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Novel profluorescent nitroxides bearing a triazole linker between the coumarin fluorophore and an isoindoline nitroxide were prepared in good yields using the copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition reaction (CuAAC). Nitroxides containing 7-hydroxy and 7-diethylamino substitution on their coumarin rings displayed significant fluorescence suppression, and upon reaction with methyl radicals, normal fluorescence emission was returned. The fluorescence emission for the 7-hydroxycoumarin nitroxide and its diamagnetic analogue was found to be strongly influenced by pH with maximal fluorescence emission achieved in basic solution. Solvent polarity was also shown to affect fluorescence emission. The significant difference in fluorescence output between the nitroxides and their corresponding diamagnetic analogues makes these compounds ideal tools for monitoring processes involving free-radical species.

The crystal structure of the title compound, [Cu(C(26)H(22)P(2))(2)][CuCl(2)], is composed of discrete Cu(dppey)(2)](+) cations [dppey is cis-bis-(diphenyl-phosphino)ethene] and [CuCl(2)](-) anions. The tetra-hedral Cu(P-P)(2) core of the [Cu(dppey)(2)](+) cation is distorted, with Cu-P bond lengths ranging from 2.269 (1) to 2.366 (1) Å. The five-membered -Cu-P-CH=CH-P- rings adopt envelope conformations, with the Cu atom lying 0.38 and 0.65 Å out of the P-C=C-P planes. The Cu-Cl distances in the [CuCl(2)](-) anion are 2.094 (2) and 2.096 (2) Å, with a Cl-Cu-Cl angle of 176.81 (7)°.

The mol-ecules of the title compound, C(18)H(20)O(3), display an intra-molecular O-H⋯O hydrogen bond between the hydr-oxy donor and a ketal O-atom acceptor. In the crystal, inter-molecular C-H⋯π inter-actions connect adjacent mol-ecules into chains parallel to the b axis.

The mol-ecules of the title compound, C(16)H(16)O(2), display an intra-molecular O-H⋯O hydrogen bond between the hydroxyl donor and the ketone acceptor. Inter-molecular C-H⋯π inter-actions connect adjacent mol-ecules into chains that propagate parallel to the ac diagonal. The chains are arranged in sheets, and mol-ecules in adjacent sheets inter-act via inter-molecular O-H⋯O hydrogen bonds.