Singlet oxygen production by pyrano and furano 1,4-naphthoquinones in non-aqueous medium.

The influence of ring size on the photobehaviour of condensed 1,4-naphthoquinone systems, such as pyrano- and furano-derivatives (1 and 2, respectively) has been investigated. The absorption spectra for both families of naphthoquinones reveal clear differences; in the case of 2 they extend to longer wavelengths. A solvatochromic red shift in polar solvents is consistent with the π,π* character of the S(0)→ S(1) electronic transition in all cases.

2-(4-Methyl-phen-yl)-1H-anthraceno[1,2-d]imidazole-6,11-dione: a fluorescent chemosensor.

In the title compound, C(22)H(14)N(2)O(2), the five rings of the mol-ecule are not coplanar. There is a significant twist between the four fused rings, which have a slightly arched conformation, and the pendant aromatic ring, as seen in the dihedral angle of 13.16 (8)° between the anthraquinonic ring system and the pendant aromatic ring plane.

Three N2-benzoyloxybenzamidines: sheet structures built from hard and soft hydrogen bonds and aromatic pi-pi stacking interactions.

Molecules of the title compounds N(2)-(benzoyloxy)benzamidine, C(14)H(12)N(2)O(2), (I), N(2)-(2-hydroxybenzoyloxy)benzamidine, C(14)H(12)N(2)O(3), (II), and N(2)-benzoyloxy-2-hydroxybenzamidine, C(14)H(12)N(2)O(3), (III), all have extended chain conformations, with the aryl groups remote from one another. In (I), the molecules are linked into chains by a single N-H..