Fabrication and Characterization of Quinacridones Nanocrystals by High-Temperature and High-Pressure Crystallization Method

Abstract

The high-temperature and high-pressure liquid (HTPL) crystallization method was proved to be effective to fabricate nanocrystals of quinacridone and its dimethyl derivative. The quinacridone nanocrystals were spherical shape and monodispersed with the average size of around 50 nm, respectively. It was found that quinacridone nanocrystal in different crystal form could be obtained by changing experimental conditions in HTPL method.

Size-controlled production of quinacridone nanocrystals using hot compressed water recrystallization method

“…Several synthetic methods have been proposed for such materials, such as laser ablation [1], sol-gel [2], and reprecipitation [3,4]. We previously reported a hot compressed water (HCW) recrystallization method as a possible technique for preparing organic nanocrystals [5][6][7] according to which, HCW, which has a low dielectric constant (ε) of between 5 and 50, is used to form a saturated or supersaturated solution that is mixed with water at room temperature to initiate solute precipitation [8]. Many organic compounds that are sparingly soluble in room temperature water can dissolve easily in HCW [8,9].…”

“…Although studies have been made of the HCW recrystallization method [5][6][7]10], the 4 precipitation mechanism is unclear. To translate the method to an industrial scale, it would be useful to understand the relationship between particle size and the experimental factors associated with nucleation, crystal growth and solubility.…”

“…The effluent was quenched to room temperature after the mixing point with an external water jacket. 6 The temperature in the cell was maintained within ±0.1 K using a sheathed heater located along the inner wall. The saturation temperature is referred to as T and the solution temperature after mixing as T 0 .…”

Quinacridone Solubility in Hot-Compressed Water

“…Nanocrystals of quinacridone and its derivatives are attracting much attention because of promising application for electroluminescent materials and red pigments . Among several fabrication methods of these organic nanocrystals, the hot-compressed water (HCW) recrystallization method is one of the effective and environmentally friendly techniques for preparation of organic nanocrystals such as phthalocyanine, quinacridone, and fullerene C60. − In this method, HCW is used as an extraction solvent because HCW has a low dielectric constant (about 5 to 50) compared with water at room temperature (around 80) and at these conditions it behaves like a weakly polar organic solvent and also shows higher solubility to organic compounds. With this method, organic nanocrystals successfully precipitate by mixing the extracted organic aqueous solution with cooling water without any organic solvents .…”

Continuous Production of Quinacridone Nanocrystals and Control of Crystal Form by High-Temperature Water Crystallization Method

“…Recently, our group proposed a new recrystallization method using high-temperature water as the solvent and succeeded in preparing nanocrystals of some organic compounds with low-solubility phthalocyanine, quinacridone, and fullerene C 60 . [6][7][8] In this method, HTW is flowed into a static-type extraction cell (ca. 15 cm 3 ) and organic crystals are dissolved in HTW.…”