Conformation and structure of bis­(glycyl-L-aspartic acid) oxalate 0.4-hydrate

The title bis­(glycyl-L-aspartic acid) oxalate complex {systematic name: bis­[2-(2-ammonio­acetamido)butane­dioic acid] oxalate 0.4-hydrate}, 2C₆H₁₁N₂O₅⁺·C₂O₄²⁻·4H₂O, crystallizes in a triclinic space group with the planar peptide unit in a trans conformation. The asymmetric unit consists of two glycyl-L-aspartic acid mol­ecules with positively charged amino groups and neutral carboxyl groups, and an oxalate dianion. The twist around the C—Cα bond indicates that both the peptide mol­ecules adopt extended conformations, while the twist around the N—Cα bond shows that one has a folded and the other a semi-extended state. The present complex can be described as an inclusion compound with the dipeptide mol­ecule as the host and the oxalate anion as the guest. The usual head-to-tail sequence of aggregation is not observed in this complex, as is also the case with the glycyl-L-aspartic acid dihydrate mol­ecule. The study of aggregation and inter­action patterns in binary systems is the first step towards understanding more complex phenomena. This further leads to results that are of general interest in bimolecular aggregation.

A series of substituted (2E)-3-(2-fluoro-4-phenoxy­phen­yl)-1-phenyl­prop-2-en-1-ones

In the mol­ecular structures of a series of substituted chalcones, namely (2E)-3-(2-fluoro-4-phenoxy­phen­yl)-1-phenyl­prop-2-en-1-one, C₂₁H₁₅FO₂, (I), (2E)-3-(2-fluoro-4-phenoxy­phen­yl)-1-(4-fluoro­phen­yl)prop-2-en-1-one, C₂₁H₁₄F₂O₂, (II), (2E)-1-(4-chloro­phen­yl)-3-(2-fluoro-4-phenoxy­phen­yl)prop-2-en-1-one, C₂₁H₁₄ClFO₂, (III), (2E)-3-(2-fluoro-4-phenoxy­phen­yl)-1-(4-methyl­phen­yl)prop-2-en-1-one, C₂₂H₁₇FO₂, (IV), and (2E)-3-(2-fluoro-4-phenoxy­phen­yl)-1-(4-methoxy­phen­yl)prop-2-en-1-one, C₂₂H₁₇FO₃, (V), the configuration of the keto group with respect to the olefinic double bond is s-cis. The mol­ecules pack utilizing weak C—H...O and C—H...π inter­molecular contacts. Identical packing motifs involving C—H...O inter­actions, forming both chains and dimers, along with C—H...π dimers and π–π aromatic inter­actions are observed in the fluoro, chloro and methyl derivatives.

Four substituted pyrazolines

In the title compounds 5-(3-fluoro-4-phenoxy­phenyl)-1,3-biphenyl-4,5-dihydro-1H-pyrazole, C₂₇H₂₁FN₂O, (I), 3-(4-chloro­phenyl)-5-(3-fluoro-4-phenoxy­phenyl)-1-phenyl-4,5-dihydro-1H-pyrazole, C₂₇H₂₀ClFN₂O, (II), 5-(3-fluoro-4-phen­oxy­phenyl)-3-(4-methyl­phenyl)-1-phenyl-4,5-dihydro-1H-pyrazole, C₂₈H₂₃FN₂O, (III), and 5-(3-fluoro-4-phenoxy­phenyl)-3-(4-methoxy­phenyl)-1-phenyl-4,5-dihydro-1H-pyrazole, C₂₈H₂₃FN₂O₂, (IV), the five-membered pyrazole ring exists in an envelope conformation. The crystal structure of (I) has three independent C—H...π inter­molecular inter­actions. In (II), an inter­molecular C—Cl...π contact is present, forming mol­ecular chains. Replacement of this chloro group in (II) by a methyl group yields an isomorphic crystal structure, (III).