.54184 Å) from a microfocus Nova X-ray source on a Rigaku SuperNova (dual source) four-circle diffractometer operating with an Eos CCD detector. CrysAlis PRO software (version CrysAlisPro 1.171.41.112a) was used to perform data collection and reduction, and multi-scan absorption correction. Direct method and full matrix least-squares treatment on F² data were applied to solve and refine the crystal structures. All non-hydrogen atoms were refined with anisotropic atomic displacement parameters. Hydrogen atoms bonded to carbon atoms were placed in calculated positions and refined isotropically as a riding model with standard parameters. The H atoms bonded to the N and O atoms were located from a different Fourier map, and their positions were freely refined. All calculation procedures were carried out using SHELXTL programs [58], integrated with the OLEX2 crystallographic software (version 1.3) [59]. Mercury (version 2023.3.1) [60] and PLATON (version 2023.1) [61] programs were applied for the graphical representation of the structures and geometry analysis.

2.3. Computational Details

2.3.1. Full Interaction Maps

3D Full Interaction Maps (FIMs) based on CSD interaction data [62] for all analyzed crystals to check their preferred interaction behavior were calculated using Mercury software [60]. This tool generates the landscape of interactions using 3D coordinates from an X-ray experiment. The comparison of the predicted most likely positions of functional groups with a crystal packing can help evaluate whether a corresponding crystal fulfills the desired interactions.

2.3.2. Hirshfeld Surface Analysis

A Hirshfeld analysis was performed using the newest version of CrystalExplorer 21.5 [63,64]. The 3D maps of the Hirshfeld’s surfaces revealing qualitative information on non-covalent interactions were mainly mapped with the d_norm property by a colored scheme, where red spots denote the shortest inter-contacts, the white regions illustrate distances close to the van der Waals (vdW) contacts (d_norm equal to zero), and the blue areas signify the interactions longer than the sum of the vdW radii (positive values of d_norm) [64]. The map was generated by calculation of the normalized distances from the contact points on the surface to the nearest nucleus inside (d_i) or outside (d_e) the Hirshfeld surface where all H-bond lengths adopted the neutron-derived values [65]. Two-dimensional fingerprint plots, drawn as a function of d_i and d_e values, reveal quantitative data on close inter-contacts [64].

2.3.3. Molecular Electrostatic Potential

The molecular electrostatic potential mapped onto Hirshfeld surfaces was obtained at the wave function of the HF/STO-3G level using Crystal Explorer 21.5 [63,66].

2.3.4. The Enrichment Ratio

The enrichment ratios (ER) of the intermolecular interactions in the analyzed crystal structures 1–6 were calculated based on the HS methodology. ER for an element pair (X, Y) is the ratio of the actual percentage of random inter-contacts within the crystal (CXY) to the percentage of theoretically equivalently distributed random contacts (RXY), when EXY = CXY/RXY. In this way privileged (when ER > 1) and disfavored inter-contacts (ER < 1) can be highlighted in the crystal structures [67].

2.3.5. Energy Frameworks

The pairwise interaction energies between the moieties within the crystal were computed by Crystal Explorer 21.5 program [63,64,66,68,69] using the wavefunction calculated at the B3LYP/6-31G(d,p) functional basis set that is widely accepted in computational chemistry. The electrostatic (E_ele), polarization (E_pol), dispersion (E_disp), and exchange repulsion (E_rep) energy components, according to Equation (1), were obtained. More specifically, the electrostatic term is characterized by the forces among charged particles, the polarization term is concerned with the interactions resulting from the distortion of a molecule’s electron cloud via other near-charge distributions, dispersion term is considered to be the weak forces caused by fluctuations in a molecule’s electron distribution, while repulsion term means the energy needed to overcome the forces that prevent a molecules pair from interaction [70,71].

To calculate the total energy (E_tot) framework, a molecular cluster with a radius of 3.8 Å was generated around a selected single moiety of the reference compound. Symmetry operations were applied to build molecular wave functions and calculate the electron densities of a cluster. A tube size of 100 was used for the images.

E_tot = E_ele + E_pol + E_disp + E_rep

(1)

3. Results and Discussion

3.1. X-ray Structure and Supramolecular Features

The crystal structures of 1–6 were determined by single crystal X-ray diffraction with high precision at low temperature. Crystals 1, 2, 4, 5, and 6 are novel, while 3 is a better equivalent of the previously published structure KASXAE, which was earlier determined at ambient temperature [23]. The molecular structures of 1–6 are shown in Figure 2. Compounds 1, 2, 4, and 5 crystallize in the triclinic P$\overline{1}$ space group, while compounds 3 and 6 crystallize in the monoclinic space groups—P2₁ and P2₁/c, respectively. Full crystallographic data of studied salts are collected in

Table 1. Crystal data and structure refinement details obtained from measurements at 100 K for the studied compounds.

