Supramolecular hydrogen-bonding patterns in salts of the antifolate drugs trimethoprim and pyrimethamine

Nine salts of the antifolate drugs trimethoprim and pyrimethamine, namely, trimethoprimium [or 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium] 2,5-dichlorothiophene-3-carboxylate monohydrate (TMPDCTPC, 1:1), C₁₄H₁₉N₄O₃⁺·C₅HCl₂O₂S^-, (I), trimethoprimium 3-bromothiophene-2-carboxylate monohydrate, (TMPBTPC, 1:1:1), C₁₄H₁₉N₄O₃⁺·C₅H₂BrO₂S^-·H₂O, (II), trimethoprimium 3-chlorothiophene-2-carboxylate monohydrate (TMPCTPC, 1:1:1), C₁₄H₁₉N₄O₃⁺·C₅H₂ClO₂S^-·H₂O, (III), trimethoprimium 5-methylthiophene-2-carboxylate monohydrate (TMPMTPC, 1:1:1), C₁₄H₁₉N₄O₃⁺·C₆H₅O₂S^-·H₂O, (IV), trimethoprimium anthracene-9-carboxylate sesquihydrate (TMPAC, 2:2:3), C₁₄H₁₉N₄O₃⁺·C₁₅H₉O₂^-·1.5H₂O, (V), pyrimethaminium [or 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium] 2,5-dichlorothiophene-3-carboxylate (PMNDCTPC, 1:1), C₁₂H₁₄ClN₄⁺·C₅HCl₂O₂S^-, (VI), pyrimethaminium 5-bromothiophene-2-carboxylate (PMNBTPC, 1:1), C₁₂H₁₄ClN₄⁺·C₅H₂BrO₂S^-, (VII), pyrimethaminium anthracene-9-carboxylate ethanol monosolvate monohydrate (PMNAC, 1:1:1:1), C₁₂H₁₄ClN₄⁺·C₁₅H₉O₂^-·C₂H₅OH·H₂O, (VIII), and bis(pyrimethaminium) naphthalene-1,5-disulfonate (PMNNSA, 2:1), 2C₁₂H₁₄ClN₄⁺·C₁₀H₆O₆S₂^2-, (IX), have been prepared and characterized by single-crystal X-ray diffraction. In all the crystal structures, the pyrimidine N1 atom is protonated. In salts (I)-(III) and (VI)-(IX), the 2-aminopyrimidinium cation interacts with the corresponding anion via a pair of N-H...O hydrogen bonds, generating the robust R₂²(8) supramolecular heterosynthon. In salt (IV), instead of forming the R₂²(8) heterosynthon, the carboxylate group bridges two pyrimidinium cations via N-H...O hydrogen bonds. In salt (V), one of the carboxylate O atoms bridges the N1-H group and a 2-amino H atom of the pyrimidinium cation to form a smaller R₂¹(6) ring instead of the R₂²(8) ring. In salt (IX), the sulfonate O atoms mimic the role of carboxylate O atoms in forming an R₂²(8) ring motif. In salts (II)-(IX), the pyrimidinium cation forms base pairs via a pair of N-H...N hydrogen bonds, generating a ring motif [R₂²(8) homosynthon]. Compounds (II) and (III) are isomorphous. The quadruple DDAA (D = hydrogen-bond donor and A = hydrogen-bond acceptor) array is observed in (I). In salts (II)-(IV) and (VI)-(IX), quadruple DADA arrays are present. In salts (VI) and (VII), both DADA and DDAA arrays co-exist. The crystal structures are further stabilized by π-π stacking interactions [in (I), (V) and (VII)-(IX)], C-H...π interactions [in (IV)-(V) and (VII)-(IX)], C-Br...π interactions [in (II)] and C-Cl...π interactions [in (I), (III) and (VI)]. Cl...O and Cl...Cl halogen-bond interactions are present in (I) and (VI), with distances and angles of 3.0020 (18) and 3.5159 (16) Å, and 165.56 (10) and 154.81 (11)°, respectively.

