In accordance with the present invention, there is provided an organometallic luminescent material selected from {HEAD ~ the group} consisting of {TAIL ~ the compounds} of formulae to  
In accordance with the present invention , there is provided an organometallic luminescent material selected from { HEAD ~ the group } consisting of { TAIL ~ the compounds } of formulae to
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH