Kaliyaperumal Thanigaimani

Hydrogen‐bonded supramolecular motifs in 2‐amino‐4,6‐dimethoxypyrimidinium 4‐hydroxybenzoate monohydrate, 2‐amino‐4,6‐dimethoxypyrimidinium 6‐carboxypyridine‐2‐carboxylate monohydrate and 2‐amino‐4,6‐dimethoxypyrimidinium hydrogen (2R,3R)‐tartrate 2‐amino‐4,6‐dimethoxypyrimidine

In the crystal structures of the title compounds, C(6)H(10)N(3)O(2)+.C(7)H(5)O(3)-.H2O, (I), C(6)H(10)N(3)O(2)+.C(7)H(4)NO(4)-.H2O, (II), and C(6)H(10)N(3)O(2)+.C(4)H(5)O(6)-.C(6)H(9)N(3)O(2), (III), the 2-amino-4,6-dimethoxypyrimidinium cation [abbreviated as (MeO)2-Hampy+] interacts with the carboxylate group of the corresponding anion through a pair of nearly parallel N-H...O hydrogen bonds to form R(2)(2)(8) ring motifs. In (I), the (MeO)2-Hampy+ cation is centrosymmetrically paired through a pair of N-H...N hydrogen bonds involving the 2-amino group and a ring N atom forming an R(2)(2)(8) motif. In (II), inversion-related R(2)(2)(8) motifs (amino-pyrimidine-carboxylate motifs) are further bridged by N-H...O hydrogen bonds on either side forming a DDAA array of quadruple hydrogen bonds. This array is extended further on either side by O(water)-H...O(methoxy) hydrogen bonds, resulting in an array of six hydrogen bonds (ADDAAD). The water molecule plays a pivotal role, and five hydrogen-bonded fused rings are formed around the water molecule. In (III), the carboxy group of the tartrate anion interacts with the ring N atom and 2-amino group of the neutral (MeO)2-ampy molecule through N-H...O and O-H...N hydrogen bonds. There is also an intramolecular O-H...O hydrogen bond in the tartrate anion. In all three crystal structures, C-H...O hydrogen bonds are observed.

Charge‐assisted hydrogen‐bonded supramolecular networks in acetoguanaminium hydrogen phthalate, acetoguanaminium hydrogen maleate and acetoguanaminium 3‐hydroxypicolinate monohydrate

In 2,4-diamino-6-methyl-1,3,5-triazin-1-ium (acetoguanaminium) hydrogen phthalate, C(4)H(8)N(5)(+) x C(8)H(5)O(4)(-), (I), acetoguanaminium hydrogen maleate, C(4)H(8)N(5)(+) x C(4)H(3)O(4)(-), (II), and acetoguanaminium 3-hydroxypicolinate monohydrate, C(4)H(8)N(5)(+) x C(6)H(4)NO(3)(-) x H(2)O, (III), the acetoguanaminium cations interact with the carboxylate groups of the corresponding anions via a pair of nearly parallel N-H...O hydrogen bonds, forming R(2)(2)(8) ring motifs. In (II) and (III), N-H...N base-pairing is observed, while there is none in (I). In (II), a series of fused R(3)(2)(8), R(2)(2)(8) and R(3)(2)(8) hydrogen-bonded rings plus fused R(2)(2)(8), R(6)(2)(12) and R(2)(2)(8) ring motifs occur alternately, aggregating into a supramolecular ladder-like arrangement. In (III), R(2)(2)(8) motifs occur on either side of a further ring formed by pairs of N-H...O hydrogen bonds, forming an array of three fused hydrogen-bonded rings. In (I) and (II), the anions form a typical intramolecular O-H...O hydrogen bond with graph set S(7), whereas in (III) an intramolecular hydrogen bond with graph set S(6) is formed.

Hydrogen‐bonding patterns in 2‐amino‐4,6‐dimethoxypyrimidine–phthalic acid (1/1)

In the title cocrystal, C6H9N3O2·C8H6O4, both carboxylic acid groups of phthalic acid form an R22(8) ring motif (through N—H...O and O—H...N hydrogen bonds) on either side of the 2-amino-4,6-dimethoxypyrimidine molecule, generating a helical chain along the b axis. This chain is interpenetrated by a centrosymmetrically related chain to which it is linked by π–π stacking [perpendicular separation 3.332 A, centroid–centroid distance 3.6424 (7) A].

Hydrogen-bonded supramolecular motifs in pyrimethaminium 4-methylbenzoate, pyrimethaminium 3-hydroxypicolinate and pyrimethaminium 2,4-dichlorobenzoate.

