Solvent-Free Synthesis of Luminescent Copper(I) Coordination Polymers with Thiourea Derivatives

This
communication reports the solvent-free synthesis of a series
of copper­(I) cyanide (CuCN) -based coordination polymers showing interesting
luminescence properties and specific three-dimensional structures.
The new compounds have been achieved by directly grinding CuCN together
with thiourea (tu), N-methylthiourea (mtu), N-phenylthiourea (ptu), N,N′-diphenylthiourea (dptu), and 2,4-difluorophenylthiourea
(fptu). The resulting compounds are [(CuCN)2(tu)]n, [(CuCN)5(mtu)3]n, [(CuCN)3(mtu)2]n, [CuCN­(ptu)]n, [CuCN­(dptu)]n, and [(CuCN)3(fptu)2]n. “Seeding” crystallization
was successful for [(CuCN)2(tu)]n, [CuCN­(ptu)]n, [CuCN­(dptu)]n, and [(CuCN)3(fptu)2]n, and their structures have been resolved
using X-ray single crystal diffraction. Owing to the microcrystalline
powdered nature of compounds [(CuCN)5(mtu)3]n and [(CuCN)3(mtu)2]n, their characterization was
mainly based on solid-state NMR, via 13C cross polarization
magic angle spinning for ligand coordination and 1H magic
angle spinning for the weak interactions involving hydrogen atoms.
Other solid-state techniques (infrared spectroscopy, X-ray powder
diffraction, differential scanning calorimetry, and thermogravimetric
analysis) completed the characterization. Finally, the luminescence
properties were explored by recording emission and excitation spectra
and by evaluating the luminescence quantum yields and lifetimes. Such
in-depth study gives promising results for the potential application
as luminescent sensors of such compounds.