Compound	1	2	3	4	5	6
Chemical formula	C11H16N4O8S	C11H13ClN4O7S	C12H15N3O7S	C12H14N6O7S	C13H20N2O7S	C21H24N2O6S
Formula weight	364.34	380.76	345.33	386.35	348.37	432.48
λ (Cu Kα) (Å)	1.54184	1.54184	154184	1.54184	1.54184	1.54184
Crystal system	triclinic	triclinic	monoclinic	triclinic	triclinic	monoclinic
Space group	P$\overline{1}$	P$\overline{1}$	P 21	P$\overline{1}$	P$\overline{1}$	P 21/c
a (Å)	7.9539(3)	6.8906(6)	6.6358(2)	6.6755(4)	6.7903(4)	19.7312(3)
b (Å)	9.5529(4)	6.9077(6)	12.9481(4)	10.6495(5)	8.7284(8)	12.33559(11)
c (Å)	11.2394(4)	16.9140(11)	8.4812(3)	10.9153(5)	13.3336(7)	18.4437(3)
α (°)	67.904(4)	96.621(6)	90	84.427(4)	101.707(6)	90
β (°)	85.375(3)	96.880(6)	104.703(3)	87.076(5)	103.408(5)	114.7954(16)
γ (°)	78.700(3)	108.636(8)	90	83.698(5)	94.585(6)	90
Volume (Å)	775.92(6)	747.20(11)	704.84(4)	767.01(7)	746.02(9)	4075.28(10)
Z	2	2	2	2	2	8
Dcalc (g·cm−3)	1.559	1.692	1.627	1.673	1.551	1.775
μ (mm−1)	2.344	4.022	2.470	2.405	2.312	1.410
F (000)	380	392	360	400	368	1824
Crystal size (mm)	0.18 × 0.16 × 0.08	0.15 × 0.08 × 0.03	0.18 × 0.10 × 0.05	0.22 × 0.04 × 0.03	0.18 × 0.14 × 0.10	0.20 × 0.18 × 0.10
θ range (°)	4.245–70.422	2.667–70.282	5.392–70.328	4.073–70.352	3.500–70.225	2.467–70.187
Reflections collected	11,295	5414	4501	9276	4728	28,523
Unique reflections	2926	2792	2451	2858	2776	7674
Reflections I > 2σ(I)	2805	2419	2365	2484	2513	6949
Rint	0.0220	0.0290	0.0211	0.0361	0.0187	0.0222
Restraints/parameters	1/261	1/253	1/244	0/274	1/223	2/567
Goodness-of-fit	1.086	1.116	1.073	1.073	1.047	1.043
R1, wR2 (I > 2σ(I))	0.0261, 0.0735	0.0379, 0.0986	0.0276, 0.0695	0.0432, 0.1096	0.0335, 0.0853	0.0303, 0.0827
R1, wR2 (all data)	0.0273, 0.0745	0.0443, 0.1047	0.0293, 0.0716	0.0533, 0.1161	0.0373, 0.0881	0.0338, 0.0855
Max. peak/hole (e·Å−3)	0.359/−0.468	0.307/−0.602	0.202/−0.298	0.674/−0.473	0.398/−0.427	0.302/−0.482
K.P.I. [%]	70.2	72.6	72.7	74.2	70.6	74.4

K.P.I.—Kitaigorodsky’s packing index.

. The unit cells of 1–5 contain solvent (water) molecules, apart from aminium cation and 5-sulfosalicylate anion. The unit cell of 6 consists of two crystallographically independent cations and anions. The structure of 5 represents the dicationic and dianionic species. The deprotonated carboxylic (COO⁻) and sulfonic (SOO⁻) groups of the anion show bond lengths of 1.275 and 1.261, as well as 1.453 and 1.456 Å, respectively. It indicates a delocalized anionic charge. Selected bond lengths and angles of 1–6 can be found in Table S1. The values are comparable to those found in the literature.

The crystal packing can be quantified by the Kitaigorodsky packing index (K.P.I.) [72,73]. It was calculated with the ‘calc void’ procedure implemented in the PLATON program [61]. The results showed that 6 is the most, while 1 is the least closely packed structure with 74.4% and 70.2% of filled space, respectively. No space accessible for voids was found (Table 1). The appealing feature of analyzed salts is the presence of diverse functional groups (sulfonate, carboxyl, hydroxyl, amine, methyl) with available H-atom donor and acceptor atoms of both cation and anion species, as well as water molecules, which results in extensive H-bonding interactions. The crystal packing of all salts is formed mainly by O-H⋯O, N-H⋯O, and C-H⋯O interactions, with the distances shorter than the sum of the mean van der Waals radii of the two corresponding atoms, from 1.63 Å for O-H⋯O in 4 and 6 to 2.59 Å for C-H⋯O in 5. Furthermore, O-H⋯N in 1 and N-H⋯N interactions in 2, 4, and 6 are observed. The intramolecular network is affected by O-H⋯O and C-H⋯O, and also N-H⋯N in 6. The geometrical parameters of H-bonds are listed in

Table 2. Geometric parameters of H-bonds for 1–6.

