Thermal and optical properties of red luminescent glass forming symmetric and non symmetric styryl-4H-pyran-4-ylidene fragment containing derivatives

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 110 °C 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 0.54, 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.

► We synthesize small organic molecules which form glass from volatile organic solvents.
► Glass transition temperature of synthesized compounds is higher than 110 °C.
► Investigated dyes in the polymer films show higher PLQY compared to similar dyes.
► Trityloxyethyl groups results in less molecule aggregation in the polymer films.