Subtle C–H···Hal (Hal = Cl, Br) Bonding as Predominant Synthon in the Assembly of Supramolecular Architectures Based on Luminescent Tin(IV) Complexes. Crystallography, Hirshfeld Surfaces, DFT Calculations, and Fluorescence

This report illustrates a successful
C–H···Hal
synthon-directed strategy to promote supramolecular aggregation of
molecular luminescent complexes 1–6 into two- or three-dimensional supramolecular architectures. The
tin complexes were prepared from the reaction of RnSnHal4–n compounds (R = n-Bu, Ph; Hal = Cl, Br; n = 0, 1) with
(C5H4N)­HCN­(C6H4)­EH Schiff bases by either step-by-step synthesis [E = O (PyNO)]
or multicomponent reaction [E = S (PyNS)]. Compounds 1–6 were characterized by IR, Raman, and 1H, 13C, and 119Sn NMR spectroscopic
studies as well as by X-ray diffraction studies. In addition, the
fluorescent properties of all compounds were also investigated in
the solid state and in THF solutions; the emission wavelengths ranged
from orange to red (λmax = 591–626 nm). Detailed
structural characterization of the supramolecular organization of
ordered solids revealed overall 2D and 3D interlinked networks driven
by extensive C–H···Hal–Sn (Hal = Cl,
Br) weak hydrogen bonds as primordial synthon and further stabilized
by π···π stacking interactions as well
as C–H···π, C–H···O,
or C–H···N contacts. Hirshfeld surface analysis
and DFT calculations were used to asses additional insights into crystal
structural features.