Formation of Thermotropic and Lyotropic Liquid Crystals of Bis( N ‐alkylethylenediamine)silver( I ) Nitrate

We have synthesized bis( N ‐hexylethylenediamine)silver( I ) nitrate ([Ag(hex‐en) 2 ]NO 3 ), bis( N ‐octylethylenediamine)silver( I ) nitrate ([Ag(oct‐en) 2 ]NO 3 ), and bis( N ‐dodecylethylenediamine)silver( I ) nitrate ([Ag(dod‐en) 2 ]NO 3 ) and investigated the aggregation behavior of [Ag(dod‐en) 2 ]NO 3 and [Ag(oct‐en) 2 ]NO 3 in the liquid state. An X‐ray crystallographic analysis revealed that [Ag(dod‐en) 2 ]NO 3 has a dinuclear structure in the crystalline state — the molecular composition unit is [Ag 2 (dod‐en) 4 ](NO 3 ) 2 , where the two dod‐en ligands bridge two silver ions that are coordinated by four nitrogen atoms. The dinuclear complex is appreciably dissociated into a mononuclear complex in solution. It was found that [Ag(oct‐en) 2 ]NO 3 and [Ag(dod‐en) 2 ]NO 3 form thermotropic liquid crystals in the temperature ranges 48−67 °C and 59−96 °C, respectively, and a lyotropic liquid crystal was also observed for [Ag(dod‐en) 2 ]NO 3 in n ‐heptane at around room temperature in the presence of a small amount of water. The structures of the thermotropic and lyotropic liquid crystals of [Ag(dod‐en) 2 ]NO 3 were identified as a typical smectic A (S A ) type and a nematic one, respectively. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)