9	D-H [Å]	H⋯A [Å]	D⋯A [Å]	D-H⋯A [o]
1
N1-H1⋯O2 i	0.883(19)	1.869(19)	2.7472(14)	172.7(17)
N3-H3A⋯O8 ii	0.886(19)	2.154(19)	2.9655(16)	152.1(17)
N3-H3B⋯O5 iii	0.853(19)	2.136(19)	2.9698(16)	165.5(19)
O4-H4⋯O7	0.90(2)	1.69(2)	2.5685(13)	166(3)
N4-H4A⋯O6 ii	0.857(19)	2.141(19)	2.9205(17)	151.1(17)
N4-H4B⋯O3 iv	0.869(19)	2.082(19)	2.9313(16)	165.5(18)
*O6-H6⋯O5	0.86(2)	1.87(2)	2.6397(14)	149(2)
O6-H6⋯N2 iii	0.86(2)	2.44(2)	2.9052(15)	114.9(17)
O7-H7A⋯O1 v	0.83(2)	1.96(2)	2.7803(14)	172(2)
O7-H7B⋯O8	0.84(2)	1.90(2)	2.7306(15)	168(2)
O8-H8A⋯O3 iv	0.81(2)	2.10(2)	2.8640(14)	157(2)
O8-H8B⋯O1 vi	0.85(3)	1.93(3)	2.7594(15)	166(2)
*C2-H2⋯O3	0.95	2.53	2.9197(17)	105
C5-H5⋯O1 vii	0.95	2.57	3.2961(16)	134
C10-H10⋯O4 iv	0.95	2.54	3.2942(18)	137
C11-H11⋯O7 iv	0.95	2.42	3.3590(18)	168
(i) 1 − x, 1 − y, 2 − z; (ii) x, y, 1 + z; (iii) −x, 2 − y, 1 − z; (iv) 1 − x, 1 − y, 1 − z; (v) −x, 1 − y, 1 − z; (vi) x, 1 + y, −1 + z; (vii) −x, 1 − y, 2 − z
2
O1-H1⋯O4 i	0.80(3)	1.93(3)	2.666(3)	154(3)
N2-H2⋯O6	0.94(4)	1.84(4)	2.758(3)	166(3)
*O3-H3⋯O2	0.89(4)	1.85(4)	2.615(3)	144(3)
N3-H3B⋯N1 ii	0.87(3)	2.10(3)	2.953(3)	170(3)
N3-H3C⋯O5	0.89(4)	1.98(3)	2.862(3)	169(3)
N4-H4A⋯O2 iii	0.86(3)	2.08(3)	2.925(3)	168(3)
N4-H4B⋯O7	0.92(4)	1.92(4)	2.813(3)	163(3)
O7-H7A⋯O5 iv	0.82(3)	2.02(3)	2.838(3)	174(3)
O7-H7B⋯O6 v	0.78(5)	2.11(5)	2.867(3)	164(5)
C3-H3A⋯O3 vi	0.95	2.54	3.355(4)	144
*C6-H6⋯O4	0.95	2.48	2.885(3)	106
C6-H6⋯O1 i	0.95	2.54	3.339(3)	142
(i) 3 − x, 1 − y, 1 − z; (ii) 1 − x, −y, −z; (iii) 2 − x, 1 − y, 1 − z; (iv) −1 + x, 1 + y, z; (v) −1 + x, y, z; (vi) 1 − x, −y, 1 − z
3
N1-H1⋯O7	0.86(4)	1.91(4)	2.754(4)	170(4)
N2-H2A⋯O3 i	0.85(5)	2.38(5)	3.206(3)	163(4)
N3-H3A⋯O6 ii	0.85(5)	2.24(5)	3.012(3)	152(4)
N3-H3B⋯O2 iii	0.87(4)	2.09(4)	2.924(3)	162(4)
O4-H4⋯O1 iii	0.88(4)	1.76(4)	2.613(2)	165(4)
*O6-H6⋯O5	0.80(5)	1.89(5)	2.606(3)	148(5)
O7-H7A⋯O3	0.81(5)	2.07(5)	2.842(4)	161(5)
O7-H7B⋯O1 iv	0.81(5)	2.00(5)	2.768(3)	160(5)
*C2-H2⋯O3	0.95	2.53	2.917(4)	104
(i) 1 − x, −1/2 + y, 2 − z; (ii) 1 − x, ½ + y, 1 − z; (iii) x, y, −1+z; (iv) 1 + x, y, z
4
N2-H2A⋯O7	0.91(3)	1.84(3)	2.730(3)	166(3)
