Substituent Effects in the Crystal Packing of Derivatives of 4′-Phenyl-2,2′:6′,2″-Terpyridine

Abstract

We report the preparation of a series of new 4′-substituted 2,2′:6′,2″-terpyridines: 4′-(3,5-dimethylphenyl)-2,2′:6′,2″-terpyridine (2), 4′-(3-fluoro-5-methylphenyl)-2,2′:6′,2″-terpyridine (3), 4′-(3,5-difluorophenyl)-2,2′:6′,2″-terpyridine (4), and 4′-(3,5- bis(trifluoromethyl)phenyl)-2,2′:6′,2″-terpyridine (5). The compounds have been characterized by mass spectrometry, solid-state IR spectroscopy and solution NMR and absorption spectroscopies. The single-crystal X-ray diffraction structures of 3, 5 and 6·EtOH (6 = 4′-(3,5-bis(tert-butyl)phenyl)-2,2′:6′,2″-terpyridine) have been elucidated. The molecular structures of the compounds are unexceptional. Since 3 and 5 crystallize without lattice solvent, we are able to understand the influence of introducing substituents in the 4′-phenyl ring and compare the packing in the structures with that of the previously reported 4′-phenyl-2,2′:6′,2″-terpyridine (1). On going from 1 to 3, face-to-face π-stacking of pairs of 3-fluoro-5-methylphenyl rings contributes to a change in packing from a herringbone assembly in 1 with no ring π-stacking to a layer-like packing. The latter arises through a combination of π-stacking of aromatic rings and N…H–C hydrogen bonding. On going from 3 to 5, N…H–C and F…H–C hydrogen-bonding is dominant, supplemented by π-stacking interactions between pairs of pyridine rings. A comparison of the packing of molecules of 6 with that in 1, 3 and 5 is difficult because of the incorporation of solvent in 6·EtOH.

Multi-faceted elastic flexibility of 1-naphthyl and 9-anthryl 2,2′:6′,2′′-terpyridine crystals

“…S14 and S15†). 9 a ,11 b Although not attempted in this study, these multi-faceted elastic crystals are likely to exhibit different luminescence properties depending on their bending direction because of their different bending mechanisms.…”

“…Terpyridine and its derivatives have been used in the production of numerous complexes using various metal ions due to their remarkable coordination capabilities, which are known to exhibit a wide variety of interesting structural, photophysical, electrochemical properties, and so on. 9,10 Since terpyridine derivatives are expected to exhibit flexibility to relieve internal stress by weak interactions such as π⋯π, N⋯H and CH⋯π, 11 namely “structural buffers”, when external stress is applied, we chose those substituted with luminescent aromatic groups to fabricate organic crystals with both flexibility and luminescence. The solid-state luminescence of terpyridine compounds introduced by naphthyl ( 1 ) and anthryl ( 2 ) moieties (Fig.…”

“…The solid-state luminescence of terpyridine compounds introduced by naphthyl ( 1 ) and anthryl ( 2 ) moieties (Fig. 1) has been characterized, 10 a ,11 b but their flexibility and other physical properties have not yet been examined, so we report their crystal structures, nanoindentations, and energy framework calculations in detail.…”

Fine-Tuning Metal and Ligand-Centered Redox Potentials of Homoleptic Bis-Terpyridine Complexes with 4′-Aryl Substituents

“…Synthetic Details. The characterization of L = 2-OMe, 60 3-OMe, 61 4-OMe, 61 3,5-OMe, 62 3,4,5-OMe, 63 2,4-OMe, 64 2,4,6-OMe, 63 3,4,5-F, 65 2-CF3, 66 3-CF3, 67 4-CF3, 68 3,5-F, 69 3,5-CF3, 69 3-Br, 70 and 3,5-Br 71 is consistent with that previously reported. To the best of our knowledge, 2,6-F and 3-CF3,4-OMe have not been reported previously.…”