Crystallographic and Computational Study of 4'-(Isoquinolin-5-yl)-2,2':6',2''-terpyridine and the Comparison with Its Structural Isomer 4'-(Isoquinolin-4-yl)-2,2':6',2''-terpyridine

Abstract—

The title compound consists of a 2,2':6',2"-terpyridine nucleus (tpy) completed by a pendant isoquinoline group (isq) bound at the central pyridine (py) ring. The tpy nucleus departs slightly from planarity, with py_lateral–py_central interplanar angles in the range 2.24(7)°–7.90(7)°, but the isq group is instead rotated significantly from the central pyridine ring associated to a short Htpy⋅⋅⋅Hisq contact. There are no strong noncovalent interactions in the structure, the main ones being of the π⋅⋅⋅π type giving rise to columnar arrays along [010], further linked by C–H⋅⋅⋅N and C–H⋅⋅⋅π bonds into a 3D supramolecular structure. Analogies and differences with a recently published structural isomer (4'-(isoquinolin-4-yl)-2,2':6',2''-terpyridine are discussed. As a way to highlight the nature of the crystallographic differences an analysis of the pairwise intermolecular interactions energies and Hirshfeld surfaces was carry out.