O4-H4⋯N3 i	0.97(4)	1.63(4)	2.573(2)	165(4)
N4-H4A⋯N1 ii	0.87(3)	2.04(3)	2.891(3)	170(3)
N5-H5A⋯O7	0.88(3)	2.36(3)	3.091(3)	141(3)
N5-H5B⋯O2 iii	0.84(3)	1.99(3)	2.817(3)	170(3)
*O6-H6⋯O5	0.86(3)	1.82(3)	2.594(2)	150(3)
N6-H6B⋯O3	0.89(3)	1.94(3)	2.781(3)	159(2)
N6-H6C⋯O5 iv	0.84(3)	2.02(3)	2.851(3)	168(3)
O7-H7A⋯O1 v	0.83(4)	2.07(4)	2.827(3)	153(4)
O7-H7B⋯O3 vi	0.80(4)	2.09(4)	2.877(3)	165(3)
*C2-H2⋯O3	0.95	2.47	2.868(3)	105
C5-H5⋯O6 vii	0.95	2.58	3.455(3)	153
C11-H11⋯O2 viii	0.95	2.37	3.098(3)	133
(i) x, 1 + y, z; (ii) 1 − x, −y, 2 − z; (iii) x, y, 1 + z; (iv) x, −1 + y, z; (v) −x, 1 − y, 1 − z; (vi) 1 − x, 1 − y, 1 − z; (vii) −x, 2 − y, −z; (viii) 1 − x, −y, 1 − z
5
N1-H1⋯O6 i	0.91(2)	1.84(2)	2.7102(18)	161(2)
N2-H2⋯O1 ii	0.916(17)	1.632(17)	2.5451(18)	174.0(17)
N2-H2⋯O2 ii	0.916(17)	2.59(2)	3.1463(19)	119.9(14)
*O3-H3⋯O2	0.91(3)	1.67(3)	2.5278(19)	155(2)
O7-H7A⋯O4 iii	0.85(3)	2.13(2)	2.9623(19)	168(2)
O7-H7B⋯O5 iv	0.81(3)	2.05(3)	2.841(2)	167(2)
*C6-H6⋯O4	0.95	2.59	2.951(2)	103
C8-H8A⋯O5 v	0.99	2.47	3.423(2)	161
C8-H8B⋯O7 vi	0.99	2.44	3.314(3)	147
C9-H9B⋯O3 vi	0.99	2.47	3.329(2)	145
C11-H11A⋯O2 vi	0.99	2.59	3.363(2)	135
C13-H13B⋯O7 vi	0.99	2.59	3.356(2)	134
(i) 1 − x, 1 − y, 2 − z; (ii) −x, 1 − y, 1 − z; (iii) 1 + x, y, −1 + z; (iv) 1 − x, −y, 1 − z; (v) 1 + x, 1 + y, z; (vi) 1 − x, 1 − y, 1 − z
6
*N1-H1⋯N2	0.930(18)	1.713(18)	2.5973(15)	157.6(17)
O1-H1A⋯O5 i	0.93(2)	1.63(2)	2.5468(13)	169(2)
*N3-H3⋯N4	0.93(2)	1.707(19)	2.5907(16)	158.8(17)
*O3-H3A⋯O2	0.87(2)	1.83(2)	2.6134(17)	148(2)
O7-H7⋯O11 ii	0.92(2)	1.66(2)	2.5714(13)	169(2)
*O9-H9⋯O8	0.89(2)	1.79(2)	2.6005(16)	149(2)
C25-H25B⋯O4 iii	0.98	2.52	3.4370(16)	157
C25-H25C⋯O2 iv	0.98	2.51	3.3061(18)	138
C26-H26A⋯O5 v	0.98	2.46	3.3977(18)	161
C27-H27C⋯O10	0.98	2.57	3.381(2)	140
C30-H30⋯O11 vi	0.95	2.49	3.4349(16)	173
C39-H39C⋯O8 iii	0.98	2.51	3.0482(17)	114
C40-H40A⋯O10 vi	0.98	2.39	3.3235(18)	159
C41-H41B⋯O12	0.98	2.50	3.1961(17)	128
C42-H42C⋯O12	0.98	2.58	3.2782(16)	128
(i) −x, ½ + y, ½ − z; (ii) 1 − x, −1/2 + y, ½ − z; (iii) x, −1 + y, z; (iv) x, −1 + y, z; (v) −x, −1/2 + y, ½ − z; (vi) 1 − x, 1 − y, −z