Supramolecular architectures in cytosinium 6-chloronicotinate monohydrate and 5-bromo-6-methylisocytosinium hydrogen sulfate

Aminopyrimidine derivatives are biologically important as they are components of nucleic acids and drugs. The crystals of two new salts, namely cytosinium 6-chloronicotinate monohydrate, C₄H₆N₃O⁺·C₆H₃ClNO₂^-·H₂O, (I), and 5-bromo-6-methylisocytosinium hydrogen sulfate (or 2-amino-5-bromo-4-oxo-6-methylpyrimidinium hydrogen sulfate), C₅H₇BrN₃O⁺·HSO₄^-, (II), have been prepared and characterized by single-crystal X-ray diffraction. The pyrimidine ring of both compounds is protonated at the imine N atom. In hydrated salt (I), the primary R₂²(8) ring motif (supramolecular heterosynthon) is formed via a pair of N-H...O(carboxylate) hydrogen bonds. The cations, anions and water molecule are hydrogen bonded through N-H...O, N-H...N, O-H...O and C-H...O hydrogen bonds, forming R₂²(8), R₃²(7) and R₅⁵(21) motifs, leading to a hydrogen-bonded supramolecular sheet structure. The supramolecular double sheet structure is formed via water-carboxylate O-H...O hydrogen bonds and π-π interactions between the anions and the cations. In salt (II), the hydrogen sulfate ions are linked via O-H...O hydrogen bonds to generate zigzag chains. The aminopyrimidinium cations are embedded between these zigzag chains. Each hydrogen sulfate ion bridges two cations via pairs of N-H...O hydrogen bonds and vice versa, generating two R₂²(8) ring motifs (supramolecular heterosynthon). The cations also interact with one another via halogen-halogen (Br...Br) and halogen-oxygen (Br...O) interactions.

Supra-molecular inter-actions in 2,6-di-amino-4-chloro-pyrimidin-1-ium 5-chloro-salicylate and bis-(2,6-di-amino-4-chloro-pyrimidin-1-ium) naphthalene-1,5-di-sulfonate

The crystals of two new salts, 2,6-di-amino-4-chloro-pyrimidin-1-ium 5-chloro-salicylate, C4H6ClN4+·C7H4ClO3-, (I), and bis-(2,6-di-amino-4-chloro-pyrimidin-1-ium) naphthalene-1,5-di-sulfonate, 2C4H6ClN4+·C10H6O6S22-, (II), have been synthesized and characterized by single-crystal X-ray diffraction. In both compounds, the N atom of the pyrimidine group in between the amino substituents is protonated and the pyrimidinium cation forms a pair of N-H⋯O hydrogen bonds with the carboxyl-ate/sulfonate ion, leading to a robust R22(8) motif (supra-molecular heterosynthon). In compound (I), a self-complementary base pairing involving the other pyrimidinium ring nitro-gen atom and one of the amino groups via a pair of N-H⋯N hydrogen bonds [R22(8) homosynthon] is also present. In compound (II), the crystallographic inversion centre coincides with the inversion centre of the naphthalene-1,5-di-sulfonate ion and all the sulfonate O atoms are hydrogen-bond acceptors, generating fused-ring motifs and a quadruple DDAA array. A halogen-bond (Cl⋯Cl) inter-action is present in (I) with a distance and angle of 3.3505 (12) Å and 151.37 (10)°, respectively. In addition, a C-Cl⋯π inter-action and a π-π inter-action in (I) and a π-π inter-action in (II) further stabilize these crystal structures.

Bis(picolinato) complexes of vanadium and zinc as potential antidiabetic agents: synthesis, structural elucidation and in vitro insulin-mimetic activity study

The studied vanadium(iv), vanadium(v) and zinc(ii) complexes show inhibition of the free fatty acid release from rat adipocytes.

Extending the family of quinolone antibacterials to new copper derivatives: self-assembly, structural and topological features, catalytic and biological activity

New copper(ii) compounds with quinolone pefloxacin were synthesized and fully characterized; they exhibit notable catalytic activity and promising biological profiles.

A 26-Membered Macrocycle Obtained by a Double Diels-Alder Cycloaddition Between Two 2H-Pyran-2-one Rings and Two 1,1'-(Hexane-1,6-diyl)bis (1H-pyrrole-2,5-dione)s

With the application of a double dienophile 1,1'-(hexane-1,6-diyl)bis(1H-pyrrole-2,5-dione) for a [4+2] cycloaddition with a substituted 2H-pyran-2-one a novel 26-membered tetraaza heteromacrocyclic system 3 was prepared via a direct method under solvent-free conditions with microwave irradiation. The macrocycle prepared is composed of two units of the dienophile and two of the diene. The structure of the macrocycle was characterized on the basis of IR, 1H and 13C NMR and mass spectroscopy, as well as by the elemental analysis and melting point determination. With X-ray diffraction of a single crystal of the macrocycle we have determined that the two acetyl groups (attached to the bridging double bond of the bicyclo[2.2.2]octene fragments) are oriented towards each other (and also towards the inside of the cavity of the macrocycle), therefore, mostly filling it completely.

