Recurrence of Carboxylic Acid−Pyridine Supramolecular Synthon in the Crystal Structures of Some Pyrazinecarboxylic Acids

X-ray crystal structures of pyrazinic acid 1 and isomeric methylpyrazine carboxylic acids 2−4 are analyzed to examine the occurrence of carboxylic acid−pyridine supramolecular synthon V in these heterocyclic acids. Synthon V, assembled by (carboxyl)O−H···N(pyridine) and (pyridine)C−H···O(carbonyl) hydrogen bonds, controls self-assembly in the crystal structures of pyridine and pyrazine monocarboxylic acids. The recurrence of acid−pyridine heterodimer V compared to the more common acid−acid homodimer I in the crystal structures of pyridine and pyrazine monocarboxylic acids is explained by energy computations in the RHF 6-31G* basis set. Both the O−H···N and the C−H···O hydrogen bonds in synthon V result from activated acidic donor and basic acceptor atoms in 1−4. Pyrazine 2,3- and 2,5-dicarboxylic acids 10 and 11 crystallize as dihydrates with a (carboxyl)O−H···O(water) hydrogen bond in synthon VII, a recurring pattern in the diacid structures. In summary, the carboxylic acid group forms an O−H···N hydrogen bond in pyrazine monocarboxylic acids and an O−H···O hydrogen bond in pyrazine dicarboxylic acids. This structural analysis correlates molecular features with supramolecular synthons in pyridine and pyrazine carboxylic acids for future crystal engineering strategies

Equivalence of NH₄⁺, NH₂NH₃⁺, and OHNH₃⁺ in Directing the Noncentrosymmetric Diamondoid Network of O−H···O^- Hydrogen Bonds in Dihydrogen Cyclohexane Tricarboxylate

The assembly of hexagonal and diamond network architectures from functionalized tectons of trigonal and tetrahedral symmetry, respectively, is an important activity in crystal engineering. We report a novel supramolecular transformation for the synthesis of diamond network structures from the trigonal molecule, 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H3CTA). Crystal structures of some salts of the trigonal anion, H2CTA-, with tetrahedral counterions is analyzed in H2CTA-·NH4+ 1, H2CTA-·MeNH3+ 2, H2CTA-·EtNH3+ 3, H2CTA-·NH2NH3+ 4, and H2CTA-·OHNH3+ 5. The trigonal anion functions as a tetrahedral self-complementary node in the presence of NH4+ counterion (salt 1) via two COOH donors and COO- as a double hydrogen-bond acceptor. The triply interpenetrated diamondoid network of O−H···O- hydrogen bonds in 1 is reproduced in isostructural 3D nets of 4 and 5 by substituting NH4+ by NH2NH3+ and OHNH3+ (Π = 0.025, 0.027). The SHG activity of noncentrosymmetric diamondoid solids 1, 4, and 5 (space group Cc) is comparable to that of the nonlinear optical (NLO) material potassium dihydrogen phosphate (KDP) (0.3 × urea). However, salts 2 and 3 (space groups P21/c and P1̄) have hexagonal and square grid layers of H2CTA- anions because the ammonium cation in these structures is devoid of the fourth strong hydrogen-bond donor group to extend crystal growth to the 3D diamond network. Thus, RNH3+ counterions may be used to control the anionic network of the H2CTA- molecule based on a tetrahedral node in 1, 4, and 5, a trigonal node in 2, and a square node in 3. The function of cyclohexane tricarboxylate as a four-connected node, shown for the first time in a trigonal molecule, is in contrast to the usual role of the trimesate anion as a three-connected node in molecular complexes

Equivalence of NH₄⁺, NH₂NH₃⁺, and OHNH₃⁺ in Directing the Noncentrosymmetric Diamondoid Network of O−H···O^- Hydrogen Bonds in Dihydrogen Cyclohexane Tricarboxylate

