Synthesis Of Hemicyanine Dyes And Study On Its Structure-performance-relationship

Hemicyanine dyes, usually having large conjugated system and rigid plane, possessing high molar optical absorption coefficient, wide spectral range and high fluorescence quantum yield, were widely used in various fields. However, textile-used fluorescent dye shows poor light stability, thus experimental and calculating study of two D-π-A type hemicyanine dye, namely 1,3,3-trimethyl-trans-2-[p-(N,N-Diethyl)-amino-styryl]-N-methyl indolinium chlorate (hereafter referred to as DYE-YD) and trans-4-[p-(N,N-Diethyl)-amino-styryl]-N-ethyl pyridinium bromide (hereinafter referred to as DYE-BD), and six macromolecular and small molecular dyes that are structurally similar to DYE-BD were performed. Influence on the photostability of dyes by changing electron acceptors, substituent molecular size were evaluated.Through dyeing and photofading process of acrylics and photodegradation tests of aqueous solution of two self-prepared hemicyanine dyes DYE-YD and DYE-BD, we acquired experimental data on photostability of those two dyes. It was demonstrated that with the extension of irradiation time, the chromatic aberrations of dyed acrylics increase, while K/S value and reflectance decrease. Acrylics colored with DYE-BD faded more quickly and severely than acrylics dyed with DYE-YD. Photodegradation reaction of two dyes accords with zero order kinetics decay, and DYE-BD has bigger decomposition rate constant than DYE-YD.Through Density Frontier Theory study (DFT), we obtained stable configurations of [DYE-BD]+and [DYE-YD]+. By calculating and analyzing the frontier molecular orbitals and interactions with various forms of oxygen, we found that [DYE-YD]+has higher energy gaps with oxygens and fewer reaction sites, while [DYE-BD]+shows the opposite property. So we may draw the conclusion that DYE-YD has better performance in light stability than DYE-BD and it shows good agreement in calculating and experimental results.Based on previous works, the design and synthesis of a double hydroxy styrene indole salt hemicyanine dye 1,3,3-trimethyl-trans-[4-(N,N-hydroxyl ethyl) amino styryl]-N-methyl indole chlorate (hereafter called DYE-2HYD) were completed. Properties of DYE-2HYD aqueous solution and acrylic dyeing performances were explored. DYE-2HYD possesses fairly good light stability, though slightly decrease in contrast with structurally similar DYE-YD, still, is better than that of styrene pyridinium salt. What’s more, the introduction of reactive hydroxyl group helps improve color shade and fastness, and provides possibility for the preparation of macromolecular dyes in the near future.