Disclosed are smectic liquid crystal compounds exhibiting ferroelectric behaviour and having the formula wherein R¹ is alkyl or alkoxyalkyl, R² and R³ are each alkylene, a is an integer of at least one, b is zero or one, R' is an optically active group containing an asymmetric center and-Z- is an organic divalent core radical having parallel or coaxially extending bonds at the terminal ends thereof, the core radical having an axial ratio of at least two and being characterized by an essentially rigid and flat molecular structure. Presence of the ether-interrupted hydrocarbon tail moiety at the terminal end of the compounds provides a lowering in observed temperatures of phase transition.

Optically active, anti head-to-head coumarin dimers represented by general formula (I) or (II): a process for their preparation, optically active polyamides represented by general formula (III) or (IV), (wherein A represents a primary or secondary amine residue, and n represents an integer of 2 or more) and a process for their preparation from (I) or (II).

The invention provides a stable solid reagent for use in a prepackaged test kit for the detection of cannabinoids comprising a diazonium salt which undergoes characteristic color change when combined with a cannabinoid under basic conditions, the salt comprising an anion capable of causing the entire salt including the diazonium cation thereof to dissolve in an organic solvent when combined therewith to form a stable liquid reagent for the detection of cannabinoids. The invention also provides a stable liquid reagent comprising the aforementioned diazonium salt and an organic solvent as well as providing prepackaged reagent test kits containing the aforementioned reagents and methods for detecting cannabinoids using the reagents of the invention.