. It can be mentioned that nearly all available acceptors in all crystals, apart from 6, interact with all available donors. The two oxygen atoms in the sulfonic group play the role of bifurcated acceptors participating in the formation of O(N,C)-H⋯O interactions with anion, cation, and water molecules. A rare trifurcated (and tetrafurcated) acceptor is observed in 6 (Figure 3, Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8).

Overall, at first glance, novel salts exhibit similar self-assembly behavior. Nevertheless, a thorough examination revealed that the structures differ markedly as demonstrated in Figure 3, Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8. More specifically, compounds feature extensive H-bonding 3D-layered structures with significant π⋯π interactions in 2–4 with a Cg-Cg distance below 4 Å; and with the shortest distance—3.4111(12) Å in 4, and C-H⋯π in 5 and 6 (H⋯Cg distance below 3 Å) between the cations and anions, as demonstrated in Figure 3, Figure 4, Figure 5, Figure 6, Figure 7 and Figure 8. With respect to other weak π-based interactions, C-O⋯π (O⋯Cg distance below 4 Å) exist in 2, 4, and 5. It can be noted that the S-O⋯π [3.841(2) Å] inter-contact and C-Cl⋯π [Cl-Cg distance 3.6827(13) Å] halogen interaction were found in 2 (see Tables S2 and S3). In 2, a specific zig-zag layered structure is formed via alternating perpendicular separate anionic and cationic layers. Notably, water solvent molecules are significant contributors to building supramolecular architectures in all suitable cases (1–5). They play an important role as either a donor or acceptor of a bridge-linking moieties. The interplay of strong and weak H-bonding interactions and π-based inter-contacts gives rise to interesting supramolecular motifs at diverse levels of self-assembly. First of all, a specific intramolecular synthon, namely S(6), via O-H⋯O between the phenol OH group and a carboxyl O atom is observed in all crystals (Figure 9). It is key information from the crystal engineering point of view. This synthon can be employed in the pseudo-ring replacement strategy in the design of molecules. Another intramolecular H-bonding supramolecular motif via _(NH)N-H⋯N_(N) interactions in cationic moiety, but denoted by a similar descriptor S(6), is observed in crystal 6 (Table S4). In 2 and 4, a robust and very popular homosynthon R²₂(8) via O-H⋯O interaction is observed. Additionally, other centrosymmetric dimers, such as R²₂(16) in 2 by O-H⋯O, R²₂(12) in 1, R²₂(10) and R²₂(13) in 2 through C-H⋯O, were found. Moreover, heterosynthon R²₂(7) via O-H⋯O and C-H⋯O interactions is generated. Here, the OH group plays as role of either donor or acceptor simultaneously (Table S4). Moving forward, water molecules, linking ions, are involved in the formation of cyclic homosynthons as a donor and acceptor. Figure 9 illustrates the above supramolecular motifs taking into account anions. On the other hand, the protonated pyridine N atom of a cation forms diverse, interesting H-bonding supramolecular motifs with either COOH/COO⁻ or SO⁻ groups of anions or the water molecules as shown in Figure S1 (in Supplementary Materials). A library of supramolecular H-bonding synthons, including the first and second levels of the graph-set theory is provided (see Table S4). It is noteworthy that novel salts demonstrate remarkably varied supramolecular features arising mainly from different cationic polyamine species and their substituents.

The Full Interaction Maps (FIMs), related to statistical interaction data extracted from the CSD [62], helped us understand the effect of diverse substituents in the polyamines on supramolecular interactions and synthons formed by them. FIMs generated for all analyzed salts in the Mercury program [55] are presented in Figure 10. They illustrate zones around cations and anions where interactions are expected. It allowed us to estimate whether synthon preferences within the corresponding crystal lattices are satisfied. The FIMs of analyzed compounds 1–6 visualize the expected directions of the formation of either H-bonding or π-based interactions. Notably, nearly identical maps were obtained for the anions in all analyzed crystals, apart from 5. On the other hand, FIMs for cations are completely different. Areas of H-bonding donor probabilities are shown in blue while H-bonding acceptors are demonstrated in red. Aromatic/hydrophobic interactions are denoted in beige/light brown. It can be mentioned that the intensity of the color areas is compatible with the likelihood of the relevant inter-contacts occurring. It can be seen that cation 6 has the largest probability of being involved in hydrophobic interactions, while anion 5 can participate in forming synthons as acceptors only. The substituent effect on multifaceted classical and non-classical non-covalent interactions was thoroughly examined using complex Hirshfeld surfaces analysis, described in the next section.

3.2. Hirshfeld Surface Analysis

To gain a deep understanding of the crystal-packing behavior and the hierarchy of non-covalent interactions Hirshfeld surface analysis was performed. The 3D Hirshfeld surface maps for 1–6 were generated using either a standard surface solution of three-dimensional d_norm surfaces or shape index and curvedness properties (Figure 11). The normalized contact distance, called d_norm, is the sum of the distance of the point from the nearest nucleus within the Hirshfeld surface (d_i) and the distance of the point from the nearest nucleus outside the Hirshfeld surface (d_e) normalized via the van der Waals radius of the corresponding atom [66]. The surfaces were calculated for the 5-sulfosalicylate moiety, which is the same in all compounds to emphasize nuanced differences. The bright, larger red spots on the views of the d_norm surfaces indicate closer distances than the van der Waals radii. In particular, they display strong H-bonding interactions such as O-H⋯O and N-H⋯O between carboxyl and amino groups of anions and cations, respectively. The smaller spots signify weaker C-H⋯O interactions with neighboring moieties. The blue regions present longer inter-contacts than the van der Waals radii, while the white spots represent the close interactions equal to the sum of van der Waals radii. On the other hand, the convex blue spots on the shape index maps indicate hydrogen donor groups, while the concave red regions characterize acceptor groups. The π⋯π inter-contacts are represented via adjacent red and blue triangles on the shape index surfaces and as flat green areas around the rings, delineated by the blue outlines, on the curvature maps. Moving forward, orange-colored deformations of the Hirshfeld surfaces in crystals 5 and 6 indicate C-H⋯π interactions. For a better overview, the colored fragment patch surfaces were also generated to specify the nearest surrounding moiety [66], as shown in Figure 11. It can be used to calculate the number of moieties interacting with the main one.

