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Anthracene derivatives (1, 2) having one or two diethylamine (a), N-methyl-piperazine (b) and N,N-bis(2-dipicolyl)amine units (c) showed weak emission, suggesting that photoinduced electron transfer (PET) from the amine group to the excited anthracene occurs. The PET fluoroionophores (1, 2) were found to display unique photophysical properties in the presence of the guest metal salts. Complexation of diethylamine (1a, 2a) and N-methyl-piperazine derivatives (1b, 2b) with Ni 2+ , Cu 2+ and Zn 2+ enhanced the emission, while the emission intensities of N,N-bis(2picolyl)amine derivatives (1c, 2c) are increased in the presence of Zn 2+ and decreased in the presence of Ni 2+ and Cu 2+ . The crystal structures of 2c and its zinc chloride complex showed that the binding of Zn 2+ to the N,N-bis(2-picolyl)aminomethyl unit inhibits the photoinduced electron transfer process. Intramolecular p-p interactions between anthracene and the ZnCl 2 -complexed pyridine were observed.

New troponoid liquid crystals (1–4) with a bitropone core were prepared. The ester derivatives (1) had enantiotropic smectic A and/or C phases with higher thermal stabilities than the corresponding benzenoid derivatives (5), which had a smectic B phase. The amide derivatives (3) had an enantiotropic smectic A phase, but the ether (2) and alkylamine (4) derivatives were not mesomorphic. The crystals of 1c had a layer structure with an intermolecular π–π interaction between the bitropone cores. X-ray diffraction studies revealed that the layer spacings of the smectic A and C phases of 1i were not very much different.

Key indicatorsSingle-crystal X-ray study T = 123 K Mean (C-C) = 0.004 Å R factor = 0.117 wR factor = 0.226 Data-to-parameter ratio = 20.1 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. # 2005 International Union of Crystallography Printed in Great Britain -all rights reservedThe title compound, C 36 H 58 N 2 O 3 , also known as a liquid crystalline material, has a phase sequence of crystal-smectic C-isotropic liquid. The two benzene rings are nearly coplanar with the central NNO group, and each paraffin chain has an all-trans conformation. The molecules form a tilted layer structure via intermolecular -, C-HÁ Á ÁO and C-HÁ Á Á interactions.