Copper(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionate) complexes with pyridin-2-one, 3-hydroxypyridine and 3-hydroxypyridin-2-one ligands: molecular structures and hydrogen-bonded networks

Copper(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionate) complexes with pyridin-2-one (pyon), 3-hydroxypyridine (hpy) and 3-hydroxypyridin-2-one (hpyon) were prepared and the solid-state structures of (pyridin-2-one-κO)bis(4,4,4-trifluoro-3-oxo-1-phenylbutan-1-olato-κ²O,O')copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)] or [Cu(tfpb-κ²O,O')₂(pyon-κO)], (I), bis(pyridin-3-ol-κO)bis(4,4,4-trifluoro-3-oxo-1-phenylbutan-1-olato-κ²O,O')copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO)₂] or [Cu(tfpb-κ²O,O')₂(hpy-κO)₂], (II), and bis(3-hydroxypyridin-2-one-κO)bis(4,4,4-trifluoro-3-oxo-1-phenylbutan-1-olato-κ²O,O')copper(II), [Cu(C₁₀H₆F₃O₂)₂(C₅H₅NO₂)₂] or [Cu(tfpb-κ²O,O')₂(hpyon-κO)₂], (III), were determined by single-crystal X-ray analysis. The coordination of the metal centre is square pyramidal and displays a rare example of a mutual cis arrangement of the β-diketonate ligands in (I) and a trans-octahedral arrangement in (II) and (III). Complex (II) presents the first crystallographic evidence of κO-monodentate hpy ligation to the transition metal enabling the pyridine N atom to participate in a two-dimensional hydrogen-bonded network through O-H...N interactions, forming a graph-set motif R₂²(7) through a C-H...O interaction. Complex (III) presents the first crystallographic evidence of monodentate coordination of the neutral hpyon ligand to a metal centre and a two-dimensional hydrogen-bonded network is formed through N-H...O interactions facilitated by C-H...O interactions, forming the graph-set motifs R₂²(8) and R₂²(7).

Supramolecular architectures in the salt trimethoprimium ferrocene-1-carboxylate and the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1)

In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium ferrocene-1-carboxylate], (C₁₄H₁₉N₄O₃)[Fe(C₅H₅)(C₆H₄O₂)], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N-H...O hydrogen bonds, generating a robust R₂²(8) ring motif (heterosynthon). However, in the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1), [Fe(C₅H₅)(C₆H₅O₂)]·C₆H₈ClN₃, (II), the carboxyl-aminopyrimidine interaction [R₂²(8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O-H...N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N-H...N hydrogen bonds, generating an R₂²(8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site-occupation ratio of 0.573 (10):0.427 (10). In this study, the two five-membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 36.13-37.53° for (I) and 22.58-23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C...Cg...Cg...C pseudo-torsion angles, which are in the range 79.26-80.94°. Both crystal structures are further stabilized by weak π-π interactions.

Supra-molecular hydrogen-bonding patterns in a 1:1 co-crystal of the N(7)-H tautomeric form of N6-benzoyl-adenine with 4-hy-droxy-benzoic acid

The asymmetric unit of the title co-crystal, C12H9N5O·C7H6O3, contains one mol-ecule of N6-benzoyl-adenine (BA) and one mol-ecule of 4-hy-droxy-benzoic acid (HBA). The N6-benzoyl-adenine (BA) has an N(7)-H tautomeric form with nonprotonated N-1 and N-3 atoms. This tautomeric form is stabilized by a typical intra-molecular N-H⋯O hydrogen bond between the carbonyl (C=O) group and the N(7)-H hydrogen on the Hoogsteen face of the purine ring, forming a graph-set S(7) ring motif. The primary robust R22(8) ring motif is formed in the Watson-Crick face via N-H⋯O and O-H⋯N hydrogen bonds (involving N1, N6-H and the carboxyl group of HBA). Weak inter-actions, such as, C-H⋯π and π-π are also observed in this crystal structure.