3.2.1. Molecular Electrostatic Potential

In Figure 11, the electrostatic potential mapped onto the Hirshfeld surfaces is also presented. It visualizes molecular electrostatic complementarities verifying the acceptor’s and donors’ functions in the 3D supramolecular network. Blue areas indicate a positive electrostatic potential (H-bond donors), while red regions denote a negative electrostatic potential (acceptors) [64].

3.2.2. Fingerprints

The 2D fingerprint plots are constructed based on the distances d_e and d_i from the Hirshfeld surfaces. The shapes of the graphs are unique for each compound. They manifest differences and summarize the intricate quantitative information contained in molecular crystals 1–6 as illustrated in Figure 12. The percentage contribution of close interactions in these crystal structures is included in the same Figure. It is clear at first sight that the O⋯O/H⋯O interactions have the highest contribution in all crystals, at the level of 50%. They are characterized by long symmetrical/parallel ‘spikes’ in the fingerprint histograms. The absence of the second spike in 5 means that the anionic moiety only serves as an H-bonding acceptor, while the cationic is a donor. The H⋯H and C⋯H/H⋯C interactions are second and third contributors, representing an average of 21.5% and 11%, respectively. The latter interactions change from 4.9% in 2 to 23.5% in 6. The H⋯H contacts are visualized in the central region between the spikes, while the C⋯H/H⋯C interactions are visualized as ‘wings’ in the upper side of fingerprint plots. The C⋯C inter-contacts are significant to share in the 2–4 crystal structures, showing from 3.7% in 1 to 9.8% in 2. The C⋯O/O⋯C contacts, observed in 1–5, represent from 1.5% in 3 to 8.6% in 2. In addition, N⋯C/C⋯N contacts are observed in 1 (2.9%), 3 (3.5%), and 4 (5.3%), while N⋯H/H⋯N are reported in 1 (2.6%) and 4 (7.4%). A much smaller share falls on O⋯O (in 1, 2, and 5) and N⋯O/O⋯N (in 1 and 4), at a level of 3% and 1.5%, respectively (Table S5).

Enrichment ratios were calculated based on the Hirshfeld surface concept for all analyzed compounds to analyze the interactions with a high propensity to form contacts in the crystal packing. The obtained values are tabulated in

Table 3. Enrichment ratios for 1–6.

	1	2	3	4	5	6
H⋯H	0.756	0.83	0.79	0.686	0.73	0.62
O⋯H	3.131	1.607	1.791	1.804	1.53	1.64
C⋯H	0.962	0.407	0.42	0.512	0.81	1.64
N⋯H	0.719			1.138
O⋯O	0.246	0.247			0.27
O⋯C	0.471	1.043	0.202	0.382	0.57
O⋯N	0.57			0.418
C⋯C	1.967	6.53	4.3	3.279	2.99
C⋯N	4.03			3.223

and Table S6. Privileged interactions are as follows: O⋯H/H⋯O in all crystals, C⋯H/H⋯C—in 1 and 6, N⋯H/H⋯N in 4, C⋯C in nearly all structures (apart from 6), O⋯C/C⋯O in 2, C⋯N/N⋯C in 1 and 4. The highest value is obtained for the contacts O⋯H in 1, C⋯C in 1–5, and C⋯N in 1 and 4. However, C⋯C and C⋯N represent only ~5.5% and 4% of the contact surfaces, respectively. Surprisingly, H⋯H is one of the most abundant interactions in all structures (~20%), but they are disfavored in the crystal packing. The enrichment ratio values are below 1. O⋯N are disfavored, while O⋯O are impoverished.

The energy framework concept enables the visualization of strong interaction chains and an understanding of the distinct energy types. The three-dimensional energy frameworks for all six analyzed compounds are depicted in Figure 13. It emphasizes the neighboring moieties located in a radius of 3.8 Å from the analyzed molecule. Energy types are symbolized by different colors. In particular, red is for classical electrostatic (the coulombic), while green is for dispersion terms. In addition, the total energy is presented in blue. Notably, the cylinder/tube size (diameter) signifies the energy value; thicker cylinders mean higher energies. The tube thicknesses denote the relative interaction strengths. The calculated values of interaction energies, including the crystallographic symmetry operations, are summarized in

Table 4. The interaction energies via energy framework calculations. Energy values are given in kJ mol⁻¹. (R means the distance between molecular centroids; N is the number of interactions involving the central moiety).

