The role of weak intermolecular interactions in photophysical behavior of isocoumarins on the example of their interaction with cyclic trinuclear silver(I) pyrazolate

The complexation of 6-substituted isocoumarins with cyclic trinuclear silver pyrazolate was studied in solution and solid state. Spectral analysis of isocoumarins in concentrated solutions revealed the formation of dimers featuring pi-pi stacking supported by CHMIDLINE HORIZONTAL ELLIPSISO or CHMIDLINE HORIZONTAL ELLIPSISCl hydrogen bonds. This behaviour has been proven by DFT calculations at omega B97XD level. The center of coordination of isocoumarine to silver-containing macrocycle is the carbonyl group. Experimental data demonstrate that C--O groups interact with the silver macrocycle in the 1:1 ratio. The coordination of the carbonyl group to metallacycle observed in the solid state via cooperative COMIDLINE HORIZONTAL ELLIPSISAg3 interactions is typical for ketones. Different self-association abilities of isocoumarins lead to different coordination polymers of their complexes with the macrocycle: infinite stacks of {ABBA}infinity and {AB}infinity pattern were be obtained. The differences in supramolecular packing affect the emission properties of isocoumarins. Furthermore, the coordination of the carbonyl group to silver atoms leads to phosphorescence.

Automated summary

The complexation between 6-substituted isocoumarins and cyclic trinuclear silver pyrazolate was studied in solution and solid state. It was found that the structure and emission properties of these complexes are influenced by the self-association abilities of isocoumarins.