Poly[4,4′-imino­dipyridinium [tetra-μ3-oxido-tetra­oxido-di-μ4-phosphato-κ4 O:O′:O′′:O′′′-tetra­vanadium(V)]]

In the title salt, {(C10H11N3)[V4O8(PO4)2]}n, cubane-like [V4O8]4+ clusters are connected by phosphate anions into anionic [V4P2O16]n 2n− layers. These aggregate into the three-dimensional structure via N—H⋯O hydrogen-bonding mechanisms imparted by 4,4′-imino­dipyridinium dications situated between the layers

4-(4-Pyridylamino)pyridinium perchlorate

In the title salt, C10H10N3 +·ClO4 −, the 4-(4-pyridylamino)­pyridinium cations are linked into chains via N—H⋯N hydrogen bonding and into layers by C—H⋯π inter­actions [C⋯Cg = 3.3875 (19) Å]. Perchlorate ions are anchored to the layer motifs by N—H⋯O hydrogen bonding. The perchlorate anion was found to be disordered about a Cl—O axis, with two sites, each of equal occupancy, being resolved for the three remaining O atoms

1,4-Bis(4-pyridylmeth­yl)piperazin-1-ium perchlorate fumaric acid hemisolvate

In the title salt, C16H21N4 +·ClO4 −·0.5C4H4O4, fumaric acid mol­ecules, situated across crystallographic inversion centres, are O—H⋯N hydrogen bonded to two protonated 1,4-bis­(4-pyridylmeth­yl)piperazine cations, forming trimolecular units. These construct one-dimensional supra­molecular ribbons by N—H⋯N hydrogen bonding, and further aggregate via π–π inter­actions [shortest C⋯C contact = 3.640 (1) Å] and perchlorate-mediated C—H⋯O inter­actions

Poly[[diaqua­bis(μ3-maleato-κ4 O 1:O 1′,O 4:O4′)dicopper(II)] trihydrate]

In the title compound, {[Cu2(C4H2O4)2(H2O)2]·3H2O}n, CuII ions with square-pyramidal coordination are bridged by exo­tri­dentate maleate dianions into [Cu2(maleate)2(H2O)2]n layers coincident with the bc crystal plane. The inter­lamellar regions contain hydrogen-bonded cyclic water hexa­mers which facilitate layer stacking into a pseudo-three-dimensional crystal structure. The water hexamers themselves are formed by the operation of crystallographic inversion centers on sets of three crystallographically distinct water molecules of hydration

Bis(perchlorato-κO)tetra­kis[1-(2-pyridyl)-4-(4-pyridylmethyl-κN)piperazine]cadmium(II)

In the title compound, [Cd(ClO4)2(C15H18N4)4], the CdII ion is coordinated in a slightly distorted octa­hedral environment by two trans monodentate perchlorate ligands and four 1-(2-pyrid­yl)-4-(4-pyridylmeth­yl)piperazine (pmpp) ligands. In the crystal structure, mol­ecules are organized into layers parallel to the ab plane by C—H⋯O inter­actions. Similar inter­actions promote the stacking of these layers into the three-dimensional crystal structure

Bis(dimethyl­malonato-κ2 O,O′)bis­[4-(4-pyridylamino-κN 4)pyridinium]nickel(II) hexa­hydrate

In the title compound, [Ni(C5H6O4)2(C10H10N3)2]·6H2O, divalent nickel ions situated on the crystallographic twofold axis are octa­hedrally coordinated by four O atoms from two dimethyl­malonate ligands in a 1,3-chelating mode and two N atoms from two protonated monodentate 4,4′-dipyridylamine mol­ecules. The mol­ecules link into chains via N—H⋯O hydrogen bonding mediated by protonated pyridyl groups. The chains form layer patterns via π–π stacking [centroid–centroid distance = 3.777 (2) Å] . Water mol­ecule hexa­mers are generated from the unligated water mol­ecules (three per asymmetric unit) by inversion centers at Wyckoff position d. These clusters are situated between the pseudolayers, providing hydrogen-bonding pathways that build up the three-dimensional structure

catena-Poly[[[(dimethyl­malonato-κ2 O:O′)(perchlorato-κO)copper(II)]-μ-bis­(3-pyridylmeth­yl)piperazinediium-κ2 N 1′:N 4′] perchlorate dihydrate]

In the title compound, {[Cu(C5H6O4)(ClO4)(C16H22N4)]ClO4·2H2O}n, square-pyramidally coordinated Cu atoms with perchlorate and dimethyl­malonate ligands are connected into cationic sinusoidal coordination polymer chains by doubly protonated bis­(3-pyridylmeth­yl)piperazine (3-bpmp) ligands. The chains aggregate into pseudo-layers parallel to the (101) crystal planes by N—H⋯O hydrogen bonding. Unligated perchlorate anions and water mol­ecules of crystallization provide additional hydrogen bonding between pseudo-layers

Nanomechanical Contribution of Collagen and von Willebrand Factor A in Marine Underwater Adhesion and Its Implication for Collagen Manipulation

Recent works on mussel adhesion have identified a load bearing matrix protein (PTMP1) containing von Willebrand factor (vWF) with collagen binding capability that contributes to the mussel holdfast by manipulating mussel collagens. Using a surface forces apparatus, we investigate for the first time, the nanomechanical properties of vWF-collagen interaction using homologous proteins of mussel byssus, PTMP1 and preCollagens (preCols), as collagen. Mimicking conditions similar to mussel byssus secretion (pH < 5.0) and seawater condition (pH 8.0), PTMP1 and preCol interact weakly in the "positioning" phase based on vWF-collagen binding and strengthen in "locked" phase due to the combined effects of electrostatic attraction, metal binding, and mechanical shearing. The progressive enhancement of binding between PTMP1 with porcine collagen under the aforementioned conditions is also observed. The binding mechanisms of PTMP1-preCols provide insights into the molecular interaction of the mammalian collagen system and the development of an artificial extracellular matrix based on collagens.1142sciescopu