The assembly of hexagonal and diamond network architectures from functionalized tectons of trigonal and tetrahedral symmetry, respectively, is an important activity in crystal engineering. We report a novel supramolecular transformation for the synthesis of diamond network structures from the trigonal molecule, 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H3CTA). Crystal structures of some salts of the trigonal anion, H2CTA-, with tetrahedral counterions is analyzed in H2CTA-·NH4+ 1, H2CTA-·MeNH3+ 2, H2CTA-·EtNH3+ 3, H2CTA-·NH2NH3+ 4, and H2CTA-·OHNH3+ 5. The trigonal anion functions as a tetrahedral self-complementary node in the presence of NH4+ counterion (salt 1) via two COOH donors and COO- as a double hydrogen-bond acceptor. The triply interpenetrated diamondoid network of O−H···O- hydrogen bonds in 1 is reproduced in isostructural 3D nets of 4 and 5 by substituting NH4+ by NH2NH3+ and OHNH3+ (Π = 0.025, 0.027). The SHG activity of noncentrosymmetric diamondoid solids 1, 4, and 5 (space group Cc) is comparable to that of the nonlinear optical (NLO) material potassium dihydrogen phosphate (KDP) (0.3 × urea). However, salts 2 and 3 (space groups P21/c and P1̄) have hexagonal and square grid layers of H2CTA- anions because the ammonium cation in these structures is devoid of the fourth strong hydrogen-bond donor group to extend crystal growth to the 3D diamond network. Thus, RNH3+ counterions may be used to control the anionic network of the H2CTA- molecule based on a tetrahedral node in 1, 4, and 5, a trigonal node in 2, and a square node in 3. The function of cyclohexane tricarboxylate as a four-connected node, shown for the first time in a trigonal molecule, is in contrast to the usual role of the trimesate anion as a three-connected node in molecular complexes

Four-Fold Inclined Interpenetrated and Three-Fold Parallel Interpenetrated Hydrogen Bond Networks in 1,3,5-Cyclohexanetricarboxylic Acid Hydrate and Its Molecular Complex with 4,4‘-Bipyridine

Crystallization of 1,3,5-cyclohexanetricarboxylic acid (CTA) from EtOH affords the 1:1 hydrate, CTA·H2O, with 4-fold inclined interpenetrated (6,3) hydrogen-bonded networks. Crystallization of CTA with 4,4‘-bipyridine (bipy) furnishes the complex, CTA·bipy·H2O (2:3:1), that has 3-fold interweaving (6,3) networks with parallel interpenetration. The striking similarity of these hydrogen bond networks to those found in the crystal structure of trimesic acid and its complex with bipy suggests that such interpenetrated networks may be engineered using retrosynthetic strategies

Four-Fold Inclined Interpenetrated and Three-Fold Parallel Interpenetrated Hydrogen Bond Networks in 1,3,5-Cyclohexanetricarboxylic Acid Hydrate and Its Molecular Complex with 4,4‘-Bipyridine

Crystallization of 1,3,5-cyclohexanetricarboxylic acid (CTA) from EtOH affords the 1:1 hydrate, CTA·H2O, with 4-fold inclined interpenetrated (6,3) hydrogen-bonded networks. Crystallization of CTA with 4,4‘-bipyridine (bipy) furnishes the complex, CTA·bipy·H2O (2:3:1), that has 3-fold interweaving (6,3) networks with parallel interpenetration. The striking similarity of these hydrogen bond networks to those found in the crystal structure of trimesic acid and its complex with bipy suggests that such interpenetrated networks may be engineered using retrosynthetic strategies

Equivalence of NH₄⁺, NH₂NH₃⁺, and OHNH₃⁺ in Directing the Noncentrosymmetric Diamondoid Network of O−H···O^- Hydrogen Bonds in Dihydrogen Cyclohexane Tricarboxylate

