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1. Effects of molecular flexibility and head group repulsion on aramid amphiphile self-assembly

   https://doi.org/10.1039/d1me00120e  

   Kaser, Samuel J.; Lew, Andrew J.; Kim, Dae-Yoon; Christoff-Tempesta, Ty; Cho, Yukio; Ortony, Julia H. (November 2021, Molecular Systems Design & Engineering)

   The self-assembly of amphiphilic molecules in water has led to a wide variety of nanostructures with diverse applications. Many nanostructures are stabilized by strong interactions between monomer units, such as hydrogen bonding and π–π stacking. However, the morphological implications of these strong, anisotropic interactions can be difficult to predict. In this study, we investigate the relationships between molecular flexibility, head group repulsion, and supramolecular geometry in an aramid amphiphile nanostructure that is known to exhibit extensive hydrogen bonding and π–π stacking – features that give rise to their unusual stability. We find by electron microscopy that increasing backbone flexibility disrupts molecular packing into high aspect-ratio nanoribbons, and at the highest degree of flexibility long-range ordering is lost. Even when backbone rigidity favors tight packing, increasing head group charge through pH-modulation leads to intermolecular electrostatic repulsion that also disrupts close packing. Spectroscopic measurements suggest that these changes are accompanied by disruption of π–π stacking but not hydrogen bonding. Backbone rigidity and head group repulsion are thus important design considerations for controlling internal stability and nanostructure curvature in supramolecular assemblies stabilized by π–π stacking interactions. 

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2. Crystal structure of cis -[1,2-bis(diphenylphosphanyl)ethene-κ ² P , P ′]dichloridoplatinum(II) chloroform disolvate: a new polymorph

   https://doi.org/10.1107/S2056989018008836  

   Mugemana, Jimmy; Bender, John; Staples, Richard J.; Biros, Shannon M. (July 2018, Acta Crystallographica Section E Crystallographic Communications)

   The title compound, [PtCl 2 (C 26 H 22 P 2 )]·2CHCl 3 (I), is the third monoclinic polymorph of this platinum(II) complex involving the bidentate ligand cis -1,2-bis(diphenylphosphanyl)ethylene ( cis -dppe) [for the others, see: Oberhauser et al. (1998 a ). Inorg. Chim. Acta , 274 , 143–154, and Oberhauser et al. (1995). Inorg. Chim. Acta , 238 , 35–43]. The structure of compound (I) was solved in the space group P 2 1 / c , with one complex molecule in the asymmetric unit along with two solvate chloroform molecules. The Pt II atom is ligated by two P and two Cl atoms in the equatorial plane and has a perfect square-planar coordination sphere. In the crystal, the complex molecule is linked to the chloroform solvate molecules by C—H...Cl hydrogen bonds and face-on C—Cl...π interactions. There are also weak offset π–π interactions present [intercentroid distances are 3.770 (6) and 4.096 (6) Å], linking the molecules to form supramolecular sheets that lie in the bc plane. 

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3. Dichlorido{(E)-N,N-dimethyl-2-[phenyl(pyridin-2-yl)methylidene]hydrazine-1-carbothioamide}cadmium(II)

   https://doi.org/10.1107/S241431462500464X  

   Parry, Christian S; Kwabi-Addo, Bernard; Ramadhar, Timothy R; Butcher, Raymond J (May 2025, IUCrData)

   The structure of the title compound, [CdCl₂(C₁₅H₁₆N₄S)], at 100 K has monoclinic (P2₁/c) symmetry. The compound has a layer structure and is a 1:1 complex of the organic ligand and cadmium chloride. The ligand, 3,3-dimethyl-1-[(E)-[phenyl(pyridine-2-yl)methylidene]amino]thiourea (L, Bp44mT), is of interest with respect to anticancer activity, antiviral properties and potential use in conditions of iron overload, from hemochromatosis or from multiple transfusions in hematological disorders such as sickle cell disease or beta thalassemia. This study is aimed at uncovering the basis of selectivity of the ligand as a chelator and for lead optimization. We also examine the ligand's potential use in treating heavy metal poisoning from cadmium, arsenic, lead or mercury, and for environmental remediation. The crystal structure exhibits no intermolecular or intramolecular hydrogen bonding with the supramolecular features being driven by hydrophobic, π–π and long-range dispersion forces. 

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4. X-ray crystal structure of trans -bis(pyridin-3-yl)ethylene: comparing the supramolecular structural features among the symmetrical bis( n -pyridyl)ethylenes ( n = 2, 3, or 4) constitutional isomers

   https://doi.org/10.1107/S2056989020015303  

   Quentin, Jay; Reinheimer, Eric W.; MacGillivray, Leonard R. (December 2020, Acta Crystallographica Section E Crystallographic Communications)

   null (Ed.)

   The molecular structure of trans -bis(pyridin-3-yl)ethylene ( 3,3′-bpe ), C 12 H 10 N 2 , as determined by single-crystal X-ray diffraction is reported. The molecule self-assembles into two dimensional arrays by a combination of C—H...N hydrogen bonds and edge-to-face C—H... π interactions that stack in a herringbone arrangement perpendicular to the crystallographic c -axis. The supramolecular forces that direct the packing of 3,3′-bpe as well as its packing assembly within the crystal are also compared to those observed within the structures of the other symmetrical isomers trans -1,2-bis( n -pyridyl)ethylene ( n , n ′-bpe , where n = n ′ = 2 or 4). 

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5. Synthesis, structural analysis, and docking studies with SARS-CoV-2 of a trinuclear zinc complex with N -phenylanthranilic acid ligands

   https://doi.org/10.1107/S205322962200239X  

   Mbani O., Armel L.; Bonnand, Evan F.; Paboudam, Awawou G.; Brannon, Jacob P.; Gardner-Ricossa, Kevyn D.; Stieber, S. Chantal; Agwara, Moise O. (April 2022, Acta Crystallographica Section C Structural Chemistry)

   The structure of a trinuclear zinc complex, hexakis(μ 2 -2-anilinobenzoato)diaquatrizinc(II), [Zn 2 (C 13 H 10 NO 2 ) 6 (H 2 O) 2 ] or (NPA) 6 Zn 3 (H 2 O) 2 (NPA is 2-anilinobenzoate or N -phenylanthranilate), is reported. The complex crystallizes in the triclinic space group P -1 and the central Zn II atom is located on an inversion center. The NPA ligand is found to coordinate via the carboxylate O atoms with unique C—O bond lengths that support an unequal distribution of resonance over the carboxylate fragment. The axial H 2 O ligands form hydrogen bonds with neighboring molecules that stabilize the supramolecular system in rigid straight chains, with an angle of 180° along the c axis. π stacking is the primary stabilization along the a and b axes, resulting in a highly ordered supramolecular structure. Docking studies show that this unique supramolecular structure of a trinuclear zinc complex has potential for binding to the main protease (M pro ) in SARS-CoV-2 in a different location from Remdesivir, but with a similar binding strength. 

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