DL-Phenyl­alaninium tri­chloro­acetate

In the title compound, C₉H₁₂NO₂⁺·C₂Cl₃O₂⁻, the amino acid mol­ecule exists in the cationic form with a positively charged amino group and an uncharged carboxyl­ic acid group. The tri­chloro­acetic acid mol­ecule exists in the anionic state. The phenyl­alaninium cations and the tri­chloro­acetate anions form hydrogen-bonded double chains, linked together by N—H...O and O—H...O hydrogen bonds, extending along the c axis.

2,6-Bis(4-methoxy­phenyl)-1-nitro­so-3,5-di­phenyl­piperidin-4-one

The piperidone ring of the title compound, C₃₁H₂₈N₂O₄, adopts a twist boat conformation. The crystal packing is characterized by a layered arrangement of mol­ecules held together by C—H...O hydrogen bonds, in which each of the nitro­so and carbonyl O atoms participate. No significant aryl–aryl interactions are observed.

L-Phenyl­alanine L-phenyl­alaninium malonate

The asymmetric unit of the title compound, C₉H₁₁NO₂·C₉H₁₂NO₂⁺·C₃H₃O₄⁻, consists of two phenyl­alanine mol­ecules, one as a zwitterion (P) and the other as a cation (P⁺), in addition to a malonate anion (Mal⁻). The phenyl­alaninium and phenyl­alanine mol­ecules are linked by a very short syn–syn carbox­yl–carboxyl­ate (–COO⁻...HOOC–) hydrogen bond [O...O = 2.429 (4) Å]. The Mal⁻ anion is stabilized by a strong intra­molecular O—H...O hydrogen bond. The aggregation of P and P⁺ is mediated through Mal⁻, leading to an infinite double chain along the c axis.

β-DL-Methio­nine at 105 K

In the title compound, C₅H₁₁NO₂S, the conformation of the terminal meth­yl C atom with respect to the β-C atom is trans. The crystal structure is stabilized by a network of characteristic head-to-tail DL1 and DL2 sequences.

2,6-Bis(2-methyl­phen­yl)-1-nitroso-3,5-diphenyl­piperidin-4-one

In the title compound, C₃₁H₂₈N₂O₂ the piperidinone ring adopts a twist-boat conformation. A C—H...O hydrogen bond between mol­ecules related through a centre of inversion leads to the formation of dimers. These centrosymmetric dimers have no hydrogen-bond inter­actions between them and form columns running along the b axis through van der Waals inter­actions. In addition, a weak C—H...π inter­action involving the 2-methyl­phen­yl ring, with H...π = 2.64 Å and an angle of 170°, is observed.

2,6-Bis(2-methoxy­phen­yl)-1-nitroso-3,5-diphenyl­piperidin-4-one

The piperidone ring in the title compound, C₃₁H₂₈N₂O₄, adopts the usual twist–boat conformation. The configurations of the aryl rings at the 2- and 3-positions are equatorial and those at the 5- and 6-positions are axial. The crystal structure is characterized by C—H...O and C—H...N hydrogen bonds between centrosymmetrically related pairs of mol­ecules. In addition, there is an intra­molecular C—H...O hydrogen bond and a weak C—H...π inter­action. No significant ar­yl–aryl inter­actions were observed.

2,6-Bis(2-chloro­phen­yl)-1-nitroso-3,5-diphenyl­piperidin-4-one

In the title compound, C₂₉H₂₂Cl₂N₂O₂, the piperidinone ring adopts its usual twist–boat conformation. The crystal packing is stabilized by a three-dimensional network of C—H...O hydrogen bonds involving the nitroso and carbonyl O atoms. No significant C—H...π, π–π and Cl...Cl inter­actions are observed but there are weak Cl...Cl interactions.

L-Phenyl­alanine–benzoic acid (1/1)

In the title compound, C₉H₁₁NO₂·C₇H₆O₂, the amino acid mol­ecule exists as a zwitterion and the carboxylic acid mol­ecule is in an unionized state. There is a strong O—H...O inter­molecular hydrogen bond between the phenyl­alanine and benzoic acid mol­ecules, and these mol­ecular pairs form hydrogen-bonded double layers.