The assembly of hexagonal and diamond network architectures from functionalized tectons of trigonal and tetrahedral symmetry, respectively, is an important activity in crystal engineering. We report a novel supramolecular transformation for the synthesis of diamond network structures from the trigonal molecule, 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H3CTA). Crystal structures of some salts of the trigonal anion, H2CTA-, with tetrahedral counterions is analyzed in H2CTA-·NH4+ 1, H2CTA-·MeNH3+ 2, H2CTA-·EtNH3+ 3, H2CTA-·NH2NH3+ 4, and H2CTA-·OHNH3+ 5. The trigonal anion functions as a tetrahedral self-complementary node in the presence of NH4+ counterion (salt 1) via two COOH donors and COO- as a double hydrogen-bond acceptor. The triply interpenetrated diamondoid network of O−H···O- hydrogen bonds in 1 is reproduced in isostructural 3D nets of 4 and 5 by substituting NH4+ by NH2NH3+ and OHNH3+ (Π = 0.025, 0.027). The SHG activity of noncentrosymmetric diamondoid solids 1, 4, and 5 (space group Cc) is comparable to that of the nonlinear optical (NLO) material potassium dihydrogen phosphate (KDP) (0.3 × urea). However, salts 2 and 3 (space groups P21/c and P1̄) have hexagonal and square grid layers of H2CTA- anions because the ammonium cation in these structures is devoid of the fourth strong hydrogen-bond donor group to extend crystal growth to the 3D diamond network. Thus, RNH3+ counterions may be used to control the anionic network of the H2CTA- molecule based on a tetrahedral node in 1, 4, and 5, a trigonal node in 2, and a square node in 3. The function of cyclohexane tricarboxylate as a four-connected node, shown for the first time in a trigonal molecule, is in contrast to the usual role of the trimesate anion as a three-connected node in molecular complexes

An Acetic Acid Solvate of Trimesic Acid That Exhibits Triple Inclined Interpenetration and Mixed Supramolecular Homosynthons

Triple inclined interpenetration between one-dimensional truncated and two-dimensional honeycomb networks occurs in the acetic acid solvate of trimesic acid (1:2 ratio of acetic acid to trimesic acid); the existence of mixed supramolecular homosynthons in this structure offers insights into crystal engineering involving carboxylic acids

Equivalence of NH₄⁺, NH₂NH₃⁺, and OHNH₃⁺ in Directing the Noncentrosymmetric Diamondoid Network of O−H···O^- Hydrogen Bonds in Dihydrogen Cyclohexane Tricarboxylate

The assembly of hexagonal and diamond network architectures from functionalized tectons of trigonal and tetrahedral symmetry, respectively, is an important activity in crystal engineering. We report a novel supramolecular transformation for the synthesis of diamond network structures from the trigonal molecule, 1,3-cis,5-cis-cyclohexanetricarboxylic acid (H3CTA). Crystal structures of some salts of the trigonal anion, H2CTA-, with tetrahedral counterions is analyzed in H2CTA-·NH4+ 1, H2CTA-·MeNH3+ 2, H2CTA-·EtNH3+ 3, H2CTA-·NH2NH3+ 4, and H2CTA-·OHNH3+ 5. The trigonal anion functions as a tetrahedral self-complementary node in the presence of NH4+ counterion (salt 1) via two COOH donors and COO- as a double hydrogen-bond acceptor. The triply interpenetrated diamondoid network of O−H···O- hydrogen bonds in 1 is reproduced in isostructural 3D nets of 4 and 5 by substituting NH4+ by NH2NH3+ and OHNH3+ (Π = 0.025, 0.027). The SHG activity of noncentrosymmetric diamondoid solids 1, 4, and 5 (space group Cc) is comparable to that of the nonlinear optical (NLO) material potassium dihydrogen phosphate (KDP) (0.3 × urea). However, salts 2 and 3 (space groups P21/c and P1̄) have hexagonal and square grid layers of H2CTA- anions because the ammonium cation in these structures is devoid of the fourth strong hydrogen-bond donor group to extend crystal growth to the 3D diamond network. Thus, RNH3+ counterions may be used to control the anionic network of the H2CTA- molecule based on a tetrahedral node in 1, 4, and 5, a trigonal node in 2, and a square node in 3. The function of cyclohexane tricarboxylate as a four-connected node, shown for the first time in a trigonal molecule, is in contrast to the usual role of the trimesate anion as a three-connected node in molecular complexes

