The formation of a hydrated homochiral helix from an achiral zwitterionic salt, spontaneous chiral symmetry breaking and redox chromism of crystals.

A unique supramolecular helix assisted by water tetramers is obtained by static evaporation of aqueous solution of a zwitterionic salt, 1,1'-bis(4-carboxylatebenzyl)-4,4'-bipyridinium; spontaneous chiral symmetry breaking occurs in crystallization; interestingly, redox chromism behavior of crystals upon exposure to alcohol atmosphere has been observed.

Tris(dibenzoyl-methanido-κO,O')[(6R,8R)-(-)-7,7-dimethyl-3-(2-pyrid-yl)-5,6,7,8-tetra-hydro-6,8-methano-isoquinoline-κN,N']terbium(III).

In the title compound, [Tb(C(15)H(11)O(2))(3)(C(17)H(18)N(2))], the 7,7-dimethyl-3-(2-pyrid-yl)-5,6,7,8-tetra-hydro-6,8-methano-iso-quin-oline (L(RR)) ligand coordinates to Tb(III) through the two N atoms of the heterocycle. The metal centre is also chelated by three deprotonated 1,3-diphenyl-propane-1,3-dione (dbm) ligands, forming enanti-omerically pure [Tb(dbm)(3)L(RR)]. The Tb(III) atom is located in a distorted square anti-prism of eight coordinating atoms (six O and two N atoms).

4-Amino-3-(4-pyrid-yl)-1,2,4-triazole-5(4H)-thione.

In the title mol-ecule, C(7)H(7)N(5)S, the pyridyl and triazole rings form a dihedral angle of 20.07 (6)°. Inter-molecular N-H⋯N hydrogen bonds link the mol-ecules into chains extended in the direction [10]. Further stability is provided by π⋯π stacking inter-actions, indicated by short distances between the centroids of triazole rings [3.480 (5) Å] and pyridyl rings [3.574 (5) Å] of neighbouring mol-ecules.