The effect of the nature of organic ligands and complex formation on the photoluminescent characteristics (relative quantum yield, excited state lifetime) and thermal stability of tetraden tate Schiff bases (H 2 L), derivatives of salicylaldehyde (H 2 (SAL) 1 , H 2 (SAL) 2 ), o vanillin (H 2 (MO) 1 , H 2 (MO) 2 ) with ethylenediamine and o phenylenediamine, and their zinc(II) com plexes was studied. Zinc(II) complexes were synthesized by the reaction of H 2 L with Zn(AcO) 2 •2H 2 O in MeOH at room temperature or under reflux. In the case of H 2 L = H 2 (SAL) 2 , H 2 (MO) 1 , H 2 (MO) 2 , complexes of the composition ZnL•H 2 O were isolated irrespective of the temperature. For H 2 L = H 2 (SAL) 1 , the reaction results in Zn(SAL) 1 •H 2 O at room temperature and in anhydrous dimeric complex [Zn(SAL) 1 ] 2 under reflux. Density functional calculations of H 2 L and ZnL confirmed that (1) luminescence of these compounds is due to the π-π* transition between orbitals of the organic ligand and (2) enhancement of conjugation of the chain and introduction of electron donating substituents lead to a decrease of the energy gap and, there fore, to a bathochromic shift of the emission maximum.Transition metal coordination compounds (CC) ex hibiting luminescent properties are of interest because they can be used as electroluminescent (EL) materials for or ganic light emitting diodes (OLED). 1-5 Determination of correlations between the composition, structure, and func tional properties (luminescence, thermal stability, volatil ity, conductivity, etc.) of starting CC underlies the design of new EL materials. Investigations of the effect of subs tituents in organic ligands on the photophysical proper ties of complexes have been documented. 6-8 Taking an aluminum(III) complex with 8 oxyquinoline (AlQ 3 , λ max = 525 nm) as an example, it was shown that the introduction of electron donating substituents to the ben zene fragment leads to a bathochromic shift of the emis sion maximum and to a hypsochromic shift if the substitu ent was introduced into the pyridine fragment. This effect was explained 9 by the change in the band structure. In addi tion, many researchers pay attention to the effect of intro duction of conjugated benzene rings into CC. π-π Inter action between them causes a bathochromic shift of the emission maximum 10,11 and a decrease in the quantum yield of photoluminescence, 12 as well as an increase in conductivity. 13 However, in each case the study of the effect of the nature of organic ligands on the composition and functional properties of the CC based on them is a subject of separate investigation.Among different classes of zinc(II) CC, which are of interest as the EL materials, complexes with organic ligands containing the azomethine C=N bond and a donor oxygen or nitrogen atom are of special interest because these systems exhibit intense luminescence in the blue re gion of the visible spectrum. 1,4,14-16 Interest in the search for new sources of blue luminescence is due to the fact that efficient EL material...

Nanostructures in the form of 1.2-nm-thick colloidal CdSe nanoplatelets rolled into scrolls are investigated. The morphology of these scrolls is analysed and their basic geometric parameters are determined (diameter 29 nm, longitudinal size 100 -150 nm) by TEM microscopy. Absorption and photoluminescence spectra of these objects are recorded, and the luminescence decay kinetics is studied. It is shown that the optical properties of CdSe nanoscrolls differ significantly from the properties of CdSe quantum dots and that these nanoscrolls are attractive for nanophotonic devices due to large oscillator strengths of the transition, small widths of excitonic peaks and short luminescence decay times. Nanoscrolls can be used to design hybrid organic -inorganic pure-color LEDs with a high luminescence quantum yield and low operating voltages.

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