Vanadium and zinc complexes of 5-cyanopicolinate and pyrazine derivatives: synthesis, structural elucidation and in vitro insulino-mimetic activity study

Inhibition of free fatty acid release from rat adipocytes was observed for vanadium(iv), vanadium(v) and zinc(ii) complexes.

CuII and ZnII β-diketonate coordination polymers based on pyrimidin-2-amine, pyrazine and 1,2-bis(4-pyridyl)ethane

Copper(II) and zinc(II) bis(4,4,4-trifluoro-1-phenylbutane-1,3-dionato) compounds with pyrimidin-2-amine (pyr2a), pyrazine (pyz) and 1,2-bis(4-pyridyl)ethane (dpet) were prepared and solid-state structures of coordination polymers [M(tfpb)₂(pyr2a)]_∞ [M = Cu (1), Zn (2); tfpb = 4,4,4-trifluoro-1-phenylbutane-1,3-dionate], [M(tfpb)₂(pyz)]_∞ [M = Cu (3), Zn (4a, 4b)] and [Cu(tfpb)₂(dpet)]_∞ (5), respectively, were determined by single-crystal X-ray analysis. The coordination of metal centers in all compounds is octahedral with nitrogen ligands occupying the axial positions. Compound (1) crystallizes in the triclinic space group P\bar 1, whereas (2) crystallizes in the monoclinic space group P2/n. Differences are due to the different orientation of adjacent M(tfpb)₂ units, whereas the orientation of pyrimidin-2-amine is the same in both compounds. Polymeric chains in (1) and (2) contain intramolecular N-H...O hydrogen bonding between amino and carbonyl groups. Room-temperature structures (3) and (4a) are isomorphous adopting the monoclinic space group C2/m; however, on cooling crystals (4a) to 150 K a single-crystal-to-single-crystal transformation to (4b) possessing the triclinic space group P\bar 1 was observed. Compound (5) crystallizes in the triclinic space group P\bar 1 and contains a parallel aggregation of chains in contrast to the known structure of the non-fluorinated benzoylacetonato ligand, where chains aggregate in a perpendicular fashion. In the compounds studied intramolecular C-H...O and/or C-H...F interactions are present. The neighboring chains are linked by π...π interactions and in some compounds also by C-H...π interactions [(1), (4b), (5)].

Synthesis and Structural Evaluation of 5-Methyl-6-acetyl Substituted Indole and Gramine

The synthesis and crystal structures of 1-(5-methyl-1H-indol-6-yl)ethan-1-one (7), C11H11NO, and 1-3-[(dimethylamino) methyl]-5-methyl-1H-indol-6-ylethan-1-one (8), C14H18N2O, are reported. The synthesis is based on the Diels-Alder cycloaddition of a substituted 2H-pyran-2-one derivative, followed by an acid-catalyzed cyclization and concomitant deprotection (the last two steps were carried out as a one-pot domino process) yielding substituted indole 7, which was further derivatized via Mannich reaction to the gramine derivative 8. Both structures 7 and 8 were determined on the basis of IR, 1H NMR and mass spectroscopy, as well as by the elemental analysis and melting point determination. According to the single-crystal X-Ray diffraction analysis, the structure 7 has a single unique molecule in the asymmetric unit whereas the structure 8 contains four unique molecules in the asymmetric unit. Molecules 7 are linked via N-H···O hydrogen bonds between the secondary amine group and carbonyl moiety of the acetyl group of adjacent molecules, whereas molecules 8 are linked via N-H···N hydrogen bonds between the secondary and tertiary amine groups of adjacent molecules. Both structures are further stabilized by weak C-H···O, C-H···π and π···π interactions.

Regioselective Hydrolysis and Transesterification of Dimethyl 3-Benzamidophthalates Assisted by a Neighboring Amide Group

An efficient, highly regioselective hydrolysis and transesterification of dimethyl 3-benzamidophthalates into the corresponding carboxylic acid monoesters and mixed esters (including tert-butyl esters) under basic conditions is presented. The selectivity is governed by the neighboring 3-benzamido moiety's participation and by the nature of the solvent. In alcohols the reaction occurred exclusively at the ortho-position to the benzamido functionality, in pyridine or acetonitrile at both ester groups. An insight into the mechanistic pathway was obtained from a (1)H NMR study in perdeuteromethanol.

