Glass-forming nonsymmetric DWK-dyes with 5,5,5-triphenylpentyl and piparazine moieties for light-amplification studies

Abstract

A series of 2,6-bis-styryl-4H-pyran-4-ylidene fragment containing glass-forming organic compounds with bonded amorphous phase promoting bulky triphenyl moieties through piperazine structural fragment [2-(2-(4-(bis(2-(trityloxy)ethyl)amino)styryl)-6-methyl-4H-pyran-4ylidene)malononitrile derivatives (DWK)-T dyes] in a form of (5,5,5-triphenylpentyl)piperazin-1-yl)styryl)substituent attached to the 4H-pyran-4-yliden fragment in two-position have been synthesized and investigated as the potential light-amplification medium for organic solid-state lasers. DWK-T dye physical properties also depend on the structure of the other styryl-substituent attached to the 4H-pyran-4-ylidene backbone fragment in six-position. Thermal stability of synthesized dyes is above 312°C with the glass transitions from 97°C and up to 109°C. Obtained neat pure spin-cast films based on these compounds show photoluminescence with λ max in range from 672 to 695 nm, ASE λ max from 690 to 704 nm with ASE threshold values in range from 327 to 1091 μJ∕cm 2 , which are mostly influenced by the nature of the electron transition characteristics of various four substituents in a 6-styryl-fragment. The proposed synthetic approach could be useful for obtaining chemically stable and covalently bonded bulky triphenyl group containing glassy dyes, while the synthetic design allows to acquire different nonsymmetric 2,6-bis-styryl-4H-pyran-4ylidene fragment-containing compounds for red and infrared light-emitting and light amplification applications.

HAPPY Dyes as Light Amplification Media in Thin Films

“…Surprisingly, the ASE effect was detected in MWK-2 and EWK-2 films in the infrared (IR) region. Even though PLQYs in MWK-2 and EWK-2 films were low and thresholds were relatively high, the efficiency of these materials is competitive with IR radiation amplifying compounds obtained previously. , The 10 and 20 nm red shift of EWK-2 and MWK-2 ASE peaks from their photoluminescence maximum is in accordance with the theoretical statement that the cross section of the stimulated emission should be larger to the right side of the photoluminescence maximum …”

“…To test the conversion efficiency and to tune the reaction conditions for the donor (D)–acceptor (A) group containing 4 H -pyran-4-ylidene derivative conversion into 1 H -pyridine-fragment-containing compounds, several model compounds ( 1 – 3 ) have been synthesized as described previously . Benzylamine was selected to increase the glass transition temperatures and enhance amorphous structure formation in the solid state of the desired target products.…”

“…To test the conversion efficiency and to tune the reaction conditions for the donor (D)−acceptor (A) group containing 4H-pyran-4ylidene derivative conversion into 1H-pyridine-fragment-containing compounds, several model compounds (1−3) have been synthesized as described previously. 28 Benzylamine was selected to increase the glass transition temperatures and enhance amorphous structure formation in the solid state of the desired target products. 1H-Pyridine-fragment-containing model compounds ZE-1 and JE-1 were successfully obtained (Scheme 1) by a slightly modified synthesis method reported by Kato et al 12 from 4H-pyran-4-ylidene precursors 2 and 3.…”