An NMR crystallography DFT-D approach to analyse the role of intermolecular hydrogen bonding and π–π interactions in driving cocrystallisation of indomethacin and nicotinamide

Electrostatic interactions, and specifically π-interactions play a significant role in the liquid-liquid phase separation of proteins and formation of membraneless organelles/or biological condensates. Sequence patterning of peptides allows creating protein-like structures and controlling the chemistry and interactions of the mimetic molecules. A library of oppositely charged polypeptides was designed and synthesized to investigate the role of π-interactions on phase separation and secondary structures of polyelectrolyte complexes. Phenylalanine was chosen as the π-containing residue and was used together with lysine or glutamic acid in the design of positively or negatively charged sequences. The effect of charge density and also the substitution of fluorine on the phenylalanine ring, known to disrupt π-interactions, were investigated. Characterization analysis using MALDI-TOF mass spectroscopy, H NMR, and circular dichroism (CD) confirmed the molecular structure and chiral pattern of peptide sequences. Despite an alternating sequence of chirality previously shown to promote liquid-liquid phase separation, complexes appeared as solid precipitates, suggesting strong interactions between the sequence pairs. The secondary structures of sequence pairs showed the formation of hydrogen-bonded structures with a β-sheet signal in FTIR spectroscopy. The presence of fluorine decreased hydrogen bonding due to its inhibitory effect on π-interactions. π-interactions resulted in enhanced stability of complexes against salt, and higher critical salt concentrations for complexes with more π-containing amino acids. Furthermore, UV-vis spectroscopy showed that sequences containing π-interactions and increased charge density encapsulated a small charged molecule with π-bonds with high efficiency. These findings highlight the interplay between ionic, hydrophobic, hydrogen bonding, and π-interactions in polyelectrolyte complex formation and enhance our understanding of phase separation phenomena in protein-like structures.

Download Full-text

(Acetylacetonato-κ2O,O′)[1-(4-bromophenyl-κC2)-3-methylimidazol-2-ylidene-κC2]platinum(II)

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s0108270112027783 ◽

2012 ◽

Vol 68 (8) ◽

pp. m203-m205 ◽

Cited By ~ 14

Author(s):

Mario Tenne ◽

Yvonne Unger ◽

Thomas Strassner

Keyword(s):

Hydrogen Bonding ◽

Solid State ◽

Intermolecular Hydrogen Bonding ◽

Coordination Environment ◽

Π Interactions ◽

New Class ◽

Square Planar ◽

Parallel Fashion

The title platinum(II) complex, [Pt(C10H8BrN2)(C5H7O2)], has a bidentate cyclometallated phenylimidazolylidene ligand and an acetylacetonate spectator ligand, which form a distorted square-planar coordination environment around the PtIIcentre. In the solid state, the molecules are oriented in a parallel fashion by intermolecular hydrogen bonding and π–π and C—H...π interactions, while close Pt...Pt contacts are not observed. The structure is only the second example for this new class of compounds.

Download Full-text

Role of base arrangements and intermolecular hydrogen bonding in charge-transfer states of thymine-adenine dinucleotide in aqueous solution

Journal of Photochemistry and Photobiology A Chemistry ◽

10.1016/j.jphotochem.2017.01.001 ◽

2017 ◽

Vol 337 ◽

pp. 1-5 ◽

Cited By ~ 5

Author(s):

Jian Luo ◽

Yan Liu ◽

Songqiu Yang

Keyword(s):

Aqueous Solution ◽

Hydrogen Bonding ◽

Charge Transfer ◽

Intermolecular Hydrogen Bonding ◽

Thymine Adenine

Download Full-text

On the role of intermolecular hydrogen bonding in miscible polymer blends

Macromolecules ◽

10.1021/ma00139a006 ◽

1984 ◽

Vol 17 (9) ◽

pp. 1671-1678 ◽

Cited By ~ 123

Author(s):

E. J. Moskala ◽

S. E. Howe ◽

Paul C. Painter ◽

Michael M. Coleman

Keyword(s):

Hydrogen Bonding ◽

Polymer Blends ◽

Intermolecular Hydrogen Bonding ◽

Miscible Polymer Blends

Download Full-text

Crystal structures of chlorido[dihydroxybis(1-iminoethoxy)]arsanido-κ3 N,As,N′]platinum(II) and of a polymorph of chlorido[dihydroxybis(1-iminopropoxy)arsanido-κ3 N,As,N′]platinum(II)

Acta Crystallographica Section E Crystallographic Communications ◽

10.1107/s2056989019016463 ◽

2020 ◽

Vol 76 (2) ◽

pp. 180-185

Author(s):

Nina R. Marogoa ◽

D.V. Kama ◽

Hendrik G. Visser ◽

M. Schutte-Smith

Keyword(s):

Crystal Structure ◽

Hydrogen Bonding ◽

Crystal Structures ◽

Three Dimensional ◽

Donor Ligands ◽

Intermolecular Hydrogen Bonding ◽

Π Interactions ◽

Hydrogen Bonding Interactions ◽

Oxygen Donor ◽

Dimensional Network

Each central platinum(II) atom in the crystal structures of chlorido[dihydroxybis(1-iminoethoxy)arsanido-κ3 N,As,N′]platinum(II), [Pt(C4H10AsN2O4)Cl] (1), and of chlorido[dihydroxybis(1-iminopropoxy)arsanido-κ3 N,As,N′]platinum(II), [Pt(C6H14AsN2O4)Cl] (2), is coordinated by two nitrogen donor atoms, a chlorido ligand and to arsenic, which, in turn, is coordinated by two oxygen donor ligands, two hydroxyl ligands and the platinum(II) atom. The square-planar and trigonal–bipyramidal coordination environments around platinum and arsenic, respectively, are significantly distorted with the largest outliers being 173.90 (13) and 106.98 (14)° for platinum and arsenic in (1), and 173.20 (14)° and 94.20 (9)° for (2), respectively. One intramolecular and four classical intermolecular hydrogen-bonding interactions are observed in the crystal structure of (1), which give rise to an infinite three-dimensional network. A similar situation (one intramolecular and four classical intermolecular hydrogen-bonding interactions) is observed in the crystal structure of (2). Various π-interactions are present in (1) between the platinum(II) atom and the centroid of one of the five-membered rings formed by Pt, As, C, N, O with a distance of 3.7225 (7) Å, and between the centroids of five-membered (Pt, As, C, N, O) rings of neighbouring molecules with distances of 3.7456 (4) and 3.7960 (6) Å. Likewise, weak π-interactions are observed in (2) between the platinum(II) atom and the centroid of one of the five-membered rings formed by Pt, As, C, N, O with a distance of 3.8213 (2) Å, as well as between the Cl atom and the centroid of a symmetry-related five-membered ring with a distance of 3.8252 (12) Å. Differences between (2) and the reported polymorph [Miodragović et al. (2013). Angew. Chem. Int. Ed. 52, 10749–10752] are discussed.

Download Full-text