A Synergetic Mechanism of Gel-Incorporation Induced Single Crystal Dyeing

Dye doping can optimize the optical, thermal, and mechanicalpropertiesof crystal materials. It has been found that gel-incorporation intothe crystals can effectively guide the dyeing process of gel-growncrystals, where the binding interaction between gel-networks and dyemolecules plays a significant role. In this paper, Eosin B and EosinY dyes with relatively weak gel-dye interaction were takeninto consideration for the first time. Both dyes failed to stainKDP single crystals in solutions. However, with uniform gel-incorporation,KDP crystals grown from silica gels occluded the eosin dyes anisotropically.When the crystal growth slowed and the gel could not be embedded,the dyes were also unable to stain the KDP crystals. The findingsin this work reveal a synergetic mechanism in which the specific electrostaticattraction between certain KDP facets and dye anions is enhanced bygel-incorporation, since the dye desorption from KDP surfaces is restrictedby the interconnected gel-networks that physically bound on growingcrystals. Eosin B and Eosin Y dyes, which cannotstain KDP crystalsgrown in solutions, are able to anisotropically stain KDP single crystalswhen crystals are grown in silica gels, together with uniform gel-incorporationin these gel-grown crystals, revealing a synergetic mechanism wherethe specific absorption of eosin anions on cationic KDP {101} sectorsis enhanced by the gel-incorporation.