A fluorescent nanocomposite which includes a thallium doped gadolinium chalcogenide having formula Tl.sub.xGd.sub.1-xY, wherein x is 0.01 to 0.1, and Y is selected from the group consisting of S, Se, or Te, and a benzothiazolium salt bound to a surface of the thallium doped gadolinium chalcogenide. A method of detecting antimony ions in a fluid sample whereby the fluid sample is contacted with the fluorescent nanocomposite to form a mixture, and a fluorescence emission profile of the mixture is measured to determine a presence or absence of antimony ions in the fluid sample, wherein a reduction in intensity of a fluorescence emissions peak associated with the fluorescent nanocomposite indicates the presence of antimony ions in the fluid sample.

Disclosed are functionalizable ligands, nanoparticles, preferably nanocrystals, complexed with ligands and their use for bio-imaging. A nano material includes a nanoparticle and at least one copolymer ligand. A ligand which is a copolymer of general formula (I): HP[(A)x-co-(B)y]n-L-R.

A luminescent composition of matter is characterized by the formula REM.sub.2+xE.sub.y, where RE may be one or more Rare Earth elements (for example, Eu or Gd), M may be one or more elements selected from the group Al, Ga, B, In, Sc, Lu, and Y; E is one or more elements selected from the group S, Se, O, and Te; x is greater than zero; and y has the value that achieves charge balance in the formula assuming that E has a charge of 2.

Provided is an oxysulfide luminescent material. The luminescent material has a general chemical formula of Ln.sub.2xO.sub.2S:Eu.sub.x.sup.3+@M.sub.y, wherein@ is coating, Eu is doped in Ln.sub.2xO.sub.2S, Ln.sub.2xO.sub.2S:Eu.sup.x.sub.3+has a porous structure, and M is located in pores of the Ln.sub.2xO.sub.2S:Eu.sub.x.sup.3+. In the oxysulfide luminescent material, metal nano particles coating is used to form a core-shell structure, which increases luminescent efficiency of the oxysulfide luminescent material in a same excitation condition; in addition, a hollow structure is formed between a core and a shell layer of the oxysulfide luminescent material, which effectively reduces usage of rare earth elements in the shell layer and lowers cost of the luminescent material. Also provided is a preparation method for the oxysulfide luminescent material.