In 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium (pyrimethaminium, PMNH) 4-methylbenzoate, C(12)H(14)ClN(4)(+) x C(8)H(7)O(2)(-), (I), pyrimethaminium 3-hydroxypicolinate, C(12)H(14)ClN(4)(+) x C(6)H(4)NO(3)(-), (II), and pyrimethaminium 2,4-dichlorobenzoate, C(12)H(14)ClN(4)(+) x C(7)H(3)Cl(2)O(2)(-), (III), the PMNH cations interact with the carboxylate groups of the corresponding anion via nearly parallel N-H...O hydrogen bonds, forming R(2)(2)(8) ring motifs. A description of the observed arrays of quadruple hydrogen bonds in (I) and (II) in terms of hydrogen donors and acceptors (the DA model), their graph-set motifs and the resulting supramolecular ladder is given. In (III), supramolecular chains along the b axis and helical chains along the a axis are formed via N-H...O hydrogen bonds involving the 2-amino and 4-amino groups of the PMNH cation, respectively. Weak Cl...Cl interactions are also found in (III).

2-Meth-oxy-anilinium 3-hy-droxy-2,4,6-trinitro-phenolate.

The cation and anion of the title molecular salt, C7H10NO+·C6H2N3O8 −, are linked via an N—H⋯O hydrogen bond. An intramolecular O—H⋯O hydrogen bond is also found in the anion. In the crystal, the anions self-assemble via O—H⋯O hydrogen bonds, forming a C(9) supramolecular chain the b axis. Further intermolecular N—H⋯O interactions also occur.

Hydrogen-bonding patterns in the cocrystal 2-amino-4,6-dimethoxy­pyrimidine–anthranilic acid (1/1)

In the title cocrystal, C6H9N3O2·C7H7NO2, the asymmetric unit contains two crystallographically independent 2-amino-4,6-dimethoxy pyrimidine-anthranilic acid adducts. The 2-amino-4,6-dimethoxy pyrimidine molecules interact with the carboxylic group of the respective anthranilic acid molecules through N—H⋯O and O—H⋯N hydrogen bonds, forming a cyclic hydrogen-bonded motif R 2 2(8). The pyrimidine molecules also form base pairs via a pair of N—H⋯N hydrogen bonds, forming another R 2 2(8) motif. The typical intramolecular N—H⋯O hydrogen bond is observed in the anthranilic acid molecules. Furthermore, the crystal structure is stabilized by C—H⋯O hydrogen bonds.

Stereoselective Synthesis of Polyfunctionalized Nitrothianes: Enhancement of Stereoselectivity by Microwaves

Abstract The Michael addition of nitromethane to (Z,Z)-2,2′-thiobis(1,3-diarylprop-2-en-1-ones) in the presence of NaOEt in dimethylformamide (DMF)/alcohol under thermal conditions affords a diastereomeric mixture of 2a,6e-diaroyl-3a,5e-diaryl-4e-nitrothianes and 2e,6e-diaroyl-3e,5e-diaryl-4e-nitrothianes with a dr of ∼3:1/4:1 respectively. This reaction under microwave irradiation in DMF/alcohol afforded solely 2a,6e-diaroyl-3a,5e-diaryl-4e-nitrothianes, disclosing enhancement of stereoselectivity by microwaves. Supplemental materials are available for this article. Go to the publishers online edition of Synthetic Communications® to view the free supplemental file. GRAPHICAL ABSTRACT

8-Hy­droxy-5,7-dimethyl­quinolin-1-ium chloride dihydrate

In the title hydrated salt, C11H12NO+·Cl−·2H2O, the quinoline ring system is essentially planar, with a maximum deviation of 0.005 (1) Å for all non-H atoms. In the crystal, the three components are linked by O—H⋯O, N—H⋯O, O—H⋯Cl and weak C—H⋯O hydrogen bonds, forming a layer structure parallel to the ac plane. The crystal structure is further stabilized by π–π stacking interactions, with centroid–centroid distances of 3.5213 (6) and 3.7176 (6) Å.

Supramolecular patterns and Hirshfeld surface analysis in the crystal structure of bis(2-amino-4-methoxy-6-methylpyrimidinium) isophthalate

The structure of the substituted 2-aminopyrimidine salt of isophthalic acid comprises an almost planar unit in which the two pyrimidinium cations are cyclically hydrogen-bonded to the succinate dianion and further extended through hydrogen bonds into a one-dimensional supramolecular structure.