The salt-type 1:2 adduct of meso-5,5,7,12,12,14-hexa-C-methyl-1,4,8,11-tetraazacyclotetradecane (tet-a) and 5-nitroisophthalic acid forms a hydrogen-bonded sheet structure containing two configurational isomers of [(tet-a)H2]2+.

The title compound, meso-5,7,7,12,14,14-hexamethyl-4,11-diaza-1,8-diazoniacyclotetradecane bis(3-carboxy-5-nitrobenzoate), C(16)H(38)N(4)(2+).2C(8)H(4)NO(6)(-), is a salt in which the cation is present as two configurational isomers, disordered across a common centre of inversion in P1, with occupancies of 0.847 (3) and 0.

Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines.

(S)-Malic acid forms a salt with N,N'-dimethylpiperazine, [MeN(CH(2)CH(2))(2)NMe]H(2)(2+) x 2C(4)H(5)O(5)(-) (1) (triclinic, P1, Z' = 1), in which the cations link pairs of hydrogen-bonded anion chains to form a molecular ladder. With 4,4'-bipyridyl, (S)-malic acid forms a 1:1 adduct which crystallizes from methanol to yield two polymorphs, (2) (triclinic, P1, Z' = 1) and (3) (monoclinic, C2, Z' = 1), while racemic malic acid with 4,4'-bipyridyl also forms a 1:1 adduct, (4) (monoclinic, P2(1)/c, Z' = 1). In each of (2), (3) and (4) the components are linked by O[bond]H.

Amino-substituted O(6)-benzyl-5-nitrosopyrimidines: interplay of molecular, molecular-electronic and supramolecular structures.

The structures of eight 2,4,6-trisubstituted-5-nitrosopyrimidines (one of which crystallizes in two polymorphs) have been determined, including seven O(6)-benzyl derivatives which are potential, or proven, in vitro inhibitors of the human DNA-repair protein O(6)-alkylguanine-DNA-transferase. In the derivatives having an amino substituent at the 4-position, an intramolecular N-H.O hydrogen bond with the nitroso O as an acceptor leads to an overall molecular shape similar to that of substituted purines.

Polymorphs and pseudopolymorphs of N,N'-dithiobisphthalimide.

N,N'-Dithiobisphthalimide, C(16)H(8)N(2)O(4)S(2) (I), forms a wide range of polymorphs and solvates (pseudopolymorphs). When (I) is crystallized from methanol it yields a solvent-free polymorph (4), in Pna2(1) with Z' = 1, in which the molecules are linked into chains by a single C-H.O hydrogen bond: crystallization from either acetonitrile or dimethylformamide produces a monoclinic polymorph (5), in P2(1)/c with Z' = 2, also solvent-free, in which the molecules are linked into molecular ladders.

Chiral versus racemic building blocks in supramolecular chemistry: tartrate salts of organic diamines.

In the 1:1 adducts C(12)H(10)N(2).C(4)H(6)O(6) formed between 1,2-bis(4'-pyridyl)ethene and racemic tartaric acid [(I), triclinic P1;, Z' = 1] and (2R,3R)-tartaric acid [(II), triclinic P1, Z' = 2], the ionic components are linked by hard hydrogen bonds into single sheets, which are further linked by C-H.O hydrogen bonds.

A structural hierarchy in the hydrogen-bonded adduct N,N'-dimethylpiperazine-tartaric acid-water (1/2/2): an N-component N-dimensional structure (N =3) with substructures having N = 1 and 2.

In the hydrated adduct N,N'-dimethylpiperazine-1,4-diium bis(3-carboxy-2,3-dihydroxypropanoate) dihydrate, [MeNH(CH2CH2)2NHMe]2+*2(C4H5O6)-*2H2O or C6H16N2(2+)*2C4H5O6-*2H2O, formed between racemic tartaric acid and N,N'-dimethylpiperazine (triclinic P-1, Z' = 0.5), the cations lie across centres of inversion. The anions alone form chains, and anions and water molecules together form sheets; the sheets are linked by the cations to form a pillared-layer framework.