	N	R	Eele	Epol	Edisp	Erep	Etot	Symmetry Operation
1
	1	5.98	7.1	0.0	−21.2	5.8	−7.1	−x, −y, −z
	1	5.90	7.1	−12.5	−21.2	5.8	−15.3
	1	6.55	−66.6	0.0	−16.5	9.3	−75.2	−x, −y, −z
	1	5.66	−66.6	−16.4	−16.5	9.3	−85.9
	1	7.85	15.5	−4.0	−12.9	1.3	2.6	−x, −y, −z
	1	7.64	−7.9	−0.7	−0.5	0.0	−9.0
	1	5.68	−7.9	−0.7	−0.5	0.0	−9.0
	1	5.80	−66.6	−16.4	−16.5	9.3	−85.9
	1	3.46	9.2	−1.4	−1.4	0.0	7.2
	1	6.38	7.1	−12.5	−21.2	5.8	−15.3
	1	6.93	15.5	−4.0	−12.9	1.3	2.6
	1	6.16	9.2	−1.4	−1.4	0.0	7.2
	1	8.58	−7.4	−6.1	−3.5	0.3	−14.5	−x, −y, −z
	1	7.34	−66.6	−16.4	−16.5	9.3	−85.9
			−218.9	−92.5	−162.7	57.2	−383.5
2
	1	5.13	28.7	−18.6	−43.8	21.2	−5.2	−x, −y, −z
	1	8.39	6.8	−4.2	−10.4	8.1	1.4	−x, −y, −z
	0	4.07	19.2	−37.6	−57.8	30.3	−32.4	−x, −y, −z
	1	6.89	26.6	−8.0	−10.9	2.3	13.8	x, y, z
	1	7.00	0.0	−4.2	0.0	0.0	−2.7
	0	6.96	35.9	−2.5	−2.2	0.0	32.9
	1	4.79	26.6	−8.0	−10.9	2.3	13.8
	0	6.09	−176.3	−61.8	−22.7	79.7	−175.6	−x, −y, −z
	0	5.65	8.7	−2.3	−1.8	0.0	5.7
	0	6.53	8.7	−2.3	−1.8	0.0	5.7
	1	8.65	28.7	−18.6	−43.8	21.2	−5.2
	1	7.90	28.7	−18.6	−43.8	21.2	−5.2
			42.3	−186.7	−249.9	186.3	−153
3
	1	9.13	8.5	−1.1	−5.6	2.9	5.2
	1	4.05	−93.4	−30.6	−11.1	55.8	−79.8
	1	3.65	−46.1	−18.2	−50.1	32.6	−77.5
	2	9.01	−23.9	−3.7	−2.3	0.1	−28.7	−x, y + 1/2, z
	2	8.48	−93.4	−30.6	−11.1	55.8	−79.8	x, y, z
	1	4.14	−12.0	−2.4	−1.9	0.0	−15.5
	1	6.21	0.0	−0.2	0.0	0.0	−0.1
	1	3.49	−55.6	−21.0	−48.5	28.3	−91.1
	1	8.13	1.4	−2.5	−8.0	13.5	3.6
	1	6.20	0.9	−8.3	−14.2	8.4	−10.4
	2	8.49	−25.3	−5.5	−3.8	0.2	−32.6	−x, y + 1/2, z
	1	5.82	−0.9	−5.1	−9.2	1.2	−11.5
	1	7.81	−11.2	−8.7	−12.9	15.0	−16.5
	1	7.58	−33.3	−14.8	−9.0	20.8	−34.8
			−384.3	−152.7	−187.7	234.6	−469.5
4
	1	7.40	−76.4	−14.8	−11.5	2.8	−95.6	−x, −y, −z
	1	8.81	6.5	−3.1	−8.9	5.7	1.3	−x, −y, −z
	1	9.38	0.0	−2.4	0.0	0.0	−1.6
	1	9.45	15.2	−2.7	−5.5	0.4	9.1	−x, −y, −z
	1	7.04	6.5	−3.1	−8.9	5.7	1.3
	1	8.27	−76.4	−14.8	−11.5	2.8	−95.6
	1	4.11	43.4	−2.9	−2.6	0.0	40.1
	1	7.88	15.2	−2.7	−5.5	0.4	9.1
	1	8.55	−10.7	−0.6	−0.3	0.0	−11.6
	1	7.63	−57.3	−6.7	−4.6	0.0	−66.8
	1	4.30	−57.3	−6.7	−4.6	0.0	−66.8
	1	3.97	43.4	−2.9	−2.6	0.0	40.1
			−148	−63.4	−66.5	17.8	−237
5
	1	4.81	44.8	−37.4	−40.7	16.9	−1.7	−x, −y, −z
	1	7.06	−3.7	−0.6	−1.3	0.0	−5.2
	1	5.38	10.1	−0.5	−0.7	0.0	9.3
	1	8.75	0.0	−6.4	0.0	0.0	−4.1	−x, −y, −z
	1	5.87	10.7	−1.4	−1.5	0.0	8.6
	1	6.64	−13.6	−9.5	−10.7	2.6	−27.6
	1	7.38	−39.5	−4.5	−7.6	0.5	−49.7	−x, −y, −z
	1	7.29	44.8	−37.4	−40.7	16.9	−1.7
	1	4.83	4.5	−0.2	−0.2	0.0	4.3
	1	6.01	−13.6	−9.5	−10.7	2.6	−27.6
	1	6.96	10.7	−1.4	−1.5	0.0	8.6
			55.2	−108.8	−115.6	39.5	−86.8
6
	2	7.91	−123.7	−40.9	−8.7	74	−100.5	−x, y + 1/2, −z + 1/2
	1	6.17	−16.6	−2.4	−1.7	0.0	−19.9
	2	9.34	−16.6	−2.4	−1.7	0.0	−19.9	x, −y + 1/2, z + 1/2
	1	8.06	28.9	−1.4	−0.5	0.0	28.1
	1	6.45	−123.7	−40.9	−8.7	74	−100.5
	1	6.94	0.0	−0.1	0.0	0.0	−0.1
	1	9.53	−16.6	−2.4	−1.7	0.0	−19.9
	1	9.60	0.0	−0.3	0.0	0.0	−0.2
	1	9.73	−123.7	−40.9	−8.7	74	−100.5
			−392	−131.7	−31.7	222	−333.4
	Energy model				k_ele	k_pol	k_disp	k_rep
	CE-HF⋯HF/3-21G electron densities				1.019	0.651	0.901	0.811
	CE-B3LYP⋯B3LYP/6-31G(d,p) electron densities				1.057	0.740	0.871	0.618

