Annual Report 2012 - Latvijas Universitātes Cietvielu fizikas institūts

THERMAL AND OPTICAL PROPERTIES OF RED LUMINESCENT GLASS
FORMING SYMMETRIC AND NON SYMMETRIC STYRYL-4H-PYRAN-4-
YLIDENE FRAGMENT CONTAINING DERIVATIVES
Aivars Vembris a , Elmars Zarins b , Janis Jubels b , Valdis Kokars b , Inta Muzikante a ,
Arunas Miasojedovas c , Saulius Jursenas c
Dyes with amorphous structure deposited from organic solvents and having good fluorescence
properties show potential for photonic device applications. Organic glass-forming symmetric
and non symmetric styryl- derivatives of 2(2,6-substituted-4H-pyran-4-ylidene)-malononitrile (it
has backbone of known laser dye 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)styryl]-
4H-pyran), 2(2,6-substituted-4H-pyran-4-ylidene)-1H-indene-1,3(2H)-dione and 2(2,6-
substituted-4H-pyran-4-ylidene)-pyrimidine-2,4,6(1H,3H,5H)-trione were synthesized and
investigated. Glass transition temperatures higher than 110ºC were achieved. The absorption
bands in dichloromethane solution cover the spectral region from 450 nm to 600 nm with
fluorescence maxima between 580 nm and 690 nm. Photoluminescence quantum yields of the
compounds in solution are between 0.3 and 0.55, which is reduced by one order in thin
amorphous film prepared from volatile organic solvents. Incorporation of bulky trityloxyethyl
groups in the derivatives results in significant reduction of aggregate formation. Thus
fluorescence concentration quenching is reduced, enabling higher doping levels as compared to
the unsubstituted 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino)styryl]-4H-pyran dye.
Figure 1. Synthesis of glass forming styryl-
4H-pyran-4-ylidene fragment containing
derivatives
Table 1. Thermal properties of
synthesized compounds. T g – glass
transition temperature, T m – melting
temperature, T d – decomposition
temperature
DWK JWK ZWK
1 2 1 2 1 2
T g , - 112 120 127 110 118
T m , 250 148 146 144 212 144
T d , 267 296 266 283 274 284
Figure 2. Absorption (dashed lines) and
fluorescence (solid lines) spectra of
compounds DWK, JWK and ZWK in dilute
solutions and neat films.
Figure 3. The dependence of
photoluminescence PLQY on concentration
of DWK-1 and DWK-2 and DCM dyes in
PMMA matrix.
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