Molecular Complexes of Homologous Alkanedicarboxylic Acids with Isonicotinamide: X-ray Crystal Structures, Hydrogen Bond Synthons, and Melting Point Alternation

Crystallization of α,ω-alkanedicarboxylic acids (HOOC−(CH2)n-2−COOH, n = 2−6) with isonicotinamide (IN) is carried out in 1:2 and 1:1 stoichiometry. Five cocrystals of (diacid)·(IN)2 composition (diacid = oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) are characterized by X-ray diffraction at 153(2) K. Tapes of acid−pyridine O−H···N and amide−amide N−H···O hydrogen bond synthons stabilize these five crystal structures as predicted by the hierarchic model:  the best donor (COOH) and best acceptor group (pyridine N) hydrogen bond as acid−pyridine and the second best donor−acceptor group (CONH2) aggregates as an amide dimer. Glutaric acid and adipic acid cocrystallize in 1:1 stoichiometry also, (diacid)·(IN), with acid−pyridine and acid−amide hydrogen bonds. Synthon energy calculations (ΔEsynthon, RHF/6-31G**) explain the observed hydrogen bond preferences in 1:2 (five examples) and 1:1 (two examples) cocrystals. The acid−pyridine hydrogen bond is favored over the acid−amide dimer for strong carboxylic acids because the difference between ΔEacid-pyridine and ΔEacid-amide (−2.21 kcal mol-1) is greater than the difference for weak acids (−0.77 kcal mol-1), which cocrystallize with both of these hydrogen bond synthons. We suggest ΔEsynthon as a semiquantitative parameter to rank hydrogen bond preferences and better understand supramolecular organization in the multifunctional acid−IN system. Melting point alternation in five homologous (diacid)·(IN)2 cocrystals is correlated with changes in crystal density and packing fraction

Molecular Complexes of Homologous Alkanedicarboxylic Acids with Isonicotinamide: X-ray Crystal Structures, Hydrogen Bond Synthons, and Melting Point Alternation

Crystallization of α,ω-alkanedicarboxylic acids (HOOC−(CH2)n-2−COOH, n = 2−6) with isonicotinamide (IN) is carried out in 1:2 and 1:1 stoichiometry. Five cocrystals of (diacid)·(IN)2 composition (diacid = oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) are characterized by X-ray diffraction at 153(2) K. Tapes of acid−pyridine O−H···N and amide−amide N−H···O hydrogen bond synthons stabilize these five crystal structures as predicted by the hierarchic model:  the best donor (COOH) and best acceptor group (pyridine N) hydrogen bond as acid−pyridine and the second best donor−acceptor group (CONH2) aggregates as an amide dimer. Glutaric acid and adipic acid cocrystallize in 1:1 stoichiometry also, (diacid)·(IN), with acid−pyridine and acid−amide hydrogen bonds. Synthon energy calculations (ΔEsynthon, RHF/6-31G**) explain the observed hydrogen bond preferences in 1:2 (five examples) and 1:1 (two examples) cocrystals. The acid−pyridine hydrogen bond is favored over the acid−amide dimer for strong carboxylic acids because the difference between ΔEacid-pyridine and ΔEacid-amide (−2.21 kcal mol-1) is greater than the difference for weak acids (−0.77 kcal mol-1), which cocrystallize with both of these hydrogen bond synthons. We suggest ΔEsynthon as a semiquantitative parameter to rank hydrogen bond preferences and better understand supramolecular organization in the multifunctional acid−IN system. Melting point alternation in five homologous (diacid)·(IN)2 cocrystals is correlated with changes in crystal density and packing fraction