Since the first reports of efficient electroluminescence from an organic thin film device using the metal chelate tris(8-hydroxyquinoline)aluminum(Alq

3

) as the emissive layer materials

some efforts have been devoted not only to tailor emission wavelength by a functional group introduced onto the quinolinolato ligand

but also to synthesize the new metal chelating compound.However

there is no report on the relationship between the substituent of phenyl moiety in the 2-position of 8-quinolinol and an emission property.Therefore

a systematic study to clarify a relationship between a molecular structure and emission property is evidently necessary for developing a more useful emissive compound.Bis(2-phenyl-8-hydroxyquinolato)zinc and bis(8-hydroxyquinolato)zinc were synthesized firstly according to the relating reference.The melting point

composition and structure were also determined by a series test methods.The substituent of phenyl group dependence of luminescence band of the 8-quinolinolato anions was systematically investigated with excitation spectra and emission spectra of prepared samples.The luminescence band at 495nm for bis(8-hydroxyquinolato)zinc is presented under 225

283

348

395nm excitations

respectively.The luminescence band at 521nm for bis(2-phenyl-8-hydroxyquinolato)zinc is presented under 225

283

348

395

465nm excitation

respectively

which showed to exhibit strong photoluminescence efficiency.It is suggested that the assignment of absorption bands at 225

283

348nm of the above mentioned two samples could be ascribed to the β

ρ and α band of π

→

π

*

transition in the quinolinolato ring.The absorption bands at 395nm existing in the above mentioned two samples have been probably attributed to the charge transfer between the d orbital on zinc ion and vacant π orbital on the ligand.The new absorption band of 465nm presented in bis(2-phenyl-8-hydroxyquinolato)zinc chelate is a new energy level ascribed to the intramolecular charge transfer between the different conjugating π systems existed in the quinolinolato ring and in the substituent of phenyl moiety in the 2-position of 8-quinolinol

which also means that this new chelate exhibits photostimulated luminescence not only with ultraviolet radiation

but also visible light at room temperature.It is suggested that introducing the substituent of phenyl moiety in the 2-position of 8-quinolinol is an effective way for red shifted emission

which changes the energy level of the highest occupied molecular orbital(HOMO) through π orbital interactions.Further

insight into the detailed mechanism of photostimulated luminescence from bis(2-phenyl-8-hydroxyquinolato)zinc chelate requires additional experimental and theoretical studies.Industrially the photostimulated luminescence phenomenon of the detailed mechanism of photostimulated luminescence from bis(2-phenyl-8-hydroxyquinolato)zinc could have use as a new type fluorescent material for optical memories and organic light emission devices.