Supra-molecular architecture in a co-crystal of the N(7)-H tautomeric form of N (6)-benzoyl-adenine with adipic acid (1/0.5)

The asymmetric unit of the title co-crystal, C12H9N5O·0.5C6H10O4, consists of one mol-ecule of N (6)-benzoyl-adenine (BA) and one half-mol-ecule of adipic acid (AA), the other half being generated by inversion symmetry. The dihedral angle between the adenine and phenyl ring planes is 26.71 (7)°. The N (6)-benzoyl-adenine mol-ecule crystallizes in the N(7)-H tautomeric form with three non-protonated N atoms. This tautomeric form is stabilized by intra-molecular N-H⋯O hydrogen bonding between the carbonyl (C=O) group and the N(7)-H hydrogen atom on the Hoogsteen face of the purine ring, forming an S(7) ring motif. The two carboxyl groups of adipic acid inter-act with the Watson-Crick face of the BA mol-ecules through O-H⋯N and N-H⋯O hydrogen bonds, generating an R 2 (2)(8) ring motif. The latter units are linked by N-H⋯N hydrogen bonds, forming layers parallel to (10-5). A weak C-H⋯O hydrogen bond is also present, linking adipic acid mol-ecules in neighbouring layers, enclosing R (2) 2(10) ring motifs and forming a three-dimensional structure. C=O⋯π and C-H⋯π inter-actions are also present in the structure.

Supramolecular architectures in Co(II) and Cu(II) complexes with thiophene-2-carboxylate and 2-amino-4,6-dimethoxypyrimidine ligands

The coordination chemistry of mixed-ligand complexes continues to be an active area of research since these compounds have a wide range of applications. Many coordination polymers and metal-organic framworks are emerging as novel functional materials. Aminopyrimidine and its derivatives are flexible ligands with versatile binding and coordination modes which have been proven to be useful in the construction of organic-inorganic hybrid materials and coordination polymers. Thiophenecarboxylic acid, its derivatives and their complexes exhibit pharmacological properties. Cobalt(II) and copper(II) complexes of thiophenecarboxylate have many biological applications, for example, as antifungal and antitumor agents. Two new cobalt(II) and copper(II) complexes incorporating thiophene-2-carboxylate (2-TPC) and 2-amino-4,6-dimethoxypyrimidine (OMP) ligands have been synthesized and characterized by X-ray diffraction studies, namely (2-amino-4,6-dimethoxypyrimidine-κN)aquachlorido(thiophene-2-carboxylato-κO)cobalt(II) monohydrate, [Co(C5H3O2S)Cl(C6H9N3O2)(H2O)]·H2O, (I), and catena-poly[copper(II)-tetrakis(μ-thiophene-2-carboxylato-κ(2)O:O')-copper(II)-(μ-2-amino-4,6-dimethoxypyrimidine-κ(2)N(1):N(3))], [Cu2(C5H3O2S)4(C6H9N3O2)]n, (II). In (I), the Co(II) ion has a distorted tetrahedral coordination environment involving one O atom from a monodentate 2-TPC ligand, one N atom from an OMP ligand, one chloride ligand and one O atom of a water molecule. An additional water molecule is present in the asymmetric unit. The amino group of the coordinated OMP molecule and the coordinated carboxylate O atom of the 2-TPC ligand form an interligand N-H...O hydrogen bond, generating an S(6) ring motif. The pyrimidine molecules also form a base pair [R2(2)(8) motif] via a pair of N-H...N hydrogen bonds. These interactions, together with O-H...O and O-H...Cl hydrogen bonds and π-π stacking interactions, generate a three-dimensional supramolecular architecture. The one-dimensional coordination polymer (II) contains the classical paddle-wheel [Cu2(CH3COO)4(H2O)2] unit, where each carboxylate group of four 2-TPC ligands bridges two square-pyramidally coordinated Cu(II) ions and the apically coordinated OMP ligands bridge the dinuclear copper units. Each dinuclear copper unit has a crystallographic inversion centre, whereas the bridging OMP ligand has crystallographic twofold symmetry. The one-dimensional polymeric chains self-assemble via N-H...O, π-π and C-H...π interactions, generating a three-dimensional supramolecular architecture.

