Poly[1,3-Dimethyltetrahydropyrimidin-2(1H)-iminium [tri-µ2-cyanido-κ6C:N-dicuprate(I)]]

The title compound contains a guanidinium cation that was unexpectedly found during X-ray single crystal analysis of a copper(I) cyanide network expected to contain protonated N,N’-dimethyl-1,3-diaminopropane. The cation was presumably formed by reaction of the amine with cyanide ions in the aqueous sodium cyanide/copper cyanide mixtures used in the synthesis. The structure of the network solid features the guanidinium cation as a guest in an anionic two-dimensional polymeric framework with stoichiometry Cu2(CN)3−. Confirmation of the structure was provided by analytical, thermal gravimetric and infrared data.

High pressure and elastic properties of a guanidinium-formate hybrid perovskite

The structural anisotropy of [C(NH2)3][Cd(HCOO)3] is regulated by guanidinium cation, and its orientation makes the young's modulus representation show a huge rigid response.

Factors Influencing the Activity of Nanozymes in the Cleavage of an RNA Model Substrate

A series of 2-nm gold nanoparticles passivated with different thiols all featuring at least one triazacyclonanone-Zn(II) complex and different flanking units (a second Zn(II) complex, a triethyleneoxymethyl derivative or a guanidinium of arginine of a peptide) were prepared and studied for their efficiency in the cleavage of the RNA-model substrate 2-hydroxypropyl-p-nitrophenyl phosphate. The source of catalysis for each of them was elucidated from the kinetic analysis (Michaelis–Menten profiles, pH dependence and kinetic isotope effect). The data indicated that two different mechanisms were operative: One involving two Zn(II) complexes and the other one involving a single Zn(II) complex and a flanking guanidinium cation. The mechanism based on a dinuclear catalytic site appeared more efficient than the one based on the cooperativity between a metal complex and a guanidinium.

Quantifying the Strength of a Salt Bridge by Neutron Scattering and Molecular Dynamics

The molecular structure and strength of a model salt bridge between a guanidinium cation as the charged side chain group of arginine and the carboxylic group of acetate in an aqueous solutions is characterized by a combination of neutron diffraction with isotopic substitution and molecular dynamics simulations. Being able to recover the second order difference signal, the present neutron scattering experiments provide direct information about ion pairing in the investigated solution. At the same time, these measurements serve as benchmarks for assessing the quality of the force field employed in the simulation. We show that a standard non-polarizable force field, which tends to overestimate the strength of salt bridges, does not reproduce the structural features from neutron scattering pertinent to ion pairing. In contrast, a quantitative agreement with experiment is obtained when electronic polarization effects are accounted for in a mean-field way via charge scaling. Such simulations are then used to quantify the weak character of a fully hydrated salt bridge. Finally, on top of the canonical hydrogen-bonding binding mode between guanidinium and acetate, these simulations also point to another interaction motif involving an out-of-plane hydrophobic contact of the methyl group of acetate with the guanidinium cation.