Mechanical flexibility in single crystals of covalently bound materials is a fascinating and poorly understood phenomenon. We present here the first example of a plastically flexible one‐dimensional (1D) coordination polymer. The compound [Zn(μ‐Cl)2(3,5‐dichloropyridine)2]n is flexible over two crystallographic faces. Remarkably, the single crystal remains intact when bent to 180°. A combination of microscopy, diffraction, and spectroscopic studies have been used to probe the structural response of the crystal lattice to mechanical bending. Deformation of the covalent polymer chains does not appear to be responsible for the observed macroscopic bending. Instead, our results suggest that mechanical bending occurs by displacement of the coordination polymer chains. Based on experimental and theoretical evidence, we propose a new model for mechanical flexibility in 1D coordination polymers. Moreover, our calculations propose a cause of the different mechanical properties of this compound and a structurally similar elastic material.
The ability to selectively tune the optical and the mechanical properties of organic molecular crystals offers a promising approach towards developing flexible optical devices. These functional properties are sensitive to...
Control over the bottom up synthesis of metal nanoparticles (NP) depends on many experimental factors, including the choice of stabilising and reducing agents. By selectively manipulating these species, it is...
Mechanochemistry
has become a valuable tool for the synthesis of
new molecules, especially in the field of organic chemistry. In the
present work, we investigate the kinetic profile of the chlorination
reaction of N-3-ethyl-5,5-dimethylhydantoin (EDMH)
activated and driven by ball milling. The reaction has been carried
out using 2 mm, 4 mm, 5 mm, 6 mm, and 8 mm ball sizes in a new small
custom-made Perspex milling jar. The crystal structure of the starting
material EDMH and the 1-chloro-3-ethyl-5,5′-dimethyl hydantoin
(CEDMH) chlorination product was solved by single-crystal X-ray diffraction.
The reaction was monitored, in situ and in real time,
by both powder X-ray diffraction (PXRD) and Raman spectroscopy. Our
kinetic data show that the reaction progress to equilibrium is similar
at all milling ball sizes. The induction period is very short (between
10 and 40 s) when using 4 mm, 5 mm, 6 mm, and 8 mm balls. For the
reaction performed with a 2 mm ball, a significantly longer induction
period of 9 min was observed. This could indicate that an initial
energy accumulation and higher mixing efficiency are necessary before
the reaction starts. Using different kinetic models, we found that
the amount of powder affected by critical loading conditions during
individual impacts is significantly dependent on the ball size used.
An almost linear correlation between the rate of the chemical transformations
and the ball volume is observed.
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