Supra-molecular inter-actions in a 1:1 co-crystal of acridine and 3-chloro-thio-phene-2-carb-oxy-lic acid

In the title co-crystal, C5H3ClO2S·C13H9N, the components inter-act with each other via an O-H⋯N hydrogen bond. Acridine-acridine stacking, thio-phene-thio-phene stacking and acridine-thio-phene C-H⋯π inter-actions also occur in the crystal.

Supra-molecular hydrogen-bonding patterns in the N(9)-H protonated and N(7)-H tautomeric form of an N(6) -benzoyl-adenine salt: N (6)-benzoyl-adeninium nitrate

In the title molecular salt, C12H10N5O(+)·NO3 (-), the adenine unit has an N (9)-protonated N(7)-H tautomeric form with non-protonated N(1) and N(3) atoms. The dihedral angle between the adenine ring system and the phenyl ring is 51.10 (10)°. The typical intra-molecular N(7)-H⋯O hydrogen bond with an S(7) graph-set motif is also present. The benzoyl-adeninium cations also form base pairs through N-H⋯O and C-H⋯N hydrogen bonds involving the Watson-Crick face of the adenine ring and the C and O atoms of the benzoyl ring of an adjacent cation, forming a supra-molecular ribbon with R 2 (2)(9) rings. Benzoyl-adeninum cations are also bridged by one of the oxygen atoms of the nitrate anion, which acts as a double acceptor, forming a pair of N-H⋯O hydrogen bonds to generate a second ribbon motif. These ribbons together with π-π stacking inter-actions between the phenyl ring and the five- and six-membered adenine rings of adjacent mol-ecules generate a three-dimensional supra-molecular architecture.

Structure and biological activities of metal complexes of flumequine

Co(ii)–flumequine complexes were characterized and their biological activity was evaluated in regard to DNA- and albumin-binding and antimicrobial and antiproliferative activity.

Supramolecular hydrogen-bonding patterns in two cocrystals of the N(7)–H tautomeric form ofN6-benzoyladenine:N6-benzoyladenine–3-hydroxypyridinium-2-carboxylate (1/1) andN6-benzoyladenine–DL-tartaric acid (1/1)

Two novel cocrystals of the N(7)—H tautomeric form ofN6-benzoyladenine (BA), namelyN6-benzoyladenine–3-hydroxypyridinium-2-carboxylate (3HPA) (1/1), C12H9N5O·C6H5NO3, (I), andN6-benzoyladenine–DL-tartaric acid (TA) (1/1), C12H9N5O·C4H6O6, (II), are reported. In both cocrystals, theN6-benzoyladenine molecule exists as the N(7)—H tautomer, and this tautomeric form is stabilized by intramolecular N—H...O hydrogen bonding between the benzoyl C=O group and the N(7)—H hydrogen on the Hoogsteen site of the purine ring, forming anS(7) motif. The dihedral angle between the adenine and phenyl planes is 0.94 (8)° in (I) and 9.77 (8)° in (II). In (I), the Watson–Crick face of BA (N6—H and N1; purine numbering) interacts with the carboxylate and phenol groups of 3HPA through N—H...O and O—H...N hydrogen bonds, generating a ring-motif heterosynthon [graph setR22(6)]. However, in (II), the Hoogsteen face of BA (benzoyl O atom and N7; purine numbering) interacts with TA (hydroxy and carbonyl O atoms) through N—H...O and O—H...O hydrogen bonds, generating a different heterosynthon [graph setR22(4)]. Both crystal structures are further stabilized by π–π stacking interactions.

Supramolecular Potential of Vanadium β-Diketonate and Picolinate Compounds and The First One-dimensional Oxidovanadium(IV) Complex with β-Diketonate Ligand

Three vanadium compounds with β-diketonato or picolinato ligands were prepared and structurally characterized. In compounds [VO(tfpb)2]∞ (1) (tfpb = 4,4,4-trifluoro-1-phenylbutane-1,3-dionate) and [VO(acac)2(2-pyridone)] (2) the coordination of vanadium atom is octahedral and in the compound Hpy[VO2(pic)Cl] (3) the central atom is pentacoordinated. X-Ray crystallographic studies reveal infinite chain formation due to V=O···V=O interactions in 1, while 2 and 3 are mononuclear compounds. Centrosymmetric hydrogen-bonded dimers are formed in 2 via N-H···O interactions due to the 2-pyridone ligand. In 3 the Hpy+ cation is hydrogen bonded to the complex anion and crystal structure is further stabilized by π···π and C-H···O interactions.