k—scale factor. Each form of energy should be multiplied by its relevant factor.

. It depicts the energy contributions of all components, such as electrostatic (E_ele), polarization (E_pol), dispersion (E_disp), and repulsion (E_rep), as well as total (E_tot) for various intermolecular interactions in the analyzed crystals. Details presented in Table 4 are pivotal for the calculations of lattice energy [71]. The results revealed several types of interactions between the center moiety and the neighboring moieties. The thorough analysis revealed that in 1, total interaction energy (E_tot = −85.9 kJ/mol) is associated with a symmetric pair of molecules distanced at R = 5.66, 5.80, and 7.34 Å, respectively. Similarly, in 2, a closer look at the obtained values of energies shows significant insights. As an example, in 1, the electrostatic, polarization, dispersion, and repulsion energies were calculated to be −218.9, −92.5, −162.7, and 57.2 kJ/mol, respectively (see Table 4). Further analysis indicated total lattice energies: −383.5 kJ/mol for 1, −153 kJ/mol for 2, −469.5 kJ/mol for 3, −237 kJ/mol for 4, −86.8 kJ/mol for 5, and −333.4 kJ/mol for 6. Thus, E_tot values show significant differences. The most thermodynamically stable salt is considered to be 3. Interestingly, 3 presents remarkable red cylinders that joined the molecular pairs forming a hexagon energy topology. It is noteworthy that overall, the electrostatic energy is clearly a dominant component in 1, 3, 4, and 6, while dispersive energy is in 2 and 5. This means that van der Waals forces, contributing to dispersion interactions, are significant in the supramolecular assembly in 2 and 5. In this regard, the interactions between the reference moiety and the symmetry-related molecule at −x, −y, and −z in 2 and 5 are the most important interactions, with E_tot = 175.6 and −49.7 kJ/mol, respectively.

4. Conclusions

In summary, a series of novel salts of heterocyclic polyamines with 5-sulfosalicylic acid, namely 2,4-diaminopyrimidin-1-ium 3-carboxy-4-hydroxybenzenesulfonate dihydrate (1), 2,4-diamino-6-chloropyrimidin-1-ium 3-carboxy-4-hydroxybenzenesulfonate hydrate (2), 2,6-diaminopyridin-1-ium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (3), 2,6-diamino-9H-purin-1-ium 3-carboxy-4-hydroxybenzenesulfonate monohydrate (4), and 8-(dimethylamino)-N,N-dimethylnaphthalen-1-aminium 3-carboxy-4-hydroxybenzenesulfonate (6) have been reported for the first time, to the best of our knowledge. We managed to successfully synthesize and crystallize new salts and determine their crystal structures by single-crystal X-ray diffraction. The hierarchical supramolecular features were characterized by diverse modern approaches, including mainly extended Hirshfeld surface concepts. In addition, in the analysis, we included 1,4-diazabicyclo[2.2.2]octane-1,4-dium 2-hydroxy-5-sulfonatobenzoate monohydrate (5) as a better re-determination of its previously published equivalent (CSD refcode: KAXAE). The new compounds 1, 2, 4, and 5 crystallize in the triclinic P$\overline{1}$ space group, while compounds 3 and 6 crystallize in the monoclinic P2₁ and P2₁/c space groups, respectively. Differences in the intermolecular interactions in 1–6 were seen on the Hirshfeld surface maps and fingerprint plots, as well as the energy frameworks. More specifically, O⋯H/H⋯O interactions are significant contributors (~ 50%). However, C⋯H/H⋯C (5–23%) N⋯H/H⋯N (below 7%) and C⋯C (below 10%) inter-contacts also govern the crystal packing of the studied structures. The latter represents π⋯π contacts with the shortest interplanar distance of 3.4111(12) Å in 4. The electrostatic interactions in most crystals (in 1, 3, 4, and 6), while the dispersion forces only in 2 and 5, were regarded as dominant in stabilizing the crystal packing. Notably, the presence of water molecules has a pivotal role in determining the crystal packing, as either a donor or acceptor, as well as, to some extent, the electrostatic properties. A library of hierarchical supramolecular H-bonding motifs is provided. A specific intramolecular synthon via O-H⋯O is observed in nearly all crystals. It can be employed in the pseudo-cyclic replacement strategy in the design of new molecules.