Compounds comprising phosphorescent metal complexes comprising cyclometallated imidazo[1,2-f]phenanthridine and diimidazo[1,2-a:1,2-c]quinazoline ligands, or isoelectronic or benzannulated analogs thereof, are described. Organic light emitting diode devices comprising these compounds are also described.

The present disclosure discloses a novel multi-stable and erasable anti-counterfeiting technology with controlled reflection color and the application thereof in optical coding. The method and use are characterized by high thermal stability and robust fatigue resistance, and the realization thereof relies on the material system composed of an intrinsic chiral diarylethene molecule based on steric hindrance ethene bridge and a liquid crystal (LC) material disclosed herein. The diarylethene based on steric hindrance ethene bridge has the following structural feature: ##STR00001## The material system composed of a diarylethene compound based on steric hindrance ethene bridge and an LC can be prepared by a simple preparation process from cheap raw materials, can achieve a wide spectral color adjustment range, and has excellent thermal stability and fatigue resistance, which is expected to be further widely used in the fields of dual erasable anti-counterfeiting and optical information encoding with high thermal stability and strong fatigue resistance.

An infrared-emitting compound has a structure represented by the following Formula (1a). In Formula (1a), Ar and ring A each independently represent an aryl ring, a heteroaryl ring or a fused ring thereof. Q-Ar represents an infrared-emitting residue. R.sub.1 represents a group in which a dihedral angle between Ar and ring A is 45 degree or more. And a thick line represents a single bond or a double bond. ##STR00001##

A fluorescence intensity enhancer containing a water-soluble compound having a melting point of 50 C. or higher, a fluorescence intensity enhancing method of a fluorescently labeled target biological substance using the fluorescence intensity enhancer, and a kit for fluorescence detection containing the fluorescence intensity enhancer.